JP2016123168A - Drive unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress continuous generation of undulation in an electric current supplied to a motor.SOLUTION: When a control mode of an inverter is a PWM control mode, if continuation of the control mode results in a wave number Nw of carrier waves per 360 degrees of an electrical angle θe of a motor being less than a threshold value Nwref (S170, S180), a target voltage VH* for a high-voltage side power line is set such that the control mode of the inverter becomes a rectangular wave control mode (S190). Then, a step-up converter is controlled so that a voltage VH of the high-voltage side power line becomes equal to the target voltage VH* (S210).SELECTED DRAWING: Figure 2

Description

  The present invention relates to a drive device, and more particularly, to a drive device including a motor, an inverter, a battery, and a boost converter.

  Conventionally, as this kind of drive device, what is provided with a rotary electric machine, an inverter, a battery, a converter, and a control part is proposed (for example, refer to patent documents 1). The inverter drives the rotating electrical machine. The converter is connected to the battery and the inverter. This converter boosts the power from the battery and supplies it to the inverter, or steps down the power from the inverter and supplies it to the battery. The control unit controls the rotating electrical machine while smoothly switching between the PWM control mode and the rectangular wave control mode. The control unit performs calculations for each of the PWM control mode and the rectangular wave control mode when the rotational speed of the rotating electrical machine is equal to or less than the threshold value. Further, when the rotational speed of the rotating electrical machine is greater than the threshold value, the control unit determines that the control in the rectangular wave control mode is performed, performs the calculation for the rectangular wave control mode, and performs the calculation for the PMW control mode. Stop. As a result, the control unit can reduce the load caused by the extra calculation processing.

JP 2011-155787 A

  In recent years, in such a drive device, the region in which the rotating electrical machine (inverter) is controlled in the PWM control mode has been expanded to a higher rotational speed region of the rotating electrical machine. This is due to a decrease in the back electromotive voltage due to a reduction in the magnet amount of the rotating electrical machine. When the rotating electrical machine is controlled in the PWM control mode while the rotating electrical machine is rotating at a relatively high rotational speed, the wave number of the carrier wave (hereinafter referred to as the first wave number) per 360 degrees of the electrical angle of the rotating electrical machine is reduced. When the first wave number decreases, the current supplied to the rotating electrical machine may swell and continue. When the current continues to swell, the permanent magnet may be demagnetized due to the temperature rise of the rotating electrical machine due to the harmonic component caused by the swell. In this case, the controllability of the motor may be deteriorated. Therefore, it is required to suppress the occurrence of undulation in the current supplied to the rotating electrical machine.

  The main object of the drive device of the present invention is to suppress the occurrence of undulation in the current supplied to the motor.

  The drive device of the present invention employs the following means in order to achieve the main object described above.

The drive device of the present invention is
A motor,
An inverter for driving the motor;
Battery,
A boost converter connected to the first power line to which the inverter is connected and the second power line to which the battery is connected, and capable of boosting the power of the second power line and supplying the boosted power to the first power line;
Control means for controlling the inverter in a PWM control mode or a rectangular wave control mode so that the motor is driven with a target torque, and for controlling the boost converter so that the voltage of the first power line becomes a target voltage; ,
A drive device comprising:
The control means is means for controlling the inverter in a control mode based on the target torque and the voltage of the first power line among the PWM control mode and the rectangular wave control mode,
Further, when the control mode is the PWM control mode, when the first wave number, which is the wave number of a carrier wave per 360 degrees of the electrical angle of the motor, is less than a predetermined wave number, the control mode is Means for setting the target voltage to be in a rectangular wave control mode;
It is characterized by that.

  In the drive device of the present invention, the inverter is controlled in the PWM control mode or the rectangular wave control mode so that the motor is driven with the target torque, and the boost converter is controlled so that the voltage of the first power line becomes the target voltage. To do. Then, the inverter is controlled in a control mode based on the target torque and the voltage of the first power line among the PWM control mode and the rectangular wave control mode. Further, when the control mode is the PWM control mode, when the first wave number, which is the wave number of the carrier wave per 360 degrees of the electric angle of the motor, is less than the predetermined wave number, a target voltage is set so that the control mode becomes the rectangular wave control mode. To do. As a result, it is possible to suppress the occurrence of undulation in the current supplied to the motor. Here, “per 360 degrees of the electrical angle of the motor” means per period of a voltage command used for comparison with a carrier wave in the PWM control mode. In addition, when “the first wave number is less than the predetermined wave number”, when it is estimated that the first wave number is less than the predetermined wave number, and when it is detected that the first wave number is less than the predetermined wave number. And are included.

