Motor control device

Abstract

To provide a control device capable of quickly terminating warming-up of a winding field type electric motor.SOLUTION: An electric motor control device comprises: a temperature acquisition device that acquires a stator temperature and a rotor temperature of a winding field type electric motor; an inverter; and a controller that controls the inverter. The controller sets a q-axis stator current command value corresponding to a torque component to zero, calculates a warming-up stator current command value that a d-axis stator current command value corresponding to an excitation component varies alternately to a positive side and a negative side in a first cycle, and a warming-up rotor current command value that an upper limit value and a lower limit value alternately vary in a second cycle, executes warming-up operation using at least the warming-up stator current command value in a case where the stator temperature is lower than a stator temperature threshold for determining the necessity of warming-up, and executes warming-up operation using at least the warming-up rotor current command value in a case where the rotor temperature is lower than a rotor temperature threshold for determining the necessity of warming-up.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to an electric motor control device for controlling a wound field type electric motor for vehicle drive.

Background Art

[0002] Regarding electric vehicles, there is a problem that at low temperatures, the efficiency of the electric motor decreases due to an increase in friction such as the cooling oil of the electric motor, the reduction gear, and the bearings, leading to a decrease in power consumption performance. As a countermeasure, it is known to warm up the electric motor by setting the current of the component (q-axis component) contributing to torque to zero and passing the current of the component (d-axis component) not contributing to torque during parking, and using the heat generated by the energization to warm up the electric motor. However, in order to increase the warm-up speed, it is necessary to increase the current value. Therefore, in the case of a permanent magnet type electric motor, there is a problem that the permanent magnet is demagnetized by the magnetic flux in the weakening direction generated by passing the current.

[0003] Patent Document 1 discloses control for promoting warm-up while preventing demagnetization. Specifically, the d-axis current with a current advance angle of 90° and the d-axis current with a current advance angle of 270° are alternately passed at a predetermined cycle. Then, the current value of the d-axis current with a current advance angle of 270° that generates a magnetic flux in the strengthening direction is made larger than the current value of the d-axis current with a current advance angle of 90° that generates a magnetic flux in the weakening direction, or the energization time of the d-axis current with a current advance angle of 270° is made longer than the energization time of the d-axis current with a current advance angle of 90°.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, if the d-axis current with a current advance angle of 90° is made smaller than the d-axis current with a current advance angle of 270°, the copper loss decreases by the amount of the reduction. Also, if the energization time of the d-axis current with a current advance angle of 90° is made longer than the energization time of the d-axis current with a current advance angle of 270°, the iron loss decreases by the amount of the increase. That is, in the control described in the above literature, there is a problem that the time required for warm-up becomes longer due to the reduction in loss, the desired temperature cannot be reached, and more power is consumed.

[0006] Therefore, in view of the above problems, an object of the present invention is to provide a control device capable of efficiently performing warm-up of an electric motor.

Means for Solving the Problems

[0007] According to an aspect of the present invention, there is provided an electric motor control device that controls a wound field type electric motor for vehicle drive. The control device includes a temperature acquisition device that directly or indirectly acquires the stator temperature and the rotor temperature of the wound field type electric motor, an inverter that converts and supplies power to the wound field type electric motor, and a control unit that calculates a stator current command value and a rotor current command value of the wound field type electric motor and controls the inverter based on each current command value. The control unit has a stator current command value of the q-axis, which is the axis corresponding to the torque component of the wound field type electric motor, being zero, and a stator current command value of the d-axis, which is the axis corresponding to the excitation component of the wound field type electric motor, changing alternately in a first cycle between the positive side, which is the strengthening direction with respect to the rotor field direction, and the negative side, which is the weakening direction, as a warm-up stator current command value, and a warm-up rotor current command value in which the upper limit value and the lower limit value change alternately in a second cycle. When the stator temperature is lower than a stator temperature threshold value for determining the necessity of warm-up, warm-up is performed using at least the warm-up stator current command value, and when the rotor temperature is lower than a rotor temperature threshold value for determining the necessity of warm-up, warm-up is performed using at least the warm-up rotor current command value. When the stator temperature is lower than the stator temperature threshold for determining the necessity of warm-up and the rotor temperature is lower than the rotor temperature threshold for determining the necessity of warm-up, the first period of the stator current command value for warm-up is made to coincide with the second period of the rotor current command value for warm-up, and the timing when the d-axis stator current command value becomes positive is made to coincide with the timing when the rotor current command value for warm-up becomes the upper limit value, and the timing when the d-axis stator current command value becomes negative is made to coincide with the timing when the rotor current command value for warm-up becomes the lower limit value, respectively.

