JP7204404B2 - motor driver device - Google Patents

Description

The present invention relates to a motor driver device.

A brushed DC motor includes a commutator, brushes, a rotor, and a stator, and generates torque by passing current through the coils of the rotor via the commutator and brushes. At this time, in the DC motor with brushes, the brushes wear out because the commutator and the brushes are in contact with each other (the rotor rotates).

If the degree of abrasion of the brush becomes large, it becomes impossible to perform the desired rotation, so it is necessary to take measures such as replacing the motor.

JP-A-2000-116093

However, conventional devices for driving DC motors with brushes basically have no way of knowing the state of wear of the brushes, so that the administrator or the like of the device has had to frequently check the state of wear of the brushes. There is a strong demand for the development of technology that can determine the state of wear of the brush on the device side.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a motor driver device that can satisfactorily determine the state of wear of the brushes of a DC motor with brushes.

A motor driver device according to the present invention is a motor driver device for driving a DC motor with brushes, wherein the motor current is supplied to the DC motor through an output transistor. and an abrasion determination unit that determines the abrasion state of the brush of the DC motor based on the evaluation signal (first configuration).

Specifically, for example, in the motor driver device according to the first configuration, the motor current flows between the first electrode and the second electrode of the output transistor, and the evaluation signal acquisition section obtains the A signal indicating an evaluation voltage, which is the voltage between the first electrode and the second electrode of the output transistor, may be acquired as the evaluation signal (second configuration).

At this time, for example, in the motor driver device according to the second configuration, the state of wear of the brush is divided into a first state in which the wear of the brush is relatively small and a second state in which the wear of the brush is relatively large. wherein the wear determination unit determines that the wear state of the brush belongs to the second state when the magnitude of the evaluation voltage is smaller than a predetermined determination voltage value (third configuration), good.

Further, for example, in the motor driver device according to the second configuration, the wear state of the brush is classified into a first state in which the wear of the brush is relatively small and a second state in which the wear of the brush is relatively large. The wear determination unit has a holding unit that holds a reference value based on the magnitude of the evaluation voltage at a first timing, and after a second timing after the first timing, at the second timing It may be determined whether or not the state of wear of the brush belongs to the second state (fourth configuration) by comparing the magnitude of the evaluation voltage of with the reference value.

Alternatively, for example, in the motor driver device according to the first configuration, the evaluation signal acquisition unit uses a current sensor that measures the motor current to obtain a signal indicating the magnitude of the motor current measured under the energized condition. , may be obtained as the evaluation signal (fifth configuration).

At this time, for example, in the motor driver device according to the fifth configuration, the state of wear of the brush is divided into a first state in which the wear of the brush is relatively small and a second state in which the wear of the brush is relatively large. The wear determination unit determines that the brush wear state belongs to the second state when the magnitude of the motor current indicated by the evaluation signal is smaller than a predetermined determination current value. configuration).

Further, for example, in the motor driver device according to the fifth configuration, the state of wear of the brush is classified into a first state in which the wear of the brush is relatively small and a second state in which the wear of the brush is relatively large. The wear determination unit has a holding unit that holds a reference value based on the magnitude of the motor current at a first timing, and after a second timing after the first timing, at the second timing It may be determined whether or not the state of wear of the brush belongs to the second state (seventh configuration) by comparing the magnitude of the motor current with the reference value.

Further alternatively, for example, in the motor driver device according to the first configuration, the evaluation signal acquisition unit receives, as the evaluation signal, a signal indicating an evaluation voltage, which is the voltage between both terminals of the DC motor under the energized condition. A configuration (eighth configuration) for obtaining the information may be used.

At this time, for example, in the motor driver device according to the eighth configuration, the state of wear of the brush is divided into a first state in which the wear of the brush is relatively small and a second state in which the wear of the brush is relatively large. wherein the wear determination unit determines that the wear state of the brush belongs to the second state when the magnitude of the evaluation voltage is greater than a predetermined determination voltage value (ninth configuration), good.

Further, for example, in the motor driver device according to the eighth configuration, the wear state of the brush is classified into a first state in which the wear of the brush is relatively small and a second state in which the wear of the brush is relatively large. The wear determination unit has a holding unit that holds a reference value based on the magnitude of the evaluation voltage at a first timing, and after a second timing after the first timing, at the second timing may be determined whether or not the state of wear of the brush belongs to the second state (a tenth configuration) by comparing the magnitude of the evaluation voltage of with the reference value.

Further, for example, in the motor driver device according to the third, fourth, sixth, seventh, ninth, or tenth configuration, the wear determination unit determines that the wear state of the brush belongs to the second state. A configuration (eleventh configuration) may be employed in which a notification unit is caused to make a predetermined notification when the time is reached.

According to the present invention, it is possible to provide a motor driver device that can satisfactorily determine the state of wear of the brushes of a DC motor with brushes.

1 is a configuration diagram of a motor drive system according to a basic embodiment of the present invention; FIG. 1 is a schematic external view of a driver IC according to a basic embodiment of the invention; FIG. FIG. 3 is a block diagram of a portion for evaluating and determining the state of wear of the brush of the motor according to the basic embodiment of the present invention; FIG. 10 is a configuration diagram of a portion related to brush wear determination, according to example EX1_1 belonging to the first embodiment of the present invention. FIG. 10 is a configuration diagram of a portion related to brush wear determination, according to example EX1_2 belonging to the first embodiment of the present invention. FIG. 10 is a configuration diagram of a portion related to brush wear determination, according to example EX1_3 belonging to the first embodiment of the present invention. FIG. 10 is a configuration diagram of a portion related to brush wear determination, according to example EX1_4 belonging to the first embodiment of the present invention. FIG. 10 is an explanatory diagram of brush wear determination according to Example EX1_5 belonging to the first embodiment of the present invention. FIG. 10 is a configuration diagram of a portion related to brush wear determination, according to example EX2_1 belonging to the second embodiment of the present invention. FIG. 10 is a configuration diagram of a portion related to brush wear determination, according to example EX2_2 belonging to the second embodiment of the present invention. FIG. 10 is an explanatory diagram of brush wear determination according to example EX2_3 belonging to the second embodiment of the present invention. FIG. 20 is a configuration diagram of a portion related to brush wear determination, according to example EX3_1 belonging to the third embodiment of the present invention. FIG. 20 is a configuration diagram of a portion related to brush wear determination, according to example EX3_2 belonging to the third embodiment of the present invention. FIG. 20 is an explanatory diagram of brush wear determination according to example EX3_3 belonging to the third embodiment of the present invention. FIG. 11 is a diagram showing connection relationships between a plurality of output transistors and a plurality of motors according to a fifth embodiment of the present invention; It is a figure which shows a mode that a motor drive system is mounted in a vehicle concerning 6th Embodiment of this invention.

Hereinafter, examples of embodiments of the present invention will be specifically described with reference to the drawings. In each figure referred to, the same parts are denoted by the same reference numerals, and redundant descriptions of the same parts are omitted in principle. In this specification, for simplification of description, by describing symbols or codes that refer to information, signals, physical quantities, or members, etc., the names of information, signals, physical quantities, or members, etc. corresponding to the symbols or codes are It may be omitted or abbreviated. For example, a source connection terminal referred to by "S[1]" (see FIG. 1), which will be described later, may be written as source connection terminal S[1] or abbreviated as terminal S[1]. are possible, but they all refer to the same thing.

First, some terms used in the description of this embodiment will be explained. Ground refers to a conductive part having a reference potential of 0 V (zero volts) or refers to the reference potential itself. In each embodiment, voltages shown without specific references represent potentials with respect to ground. A line is synonymous with wiring. A level refers to a level of potential, and for any signal or voltage a high level has a higher potential than a low level. For any signal or voltage whose level periodically switches between low level and high level, the length of the section where the level of the signal or voltage is high with respect to the length of the section of one cycle of the signal or voltage The length ratio is called duty. For any transistor configured as a FET (Field Effect Transistor), the ON state refers to the state of conduction between the drain and the source of the transistor, and the OFF state refers to the state of conduction between the drain and the source of the transistor. is in a non-conducting state (cutoff state). Hereinafter, the ON state and OFF state may be simply expressed as ON and OFF.

<<Basic embodiment>>
A basic embodiment of the present invention will be described. FIG. 1 is a configuration diagram of a motor drive system 1 according to a basic embodiment of the invention. The motor drive system 1 includes a driver IC 10, an MPU (micro-processing unit) 20, an external connection device 30, a motor 40, and output transistors M[1] to M[4]. The MPU 20, the external connection device 30, the motor 40, and the output transistors M[1] to M[4] are provided outside the driver IC10. Among them, the MPU 20 and the output transistors M[1] to M[4] are externally connected to the driver IC 10 . The external connection device 30 is connected to the MPU 20 . Motor 40 is a DC motor with brushes as a load of driver IC 10 .

The driver IC 10 includes a control logic 11 and a gate drive circuit 12, and also includes a circuit used to detect and determine the state of wear of the brushes of the motor 40, but this circuit is not shown in FIG. do). In addition to these, the driver IC 10 is provided with a charge pump circuit for generating necessary voltages and a circuit for detecting whether or not an overcurrent occurs in each output transistor. omitted.

FIG. 2 is a schematic external view of the driver IC 10. As shown in FIG. The driver IC 10 is an electronic component formed by enclosing a semiconductor integrated circuit in a housing (package) made of resin. Each circuit and each element provided in the driver IC 10 is integrated with a semiconductor. and form a semiconductor integrated circuit. A housing of the driver IC 10 is provided with a plurality of external terminals exposed to the outside of the driver IC 10 . It should be noted that the number of external terminals of the driver IC 10 shown in FIG. 2 is merely an example.

The plurality of external terminals provided in the driver IC 10 include gate connection terminals G[1] to G[4], source connection terminals S[1] to S[2] and _SCOM , and a ground terminal connected to the ground. GND, a power supply input terminal VIN for receiving a predetermined DC power supply voltage VCC (eg, 5V), and a communication/control terminal group TMG. Terminal group TMG consists of a plurality of external terminals. Any circuitry within driver IC 10, including control logic 11, is driven by power supply voltage VCC. However, some circuits in the driver IC 10 can be driven by other DC voltages different from the power supply voltage VCC as drive voltages.

