Electric motor control device

Abstract

Disclosed is an electric motor control device capable of raising the temperature of a battery and consuming regenerative power without an increase in device size. This electric motor control device (200) comprises: a d-axis current command generation unit (201) that controls an electric motor (10) using a power conversion device (20) and generates a d-axis current command on the basis of a torque command for the electric motor; and a loss generation control d-axis current command generation unit (205) that, on the basis of a current amplitude command and the torque command, generates a loss generation control d-axis current command for executing loss generation control for increasing the power loss of the electric motor, wherein the d-axis current command is corrected on the basis of the loss generation control d-axis current command.

Description

Control device for electric motors

[0001] The present invention relates to a control device for an electric motor that drives and controls the electric motor using a power conversion device.

[0002] AC motors, such as synchronous motors, are driven and controlled by power conversion devices that convert DC power to AC power in various fields such as industrial machinery, electric vehicles, and home appliances.

[0003] In electric vehicles and the like, a battery is installed, and DC power is supplied by the battery to a power converter. For example, in the motor drive device described in Patent Document 1, an inverter is connected to a permanent magnet synchronous motor. The inverter receives the power supply voltage output from a high-voltage battery. The inverter is PWM controlled by a motor control device.

[0004] International Publication No. 2023 / 175832

[0005] Battery performance varies with temperature. As the temperature drops, the power output decreases. This reduces the inverter's output power. Also, when the battery is nearly fully charged, it becomes more difficult to recharge it with regenerative power. This limits the regenerative torque.

[0006] It is possible to raise the battery temperature using heating devices such as heaters, or to consume regenerative power using regenerative resistors. However, this increases the number of components, resulting in a larger motor drive unit.

[0007] Therefore, the present invention provides a control device for an electric motor that can raise the temperature of the battery and consume regenerative power without increasing the size of the device.

[0008] To solve the above problems, the electric motor control device according to the present invention controls the electric motor using a power converter, and comprises a d-axis current command generation unit that generates a d-axis current command based on the torque command of the electric motor, and a loss generation control d-axis current command generation unit that generates a loss generation control d-axis current command for performing loss generation control that increases the power loss of the electric motor based on the current amplitude command and the torque command, wherein the d-axis current command is corrected based on the loss generation control d-axis current command.

[0009] According to the present invention, an electric motor and a power converter can be used instead of a heating device and a power consumption device. This makes it possible to raise the temperature of the battery or consume regenerative power without increasing the size of the device.

[0010] Other issues, configurations, and effects not mentioned above will be clarified by the following description of the embodiments.

[0011] This is a circuit diagram and functional block diagram showing the configuration of an electric motor drive system according to one embodiment. This is an operation state diagram showing an example of the operation of the control device 200. This is a functional block diagram showing the configuration of the flux weakening control unit 206 for loss generation control. This is a time chart showing an example of the loss generation control operation of the control device 200. This is a circuit diagram and functional block diagram showing the configuration of an electric motor drive system according to one modification.

[0012] Embodiments of the present invention will be described below with reference to the drawings. In each figure, elements with the same reference number represent the same or similar functional elements.

[0013] Figure 1 shows a circuit diagram and a functional block diagram illustrating the configuration of an electric motor drive system, which is one embodiment of the present invention.

[0014] As shown in Figure 1, in this embodiment, the inverter circuit 20 and the battery 40, which serves as a DC power source, are connected to each other via a smoothing capacitor 30. The inverter circuit 20 constitutes the main circuit of a so-called voltage-type inverter. A secondary battery such as a lithium-ion battery or a nickel-metal hydride battery is used as the battery 40.

[0015] In this embodiment, the DC power from the battery 40 is converted into three-phase AC power by the inverter circuit 20, and the permanent magnet synchronous motor (hereinafter referred to as "PM motor") 10 is rotated by the three-phase AC power output by the inverter circuit 20.

[0016] The inverter circuit 20 is equipped with six semiconductor switching elements (insulated-gate bipolar transistors (IGBTs) in Figure 1), which are connected in series in pairs to form three upper and lower arms (U-phase, V-phase, and W-phase). Each series connection point of the three upper and lower arms is electrically connected to the three-phase AC terminals of the PM motor 10. Both ends of the upper and lower arms are electrically connected to the battery 40. A diode is electrically connected in antiparallel to each semiconductor switching element (between the collector and emitter of the IGBT in Figure 1). This diode operates as a so-called freewheeling diode.

