Motor control device and vehicle

Abstract

To provide a motor control unit and a vehicle that can provide a stable motor output during low-speed rotation.SOLUTION: A motor control unit (10) comprises a drive section (11) that can selectively drive a motor (20) with rectangular wave voltage driving and vector control driving, a command section (15) that commands a torque command value (τ*) to be followed by the torque of the motor (20), and a switching section (14) that brings the drive section (11) switching the drive of the motor (20) to the rectangular wave voltage driving or the vector control driving. The switching section (14) brings the drive section (11) switching the drive of the motor (20) to the rectangular wave voltage driving from the vector control driving when the torque command value (τ*) entered from the command section (15) is changed during the motor (20) is driven at a revolution speed of the threshold value or lower with the vector control driving.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a motor control device and a vehicle.

Background Art

[0002] In recent years, efforts to realize a low-carbon society or a decarbonized society have been active, and research and development on electrification technologies have been carried out in vehicles in order to reduce CO2 emissions and improve energy efficiency. As one of these electrification technologies, a technology for driving a motor provided in a vehicle by applying a drive voltage having a predetermined voltage waveform is known.

[0003] Patent Document 1 discloses a technique for performing rectangular wave energization drive when the rotational speed of a DC motor is less than a threshold value and performing sine wave energization drive when the rotational speed of the DC motor is equal to or greater than the threshold value. By the technique disclosed in Patent Document 1, it is possible to avoid the braking operation at the time of phase switching during motor startup and suppress the reduction of the startup torque.

[0004] Patent Document 2 discloses a technique for calculating the rotational 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 pulse-shaped position sensor signal detected by each hall sensor provided in the brushless motor. By the technique disclosed in Patent Document 2, it is possible to reduce the calculation error of the rotational speed generated by the variation in the mounting position of each hall sensor, and a brushless motor with smooth rotation and low noise can be realized.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] By the way, in the drive technology of a motor, which is one of the technologies related to electrification technology, , low there is a problem that the motor output during rotation is unstable.

[0007] This application 、 is for solving the above problem, In particular, during re-acceleration after sudden deceleration and aims to achieve stabilization of the motor output at low rotation speeds when re-accelerating and, by extension, contributes to improving energy efficiency.

Means for Solving the Problem

[0008] One aspect for achieving the above object is a drive unit capable of selectively driving the motor by applying a rectangular wave voltage to a stator winding provided in the motor for rectangular wave voltage drive and applying a sine wave voltage to the stator winding for vector control drive to drive the motor, a command unit that outputs a torque command value indicating the torque of the motor, and a switching unit that causes the drive unit to switch the drive of the motor between the rectangular wave voltage drive and the vector control drive. When the motor is controlled by the vector control drive, after the rotational speed (ω) of the motor becomes equal to or lower than a threshold value, when the torque command value (τ * ) input from the command unit changes to a value indicating an increase in torque, the drive of the motor is switched from the vector control drive to the rectangular wave voltage drive , after driving the motor by low-speed driving which is the rectangular wave voltage drive switched based on the change of the torque command value, on the condition that the signal level of the position signal indicating the rotational position of the rotor provided in the motor has changed, end the driving of the motor by the low-speed driving, and according to the rotational speed (ω) at the time when the low-speed driving is ended, switch the driving of the motor to the rectangular wave voltage drive or the vector control drive It is a motor control device. Another aspect for achieving the above object is a drive unit capable of selectively driving the motor by a rectangular wave voltage drive for applying a rectangular wave voltage to a stator winding provided in the motor to drive the motor and a vector control drive for applying a sine wave voltage to the stator winding to drive the motor, a command unit for outputting a torque command value for instructing the torque of the motor, and a switching unit for switching the driving of the motor by the drive unit to the rectangular wave voltage drive or the vector control drive. When the motor is controlled by the vector control drive, after the rotational speed (ω) of the motor becomes equal to or lower than a threshold value, when the torque command value (τ * ) input from the command unit changes to a value indicating an increase in torque, switch the driving of the motor from the vector control drive to the rectangular wave voltage drive, and when the amount of torque increase indicated by the change in the torque command value is equal to or greater than a predetermined value, switch the driving of the motor from the vector control drive to the rectangular wave voltage drive. This is a motor control device.

[0009] Also, for achieving the above object Furthermore another aspect is a vehicle including the motor control device according to the above aspect, or the above 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.