Effects of the Invention

[0008] According to the above aspect, it is possible to provide a control device capable of efficiently performing warm-up of an electric motor.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a block diagram showing the configuration of a vehicle system equipped with an electric motor control device according to the present embodiment. Hereinafter, an example in which the electric motor control device of this example is applied to an electric vehicle will be described. However, the electric motor control device of this example can also be applied to vehicles other than electric vehicles such as hybrid electric vehicles (HEV).

[0011] As shown in FIG. 1, a vehicle including the electric motor control device of this example includes a battery 1, an inverter 2, a drive motor 3, a speed reducer 4, a drive shaft 5, drive wheels 6, 7, a voltage sensor 8, a current sensor 9, a rotation sensor 10, a temperature sensor 11, a charger 12, a charging port 13, a motor controller 20, and a battery controller 30.

[0012] The battery 1 is a drive source of the vehicle and is configured by connecting a plurality of secondary batteries in series or in parallel. The inverter 2 has a power conversion circuit in which a plurality of switching elements such as IGBTs and MOSFETs are connected for each phase. The inverter 2 switches on and off the switching elements according to a drive signal from the motor controller 20 as a control unit, converts the DC current output from the battery 1 into an AC current, outputs it to the drive motor 3, and drives the drive motor 3. Further, the inverter 2 inversely converts the AC power output by the regeneration of the drive motor 3 and outputs it to the battery 1. The inverter 2 has a connection circuit in which two switching elements per phase are connected in a bridge shape with three phases.

[0013] The drive motor 3 (hereinafter referred to as the motor 3) is a drive source of the vehicle and transmits a driving force to the drive wheels 6 and 7 via the reduction gear 4 and the drive shaft 5 during power running. Further, the motor 3 is rotated by being carried around by the drive wheels 6 and 7 during deceleration of the vehicle or the like, and generates a regenerative driving force to recover the kinetic energy of the vehicle as electric energy. As a result, the battery 1 is discharged by the power running of the motor 3 and charged by the regeneration of the motor 3. A wound field synchronous motor is used for the motor 3.

[0014] Further, the vehicle of this example includes a cooling mechanism that cools the motor 3 using a refrigerant. The cooling mechanism is configured such that the refrigerant circulates through the motor 3 and the battery 1, and during the warm-up control described later, the refrigerant that has increased in temperature by exchanging heat with the motor 3 warms the battery 1.

[0015] The voltage sensor 8 is a sensor that detects the voltage of the battery 1 and is connected between the battery 1 and the inverter 2. The detected value of the voltage sensor 8 is output to the motor controller 20 and the battery controller 30. The current sensor 9 is a sensor for detecting the current of the drive motor and is connected between the inverter 2 and the drive motor 3. The detected current of the current sensor 9 is output to the motor controller 20. The rotation sensor 10 is a sensor for detecting the rotational speed of the drive motor 3 and is composed of a resolver or the like. The detected value of the rotation sensor 10 is output to the motor controller 20.

[0016] The temperature sensor 11 is a sensor for detecting the stator temperature of the motor 3. The temperature sensor 11 is provided on the motor 3.

[0017] The charger 12 converts the power supplied from an external charging device via a charging plug connected to the charging port 13 into power suitable for charging the battery 1 and supplies it to the battery 1 to charge the battery 1. The output side of the charger 12 is electrically connected to the wiring connecting the battery 1 and the inverter 2. Therefore, the power output from the charger 12 can be supplied not only to the battery 1 but also to the inverter 2.

