Drive device

Abstract

The present invention suppresses a dominant phenomenon of a zero-sequence current caused by a dead time of switching of a plurality of first and second switching elements of first and second inverters. The drive device sets a current phase for dead time correction for each phase on the basis of the current phase of a d-axis and q-axis current command and the electrical angle of the motor, and sets a positive or negative dead time correction value for each phase on the basis of the relationship between the current phase for dead time correction for each phase and the phase at which the phase current is zero. The dead time correction value for each phase is used to correct the voltage command for each phase and set a corrected voltage command for each phase, and the corrected voltage command for each phase is used to control the first inverter and the second inverter.

Description

TECHNICAL FIELD

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

[0002] In the past, a drive device has been proposed that includes a first and a second electric power storage device, a motor having a three-phase coil, and a first and a second inverter connected to a first and a second electric power line to which the first and the second electric power storage device are connected, and connected to one end side and the other end side of the three-phase coil, and having a plurality of first and second switching elements (see, for example, Patent Literature 1).

[0003] Patent Literature 1: Japanese Patent Application Publication No. 2020-5394

[0004] In addition, a drive device has been proposed that includes an electric power storage device, a motor having a three-phase coil, and a first and a second inverter connected to an electric power line to which the electric power storage device is connected, and connected to one end side and the other end side of the three-phase coil, and having a plurality of first and second switching elements. In such a drive device in which the first and the second inverters and the motor are connected by an H-bridge, a problem occurs in which, due to a dead time of switching of the plurality of first and second switching elements, a zero sequence current (a current flowing in the first inverter, the motor, the second inverter, the electric power line, and the first inverter in the same phase) of the electrical third order is made explicit. The main object of the drive device of the present disclosure is to suppress the phenomenon of explicitness of the zero sequence current caused by the dead time of switching of the plurality of first and second switching elements of the first and the second inverters. SUMMARY

[0005] The drive device of the present disclosure adopts the following means in order to achieve the main object described above. The drive device of the present disclosure includes an electric power storage device, a motor having a three-phase coil, a first inverter connected to an electric power line to which the electric power storage device is connected, and connected to one end side of the three-phase coil, and having a plurality of first switching elements, a second inverter connected to the electric power line, and connected to the other end side of the three-phase coil, and having a plurality of second switching elements, and a control device that sets current commands of d- and q-axes based on a torque command of the motor, sets voltage commands of phases based on the current commands of the d- and q-axes, controls the first and the second inverters using the voltage commands of the phases, sets current phases for dead time correction of the phases based on the current phases of the current commands of the d- and q-axes and an electric angle of the motor, sets positive or negative dead time correction values of the phases based on a relationship between the current phases for dead time correction of the phases and phases of zero of phase currents, sets corrected voltage commands of the phases by correcting the voltage commands of the phases using the dead time correction values of the phases, and controls the first and the second inverters using the corrected voltage commands of the phases.

[0006] In the drive device of the present disclosure, a current phase for dead-time correction of each phase is set based on the current phase of the current command of the d-axis and q-axis and the electrical angle of the motor, a positive or negative dead-time correction value of each phase is set based on the relationship between the current phase for dead-time correction of each phase and the phase at which the phase current is zero, the voltage command of each phase is corrected using the dead-time correction value of each phase and the corrected voltage command of each phase is set, and the first and second inverters are controlled using the corrected voltage command of each phase. Thus, the explicit phenomenon of zero-sequence current caused by the dead-time of the switching of the plurality of first and second switching elements of the first and second inverters can be suppressed, and the deterioration of the heat generation, power consumption (energy efficiency) of the motor, first and second inverters can be suppressed. BRIEF DESCRIPTION OF DRAWINGS

[0007] Figure 1 is a schematic configuration view of an electric vehicle 10 to which the drive device of the embodiment is mounted.

[0008] Figure 2 is a flowchart showing an example of the corrected voltage command operation processing.

