JP6935719B2 - DC motor ripple detector - Google Patents

Description

The present invention relates to a ripple detection device for a DC motor.

Conventionally, a DC motor that supplies a current (hereinafter referred to as "motor current") to a rotating armature while switching the energization direction between a brush and a commutator, a so-called DC brush motor, is known. In such a DC motor, the current ripple generated by the rotation of the rotating armature and the switching of the contact between the brush and the commutator is superimposed on the motor current. Therefore, in order to detect the rotation phase of the rotating armature (hereinafter, simply referred to as "rotation state"), the current ripple included in the motor current when the DC motor is driven is acquired and its singular point (for example, maximum point, minimum point). , Zero cross point, etc.) have been proposed for ripple detection devices for DC motors (for example, Patent Documents 1 and 2). The ripple detection device of the DC motor can realize simple detection of the rotational state of the DC motor by substituting for sensors such as an encoder, a resolver, and a Hall element.

Japanese Unexamined Patent Publication No. 2010-45953 Japanese Unexamined Patent Publication No. 2009-20726

By the way, such a DC motor ripple detection device converts a current ripple (motor current) at the time of driving a DC motor into a voltage via a shunt resistor, and further pulse-converts the converted current ripple to detect a rotating state. Since it is provided, only one DC motor can detect the rotating state. This is because when a plurality of DC motors are driven at the same time, the current ripples of the plurality of DC motors are superimposed on the shunt resistance of only one, and the pulse conversion of the current ripples of each DC motor becomes difficult. .. In other words, in order to monitor the current ripple of all DC motors with one shunt resistor, it is necessary to drive a plurality of DC motors individually at different timings (for example, progressive feed). In this case, it is inevitable to prolong the time required to complete the driving of all the DC motors.

An object of the present invention is to provide a DC motor ripple detection device capable of individually detecting the rotational state of a plurality of DC motors even if the plurality of DC motors are driven at the same time.

The ripple detection device of the DC motor that solves the above problems is connected in series to a plurality of parallel-connected DC motors having different ripple numbers per rotation, and a combined motor current obtained by synthesizing all the motor currents of the plurality of DC motors. Of the current detection unit for detecting the above, the first acquisition unit for acquiring the current ripple included in the combined motor current in a state where the plurality of DC motors are simultaneously driven, and the plurality of DC motors. A storage unit that individually stores current ripples corresponding to all rotation positions and rotation directions of the second DC motor, which is the DC motor other than the first DC motor, which is the DC motor, as current ripple data, and a plurality of the storage units. The estimated current included in the motor current of the first DC motor by subtracting all of the current ripple data in the corresponding rotation position and rotation direction from the acquired combined current ripple while simultaneously driving the DC motors of the above. Corresponding to the calculation unit that calculates the ripple, the first pulse generation unit that generates the first ripple pulse representing the rotation state of the first DC motor based on the estimated current ripple, and the current ripple data. It is provided with a second pulse generation unit that generates a second ripple pulse that represents the rotational state of the second DC motor.

According to this configuration, in a state where the plurality of DC motors are driven at the same time, the first ripple pulse is generated in the first pulse generation unit based on the estimated current ripple. On the other hand, each of the second ripple pulses is generated in the second pulse generation unit based on the corresponding current ripple data. Therefore, even if the plurality of DC motors are driven at the same time, the rotational state of the plurality of DC motors can be individually detected.

The ripple detection device of the DC motor is based on a second acquisition unit that acquires the current ripple included in the combined motor current in a state where the second DC motor is independently driven as a single current ripple, and the single current ripple. It is provided with an estimation unit that estimates the actual load of the second DC motor and a correction unit that individually corrects all current ripple data of the second DC motor based on the estimated load. The calculation unit calculates the estimated current ripple based on the corrected current ripple data, and the second pulse generation unit calculates the corresponding second ripple pulse based on the corrected current ripple data. It is preferable to generate.

According to this configuration, the estimated current ripple is calculated based on each of the current ripple data corrected based on the estimated actual load of the second DC motor. Then, the first ripple pulse is generated based on the estimated current ripple to absorb the fluctuation of the rotation state of the second DC motor according to the actual load, and the rotation state of the first DC motor. Can be detected. On the other hand, the second ripple pulse is generated based on the current ripple data corrected based on the estimated actual load of the second DC motor, so that the second DC motor corresponds to the actual load. It is possible to detect the rotational state of the second DC motor by absorbing the fluctuation of the rotational state of the second DC motor.