[0018] The charging port 13 is provided on the surface of the vehicle and has a connection port for connecting the charging plug. The charging plug is provided at the tip of a charging cable connected to an external charging device. When the charging plug is inserted into the charging port 13, power can be supplied from the external charging device to the battery 1 or the inverter 2.

[0019] The motor controller 20 includes the vehicle speed (V), the accelerator opening (APO), and the rotor phase (θ of the motor 3 re) Based on the current of the motor 3, the voltage of the battery 1, etc., a PWM control signal for operating the inverter 2 is created, and the PWM control signal is output to a driver circuit (not shown) that operates the inverter 2. Then, based on the PWM control signal, the driver circuit generates a drive signal for the switching element of the inverter 2 and outputs it to the inverter 2. Thereby, the motor controller 20 drives the motor 3 by operating the inverter 2.

[0020] The motor controller 20 switches between a normal motor control mode (normal control mode) for controlling the motor 3 to drive in response to a torque request due to a user's accelerator operation or the like, and a warm-up control mode for warming up the motor in a low-temperature state, and controls the inverter 2 and the motor 3. The motor controller 20 has a motor torque control unit 21 and a current control unit 22.

[0021] Based on a signal of vehicle information indicating vehicle variables input to the motor controller 20, the motor torque control unit 21 calculates a torque command value (T m1 * ) for causing the drive motor 3 to output a required torque by the user's operation or a required torque on the system.

[0022] A torque map (not shown) indicating the correlation between the motor speed and the torque command value, which is set for each accelerator opening, is stored in advance in the motor torque control unit 21. The torque map is set with a torque command value for efficiently outputting torque from the motor 3 with respect to the accelerator opening and the motor speed.

[0023] The motor speed is calculated based on the detection value of the rotation sensor 10. The accelerator opening is detected by an accelerator opening sensor (not shown). Then, the motor torque control unit 21 refers to the torque map and calculates a torque command value (T m1 * ) corresponding to the input accelerator opening (APO) and the motor speed.

[0024] Also, the motor torque control unit 21 limits the torque command value (T m1 * ) to calculate the torque command value (T m2 * ) and outputs it to the current control unit 22. When the temperature of the motor 3 increases, for example, when the stator temperature increases, the insulation performance of the coil 34 may deteriorate, and when the rotor temperature increases, there is a risk of demagnetization due to the heat of the permanent magnet. Therefore, when the temperature of the motor 3 is high, the motor torque control unit 21 limits the torque command value (T m1 * ) to suppress the torque command value below the limit value.

[0025] The current control unit 22 is a control unit that calculates a command value for the current flowing through the motor 3 based on the torque command value (T m2 * ) and controls the inverter 2 based on the command value. The current control unit 22 calculates a current command value for warm-up, which will be described later, in the warm-up mode.

[0026] The battery controller 30 manages the state of the battery 1 by calculating the state of charge (SOC: State of Charge) of the battery 1 based on the detected voltage of the voltage sensor 8. The battery controller 30 also controls the charger 12 to control the charging of the battery 1 by an external charging device.

[0027] When the battery controller 30 detects that the charging plug is inserted into the charging port 13, it calculates a voltage or current suitable for charging the battery 1 according to the state of the battery 1. Then, when power is supplied from an external charging device to the charger 12, the battery controller 30 controls the charger 12 to convert the input power to the charger 12 into the charging power of the battery 1 and supply power to the battery 1. When the SOC of the battery 1 reaches the target SOC, the battery controller 30 controls the charger 12 to stop the power supply from the charger 12 to the battery 1, and outputs a stop signal indicating the stop of charging to the external charging device via the charging cable.

[0028] Also, when a charging plug is inserted into the charging port 13, the battery controller 30 outputs a signal indicating that the power of an external charging device can be utilized to the motor controller 20. By receiving this signal, the motor controller 20 recognizes that it is possible to pass an electric current through the motor 3 using the power of the external charging device.

