JP7699620B2 - Motor control device and vehicle - Google Patents

Description

The present invention relates to a motor control device and a vehicle.

In recent years, efforts to realize a low-carbon or carbon-free society have been intensified, and research and development of electrification technologies has been conducted in order to reduce _CO2 emissions and improve energy efficiency in vehicles. One of the electrification technologies is a technology in which a drive voltage having a predetermined voltage waveform is applied to drive a motor provided in a vehicle.

Patent document 1 discloses a technology that performs square wave energization drive when the rotation speed of the DC motor is below a threshold value, and performs sine wave energization drive when the rotation speed of the DC motor is equal to or greater than the threshold value. The technology disclosed in patent document 1 makes it possible to avoid braking operation at the time of phase switching when starting the motor, and to suppress reduction in starting torque.

Patent Document 2 discloses a technique for calculating the rotation speed of a permanent magnet rotor provided in a brushless motor based on the time interval of a half cycle or one cycle, which is the interval between the rising or falling edges of a pulsed position sensor signal detected by each Hall sensor provided in the brushless motor. The technique disclosed in Patent Document 2 can reduce calculation errors in the rotation speed caused by variations in the mounting position of each Hall sensor, realizing a brushless motor that rotates smoothly and produces little noise.

JP 2004-242432 A JP 2003-264990 A

However, one of the technologies related to electrification is motor drive technology , which has the problem that the motor output is unstable at low revolutions.

The present invention aims to solve the above problems , particularly to achieve stabilization of motor output when re-accelerating at low rotation speeds after rapid deceleration , and ultimately to contribute to improving energy efficiency.

One aspect for achieving the above object includes a drive unit capable of selectively driving the motor by rectangular wave voltage drive, which applies a rectangular wave voltage to a stator winding provided in the motor to drive the motor, and vector control drive, which applies a sine wave voltage to the stator winding to drive the motor, a command unit that outputs a torque command value that indicates a torque of the motor, and a switching unit that causes the drive unit to switch the drive of the motor to the rectangular wave voltage drive or the vector control drive, and the switching unit is configured to, when the motor is controlled by the vector control drive, switch the torque command value (τ ^* ) changes to a value indicating an increase in torque, the motor control device switches the drive of the motor from the vector control drive to the rectangular wave voltage drive , drives the motor by low-speed drive, which is the rectangular wave voltage drive switched based on the change in the torque command value, and then terminates the drive of the motor by the low-speed drive on condition that a signal level of a position signal indicating a rotational position of a rotor provided in the motor has changed, and switches the drive of the motor to the rectangular wave voltage drive or the vector control drive depending on the rotational speed (ω) at the time the low-speed drive is terminated .
Another aspect for achieving the above-mentioned object is a motor control device comprising a drive unit capable of selectively driving the motor by rectangular wave voltage driving, which applies a rectangular wave voltage to a stator winding provided in the motor to drive the motor, and vector control driving, which applies a sinusoidal wave voltage to the stator winding to drive the motor, a command unit that outputs a torque command value that indicates the torque of the motor, and a switching unit that causes the drive unit to switch the driving of the motor to the rectangular wave voltage driving or the vector control driving, wherein when the motor is controlled by the vector control driving, if the rotational speed (ω) of the motor becomes equal to or lower than a threshold value and the torque command value (τ ^* ) input from the command unit changes to a value that indicates a torque increase, the switching unit switches the driving of the motor from the vector control driving to the rectangular wave voltage driving, and if the torque increase amount indicated in the change in the torque command value is equal to or greater than a predetermined value, the switching unit switches the driving of the motor from the vector control driving to the rectangular wave voltage driving.

Furthermore, still another aspect for achieving the above object is a vehicle comprising a motor control device of the above one aspect or the other aspect , the motor, and a position detection unit that outputs a position signal indicating the rotational position of a rotor provided in the motor.

The above aspect makes it possible to achieve stabilization of motor output at low speeds.

1 is a block diagram showing an example of a schematic configuration of a motor control device and a vehicle according to an embodiment of the present disclosure. 1 is a diagram illustrating an example of a circuit configuration of an inverter unit provided in a motor control device according to an embodiment of the present disclosure. 4 is a flowchart illustrating an example of an operation flow of a motor control device according to an embodiment of the present disclosure. 4 is a timing chart showing an example of operation timing of a motor control device according to an embodiment of the present disclosure. 5A to 5C are diagrams illustrating an example of voltage waveforms and signal waveforms of Hall detection signals during vector control driving in a motor control device according to an embodiment of the present disclosure. 5A and 5B are diagrams illustrating rotor position detection in a motor control device according to an embodiment of the present disclosure. 5A to 5C are diagrams illustrating an example of a voltage waveform and a signal waveform of a Hall detection signal when driven by a square wave voltage in a motor control device according to an embodiment of the present disclosure.

[1. Configuration of the motor control device and vehicle]
1 is a block diagram showing an example of a schematic configuration of a motor control device 10 and a vehicle 1 according to an embodiment of the present disclosure. The vehicle 1 includes the motor control device 10, a motor 20 controlled by the motor control device 10, and a plurality of hall sensors (examples of position detection units) 22u, 22v, and 22w that output hall detection signals (examples of position signals) Hu, Hv, and Hw that indicate the rotational position of a rotor 23 provided in the motor 20. Examples of the vehicle 1 include an automobile and a motor-driven bicycle.

The motor 20 is, for example, a brushless motor. The motor 20 includes a rotor 23 provided with a permanent magnet (not shown) and a stator (not shown) provided with a U-phase winding 21u, a V-phase winding 21v, and a W-phase winding 21w (each of which is an example of a stator winding). The U-phase winding 21u, the V-phase winding 21v, and the W-phase winding 21w are arranged at 120° intervals. The hall sensors 22u, 22v, and 22w are arranged at 120° intervals and shifted 60° from the U-phase winding 21u, the V-phase winding 21v, and the W-phase winding 21w. In this embodiment, the hall sensor 22u is arranged between the U-phase winding 21u and the W-phase winding 21w, the hall sensor 22v is arranged between the U-phase winding 21u and the V-phase winding 21v, and the hall sensor 22w is arranged between the V-phase winding 21v and the W-phase winding 21w.