[0017] In the inverter circuit 20, the DC power input from the battery 40 is converted into three-phase AC power by the switching operation of the semiconductor switching element, and this three-phase AC power is output to the PM motor 10 from the series connection point of the upper and lower arms. The smoothing capacitor 30 suppresses fluctuations in the input voltage due to the switching operation and stabilizes the operation of the inverter circuit 20.

[0018] The control device 200 controls the torque and speed of the PM motor 10 by outputting control signals (gate signals) to the control terminals of each semiconductor switching element in the inverter circuit 20 (in Figure 1, the gate terminals of the IGBTs), thereby controlling the current supplied to the PM motor 10. In this embodiment, the control device 200 controls the three-phase AC current values ​​iu, iv, i detected by the current sensor 70. ｗ Based on i ｕ i ｖ i ｗ The desired torque (T ＊ Each semiconductor switching element is controlled to approach the current command required to obtain the desired result.

[0019] In addition, in FIG. 1, for simplicity, a current sensor for detecting a three-phase alternating current is represented by a single current sensor 70. Also, of the three-phase alternating current values, two phases may be detected and the other one phase may be calculated.

[0020] Further, when the control device 200 receives a current amplitude command I ＊ that serves as a loss generation command, based on the current amplitude command I ＊ and the torque command T ＊ while holding the torque generated by the PM motor 10 at T ＊ the control device controls each semiconductor switching element so that a current having an amplitude I ＊ larger than normal flows through the PM motor 10, increasing the power loss generated by the PM motor 10 and the semiconductor switching elements. As a result, the battery 40 can be warmed by the heat generated by the PM motor 10 and the semiconductor switching elements, or regenerative power can be consumed by the PM motor 10 and the semiconductor switching elements.

[0021] As shown in FIG. 1, the control device 200 includes an MTPA control unit 201, an i ｑ ＊ (q-axis current command) generation unit 202, a field weakening control unit 203 (for normal control), a voltage amplitude calculation unit 204, a Δi ｄ ＊ (d-axis current command offset) generation unit 205, a field weakening control unit 206 (for loss generation control), a current amplitude compensation unit 207, a current amplitude calculation unit 208, a current control unit 220, a coordinate conversion unit 221, a rotation position detection unit 222, a coordinate conversion unit 223, and a PWM control unit 224.

[0022] The control device 200 includes a computer system such as a microcomputer, and operates as each unit when the computer system executes a predetermined program.

[0023] The rotation position detection unit 222 calculates a rotor angle θ based on a rotation detection signal S ｒ from the rotation detector 90. Note that θ represents the phase of the d-axis in the rotating coordinate system.

[0024] The coordinate conversion unit 223 uses θ from the rotation position detection unit 222 to perform i ｕ , iｖ i ｗ The d-axis current detection value i in the rotating coordinates ｄ and q-axis current detection value i ｑ Convert to.

[0025] The MTPA control unit 201 receives a torque command T from a higher-level control unit (not shown). ＊ Based on this, the desired torque (T) is achieved through so-called maximum torque / current control. ＊ ) d-axis current command i ｄＭＴＰＡ ＊ The MTPA control unit 201 uses map data or a function representing the relationship between the maximum torque and the current vector in the rotation coordinates to calculate T ＊ i is the d-axis component of the current vector that gives the maximum torque. ｄＭＴＰＡ ＊ Calculate (<0).

[0026] i ｑ ＊ The generating unit 202 is T ＊ The d-axis current command i is input to the current control unit 220, which will be described later. ｄ ＊ Based on this, the desired torque (T ＊ The q-axis current command to obtain ) is calculated. In this embodiment, i ｑ ＊ The generation unit 202 corrects the calculated value of the q-axis current command according to the motor temperature Temp, and generates the corrected q-axis current command i ｑ ＊ Outputs.

[0027] When the temperature of the permanent magnets in the PM motor 10 rises, the magnetic flux of the magnets decreases, so the torque generated by the PM motor 10 will be T if the calculated value is used. ＊ It becomes smaller than i. ｑ ＊ The generation unit 202 multiplies the calculated value by a correction coefficient K (>1) i ｑ ＊ This compensates for the decrease in torque caused by the reduction in magnetic flux.