Each of the output transistors M[1] to M[4] is configured as an N-channel MOSFET (metal-oxide-semiconductor field-effect transistor). Although not shown, in the MOSFETs forming each output transistor, a parasitic diode whose forward direction is the direction from the source to the drain of the MOSFET is formed and connected in parallel to the MOSFET. A modification in which the output transistors M[1] and M[2] are composed of P-channel MOSFETs is also possible.

In the configuration of FIG. 1, the output transistors M[1] to M[4] form a full bridge circuit (H bridge circuit) for the motor 40. At this time, the output transistors M[1] and M[2] function as high-side transistors, and output transistors M[3] and M[4] function as low-side transistors.

Specifically, the drains of the output transistors M[1] and M[2] are connected to a power supply line to which a predetermined positive power supply voltage VPWR (for example, 12 V) is applied, and the drains of the output transistors M[3] and M[4] are connected. Each source is connected to ground. The source of the output transistor M[1] and the drain of the output transistor M[3] are commonly connected at a node NDa, and the source of the output transistor M[2] and the drain of the output transistor M[4] are commonly connected at a node NDb. be done. A motor 40 is connected between nodes NDa and NDb.

When the current flows from the node NDa through the motor 40 toward the node NDb, the motor 40 rotates in the first rotation direction (this rotation is referred to as forward rotation), and the current flows from the node NDb through the motor 40 toward the node NDa. When the motor 40 rotates in a second direction of rotation opposite to the first direction of rotation (this rotation is referred to as reverse rotation). The current flowing through the motor 40 is called motor current. Regarding the motor current, the polarity of the current flowing from the node NDa to the node NDb is assumed to be positive, and the opposite is assumed to be negative. Also, the voltage between both terminals of the motor 40 is referred to as motor voltage. The motor voltage is equal to the voltage across nodes NDa and NDb.

Gates of the output transistors M[1] to M[4] are connected to gate connection terminals G[1] to G[4] of the driver IC 10, respectively. The sources of the output transistors M[1] and M[2] are connected to the source connection terminals S[1] and S[2] of the driver IC 10, respectively. The sources of the output transistors M[3] and M[4] are commonly connected to the source connection terminal _SCOM .

The gate drive circuit 12 is a circuit that drives the gates of the output transistors M[1] to M[4], and includes gate connection terminals G[1] to G[4] and source connection terminals S[1] to S [2] and _SCOM , and the ground terminal GND. The gate drive circuit 12, under the control of the control logic 11, individually controls the gate voltages of the output transistors M[1] to M[4] through respective terminals connected thereto, thereby controlling the output transistor M[1 ] to M[4] individually. The states of the output transistors M[1] to M[4] are controlled by turning on the output transistors M[1] to M[4] and turning off the output transistors M[1] to M[4]. Includes control to make Gate voltages of the output transistors M[1] to M[4] are represented by VG[1] to VG[4], respectively. In the driver IC 10, a charge pump circuit (not shown) or the like is used to generate an internal power supply voltage having a potential higher than the power supply voltage VPWR. and M[2] can be turned on.

The control logic 11 is capable of two-way communication with the MPU 20 via the communication/control terminal group TMG. Bidirectional communication between the control logic 11 and the MPU 20 is realized by, for example, SPI (Serial Peripheral Interface). Bidirectional communication by SPI is called SPI communication. The MPU 20 can supply a PWM signal (pulse width modulation signal) to the driver IC 10 in addition to the signal for SPI communication. When the PWM signal is supplied, the control logic 11 controls each output transistor M The gate drive circuit 12 can be controlled such that [1] to M[4] are switched.

In accordance with instructions from the MPU 20, the driver IC 10 drives the output transistors M[1] to M[4] and the motor 40 in a plurality of ways including a forward continuous drive system, a reverse continuous drive system, a forward PWM drive system, and a reverse PWM drive system. can be driven by any one of the driving methods.

In the forward continuous driving method, the output transistors M[1] to M[4] are continuously maintained on, off, off, and on, respectively (that is, the output transistors M[1] and M[4] are always on). and output transistors M[2] and M[3] are always off), positive motor current to rotate motor 40 forward continues through transistors M[1] and M[4]. 40.

In the continuous reverse drive method, the output transistors M[1] to M[4] are continuously kept off, on, on, off, respectively (ie, the output transistors M[2] and M[3] are always on). and output transistors M[1] and M[4] are always off), and negative motor current to reverse motor 40 is continuously applied to motor 40 through transistors M[2] and M[3]. supplied.

In the forward PWM driving method, the output transistors M[1] and M[4] are driven based on the first PWM signal supplied from the MPU 20 while the output transistors M[2] and M[4] are kept off and on, respectively. 3] are switching driven. The first PWM signal is a binary signal that takes a high level or a low level. When the first PWM signal is at a high level, the output transistors M[1] and M[3] are turned on and off, respectively. When the signal is at the low level, the output transistors M[1] and M[3] are turned off and on, respectively. Therefore, in the forward PWM driving method, a positive motor current corresponding to the duty of the first PWM signal flows through the output transistors M[1], M[3], and M[4] to the motor 40, and the motor 40 rotates forward. It will be.

In the reverse PWM driving method, the output transistors M[2] and M[4] are turned on based on the second PWM signal supplied from the MPU 20 while the output transistors M[1] and M[3] are kept off and on, respectively. ] are switching driven. The second PWM signal is a binary signal that takes a high level or a low level. When the second PWM signal is at a high level, the output transistors M[2] and M[4] are turned on and off, respectively. When the signal is at a low level, output transistors M[2] and M[4] are turned off and on, respectively. Therefore, in the reverse PWM driving method, a negative motor current corresponding to the duty of the second PWM signal flows to the motor 40 through the output transistors M[2], M[3] and M[4], causing the motor 40 to rotate in reverse. Become.

The external connection device 30 includes a light emitting element, a display device, and the like connected to the MPU 20. How to use the external connection device 30 will be described later.

As is well known, a brushed DC motor is configured with a commutator, brushes, a rotor, and a stator, and generates torque by applying current (motor current) to coils of the rotor via the commutator and brushes. At this time, in the DC motor with brushes, the brushes wear out because the commutator and the brushes are in contact with each other (the rotor rotates). The brushes described below refer to brushes provided in the motor 40, which is a DC motor with brushes, unless otherwise specified.

Referring to FIG. 3A, the motor drive system 1 is provided with an evaluation signal acquisition section 60 and an abrasion determination section 70, which can be used to evaluate and determine the abrasion state of the brush. Although the detailed configuration will be described later, both the evaluation signal acquisition unit 60 and the wear determination unit 70 may be provided in the driver IC 10 as shown in FIG. 3B, or as shown in FIG. Alternatively, the evaluation signal acquisition section 60 may be provided in the driver IC 10 and the wear determination section 70 may be implemented in the microcomputer 20 .

Under predetermined energization conditions in which the motor current is supplied to the motor 40 through any of the output transistors M[1] to M[4], a relatively large motor current is generated when the degree of brush wear is relatively small. When the degree of brush wear is relatively high, the motor current is expected to be relatively low due to the increased contact resistance between the brushes and the commutator. Using this characteristic, the evaluation signal acquisition unit 60 determines the magnitude of the motor current under a predetermined energization condition in which the motor current is supplied to the motor 40 through any of the output transistors M[1] to M[4]. A dependent evaluation signal is acquired, and the wear determination unit 70 determines the wear state of the brushes of the motor 40 based on the evaluation signal.

The predetermined energization condition is a forward rotation continuous energization condition in which the motor current is supplied to the motor 40 by the forward rotation continuous drive method, or a reverse rotation continuous energization condition in which the motor current is supplied to the motor 40 by the reverse rotation continuous drive method. and good. However, the predetermined energization condition is a forward rotation PWM energization condition in which the motor current is supplied to the motor 40 by the forward rotation PWM drive method, or a reverse rotation PWM energization condition in which the motor current is supplied to the motor 40 by the reverse rotation PWM drive method. can be Several types of evaluation signals will be mentioned below as evaluation signals, but any evaluation signal is a signal obtained under predetermined energization conditions. That is, for example, the signal obtained by the evaluation signal obtaining section 60 under the condition that all of the output transistors M[1] to M[4] are turned off is not the evaluation signal.

The state of brush wear includes a first state in which the wear of the brush is relatively small (hereinafter referred to as a good brush state), a second state in which the wear of the brush is relatively large (hereinafter referred to as a bad brush state), It is divided into When comparing the good brush state and the bad brush state, the degree of wear of the brush is greater in the bad brush state than in the good brush state, and the contact resistance between the brush and the commutator is greater. The wear determination unit 70 can determine whether the wear state of the brush belongs to the bad brush state (in other words, whether it belongs to the good brush state or the bad brush state) based on the evaluation signal.

Hereinafter, a plurality of embodiments will be described as embodiments for describing specific examples of configurations and operation examples related to brush wear, modification techniques of the driver IC 10, and the like. The matters described in the basic embodiment described above are applied to each of the following embodiments unless otherwise stated and there is no contradiction. The description in each embodiment may be given priority. In addition, as long as there is no contradiction, the matter described in any of the multiple embodiments shown below can also be applied to any other embodiment (that is, any two or more of the multiple embodiments). It is also possible to combine the embodiments of

In the following description, an arbitrary integer i from 1 to 4 may be used to refer to an arbitrary output transistor among the output transistors M[1] to M[4] by the symbol “M[i]”. be. Components other than the output transistor may be the same.

<<First Embodiment>>
A first embodiment according to the present invention will be described. In the first embodiment, the voltage between the drain and the source of the output transistor M[i] through which the motor current flows under predetermined energization conditions is treated as the evaluation voltage, and the signal indicating the evaluation voltage is used as the evaluation signal. The drain-source voltage of the output transistor M[i] refers to the potential of the drain seen from the potential of the source of the output transistor M[i]. When the motor current flows through the output transistor M[i], the motor current flows between the first electrode and the second electrode of the output transistor M[i]. Here, one of the first electrode and the second electrode is the drain and the other is the source. Hereinafter, the voltage between the drain and the source is sometimes referred to as voltage _VDS .