The present invention has an effect that even if a plurality of DC motors are driven at the same time, the rotational state of the plurality of DC motors can be individually detected.

The circuit diagram which shows the electric structure of the memory sheet of the vehicle to which one Embodiment of the ripple detection device of a DC motor is applied. (A) and (b) are time charts showing the current ripple of the first DC motor and the current ripple of the second DC motor in a simplified manner. The circuit diagram which shows the electric structure of the ripple detection device of the DC motor of the same embodiment. (A) and (b) are circuit diagrams showing the operation of the memory sheet of the vehicle to which the ripple detection device of the DC motor of the same embodiment is applied. A time chart showing the operation of the ripple detection device of the DC motor of the same embodiment in a simplified manner. The flowchart which shows the control mode of the ripple detection device of the DC motor of the same embodiment.

Hereinafter, a vehicle memory sheet to which one embodiment of the ripple detection device of the DC motor is applied will be described. In addition, this memory seat uses a plurality of DC motors to perform a plurality of adjustment mechanisms (for example, a slide mechanism, a reclining mechanism, a vertical front mechanism, a lift mechanism, etc.) related to the adjustment of a plurality of seat states of a vehicle seat (not shown). Each of them is driven to match the state of the plurality of seats according to the body shape of the seated person and is stored in the memory. Then, even if another seated person sits down and the seat state of the seat is changed, each adjustment mechanism is driven by a DC motor by a simple switch operation thereafter, and the stored initial seat state is easily reproduced. It is a thing.

As shown in FIG. 1, the memory sheet is powered by the battery 10, and the first DC motor 21 and the second DC motor 21 and the second DC motor 21 and the second DC motor 21 (not shown) for driving the first adjustment mechanism (not shown) related to the adjustment of the first seat state. A second DC motor 22 for driving a second adjustment mechanism (not shown) for adjusting the seat state is provided. These first and second DC motors 21 and 22 are so-called DC brush motors that supply a current (motor current) to a rotating armature while switching the energization direction between the brush and the commutator, and are currents per rotation. The number of ripples, which is the number of ripples, is set to be different from each other. Note that FIGS. 2 (a) and 2 (b) show an example of the current ripple included in the motor currents of the first and second DC motors 21 and 22, respectively, simplified into a sine wave for convenience. As shown in the figure, the current ripple contained in the motor current of the second DC motor 22 has a longer period (that is, a lower frequency) and a larger amplitude than the current ripple contained in the motor current of the first DC motor 21. It is changing at.

Further, the memory sheet has a first forward operation switch 23 and a first reverse operation switch 24 related to operations in one direction and the other direction of the first sheet state, and one direction and the other direction of the second sheet state, respectively. It includes a second normal operation switch 25 and a second reverse operation switch 26, a memory reproduction switch 27, a storage switch 28, and a controller 30, respectively, which are related to the operation.

The first forward operation switch 23 and the first reverse operation switch 24 are switches for outputting an operation signal indicating an intention to change the first seat state in one direction and the other direction by the operation of the seated person. The second forward operation switch 25 and the second reverse operation switch 26 are switches for outputting an operation signal indicating an intention to change the second seat state in one direction and the other direction by the operation of the seated person. The memory reproduction switch 27 is a switch for outputting an operation signal indicating an intention to reproduce the seat state (rotational positions of the first and second DC motors 21 and 22) stored in advance in the controller 30 by the operation of the seated person. Is. The storage switch 28 is a switch for outputting an operation signal indicating an intention to be stored in the controller 30 by being operated by a seated person in a predetermined seat state (rotational positions of the first and second DC motors 21 and 22). Is.

The controller 30 includes a microcomputer 31, a pair of first relay switches 32 and 33, a pair of second relay switches 34 and 35, a shunt resistor 36 as a current detection unit, an analog low-pass filter 37, and a ripple detection circuit 40. It is composed of.

The microcomputer 31 includes a ROM that stores various programs and maps, a readable and writable RAM for various data, and an EEPROM that can hold data without a backup power supply (not shown). The sheet state is stored in the EEPROM.