  In such a driving apparatus of the present invention, the control means estimates that the first wave number is less than the threshold when the control mode is the PWM control mode when the control mode is the rectangular wave control mode. In this case, the target voltage may be a means for setting the target voltage so that the control mode is maintained in the rectangular wave control mode.

  In the driving apparatus of the present invention, when the modulation rate based on the target torque and the voltage of the first power line is a predetermined modulation rate, the control unit controls the inverter in the rectangular wave control mode, When the modulation rate is less than the predetermined modulation rate, the inverter controls the inverter in the PWM control mode. Further, the control means has the first wave number when the control mode is the PWM control mode. The target voltage may be a means for setting the target voltage so that the modulation factor becomes the predetermined modulation factor when the value is less than the threshold value. In this case, when the control mode is the rectangular wave control mode and the control mode is the PWM control mode, the control means is configured such that the modulation factor is the predetermined modulation when the first wave number is less than the threshold. The target voltage may be set so as to be held at a rate.

  Further, in the driving apparatus of the present invention, the control means sets a minimum loss voltage of the first power line so that a total loss of the motor and the inverter is minimized, and the control mode is the PWM control mode. When the voltage of the first power line is set to the minimum loss voltage, the control mode is estimated to be the rectangular wave control mode, and the voltage of the first power line is set to the minimum loss voltage. When the control mode is maintained in the PWM control mode and the first wave number is estimated to be equal to or greater than the threshold, the minimum loss voltage is set to the target voltage, and the voltage of the first power line is set to the minimum loss voltage. When the control mode is maintained in the PWM control mode and the first wave number is estimated to be less than the threshold value Is a means for setting the target voltage and the control mode is the rectangular wave mode may be things.

It is a block diagram which shows the outline of a structure of the electric vehicle 20 carrying the drive device as one Example of this invention. It is a flowchart which shows an example of the pressure | voltage rise control routine performed by ECU50 of an Example. It is explanatory drawing which shows an example of the relationship between the voltage VH of the high voltage | pressure side electric power line and total loss when the target drive point of the motor 32 is a certain drive point. It is explanatory drawing which shows an example of the relationship between the voltage command Vu *, Vv *, Vw * of U phase, V phase, and W phase and the carrier wave per 360 degrees of the electrical angle θe of the motor 32. It is explanatory drawing which shows an example of a mode when a wave | undulation arises and continues when a wave | undulation does not arise in the electric current supplied to the motor. It is explanatory drawing which shows an example of the mode of the time change of the voltage VH of the high voltage | pressure side electric power line 42, the modulation factor Rm, and the control mode of the inverter. FIG. 11 is a configuration diagram showing an outline of a configuration of a hybrid vehicle 120 according to a modification. FIG. 11 is a configuration diagram showing an outline of a configuration of a hybrid vehicle 220 of a modified example.

  Next, the form for implementing this invention is demonstrated using an Example.

  FIG. 1 is a configuration diagram showing an outline of a configuration of an electric vehicle 20 equipped with a drive device as an embodiment of the present invention. The electric vehicle 20 according to the embodiment includes a motor 32, an inverter 34, a battery 36, a boost converter 40, and an electronic control unit (hereinafter referred to as ECU) 50, as illustrated.

  The motor 32 is configured as a known synchronous generator motor having a rotor in which a permanent magnet is embedded and a stator around which a three-phase coil is wound. The motor 32 is connected to a drive shaft 26 connected to the drive wheels 22 a and 22 b via a drive shaft (axle) 23 and a differential gear 24.

  The inverter 34 is connected to the boost converter 40 by the high voltage side power line 42. The inverter 34 includes six transistors T11 to T16 and six diodes D11 to D16. Two transistors T11 to T16 are arranged in pairs so as to be on the source side and the sink side with respect to the positive electrode bus and the negative electrode bus of the high voltage side power line 42, respectively. The six diodes D11 to D16 are respectively connected in parallel to the transistors T11 to T16 in the reverse direction. Each of the three-phase coils (U-phase, V-phase, W-phase) of the motor 32 is connected to each connection point between the transistors T11 to T16 as a pair. Therefore, when the voltage is applied to the inverter 34, the ECU 50 adjusts the ratio of the on-time of the paired transistors T11 to T16, thereby forming a rotating magnetic field in the three-phase coil and rotating the motor 32. Driven.