[0029] Note that based on the torque command value (T m1 * ) output from the motor torque control unit 21, a vibration damping control unit that calculates a torque command value (T m3 * ) for damping the torsional vibration of the drive shaft 5 by damping the drive motor 3 may be provided. In this case, the torque command value (T m3 * ) for damping the drive motor 3 is input to the current control unit 22.

[0030] Next, the warm-up control by the motor controller 20 will be described.

[0031] The friction of the motor 3 increases as the temperature decreases. Therefore, at low temperatures, the efficiency of the motor 3 decreases, and the power consumption performance of the vehicle deteriorates. Thus, in this example, warm-up control of the rotor is performed as described below. The motor controller 20 manages the temperature of the rotor of the motor 3 while the vehicle is stopped. The motor controller 20 uses the temperature sensor 11 to detect the stator temperature at a predetermined cycle and calculates the rotor temperature based on this. Alternatively, when the vehicle is stopped, the motor controller 20 detects the stator temperature with the temperature sensor 11, calculates the current stator temperature from the elapsed time since the vehicle was stopped and the outside air temperature, and obtains the rotor temperature by calculating the rotor temperature based on this.

[0032] FIG. 2 is an example of a cross-sectional view of the motor 3 used in this example. Specifically, it shows a part (one pole portion) of the cross-section of an 8-pole distributed winding motor. As shown in the figure, the stator (stator core) 32 has six slots 32A per pole, and stator coils 34 are arranged in each slot 32A. In the rotor (rotor core) 40, one concentrated winding type rotor coil 41 is arranged per pole. Note that the number of slots 32A, the shape of each part, and the winding method of the rotor coil 41 are not limited to this.

[0033] In the warm-up control of this example, the current command value of the axis (q-axis) corresponding to the torque component of the motor 3 is set to zero. For the axis (d-axis) corresponding to the excitation component, the current command value is alternately switched between the strengthening direction with respect to the magnetic flux direction of the rotor coil 41, that is, the current advance angle β = 270° (hereinafter also referred to as the positive side), and the weakening direction, that is, the current advance angle β = 90° (hereinafter also referred to as the negative side) at a predetermined period. As a result, an exciting current flows alternately in the positive and negative directions in the stator 32 of the motor 3, so that a magnetic flux is generated, and an eddy current flows in the rotor 31, causing the rotor to generate heat. Also, since the current flows alternately in the positive and negative directions, hysteresis loss occurs, and an eddy current continuously flows in the rotor 31. Thereby, the rotor 31 is warmed up without generating torque.

[0034] As shown in FIG. 2, when the current command value is in the strengthening direction, a magnetic flux in the same direction as the magnetic flux of the rotor coil 41 is generated, and when it is in the weakening direction, a magnetic flux in the opposite direction to the magnetic flux of the rotor coil 41 is generated.

[0035] Next, the control of the inverter 2 by the motor controller 20 will be described with reference to FIGS. 3 and 4. FIG. 3 is a flowchart showing a control flow for determining the necessity of warm-up control executed by the motor controller 20. FIG. 4 is a flowchart showing a control flow of warm-up control executed by the motor controller 20. Hereinafter, the description will be made according to the steps of each flowchart.

[0036] First, the control flow of FIG. 3 will be described.

[0037] In step S10, it is determined whether charging is in progress. If charging is in progress, the process of step S11 is executed; if not, the process of step S16 is executed. In step S16, it is determined whether the remaining amount C0 of the battery 1 is greater than a preset threshold C T If it is greater, the process of step S13 is executed. On the other hand, if it is less than or equal to the threshold C T , this control flow ends. The threshold C T is a threshold for determining whether warm-up is possible without external power supply, and is determined according to the capacity of the battery 1 used, the power required for warm-up of the motor 3 used, etc. Note that in step S10, in addition to the above determination of whether charging is in progress, it may also be determined whether to start charging. In this case, even if charging is not in progress, if charging is to start, the process of step S11 is executed. However, the processes after step S11 are executed after charging starts. Also, if charging is not in progress and charging is not to start, the process of step S16 is executed. Note that whether to start charging is determined based on, for example, the charging history recorded in the battery controller 30 or the like. For example, in light of the history of the charging start times so far, if it is estimated that charging will start several minutes from the current time, it is determined that charging will start.