Switches 23 to 28 are connected to the microcomputer 31. The microcomputer 31 detects the corresponding intention based on the operation signals from each of the switches 23 to 28.
Further, relay switches 32 to 35 are connected to the microcomputer 31. Both first relay switches 32 and 33 are connected to both terminals of the first DC motor 21, respectively. In the non-drive state, each of the first relay switches 32 and 33 is connected to the ground GND via the shunt resistor 36 at the corresponding terminal of the first DC motor 21, and a drive signal is output from the microcomputer 31. Then, the corresponding terminal of the first DC motor 21 is connected to the positive electrode terminal + B of the battery 10. As a result, the first DC motor 21 rotates forward or reverse depending on the connection state of the first relay switches 32 and 33, and changes the first seat state in one direction or the other direction. Similarly, both the second relay switches 34 and 35 are connected to both terminals of the second DC motor 22, respectively. In the non-drive state, each of the second relay switches 34 and 35 connects the corresponding terminal of the second DC motor 22 to the ground GND via the shunt resistor 36, and the drive signal is output from the microcomputer 31. Then, the corresponding terminal of the second DC motor 22 is connected to the positive terminal terminal + B of the battery 10. As a result, the second DC motor 22 rotates forward or reverse depending on the connection state of the second relay switches 34 and 35, and changes the second seat state in one direction or the other direction. The first and second DC motors 21 and 22 are connected in series to the shunt resistor 36 in a parallel connection state when both are energized via relay switches 32 to 35.

In other words, a combined motor current that combines the motor currents of both the first and second DC motors 21 and 22 flows through the shunt resistor 36.
Further, a ripple detection circuit 40 is connected to the microcomputer 31. The ripple detection circuit 40 is connected to the shunt resistor 36 via a low-pass filter 37. The low-pass filter 37 outputs a detection signal in which high-frequency components (noise and the like) are cut from a voltage corresponding to the current flowing through the shunt resistor 36 to the ripple detection circuit 40. The ripple detection circuit 40 acquires the current ripple (combined current ripple Iw) included in the current flowing through the shunt resistor 36 based on the detection signal. The ripple detection circuit 40 generates a first ripple pulse RP1 and a second ripple pulse RP2 based on this current ripple and outputs them to the microcomputer 31. The microcomputer 31 individually detects the rotational state of the first and second DC motors 21 and 22 based on the first and second ripple pulses RP1 and RP2. For example, the microcomputer 31 counts the first and second ripple pulses RP1 and RP2 by the edge inputs of the first and second ripple pulses RP1 and RP2, and detects the rotation positions of the first and second DC motors 21 and 22. .. Alternatively, the microcomputer 31 clocks the time from the edge input of the previous first and second ripple pulses RP1 and RP2 to the edge input of the next first and second ripple pulses RP1 and RP2 to measure the first and second direct currents. The rotation speed of the motors 21 and 22 is detected.

Here, for example, when an operation signal is output from any of the operation switches 23 to 26, the microcomputer 31 rotates (forward or reverse) the corresponding DC motors 21 and 22 in the corresponding direction and ripple pulses RP1 and RP2. The rotation position of the DC motors 21 and 22 is detected based on the above. Then, when the output of the operation signal from the operation switches 23 to 26 is stopped, the microcomputer 31 stops driving the corresponding DC motors 21 and 22, and at the same time, sets the rotation position of the DC motors 21 and 22 at that time. Store in EEPROM. Further, at this time, when the operation signal is output from the storage switch 28, the microcomputer 31 stores the rotation position of the DC motors 21 and 22 at that time in the EEPROM as the reproduction memory position. After that, when the operation signal is output from the memory reproduction switch 27, the microcomputer 31 starts driving the DC motors 21 and 22 in order to return the rotation position of the DC motors 21 and 22 to the reproduction memory position. With the return to the reproduction memory position, the drive of the DC motors 21 and 22 is stopped.

Next, the electrical configuration of the ripple detection circuit 40 will be described.
As shown in FIG. 3, the ripple detection circuit 40 includes an A / D conversion unit 41, a first acquisition unit 42a incorporating a logic circuit, a calculation unit 42b, a first pulse generation unit 42c, and a second pulse generation unit 42d. It includes a second acquisition unit 42e, an estimation unit 42f, a ripple detection logic unit 42 as a correction unit 42g, and a non-volatile memory 43 as a rewritable storage unit including, for example, an EEPROM. The A / D conversion unit 41 is connected to the low-pass filter 37 and also to the ripple detection logic unit 42. The ripple detection logic unit 42 is connected to the microcomputer 31. Further, the ripple detection logic unit 42 is connected to the memory 43, and writes / reads various information (data) to the memory 43.