Advantages of the Invention

[0010] According to the above aspect, stabilization of the motor output at low rotation speeds can be achieved.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0012] [1. Configuration of Motor Control Device and Vehicle] FIG. 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 a motor control device 10, a motor 20 controlled by the motor control device 10, and a plurality of hall sensors (an example of a position detection unit) 22u, 22v, 22w that output hall detection signals (an example of position signals) Hu, Hv, Hw indicating the rotational position of a rotor 23 provided in the motor 20. Examples of the vehicle 1 include an automobile and a motor-assisted bicycle.

[0013] The motor 20 is composed of, 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 (all of which are examples of stator windings). 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, 22w are arranged at 120° intervals in a state shifted by 60° from the U-phase winding 21u, the V-phase winding 21v, and the W-phase winding 21w. In the present 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.

[0014] Next, the configuration of the motor control device 10 will be described with reference to FIGS. 1 and 2. As shown in FIG. 1, the motor control device 10 includes a drive unit 11 connected to the U-phase winding 21u, the V-phase winding 21v, and the W-phase winding 21w provided in the motor 20. The motor control device 10 includes a detection unit 12 connected to the hall sensors 22u, 22v, 22w provided in 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.

[0015] The driving unit 11 is configured to selectively drive the motor 20 by a rectangular wave voltage driving in which a rectangular wave voltage is applied 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 driving in which a sinusoidal wave voltage is applied to the U-phase winding 21u, the V-phase winding 21v, and the W-phase winding 21w to drive the motor 20. The driving unit 11 has a rectangular wave voltage driving unit 111, a vector control driving unit 112, and an inverter unit 113. The rectangular wave voltage driving 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 driving 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 a drive switching signal Scd2 input from the switching unit 14. The rectangular wave voltage driver 111 and the vector control driver 112 are electrically disconnected from the input of the inverter unit 113 by putting the outputs into a high impedance state, for example.

[0016] When the switching unit 14 switches the drive unit 11 to operate using the square wave voltage drive unit 111, the drive unit 11 drives the motor 20 with square wave voltage drive using the square wave voltage drive unit 111 and the inverter unit 113. On the other hand, when the switching unit 14 switches the drive unit 11 to operate using the vector control drive unit 112, the drive unit 11 drives the motor 20 with vector control drive using the vector control drive unit 112 and the inverter unit 113.

[0017] The rectangular wave voltage driver 111 drives the q-axis current command value Iq * The detector 12 generates pulse signals Pau, Pav, Paw, Pax, Pay, and Paz for driving the inverter unit 113, using a U-phase current Iu, a V-phase current Iv, and a W-phase current Iw input from the inverter unit 113, and a rotation angle signal Sθ of the motor 20 input from the detector 12. Hereinafter, the "pulse signals Pau, Pav, Paw, Pax, Pay, and Paz" may be abbreviated as "pulse signals Pau to Paz".

[0018] The vector control drive unit 112 receives the d-axis current command value Id input from the command unit 15 * and the q-axis current command value Iq * , and uses the U-phase current Iu, V-phase current Iv, and W-phase current Iw input from the inverter unit 113 and the rotation angle signal Sθ input from the detection unit 12 to generate pulse signals Pbu, Pbv, Pbw, Pbx, Pby, and Pbz for driving the inverter unit 113. Hereinafter, "pulse signals Pbu, Pbv, Pbw, Pbx, Pby, and Pbz" may be abbreviated as "pulse signals Pbu~Pbz".

[0019] When the drive unit 11 is switched by the switching unit 14 to drive the motor 20 with a rectangular wave voltage, the drive unit 11 inputs the pulse signals Pau, Pav, Paw, Pax, Pay, and Paz to the inverter unit 113 as the pulse signals Pu, Pv, Pw, Px, Py, and Pz. When the drive unit 11 is switched by the switching unit 14 to drive the motor 20 with vector control, the drive unit 11 inputs the pulse signals Pbu, Pbv, Pbw, Pbx, Pby, and Pbz to the inverter unit 113 as the pulse signals Pu, Pv, Pw, Px, Py, and Pz. Hereinafter, "pulse signals Pu, Pv, Pw, Px, Py, and Pz" may be abbreviated as "pulse signals Pu~Pz".