Next, the configuration of the motor control device 10 will be described with reference to FIGS.
1, the motor control device 10 includes a drive unit 11 connected to a U-phase winding 21u, a V-phase winding 21v, and a W-phase winding 21w provided on a motor 20. The motor control device 10 includes a detection unit 12 connected to Hall sensors 22u, 22v, and 22w provided on the motor 20, and a rotation speed calculation unit 13 connected to the Hall sensor 22u. The motor control device 10 includes a switching unit 14 connected to the drive unit 11 and the rotation speed calculation unit 13, and a command unit 15 connected to the drive unit 11, the detection unit 12, the rotation speed calculation unit 13, and the switching unit 14.

The drive unit 11 is configured to selectively drive the motor 20 by a rectangular wave voltage drive that applies a rectangular wave voltage to the U-phase winding 21u, the V-phase winding 21v, and the W-phase winding 21w provided in the motor 20 to drive the motor 20, and a vector control drive that applies a sine wave voltage to the U-phase winding 21u, the V-phase winding 21v, and the W-phase winding 21w to drive the motor 20. The drive unit 11 has a rectangular wave voltage drive unit 111, a vector control drive unit 112, and an inverter unit 113. The rectangular wave voltage drive unit 111 is switched between a state in which the output is electrically connected to the inverter unit 113 and a state in which the output is electrically disconnected from the inverter unit 113 by a drive switching signal Scd1 input from the switching unit 14. The vector control drive unit 112 is switched between a state in which the output is electrically connected to the inverter unit 113 and a state in which the output is electrically disconnected from the inverter unit 113 by the drive switching signal Scd2 input from the switching unit 14. The rectangular wave voltage drive unit 111 and the vector control drive unit 112 are electrically disconnected from the input of the inverter unit 113 by putting the output into, for example, a high impedance state.

When the drive unit 11 is switched to operate with the rectangular wave voltage drive unit 111 by the switching unit 14, the drive unit 11 drives the motor 20 with rectangular wave voltage drive by the rectangular wave voltage drive unit 111 and the inverter unit 113. On the other hand, when the drive unit 11 is switched to operate with the vector control drive unit 112 by the switching unit 14, the drive unit 11 drives the motor 20 with vector control drive by the vector control drive unit 112 and the inverter unit 113.

The rectangular wave voltage driver 111 generates pulse signals Pau, Pav, Paw, Pax, Pay, and Paz for driving the inverter unit 113, using the q-axis current command value Iq ^* input from the command unit 15, the U-phase current Iu, the V-phase current Iv, and the W-phase current Iw input from the inverter unit 113, and the rotation angle signal Sθ of the motor 20 input from the detection unit 12. Hereinafter, the "pulse signals Pau, Pav, Paw, Pax, Pay, and Paz" may be abbreviated as "pulse signals Pau to Paz".

The vector control drive unit 112 generates pulse signals Pbu, Pbv, Pbw, Pbx, Pby, and Pbz for driving the inverter unit 113, using the d-axis current command value Id ^* and the q-axis current command value Iq ^* input from the command unit 15, the U-phase current Iu, the V-phase current Iv, and the W-phase current Iw input from the inverter unit 113, and the rotation angle signal Sθ input from the detection unit 12. Hereinafter, the "pulse signals Pbu, Pbv, Pbw, Pbx, Pby, and Pbz" may be abbreviated as "pulse signals Pbu to Pbz".

When the switching unit 14 switches the drive of the motor 20 to rectangular wave voltage drive, the drive unit 11 inputs the pulse signals Pau, Pav, Paw, Pax, Pay, Paz to the inverter unit 113 as pulse signals Pu, Pv, Pw, Px, Py, Pz. When the switching unit 14 switches the drive of the motor 20 to vector control drive, the drive unit 11 inputs the pulse signals Pbu, Pbv, Pbw, Pbx, Pby, Pbz to the inverter unit 113 as pulse signals Pu, Pv, Pw, Px, Py, Pz. Hereinafter, "pulse signals Pu, Pv, Pw, Px, Py, Pz" may be abbreviated as "pulse signals Pu to Pz".

FIG. 2 shows an example of a circuit configuration of the inverter unit 113.
As shown in FIG. 2, the inverter unit 113 is configured by connecting six semiconductor elements Qu, Qv, Qw, Qx, Qy, and Qz in a full bridge configuration between a positive line Lp to which a positive DC voltage is applied and a negative line Ln to which a negative DC voltage is applied. Hereinafter, the "semiconductor elements Qu, Qv, Qw, Qx, Qy, and Qz" may be abbreviated as "semiconductor elements Qu to Qz." The semiconductor elements Qu and Qx are connected in series between the positive line Lp and the negative line Ln to form a U-phase arm 113u. The semiconductor elements Qv and Qy are connected in series between the positive line Lp and the negative line Ln to form a V-phase arm 113v. The semiconductor elements Qw and Qz are connected in series between the positive line Lp and the negative line Ln to form a W-phase arm 113w. Each of the semiconductor elements Qu to Qz includes a power semiconductor element and a free wheel diode connected in anti-parallel to the power semiconductor element.