[0028] i ｑ ＊The generation unit 202 corrects the calculated value of the q-axis current command by using map data or a function that represents the relationship between Temp and K, and by using K corresponding to Temp.

[0029] Temp is detected by the temperature sensor 100. For example, a thermistor is used as the temperature sensor 100. The temperature sensor 100 is installed, for example, at the coil end of the stator of the PM motor 10. Note that the value of the temperature sensor 100 and i ｕ i ｖ i ｗ Based on this, the magnet temperature may be estimated using an estimator that employs a thermal circuit network or the like (not shown in the diagram), and this can be set as Temp.

[0030] In normal control, the weakening flux control unit 203, when the modulation rate exceeds a predetermined value (target modulation rate value for normal control), will use the i calculated by the MTPA control unit 201. ｄＭＴＰＡ ＊ Correction amount δi for (<0) ｄＦＷ Calculate (<0). δi ｄＦＷ The adder 210b performs i ｄＭＴＰＡ ＊ This is added to the d-axis current. As a result, the range of rotational speeds (rotational velocity) over which the PM motor 10 can operate with a constant torque is widened by the flux weakening effect caused by the d-axis magnetic flux generated by the d-axis current, that is, the effect of weakening the field magnetic flux (magnetic flux).

[0031] The flux weakening control unit 203 receives the dq axis current command (v) from the voltage amplitude calculation unit 204. ｄ ＊ ,v ｑ ＊ The voltage amplitude V(=(v)) calculated from ) ｄ ＊ ) ２ + (v ｑ ＊ ) ２ ) １／２ ) and DC power supply voltage V ＤＣ Based on this, the modulation rate M (= V / V) ＤＣ The device calculates the magnetic flux weakening control unit 203. The device compares the calculated M with a predetermined value (the target modulation rate value for normal control) and determines whether the modulation rate exceeds the predetermined value.

[0032] δi ｄＦＷis generated by feedback control so that the modulation rate M does not exceed the target value for normal control. Note that the torque command T ＊ and V ＤＣ δi may be generated by feedforward control using map data or a function based on the rotor angular velocity calculated by differentiating the rotor angle θ, etc. Alternatively, it may be generated by a combination of these feedback control and feedforward control. ｄＦＷ

[0033] Note that V ＤＣ is detected by the voltage detector 80 at both ends of the smoothing capacitor 30.

[0034] Δi ｄ ＊ The (d-axis current command offset) generation unit 205, in the case of loss generation control, while holding the torque generated by the PM motor 10 at T ＊ and the current amplitude command I from the upper-level control device ＊ calculates a correction amount (offset amount) Δi ＊ such that the power losses generated by the PM motor 10 and the semiconductor switching elements increase. Note that, as described above, I ｄＭＴＰＡ ＊ (<0) and Δi ｄ ＊ (>0). Note that, as described above, I ＊ is larger than the current amplitude in the case of normal control.

[0035] The field weakening control unit 206, in the case of loss generation control, if the modulation rate exceeds a predetermined value (loss control modulation rate target value), calculates a correction amount δi ｄ ＊ such that δi ｄ ＊ (>0) of the correction amount Δi ｄｌｏｓｓ (<0) calculated by the generation unit 205. δi ｄloss is added to Δi ｄ ＊ by the adder 210d. As a result, in the case of loss generation control, when the modulation rate increases, Δi ｄ ＊ ​The d-axis magnetic flux strengthened according to this can be weakened. Thereby, in the case of loss generation control, the PM motor 10 can be stably driven and controlled.

[0036] Similar to the field weakening control unit 203, the field weakening control unit 206 calculates a modulation ratio M (=V / V ＤＣ ) based on the voltage amplitude V calculated by the voltage amplitude calculation unit 204 and the DC power supply voltage V ＤＣ ). The field weakening control unit 206 compares the calculated M with a predetermined value (modulation ratio target value for loss control) and determines whether the modulation ratio exceeds the predetermined value. δi ｄloss is generated by feedback control so that the modulation ratio M does not exceed the normal control target value.

[0037] Incidentally, as will be described later, for the modulation ratio, the normal control target value is larger than the loss generation control target value. Also, δi ｄｌｏｓｓ (<0) is limited to the range of -Δi ｄ ＊ <δi ｄｌｏｓｓ <0. For this reason, the field weakening control unit 203 (for normal control) and the field weakening control unit 206 (for loss generation control) are prevented from operating simultaneously and interfering with each other.