[0020] Figure 2 shows an example of the circuit configuration of the inverter unit 113. As shown in FIG. 2, the inverter unit 113 is configured by full-bridge connecting six semiconductor elements Qu, Qv, Qw, Qx, Qy, and Qz between a positive electrode side line Lp to which a positive electrode side DC voltage is applied and a negative electrode side line Ln to which a negative electrode side DC voltage is applied. Hereinafter, "semiconductor elements Qu, Qv, Qw, Qx, Qy, Qz" may be abbreviated as "semiconductor elements Qu~Qz". The semiconductor elements Qu and Qx are connected in series between the positive electrode side line Lp and the negative electrode side line Ln to form a U-phase arm 113u. The semiconductor elements Qv and Qy are connected in series between the positive electrode side line Lp and the negative electrode side line Ln to form a V-phase arm 113v. The semiconductor elements Qw and Qz are connected in series between the positive electrode side line Lp and the negative electrode side line Ln to form a W-phase arm 113w. The semiconductor elements Qu~Qz have a power semiconductor element and a freewheeling diode connected in anti-parallel to the power semiconductor element.

[0021] 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~Qz are turned on / off controlled in a predetermined timing and in a predetermined order by the pulse signals Pu~Pz. Thereby, the U-phase arm 113u outputs a U-phase AC voltage Vu from the connection portion 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 portion of 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 portion of the semiconductor elements Qw and Qz to the W-phase winding 21w provided in the motor 20.

[0022] When the inverter unit 113 operates, the 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, the 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 the 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.

[0023] Returning to FIG. 1, the command unit 15 controls the torque of the motor 20 indicate Torque command value τ * as output. Based on the rotational speed of the motor 20 calculated by the rotational speed calculation unit 13, the rotational speed command value input from the outside, and the accelerator opening degree input from the outside, the command unit 15 generates the torque command value τ * In addition, 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 generates the d-axis current command value Id * and the q-axis current command value Iq * 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 the q-axis current command value Iq * to the vector control drive unit 112.

[0024] The detection unit 12 detects the rotational position (i.e., the 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 the combination of the 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. Assuming that 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 equation (1). θ = θe × 2 / p ···(1)

[0025] 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.

[0026] The switching unit 14 causes the drive unit 11 to switch the drive of the motor 20 between rectangular wave voltage drive and vector control drive. Although details will be described later, the switching unit 14, when the torque command value τ * input from the command unit 15 changes while the motor 20 is being driven at a rotational speed below the threshold value by vector control drive, causes the drive of the motor 20 to be switched from vector control drive to rectangular wave voltage drive. By the switching unit 14 switching the drive of the motor 20 for the drive unit 11 based on the drive and rotational speed of the motor 20, the motor control device 10 can achieve stabilization of the output of the motor 20 during low rotation.

[0027] When the switching unit 14 outputs the drive switching signal Scd1 to the rectangular wave voltage drive unit 111, it determines that the drive of the motor 20 is rectangular wave voltage drive. When it outputs the drive switching signal Scd2 to the vector control drive unit 112, it determines that the drive of the motor 20 is vector control drive. The switching unit 14 acquires the rotational speed ω of the motor 20 from the rotational speed signal Sω input from the rotational speed calculation unit 13.

[0028] The switching unit 14 receives the hall detection signal Hu output from the hall sensor 22u provided in the motor 20. Although details will be described later, when the switching unit 14 switches the drive of the motor 20 to rectangular wave voltage drive for stabilizing the output of the motor 20 at low rotation, it determines whether to end the rectangular wave voltage drive based on the change in the signal level of the hall detection signal Hu.

[0029] When the switching unit 14 drives the motor 20 with rectangular wave voltage drive, it 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 switching unit 14 drives the motor 20 with vector control drive, it 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. For this reason, 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, the pulse signals Pau~Paw and the pulse signals Pbu~Pbw do not interfere with each other, and only one of the pulse signals can be input to the inverter unit 113 as the pulse signals Pu~Pw.

[0030] The rotation speed calculation unit 13 calculates the rotation speed ω of the motor 20 based on any one of the plurality of hall detection signals Hu, Hv, and Hw. In the present embodiment, the rotation speed calculation unit 13 calculates the rotation speed ω of the motor 20 (more specifically, the rotational angular velocity 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. Assuming that the number of magnetic poles of the permanent magnet provided on 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 according to 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)

[0031] [2. Operation of the motor control device] [2-1. Flow of operation of the motor control device] The operation of the motor control device 10 according to the present embodiment will be described with reference to FIGS. 3 to 7 while referring to FIGS. 1 and 2. FIG. 3 is a flowchart showing an example of the flow of operation of the motor control device 10. The process shown in FIG. 3 is started, for example, when the power supply to the motor control device 10 is turned on (i.e., the power supply is in the on state).