Since the voltage V _DS of the output transistor M[i] is expressed by the product of the on-resistance (that is, the resistance between the drain and the source) of the output transistor M[i] and the drain current of the output transistor M[i], the motor current flows as the drain current of the output transistor M[i], the voltage _VDS of the output transistor M[i] also decreases when the motor current decreases due to the large degree of brush wear. In the first embodiment, attention is paid to this characteristic, and wear determination is performed using the voltage _VDS .

It is assumed that when the output transistor M[i] is turned on, the gate voltage of the output transistor M[i] is sufficiently high and the ON resistance of the output transistor M[i] is constant.

The first embodiment includes the following examples EX1_1 to EX1_5. In Examples EX1_1 to _{EX1_5} , specific examples of performing wear determination based on the voltage VDS will be described.

[Example EX1_1]
Example EX1_1 will be described. FIG. 4 is a diagram showing a partial configuration of the driver IC 10 that contributes to the realization of operations related to the embodiment EX1_1, together with the output transistors M[1] to M[4] and the motor 40. As shown in FIG. In the embodiment EX1_1, the driver IC 10 is provided with a voltage source 111 for generating a predetermined judgment voltage V _REF1 and a comparator 112 . The judgment voltage _VREF1 has a predetermined positive DC voltage value.

In the embodiment EX1_1, it is assumed that the motor 40 is driven under the reverse continuous energization condition. At this time, the output transistors M[1] to M[4] are turned off, on, on, off is.

In the configuration of FIG. 4, the source connection terminal S[1] to which the drain voltage of the output transistor M[3] is applied is connected to the inverting input terminal of the comparator 112, and the source connection terminal S[1] to which the source voltage of the output transistor M[3] is applied. _SCOM is connected to the negative terminal of voltage source 111 and the positive terminal of voltage source 111 is connected to the non-inverting input terminal of comparator 112 . A source-drain voltage _VDS of output transistor M[3] is applied across terminals S[1] and _SCOM . Under the reverse continuous energization condition, the voltage _VDS of the output transistor M[3] functions as the evaluation voltage, and the signal indicating the voltage _VDS of the output transistor M[3] functions as the evaluation signal Sa1. In the configuration of FIG. 4, it can be considered that the wiring and terminals for propagating the evaluation signal Sa1 constitute the evaluation signal acquisition section 60. FIG.

Since the determination voltage V _REF1 is applied to the non-inverting input terminal of the comparator 112 by inserting the voltage source 111, in the comparator 112, the voltage V _DS (that is, the evaluation voltage) of the output transistor M[3] becomes the determination voltage V _REF1 . The comparison is made, and the comparator 112 outputs a decision signal Sa2 indicating the result of the comparison. That is, the comparator 112 is at a low level when the voltage _{VDS of the output transistor M[3] is higher than the determination voltage VREF1 (} in other words, when the magnitude of the evaluation voltage is greater than the value of the determination voltage _VREF1 ). and is high when the voltage _{VDS of the output transistor M[3] is lower than the reference voltage VREF1 (} in other words, when the magnitude of the evaluation voltage is smaller than the value of the reference voltage _VREF1 ). A level determination signal Sa2 is output. When the voltage _VDS of the output transistor M[3] exactly matches the determination voltage _VREF1 , the level of the determination signal Sa2 becomes low level or high level.

In the configuration of FIG. 4 , the control logic 11 has the function of the wear determining section 70 . That is, the control logic 11 determines that the brush wear condition belongs to the good condition of the brush when the level of the determination signal Sa2 is low under the condition that the motor 40 is driven under the continuous reverse energization condition. When the level of Sa2 is at a high level, it is determined that the worn state of the brush belongs to the defective brush state.

The voltage source 111 may be formed so that the value of the determination voltage V _REF1 is variable. In this case, the value of the determination voltage V _REF1 in the voltage source 111 is set based on an instruction from the MPU 20 via SPI communication. May be. By adjusting the determination voltage _VREF1 , the threshold for determining brush wear can be adjusted, making it possible to adapt to various types of motors.

Further, in order to suppress erroneous determination due to noise, a low-pass filter is provided between the comparator 112 and the control logic 11 to reduce the high frequency components of the determination signal Sa2, and the reduced determination signal Sa2 is used to The wear state of the brush may be determined. Alternatively, the control logic 11 may have the function of the low-pass filter.

In the configuration of FIG. 4, the voltage _VDS of the output transistor M[3] is used as the evaluation voltage, but the voltage _VDS of the output transistor M[2] is used instead of the voltage _VDS of the output transistor M[3]. It may be used as an evaluation voltage.

Moreover, even when the motor 40 is driven under the reverse PWM energization condition, the method of the embodiment EX1_1 can be applied. However, in this case, an averaging circuit (not shown) for generating a temporal average voltage of the voltage V _DS of the output transistor M[2] or M[3] is added to the driver IC 10, and the obtained average voltage is compared with the determination voltage _VREF1 to generate the determination signal Sa2. Also, the duty of the PWM signal at this time is set to a certain duty (because the average voltage to be compared with the determination voltage _VREF1 depends on the duty).

[Example EX1_2]
Example EX1_2 will be described. In the embodiment EX1_1, the configuration adapted only for the reverse rotation of the motor 40 is shown, but of course, the driver IC 10 can also be provided with a configuration adapted for the forward rotation of the motor 40. FIG. That is, the configuration shown in FIG. 5 can be adopted. FIG. 5 is a diagram showing a partial configuration of the driver IC 10 that contributes to the realization of operations related to the embodiment EX1_2, together with the output transistors M[1] to M[4] and the motor 40. As shown in FIG.

In the embodiment EX1_2, the driver IC 10 is provided with a voltage source 111 and a comparator 112 used when the motor 40 rotates in reverse, and a voltage source 113 and a comparator 114 used when the motor 40 rotates forward. The voltage source 111 and the comparator 112 are the same as those shown in FIG. 4, and the connection relationship between the voltage source 111 and the comparator 112, each terminal and the output transistor, and the operation of the voltage source 111 and the comparator 112 are those of the embodiment EX1_1. is as shown in

A voltage source 113 generates a predetermined judgment voltage _VREF2 . The judgment voltage V _REF2 has a predetermined positive DC voltage value.

In the configuration of FIG. 5, the source connection terminal S[2] to which the drain voltage of the output transistor M[4] is applied is connected to the inverting input terminal of the comparator 114, and the source connection terminal S[2] to which the source voltage of the output transistor M[4] is applied. _SCOM is connected to the negative terminal of voltage source 113 and the positive terminal of voltage source 113 is connected to the non-inverting input terminal of comparator 114 . The source-drain voltage _VDS of output transistor M[4] is applied across terminals S[2] and _SCOM .

As described above in the embodiment _{EX1_1} , under the reverse continuous energization condition, the voltage VDS of the output transistor M[3] functions as the evaluation voltage, and the signal indicating the voltage _VDS of the output transistor M[3] is the evaluation signal. Functions as Sa1. On the other hand, under the forward continuous energization condition, the voltage _VDS of the output transistor M[4] functions as the evaluation voltage, and the signal indicating the voltage _VDS of the output transistor M[4] functions as the evaluation signal Sa3. In the configuration of FIG. 5, it can be considered that the wirings and terminals for propagating the evaluation signals Sa1 and Sa3 constitute the evaluation signal acquisition section 60. FIG.

Since the operations of the voltage source 111 and the comparator 112 involved in the reverse rotation are as shown in the embodiment EX1_1, the operations of the voltage source 113 and the comparator 114 involved in the forward rotation will be described. By inserting the voltage source 113, the non-inverting input terminal of the comparator 114 is applied with the determination voltage _VREF2 . Therefore, the comparator 114 compares the voltage V _DS (that is, the evaluation voltage) of the output transistor M[4] with the determination voltage V _REF2 , and the comparator 114 outputs a determination signal Sa4 indicating the comparison result. be done. That is, the comparator 114 is at a low level when the voltage _{VDS of the output transistor M[4] is higher than the determination voltage VREF2 (} in other words, when the magnitude of the evaluation voltage is greater than the value of the determination voltage _VREF2 ). and is high when the voltage _{VDS of the output transistor M[4] is lower than the reference voltage VREF2 (} in other words, when the magnitude of the evaluation voltage is smaller than the value of the reference voltage _VREF2 ). A level determination signal Sa4 is output. When the voltage _VDS of the output transistor M[4] exactly matches the determination voltage _VREF2 , the level of the determination signal Sa4 becomes low level or high level.

In the configuration of FIG. 5 , the control logic 11 has the function of the wear determining section 70 . That is, in a situation in which the motor 40 is driven under the continuous reverse energization condition, the control logic 11 pays attention to the determination signal Sa2. , and when the level of the determination signal Sa2 is at a high level, it is determined that the worn state of the brush belongs to the defective brush state. Similarly, in a situation in which the motor 40 is driven under the forward rotation continuous energization condition, the control logic 11 pays attention to the determination signal Sa4, and when the level of the determination signal Sa4 is at the low level, the wear state of the brush is When the judgment signal Sa4 is at a high level, the worn state of the brush is judged to belong to the defective brush state.

Similar to the voltage source 111 (see embodiment EX1_1), the voltage source 113 may be formed so that the value of the determination voltage V _REF2 is variable. A value of the determination voltage _VREF2 in the voltage source 113 may be set. By adjusting the judgment voltage V _REF2 , the judgment threshold for brush wear can be adjusted, making it possible to adapt to various types of motors.

Further, in order to suppress erroneous determination due to noise, a low-pass filter is provided between the comparator 114 and the control logic 11 to reduce the high-frequency components of the determination signal Sa4, and the reduced determination signal Sa4 is used to The wear state of the brush may be determined. Alternatively, the control logic 11 may have the function of the low-pass filter.