[0038] In step S11, based on the detection signal of a temperature sensor (not shown) that detects the temperature of the battery 1, it is determined whether the current battery temperature T B0 is lower than a preset threshold T BT . If it is lower, the process of step S12 is executed; otherwise, this control flow ends. The determination in step S11 is for protecting the battery 1. When the motor 3 is warmed up, the battery 1 is also warmed up via the refrigerant. Therefore, if the warm-up control of the motor 3 is performed when the battery temperature is close to the allowable temperature, the battery temperature may exceed the allowable temperature. Thus, in step S11, it is determined whether the battery temperature exceeds the allowable temperature by performing the warm-up control of the motor 3. Therefore, the threshold T BTIt is the battery temperature at which even if there is a temperature rise due to the warm-up control of the motor 3, the allowable temperature is not exceeded, and it is a value determined by the heat capacity etc. of the battery 1 to be used.

[0039] In step S12, based on the detection signal of a temperature sensor (not shown) that detects the temperature of the refrigerant, the current refrigerant temperature T W0 is determined whether it is lower than a preset threshold value T WT If it is lower, the process of step S13 is executed, and if not, this control flow is terminated.

[0040] In step S13, it is determined whether the current stator temperature T S0 is lower than a preset threshold value T ST If it is lower, the process of step S14 is executed, and if not, this control flow is terminated. The determination in step S13 is for the protection of the stator 32. Although an insulating material for insulating the stator coil 34 is used for the stator 32, since the insulating material has an upper limit temperature at which the insulating performance can be maintained, if the warm-up control of the motor 3 is performed when the temperature of the stator 32 is close to the upper limit temperature, there is a risk of exceeding the upper limit temperature. Therefore, it is determined in step S13 whether the stator temperature exceeds the upper limit temperature by performing the warm-up control of the motor 3. Therefore, the threshold value T ST is the stator temperature at which even if there is a temperature rise due to the warm-up control of the motor 3, the upper limit temperature is not exceeded, and it is a value determined by the insulating material to be used.

[0041] Note that all or part of the determinations in steps S10 to S13 above may be omitted.

[0042] In step S14, it is determined whether the current rotor temperature T detected by the temperature sensor 11 R0 is lower than a preset threshold value T RT If it is lower, the process of step S15 is executed, and if not, this control flow is terminated. The threshold value T RT is the threshold value for the determination to start the warm-up control. The motor controller 20 determines that the current rotor temperature T R0 is the threshold value TRT If it is lower, it is determined that the rotor 31 is in a low temperature state and needs warming up. On the other hand, the current rotor temperature T R0 is higher than the threshold value T RT , it is determined that the rotor 31 is not in a low temperature state and does not need warming up. Note that the rotor temperature may be estimated from the temperature of the stator 32 detected by the temperature sensor 11, or may be estimated from the refrigerant temperature. Also, the temperature sensor 11 may be arranged to detect the rotor temperature, and the detected value of the temperature sensor 11 may be read. In this case, the stator temperature is estimated from the rotor temperature or the refrigerant temperature.

[0043] In step S15, warm-up control described later is executed.

[0044] Next, the control flow of FIG. 4 will be described. The said control flow is executed when it is determined to execute warm-up control in the control flow of FIG. 3.

[0045] In step S20, the energization period t of the d-axis current and the rotor current is set. In this example, the energization period (first period) of the d-axis current and the energization period (second period) of the rotor current are set to a preset fixed value (energization period t), but they may be variable values according to the rotor temperature and the stator temperature.

[0046] In step S21, the d-axis stator current command value I d90 at the current advance angle β = 90° (also referred to as the negative side) and the d-axis stator current command value I d270 at the current advance angle β = 270° (also referred to as the positive side) are set. In this example, the maximum allowable current I lim of the SW element for the stator of the inverter 2 is set as a fixed value, but it may be a variable value according to the stator temperature.