[0032] As shown in FIG. 3, when the motor control device 10 (see FIG. 1) starts controlling the motor 20, in step S11, the switching unit 14 (see FIG. 1) determines whether the drive of the motor 20 is vector control drive. When the switching unit 14 outputs the drive switching signal Scd2 to the vector control drive unit 112 (step S11: YES), it determines that the drive of the motor 20 is vector control drive and proceeds to the process of step S12. On the other hand, when the switching unit 14 outputs the drive switching signal Scd1 to the rectangular wave voltage drive unit 111 (step S11: NO), it determines that the drive of the motor 20 is rectangular wave voltage drive and proceeds to the process of step S17.

[0033] In step S12, the switching unit 14 determines whether the rotational speed ω of the motor 20 included in the rotational speed signal Sω input from the rotational speed calculation unit 13 (see FIG. 1) is equal to or lower than a threshold value ωth. When the switching unit 14 determines that the rotational speed ω of the motor 20 is equal to or lower than the threshold value ωth (step S12: YES), it proceeds to the process of step S13. On the other hand, when the switching unit 14 determines that the rotational speed ω of the motor 20 is greater than the threshold value ωth (step S12: NO), it proceeds to the process of step S17. The threshold value ωth is the rotational speed in the extremely low rotational region and is set to a value higher than the drive switching threshold value ωthc described later. The threshold value ωth is determined by experiments, simulations, etc., and may be set to different values for each type of vehicle 1 (see FIG. 1).

[0034] In step S13, the switching unit 14 determines 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 determines that the torque command value τ * is changing so as to increase (step S13: YES) and proceeds to the process of step S14. On the other hand, for example, if the result is negative or zero, the switching unit 14 determines that the torque command value τ * is not changing so as to increase (step S13: NO) and proceeds to the process of step S17. A positive time differentiation 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 differentiation 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 differentiation 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 constant current value.

[0035] In step S14, the switching unit 14 switches the drive of the motor 20 to rectangular wave voltage drive and proceeds to the process of step S15. Thus, in the flow of the processes of step S13 and step S14, the switching unit 14, the torque command value τ *When the value changes from a value that causes the torque of the motor 20 to decrease or be maintained at a constant value to a value that increases the torque, the drive unit 11 is caused to switch the drive of the motor 20 from vector control drive to rectangular wave voltage drive. Hereinafter, when an affirmative determination (that is, a determination of "YES") is made in all the processes from step S11 to step S13, the rectangular wave voltage drive switched as the drive of the motor 20 may be referred to as "low-speed drive".

[0036] 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 in the motor 20 has changed. When the switching unit 14 determines that the signal level of the hall detection signal Hu has changed (step S15: YES), it proceeds to the process of step S16. On the other hand, when the switching unit 14 determines that the signal level of the hall detection signal Hu has not changed (step S15: NO), it proceeds to the process of step S17.

[0037] In step S16, the switching unit 14 ends the drive of the motor 20 with rectangular wave voltage drive for the drive unit 11 and proceeds to the process of step S17.

[0038] In step S17, the switching unit 14 determines whether the rotational speed ω included in the rotational speed signal Sω input from the rotational speed calculation unit 13 is less than the drive switching threshold value ωthc. The process of step S17 is executed to determine whether to switch the drive of the motor 20 to either rectangular wave voltage drive or vector control drive in a situation where the condition for driving the motor 20 at low speed is not satisfied or in a situation where the low-speed drive has ended. The drive switching threshold value ωthc is a threshold value for determining whether to switch the drive of the motor 20 to either rectangular wave voltage drive or vector control drive, and is set in the switching unit 14. The drive switching threshold value ωthc is set to a value, for example, smaller than the threshold value ωth used in the process of step S12. When the switching unit 14 determines that the rotational speed ω is lower than the drive switching threshold value ωthc (step S17: YES), it proceeds to the process of step S18. On the other hand, when the switching unit 14 determines that the rotational speed ω is equal to or higher than the drive switching threshold value ωthc (step S17: NO), it proceeds to the process of step S19.

[0039] In step S18, the switching unit 14 causes the drive unit 11 to switch the drive of the motor 20 to rectangular wave voltage drive, and proceeds to the process of 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 proceeds to the process of step S20.

[0040] In this way, after driving the motor 20 by low-speed drive, which is rectangular wave voltage drive switched based on the change in the torque command value τ * (the flow from step S13 to step S14), when the signal level of the hall detection signal Hu indicating the rotational position of the rotor 23 provided in the motor 20 changes, the drive of the motor 20 by low-speed drive is terminated (step S16). The switching unit 14 switches the drive of the motor 20 to rectangular wave voltage drive or vector control drive according to the rotational speed ω at the time when the low-speed drive is terminated (the flow from step S17 to step S18 or step S19).