A pulse signal Pu is input to the gate of the power semiconductor element provided in the semiconductor element Qu, and a pulse signal Px is input to the gate of the power semiconductor element provided in the semiconductor element Qx. A pulse signal Pv is input to the gate of the power semiconductor element provided in the semiconductor element Qv, and a pulse signal Py is input to the gate of the power semiconductor element provided in the semiconductor element Qy. A pulse signal Pw is input to the gate of the power semiconductor element provided in the semiconductor element Qw, and a pulse signal Pz is input to the gate of the power semiconductor element provided in the semiconductor element Qz. The semiconductor elements Qu to Qz are controlled to be turned on and off at a predetermined timing and in a predetermined order by the pulse signals Pu to Pz. As a result, the U-phase arm 113u outputs a U-phase AC voltage Vu from the connection part of the semiconductor elements Qu and Qx to the U-phase winding 21u provided in the motor 20 (see FIG. 1). The V-phase arm 113v outputs a V-phase AC voltage Vv from the connection between the semiconductor elements Qv and Qy to the V-phase winding 21v provided in the motor 20. The W-phase arm 113w outputs a W-phase AC voltage Vw from the connection between the semiconductor elements Qw and Qz to the W-phase winding 21w provided in the motor 20.

When the inverter unit 113 operates, an AC U-phase current Iu flowing between the inverter unit 113 and the motor 20 is output from the U-phase arm 113u to the drive unit 11, an AC V-phase current Iv flowing between the inverter unit 113 and the motor 20 is output from the V-phase arm 113v to the drive unit 11, and an AC W-phase current Iw flowing between the inverter unit 113 and the motor 20 is output from the W-phase arm 113w to the drive unit 11.

Returning to FIG. 1, the command unit 15 outputs a torque command value τ ^* that indicates the torque of the motor 20. The command unit 15 generates the torque command value τ ^* based on the rotation speed of the motor 20 calculated by the rotation speed calculation unit 13, the rotation speed command value input from the outside, and the accelerator opening input from the outside. The command unit 15 also generates a d-axis current command value Id ^* and a q-axis current command value Iq ^* based on the generated torque command value τ ^* and the rotation angle of the rotor 23 input from the detection unit 12. The command unit 15 outputs the generated torque command value τ ^* to the switching unit 14. The command unit 15 outputs the generated q-axis current command value Iq ^* to the rectangular wave voltage drive unit 111. The command unit 15 outputs the generated d-axis current command value Id ^* and q-axis current command value Iq ^* to the vector control drive unit 112.

The detection unit 12 detects the rotational position (i.e., rotation angle) of the rotor 23 provided in the motor 20. The detection unit 12 receives a Hall detection signal Hu output from a Hall sensor 22u provided in the motor 20, a Hall detection signal Hv output from a Hall sensor 22v provided in the motor 20, and a Hall detection signal Hw output from a Hall sensor 22w provided in the motor 20. Although details will be described later, the detection unit 12 determines the angle (electrical angle) of the rotating magnetic field in the motor 20 based on a combination of voltage levels of the Hall detection signals Hu, Hv, and Hw input from the motor 20, and detects the rotation angle of the rotor 23 based on the determined electrical angle. If the electrical angle of the motor 20 is θe and the number of magnetic poles of the permanent magnet provided in the rotor 23 is p, the detection unit 12 detects the rotation angle θ of the rotor 23 by the following formula (1).
θ=θe×2/p...(1)

The detection unit 12 detects the rotation angle θ of the rotor 23 based on equation (1) and outputs a rotation angle signal Sθ including information on the rotation angle θ to the drive unit 11 and the command unit 15.

The switching unit 14 causes the drive unit 11 to switch the drive of the motor 20 to square wave voltage drive or vector control drive. Although details will be described later, the switching unit 14 switches the drive of the motor 20 from vector control drive to square wave voltage drive when the torque command value τ ^* input from the command unit 15 changes in a state in which the motor 20 is driven at a rotation speed equal to or lower than a threshold value by vector control drive. The switching unit 14 causes the drive unit 11 to switch the drive of the motor 20 based on the drive and rotation speed of the motor 20, so that the motor control device 10 can stabilize the output of the motor 20 at low rotation speeds.

When the switching unit 14 outputs the drive switching signal Scd1 to the rectangular wave voltage driving unit 111, it determines that the motor 20 is driven by the rectangular wave voltage drive, and when the switching unit 14 outputs the drive switching signal Scd2 to the vector control driving unit 112, it determines that the motor 20 is driven by the vector control drive. The switching unit 14 obtains the rotation speed ω of the motor 20 from the rotation speed signal Sω input from the rotation speed calculation unit 13.

The switching unit 14 receives a Hall detection signal Hu output from a Hall sensor 22u provided on the motor 20. Details will be described later, but when the switching unit 14 instructs the drive unit 11 to switch the drive of the motor 20 to square wave voltage drive in order to stabilize the output of the motor 20 at low speed, the switching unit 14 determines whether or not to end the square wave voltage drive based on a change in the signal level of the Hall detection signal Hu.

When the motor 20 is driven by the rectangular wave voltage drive, the switching unit 14 electrically connects the output of the rectangular wave voltage drive unit 111 to the inverter unit 113 and electrically disconnects the output of the vector control drive unit 112 from the inverter unit 113. On the other hand, when the motor 20 is driven by the vector control drive, the switching unit 14 electrically disconnects the output of the rectangular wave voltage drive unit 111 from the inverter unit 113 and electrically connects the output of the vector control drive unit 112 to the inverter unit 113. Therefore, even if the drive unit 11 has a configuration in which the output of the rectangular wave voltage drive unit 111 and the output of the vector control drive unit 112 are connected and connected to the input of the inverter unit 113, it is possible to input only one of the pulse signals Pau to Paw and Pbu to Pbw to the inverter unit 113 as the pulse signals Pu to Pw without interference between the pulse signals Pau to Paw and the pulse signals Pbu to Pbw.