[0009] Figure 3 is an explanatory view showing an example of the phase currents Iu, Iv, Iw of each phase of the motor 20 and the zero-sequence current (Iu + Iv + Iw).

[0010] BRIEF DESCRIPTION OF DRAWINGS:

[0011] 20 motor, 22 first inverter, 22a rotational position sensor, 22u, 22v, 22w current sensor, 24 second inverter, 50 ECU, D11 to D16, D21 to D26 diode, T11 to T16, T21 to T26 transistor. DETAILED DESCRIPTION

[0012] An embodiment (embodiment) for implementing the present disclosure is described with reference to the drawings. Figure 1 is a schematic configuration view of an electric vehicle 10 to which the drive device of the embodiment of the present disclosure is mounted. As shown in the figure, the electric vehicle 10 of the embodiment is provided with a motor 20, first and second inverters 22, 24, a battery 26 as an electric storage device, and an electronic control unit (hereinafter, referred to as "ECU") 50 as a control device.

[0013] The motor 20 is configured as a three-phase alternating-current motor, for example, having a rotor in which a permanent magnet is embedded in a rotor core, and a stator in which three-phase (U-phase, V-phase, W-phase) coils are wound in a stator core. The rotor is connected to a drive shaft that is linked to a drive wheel 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 to one end side and the other end side of the three-phase coils of the motor 20. The first inverter 22 is provided with six transistors T11 to T16 as switching elements, and six diodes D11 to D16 connected in parallel to the six transistors T11 to T16, respectively.

[0014] The transistors T11 to T16 are arranged in pairs of two in a manner that the positive line 28p and the negative line 28n become the source side and the drain side, respectively. The connection points of the paired two transistors of the transistors T11 to T16 are connected to the one end side of the three-phase coils of the motor 20, respectively. The second inverter 24 is provided with six transistors T21 to T26 as switching elements and six diodes D21 to D26, similarly to the first inverter 22. The transistors T21 to T26 are arranged in pairs of two in a manner that the positive line 28p and the negative line 28n become the source side and the drain side, respectively. The connection points of the paired two transistors of the transistors T21 to T26 are connected to the other end side of the three-phase coils of the motor 20, respectively. The battery 26 is configured as a lithium-ion secondary battery or a nickel-hydrogen secondary battery, for example, and is connected to the power lines 28 (positive line 28p and negative line 28n). A capacitor 30 for smoothing is connected to the power lines 28. In the embodiment, the battery 26, the capacitor 30, the first inverter 22, and the second inverter 24 are connected in this order in the power lines 28.

[0015] The ECU 50 is provided with a microcomputer having a CPU, a ROM, a RAM, a flash memory, input and output ports, communication ports, various drive circuits, and various logic ICs. Signals from various sensors are input to the ECU 50. For example, the rotational position θm of the rotor of the motor 20 from the rotational position sensor 22a, the phase currents Iu, Iv, Iw of the respective phases of the motor 20 from the current sensors 22u, 22v, 22w are input. Also, the voltage Vb of the battery 26 from the voltage sensor 26v, the current Ib of the battery 26 from the current sensor 26i, the temperature Tb of the battery 26 from the temperature sensor 26t, the voltage VH of the capacitor 30 (power line 28) from the voltage sensor 30v are input. The on-off signal from the power switch 60, the operation position (gear position SP) of the shift lever 61 from the gear position sensor 62, the depression amount (accelerator opening degree Acc) of the accelerator pedal 63 from the accelerator pedal position sensor 64, the depression amount (brake pedal position BP) of the brake pedal 65 from the brake pedal position sensor 66, the vehicle speed V from the vehicle speed sensor 67 are also input. Switching control signals are output from the ECU 50 to the transistors T11 to T16, T21 to T26 of the first inverter 22, the second inverter 24. The ECU 50 calculates the electric angle θe, the rotational speed Nm of the motor 20 based on the rotational position θm of the rotor of the motor 20, or calculates the state of charge SOC of the battery 26 based on the cumulative value of the current Ib of the battery 26.