[0038] The Δi ｄｌｏｓｓ corrected by δi ｄ ＊ , that is, the addition value by the adder 210d, is added to i ｄＭＴＰＡ ＊ by the adder 210a.

[0039] In the case of loss generation control, the current amplitude compensation unit 207 calculates a correction amount δi ＊ of the d-axis current command by, for example, PI control so that the amplitude I of the current flowing through the PM motor 10 matches the current amplitude command I ｄ ＊ . δi ｄ ＊ is added to the Δi ｄ ＊ calculated by the Δi ｄ ＊ generation unit 205 by the adder 210c.

[0040] I is the dq axis current command (i) input to the current control unit 220. ｄ ＊ i ｑ ＊ Based on this, the current amplitude calculation unit 208 calculates (I = ((i ｄ ＊ ) ２ + (i ｑ ＊ ) ２ ) １／２ ).

[0041] In loss control, when the temperature of the permanent magnets in the PM motor 10 increases, the magnetic flux of the magnets decreases, causing the amplitudes I and I of the current flowing through the PM motor 10 to change. ＊ A deviation may occur between these two. In this embodiment, however, the current amplitude compensation unit 207 compensates for the deviation of I from I*.

[0042] The current control unit 220 receives the current detection value i from the coordinate transformation unit 223. ｄ and i ｑ However, the current command i ｄ ＊ and i ｑ ＊ The d-axis voltage command v in the rotation coordinates is set to match this. ｄ ＊ and q-axis voltage command v ｑ ＊ Generates.

[0043] In this embodiment, the current control unit 220 uses a voltage equation (inverse model) that expresses the dq-axis voltage applied to the PM motor 10 as the dq-axis current flowing through the PM motor 10, v ｄ ＊ and v ｑ ＊ This generates the dq-axis current in this voltage equation, i ｄ ＊ and i ｑ ＊ (Hereinafter referred to as "the first dq axis current command") and the detected dq axis current i ｄ and i ｑ The second dq-axis current command i is calculated based on the above. ｄ ＊＊ and i ｑ ＊＊Let's assume that.

[0044] The current control unit 220 uses a PI controller to detect the d-axis current i ｄ The first d-axis current command i ｄ ＊ The second d-axis current command i is set to match ｄ ＊＊ The current control unit 220 uses a PI controller to calculate the q-axis current detection value i. ｑ The first q-axis current command i ｑ ＊ The second q-axis current command i is set to match ｑ ＊＊ Calculate.

[0045] The coordinate transformation unit 221 uses θ from the rotation position detection unit 222 to determine v ｄ ＊ ,v ｑ ＊ The three-phase voltage command v ｕ ＊ ,v ｖ ＊ ,v ｗ ＊ Convert to.

[0046] The PWM control unit 224 is v ｕ ＊ ,v ｖ ＊ ,v ｗ ＊ Accordingly, for example, a PWM control signal S is applied to the control terminals of each semiconductor switching element in the inverter circuit 20 (in Figure 1, the gate terminal of the IGBT) by carrier comparison type PWM control. Ｇ Generates a gate signal.

[0047] Figure 2 is an operation diagram showing an example of the operation of the control device 200.

[0048] Points A and A' in Figure 2 are the operating points (i) of the current control operation by the control device 200 in the case of normal control. ｄ ＊ i ｑ ＊ ) indicates.

[0049] Point A is the torque command T ＊This is the intersection point of the constant torque curve and the MTPA (maximum torque / current) curve for i at point A. ｄ ＊ However, the d-axis current command i calculated by the MTPA control unit 201 (Figure 1) ｄＭＴＰＡ ＊ This corresponds to the MTPA control unit 201 (Figure 1) i ｄＭＴＰＡ ＊ The aforementioned map data or function used in the calculation represents the MTPA (Maximum Torque / Current) curve.

[0050] When the flux weakening control unit 203 for normal control is activated, the operating point is on the constant torque curve, i ｄ ＊ Move from point A to point A' in the negative direction of . ｄ ＊ And, i at point A ｄ ＊ The difference is calculated by the weakening flux control unit 203, i ｄＭＴＰＡ ＊ Correction amount δi ｄＦＷ It corresponds to this.

[0051] Points B and B' in Figure 2 are the operating points (i) of the current control operation by the control device 200 in the case of loss generation control. ｄ ＊ i ｑ ＊ ) indicates.