The rotation speed calculation unit 13 calculates the rotation speed ω of the motor 20 based on any one of the multiple Hall detection signals Hu, Hv, and Hw. In this embodiment, the rotation speed calculation unit 13 calculates the rotation speed ω of the motor 20 (more specifically, the rotation angular speed of the rotor 23) using, for example, the Hall detection signal Hu. However, the rotation speed calculation unit 13 may calculate the rotation speed ω of the motor 20 using the Hall detection signal Hv or the Hall detection signal Hw. If the number of magnetic poles of the permanent magnet provided in the rotor 23 is p and the frequency of the Hall detection signal Hu is f, the rotation speed calculation unit 13 calculates the rotation speed ω of the motor 20 by the following formula (2). The rotation speed calculation unit 13 outputs a rotation speed signal Sω including information on the calculated rotation speed ω to the switching unit 14 and the command unit 15.
ω=2×π×f/(p/2)
=2×π×2×f/p...(2)

2. Operation of the Motor Control Device
[2-1. Operational flow of the motor control device]
The operation of the motor control device 10 according to this embodiment will be described using Figures 3 to 7 with reference to Figures 1 and 2. Figure 3 is a flowchart showing an example of the flow of operation of the motor control device 10. The process shown in Figure 3 is started, for example, when the motor control device 10 is powered on (i.e., the power is turned on).

As shown in FIG. 3, when the motor control device 10 (see FIG. 1) starts controlling the motor 20 (see FIG. 1), in step S11, the switching unit 14 (see FIG. 1) determines whether the drive of the motor 20 is vector control drive. If the switching unit 14 is outputting the drive switching signal Scd2 to the vector control drive unit 112 (step S11: YES), the switching unit 14 determines that the drive of the motor 20 is vector control drive, and proceeds to the process of step S12. On the other hand, if the switching unit 14 is outputting the drive switching signal Scd1 to the square wave voltage drive unit 111 (step S11: NO), the switching unit 14 determines that the drive of the motor 20 is square wave voltage drive, and proceeds to the process of step S17.

In step S12, the switching unit 14 determines whether the rotation speed ω of the motor 20 included in the rotation speed signal Sω input from the rotation speed calculation unit 13 (see FIG. 1) is equal to or less than the threshold value ωth. If the switching unit 14 determines that the rotation speed ω of the motor 20 is equal to or less than the threshold value ωth (step S12: YES), the processing proceeds to step S13. On the other hand, if the switching unit 14 determines that the rotation speed ω of the motor 20 is greater than the threshold value ωth (step S12: NO), the processing proceeds to step S17. The threshold value ωth is a rotation speed in the extremely low rotation region, and is set to a value higher than the drive switching threshold value ωthc described below. The threshold value ωth is determined by experiments, simulations, etc., and may be set to a different value for each type of vehicle 1 (see FIG. 1).

In step S13, the switching unit 14 judges whether the torque command value τ ^* input from the command unit 15 has changed. For example, the switching unit 14 differentiates the torque command value τ ^* with respect to time, and if the result of the time differentiation is positive, it judges that the torque command value τ ^* has changed to increase (step S13: YES) and proceeds to processing of step S14. On the other hand, if the result is negative or zero, for example, the switching unit 14 judges that the torque command value τ ^* has not changed to increase (step S13: NO) and proceeds to processing of step S17. A positive time differential of the torque command value (i.e., an increase in the torque command value τ ^* ) is a command to increase the torque of the motor 20. A negative time differential of the torque command value (i.e., a decrease in the torque command value) is a command to decrease the torque of the motor 20. A zero time differential of the torque command value (i.e., maintaining the current torque command value) is a command to maintain the torque of the motor 20 at a current constant value.

In step S14, the switching unit 14 switches the drive of the motor 20 to the square wave voltage drive, and proceeds to processing in step S15. Thus, in the processing flow of steps S13 and S14, when the torque command value τ ^* changes from a value that reduces or maintains the torque of the motor 20 at a constant value to a value that increases the torque, the switching unit 14 causes the drive unit 11 to switch the drive of the motor 20 from the vector control drive to the square wave voltage drive. Hereinafter, when a positive determination (i.e., a "YES" determination) is made in all the processing from step S11 to step S13, the square wave voltage drive switched to as the drive of the motor 20 may be referred to as "low speed drive".

In step S15, the switching unit 14 determines whether or not the signal level of the hall detection signal Hu (see FIG. 1) input from the hall sensor 22u provided on the motor 20 has changed. If the switching unit 14 determines that the signal level of the hall detection signal Hu has changed (step S15: YES), the switching unit 14 proceeds to processing in step S16. On the other hand, if the switching unit 14 determines that the signal level of the hall detection signal Hu has not changed (step S15: NO), the switching unit 14 proceeds to processing in step S17.

In step S16, the switching unit 14 instructs the drive unit 11 to end driving the motor 20 with the rectangular wave voltage drive, and the process proceeds to step S17.

In step S17, the switching unit 14 determines whether the rotation speed ω included in the rotation speed signal Sω input from the rotation speed calculation unit 13 is smaller than the drive switching threshold ωthc. The process of step S17 is executed to determine whether the drive of the motor 20 is switched to either square wave voltage drive or vector control drive under a situation in which the condition for driving the motor 20 at low speed drive is not satisfied or under a situation in which the low speed drive is terminated. The drive switching threshold ωthc is a threshold for determining whether the drive of the motor 20 is switched to either square wave voltage drive or vector control drive, and is set in the switching unit 14. The drive switching threshold ωthc is set to a value, for example, smaller than the threshold ωth used in the process of step S12. If the switching unit 14 determines that the rotation speed ω is lower than the drive switching threshold ωthc (step S17: YES), the process proceeds to step S18. On the other hand, if the switching unit 14 determines that the rotation speed ω is equal to or greater than the drive switching threshold ωthc (step S17: NO), the processing proceeds to step S19.