The ripple detection logic unit 42 is configured to receive drive information (for example, information such as rotation start / stop, rotation direction, etc.) of the DC motors 21 and 22 from the microcomputer 31. Further, the memory 43 updates and stores the current rotation positions and rotation speeds of the first and second DC motors 21 and 22. Alternatively, the memory 43 stores in advance a map in which the relationship between the rotation position of the second DC motor 22 and the current ripple (numerical value) is experimentally obtained for each rotation direction. Specifically, in the memory 43, for example, the current ripple corresponding to the rotation position and the rotation direction of the second DC motor 22 is stored in advance as the current ripple data DI. This is because the current ripple basically fluctuates according to the load (torque) uniquely determined according to the rotation position and rotation direction (second seat state and its change direction) of the second DC motor 22. be.

Alternatively, the memory 43 stores in advance a map in which the relationship between the amplitude of the current ripple and the actual load of the second DC motor 22 (for example, the weight of the seated seat) is experimentally obtained. This is because the amplitude of the current ripple fluctuates according to the actual load of the second DC motor 22. In other words, the actual load of the second DC motor 22 can be estimated by monitoring the difference between the amplitude of the original current ripple corresponding to the rotation position and the rotation direction of the second DC motor 22 and the measured amplitude. ..

Next, a mode in which the first and second ripple pulses RP1 and RP2 are generated by the ripple detection logic unit 42 will be described. In the following, the current ripples of the first and second DC motors 21 and 22 will be described as sine waves according to FIG.

First, as shown in FIG. 4A, it is assumed that only the second DC motor 22 is energized via the second relay switches 34 and 35. At this time, the motor current of only the second DC motor 22 (that is, the combined motor current in which the motor current of the first DC motor 21 is zero) flows through the shunt resistor 36, and as shown in FIG. 5, the current ripple of the second DC motor 22 Changes. The ripple detection logic unit 42 acquires this current ripple as a single current ripple Is (second acquisition unit 42e), and based on the singular points (for example, maximum point, minimum point, zero cross point, etc.) of the single current ripple Is, the first 2 Ripple pulse RP2 is generated (second pulse generation unit 42d) and output to the microcomputer 31. Further, the ripple detection logic unit 42 counts the second ripple pulse RP2, detects the rotation position of the second DC motor 22, and updates / stores the second ripple pulse RP2 in the memory 43.

The single current ripple Is changes according to the current ripple (current ripple data DI) of the second DC motor 22 obtained experimentally in advance. However, since the rotation speed of the second DC motor 22 fluctuates according to an actual load (for example, the weight of the seated person), the single current ripple Is also fluctuates according to the load. For example, as the load increases, the rotation speed of the second DC motor 22 decreases, so that the frequency of the single current ripple Is also decreases. On the contrary, as the load decreases, the rotation speed of the second DC motor 22 increases, so that the frequency of the single current ripple Is also increases. Further, as the load increases, the amplitude of the solitary current ripple Is increases, and conversely, as the load decreases, the amplitude of the solitary current ripple Is decreases. The ripple detection logic unit 42 monitors the difference between the amplitude of the original current ripple corresponding to the rotation position and the rotation direction of the second DC motor 22 and the amplitude of the single current ripple Is (measured amplitude), so that the second DC The actual load of the motor 22 is estimated (estimating unit 42f).

Then, the ripple detection logic unit 42 corrects the current ripple data DI so as to change according to the actual load of the second DC motor 22 estimated at this time (correction unit 42g). Specifically, the current ripple data DIc is calculated by correcting the frequency and amplitude of the current ripple data DI according to the estimated actual load of the second DC motor 22.

Next, as shown in FIG. 4B, it is assumed that the first and second DC motors 21 and 22 are simultaneously energized via the relay switches 32 to 35. At this time, the motor currents (combined motor currents) of both the first and second DC motors 21 and 22 flow through the shunt resistor 36, and as shown in FIG. 5, the current included in the combined motor current obtained by synthesizing all the motor currents. Ripple changes. The ripple detection logic unit 42 acquires this current ripple as the combined current ripple Iw (first acquisition unit 42a), and subtracts the current ripple data DIc corrected in the above-described embodiment from the combined current ripple Iw to estimate the current. Ripple Ig is calculated (calculation unit 42b).