[0052] When transitioning from normal control to loss-generating control, Δi ｄ ＊ When the generating unit 205 (Figure 1) operates, the operating point is on the constant torque curve, i ｄ ＊ Move from point A to point B in the positive direction of . ｄ ＊ And, i at point A ｄ ＊ The difference is Δi ｄ ＊ i, calculated by the generation unit 205 ｄＭＴＰＡ ＊ Correction amount Δi ｄ ＊ It corresponds to this.

[0053] As shown in Figure 2, point B is the current amplitude command I which is the command for generating a loss.＊ A constant current curve with amplitude T, and a torque command T ＊ It is the intersection point with the constant torque curve and is not located on the MTPA curve. Therefore, when point B is the operating point, the torque generated by the PM motor 10 is T ＊ Although it is held in place, the efficiency of the PM motor 10 decreases. Therefore, the power loss of the PM motor 10 can be increased.

[0054] When the flux weakening control unit 206 for loss generation control operates, the operating point is on the constant torque curve, i ｄ ＊ Move from point B to point B' in the negative direction of . ｄ ＊ And, i at point B ｄ ＊ The difference is calculated by the flux weakening control unit 206, Δi ｄ ＊ Correction amount δi ｄｌｏｓｓ This corresponds to δi. ｄｌｏｓｓ is, -δi ｄｌｏｓｓ < δi ｄｌｏｓｓ The range is limited to <0. This allows for a flux weakening effect to be obtained while maintaining an effective level of power loss in the PM motor 10.

[0055] Figure 3 is a functional block diagram showing the configuration of the flux weakening control unit 206 for loss generation control.

[0056] The flux weakening control unit 206 includes a proportional control unit 206a, an adder / subtractor 206b, an integrator 206c, a correction amount generation unit 206d, a proportional control unit 206e, and a control operation determination unit 206f.

[0057] The proportional control unit 206a controls the DC power supply voltage V ＤＣ to K Ｍｆ Double.

[0058] Output values ​​(K) of adder / subtractor 206b and proportionalizer 206a Ｍｆ ・V ＤＣ Subtract the voltage amplitude V from ).

[0059] The integrator 206c adds an integral gain K to the output value of the adder / subtractor 206b. Ｉ K Ｉ ・(K Ｍｆ ・VＤＣ Integrate (-V).

[0060] Naozaki K Ｍｆ The value of is set according to the target modulation rate value for loss control. Also, K Ｉ This is set appropriately according to the desired degree (speed) of increase or decrease of the integral value by the integrator 206c. For example, K Ｉ By accelerating the increase or decrease of the integral value according to the value of i, ｄ ＊ This allows for a rapid reduction from a positive value (operating point B in Figure 2) to a negative value, thereby obtaining an effective flux weakening effect, and also allows for a rapid return from a negative value to a positive value. Typically, it is preferable to set the response to be approximately 5 to 10 times slower than the response of the current control unit 220.

[0061] The correction amount generation unit 206d generates a correction amount δi according to the integral value output by the integrator 206c. ｄｌｏｓｓ The correction amount generation unit 206d is equipped with a limiter, and generates δi. ｄｌｏｓｓ The value is limited to a predetermined upper and lower limit.

[0062] The proportional device 206e has Δi ｄ ＊ The generation unit 205 calculates Δi ｄ ＊ The value obtained by multiplying by -1 (-Δi ｄ ＊ ) in the correction amount generation unit 206d, δi ｄｌｏｓｓ Set to the lower limit. ｄｌｏｓｓ Zero is set as the upper limit.

[0063] The control operation determination unit 206f generates a control signal S to operate or stop the integrator 206c according to the modulation rate. The control operation determination unit 206f ＤＣ Based on V, the modulation rate M (= V / V) ＤＣ The control operation determination unit 206f calculates the modulation rate. The control operation determination unit 206f compares the calculated modulation rate with a predetermined target value and outputs a command signal S to the integrator to either start operation or stop operation according to the comparison result. The control operation determination unit 206f controls the operation of the integrator 206c according to the command signal S.

[0064] Figure 4 is a time chart showing an example of the loss generation control operation of the control device 200.

[0065] The operation of the control operation determination unit 206f (Figure 3) in the flux weakening control unit 206 for loss generation control will be explained below using Figure 4.

