Drive device

Abstract

To suppress actualization of a zero phase current caused by a dead time of switching of a plurality of first and second switching elements of first and second inverters.SOLUTION: The drive device sets a current phase for dead-time correction of each phase based on current phases of current commands of a d-axis and a q-axis and an electrical angle of the motor, sets a positive or negative dead-time correction value of each phase based on a relationship between the current phase for dead-time correction of each phase and a phase of a phase current zero, corrects a voltage command of each phase using the dead-time correction value of each phase to set a corrected voltage command of each phase, and controls the first and second inverters using the corrected voltage command of each phase.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a drive device. [Background technology]

[0002] Conventionally, a drive device has been proposed that includes first and second power storage devices, a motor having a three-phase coil, and first and second inverters that are connected to first and second power lines to which the first and second power storage devices are connected, and that are connected to one end and the other end of the three-phase coil and have a plurality of first and second switching elements (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-5394 Summary of the Invention [Problem to be solved by the invention]

[0004] Meanwhile, a drive device has also been proposed that includes a power storage device, a motor having a three-phase coil, and first and second inverters connected to a power line to which the power storage device is connected and having a plurality of first and second switching elements connected to one end and the other end of the three-phase coil. In such a drive device in which the first and second inverters and the motor are H-connected, there is a problem in that a zero-phase current of the electric tertiary order (current flowing in the same phase through the first inverter, motor, second inverter, power line, and first inverter) becomes apparent due to the dead time of the switching of the plurality of first and second switching elements. The drive device disclosed herein primarily aims to suppress the appearance of the zero-phase current caused by the dead time of the switching of the plurality of first and second switching elements of the first and second inverters. [Means for solving the problem]

[0005] The driving device of the present disclosure employs the following means to achieve the above-mentioned main object. a control device that sets d-axis and q-axis current commands based on a torque command of the motor, sets voltage commands for each phase based on the d-axis and q-axis current commands, and controls the first and second inverters using the voltage commands for each phase, wherein the control device sets a dead time correction current phase for each phase based on a current phase of the d-axis and q-axis current commands and an electrical angle of the motor, sets a positive or negative dead time correction value for each phase based on a relationship between the dead time correction current phase for each phase and a phase of zero phase current, corrects the voltage command for each phase using the dead time correction value for each phase to set a corrected voltage command for each phase, and controls the first and second inverters using the corrected voltage commands for each phase.

[0006] In the drive device disclosed herein, a current phase for dead time correction of each phase is set based on the current phases of the d-axis and q-axis current commands and the electrical angle of the motor, a positive or negative dead time correction value for each phase is set based on the relationship between the current phase for dead time correction of each phase and the phase of zero phase current, a voltage command for each phase is corrected using the dead time correction value for each phase to set a corrected voltage command for each phase, and the first and second inverters are controlled using the corrected voltage command for each phase. This makes it possible to suppress the emergence of zero-phase current caused by dead time in the switching of multiple first and second switching elements of the first and second inverters, and to suppress heat generation and deterioration in power consumption (energy efficiency) of the motor and the first and second inverters. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a schematic diagram of an electric vehicle 10 equipped with a drive device according to an embodiment. [Figure 2]10 is a flowchart illustrating an example of a corrected voltage command calculation process. [Figure 3] 3 is an explanatory diagram showing an example of the phase currents Iu, Iv, Iw of each phase of the motor 20 and the zero-phase current (Iu+Iv+Iw). FIG. DETAILED DESCRIPTION OF THE INVENTION

[0008] A mode (embodiment) for carrying out the present disclosure will be described with reference to the drawings. Fig. 1 is a schematic configuration diagram of an electric vehicle 10 equipped with a drive device according to an embodiment of the present disclosure. As shown in the figure, the electric vehicle 10 of the embodiment includes a motor 20, first and second inverters 22, 24, a battery 26 as an electricity storage device, and an electronic control unit (hereinafter referred to as "ECU") 50 as a control device.