The ripple detection logic unit 42 generates a first ripple pulse RP1 (first pulse generation unit 42c) based on a singular point (for example, a maximum point, a minimum point, a zero cross point, etc.) of the estimated current ripple Ig, and outputs the first ripple pulse RP1 to the microcomputer 31. do. Further, the ripple detection logic unit 42 counts the first ripple pulse RP1 to detect the rotation position of the first DC motor 21, and updates and stores the first ripple pulse RP1 in the memory 43. Similarly, the ripple detection logic unit 42 generates the second ripple pulse RP2 based on the singular points (for example, maximum point, minimum point, zero cross point, etc.) of the corrected current ripple data DIc (second pulse generation unit 42d). ), Output to the microcomputer 31. Further, the ripple detection logic unit 42 counts the second ripple pulse RP2, detects the rotation position of the second DC motor 22, and updates / stores the second ripple pulse RP2 in the memory 43.

If one of the DC motors 21 and 22 is stopped and the other drive is continued (the case of the second DC motor 22 is shown in FIG. 5), the single current ripple Is described above is applied. The corresponding ripple pulses RP1 and RP2 may be generated.

Next, the generation modes of the first and second ripple pulses RP1 and RP2 executed by the ripple detection logic unit 42 will be summarized and described based on the flowchart. This routine is activated when, for example, the microcomputer 31 starts driving the second DC motor 22 with the output of the operation signal from the memory reproduction switch 27.

As shown in FIG. 6, when the process shifts to this routine, the ripple detection logic unit 42 acquires the single current ripple Is (step S1). Then, the ripple detection logic unit 42 generates and outputs the second ripple pulse RP2 based on the single current ripple Is (step S2). Subsequently, the ripple detection logic unit 42 determines whether or not the detection of the amplitude of the single current ripple Is has been completed (step S3), and if it is determined that the detection of the amplitude of the single current ripple Is has not been completed. The process returns to step S1 and the same process is repeated. On the other hand, when it is determined that the detection of the amplitude of the single current ripple Is is completed, the current ripple data DI is corrected based on the amplitude (step S4).

Subsequently, the ripple detection logic unit 42 determines whether or not the driving of the first DC motor 21 has been started (step S5), and if it is determined that the driving of the first DC motor 21 has not been started, step S1 Return to and repeat the same process. On the other hand, when it is determined that the driving of the first DC motor 21 has started, the ripple detection logic unit 42 acquires the combined current ripple Iw (step S6).

The ripple detection logic unit 42 subtracts the corrected current ripple data DIc from the combined current ripple Iw to calculate the estimated current ripple Ig (step S7). Then, the ripple detection logic unit 42 generates the first ripple pulse RP1 based on the estimated current ripple Ig, and generates the second ripple pulse RP2 based on the corrected current ripple data DIc (step S8). Then, the ripple detection logic unit 42 outputs the first and second ripple pulses RP1 and RP2 (step S9).

Subsequently, the ripple detection logic unit 42 determines whether or not the drive of any of the first and second DC motors 21 and 22 is stopped (step S10), and the first and second DC motors 21 and 22 If it is determined that both drives are not stopped, the process returns to step S7 and the same process is repeated. On the other hand, when it is determined that the drive of any of the first and second DC motors 21 and 22 is stopped, the ripple detection logic unit 42 applies the corresponding ripple pulses RP1 and RP2 according to the above-mentioned single current ripple Is. Generate and output (see steps S1 and S2). Then, when it is determined that both the driving of the first and second DC motors 21 and 22 has been stopped, the ripple detection logic unit 42 ends the processing (these processing are not shown).

The ripple detection logic unit 42 detects the rotation positions of the first and second DC motors 21 and 22 by themselves in accordance with the generation of the first and second ripple pulses RP1 and RP2 described above. Further, as described above, the ripple detection logic unit 42 receives the information on the rotation directions of the first and second DC motors 21 and 22 from the microcomputer 31. The ripple detection logic unit 42 sets the current ripple data DI and its correction value (correction value based on the amplitude of the single current ripple Is) according to the rotation position and rotation direction of the first and second DC motors 21 and 22 at that time. Needless to say, it is read from the corresponding map.