In step S18, the switching unit 14 causes the drive unit 11 to switch the drive of the motor 20 to the rectangular wave voltage drive, and the process proceeds to step S20.
In step S19, the switching unit 14 causes the drive unit 11 to switch the drive of the motor 20 to vector control drive, and the process proceeds to step S20.

In this way, after driving the motor 20 by the low-speed drive, which is the square wave voltage drive switched based on the change in the torque command value τ ^* (flow from step S13 to step S14), the switching unit 14 ends the driving of the motor 20 by the low-speed drive on condition that the signal level of the Hall detection signal Hu indicating the rotational position of the rotor 23 provided in the motor 20 has changed (step S16). The switching unit 14 switches the driving of the motor 20 to the square wave voltage drive or the vector control drive according to the rotational speed ω at the time when the low-speed drive is ended (flow from step S17 to step S18 or step S19).

Square wave voltage drive switches the current flow pattern based on changes in the Hall detection signal, so it has the advantage that it is possible to control current flow even in areas where it is not possible to calculate the rotation speed based on the inter-pulse time at extremely low rotation speeds. On the other hand, square wave voltage drive has the disadvantage that it is difficult to achieve high efficiency.

Vector control drive has the advantage that it theoretically eliminates torque pulsation in the motor and is superior to square wave voltage drive in terms of noise, vibration, efficiency, torque accuracy, and transient characteristics. On the other hand, vector control drive has the disadvantage that it requires a controller with high computing power because it uses pulse width modulation (PWM) control to generate sinusoidal U-phase current, V-phase current, and W-phase current with little distortion.

As such, square wave voltage driving and vector control driving each have advantages and disadvantages. Therefore, the motor control device 10 selects, as the drive of the motor 20, between square wave voltage driving and vector control driving, whichever is more suitable for the rotation speed ω of the motor 20 after low-speed driving has been performed. In this way, the motor control device 10 can control the motor 20 after low-speed driving has been performed by utilizing the respective advantages of square wave voltage driving and vector control driving.

In step S20, it is determined whether the power supply for operating the motor control device 10 is off. If the voltage value of the power supply input to the motor control device 10 is lower than a predetermined value (step S20: YES), the motor control device 10 determines that the power supply is off and ends operation. On the other hand, if the voltage value of the power supply input to the motor control device 10 is equal to or higher than a predetermined value (step S20: NO), the motor control device 10 determines that the power supply is not off and returns to the processing of step S11.

[Operation Timing of Motor Control Device]
Fig. 4 is a timing chart showing an example of the operation timing of the motor control device 10. In Fig. 4, the passage of time is represented from left to right.

During a period P1 shown in Fig. 4, the motor control device 10 drives the motor 20 by vector control drive by the drive unit 11 in order to make the torque of the motor 20 follow the torque command value τ ^* generated by the command unit 15. Therefore, as shown in Fig. 4, the rotation speed ω of the motor 20 decreases over time. As the rotation speed ω of the motor 20 decreases, the periods of the Hall detection signals Hu, Hv, and Hw detected by the Hall sensors 22u, 22v, and 22w (see Fig. 1) provided on the motor 20 also become longer over time. The period P1 corresponds to the flow of "YES in step S11 → YES in step S12 → NO in step S13 → NO in step S17 → step S19" shown in Fig. 3.

Now, vector control driving in the driving unit 11 and position detection in the detection unit 12 (see FIG. 1) will be described with reference to FIG. 5 and FIG. 6. FIG. 5 is a diagram showing an example of the voltage waveforms of the U-phase AC voltage Vu, the V-phase AC voltage Vv, and the W-phase AC voltage Vw output to the motor 20 by the driving unit 11 in which the driving of the motor 20 is switched to vector control driving by the switching unit 14, and an example of the voltage waveforms of the Hall detection signals Hu, Hv, and Hw output from the Hall sensors 22u, 22v, and 22w. FIG. 6 is a diagram showing an example of the voltage waveforms of the Hall detection signals Hu, Hv, and Hw shown in FIG. 5, and a diagram showing an example of the relationship between the combination of the Hall detection signals Hu, Hv, and Hw in position detection using 6-step angle calculation and the rotation angle θ of the motor 20.

A vector control drive unit 112 (see FIG. 1) that executes vector control drive generates pulse signals Pbu to Pbz (see FIG. 1) for making the U-phase current Iu, V-phase current Iv, and W-phase current Iw input from the inverter unit 113 (see FIG. 1) follow the d-axis current command value Id ^* and q-axis current command value Iq ^* input from the command unit 15, and outputs the pulse signals to the inverter unit 113. The d-axis current command value Id ^* and the q-axis current command value Iq ^* are generated based on the torque command value τ ^* . Therefore, the vector control drive unit 112 makes the U-phase current Iu, V-phase current Iv, and W-phase current Iw follow the d-axis current command value Id ^* and the q-axis current command value Iq ^* , so that the motor 20 operates so that the torque follows the torque command value τ ^* .

In vector control driving, the pulse signals Pbu to Pbz input from the vector control driving unit 112 control the switching of the six semiconductor elements Qu to Qz (see FIG. 2) provided in the inverter unit 113 in a control pattern in which the high side of one phase is turned on, the low side of the other phase is turned on, and both sides of the remaining phases are turned off. As a result, as shown in FIG. 5, the U-phase AC voltage Vu, the V-phase AC voltage Vv, and the W-phase AC voltage Vw become sinusoidal signals whose one cycle coincides with the period during which the electrical angle θe rotates 360° (i.e., one cycle of the electrical angle θe). The U-phase AC voltage Vu, the V-phase AC voltage Vv, and the W-phase AC voltage Vw become signals whose electrical angles θe are shifted by 120° from each other.