[0041] Rectangular-wave voltage drive is a control that switches the energization pattern based on changes in the Hall detection signal. Therefore, it has the advantage that energization control is possible even in a region where the rotational speed cannot be calculated based on the time between pulses at extremely low rotation speeds. On the other hand, rectangular-wave voltage drive has the disadvantage that it is difficult to achieve high efficiency.

[0042] Vector control drive has the advantage that the torque pulsation of the motor theoretically disappears and it is superior to rectangular-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 a controller with high computing power is required because sinusoidal U-phase current, V-phase current, and W-phase current with less distortion are generated by pulse-width modulation (PWM) control.

[0043] As described above, each of rectangular-wave voltage drive and vector control drive has advantages and disadvantages. Therefore, the motor control device 10 selects, as the drive for the motor 20, the one that is more suitable for the rotational speed ω of the motor 20 after executing low-speed drive among rectangular-wave voltage drive and vector control drive. Thereby, the motor control device 10 can control the motor 20 after executing low-speed drive by utilizing the respective advantages of rectangular-wave voltage drive and vector control drive.

[0044] In step S20, it is determined whether the power supply for operating the motor control device 10 is in the off state. When 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 in the off state and ends the operation. On the other hand, when the voltage value of the power supply input to the motor control device 10 is equal to or higher than the predetermined value (step S20: NO), the motor control device 10 determines that the power supply is not in the off state and returns to the process of step S11.

[0045] [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.

[0046] In the period P1 shown in FIG. 4, the motor control device 10 drives the motor 20 by vector control driving by the driving unit 11 in order to make the torque of the motor 20 follow the torque command value τ generated by the command unit 15. For this reason, as shown in FIG. 4, the rotational speed ω of the motor 20 decreases with the passage of time. Since the rotational 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 in the motor 20 also become longer with the passage of 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. * Here, the vector control drive in the drive unit 11 and the position detection in the detection unit 12 (see FIG. 1) will be described with reference to FIGS. 5 and 6. FIG. 5 is a diagram schematically showing an example of the voltage waveforms of the U-phase alternating current voltage Vu, the V-phase alternating current voltage Vv, and the W-phase alternating current voltage Vw output from the drive unit 11 whose drive of the motor 20 has been switched to vector control drive 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 schematically showing an example of the relationship between the voltage waveforms of the hall detection signals Hu, Hv, and Hw shown in FIG. 5, 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.

[0047] The 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, the V-phase current Iv, and the W-phase current Iw input from the inverter unit 113 (see FIG. 1) follow the d-axis current command value Id

[0048] input from the command unit 15 and outputs them to the inverter unit 113. The d-axis current command value Id * and the q-axis current command value Iq * are * and the q-axis current command value Iq * are *It is generated based on this. Therefore, the vector control drive unit 112 causes the U-phase current Iu, V-phase current Iv, and W-phase current Iw to follow the d-axis current command value Id * and the q-axis current command value Iq * By making the torque follow the torque command value τ * the motor 20 operates so that the torque follows.

[0049] In vector control drive, among the six semiconductor elements Qu to Qz (see Fig. 2) provided in the inverter unit 113, one phase has the high-side turned on, the other phase has the low-side turned on, and the remaining phases have both sides turned off, and the switching is controlled according to the control pattern where the remaining phases have both sides turned off. As a result, as shown in Fig. 5, the U-phase AC voltage Vu, V-phase AC voltage Vv, and W-phase AC voltage Vw become sine wave signals that coincide with one period of 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 are signals with the electrical angle θe shifted from each other by 120°.

[0050] 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 the q-axis current command value Iq * As a result, the rotational speed ω and torque of the motor 20 approach the desired values.

[0051] As shown in Fig. 5, the Hall detection signal Hu output from the Hall sensor 22u has a period that coincides with the period of the U-phase AC voltage Vu, and becomes a positive voltage when the U-phase AC voltage Vu is positive, and becomes a rectangular wave signal with 0V when the U-phase AC voltage Vu is negative. The Hall detection signal Hv output from the Hall sensor 22v has a period that coincides with the period of the V-phase AC voltage Vv, and becomes a positive voltage when the V-phase AC voltage Vv is positive, and becomes a rectangular wave signal with 0V when the V-phase AC voltage Vv is negative. The Hall detection signal Hw output from the Hall sensor 22w has a period that coincides with the period of the W-phase AC voltage Vw, and becomes a positive voltage when the W-phase AC voltage Vw is positive, and becomes a rectangular wave signal with 0V when the W-phase AC voltage Vw is negative.