  The battery 36 is configured as, for example, a lithium ion secondary battery or a nickel hydride secondary battery.

  Boost converter 40 is connected to inverter 34 by high-voltage side power line 42 and to battery 36 by low-voltage side power line 44. Boost converter 40 includes two transistors T31 and T32, two diodes D31 and D32, and a reactor L. The transistor T31 is connected to the positive bus of the high voltage side power line 42. The transistor T32 is connected to the transistor T31 and the negative buses of the high voltage side power line 42 and the low voltage side power line 44. The two diodes D31 and D32 are respectively connected in parallel to the transistors T31 and T32 in the reverse direction. The reactor L is connected to a connection point between the transistors T31 and T32 and a positive bus of the low voltage side power line 44. The step-up converter 40 adjusts the ratio of the on-time of the transistors T31 and T32 by the motor ECU 40 to boost the power of the low-voltage side power line 44 and supply it to the high-voltage side power line 42 or the high-voltage side power line 42 42 is stepped down and supplied to the low voltage side power line 44. A smoothing capacitor 46 is attached to the positive and negative buses of the high-voltage power line 42. A smoothing capacitor 48 is attached to the positive and negative buses of the low-voltage power line 44.

  Although not shown, the ECU 50 is configured as a microprocessor centered on a CPU, and includes a ROM for storing processing programs, a RAM for temporarily storing data, an input / output port, and a communication port in addition to the CPU.

  Signals from various sensors are input to the ECU 50 via input ports. Examples of signals from various sensors include the following. The rotational position θm from the rotational position detection sensor 32a that detects the rotational position of the rotor of the motor 32. Phase currents Iu and Iv of the U phase and V phase of the motor 32 from current sensors 32u and 32v attached to a power line connecting the motor 32 and the inverter 34. A battery voltage Vb from a voltage sensor attached between the terminals of the battery 36. Battery current Ib from a current sensor attached to the output terminal of battery 36. A battery temperature Tb from a temperature sensor attached to the battery 36. The voltage VH of the capacitor 46 (high voltage side power line 42) from the voltage sensor 46a attached between the terminals of the capacitor 46. The voltage VL of the capacitor 48 (low voltage side power line 44) from the voltage sensor 48a attached between the terminals of the capacitor 48. An ignition signal from the ignition switch 60. A shift position SP from the shift position sensor 62 that detects the operation position of the shift lever 61. Accelerator opening degree Acc from the accelerator pedal position sensor 64 that detects the depression amount of the accelerator pedal 63. The brake pedal position BP from the brake pedal position sensor 66 that detects the amount of depression of the brake pedal 65. Vehicle speed V from the vehicle speed sensor 68.

  Various control signals are output from the ECU 50 via an output port. Examples of various control signals include the following. Switching control signal to transistors T11 to T16 of inverter 34. Switching control signal to transistors T31 and T32 of boost converter 40.

  The ECU 50 calculates the electrical angle θe and the rotational speed Nm of the motor 32 based on the rotational position θm of the rotor of the motor 32 detected by the rotational position detection sensor 32a. Further, the ECU 50 calculates the storage ratio SOC of the battery 36 based on the integrated value of the battery current Ib detected by the current sensor.

  In the electric vehicle 20 of the embodiment configured as described above, the ECU 50 first requires the required torque Td * required for traveling based on the accelerator opening Acc from the accelerator pedal position sensor 64 and the vehicle speed V from the vehicle speed sensor 68. Set. Subsequently, the required torque Td * is set to the torque command Tm * of the motor 32. Then, switching control of the transistors T11 to T16 of the inverter 34 is performed so that the motor 32 is driven by the torque command Tm *. The ECU 50 controls the boost converter 40 in addition to controlling the inverter 34. Control of boost converter 40 will be described later.