The drive unit 11 repeatedly executes vector control drive so that the U-phase current Iu, V-phase current Iv, and W-phase current Iw input from the inverter unit 113 follow the d-axis current command value Id ^* and q-axis current command value Iq ^* input from the switching unit 14, and the rotational speed ω and torque of the motor 20 approach desired values.

As shown in FIG. 5, the Hall detection signal Hu output from the Hall sensor 22u has a period that matches the period of the U-phase AC voltage Vu, and is a square wave signal that is positive when the U-phase AC voltage Vu is positive and 0 V when the U-phase AC voltage Vu is negative. The Hall detection signal Hv output from the Hall sensor 22v has a period that matches the period of the V-phase AC voltage Vv, and is a square wave signal that is positive when the V-phase AC voltage Vv is positive and 0 V when the V-phase AC voltage Vv is negative. The Hall detection signal Hw output from the Hall sensor 22w has a period that matches the period of the W-phase AC voltage Vw, and is a square wave signal that is positive when the W-phase AC voltage Vw is positive and 0 V when the W-phase AC voltage Vw is negative.

The Hall sensors 22u, 22v, and 22w provided on the motor 20 are arranged at 120° intervals, shifted by 60° from the U-phase winding 21u, the V-phase winding 21v, and the W-phase winding 21w (see FIG. 1). Therefore, as shown in FIG. 5 and FIG. 6, the Hall detection signal Hu output from the Hall sensor 22u, the Hall detection signal Hv output from the Hall sensor 22v, and the Hall detection signal Hw output from the Hall sensor 22w have signal waveforms whose phases are shifted by 120° from each other. In addition, one period of the Hall detection signals Hu, Hv, and Hw coincides with one period of the electrical angle θe of the motor 20.

As shown in FIG. 6, the detection unit 12 determines the electrical angle θe in a stepped manner, for example, as stages E1, E2, E3, E4, E5, and E6, depending on the combination of the voltage levels of the Hall detection signals Hu, Hv, and Hw. For example, when the voltage level of the Hall detection signal Hu is high, the voltage level of the Hall detection signal Hv is low, and the voltage level of the Hall detection signal Hw is high, the detection unit 12 determines the electrical angle θe to be 0° (360°) as stage E1. For example, when the voltage level of the Hall detection signal Hu is high, the voltage level of the Hall detection signal Hv is low, and the voltage level of the Hall detection signal Hw is low, the detection unit 12 determines the electrical angle θe to be 60° as stage E2. Note that in FIG. 4, the symbols "E1 to E6" representing the stages of the electrical angle θe are shown during the period P1 and a part of the period P3 described later.

The detection unit 12 detects the rotation angle θ of the rotor 23 in a stepped manner from 0° to 360° (0°) based on the electrical angle θe determined in this manner. The detection unit 12 detects the rotation angle θ of the motor 20 using the above-mentioned formula (1).

Returning to FIG. 4, at time t1 after a predetermined period has elapsed in period P1, the torque command value τ* input to the switching unit 14 changes to increase, and the switching unit 14 causes the drive unit 11 to switch the operation of the motor 20 to square wave voltage drive.

Here, the rectangular wave voltage drive in the drive unit 11 will be described with reference to FIG. 7. FIG. 7 is a diagram that shows an example of the voltage waveforms of the U-phase AC voltage Vu, the V-phase AC voltage Vv, and the W-phase AC voltage Vw output to the motor 20 by the drive unit 11 after the switching unit 14 has switched the drive of the motor 20 to rectangular wave voltage drive, and an example of the voltage waveforms of the Hall detection signals Hu, Hv, and Hw output from the Hall sensors 22u, 22v, and 22w.

The rectangular wave voltage drive unit 111 (see FIG. 1) that performs the rectangular wave voltage drive generates pulse signals Pau to Paz (see FIG. 1) that are input to the inverter unit 113 as pulse signals Pu to Pz. The pulse signals Pau to Paz are signals for outputting the U-phase AC voltage Vu, V-phase AC voltage Vv, and W-phase AC voltage Vw from the inverter unit 113 to the motor 20 according to the excitation patterns of the U-phase winding 21u, V-phase winding 21v, and W-phase winding 21w that correspond to the rotation angle θ of the motor 20. In the rectangular wave voltage drive, the switching of the six semiconductor elements Qu to Qz provided in the inverter unit 113 is controlled by the pulse signals Pau to Paz input from the rectangular wave voltage drive unit 111 as the pulse signals Pu to Pz, in the same manner as in the vector control drive. As a result, as shown in FIG. 7, the U-phase AC voltage Vu, the V-phase AC voltage Vv, and the W-phase AC voltage Vw become positive pulse signals during a 120° period during which the electrical angle θe rotates 360°, become constant 0 V signals during the next 60° period, become negative pulse signals during the next 120° period, and become constant 0 V signals during the final 60° period. The U-phase AC voltage Vu, the V-phase AC voltage Vv, and the W-phase AC voltage Vw become signals with electrical angles θe shifted by 120° from each other.

The pulse signals Pau to Paz generated by the rectangular wave voltage driver 111 are also signals for making the U-phase current Iu, V-phase current Iv, and W-phase current Iw input from the inverter 113 follow the q-axis current command value Iq ^* input from the command unit 15. The q-axis current command value Iq ^* is generated based on the torque command value τ ^* . Therefore, the rectangular wave voltage driver 111 makes the U-phase current Iu, V-phase current Iv, and W-phase current Iw follow the q-axis current command value Iq ^* , so that the motor 20 operates so that the torque follows the torque command value τ ^* . The inverter 113 repeatedly operates by such pulse signals Pau to Paz, so that the duty ratios of the rectangular pulse-shaped U-phase AC voltage Vu, V-phase AC voltage Vv, and W-phase AC voltage Vw change. As a result, the rotation speed ω and torque of the motor 20 approach desired values.