[0052] The Hall sensors 22u, 22v, and 22w provided in the motor 20 are arranged at 120° intervals in a state shifted by 60° from the U-phase winding 21u, V-phase winding 21v, and W-phase winding 21w (see Fig. 1). For this reason, as shown in Figs. 5 and 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 with phases shifted from each other by 120°. Also, one period of the Hall detection signals Hu, Hv, and Hw coincides with one period of the electrical angle θe of the motor 20.

[0053] As shown in FIG. 6, the detection unit 12 determines the electrical angle θe in a stepped manner as stages E1, E2, E3, E4, E5, E6, for example, according to 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 as 0° (360°) as stage E1. Also, 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 as 60° as stage E2. In FIG. 4, reference numerals “E1 to E6” representing the stages of the electrical angle θe are shown for a part of the period P1 and the period P3 described later.

[0054] Based on the electrical angle θe determined in this way, the detection unit 12 detects the rotation angle θ of the rotor 23 in a stepped manner from 0° to 360° (0°). The detection unit 12 detects the rotation angle θ in the motor 20 using the above-described equation (1).

[0055] Returning to FIG. 4, at time t1 after a predetermined period has elapsed in period P1, since the torque command value τ* input to the switching unit 14 changes so as to increase, the switching unit 14 causes the driving unit 11 to switch the operation of the motor 20 to rectangular-wave voltage driving.

[0056] Here, the rectangular-wave voltage driving in the driving unit 11 will be described with reference to FIG. 7. FIG. 7 is a diagram schematically showing an example of the voltage waveforms of the U-phase AC voltage Vu, V-phase AC voltage Vv, and W-phase AC voltage Vw output from the driving unit 11 whose driving of the motor 20 has been switched to rectangular-wave voltage 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.

[0057] The rectangular-wave voltage drive unit 111 (see FIG. 1) that executes rectangular-wave voltage drive generates pulse signals Pau to Paz (see FIG. 1) input to the inverter unit 113 as pulse signals Pu to Pz. The pulse signals Pau to Paz are signals for causing the inverter unit 113 to output a U-phase AC voltage Vu, a V-phase AC voltage Vv, and a W-phase AC voltage Vw according to the excitation patterns of the U-phase winding 21u, the V-phase winding 21v, and the W-phase winding 21w corresponding to the rotation angle θ of the motor 20. In the rectangular-wave voltage drive, six semiconductor elements Qu to Qz provided in the inverter unit 113 are controlled for switching in the same manner as in vector control drive by the pulse signals Pau to Paz input from the rectangular-wave voltage drive unit 111 as the pulse signals Pu to Pz. 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, a constant 0V signal during the next 60° period, negative pulse signals during the next 120° period, and a constant 0V signal during the last 60° period in the period in which the electrical angle θe rotates 360°. The U-phase AC voltage Vu, the V-phase AC voltage Vv, and the W-phase AC voltage Vw are signals whose electrical angles θe are shifted from each other by 120°.

[0058] The pulse signals Pau to Paz generated by the rectangular-wave voltage drive unit 111 are also signals for causing the U-phase current Iu, the V-phase current Iv, and the W-phase current Iw input from the inverter unit 113 to 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, when the rectangular-wave voltage drive unit 111 causes the U-phase current Iu, the V-phase current Iv, and the W-phase current Iw to follow the q-axis current command value Iq * , the motor 20 operates so that the torque follows the torque command value τ * . By repeatedly operating the inverter unit 113 with such pulse signals Pau to Paz, 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 rotational speed ω and torque of the motor 20 approach desired values.

[0059] As shown in FIGS. 6 and 7, the Hall detection signals Hu, Hv, and Hw in the rectangular wave voltage drive have the same signal waveforms as the Hall detection signals Hu, Hv, and Hw in the vector control drive. Therefore, even when the motor 20 is driven by the rectangular wave voltage drive, the detection unit 12 can detect the rotational position (i.e., the rotation angle) of the rotor 23 in the same manner as in the case of the vector control drive.

[0060] Returning to FIG. 4, the period P2 from time t1 to the time t2 when the Hall detection signal Hu first rises 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, since the Hall detection signal Hu rises and the signal level changes, the switching unit 14 causes the drive unit 11 to end the operation of the motor 20 by the rectangular wave voltage drive.

[0061] In the period P3 after time t2, the motor control device 10 controls the motor 20 by switching the drive of the motor 20 between the rectangular wave voltage drive and the vector control drive according to the magnitude relationship between the rotational speed ω of the motor 20, the threshold value ωth, and the drive switching threshold value ωthc. That is, when the rotational 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". When the rotational 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".