  Here, the control of the inverter 34 will be described. In the embodiment, the inverter 34 is performed by the ECU 50 in the pulse width modulation control (PWM control) mode or the rectangular wave control mode. The PWM control mode is a control mode in which the on-time ratio of the transistors T11 to T16 is adjusted by comparing the voltage command of the motor 32 and the carrier wave (triangular wave) voltage. The PWM control mode includes a sine wave control mode and an overmodulation control mode. The sine wave control mode is a control mode in which a pseudo three-phase AC voltage obtained by converting a sine wave voltage command having an amplitude equal to or smaller than the amplitude of the carrier wave is supplied to the motor 32 in the PWM control mode. The overmodulation control mode is a control mode in which an overmodulation voltage obtained by converting a sinusoidal voltage command having an amplitude larger than the amplitude of the carrier wave is supplied to the motor 32 in the PWM control mode. The rectangular wave control mode is a control mode for supplying a rectangular wave voltage to the motor 32. In the sine wave control mode, the modulation factor (voltage utilization factor) Rm is in the range of value 0 to value Rref1 (about 0.61). In the overmodulation control mode, the modulation factor Rm is in the range of the value Rref1 (about 0.61) to the value Rref2 (about 0.78). In the rectangular wave control mode, the modulation factor Rm is constant at a value Rref2 (about 0.78). The modulation factor Rm is defined as the ratio of the amplitude of the sinusoidal voltage command to the voltage VH of the high-voltage side power line 42 (the voltage command magnitude Vr described later).

  In the PWM control mode, the ECU 50 first inputs the U-phase and V-phase currents Iu and Iv of the motor 32, the electrical angle θe of the motor 32, and the torque command Tm * of the motor 32. Here, the values detected by the current sensors 32u and 32v are input as the phase currents Iu and Iv. As the electrical angle θe, a value calculated based on the rotational position θm of the rotor of the motor 32 detected by the rotational position detection sensor 32a is input. As the torque command Tm *, a value set by the drive control described above is input.

  Subsequently, the sum of the phase currents Iu, Iv, Iw flowing in the U-phase, V-phase, and W-phase of the three-phase coil of the motor 32 is set to 0, and the electric angle θe of the motor 32 is used to The phase currents Iu and Iv are coordinate-converted (three-phase to two-phase conversion) into d-axis and q-axis currents Id and Iq. Here, the d-axis is the direction of the magnetic flux formed by the permanent magnet embedded in the rotor of the motor 32. The q axis is a direction in which the electrical angle θe is advanced by π / 2 in the positive rotation direction of the motor 32 with respect to the d axis.

  Based on the torque command Tm * of the motor 32, d-axis and q-axis current commands Id * and Iq * are set. In this embodiment, the d-axis and q-axis current commands Id * and Iq * are determined in advance in accordance with a relationship between the torque command Tm * of the motor 32 and the d-axis and q-axis current commands Id * and Iq *. A current command setting map is stored in a ROM (not shown), and when a torque command Tm * of the motor 32 is given, corresponding d-axis and q-axis current commands Id * and Iq * are derived from the stored map. To be set. For example, the current command setting map is determined so that torque corresponding to the torque command Tm * can be output from the motor 32 and the magnitude Ir of the current command is minimized. The magnitude Ir of the current command is defined as the square root of the sum of the square of the current command Id * and the square of the current command Iq *.

  Next, using the d-axis and q-axis currents Id and Iq and the current commands Id * and Iq *, the difference between the d-axis and q-axis currents Id and Iq and the current commands Id * and Iq * is canceled out. In this way, the d-axis and q-axis voltage commands Vd * and Vq * are set. Subsequently, using the electrical angle θe of the motor 32, the d-axis and q-axis voltage commands Vd * and Vq * are coordinate-converted into U-phase, V-phase and W-phase voltage commands Vu *, Vv * and Vw * ( 2-phase to 3-phase conversion). The U-phase, V-phase, and W-phase voltage commands Vu *, Vv *, and Vw * are converted into PWM signals for switching the transistors T11 to T16 of the inverter 34. Then, by outputting a PWM signal to the inverter 34, switching control of the transistors T11 to T16 of the inverter 34 is performed. Here, the magnitude Vr of the voltage command is used as the amplitude of the sinusoidal voltage command used for the conversion of the PWM signal. The magnitude Vr of the voltage command is defined as the square root of the sum of the square of the voltage command Vd * and the square of the voltage flow command Vq *. The magnitude Vr of the voltage command is used for calculating the modulation factor Rm as the amplitude of the above-described sinusoidal voltage command. In the embodiment, the voltage command magnitude Vr and the modulation rate Rm are always calculated regardless of the control mode of the inverter 34.