[0009] The motor 20 is configured as a three-phase AC motor having, for example, a rotor with a permanent magnet embedded in a rotor core and a stator with three-phase (U-phase, V-phase, W-phase) coils wound around a stator core. The rotor is connected to a drive shaft that is connected to drive wheels via a differential gear. The first and second inverters 22, 24 are connected to power lines 28 (positive line 28p and negative line 28n) to which a battery 26 is connected, and are also connected to one end and the other end of the three-phase coils of the motor 20. The first inverter 22 includes six transistors T11-T16 as switching elements and six diodes D11-D16 connected in parallel to the six transistors T11-T16, respectively. The transistors T11-T16 are arranged in pairs, two on the source side and two on the sink side of the positive line 28p and the negative line 28n. Each of the connection points of two pairs of transistors T11 to T16 is connected to one end of the three-phase coil of the motor 20. Similar to the first inverter 22, the second inverter 24 includes six transistors T21 to T26 as switching elements and six diodes D21 to D26. The transistors T21 to T26 are arranged in pairs, two on the source side and two on the sink side of the positive line 28p and the negative line 28n. Each of the connection points of two pairs of transistors T21 to T26 is connected to the other end of the three-phase coil of the motor 20. The battery 26 is configured as, for example, a lithium-ion secondary battery or a nickel-metal hydride secondary battery, and is connected to a power line 28 (positive line 28p and negative line 28n). A smoothing capacitor 30 is connected to the power line 28. In this embodiment, the power line 28 is connected in the following order: battery 26, capacitor 30, first inverter 22, and second inverter 24.

[0010] The ECU 50 includes a microcomputer having a CPU, ROM, RAM, flash memory, input / output ports, and communication ports, as well as various drive circuits and logic ICs. Signals are input to the ECU 50 from various sensors. For example, the rotational position θm of the rotor of the motor 20 is input from a rotational position sensor 22a, and the phase currents Iu, Iv, and Iw of the motor 20 are input from current sensors 22u, 22v, and 22w. The ECU 50 also receives the voltage Vb of the battery 26 from a voltage sensor 26v, the current Ib of the battery 26 from a current sensor 26i, the temperature Tb of the battery 26 from a temperature sensor 26t, and the voltage VH of the capacitor 30 (power line 28) from a voltage sensor 30v. Also input to the ECU 50 are an on / off signal from a power switch 60, the operating position of a shift lever 61 (shift position SP) from a shift position sensor 62, the depression amount of an accelerator pedal 63 (accelerator opening Acc) from an accelerator pedal position sensor 64, the depression amount of a brake pedal 65 (brake pedal position BP) from a brake pedal position sensor 66, and a vehicle speed V from a vehicle speed sensor 67. The ECU 50 outputs switching control signals to the transistors T11 to T16 and T21 to T26 of the first and second inverters 22, 24. The ECU 50 calculates the electrical angle θe and rotation speed Nm of the motor 20 based on the rotational position θm of the rotor of the motor 20, and calculates the charge storage rate SOC of the battery 26 based on the integrated value of the current Ib of the battery 26.

[0011] In the electric vehicle 10 of this embodiment, the ECU 50 sets a required torque Td* required for traveling based on the accelerator pedal position Acc and the vehicle speed V, sets a torque command Tm* for the motor 20 so that the vehicle travels at the set required torque Td*, and performs switching control of the transistors T11-T16 and T21-T26 of the first and second inverters 22 and 24 based on the set torque command Tm*. The control of the first and second inverters 22 and 24 will now be described. The ECU 50 first performs a coordinate transformation (three-phase-to-two-phase transformation) of the phase currents Iu, Iv, and Iw of the motor 20 into d-axis and q-axis currents Id and Iq using the electrical angle θe of the motor 20, and sets the d-axis and q-axis current commands Id* and Iq* based on the torque command Tm* for the motor 20. Next, d-axis and q-axis voltage commands Vd*, Vq* are calculated by current feedback control so that the differences between the d-axis and q-axis current commands Id*, Iq* and the currents Id, Iq are canceled out. Then, using the electrical angle θe, the d-axis and q-axis voltage commands Vd*, Vq* are coordinate-transformed (2-phase to 3-phase transformation) to voltage commands Vu*, Vv*, Vw* for each phase, and the resulting voltage commands Vu*, Vv*, Vw* for each phase are subjected to dead-time correction (described later) to calculate corrected voltage commands Vuad*, Vvad*, Vwad* for each phase. Furthermore, by comparing the corrected voltage commands Vuad*, Vvad*, Vwad* of each phase with the carrier voltage (triangular wave voltage), PWM signals for the transistors T11 to T16, T21 to T26 of the first and second inverters 22, 24 are generated to control the switching of the transistors T11 to T16, T21 to T26.