[0047] In step S22, the rotor current command value (also referred to as the lower limit value) i fmin at the current advance angle β = 90° and the rotor current command value (also referred to as the upper limit value) i fmax at the current advance angle β = 270° are set. In this example, as a fixed value, the lower limit value i fmin is set to zero, and the upper limit value ifmax be the maximum allowable current i of the SW element for the rotor of the inverter 2 lim However, it may be a variable value according to the rotor temperature. Note that the lower limit value i fmin may be a negative value, for example, -i lim is also acceptable.

[0048] In step S23, energization is performed for a preset time.

[0049] In step S24, it is determined whether the current rotor temperature T R0 is lower than the threshold value T RT If it is lower, the process of step S25 is executed. On the other hand, if the current rotor temperature T R0 is equal to or higher than the threshold value T RT it is considered that the warm-up has been completed, and this control flow is terminated.

[0050] In step S25, it is determined whether the current stator temperature T S0 is lower than the threshold value T ST If it is lower, the process returns to step S20 to continue the warm-up. On the other hand, if the current stator temperature T S0 is equal to or higher than the threshold value T ST this control flow is terminated for stator protection.

[0051] Figure 5 is a time chart of the d-axis current and the rotor current when the above warm-up control is performed. The solid line in the figure indicates the d-axis current, and the dashed line indicates the rotor current.

[0052] As shown in the figure, the phase of the positive d-axis current I d270 and the upper limit value i of the rotor current fmax , and the phase of the negative d-axis current I d90 and the lower limit value i of the rotor current fminThe phases overlap. In other words, when the d-axis current is on the positive side, the rotor current is also on the positive side, and when the d-axis current is on the negative side, the rotor current becomes zero. As a result, iron loss due to the positive d-axis current occurs when the rotor current is on the positive side, and iron loss due to the negative d-axis current occurs when the rotor current is zero. The conversion of these losses into heat promotes warm-up. Note that when the d-axis current and the rotor current are constant, no iron loss occurs, and only copper loss occurs.

[0053] By changing the rotor current in the winding field type motor 3 at a predetermined cycle as described above, more copper loss and iron loss can be generated compared to a permanent magnet type motor. That is, according to this example, the warm-up time can be shortened compared to a permanent magnet type motor. Further, according to this example, since the rotor 40 is directly heated, for example, in the case of a configuration in which the rotor 40 is cooled by a refrigerant, the warm-up time can be further shortened.

[0054] [Modification Example] Next, a modification example of this example will be described with reference to FIGS. 6 and 7. This modification example also belongs to the scope of the present invention in the same manner as this modification example.

[0055] FIG. 6 is a diagram showing the relationship between the rotor current, copper loss, and iron loss. FIG. 7 is a time chart of the rotor current and the d-axis current according to the modification example.

[0056] When the d-axis current is on the positive side, the magnetic field due to the rotor current is strengthened, and when the d-axis current is on the negative side, the magnetic field due to the rotor current is weakened. Therefore, as shown in FIG. 6, when the d-axis current is on the positive side, the greater the rotor current, the greater the iron loss, and when the d-axis current is on the negative side, the smaller the rotor current, the greater the iron loss.

[0057] Therefore, in order to make the iron loss even greater than in the above-described embodiment, as shown in FIG. 7, the lower limit value i fmin of the rotor current is set to a negative value, for example, -i lim . As a result, the iron loss due to the positive d-axis current increases when the rotor current is on the positive side, and the iron loss due to the negative d-axis current increases when the rotor current is on the negative side.

[0058] Also, as shown in FIG. 6, in the positive region of the rotor current, the copper loss increases as the rotor current increases, and in the negative region of the rotor current, the copper loss increases as the rotor current decreases. Therefore, according to this modification, the copper loss also increases when the rotor current is at the lower limit value.

[0059] That is, according to this modification, the copper loss and the iron loss can be increased to further shorten the warm-up time.