Next, the operation of the present embodiment and its effect will be described.
(1) In the present embodiment, the first ripple pulse RP1 is generated based on the estimated current ripple Ig in a state where the first and second DC motors 21 and 22 are driven at the same time. On the other hand, the second ripple pulse RP2 is generated based on the current ripple data DI. Therefore, even if the first and second DC motors 21 and 22 are driven at the same time, the rotational states of the first and second DC motors 21 and 22 can be detected individually. Then, the microcomputer 31 drives and controls the first and second DC motors 21 and 22 based on the rotation states of the first and second DC motors 21 and 22, that is, the rotation of the first and second DC motors 21 and 22. It is possible to control the return to the corresponding playback memory position of the position.

(2) In the present embodiment, the estimated current ripple Ig is calculated based on the current ripple data DIc corrected based on the estimated actual load of the second DC motor. Then, the first ripple pulse RP1 is generated based on the estimated current ripple Ig to absorb the fluctuation of the rotation state of the second DC motor 22 according to the actual load and rotate the first DC motor 21. The state can be detected. On the other hand, the second ripple pulse RP2 is generated based on the current ripple data DIc corrected based on the estimated actual load of the second DC motor, so that the second DC motor 22 rotates according to the actual load. The rotational state of the second DC motor 22 can be detected by absorbing the fluctuation of the state.

(3) In the present embodiment, even if the first and second DC motors 21 and 22 are driven at the same time, the rotational states of the first and second DC motors 21 and 22 are individually detected by one ripple detection circuit 40. Therefore, the circuit configuration can be simplified and the cost can be reduced.

(4) In the present embodiment, even if the first and second DC motors 21 and 22 are driven at the same time, the rotational states of the first and second DC motors 21 and 22 can be detected individually. Therefore, for example, the first and second DC motors 21 and 22 can be detected individually. Compared with the case where the second DC motors 21 and 22 are sequentially driven, the rotational positions of the first and second DC motors 21 and 22 can be quickly returned to the corresponding reproduction memory positions. As a result, the operability of adjusting the first and second seat states by the seated person can be improved.

The above embodiment may be changed as follows.
-In the above embodiment, the number of ripples per rotation of the first and second DC motors 21 and 22 is set so that the number of slots and the least common multiple of the number of segments of the commutator (the number of commutator pieces) are different from each other. Just do it.

-In the above embodiment, the memory 43 may be built in the ripple detection logic unit 42.
-In the above embodiment, the ripple detection logic unit 42 may receive from the microcomputer 31 without detecting the rotation position and the rotation speed of the first and second DC motors 21 and 22 by themselves.

-In the above embodiment, in estimating the actual load of the second DC motor, the wave height may be adopted instead of the amplitude of the single current ripple Is.
-In the above-described embodiment, in the correction of the current ripple data DI based on the amplitude of the single current ripple Is, the correction value (map) is stored in the memory 43, and the correction value (map) is stored in the memory 43 according to the estimated actual load of the second DC motor. It was performed based on the correction value read in. On the other hand, a plurality of types of current ripple data DIs according to the estimated actual load of the second DC motor 22 are stored in the memory 43, and the corresponding items correspond to the estimated load of the second DC motor 22. It may be performed based on the selection of the current ripple data DI of the type to be used.

-In the above embodiment, the correction of the current ripple data DI based on the estimated actual load of the second DC motor 22 may be omitted. In this case, the acquisition of the independent current ripple Is, that is, the independent drive of the second DC motor 22 immediately before the simultaneous drive of the first and second DC motors 21 and 22 may be omitted.

In the above embodiment, if the second DC motor 22 has a sufficient rated output in which the motor current does not fluctuate depending on the rotation position, the current ripple data DI for the predetermined rotation (for example, one rotation) is stored in the memory 43. You may leave it.

-In the above-described embodiment, if the motor current does not fluctuate depending on the rotation direction, the current ripple data DI shared in both rotation directions may be stored in the memory 43.
-In the above embodiment, three or more types of seat states may be adjusted by three or more DC motors. In this case, the current ripple data corresponds to all the rotation positions and rotation directions of the DC motor (second DC motor) other than the DC motor (first DC motor) of one of these three or more DC motors. It may be stored individually in the memory 43 as DI. Then, in a state where three or more DC motors are driven at the same time, the estimated current ripple Ig may be calculated by subtracting all the current ripple data DIs at the corresponding rotation positions and rotation directions from the combined current ripple. Further, in the calculation of the estimated current ripple Ig, the current ripple data DIc individually corrected based on the estimated actual load of the second DC motor may be adopted.