The value of the determination voltage V _REF2 may or may not match the determination voltage V _REF1 generated by the voltage source 111 . A single voltage source may be used as both the voltage sources 111 and 113 when the two match. Alternatively, a single comparator may also be used as the comparators 112 and 114 by using a single comparator in a time-sharing manner. In this case, when the motor 40 is reversed, the single comparator compares the voltage _{VDS of the output transistor M[3] with the determination voltage VREF1 ,} and the single comparator outputs the determination signal Sa2. output, and during forward rotation of the motor 40, the single comparator compares the voltage V _DS of the output transistor M[4] with the determination voltage V _REF2 to perform the single comparison. The input to the single comparator may be switched so that the decision signal Sa4 is output from the comparator.

In the configuration of FIG. 5, the voltage V _DS of the output transistor M[4] is used as the evaluation voltage during _forward rotation. may be used as the _evaluation voltage. A similar modification at the time of reverse rotation is as described in Example EX1_1.

Further, even when the motor 40 is driven under the forward rotation PWM energization condition, the method of Example EX1_2 can be applied. However, in this case, an averaging circuit (not shown) for generating a temporal average voltage of the voltage _VDS of the output transistor M[1] or M[4] is added to the driver IC 10, and the obtained average voltage is compared with the determination voltage _VREF2 to generate the determination signal Sa4. Also, the duty of the PWM signal at this time is set to a certain duty (because the average voltage to be compared with the determination voltage _VREF2 depends on the duty). A similar modification at the time of reverse rotation is as described in Example EX1_1.

[Example EX1_3]
Example EX1_3 will be described. FIG. 6 is a diagram showing a partial configuration of the driver IC 10 that contributes to the realization of operations related to the embodiment EX1_3, together with the output transistors M[1] to M[4] and the motor 40. As shown in FIG. In the embodiment EX1_3, an operational amplifier 121 and an A/D converter 122 are provided in the driver IC10, and resistors 123 and 124 are externally connected to the driver IC10.

In the embodiment EX1_3, it is assumed that the motor 40 is driven under the reverse continuous energization condition. is.

6, the source connection terminal S[1] to which the drain voltage of the output transistor M[3] is applied is connected to the non-inverting input terminal of the operational amplifier 121, and the inverting input terminal of the operational amplifier 121 is connected via the resistor 123. It is grounded and connected to its own output terminal via a resistor 124 . Since the resistors 123 and 124 are provided outside the driver IC 10, one external terminal (for example, the terminal _SCOM ) of the driver IC 10 is interposed between the inverting input terminal of the operational amplifier 121 and the resistor 123. , another external terminal of the driver IC 10 is interposed between the output terminal of the operational amplifier 121 and the resistor 124 .

An amplifier circuit is formed by operational amplifier 121 and resistors 123 and 124 . The voltage V _DS of the output transistor M[ 3 ] is amplified by the amplifier circuit, and the amplified voltage V _DS of the output transistor M[ 3 ] appears at the output terminal of the operational amplifier 121 . Under the reverse continuous energization condition, the amplified voltage VDS of the output transistor M[3] appearing at the output terminal of the operational amplifier 121 functions as the evaluation voltage, and the signal indicating the evaluation voltage functions as the evaluation signal _Sa5 . In the configuration of FIG. 6, it can be considered that a circuit for generating and propagating the evaluation signal Sa5 including the operational amplifier 121 and the resistors 123 and 124 constitutes the evaluation signal acquisition section 60. FIG.

The A/D converter 122 generates a digital evaluation signal Sa6 by analog-digital converting the evaluation signal Sa5 indicating the analog evaluation voltage. The digital evaluation signal Sa6 is a digital signal that indicates the value of the evaluation voltage based on the evaluation signal Sa5. The A/D converter 122 may also be considered to be included in the components of the evaluation signal acquisition section 60 . Digital evaluation signal Sa6 is transmitted to MPU20. At this time, the digital evaluation signal Sa6 may be transmitted from the driver IC 10 to the MPU 20 by SPI communication. However, a dedicated terminal for transmitting the digital evaluation signal Sa6 may be provided as an external terminal of the driver IC10.

In the configuration of FIG. 6 , the MPU 20 has the function of the wear determining section 70 . That is, the MPU 20 holds a predetermined judgment voltage value, and compares the evaluation voltage value (that is, the magnitude of the evaluation voltage) indicated by the digital evaluation signal Sa6 with the judgment voltage value. When the evaluation voltage value indicated by the digital evaluation signal Sa6 is equal to or higher than the judgment voltage value under the condition that the motor 40 is driven under the continuous reverse energization condition, the MPU 20 determines that the brush wear state is the good brush state. , and when the value of the evaluation voltage indicated by the digital evaluation signal Sa6 is smaller than the determination voltage value, it is determined that the worn state of the brush belongs to the defective brush state.

Further, in order to suppress erroneous determination due to noise, the high frequency component of the evaluation signal Sa5 is reduced between the amplifier circuit composed of the operational amplifier 121 and the resistors 123 and 124 and the A/D converter 122. A low pass filter may be provided. Alternatively, the function of the low-pass filter may be provided to the amplifier circuit or MPU 20 .

In the configuration of FIG. 6, the voltage _VDS of the output transistor M[3] is used as the evaluation voltage, but the voltage _VDS of the output transistor M[2] is used instead of the voltage _VDS of the output transistor M[3]. It may be used as an evaluation voltage.

Further, even when the motor 40 is driven under the reverse PWM energization condition, the method of Example EX1_3 can be applied. However, in this case, an averaging circuit (not shown) that generates a temporal average voltage of the voltage V _DS of the output transistor M[2] or M[3] is added to the driver IC 10 to indicate the average voltage. A signal or a signal indicating an amplified voltage of the average voltage may be input to the A/D converter 122 as the evaluation voltage Sa5. Also, the duty of the PWM signal at this time is set to a certain duty (because the average voltage value compared with the determination voltage value depends on the duty). An amplifier circuit composed of the operational amplifier 121 and resistors 123 and 124 may be provided with the function of the averaging circuit.

Also, the resistors 123 and 124 may be provided within the driver IC 10 . The amplification factor of the amplifier circuit including the operational amplifier 121 is arbitrary, and may be one. When the amplification factor is 1, the resistors 123 and 124 are not required and the operational amplifier 121 may form a voltage follower.

[Example EX1_4]
Example EX1_4 will be described. In the embodiment EX1_3, the configuration adapted only to the reverse rotation of the motor 40 was shown, but the driver IC 10 may be configured to be adapted to the forward rotation of the motor 40 as a matter of course. For example, the configuration shown in FIG. 7 can be adopted. FIG. 7 is a diagram showing a partial configuration of the driver IC 10 that contributes to the realization of operations related to the embodiment EX1_4, together with the output transistors M[1] to M[4] and the motor 40. As shown in FIG.

The driver IC 10 according to the embodiment EX1_4 is obtained by adding a multiplexer 125 to the driver IC 10 according to the embodiment EX1_3, and unless otherwise stated and there is no contradiction, the description of the embodiment EX1_3 is the same as that of the embodiment EX1_3. It also applies to EX1_4.

In the configuration of FIG. 7 according to the embodiment EX1_4, the source connection terminal S[1] to which the drain voltage of the output transistor M[3] is applied or the source connection terminal S[2] to which the drain voltage of the output transistor M[4] is applied is the multiplexer. 125 to the non-inverting input terminal of operational amplifier 121 . Control logic 11 controls the connection state of multiplexer 125 . That is, when the motor 40 is rotating in the reverse direction, the terminal S[1] is connected to the non-inverting input terminal of the operational amplifier 121, and when the motor 40 is rotating in the forward direction, the operational amplifier 121 is connected to the non-inverting input terminal. Control logic 11 controls multiplexer 125 such that terminal S[2] is connected to the input terminal. When the motor 40 is being rotated in reverse refers to when the motor 40 is driven under the reverse continuous energization condition or the reverse PWM energization condition. It refers to when the motor 40 is driven under reverse PWM energization conditions.

An amplifier circuit composed of operational amplifier 121 and resistors 123 and 124 amplifies the voltage _VDS of output transistor M[3] or M[4] and outputs the amplified output transistor M[3] or M[4]. voltage V _DS appears at the output terminal of operational amplifier 121 . When the motor 40 is reversed, the amplified voltage VDS of the output transistor M[3] appears at the output terminal of the operational amplifier 121 as an evaluation voltage, and a signal indicating the evaluation voltage functions as the evaluation signal _Sa5 . When the motor 40 is rotating forward, the amplified voltage VDS of the output transistor M[4] appears at the output terminal of the operational amplifier 121 as an evaluation voltage, and a signal indicating the evaluation voltage functions as an evaluation signal _Sa5 . . In the configuration of FIG. 7, a circuit that generates and propagates the evaluation signal Sa5, including the operational amplifier 121, the resistors 123 and 124, and the multiplexer 125, can be considered to constitute the evaluation signal acquisition section 60. FIG.

As described in the embodiment EX1_3, the A/D converter 122 generates the digital evaluation signal Sa6 by analog-digital converting the evaluation signal Sa5 indicating the analog evaluation voltage. Hereinafter, for convenience of explanation, the signals Sa5 and Sa6 obtained when the motor 40 is rotated forward will be referred to by symbols "Sa5_F" and "Sa6_F", respectively, and the signals obtained when the motor 40 is rotated reversely. Sa5 and Sa6 are referenced by the symbols "Sa5_R" and "Sa6_R" respectively.

In the configuration of FIG. 7 , the MPU 20 has the function of the wear determining section 70 . That is, the MPU 20 holds a predetermined determination voltage value, and compares the evaluation voltage value (that is, the magnitude of the evaluation voltage) indicated by the digital evaluation signal Sa6_F or Sa6_R with the determination voltage value. Then, when the value of the evaluation voltage indicated by the digital evaluation signal Sa6_F or Sa6_R is equal to or higher than the determination voltage value, the MPU 20 determines that the brush wear state belongs to the good brush state, and responds to the digital evaluation signal Sa6_F or Sa6_R. is smaller than the determination voltage value, it is determined that the worn state of the brush belongs to the defective brush state.