[0012] Next, the operation of the electric vehicle 10, particularly the process of calculating corrected voltage commands Vuad*, Vvad*, Vwad* for each phase by performing dead time correction on the voltage commands Vu*, Vv*, Vw* for each phase, will be described. Figure 2 is a flowchart showing an example of the corrected voltage command calculation process repeatedly executed by the ECU 50.

[0013] When this routine is executed, the ECU 50 calculates a dead time base correction value Vdtbs according to equation (1) using the dead time Dt of the switching of the transistors T11-T16 and T21-T26 of the first and second inverters 22 and 24, the carrier frequency fc of the carrier voltage, and the voltage VH of the capacitor 30 (power line 28) (step S100). The dead time Dt and the carrier frequency fc may each be constant values ​​or may be variable values ​​based on the rotation speed Nm of the motor 20, etc.

[0014] Vdtbs=Dt·fc·(VH / 2) (1)

[0015] Next, the current phase θi based on the q axis in the dq coordinate system is calculated as the arc tangent of the value obtained by dividing the q axis current command Iq* by the d axis current command Id* (step S110). Then, 90 [deg] is subtracted from the sum of the current phase θi and the electrical angle θe to calculate a base current phase θdtbs for dead time correction (step S120). Furthermore, the base current phase θdtbs, the value obtained by subtracting 120 [deg] from the base current phase θdtbs, and the value obtained by subtracting 240 [deg] from the base current phase θdtbs are set as the current phases θudt, θvdt, and θwdt for dead time correction of each phase (U phase, V phase, W phase) (0 [deg≦θudt, θvdt, θwdt<360 [deg]) (step S130). In the embodiment, the phase currents Iu, Iv, and Iw of each phase are set so that the current phases θudt, θvdt, and θwdt for dead time correction cross from positive to zero and become negative at 0 [deg], and cross from negative to zero and become positive at 180 [deg].

[0016] After the current phases θudt, θvdt, and θwdt for dead time correction of each phase are set in this manner, it is determined whether the current phase θudt for dead time correction for the U phase is less than 180 degrees (step S140). If it is determined that the current phase θudt for dead time correction is less than 180 degrees, the dead time correction value Vudt is set to the dead time base correction value Vdtbs (step S142). On the other hand, if it is determined that the current phase θudt for dead time correction is 180 degrees or more, the dead time correction value Vudt is set to a value obtained by multiplying the dead time base correction value Vdtbs by −1 (step S144). Similarly, for the V and W phases, when the current phases θvdt and θwdt for dead time correction are less than 180 degrees, the dead time correction values ​​Vvdt and Vwdt are set to the dead time base correction value Vdtbs, and when the current phases θvdt and θwdt for dead time correction are 180 degrees or greater, the dead time correction values ​​Vvdt and Vwdt are set to the value obtained by multiplying the dead time base correction value Vdtbs by -1 (steps S150 to S154, S160 to S164). Then, dead time correction is performed by adding the dead time correction values ​​Vudt, Vvdt, and Vwdt to the voltage commands Vu*, Vv*, and Vw* of each phase, and corrected voltage commands Vuad*, Vvad*, and Vwad* for each phase are calculated (step S170), after which this routine ends.

[0017] FIG. 3 is an explanatory diagram showing an example of the phase currents Iu, Iv, and Iw of each phase of the motor 20. FIG. 3(A) shows the embodiment, and FIG. 3(B) shows the comparative example. The embodiment and the comparative example have the same torque command Tm* and rotation speed Nm. In the comparative example, dead time correction is not performed. That is, in the comparative example, PWM signals for the transistors T11-T16 and T21-T26 of the first and second inverters 22 and 24 are generated by comparing the voltage commands Vu*, Vv*, and Vw* of each phase with the carrier voltage (triangular wave voltage), thereby controlling the switching of the transistors T11-T16 and T21-T26. In the comparative example, as shown in FIG. 3(B), the phase currents Iu, Iv, and Iw of each phase are distorted near zero. It was also found that the maximum value and effective value of the zero-phase current (Iu + Iv + Iw) became large. In contrast, in the embodiment, as shown in FIG. 3A, distortion of the phase currents Iu, Iv, and Iw of each phase near zero is suppressed. It was also found that the maximum value and effective value of the zero-phase current are suppressed. This is thought to be because, in the comparative example, the zero-phase current of the electric third order is manifested due to the dead time of the switching of transistors T11 to T16 and T21 to T26, whereas in the embodiment, the manifestation of the zero-phase current is suppressed by dead time correction. By suppressing the manifestation of the zero-phase current, it is possible to suppress heat generation and deterioration of power consumption (energy efficiency) of the motor 20 and the first and second inverters 22 and 24.