As shown in Figures 6 and 7, the Hall detection signals Hu, Hv, and Hw in square wave voltage drive have the same signal waveforms as the Hall detection signals Hu, Hv, and Hw in vector control drive. Therefore, even if the motor 20 is driven by square wave voltage drive, the detection unit 12 can detect the rotational position (i.e., rotational angle) of the rotor 23 in the same manner as in the case of vector control drive.

Returning to FIG. 4, the period P2 from time t1 to time t2 when the Hall detection signal Hu rises for the first time after time t1 corresponds to the flow of "YES in step S11 → YES in step S12 → YES in step S13 → step S14 → step S15" shown in FIG. 3. At time t2, the Hall detection signal Hu rises and the signal level changes, so the switching unit 14 causes the drive unit 11 to end the operation of the motor 20 driven by the square wave voltage.

In a period P3 after time t2, the motor control device 10 controls the motor 20 by switching the drive of the motor 20 between a rectangular wave voltage drive and a vector control drive depending on the magnitude relationship between the rotation speed ω of the motor 20 and the threshold value ωth and the drive switching threshold value ωthc. In other words, when the rotation speed ω of the motor 20 is smaller than the drive switching threshold value ωthc, the period P3 corresponds to the flow of "NO in step S11 → YES in step S17 → step S18 → step S20". Also, when the rotation speed ω of the motor 20 is equal to or greater than the drive switching threshold value ωthc, the period P3 corresponds to the flow of "NO in step S11 → NO in step S17 → step S19 → step S20".

When the motor 20 is driven by vector control drive, if the torque command value τ ^* changes in a state in which the rotation speed ω of the motor 20 is lower than the threshold value ωth, the motor control device 10 can drive the motor 20 by square wave voltage drive (flow from step S11 to step S14 shown in FIG. 3). This allows the motor control device 10 to suppress the motor 20 from being locked by forcibly rotating the motor 20 by square wave voltage drive. As a result, the motor control device 10 can control the motor 20 so that the rotation speed ω of the motor 20 follows the rotation speed corresponding to the change in the torque command value τ ^* .

Assume that a power control unit (not shown) provided in a vehicle 1 (see FIG. 1 ) and controlling a motor control device 10 recognizes the control of the motor 20 in a processing order such as "sudden deceleration → stop → acceleration." In this case, even if the rotation speed (in other words, the number of rotations) of the motor 20 in the processing order recognized by the power control unit deviates from the actual rotation speed of the motor 20, the motor control device 10 drives the motor 20 with a square wave voltage drive in period P2, thereby preventing the motor 20 from locking or rotation failure of the motor 20. Furthermore, by driving the motor 20 with a square wave voltage drive in period P2, the motor control device 10 can control the motor 20 in a direction that reduces the deviation between the rotation speed in the processing order and the actual rotation speed.

4. Other embodiments
The drive unit 11 may be configured to stop the operation of the non-selected one of the rectangular wave voltage drive unit 111 and the vector control drive unit 112. This allows the motor control device 10 to reduce the processing load.

In step S13 shown in FIG. 3, the switching unit 14 uses whether the torque command value τ ^* has changed as a criterion for judgment, but the amount of change in the torque command value τ ^* may also be used as a criterion for judgment. For example, the rate of change in ^the torque command value τ ^* (i.e., the time differential value of the torque command value τ ^* ) may be used as the amount of change in the torque command value τ ^* . Specifically, the switching unit 14 may switch the drive of the motor 20 from vector control drive to square wave voltage drive when the amount of change in the torque command value τ * is equal to or greater than a predetermined value (predetermined threshold value) (flow from step S13 to step S14 shown in FIG. 3). As a result, even if the torque command value τ ^* changes slightly due to erroneous detection of the Hall detection signal Hu due to noise or the like, the switching unit 14 can determine that the torque command value τ ^* has not changed in the process of step S13. For this reason, the motor control device 10 can stabilize the drive of the motor 20 at low rotation speed.

In the process of step S15 shown in FIG. 3, the switching unit 14 uses the first change in the Hall detection signal after the start of low-speed drive as the judgment criterion, but it is not necessary to judge the change in the Hall detection signal until a predetermined period has elapsed since the start of low-speed drive. This allows the motor control device 10 to reliably secure the period during which the motor 20 is driven in low-speed drive, thereby preventing the motor 20 from locking or malfunctioning.

In the motor control device 10, the same Hall detection signal is used to calculate the rotation speed ω of the motor 20 and to detect changes in the signal level during low-speed driving, but different Hall detection signals may be used.

4. Configurations supported by the above embodiment
The above embodiment is a specific example of the following configuration.

(Configuration 1) A motor control device comprising: a drive unit capable of selectively driving a motor by rectangular wave voltage drive, which applies a rectangular wave voltage to a stator winding provided in the motor to drive the motor, and vector control drive, which applies a sinusoidal wave voltage to the stator winding to drive the motor; a command unit that commands a torque command value that tracks the torque of the motor; and a switching unit that causes the drive unit to switch the drive of the motor to the rectangular wave voltage drive or the vector control drive, wherein the switching unit switches the drive of the motor from the vector control drive to the rectangular wave voltage drive when the torque command value input from the command unit changes while the motor is being driven by the vector control drive at a rotational speed equal to or lower than a threshold value.
According to the motor control device of configuration 1, even if the rotation speed of the motor suddenly drops, the motor can be forcibly rotated by driving it with a square wave voltage, thereby suppressing vibration of the motor. As a result, the motor control device of configuration 1 can achieve stabilization of the motor output at low rotation speeds, which in turn can contribute to improving energy efficiency.