[0060] Note that even if the rotor current is changed only on the positive side as in the above-described embodiment, iron loss is generated due to the change in the rotor current. However, the rotor SW element of the inverter 2 includes an element that closes on the positive side and an element that closes on the negative side. When changing only on the positive side, one of the elements will remain closed. That is, when changing only on the positive side, only one of the elements will continue to generate heat. On the other hand, by switching the positive and negative of the rotor current at a predetermined cycle as in this modification, the rotor SW element of the inverter 2 can also be switched, and heat generation per element can be suppressed. Thereby, the current value can be increased to shorten the warm-up time.

[0061] Also, in a configuration in which the temperature of the battery 1 is increased by using the refrigerant whose temperature has risen due to the heat generation of the motor 3, since the heat capacity of the battery 1 is larger than the heat capacity of the motor 3, a situation may occur where the battery 1 has not reached the desired temperature even after the warm-up of the motor 3 is completed. In order to avoid such a situation, it is desirable to suppress the rate of increase in the temperature of the motor 3 and lengthen the warm-up time. Also in this case, switching the positive and negative of the rotor current at a predetermined cycle as in this modification to suppress heat generation per element is effective.

[0062] In the above-described embodiments and modifications, when the stator temperature and the rotor temperature are lower than their respective threshold values, the stator 32 and the rotor 40 are warmed up. However, the present invention is not limited to this. For example, the warm-up may be performed only on the stator 32 or only on the rotor 40. In this case, it is determined whether or not to warm up the stator 32 based on the stator temperature. If the stator temperature is lower than the threshold value T ST , the inverter 2 is controlled based on the above-described d-axis current command value to warm up the stator 32. On the other hand, it is determined whether or not to warm up the rotor 40 based on the rotor temperature. If the rotor temperature is lower than the threshold value T RT , the inverter 2 is controlled based on the above-described rotor current to warm up the rotor 40.

[0063] As described above, in the present embodiment, an electric motor control device for controlling the motor 3 (wound field type motor) for vehicle drive is provided. The control device includes a temperature sensor 11 (temperature acquisition device) that directly or indirectly acquires the stator temperature and the rotor temperature of the motor 3, an inverter 2 that converts and supplies electric power to the motor 3, and a motor controller 20 (control unit) that calculates the stator current command value and the rotor current command value of the motor 3 and controls the inverter 2 based on each current command value. The motor controller 20 calculates a warm-up stator current command value in which the stator current command value on the q-axis, which is the axis corresponding to the torque component of the motor 3, is zero, and the stator current command value on the d-axis, which is the axis corresponding to the excitation component of the motor 3, alternately changes in a first cycle between the positive side, which is the strengthening direction with respect to the rotor field direction, and the negative side, which is the weakening direction, and a warm-up rotor current command value in which the upper limit value and the lower limit value alternately change in a second cycle. Then, when the stator temperature is lower than the stator temperature threshold value for determining whether or not to warm up, the motor controller 20 performs warm-up using at least the warm-up stator current command value, and when the rotor temperature is lower than the rotor temperature threshold value for determining whether or not to warm up, the motor controller 20 performs warm-up using at least the warm-up rotor current command value. By setting the warm-up d-axis current command value and the warm-up rotor current command value as described above, not only copper loss but also iron loss can be generated, so that the warm-up time of the motor 3 can be shortened.

[0064] According to this embodiment, when the stator temperature is lower than the threshold value TST (stator temperature threshold value) for determining the necessity of warm-up and the rotor temperature is lower than the threshold value T RT (rotor temperature threshold value), the first period of the stator current command value for warm-up is made to coincide with the second period of the rotor current command value for warm-up, and the timing when the stator current command value on the d-axis becomes positive and the timing when the rotor current command value for warm-up becomes the upper limit value, and the timing when the stator current command value on the d-axis becomes negative and the timing when the rotor current command value for warm-up becomes the lower limit value are made to coincide respectively. Thereby, the iron loss can be increased and the warm-up time can be shortened.

[0065] According to a modification of this embodiment, the lower limit value of the rotor current command value for warm-up has the opposite sign to the upper limit value. Thereby, the copper loss and the iron loss can be made even larger than in the above embodiment.