[0066] The control operation determination unit 206f determines that when loss generation control is being performed (FL = ON (1)), the modulation rate M increases, and the target value M for flux weakening control (loss generation) is set. １ Exceeded (M > M) １ ) If it is determined that (time t １ ), the integrator 206c is activated to operate the flux weakening control unit 206.

[0067] The control operation determination unit 206f determines that if the modulation rate M increases, the target value M for stopping loss generation control will be set. ３ (M １ < M ３ ) exceeds (M > M ３ If it is determined that this is the case, the integrator 206c is stopped and the flux weakening control unit 206 is stopped (at time t ２ ). Furthermore, as indicated by the loss generation control operation flag FL, at time t ２ In this state, the control device 200 stops the execution of loss generation control.

[0068] The control operation determination unit 206f determines that the modulation rate M decreases and sets the target value M for stopping loss generation control. ２ (M １ < M ２ < M ３ ) fell below (M < M ２ If it is determined that ), the stop of the integrator 206c is released and the integrator 206c is activated, and the flux weakening control unit 206 is activated (at time t ３ ). Furthermore, as indicated by the loss generation control operation flag FL, at time t ２ ~t ３ At this point, the control device 200 has suspended the execution of the loss generation control. Furthermore, at time t ３ In this state, the control device 200 resumes the execution of loss generation control.

[0069] The control operation determination unit 206f determines that the modulation rate M decreases and sets the target value M for stopping loss generation control. ２ (M１ < M ２ < M ３ ) fell below (M < M ２ If it is determined that ), the integrator 206c is activated to activate the flux weakening control unit 206 (at time t ３ ). Note that time t ２ ~t ３ In this case, as indicated by the loss generation control operation flag FL (FL = OFF (0)), the control device 200 has suspended the execution of loss generation control. Furthermore, at time t ３ In this state, the control device 200 resumes the execution of loss generation control.

[0070] The control operation determination unit 206f determines that, after the restart of loss generation control, the modulation rate M decreases, and the target value M for flux weakening control (loss generation) is set. １ It fell below (M < M １ ) If it is determined that (time t ４ ), the integrator 206c is stopped, and the flux weakening control unit 206 is stopped.

[0071] As shown in Figure 4, the operation of the flux weakening control unit 206 for loss generation control is related to M １ , M ２ , M ３ In all cases, the target value M for flux weakening control in the flux weakening control unit 203 for normal control. ４ The size is different from M ４ It is smaller than this. Therefore, interference between the flux weakening control unit 203 and the flux weakening control unit 206 is prevented.

[0072] As mentioned above, M ２ < M ３ In other words, hysteresis is set in the determination results of stopping and releasing the operation of the integrator 206c in the control operation determination unit 206f. This prevents chattering of the determination results.

[0073] Figure 5 shows a circuit diagram and functional block diagram illustrating the configuration of an electric motor drive system, which is a modified example of the embodiment shown in Figure 1. The differences from the embodiment in Figure 1 will be explained below.

[0074] In this modified example, δi ｄlossInstead of feedback control using modulation rate for generation, feedforward control is used. δi ｄloss The generating unit 301 generates the torque command T ＊ and V ＤＣ Based on the rotor angular velocity ω calculated by the velocity calculation unit 302, δi is used with map data or a function. ｄloss Generates δi ｄloss This is input to the minimum value calculation unit 303 (min: outputs the minimum value among the inputs). The minimum value calculation unit 303 takes the output of the adder 210c and δi ｄloss Output the smaller of the two.

[0075] In this configuration, the feedback control for flux weakening control in the control device 200 is normally handled by only one flux weakening control unit 203. Therefore, the flux weakening control unit 203 (for normal control) and the flux weakening control unit 206 (for loss generation control) do not interfere with each other, eliminating the need to design an on / off threshold for the flux weakening control unit 206 according to the modulation rate. Furthermore, since the target modulation rate for loss control can be the same as that of the normal flux weakening control unit 203, the operating range of loss control can be expanded to a higher modulation rate range.