[0018] In the drive device mounted on the electric vehicle 10 according to the embodiment described above, the current phases θudt, θvdt, and θwdt for dead time correction of each phase are set based on the current phases θi of the d-axis and q-axis current commands Id* and Iq* and the electrical angle θe of the motor 20, and the dead time correction value Vu for each phase is calculated based on the magnitude relationship between the current phases θudt, θvdt, and θwdt for dead time correction of each phase and 180 [deg] (the phase at which the phase current is zero). The dead time correction values ​​Vudt, Vvdt, Vwdt for each phase are set, and the voltage commands Vu*, Vv*, Vw* for each phase are corrected using the dead time correction values ​​Vudt, Vvdt, Vwdt for each phase to set corrected voltage commands Vuad*, Vvad*, Vwad* for each phase, and the corrected voltage commands Vuad*, Vvad*, Vwad* for each phase are used to control the switching of the transistors T11 to T16, T21 to T26 of the first and second inverters 22, 24. This makes it possible to suppress the emergence of zero-phase current caused by the dead time in the switching of the transistors T11 to T16, T21 to T26, and to suppress heat generation and deterioration in power consumption (energy efficiency) of the motor 20 and the first and second inverters 22, 24.

[0019] In the above-described embodiment, the drive unit is mounted on an electric vehicle 10 equipped with a motor 20, but is not limited to this. For example, the drive unit may be mounted on a hybrid vehicle equipped with an engine in addition to a motor, or on a fuel cell vehicle equipped with a fuel cell in addition to a motor. The drive unit may also be mounted on a moving object other than a vehicle or on stationary construction equipment.

[0020] The correspondence between the main elements of the embodiment and the main elements of the invention described in the "Means for Solving the Problem" section will be described below. In the embodiment, the battery 26 corresponds to the "electricity storage device," the motor 20 corresponds to the "motor," the first and second inverters 22, 24 correspond to the "first and second inverters," and the ECU 50 corresponds to the "control device."

[0021] The correspondence between the main elements of the embodiments and the main elements of the invention described in the "Means for Solving the Problem" section does not limit the elements of the invention described in the "Means for Solving the Problem" section, since the embodiments are examples for specifically explaining the mode for implementing the invention described in the "Means for Solving the Problem" section. In other words, the interpretation of the invention described in the "Means for Solving the Problem" section should be based on the description in that section, and the embodiments are merely specific examples of the invention described in the "Means for Solving the Problem" section.

[0022] The above describes the forms for implementing the present disclosure using embodiments, but the present disclosure is not limited to these embodiments in any way, and it goes without saying that the present disclosure can be implemented in various forms within the scope that does not deviate from the gist of the present disclosure. [Industrial Applicability]

[0023] The present disclosure is applicable to industries such as the drive device manufacturing industry. [Explanation of symbols]

[0024] 20 motor, 22 first inverter, 22a rotational position sensor, 22u, 22v, 22w current sensors, 24 second inverter, 50 ECU, D11 to D16, D21 to D26 diodes, T11 to T16, T21 to T26 transistors.

Claims

[Claim 1] a power storage device; a motor having a three-phase coil; a first inverter connected to a power line to which the power storage device is connected and connected to one end of the three-phase coil, the first inverter having a plurality of first switching elements; a second inverter connected to the power line and to the other end of the three-phase coil, the second inverter having a plurality of second switching elements; a control device that sets d-axis and q-axis current commands based on a torque command of the motor, sets voltage commands for each phase based on the d-axis and q-axis current commands, and controls the first and second inverters using the voltage commands for each phase; A drive device comprising: the control device sets a current phase for dead time correction of each phase based on the current phases of the d-axis and q-axis current commands and the electrical angle of the motor, sets a positive or negative dead time correction value for each phase based on the relationship between the current phase for dead time correction of each phase and a phase of zero phase current, corrects the voltage command for each phase using the dead time correction value for each phase to set a corrected voltage command for each phase, and controls the first and second inverters using the corrected voltage command for each phase. Drive unit.

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