In the configuration of FIG. 7, the voltage V _DS of the output transistor M[4] is used as the evaluation voltage during normal rotation _. may be used as the _evaluation voltage. A similar modification at the time of reverse rotation is as described in Example EX1_3.

FIG. 7 basically shows a configuration adapted when the motor 40 is driven under the reverse rotation continuous energization condition or the forward rotation continuous energization condition. The configuration shown in Example EX1_4 can be used when the motor 40 is driven under the normal rotation PWM energization condition. However, in this case, an averaging circuit (not shown) for generating a temporal average voltage of the voltage V _DS of the output transistor M[i] through which the motor current flows is added to the driver IC 10, and a signal indicating the average voltage is added. Alternatively, a signal indicating the amplified voltage of the average voltage may be input to the A/D converter 122 as the evaluation voltage Sa5. Also, the duty of the PWM signal at this time is set to a certain duty (because the average voltage value compared with the determination voltage value depends on the duty). An amplifier circuit composed of the operational amplifier 121 and resistors 123 and 124 may be provided with the function of the averaging circuit.

In the configuration of FIG. 7, the circuit for generating the evaluation signal Sa5_F and the circuit for generating the evaluation signal Sa5_R are configured by a common circuit. You can do it. In this case, a multiplexer may be arranged between the circuit for generating the value signal Sa5_F and the circuit for generating the evaluation signal Sa5_R and the A/D converter 122 .

[Example EX1_5]
Example EX1_5 will be described. In Example EX1_5, the configuration (FIG. 7) shown in Example EX1_4 is used. Also, as shown in FIG. 8A, the MPU 20 is provided with a memory 21 (holding unit) which is a non-volatile memory. However, the memory 21 may be a memory externally connected to the MPU 20 .

The MPU 20 writes the reference voltage value Pa[t1] based on the digital evaluation signal Sa6 obtained at the timing t1 to the memory 21 at a certain timing t1 or immediately after the timing t1. The reference voltage value Pa[t1] written here is the reference voltage value Pa[t1]_F based on the signal Sa6_F[t1], which is the digital evaluation signal Sa6_F at timing t1, or the digital evaluation signal Sa6_R at timing t1. It is a reference voltage value Pa[t1]_R based on a certain signal Sa6_R[t1] (see FIG. 8B).

After that, at timing t2, the digital evaluation signal Sa6_F is obtained as the signal Sa6_F[t2], or the digital evaluation signal Sa6_R is obtained as the signal Sa6_R[t2]. The value of the evaluation voltage indicated by the signal Sa6_F[t2] (that is, the value of the evaluation voltage at the timing t2 when the motor 40 is rotating forward) is represented by the comparative voltage value Pa[t2]_F, and the signal Sa6_R[t2] ] (that is, the value of the evaluated voltage at the timing t2 when the motor 40 is rotating in reverse) is represented by the comparative voltage value Pa[t2]_R.

The timing t1 may be any timing, but it is preferable to be the timing immediately after the motor 40 is installed in the motor drive system 1 (the timing when there is no or almost no brush wear). Timing t2 is an arbitrary timing after timing t1. Both the reference voltage values Pa[t1]_F and Pa[t1]_R may be stored in the memory 21 . In this case, t1 is interpreted as a concept having a time width, and the signals Sa6_F[t1] and Sa6_R[t1] that are the sources of the reference voltage values Pa[t1]_F and Pa[t1]_R are obtained at different times. shall be

The reference voltage value Pa[t1]_F is determined based on the value of the evaluation voltage indicated by the signal Sa6_F[t1] (that is, the value of the evaluation voltage at timing t1 when the motor 40 is rotating forward; the initial value). It has a value that is lower by the voltage value (see FIG. 8(c)). After obtaining the comparative voltage value Pa[t2]_F at timing t2 (that is, the value of the evaluated voltage at timing t2 when the motor 40 is rotating forward), the MPU 20 obtains the comparative voltage value Pa[t2]_F as a reference. It is compared with the voltage value Pa[t1]_F, and if the comparative voltage value Pa[t2]_F is equal to or greater than the reference voltage value Pa[t1]_F, it is determined that the brush wear condition belongs to the good condition of the brush, and the comparative voltage value Pa If [t2]_F is smaller than the reference voltage value Pa[t1]_F, it is determined that the brush wear state belongs to the brush failure state.

Alternatively, the reference voltage value Pa[t1]_F is the value of the evaluation voltage indicated by the signal Sa6_F[t1] (that is, the value of the evaluation voltage at timing t1 when the motor 40 is rotating forward; the initial value) itself. It can be. In this case, the MPU 20 obtains the comparative voltage value Pa[t2]_F (that is, the value of the evaluated voltage at the timing t2 when the motor 40 is rotating forward) at the timing t2, and then obtains the comparative voltage value Pa[t2] _F is compared with the reference voltage value Pa[t1]_F, and if the comparison voltage value Pa[t2]_F is smaller than the reference voltage value Pa[t1]_F by a predetermined judgment voltage value or more, the worn state of the brush belongs to the brush failure state. Otherwise, it is determined that the worn state of the brush belongs to the good state of the brush.

The reference voltage value Pa[t1]_R is a predetermined judgment voltage from the value of the evaluation voltage indicated by the signal Sa6_R[t1] (that is, the value of the evaluation voltage at the timing t1 when the motor 40 is rotating in reverse; the initial value). It has a lower value by the value. After acquiring the comparative voltage value Pa[t2]_R at timing t2 (that is, the value of the evaluated voltage at timing t2 when the motor 40 is rotating in reverse), the MPU 20 converts the comparative voltage value Pa[t2]_R to the reference voltage. It is compared with the value Pa[t1]_R, and if the comparative voltage value Pa[t2]_R is equal to or higher than the reference voltage value Pa[t1]_R, it is determined that the brush wear state belongs to the good state of the brush, and the comparative voltage value Pa[t1]_R If t2]_R is smaller than the reference voltage value Pa[t1]_R, it is determined that the brush wear state belongs to the brush failure state.

Alternatively, the reference voltage value Pa[t1]_R is the value of the evaluation voltage indicated by the signal Sa6_R[t1] (that is, the value of the evaluation voltage at the timing t1 when the motor 40 is rotating in reverse; the initial value). can be In this case, the MPU 20 obtains the comparative voltage value Pa[t2]_R at the timing t2 (that is, the value of the evaluated voltage at the timing t2 when the motor 40 is rotating in reverse), and then obtains the comparative voltage value Pa[t2]_R is compared with the reference voltage value Pa[t1]_R, and if the comparison voltage value Pa[t2]_R is smaller than the reference voltage value Pa[t1]_R by a predetermined judgment voltage value or more, the worn state of the brush belongs to the brush failure state. Otherwise, it is determined that the wear condition of the brush belongs to the good condition of the brush.

Thus, in the embodiment EX1_5, the magnitude of the evaluation voltage (that is, the magnitude of the voltage _DS of the output transistor M[i] when the motor current is supplied to the motor 40 through the output transistor M[i]) is Noting that it decreases as the wear of the brush progresses, the reference voltage value (Pa[t1]_F, Pa[t1]_R) based on the magnitude of the evaluation voltage at timing t1 is set as an initial value. , is held in the memory 21 . Then, by comparing the magnitude of the evaluation voltage (Pa[t2]_F, Pa[t2]_R) at timing t2 thereafter with the reference voltage value, it is determined whether or not the brush wear state belongs to the brush failure state. judge.

<<Second Embodiment>>
A second embodiment according to the present invention will be described. In the second embodiment, a current sensor for measuring the motor current is used, and a signal indicating the magnitude of the motor current measured by the current sensor under predetermined energization conditions is used as the evaluation signal. As the degree of brush wear increases, the motor current relatively decreases, so the degree of wear can be determined from the magnitude of the motor current.

The second embodiment includes the following examples EX2_1 to EX2_3. In Examples EX2_1 to EX2_3, specific examples of determining wear based on the motor current will be described.

[Example EX2_1]
Example EX2_1 will be described. FIG. 9 is a diagram showing a partial configuration of the driver IC 10 that contributes to the realization of operations related to the embodiment EX2_1, together with the output transistors M[1] to M[4] and the motor 40. As shown in FIG. A sense resistor R _SNS is inserted between the node where the sources of the output transistors M[3] and M[4] are connected in common and the ground, and the motor current flows through the sense resistor R _SNS . A current sensor is formed by the sense resistor R _SNS . However, as long as the sense resistor R _SNS is inserted in series on the current path through which the motor current flows, the placement position of the sense resistor R _SNS may be arbitrary (the same applies to embodiments EX2_2 and EX2_3 described later). However, since the source potentials of output transistors M[3] and M[4] do not switch between the potential of power supply voltage VPWR and ground potential like the potentials at nodes NDa and NDb, output transistors M[3] and M[4] ] and the ground is preferable for improving the accuracy of current detection (switching noise is less _likely to be mixed), and it is also preferable because the subsequent stage circuit can be formed with low voltage elements. It should be noted that the first embodiment can also be understood as an embodiment in which the on-resistance of the output transistor M[i] is used as the sense resistor _RSNS .

In the embodiment EX2_1, the driver IC 10 is provided with a preprocessing section 141, a comparator 142, and a voltage source 143 that generates a predetermined judgment voltage _VREF3 . The judgment voltage _VREF3 has a predetermined positive DC voltage value.

A signal Sb0 indicating the voltage across the sense resistor R _SNS (that is, the voltage drop occurring across the sense resistor R _SNS in accordance with the motor current) is input to the preprocessing section 141 through two external terminals provided on the driver IC 10. be. In the configuration of FIG. 9, the two external terminals are the source connection terminal _SCOM and the ground terminal GND. The preprocessing unit 141 includes a filter circuit for reducing noise in the signal Sb0, an amplifier circuit for amplifying the signal Sb0, an absolute value circuit for obtaining the absolute value of the amplified signal Sb0, and the like. Under predetermined energization conditions, the preprocessing unit 141 generates an evaluation signal Sb1, which is a voltage signal indicating the magnitude of the motor current, based on the signal Sb0. It is assumed that the voltage value of the evaluation signal Sb1 and the magnitude of the motor current are directly proportional to each other, and that the voltage value of the evaluation signal Sb1 monotonically increases as the magnitude of the motor current increases. In the configuration of FIG. 9, it can be considered that the preprocessing section 141 that generates the evaluation signal Sb1 constitutes the evaluation signal acquisition section 60. FIG. It is also possible to understand that the sense resistor R _SNS is also included in the components of the evaluation signal acquisition section 60 .