[0076] According to the above embodiment, the control device 200 controls the torque command (T) of the electric motor (PM motor 10). ＊ Based on this, the d-axis current command (i ｄＭＴＰＡ ＊ A d-axis current command generation unit (MTPA control unit 201) that generates a current amplitude command (I ＊ ) and torque command (T ＊ Based on this, a d-axis current command (Δi) for loss generation control is used to perform loss generation control that increases the power loss of the electric motor (PM motor 10). ｄ ＊ Loss generation control d-axis current command generation unit (Δi ｄ ＊ The generation unit 205) and the d-axis current command (i ｄＭＴＰＡ ＊ ) is a d-axis current command for loss generation control (Δi ｄ ＊ It will be corrected based on the following.

[0077] This increases the power loss of the electric motor (PM motor 10), allowing the battery to be warmed or regenerated power to be consumed without adding a heating device or regenerative resistor. Furthermore, according to this embodiment, the power loss of the electric motor (PM motor 10) can be increased while maintaining the torque generated by the electric motor (PM motor 10).

[0078] Furthermore, the control device 200 according to this embodiment can also be applied when a power converter that receives DC power from a DC power source other than the battery 40 is used. In this case as well, the electric motor can be used as a heat generating device or a power consuming device.

[0079] It should be noted that the present invention is not limited to the embodiments described above, and various modifications are included. For example, the embodiments described above are described in detail for the purpose of clearly illustrating the present invention, and are not necessarily limited to those having all the configurations described. Furthermore, it is possible to add, delete, or replace some of the configurations of the embodiments with other configurations.

[0080] For example, the control lines and signal lines shown in the diagram are those deemed necessary for explanation and do not necessarily represent all control lines and signal lines required for implementing the present invention.

[0081] The control device 200 is not limited to a microcomputer; it may also be configured using an FPGA or the like.

[0082] The semiconductor switching elements that make up the inverter circuit are not limited to IGBTs; power MOSFETs and other types may also be used.

[0083] 10: PM motor, 20: Inverter circuit, 30: Smoothing capacitor, 40: Battery, 70: Current sensor, 80: Voltage detector, 90: Rotation detector, 100: Temperature detector, 200: Control device, 201: MTPA control unit, 202: i ｑ ＊ Generation unit, 203: Magnetic flux weakening control unit (for normal control), 204: Voltage amplitude calculation unit, 205: Δi ｄ ＊206: Generation unit, 206: Magnetic flux weakening control unit (for loss generation control), 206a: Comparator, 206b: Adder / subtractor, 206c: Integrator, 206d: Correction amount generation unit, 206e: Proportional unit, 206f: Control operation determination unit, 207: Current amplitude compensation unit, 208: Current amplitude calculation unit, 210a, 210b, 210c, 210d: Adder, 220: Current control unit, 221: Coordinate transformation unit, 222: Rotation position detection unit, 223: Coordinate transformation unit, 224: PWM control unit, 301: δi ｄloss Generation unit, 302: Speed ​​calculation unit, 303: Minimum value calculation unit

Claims

1. A control device for an electric motor that controls an electric motor using a power converter, comprising: a d-axis current command generation unit that generates a d-axis current command based on a torque command of the electric motor; and a loss generation control d-axis current command generation unit that generates a loss generation control d-axis current command for performing loss generation control to increase the power loss of the electric motor based on a current amplitude command and the torque command, wherein the d-axis current command is corrected based on the loss generation control d-axis current command.

2. A control device for an electric motor according to claim 1, wherein the d-axis current command generation unit for loss generation control generates the d-axis current command for loss generation control so that the electric motor generates torque corresponding to the torque command.

3. A control device for an electric motor according to claim 1, further comprising: a flux weakening control unit that performs flux weakening control to correct the d-axis current command to weaken the field flux of the electric motor; and a flux weakening control unit for loss generation control that corrects the d-axis current command for loss generation control when performing flux weakening control while loss generation control is being executed.

4. A motor control device according to claim 3, characterized in that the flux weakening control unit and the flux weakening control unit for loss generation control operate according to the modulation rate, and the modulation rate at which the flux weakening control unit operates is greater than the modulation rate at which the flux weakening control unit for loss generation control operates.

5. A motor control device according to claim 3, characterized in that the magnitude of the correction amount for the d-axis current command for loss generation control by the flux weakening control unit for loss generation control is limited to between zero and the magnitude of the d-axis current command for loss generation control.

6. A control device for an electric motor according to claim 1, further comprising a current amplitude compensation unit that compensates the current amplitude command based on a q-axis current command.

7. A motor control device according to claim 6, characterized in that the q-axis current command is corrected according to the temperature of the motor.

Images