[0062] When the motor 20 is driven by the vector control drive, when the torque command value τ * changes in a state where the rotational speed ω of the motor 20 becomes lower than the threshold value ωth, the motor 20 can be driven by the rectangular wave voltage drive (the flow from step S11 to step S14 shown in FIG. 3). Thereby, the motor control device 10 can perform the rectangular wave voltage By driving, the forced rotation of the motor 20 can be suppressed, preventing the motor 20 from locking. As a result, the motor control device 10 can control the motor 20 so that the rotational speed ω of the motor 20 follows the rotational speed corresponding to the change in the torque command value τ * Let's assume that a power control unit (not shown) provided in the vehicle 1 (see FIG. 1) and controlling the motor control device 10 recognizes the control of the motor 20 in a processing order such as "rapid deceleration → stop → acceleration". In this case, even if there is a deviation between the rotational speed (in other words, the number of rotations) of the motor 20 in the processing order recognized by the power control unit and the actual rotational speed of the motor 20, the motor control device 10 drives the motor 20 with a rectangular wave

[0063] in the period P2, thereby preventing the locking of the motor 20 and the poor rotation of the motor 20. Further, the motor control device 10 can control the motor 20 in a direction to reduce the deviation between the rotational speed in the processing order and the actual rotational speed by driving the motor 20 with a rectangular wave voltage in the period P2 voltage By driving the motor 20 with a rectangular wave drive in the period P2, the motor 20 can be controlled in a direction to reduce the deviation between the rotational speed in the processing order and the actual rotational speed

[0064] [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. Thereby, the motor control device 10 can reduce the processing load

[0065] In step S13 shown in FIG. 3, the switching unit 14 uses whether the torque command value τ * has changed as a criterion, but the change amount of the torque command value τ * may also be used as a criterion. As the change amount of the torque command value τ * , for example, the change rate of the torque command value τ * (that is, the time - differential value of the torque command value τ * ) may be used. Specifically, the switching unit 14 determines based on the torque command value τ *When the change amount of [[ID=]] is equal to or greater than a predetermined value (predetermined threshold value), the driving of the motor 20 may be switched from vector control driving to rectangular wave voltage driving (the flow from step S13 to step S14 shown in FIG. 3). Thereby, even if the torque command value τ * changes slightly due to misdetection of the hall detection signal Hu caused by 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. Therefore, the motor control device 10 can achieve the stabilization of the driving of the motor 20 at low speed.

[0066] In the process of step S15 shown in FIG. 3, the switching unit 14 uses the first change of the hall detection signal after starting the low-speed driving as the determination criterion, but it is not necessary to determine the change of the hall detection signal until a predetermined period has elapsed after starting the low-speed driving. Thereby, the motor control device 10 can surely secure the period for driving the motor 20 in the low-speed driving, so that the locking of the motor 20 and the rotation failure of the motor 20 can be prevented.

[0067] In the motor control device 10, the same hall detection signal is used for calculating the rotation speed ω of the motor 20 and detecting the change in the signal level in the low-speed driving, but different hall detection signals may be used.

[0068] [4. Configuration Supported by the Above Embodiment] The above embodiment is a specific example of the following configuration.

[0069] (Configuration 1) A drive unit capable of selectively driving a motor by applying a rectangular wave voltage to a stator winding provided in the motor for rectangular wave voltage drive to drive the motor, and applying a sine wave voltage to the stator winding for vector control drive to drive the motor; a command unit for commanding a torque command value for following the torque of the motor; and a switching unit for switching the drive of the motor by the drive unit between the rectangular wave voltage drive and the vector control drive. 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 at a rotational speed equal to or lower than a threshold value by the vector control drive. According to the motor control device of Configuration 1, even when the rotational speed of the motor suddenly decreases, the motor can be forced to rotate by performing rectangular wave voltage drive, and vibration of the motor can be suppressed. Thus, according to the motor control device of Configuration 1, stabilization of the motor output at low rotation can be achieved, and by extension, contribution to improvement of energy efficiency can be made.

[0070] (Configuration 2) After driving the motor by low-speed drive, which is the rectangular wave voltage drive switched based on the change in the torque command value, the switching unit ends the drive of the motor by the low-speed drive on the condition that the signal level of a position signal indicating the rotational position of a rotor provided in the motor has changed, and switches the drive of the motor between the rectangular wave voltage drive and the vector control drive according to the rotational speed at the time when the drive by the low-speed drive ends. The motor control device according to Configuration 1. According to the motor control device of Configuration 2, since an appropriate motor drive method is selected according to the rotational speed of the motor even after execution of low-speed drive, efficient drive can be performed even after rotating the motor again.