In the comparator 142, the evaluation signal Sb1 is input to the inverting input terminal, and the determination voltage _VREF3 is applied to the non-inverting input terminal. Therefore, the comparator 142 outputs the determination signal Sb2 according to the magnitude relationship between the voltage of the evaluation signal Sb1 and the determination voltage _VREF3 . As will become apparent from the later description, the value of the determination voltage _VREF3 represents the boundary determination current value for distinguishing the degree of abrasion of the brush.

When the voltage of the evaluation signal Sb1 is higher than the determination voltage _VREF3 (in other words, when the magnitude of the motor current is greater than the determination current value indicated by the determination voltage _VREF3 ), the comparator 142 outputs a low-level determination signal. Sb2 is output, and when the voltage of the evaluation signal Sb1 is lower than the judgment voltage _VREF3 (in other words, when the magnitude of the motor current is smaller than the judgment current value indicated by the judgment voltage _VREF3 ), a high-level judgment signal Output Sb2. When the voltage of the evaluation signal Sb1 exactly matches the determination voltage _VREF3 , the level of the determination signal Sb2 becomes low level or high level.

In the configuration of FIG. 9 , the control logic 11 has the function of the wear determining section 70 . That is, the control logic 11 determines that the brush wear condition belongs to the good condition of the brush when the level of the determination signal Sb2 is low under the condition that the motor 40 is driven under a predetermined energization condition. is at a high level, it is determined that the worn state of the brush belongs to the defective brush state.

The voltage source 143 may be formed so that the value of the determination voltage V _REF3 is variable. In this case, the value of the determination voltage V _REF3 in the voltage source 143 is set based on an instruction from the MPU 20 via SPI communication. May be. By adjusting the determination voltage _VREF3 , it is possible to adjust the threshold for determining brush wear, making it possible to adapt to various types of motors.

In addition, in order to suppress erroneous determination due to noise, a low-pass filter that reduces the high frequency components of the determination signal Sb2 is provided between the comparator 142 and the control logic 11, and the determination signal Sb2 after the reduction is used. The wear state of the brush may be determined. This is not the case if the preprocessing unit 141 is sufficiently equipped with a high-frequency component reduction function.

The energization condition for obtaining the evaluation signal Sb1 and the energization condition for determining the wear state of the brush are basically the forward continuous energization condition or the reverse continuous energization condition. It may be an energized condition. However, when the evaluation signal Sb1 is obtained under the forward PWM energization condition or the reverse PWM energization condition, the preprocessing unit 141 is provided with a function of generating a temporal average voltage of the voltage across the sense resistor _RSNS . , the evaluation signal Sb1 may be generated based on the average voltage. Also, the duty of the PWM signal at this time is set to a certain duty (because the average voltage depends on the duty).

[Example EX2_2]
Example EX2_2 will be described. FIG. 10 is a diagram showing a partial configuration of the driver IC 10 that contributes to the realization of operations related to the embodiment EX2_2, together with the output transistors M[1] to M[4] and the motor 40. As shown in FIG. In Example EX2_1 (FIG. 9), in addition to preprocessing section 141, comparator 142 and voltage source 143 are provided in driver IC 10. In Example EX2_2 (FIG. 10), in addition to preprocessing section 141, Therefore, an A/D converter 145 is provided in the driver IC 10 instead of the comparator 142 and the voltage source 143 . Except for this point, the configuration according to the example EX2_1 and the configuration according to the example EX2_2 are common, and the description of the common parts will be omitted.

The A/D converter 145 generates a digital evaluation signal Sb3 by analog-digital converting the analog evaluation signal Sb1 representing the magnitude of the motor current. The digital evaluation signal Sb3 is a digital signal representing the value of the motor current. In Example EX2_2, the A/D converter 145 may also be considered to be included in the component of the evaluation signal acquisition section 60. FIG. Digital evaluation signal Sb3 is transmitted to MPU20. At this time, the digital evaluation signal Sb3 may be transmitted from the driver IC 10 to the MPU 20 through SPI communication. However, a dedicated terminal for transmitting the digital evaluation signal Sb3 may be provided as an external terminal of the driver IC10.

In the configuration of FIG. 10 , the MPU 20 has the function of the wear determining section 70 . That is, the MPU 20 holds a predetermined judgment current value, and compares the magnitude of the motor current indicated by the digital evaluation signal Sb3 with the judgment current value. When the magnitude of the motor current indicated by the digital evaluation signal Sb3 is equal to or greater than the determination current value in a situation where the motor 40 is driven under a predetermined energization condition, the MPU 20 determines that the brush wear state is the good brush state. and when the magnitude of the motor current indicated by the digital evaluation signal Sb3 is smaller than the determination current value, it is determined that the brush wear state belongs to the brush failure state. The energization conditions here are forward continuous energization conditions or reverse continuous energization conditions, and can be forward rotation PWM energization conditions or reverse PWM energization conditions, as shown in Example EX2_1.

[Example EX2_3]
Example EX2_3 will be described. In Example EX2_3, the configuration (FIG. 10) shown in Example EX2_2 is used. Also, as shown in FIG. 11A, the MPU 20 is provided with a memory 21 (holding unit) which is a non-volatile memory. However, the memory 21 may be a memory externally connected to the MPU 20 .

At a certain timing t1 or immediately after timing t1, the MPU 20 writes the reference current value Pb[t1] based on the signal Sb3[t1], which is the digital evaluation signal Sb3 obtained at the timing t1, into the memory 21 (FIG. 11(b )reference). After that, at timing t2, the digital evaluation signal Sb3 is obtained as the signal Sb3[t2]. Signals Sb3[t1] and Sb3[t2] represent the magnitude of the motor current at timings t1 and t2, respectively. Also, the value of the motor current indicated by the signal Sb3[t2] is referred to as a comparison current value Pb[t2]. It is assumed that the motor 40 is driven under common energization conditions at timings t1 and t2. For example, at timings t1 and t2, the motor 40 is commonly driven under the forward rotation continuous energization condition, or is commonly driven under the reverse rotation continuous energization condition.

The timing t1 may be any timing, but it is preferable to be the timing immediately after the motor 40 is installed in the motor drive system 1 (the timing when there is no or almost no brush wear). Timing t2 is an arbitrary timing after timing t1.

The reference current value Pb[t1] has a value lower than the magnitude of the motor current indicated by the signal Sb3[t1] (that is, the magnitude of the motor current at timing t1; initial value) by a predetermined determination current value ( See FIG. 11(c)). After acquiring the relative current value Pb[t2] (that is, the magnitude of the motor current at timing t2) at timing t2, the MPU 20 compares the relative current value Pb[t2] with the reference current value Pb[t1], If the comparative current value Pb[t2] is equal to or greater than the reference current value Pb[t1], it is determined that the brush wear condition belongs to the good condition of the brush, and the comparative current value Pb[t2] is higher than the reference current value Pb[t1]. If it is smaller, it is determined that the worn state of the brush belongs to the defective brush state.

Alternatively, the reference current value Pb[t1] may be the magnitude of the motor current indicated by the signal Sb3[t1] (that is, the magnitude of the motor current at timing t1; initial value). In this case, the MPU 20 acquires the relative current value Pb[t2] (that is, the magnitude of the motor current at the timing t2) at timing t2, and then sets the relative current value Pb[t2] as the reference current value Pb[t1]. If the comparison current value Pb[t2] is smaller than the reference current value Pb[t1] by a predetermined determination current value or more, the brush wear state is determined to belong to the brush failure state. It is determined that the brush belongs to the good condition.

In this way, in Example EX2_3, attention is paid to the fact that the magnitude of the motor current under a predetermined energization condition decreases as the wear of the brush progresses. The current value (Pb[t1]) is stored in the memory 21 as an initial value. Then, by comparing the magnitude of the motor current (Pb[t2]) at subsequent timing t2 with the reference current value, it is determined whether or not the brush wear state belongs to the brush failure state.

<<Third Embodiment>>
A third embodiment according to the present invention will be described. In the third embodiment, the voltage across the terminals of the motor 40 (that is, the voltage between the nodes NDa and NDb) under predetermined energization conditions is treated as the evaluation voltage, and the signal indicating the evaluation voltage is used as the evaluation signal. As already mentioned, the voltage across motor 40 (ie, the voltage across nodes NDa and NDb) is referred to as the motor voltage.

As the degree of wear of the brushes increases, the contact resistance between the brushes and the commutator increases, and the motor voltage increases under given energization conditions. In the third embodiment, attention is paid to this characteristic, and wear determination is performed using the motor voltage.

The third embodiment includes the following Examples EX3_1 to EX3_3. In Examples EX3_1 to EX3_3, specific examples of determining wear based on motor voltage will be described.

[Example EX3_1]
Example EX3_1 will be described. FIG. 12 is a diagram showing a partial configuration of the driver IC 10 that contributes to the realization of operations related to the embodiment EX3_1, together with the output transistors M[1] to M[4] and the motor 40. As shown in FIG. In the embodiment EX3_1, the driver IC 10 is provided with a preprocessing section 161, a comparator 162, and a voltage source 163 that generates a predetermined judgment voltage _VREF4 . The judgment voltage V _REF4 has a predetermined positive DC voltage value.