  In the rectangular wave control mode, the ECU 50 first uses the electrical angle θe of the motor 32 to convert the U-phase and V-phase phase currents Iu and Iv into the d-axis and q-axis currents Id and Iq, as in the PWM control mode. To coordinate conversion (3-phase-2 phase conversion). Subsequently, an output torque Tmest that is estimated to be output from the motor 32 is set based on the d-axis and q-axis currents Id and Iq. Here, in the embodiment, the output torque Tmest is stored in a ROM (not shown) as an output torque estimation map in which the relationship between the d-axis and q-axis currents Id and Iq and the output torque Tmest is determined in advance through experiments and analysis. If the d-axis and q-axis currents Id and Iq are given, the corresponding output torque Tmest is derived and set from the stored map.

  Next, the voltage phase command θp * is calculated using the output torque Tm of the motor 32 and the torque command Tm * so that the difference between the output torque Tm and the torque command Tm * is canceled out. Subsequently, a rectangular wave signal is generated so that a rectangular wave voltage based on the voltage phase command θp * is applied to the motor 32. Then, by outputting a rectangular wave signal to the inverter 34, switching control of the transistors T11 to T16 of the inverter 34 is performed.

  In the embodiment, as described above, the voltage command magnitude Vr and the modulation factor Rm are constantly calculated. When the inverter 34 is controlled in the PWM control mode and the modulation factor Rm reaches the value Rref2 (about 0.78), the control mode of the inverter 34 is switched from the PWM control mode to the rectangular wave control mode. Further, when the inverter 34 is controlled in the rectangular wave control mode, if the modulation rate Rm becomes less than the value Rref2, the control mode of the inverter 34 is switched from the rectangular wave control mode to the PWM control mode.

  Next, the operation of the electric vehicle 20 of the embodiment thus configured, particularly the control of the boost converter 40 will be described. FIG. 2 is a flowchart illustrating an example of a boost control routine executed by the ECU 50 of the embodiment. This routine is executed repeatedly.

  When the boost control routine is designated, the ECU 50 first obtains data such as the torque command Tm * and the rotational speed Nm of the motor 32, the magnitude Vr of the voltage command, the modulation factor Rm, the current control mode Mdnw of the inverter 34, and the like. Input (step S100). Here, as the torque command Tm * of the motor 32, a value set by the above-described control is input. As the rotational speed Nm of the motor 32, a value calculated based on the rotational position θm of the rotor of the motor 32 detected by the rotational position detection sensor 32a is input. As the voltage command magnitude Vr and the modulation factor Rm, the values set by the above-described control are input. As the current control mode Mdnw of the inverter 34, the control mode currently used for the control of the inverter 34 among the PWM control mode and the rectangular wave control mode is input.

  When the data is input in this way, the minimum loss voltage VH1 of the high-voltage power line 42 is set based on the input target drive point (torque command Tm * and rotation speed Nm) of the motor 32 (step S110). Here, the minimum loss voltage VH1 of the high-voltage side power line 42 is a voltage of the high-voltage side power line 42 at which the total loss in the motor 32 and the inverter 34 is minimized. In this embodiment, the minimum loss voltage VH1 of the high-voltage side power line 42 is not shown as a minimum loss voltage setting map by predetermining the relationship between the target drive point of the motor 32 and the minimum loss voltage VH1 of the high-voltage side power line 42. When stored in the ROM and given the torque command Tm * and the rotational speed Nm, the minimum loss voltage VH1 of the corresponding high-voltage power line 42 is derived and set from the stored map. FIG. 3 is an explanatory diagram showing an example of the relationship between the voltage VH of the high-voltage power line 42 and the total loss when the target drive point of the motor 32 is a certain drive point. The minimum loss voltage setting map can be determined using such a relationship for each target drive point of the motor 32.

  Subsequently, the corresponding modulation factor Rm1 is calculated by dividing the magnitude Vr of the voltage command by the minimum loss voltage VH1 of the high-voltage power line 42 (step S120). Then, the corresponding control mode Md1 of the inverter 34 is set based on the corresponding modulation factor Rm1 (step S130). Here, the corresponding modulation factor Rm1 corresponds to the modulation factor Rm when the voltage VH of the high-voltage side power line 42 is set to the minimum loss voltage VH1. The corresponding control mode Md1 corresponds to the control mode of the inverter 34 when the voltage VH of the high-voltage power line 42 is set to the minimum loss voltage VH1.