(Configuration 2) The motor control device described in Configuration 1, wherein the switching unit drives the motor using low-speed drive, which is the rectangular wave voltage drive switched based on a change in the torque command value, and then, on condition that a signal level of a position signal indicating the rotational position of a rotor provided in the motor has changed, ends the driving of the motor using the low-speed drive, and switches the driving of the motor to the rectangular wave voltage drive or the vector control drive depending on the rotational speed at the time the low-speed drive is ended.
According to the motor control device of configuration 2, an appropriate motor drive method is selected according to the motor rotation speed even after low-speed drive has been performed, so that the motor can be driven efficiently even after it is rotated again.

(Configuration 3) The motor control device according to configuration 1 or 2, wherein the switching unit switches the drive of the motor from the vector control drive to the rectangular wave voltage drive when an amount of change in the torque command value is equal to or greater than a predetermined value.
According to the motor control device of configuration 3, slight changes in the torque command value resulting from erroneous detection of the position signal due to noise or the like are no longer judged to be changes in the torque command value, thereby stabilizing the drive of the motor at low rotation speeds.

(Configuration 4) A motor control device described in any one of configurations 1 to 3, wherein the switching unit switches the drive of the motor from the vector control drive to the rectangular wave voltage drive when the torque command value changes from a value that reduces or maintains the torque at a constant value to a value that increases the torque.
According to the motor control device of configuration 4, when the motor is rotating at a low speed, it is possible to prevent the motor from being locked by forcibly rotating the motor by driving it with a square wave voltage .

(Configuration 5) A vehicle comprising: the motor control device according to any one of configurations 1 to 4; the motor; and a position detection unit that outputs a position signal indicating a rotational position of a rotor provided in the motor.
According to the vehicle of configuration 5, the same effects as those of the motor control device of configurations 1 to 4 can be obtained.

1...vehicle, 10...motor control device, 11...drive unit, 12...detection unit, 13...rotational speed calculation unit, 14...switching unit, 15...command unit, 20...motor, 21u...U-phase winding, 21v...V-phase winding, 21w...W-phase winding, 22u, 22v, 22w...Hall sensor, 23...rotor, 111...rectangular wave voltage drive unit, 112...vector control drive unit, 113...inverter unit, 113u...U-phase arm, 113v...V-phase arm, 113w...W-phase arm, E1 to E6...stage, Hu, Hv, Hw...Hall detection signal, Id ^* ...d-axis current command value, Iq ^* ...q-axis current command value, Iu...U-phase current, Iv...V-phase current, Iw...W-phase current, Ln...positive line, Lp...negative line, P1, P2, P3...period, Pau to Paz, Pbu to Pbz, Pu to Pz...pulse signal, Qu to Qz...semiconductor element, Scd1, Scd2...drive switching signal, Sθ...rotation angle signal, Sω...rotation speed signal, Vu...U-phase AC voltage, Vv...V-phase AC voltage, Vw...W-phase AC voltage, θ...rotation angle, τ ^* ...torque command value, ω...rotation speed

Claims (5)

a drive unit (11) capable of selectively driving the motor (20) by a rectangular wave voltage drive that applies a rectangular wave voltage to stator windings (21u, 21v, 21w) provided in the motor (20) to drive the motor (20) and a vector control drive that applies a sinusoidal wave voltage to the stator windings (21u, 21v, 21w) to drive the motor (20);
A command unit (15) that outputs a torque command value (τ ^* ) that commands the torque of the motor (20) ;
A switching unit (14) that switches the drive of the motor (20) to the rectangular wave voltage drive or the vector control drive by the drive unit (11);
Equipped with
The switching unit (14) is
When the motor (20) is controlled by the vector control drive, if the rotation speed (ω) of the motor becomes equal to or lower than a threshold value (ωth) and then the torque command value (τ ^* ) input from the command unit (15) changes to a value instructing an increase in torque, the drive of the motor (20) is switched from the vector control drive to the rectangular wave voltage drive,
after driving the motor (20) by the low-speed drive, which is the square wave voltage drive switched based on the change in the torque command value (τ ^* ), on condition that a signal level of a position signal indicating a rotational position of a rotor (23) provided in the motor (20) has changed, the driving of the motor (20) by the low-speed drive is terminated, and the driving of the motor (20) is switched to the square wave voltage drive or the vector control drive according to the rotational speed (ω) at the time when the low-speed drive is terminated .
A motor control device (10). a drive unit (11) capable of selectively driving the motor (20) by a rectangular wave voltage drive that applies a rectangular wave voltage to stator windings (21u, 21v, 21w) provided in the motor (20) to drive the motor (20) and a vector control drive that applies a sinusoidal wave voltage to the stator windings (21u, 21v, 21w) to drive the motor (20);
A command unit (15) that outputs a torque command value (τ ^* ) that commands the torque of the motor (20) ;
A switching unit (14) that switches the drive of the motor (20) to the rectangular wave voltage drive or the vector control drive by the drive unit (11);
Equipped with
The switching unit (14) is
When the motor (20) is controlled by the vector control drive, if the rotation speed (ω) of the motor becomes equal to or lower than a threshold value (ωth) and then the torque command value (τ ^* ) input from the command unit (15) changes to a value instructing an increase in torque, the drive of the motor (20) is switched from the vector control drive to the rectangular wave voltage drive,
When a torque increase amount commanded in the change of the torque command value (τ ^* ) is equal to or greater than a predetermined value, the drive of the motor (20) is switched from the vector control drive to the rectangular wave voltage drive .
A motor control device (10). The change in the torque command value (τ ^* ) is a change from a value that reduces or maintains the torque at a constant value to a value that increases the torque.
The motor control device (10) of claim 1. The torque command value (τ ^* ) from a value that reduces or keeps the torque constant to a value that increases the torque,
The motor control device (10) of claim 2. A motor control device (10) according to any one of claims 1 to 4,
The motor (20);
a position detection unit (22u, 22v, 22w) that outputs position signals (Hu, Hv, Hw) that indicate a rotational position of a rotor (23) provided in the motor (20);
A vehicle equipped with.

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