A signal Sc0 indicating the motor voltage is input to the preprocessing unit 161 by being applied between the terminals S[1] and S[2]. The preprocessing unit 161 includes a filter circuit for reducing noise in the signal Sc0, an amplifier circuit for amplifying the signal Sc0, an absolute value circuit for obtaining the absolute value of the amplified signal Sc0, and the like. Under predetermined energization conditions, the preprocessing unit 161 generates an evaluation signal Sc1, which is a voltage signal indicating the magnitude of the motor voltage, based on the signal Sc0. Assume that the voltage value of the evaluation signal Sc1 and the magnitude of the motor voltage are in a directly proportional relationship, and that the voltage value of the evaluation signal Sc1 monotonically increases as the magnitude of the motor voltage increases. In the configuration of FIG. 12, it can be considered that the preprocessing section 161 that generates the evaluation signal Sc1 constitutes the evaluation signal acquisition section 60. FIG.

In the comparator 162, the evaluation signal Sc1 is input to the non-inverting input terminal, and the determination voltage _VREF4 is applied to the inverting input terminal. Therefore, the comparator 162 outputs the determination signal Sc2 corresponding to the level relationship between the voltage of the evaluation signal Sc1 and the determination voltage _VREF4 . As will be apparent from the later description, the value of the determination voltage _VREF4 represents a boundary determination voltage value for distinguishing the degree of abrasion of the brush.

When the voltage of the evaluation signal Sc1 is lower than the determination voltage _VREF4 (in other words, when the magnitude of the motor voltage is smaller than the determination voltage value indicated by the determination voltage _VREF4 ), the comparator 162 outputs a low-level determination signal. Sc2 is output, and when the voltage of the evaluation signal Sc1 is higher than the judgment voltage V _REF4 (in other words, when the magnitude of the motor voltage as the evaluation voltage is larger than the judgment voltage value indicated by the judgment voltage V _REF4 ), the high A level determination signal Sc2 is output. When the voltage of the evaluation signal Sc1 exactly matches the determination voltage _VREF4 , the level of the determination signal Sc2 becomes low level or high level.

In the configuration of FIG. 12 , the control logic 11 has the function of the wear determining section 70 . That is, the control logic 11 determines that the brush wear condition belongs to the good condition of the brush when the level of the determination signal Sc2 is low under the condition that the motor 40 is driven under the predetermined energization condition. is at a high level, it is determined that the worn state of the brush belongs to the defective brush state.

The voltage source 163 may be formed so that the value of the determination voltage V _REF4 is variable. In this case, the value of the determination voltage V _REF4 in the voltage source 163 is set based on an instruction from the MPU 20 via SPI communication. May be. By adjusting the determination voltage _VREF4 , it is possible to adjust the threshold for determining brush wear, making it possible to adapt to various types of motors.

Further, in order to suppress erroneous determination due to noise, a low-pass filter is provided between the comparator 162 and the control logic 11 to reduce the high frequency components of the determination signal Sc2, and the reduced determination signal Sc2 is used to The wear state of the brush may be determined. This is not the case if the preprocessing unit 161 is sufficiently equipped with a high-frequency component reduction function.

The energization condition for obtaining the evaluation signal Sc1 and the energization condition for determining the wear state of the brush are basically the forward rotation continuous energization condition or the reverse rotation continuous energization condition, but the forward rotation PWM energization condition or the reverse PWM energization condition. It may be an energized condition. However, when obtaining the evaluation signal Sc1 under the forward rotation PWM energization condition or the reverse rotation PWM energization condition, the preprocessing unit 161 is provided with a function of generating a temporal average voltage of the motor voltage. It is preferable to generate the evaluation signal Sc1. Also, the duty of the PWM signal at this time is set to a certain duty (because the average voltage depends on the duty).

[Example EX3_2]
Example EX3_2 will be described. FIG. 13 is a diagram showing a partial configuration of the driver IC 10 that contributes to the realization of operations related to the embodiment EX3_2, together with the output transistors M[1] to M[4] and the motor 40. As shown in FIG. In Example EX3_1 (FIG. 12), in addition to preprocessing section 161, comparator 162 and voltage source 163 are provided in driver IC 10. In Example EX3_2 (FIG. 13), in addition to preprocessing section 161, Therefore, an A/D converter 165 is provided in the driver IC 10 instead of the comparator 162 and the voltage source 163 . Except for this point, the configuration according to the example EX3_1 and the configuration according to the example EX3_2 are common, and the description of the common parts is omitted.

The A/D converter 165 generates a digital evaluation signal Sc3 by analog-digital converting the analog evaluation signal Sc1 representing the magnitude of the motor voltage. The digital evaluation signal Sc3 is a digital signal representing the value of the motor voltage. In Example EX3_2, the A/D converter 165 may also be considered to be included in the component of the evaluation signal acquisition section 60. FIG. The digital evaluation signal Sc3 is transmitted to the MPU20. At this time, the digital evaluation signal Sc3 may be transmitted from the driver IC 10 to the MPU 20 by SPI communication. However, a dedicated terminal for transmitting the digital evaluation signal Sc3 may be provided as an external terminal of the driver IC10.

In the configuration of FIG. 13 , the MPU 20 has the function of the wear determining section 70 . That is, the MPU 20 holds a predetermined judgment voltage value, and compares the magnitude of the motor voltage indicated by the digital evaluation signal Sc3 with the judgment voltage value. When the motor voltage indicated by the digital evaluation signal Sc3 is equal to or less than the judgment voltage value under the condition that the motor 40 is driven under a predetermined energization condition, the MPU 20 determines that the brush wear state is the good brush state. , and when the magnitude of the motor voltage indicated by the digital evaluation signal Sc3 is greater than the determination voltage value, it is determined that the brush wear state belongs to the brush failure state. The energization conditions here are forward continuous energization conditions or reverse continuous energization conditions, and can be forward rotation PWM energization conditions or reverse PWM energization conditions, as shown in Example EX3_1.

[Example EX3_3]
Example EX3_3 will be described. In Example EX3_3, the configuration (FIG. 13) shown in Example EX3_2 is used. Also, as shown in FIG. 14A, the MPU 20 is provided with a memory 21 (holding unit) which is a non-volatile memory. However, the memory 21 may be a memory externally connected to the MPU 20 .

At a certain timing t1 or immediately after the timing t1, the MPU 20 writes the reference voltage value Pc[t1] based on the signal Sc3[t1], which is the digital evaluation signal Sc3 obtained at the timing t1, into the memory 21 (Fig. 14(b )reference). After that, at timing t2, the digital evaluation signal Sc3 is acquired as the signal Sc3[t2]. Signals Sc3[t1] and Sc3[t2] represent the magnitude of the motor voltage at timings t1 and t2, respectively. Also, the value of the motor voltage indicated by the signal Sc3[t2] is referred to as a comparison voltage value Pc[t2]. It is assumed that the motor 40 is driven under common energization conditions at timings t1 and t2. For example, at timings t1 and t2, the motor 40 is commonly driven under the forward rotation continuous energization condition, or is commonly driven under the reverse rotation continuous energization condition.

The timing t1 may be any timing, but it is preferable to be the timing immediately after the motor 40 is installed in the motor drive system 1 (the timing when there is no or almost no brush wear). Timing t2 is an arbitrary timing after timing t1.

The reference voltage value Pc[t1] has a value higher than the magnitude of the motor voltage indicated by the signal Sc3[t1] (that is, the magnitude of the motor voltage at timing t1; initial value) by a predetermined judgment voltage value ( See FIG. 14(c)). After acquiring the comparative voltage value Pc[t2] (that is, the magnitude of the motor voltage at timing t2) at timing t2, the MPU 20 compares the comparative voltage value Pc[t2] with the reference voltage value Pc[t1], If the comparative voltage value Pc[t2] is equal to or less than the reference voltage value Pc[t1], it is determined that the brush wear condition belongs to the good condition of the brush, and the comparative voltage value Pc[t2] is higher than the reference voltage value Pc[t1]. If it is large, it is determined that the worn state of the brush belongs to the defective brush state.

Alternatively, the reference voltage value Pc[t1] may be the magnitude of the motor voltage indicated by the signal Sc3[t1] (that is, the magnitude of the motor voltage at timing t1; initial value). In this case, the MPU 20 acquires the comparative voltage value Pc[t2] (that is, the magnitude of the motor voltage at the timing t2) at timing t2, and then sets the comparative voltage value Pc[t2] as the reference voltage value Pc[t1]. If the comparison voltage value Pc[t2] is greater than the reference voltage value Pc[t1] by a predetermined determination voltage value or more, the brush wear state is determined to belong to the brush failure state. It is determined that the brush belongs to the good condition.

In this way, in Example EX3_3, attention is paid to the fact that the magnitude of the motor voltage under predetermined energization conditions decreases as the wear of the brush progresses. The voltage value (Pc[t1]) is stored in the memory 21 as an initial value. Then, by comparing the magnitude of the motor voltage (Pc[t2]) at subsequent timing t2 with the reference voltage value, it is determined whether or not the brush wear state belongs to the brush failure state.

<<Fourth Embodiment>>
A fourth embodiment according to the present invention will be described. Determination by the control logic 11 or the MPU 20 that the brush wear state belongs to the brush failure state is referred to as brush failure determination. When the control logic 11 determines that the state of brush wear belongs to the defective state of the brush, the MPU 20 notifies it. The MPU 20 can cause the external connection device 30 functioning as a notification section to perform a predetermined wear notification when the brush failure is determined using any of the methods described above. The wear notification is for a person to be notified, and the person to be notified includes a user and an administrator of the motor drive system 1 . As will be described later, when the motor drive system 1 is installed in a vehicle, the persons to be notified include the passengers (including the driver) of the vehicle and the manager of the vehicle. It may include humans performing repairs and the like.

As long as the person to be notified can perceive that the brush failure determination has been made, the manner of wear notification is arbitrary. For example, when the external connection device 30 includes a light-emitting element, the light-emitting element may emit light in a predetermined light emission pattern in the wear notification. Alternatively, if the external connection device 30 includes a display device such as a liquid crystal display, a predetermined image for wear notification may be displayed on the display device for wear notification.

By performing the wear notification, the person to be notified can easily know the maintenance timing of the motor 40 .