  Next, it is determined whether the corresponding control mode Md1 is the PWM control mode or the rectangular wave control mode (step S140). When it is determined that the corresponding control mode Md1 is the rectangular wave control mode, the minimum loss voltage VH1 of the high-voltage side power line 42 is set to the target voltage VH * of the high-voltage side power line 42 (step S150). Then, the transistors T31 and T32 of the boost converter 40 are subjected to switching control so that the voltage VH of the high-voltage side power line 42 becomes the target voltage VH * (step S210), and this routine is finished. Thereby, the total loss in the motor 32 and the inverter 34 can be minimized. When the voltage VH of the high-voltage side power line 42 is the minimum loss voltage VH1, the inverter 34 is controlled in the corresponding control mode Md1 (in this case, the rectangular wave control mode).

  When it is determined in step S140 that the corresponding control mode Md1 is the PWM control mode, the corresponding wave number Nw is estimated based on the rotational speed Nm and the number of pole pairs p of the motor 32 and the carrier frequency fc (step S160). Here, the corresponding wave number Nw corresponds to 360 degrees of the electrical angle θe of the motor 32 when the inverter 34 is controlled in the corresponding control mode (in this case, the PWM control mode) (U phase, V phase, W phase voltage command). Vu *, Vv *, Vw * (per cycle). The carrier frequency fc is the frequency of the carrier wave. The corresponding wave number Nw can be easily obtained from the frequency of the electrical angle θe based on the rotation speed Nm of the motor 32 and the pole pair number p of the rotor and the carrier frequency fc. For reference, FIG. 4 shows an example of the relationship between the U-phase, V-phase, and W-phase voltage commands Vu *, Vv *, and Vw * and the carrier wave per 360 degrees of the electrical angle θe of the motor 32. FIG. 4 shows a state in which the wave number of the carrier wave per 360 degrees of the electrical angle θe of the motor 32 becomes the value 6.

  When the corresponding wave number Nw is estimated in this way, the estimated corresponding wave number Nw is compared with a threshold value Nwref (step S170). Here, the threshold value Nwref is a threshold value used to determine whether or not there is a possibility that the current supplied to the motor 32 will continue to swell. The threshold value Nwref is determined according to the specifications of the motor 32 and the inverter 34. For example, a value 6 or a value 9 can be used. In the PWM control mode, if the corresponding wave number Nw is small, the distortion of the voltage supplied to the motor 32 may increase, and the current supplied to the motor 32 may swell and continue. For reference, FIG. 5 shows an example of a state in which undulation occurs and continues when no undulation occurs in the current supplied to the motor 32. When the current supplied to the motor 32 swells and continues, the temperature of the motor 32 is likely to rise due to harmonic components caused by the swell, and the permanent magnet of the rotor of the motor 32 may be demagnetized. . Further, if the current supplied to the motor 32 continues to swell, the controllability of the motor 32 may deteriorate. In the process of step S170, when the inverter 34 is controlled in the corresponding control mode (in this case, the PWM control mode) with the voltage VH of the high-voltage side power line 42 as the minimum loss voltage VH1, the current supplied to the motor 32 swells. This is a process for determining whether or not there is a possibility of continuing.

  When the corresponding wave number Nw is greater than or equal to the threshold value Nwref in step S170, the minimum loss voltage VH1 of the high voltage side power line 42 is set to the target voltage VH * of the high voltage side power line 42 (step S150). Then, the transistors T31 and T32 of the boost converter 40 are subjected to switching control so that the voltage VH of the high-voltage side power line 42 becomes the target voltage VH * (step S210), and this routine is finished. Thereby, the total loss in the motor 32 and the inverter 34 can be minimized. When the voltage VH of the high-voltage side power line 42 is the minimum loss voltage VH1, the inverter 34 is controlled in the corresponding control mode Md1 (in this case, the PWM control mode).

  When the corresponding wave number Nw is less than the threshold value Nwref in step S170, it is determined whether the current control mode Mdnw of the inverter 34 is the PWM control mode or the rectangular wave control mode (step S180).

  When the current control mode Mdnw of the inverter 34 is the PWM control mode in step S180, the target voltage VH * of the high-voltage side power line 42 is set so that the modulation rate Rm changes from less than the value Rref2 to the value Rref2 (step S190). . Then, the transistors T31 and T32 of the boost converter 40 are subjected to switching control so that the voltage VH of the high-voltage side power line 42 becomes the target voltage VH * (step S210), and this routine is finished.

  Now, consider the case where it is determined in step S140 that the corresponding control mode Md1 is the PWM control mode, and in step S170, it is determined that the corresponding wave number Nw is less than the threshold value Nwref. Therefore, when the current control mode Mdnw of the inverter 34 is the PWM control mode in step S180, it means that when the current control mode Mdnw is continued for the inverter 34, the corresponding wave number Nw becomes the threshold value Nwref (estimated). To do.