-In the above embodiment, the ripple detection logic unit 42 and the memory 43 may be omitted and their functions may be mounted on the microcomputer 31. In this case, it is not necessary to send and receive drive information (for example, information such as rotation start / stop and rotation direction) of the DC motors 21 and 22 between the microcomputer 31 and the ripple detection circuit 40.

Further, the A / D conversion unit 41 may be further omitted and the function may be mounted on the microcomputer 31. That is, the entire ripple detection circuit 40 may be omitted.
Next, the technical idea that can be grasped from the above embodiment and another example will be added below.

(B) In the ripple detection device of the above DC motor
The storage unit stores a correction value according to the estimated load of the second DC motor.
The correction unit is a DC motor ripple detection device that corrects each current ripple data based on the correction value read according to the estimated load of the second DC motor.

(B) In the ripple detection device of the above DC motor
The storage unit stores a plurality of types of each current ripple data according to the estimated load of the second DC motor.
The correction unit is a DC motor ripple detection device that corrects each current ripple data based on the selection of the corresponding current ripple data of the corresponding type according to the estimated load of the second DC motor.

(C) A current detector that detects a combined motor current that is connected in series to two parallel-connected DC motors with different ripple numbers per rotation and that combines all of the motor currents of both DC motors.
A first acquisition unit that acquires the current ripple included in the combined motor current in a state where both DC motors are driven at the same time as a combined current ripple.
A storage unit that stores the current ripple corresponding to the rotation position and rotation direction of the second DC motor, which is the DC motor other than the first DC motor, which is one of the two DC motors, as current ripple data.
In a state where both DC motors are driven at the same time, the estimated current ripple included in the motor current of the first DC motor is obtained by subtracting the current ripple data in the corresponding rotation position and rotation direction from the acquired combined current ripple. And the arithmetic unit that calculates
A first pulse generator that generates a first ripple pulse that represents the rotational state of the first DC motor based on the estimated current ripple.
A DC motor ripple detection device including a second pulse generating unit that generates a second ripple pulse representing a rotational state of the second DC motor based on the current ripple data.

21 ... 1st DC motor, 21 and 22 ... DC motor, 22 ... 2nd DC motor, 36 ... Shunt resistance (current detection unit), 42 ... Ripple detection logic unit, 42a ... 1st acquisition unit, 42b ... Calculation unit, 42c ... 1st pulse generation unit, 42d ... 2nd pulse generation unit, 42e ... 2nd acquisition unit, 42f ... estimation unit, 42g ... correction unit, 43 ... memory (storage unit).

Claims (2)

A current detector that detects a combined motor current that is connected in series to multiple parallel-connected DC motors with different ripple numbers per rotation and that combines all of the motor currents of those multiple DC motors.
A first acquisition unit that acquires the current ripple included in the combined motor current in a state where the plurality of DC motors are driven at the same time as a combined current ripple.
The current ripples corresponding to all the rotation positions and rotation directions of the second DC motor, which is the DC motor other than the first DC motor, which is one of the plurality of DC motors, are individually used as current ripple data. A storage unit to memorize and
In a state where the plurality of DC motors are driven at the same time, all of the current ripple data in the corresponding rotation position and rotation direction are subtracted from the acquired combined current ripple and included in the motor current of the first DC motor. An arithmetic unit that calculates the estimated current ripple,
A first pulse generator that generates a first ripple pulse that represents the rotational state of the first DC motor based on the estimated current ripple.
A DC motor ripple detection device including a second pulse generating unit that generates a second ripple pulse representing a rotational state of the corresponding second DC motor based on each current ripple data. In the ripple detection device for a DC motor according to claim 1.
A second acquisition unit that acquires the current ripple included in the combined motor current in a state where the second DC motor is independently driven as a single current ripple, and a second acquisition unit.
An estimation unit that estimates the actual load of the second DC motor based on the single current ripple, and
A correction unit for individually correcting all current ripple data of the second DC motor based on the estimated load is provided.
The calculation unit calculates the estimated current ripple based on the corrected current ripple data, and then calculates the estimated current ripple.
The second pulse generation unit is a ripple detection device for a DC motor that generates the corresponding second ripple pulse based on the corrected current ripple data.

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