[0071] (Configuration 3) The switching unit switches the drive of the motor from the vector control drive to the rectangular wave voltage drive when the amount of change in the torque command value is equal to or greater than a predetermined value. The motor control device according to Configuration 1 or 2. According to the motor control device of Configuration 3, since a slight change in the torque command value due to misdetection of the position signal caused by noise or the like is not determined as a change in the torque command value, it is possible to stabilize the driving of the motor at low speeds.

[0072] (Configuration 4) The switching unit switches the driving of the motor from the vector control drive to the rectangular wave voltage drive when the torque command value changes from a value for decreasing or maintaining the torque at a constant value to a value for increasing the torque. The motor control device according to any one of Configurations 1 to 3. According to the motor control device of Configuration 4, when the motor rotates at a low speed, the rectangular wave voltage It is possible to suppress the motor from being locked by forcibly rotating the motor by driving.

[0073] (Configuration 5) A vehicle including 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 the rotational position of a rotor provided on the motor. According to the vehicle of Configuration 5, the same effects as those of the motor control devices of Configurations 1 to 4 can be obtained.

Description of Reference Numerals

[0074] 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 sensors, 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... Stages, Hu, Hv, Hw... Hall detection signals, 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 electrode side line, Lp... negative electrode side line, P1, P2, P3... periods, Pau~Paz, Pbu~Pbz, Pu~Pz... pulse signals, Qu~Qz... semiconductor elements, Scd1, Scd2... drive switching signals, 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

A drive unit (11) capable of selectively driving a motor (20) by applying a rectangular wave voltage to stator windings (21u, 21v, 21w) provided in the motor (20) for rectangular wave voltage drive and applying a sine wave voltage to the stator windings (21u, 21v, 21w) for vector control drive to drive the motor (20), A command unit (15) that outputs a torque command value (τ*) for instructing the torque of the motor (20), A switching unit (14) that causes the drive unit (11) to switch the drive of the motor (20) between the rectangular wave voltage drive and the vector control drive, Comprising, The switching unit (14) is, When the motor (20) is being controlled by the vector control drive, after the rotational speed (ω) of the motor becomes equal to or lower than a threshold value (ωth), if the torque command value (τ*) input from the command unit (15) changes to a value indicating an increase in torque, the drive of the motor (20) is switched from the vector control drive to the rectangular wave voltage drive, Based on the change in the torque command value (τ ＊ ), after driving the motor (20) by the low-speed drive which is the rectangular wave voltage drive switched according to the change, on the condition that the signal level of the position signal indicating the rotational position of the rotor (23) provided in the motor (20) has changed, end the drive of the motor (20) by the low-speed drive, and according to the rotational speed (ω) at the time when the low-speed drive is ended, switch the drive of the motor (20) to the rectangular wave voltage drive or the vector control drive. A motor control device (10). A drive unit (11) capable of selectively driving a motor (20) by applying a rectangular wave voltage to stator windings (21u, 21v, 21w) provided in the motor (20) for rectangular wave voltage drive and applying a sine wave voltage to the stator windings (21u, 21v, 21w) for vector control drive to drive the motor (20), A command unit (15) that outputs a torque command value (τ*) for instructing the torque of the motor (20), A switching unit (14) that causes the drive unit (11) to switch the drive of the motor (20) between the rectangular wave voltage drive and the vector control drive, Comprising, The switching unit (14) is, When the motor (20) is being controlled by the vector control drive, after the rotational speed (ω) of the motor becomes equal to or lower than a threshold value (ωth), if the torque command value (τ*) input from the command unit (15) changes to a value indicating an increase in torque, the drive of the motor (20) is switched from the vector control drive to the rectangular wave voltage drive, The torque command value (τ ＊ ) when the torque increase amount indicated in the change is equal to or greater than a predetermined value, causes the drive of the motor (20) to be switched from the vector control drive to the rectangular wave voltage drive. A motor control device (10).

3. The change in the torque command value (τ ＊ ) is a change from a value that decreases torque or maintains it at a constant value to a value for increasing torque. The motor control device (10) according to claim 1. The change in the torque command value (τ*) is a change from a value for decreasing torque or maintaining a constant value to a value for increasing torque. The motor control device (10) according to claim 2.

5. The 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 a position signal (Hu, Hv, Hw) indicating the rotational position of a rotor (23) provided on the motor (20), and a vehicle comprising the same.

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