  In the processing of steps S190 and S210, the modulation rate Rm is increased to a predetermined value Rref2 by decreasing the voltage VH of the high-voltage side power line 42 so that the control mode of the inverter 34 is switched from the PWM control mode to the rectangular wave control mode. It becomes processing to. By such processing, it is possible to prevent the current supplied to the motor 32 from swelling and continuing. In this case, the voltage VH of the high-voltage side power line 42 is relatively quick in order to further suppress the occurrence of undulation in the current supplied to the motor 32 (can be eliminated in a shorter time even if the undulation occurs). Alternatively, the voltage may be reduced at a rate that takes into account a certain degree of coexistence between suppression of the occurrence of undulation in the current and controllability of the boost converter 40.

  When the current control mode Mdnw of the inverter 34 is the rectangular wave control mode in step S180, the target voltage VH * of the high voltage side power line 42 is set so that the modulation factor Rm is held at the value Rref2 (step S200). Then, the transistors T31 and T32 of the boost converter 40 are subjected to switching control so that the voltage VH of the high-voltage side power line 42 becomes the target voltage VH * (step S210), and this routine is finished.

  Now, consider the case where it is determined in step S140 that the corresponding control mode Md1 is the PWM control mode, and in step S170, it is determined that the corresponding wave number Nw is less than the threshold value Nwref. Therefore, when the current control mode Mdnw of the inverter 34 is the rectangular wave control mode in step S180, it means that when the control mode of the inverter 34 is the PWM control mode, the wave number Nw becomes the threshold Nwref (estimated). To do.

  The processing of steps S200 and S210 is processing for holding the control mode of the inverter 34 in the rectangular wave control mode by holding the modulation factor Rm at the predetermined value Rref2. By such processing, it is possible to suppress undulation in the current supplied to the motor 32.

  FIG. 6 is an explanatory diagram illustrating an example of a temporal change in the voltage VH of the high-voltage power line 42, the modulation rate Rm, and the control mode of the inverter 34. As shown in the figure, at the time t1 during the control of the boost converter 40 and the inverter 34 in the PWM control mode so that the voltage VH of the high-voltage side power line 42 becomes the minimum loss voltage VH1, the corresponding wave number Nw Becomes less than the threshold value Nwref (it is estimated), the voltage VH of the high-voltage power line 42 is gradually reduced. As the voltage VH of the high-voltage side power line 42 decreases, the modulation factor Rm increases. When the modulation factor Rm reaches the predetermined value Rref2 at time t2, the control mode of the inverter 34 becomes the rectangular wave control mode. In this way, by setting the control mode of the inverter 34 to the rectangular wave control mode, it is possible to prevent the current supplied to the motor 32 from swelling and continuing.

  In the electric vehicle 20 of the embodiment described above, when the control mode of the inverter 34 is the PWM control mode and the control mode is continued, when the corresponding wave number Nw becomes less than the threshold value Nwref, the control mode of the inverter 34 is a rectangular wave. The target voltage VH * of the high voltage side power line 42 that is in the control mode is set, and the boost converter 40 is controlled so that the voltage VH of the high voltage side power line 42 becomes the target voltage VH *. As a result, it is possible to prevent the current supplied to the motor 32 from swelling and continuing.

  In the electric vehicle 20 of the embodiment, when the control mode of the inverter 34 is the PWM control mode, the control mode of the inverter 34 is the rectangular wave control mode when the corresponding wave number Nw is less than the threshold Nwref (estimated). The target voltage VH * of the high-voltage power line 42 is set. However, when the control mode of the inverter 34 is the PWM control mode, when the actual wave number Nwat of the carrier wave per 360 degrees of the electrical angle θe of the motor 32 becomes less than the threshold value Nwref (when this is detected), the inverter The target voltage VH * of the high-voltage power line 42 in which the control mode 34 is the rectangular wave control mode may be set. In this case, when the wave number Nwat becomes less than the threshold value Nwref (when this is detected), there is a possibility that the current supplied to the motor 32 is wavy, but the control mode of the inverter 34 is a rectangular wave. By setting the target voltage VH * of the high-voltage power line 42 that is in the control mode, the swell can be suppressed from continuing.