[0066] According to this embodiment, the stator current command value for warm-up and the rotor current command value for warm-up are rectangular waves. Even if they are sine waves instead of rectangular waves, iron loss can be generated and the heat can be used for warm-up. However, by using rectangular waves, a current containing more high-frequency components can be made to flow through the motor 3, so that the warm-up time can be made shorter.

[0067] According to this embodiment, a refrigerant temperature acquisition device (not shown) for directly or indirectly acquiring the temperature of the refrigerant is provided, and the motor controller 20 stops the warm-up control when the temperature of the refrigerant exceeds a predetermined temperature. Thereby, excessive temperature rise of the motor 3 and the battery 1 due to the warm-up control can be prevented.

[0068] According to this embodiment, the motor controller 20 performs warm-up of the motor 3 when it is stopped. This is because the q-axis current that does not contribute to the torque of the motor 3 can be made zero when it is stopped.

[0069] Note that the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made within the scope of the technical idea described in the claims.

Description of Reference Numerals

[0070] 1 Battery, 2 Inverter, 3 Drive motor, 4 Reducer, 4 Drive shaft, 8 Voltage sensor, 9 Current sensor, 10 Rotation sensor, 11 Temperature sensor, 12 Charger, 13 Charging port, 20 Motor controller, 21 Motor torque control unit, 22 Current control unit, 30 Battery controller, 32 Stator, 32A Slot, 34 Stator coil, 40 Rotor, 41 Rotor coil

Claims

1. In an electric motor control device for controlling a wound-field motor for vehicle drive, a temperature acquisition device that directly or indirectly acquires the stator temperature and rotor temperature of the wound-field motor, an inverter that converts and supplies power to the wound-field motor, a control unit that calculates a stator current command value and a rotor current command value of the wound-field motor and controls the inverter based on each current command value, comprising: the control unit: a warm-up stator current command value in which the stator current command value on the q-axis, which is the axis corresponding to the torque component of the wound-field motor, is zero, and the stator current command value on the d-axis, which is the axis corresponding to the excitation component of the wound-field motor, changes alternately between the positive side, which is the field-weakening direction, and the negative side, which is the field-weakening direction, in a first cycle with respect to the rotor field direction; a warm-up rotor current command value in which the upper limit value and the lower limit value change alternately in a second cycle, and calculates: when the stator temperature is lower than a stator temperature threshold for determining the necessity of warm-up, performs warm-up using at least the warm-up stator current command value; when the rotor temperature is lower than a rotor temperature threshold for determining the necessity of warm-up, performs warm-up using at least the warm-up rotor current command value; when the stator temperature is lower than the stator temperature threshold for determining the necessity of warm-up and the rotor temperature is lower than the rotor temperature threshold for determining the necessity of warm-up, the first cycle of the warm-up stator current command value and the second cycle of the warm-up rotor current command value are made to coincide, and the timing when the stator current command value on the d-axis becomes the positive side and the timing when the warm-up rotor current command value becomes the upper limit value, and the timing when the stator current command value on the d-axis becomes the negative side and the timing when the warm-up rotor current command value becomes the lower limit value are made to coincide respectively. An electric motor control device characterized by this.

2. In the electric motor control device according to Claim 1, An electric motor control device, wherein the lower limit value of the rotor current command value for warm-up has the opposite sign to the upper limit value.

3. In the electric motor control device according to claim 1 or 2, An electric motor control device, wherein the stator current command value for warm-up and the rotor current command value for warm-up are rectangular waves.

4. In the electric motor control device according to any one of claims 1 to 3, comprising a refrigerant temperature acquisition device that directly or indirectly acquires the temperature of the refrigerant used for cooling the wound field magnet motor, An electric motor control device, wherein the control unit stops the warm-up when the temperature of the refrigerant exceeds a predetermined temperature.

5. In the electric motor control device according to any one of claims 1 to 4, An electric motor control device, wherein the control unit performs warm-up of the wound field magnet motor when the motor is stopped.

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