[Fifth embodiment]
A fifth embodiment according to the present invention will be described. Although a configuration example in which a DC motor is driven by a full bridge circuit (H bridge circuit) has been described above, the circuit configuration for driving a DC motor is not limited to this. For example, as shown in FIG. 15, a circuit configuration for driving four motors 40[1] to 40[4] may be adopted as the motor 40. FIG.

In the configuration of FIG. 15, for each integer i of 1 or more and 4 or less, a motor 40[i], which is a DC motor with a brush, is inserted in series between the terminal to which the power supply voltage VPWR is applied and the drain of the output transistor M[i]. be done. The sources of the output transistors M[1] to M[4] are grounded and connected to the source connection terminal _SCOM .

The gate drive circuit 12 controls the states of the output transistors M[1] to M[4] by individually controlling the gate voltages VG[1] to VG[4] under the control of the control logic 11, Thereby, the motors 40[1] to 40[4] can be driven individually.

The brush wear condition may be determined individually for the motors 40[1] to 40[4]. That is, the motor current is supplied to the motor 40[i] through the output transistor M[i] under the continuous energization condition in which the output transistor M[i] is continuously turned on or the PWM energization condition in which the output transistor M[i] is switchingly driven. , and based on the voltage V _DS of the output transistor M[i] at that time, the motor current (the current flowing through the motor 40[i]), or the motor voltage (the voltage across the terminals of the motor 40[i]), the motor 40 The wear state of the brush [i] can be determined, and this determination can be made for each motor. Any method shown in the first to third embodiments can be used for this determination.

When the method of the first embodiment is _applied to the configuration of FIG. 15, a processing circuit (for example, in the configuration of FIG. equivalent) may be provided in the driver IC 10 for each output transistor, or only one processing circuit may be provided, and the single processing circuit may be used in a time-sharing manner to control the output transistors M[1] to M[4]. You can share it with
Similarly, when applying the method of the second embodiment to the configuration of FIG. equivalent) may be provided in the driver IC 10 for each output transistor, or only one processing circuit may be provided, and the single processing circuit may be used in a time-sharing manner to control the output transistors M[1] to M[4]. You can share it with
Similarly, when applying the method of the third embodiment to the configuration of FIG. equivalent) may be provided in the driver IC 10 for each output transistor, or only one processing circuit may be provided, and the single processing circuit may be used in a time-sharing manner to control the output transistors M[1] to M[4]. You can share it with

Further, the method shown in the fourth embodiment may be applied to each of the motors 40[1] to 40[4], and the wear notification may be performed for each motor.

[Sixth Embodiment]
A sixth embodiment according to the present invention will be described. As shown in FIG. 16, a motor drive system 310 according to an embodiment of the present invention can be mounted on a vehicle 300 such as an automobile. The motor drive system 310 may be the same as the motor drive system 1 shown in FIG. 1, or may be the motor drive system 1 shown in FIG. 1 with the modifications shown in the fifth embodiment (see FIG. 15) applied. It's fine.

The motor 40 in the motor drive system 310 is mounted on the vehicle 300 and used for any vehicle part that requires a motor, such as cooling fans, air conditioners, power windows and sliding doors. .

For example, when the power window is driven by the motor 40, the power supplied to the motor 40 is relatively reduced by the forward or reverse PWM drive method immediately after the power window starts to be driven and immediately before the end of the power window, thereby suppressing the movement of the power window. Under the control of the MPU 20, the power window is driven slowly, and the power window is moved quickly by relatively increasing the power supplied to the motor 40 by a forward rotation or reverse rotation continuous driving method in the intermediate portion of the power window driving. is done in In such a usage pattern, it is preferable to acquire the above-described evaluation signal and determine the state of wear of the brush during a section in which the motor 40 is driven by the forward or reverse continuous drive method.

Also, the motor drive system 310 may include a plurality of sets of the driver IC 10, the output transistors M[1] to M[4], and the motor 40. At this time, the MPU 20 is provided in the plurality of sets. It may collectively manage and recognize the wear states of the brushes of the plurality of motors 40 . Regarding this, the plurality of motors 40 will be referred to as the first to n-th motors 40 for additional explanation. n is an arbitrary integer of 2 or more.

In the motor drive system 310, the wear state of the brushes of the first to n-th motors 40 is determined individually by the method described above, and the MPU 20 determines whether the brush wear state of the motor 40 is good for each motor 40. It recognizes which one of the state and the brush failure state it belongs to and stores it in the memory 21 . For example, when the brush failure determination is made only for the first and second motors 40, the MPU 20 can cause the external connection device 30 to perform wear notification specifying the first and second motors 40. can. For example, when the first and second motors 40 are a blower motor and a wind direction switching motor in an air conditioner as a vehicle part, the characters "air conditioner error" are displayed on the display device as the external connection device 30. Alternatively, more detailed wear notification may be performed by displaying the characters "air conditioner blower error" and "air conditioner wind direction changer error" on the display device.

After that, when the vehicle 300 is brought to a dealer who investigates or repairs the vehicle 300, the trouble investigator of the dealer can easily know which motor is malfunctioning by referring to the wear notification. can be done. Further, by connecting a tester to a dedicated terminal provided on the vehicle 300 and reading out the data held in the memory 21, the failure investigator can know in detail which motor has the problem. , it is possible to quickly replace the necessary motor 40 .

[Seventh Embodiment]
A seventh embodiment according to the present invention will be described. In the seventh embodiment, applied techniques and modified techniques applicable to the basic embodiment and the first to sixth embodiments described above will be described.

The output transistors M[1] to M[4] may be built in the driver IC10.

In each of the above-described embodiments, the wear state of the brushes of the motor 40 is classified and determined in two stages based on the evaluation signal that depends on the magnitude of the motor current. The state may be classified and determined in three stages or more.

For any signal or voltage, the relationship between high and low levels may be reversed without departing from the spirit of the discussion above.

The output transistors M[i] may be transistors of a type other than MOSFETs, and may be configured as, for example, bipolar transistors, junction FETs (Field Effect Transistors), or IGBTs (Insulated Gate Bipolar Transistors). Any transistor has a first electrode, a second electrode and a control electrode. In a FET, one of the first and second electrodes is the drain and the other is the source, and the control electrode is the gate. In an IGBT, one of the first and second electrodes is the collector and the other is the emitter, and the control electrode is the gate. In a bipolar transistor not belonging to an IGBT, one of the first and second electrodes is the collector and the other is the emitter and the control electrode is the base.

[Consideration of the Invention]
Consider the invention embodied in each of the above-described embodiments.

A motor driver device according to the present invention is a motor driver device for driving a DC motor with brushes, wherein the motor current is supplied to the DC motor through an output transistor. an evaluation signal acquisition unit that acquires an evaluation signal that depends on , and an abrasion judgment unit that judges the abrasion state of the brush of the DC motor based on the evaluation signal.

As a result, it becomes possible to determine the state of wear of the brushes of the DC motor with brushes well, and it is also possible to inform the outside of the determination result. As a result, it is expected that the administrator or the like will no longer need to frequently check the state of wear of the brush.

In each of the embodiments described above, the components of the motor driver device according to the present invention include at least the driver IC 10 and may also include the MPU 20 . It is also possible to understand that the output transistor M[i] or the external connection device 30 is also included in the components of the motor driver device according to the present invention.

The embodiments of the present invention can be appropriately modified in various ways within the scope of the technical idea indicated in the scope of claims. The above embodiments are merely examples of the embodiments of the present invention, and the meanings of the terms of the present invention and each constituent element are not limited to those described in the above embodiments. The specific numerical values given in the above description are merely examples and can of course be changed to various numerical values.

1 Motor drive system 10 Driver IC
11 control logic 12 gate drive circuit 20 MPU
30 external connection device 40 motor 60 evaluation signal acquisition unit 70 wear determination unit M[1] to M[4] output transistor

Claims (5)

Driving a brushed DC motor connected to a full bridge circuit comprising a first transistor and a third transistor connected in series with each other and a second transistor and a fourth transistor connected in series with each other In a motor driver device for
the DC motor is connected between a first connection node between the first transistor and the third transistor and a second connection node between the second transistor and the fourth transistor;
an evaluation signal acquisition unit that acquires an evaluation signal that depends on the magnitude of the motor current under a predetermined energization condition in which the DC motor is supplied with the motor current through any one of the first to fourth transistors ;
a wear determination unit that determines a wear state of the brush of the DC motor based on the evaluation signal;
The evaluation signal acquisition unit can acquire a signal indicating a voltage between the first electrode and the second electrode of the third transistor or a voltage between the first electrode and the second electrode of the second transistor as the first evaluation signal. and a signal indicating the voltage between the first electrode and the second electrode of the fourth transistor or the voltage between the first electrode and the second electrode of the first transistor can be obtained as a second evaluation signal,
The wear state of the brush is classified into a first state in which the wear of the brush is relatively small and a second state in which the wear of the brush is relatively large,
The wear determination section uses either one of the first evaluation signal and the second evaluation signal as an evaluation voltage according to the rotation direction of the DC motor, and the magnitude of the evaluation voltage is smaller than a predetermined evaluation voltage value. when the state of wear of the brush is determined to belong to the second state.
, motor driver device. When the motor current flows from the first connection node to the second connection node to rotate the direct-current motor in the first rotation direction, the wear determination unit uses the second evaluation signal as the evaluation voltage. using
When the DC motor rotates in a second rotation direction opposite to the first rotation direction due to the motor current flowing from the second connection node to the first connection node, the wear determination unit determines the using the first evaluation signal as the evaluation voltage
The motor driver device according to claim 1. The determination voltage values are equal when the first evaluation signal is used as the evaluation voltage and when the second evaluation signal is used as the evaluation voltage.
3. The motor driver device according to claim 1 or 2. The wear determination unit uses the first value as the determination voltage value when the first evaluation signal is used as the evaluation voltage, and the wear determination unit as the determination voltage value when the second evaluation signal is used as the evaluation voltage. use a second value different from the first
3. The motor driver device according to claim 1 or 2. The wear determination unit causes the notification unit to perform a predetermined notification when determining that the wear state of the brush belongs to the second state.
The motor driver device according to any one of claims 1 to 4.

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