  In the embodiment, the electric vehicle 20 includes the motor 32, the inverter 34, the battery 36, and the boost converter 40. However, it is good also as a structure of the electric vehicle provided with two or more instead of only one motor. 7, in addition to the motor 32, the inverter 34, the battery 36, and the boost converter 40, the engine 122, the planetary gear 130, the motor 132, and the inverter 134 are included. It is good also as a structure provided. Planetary gear 130 is connected to engine 122, motor 132, and drive shaft 26. Inverter 134 drives motor 132 and exchanges power with battery 36. Furthermore, as shown in the hybrid vehicle 220 of the modified example of FIG. 8, in addition to the motor 32, the inverter 34, the battery 36, and the boost converter 40, an engine 222, a clutch 224, and a transmission 230 are provided. Also good. The engine 222 and the motor 32 are connected via a clutch 224. The transmission 230 is connected to the rotation shaft of the motor 32 and the drive shaft 26. In addition, the configuration may be a series type hybrid vehicle.

  The correspondence between the main elements of the embodiment and the main elements of the invention described in the column of means for solving the problems will be described. In the embodiment, the motor 32 corresponds to “motor”, the inverter 34 corresponds to “inverter”, the battery 36 corresponds to “battery”, the boost converter 40 corresponds to “boost converter”, and the booster of FIG. The ECU 50 that executes the control routine corresponds to “control means”.

  The correspondence between the main elements of the embodiment and the main elements of the invention described in the column of means for solving the problem is the same as that of the embodiment described in the column of means for solving the problem. Therefore, the elements of the invention described in the column of means for solving the problems are not limited. In other words, the interpretation of the invention described in the column of means for solving the problem should be made based on the description of the column, and the examples are those of the invention described in the column of means for solving the problem. It is only a specific example.

  As mentioned above, although the form for implementing this invention was demonstrated using the Example, this invention is not limited at all to such an Example, In the range which does not deviate from the summary of this invention, it is with various forms. Of course, it can be implemented.

  The present invention can be used in the manufacturing industry of electric vehicles.

  20 electric vehicle, 22a, 22b drive wheel, 23 drive shaft, 24 differential gear, 26 drive shaft, 32, 132 motor, 32a rotational position detection sensor, 32u, 32v current sensor, 34, 134 inverter, 36 battery, 40 boost converter , 42 High voltage side power line, 44 Low voltage side power line, 46, 48 Capacitor, 46a, 48a Voltage sensor, 50 Electronic control unit (ECU), 60 Ignition switch, 61 Shift lever, 62 Shift position sensor, 63 Accelerator pedal, 64 Accelerator pedal position sensor, 65 Brake pedal, 66 Brake pedal position sensor, 68 Vehicle speed sensor, 120, 220 Hybrid vehicle, 122, 222 Engine, 130 Planetary , 224 clutch, 230 transmission, D11-D16, D31, D32 diodes, L reactor, T11 to T16, T31, T32 transistor.

Claims (3)

A motor,
An inverter for driving the motor;
Battery,
A boost converter connected to the first power line to which the inverter is connected and the second power line to which the battery is connected, and capable of boosting the power of the second power line and supplying the boosted power to the first power line;
Control means for controlling the inverter in a PWM control mode or a rectangular wave control mode so that the motor is driven with a target torque, and for controlling the boost converter so that the voltage of the first power line becomes a target voltage; ,
A drive device comprising:
The control means is means for controlling the inverter in a control mode based on the target torque and the voltage of the first power line among the PWM control mode and the rectangular wave control mode,
Further, when the control mode is the PWM control mode, when the first wave number, which is the wave number of a carrier wave per 360 degrees of the electrical angle of the motor, is less than a predetermined wave number, the control mode is Means for setting the target voltage to be in a rectangular wave control mode;
A drive device characterized by that. The drive device according to claim 1,
When the control mode is the rectangular wave control mode and the control mode is estimated to be less than the threshold when the control mode is the PWM control mode, the control mode is Means for setting the target voltage to be held in a rectangular wave control mode;
Drive device. The drive device according to claim 1 or 2,
The control means controls the inverter in the rectangular wave control mode when the modulation rate based on the target torque and the voltage of the first power line is a predetermined modulation rate, and the modulation rate is less than the predetermined modulation rate. Sometimes it is means for controlling the inverter in the PWM control mode,
Further, when the control mode is the PWM control mode, the control means sets the target voltage so that the modulation factor becomes the predetermined modulation factor when the first wave number is less than the threshold value. Is,
A drive device characterized by that.

Images