[0016] In the electric vehicle 10 of the embodiment, the ECU 50 sets a required torque Td* required for running based on the accelerator opening Acc and the vehicle speed V, sets a torque command Tm* of the motor 20 in a manner to run with the set required torque Td*, and performs switching control of the transistors T11 to T16, T21 to T26 of the first and second inverters 22, 24 based on the set torque command Tm*. Here, the control of the first and second inverters 22, 24 will be described. The ECU 50 first coordinates (3-phase-2-phase conversion) the phase currents Iu, Iv, Iw of the respective phases of the motor 20 into the currents Id, Iq of the d-axis and q-axis using the electric angle θe of the motor 20, and sets the current commands Id*, Iq* of the d-axis and q-axis based on the torque command Tm* of the motor 20. Next, the voltage commands Vd*, Vq* of the d-axis and q-axis are calculated by current feedback control to eliminate the difference between the current commands Id*, Iq* and the currents Id, Iq. Then, the voltage commands Vd*, Vq* of the d-axis and q-axis are coordinated (2-phase-3-phase conversion) into the voltage commands Vu*, Vv*, Vw* of the respective phases using the electric angle θe, and the voltage commands Vu*, Vv*, Vw* of the respective phases obtained are subjected to the dead time correction described later to calculate the corrected voltage commands Vuad*, Vvad*, Vwad* of the respective phases. Further, the PWM signals of the transistors T11 to T16, T21 to T26 of the first and second inverters 22, 24 are generated by comparison of the corrected voltage commands Vuad*, Vvad*, Vwad* of the respective phases with the carrier voltage (triangular wave voltage), and the switching control of the transistors T11 to T16, T21 to T26 is performed.

[0017] Next, the process of the operation of the electric vehicle 10, and in particular, the corrected voltage command calculation process of the voltage commands Vu*, Vv*, Vw* of the respective phases will be described. Figure 2 is a flowchart showing an example of the corrected voltage command calculation process repeatedly performed by the ECU 50.

[0018] When this routine is executed, the ECU 50 calculates the dead time-based correction value Vdtbs by Expression (1) using the dead time Dt of the switching of the transistors T11 to T16, T21 to T26 of the first and second inverters 22, 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 can each be a constant value or a variable value based on the rotational speed Nm of the motor 20 or the like.

[0019] Vdtbs = Dt · fc · (VH / 2) (1)

[0020] Next, the q-axis reference current phase θi in the dq coordinate system is calculated as the arctangent of the value obtained by dividing the q-axis current command Iq* by the d-axis current command Id* (step S110). Then, the basic current phase θdtbs for dead-time correction is calculated by subtracting 90 [deg] from the sum of the current phase θi and the electrical angle θe (step S120). Further, the basic current phase θdtbs, a value obtained by subtracting 120 [deg] from the basic current phase θdtbs, and a value obtained by subtracting 240 [deg] from the basic current phase θdtbs are respectively 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 cross zero from positive to negative at the current phases θudt, θvdt, and θwdt for dead-time correction of 0 [deg], and cross zero from negative to positive at the current phases θudt, θvdt, and θwdt for dead-time correction of 180 [deg].

[0021] When the current phases θudt, θvdt, and θwdt for dead-time correction of each phase are thus set, it is determined whether the current phase θudt for dead-time correction of the U phase is less than 180 [deg] (step S140). When it is determined that the current phase θudt for dead-time correction is less than 180 [deg], the dead-time basic correction value Vdtbs is set as the dead-time correction value Vudt (step S142). On the other hand, when it is determined that the current phase θudt for dead-time correction is 180 [deg] or more, a value obtained by multiplying the dead-time basic correction value Vdtbs by -1 is set as the dead-time correction value Vudt (step S144). Similarly, as for the V phase and the W phase, the dead-time basic correction value Vdtbs is set as the dead-time correction values Vvdt and Vwdt when the current phases θvdt and θwdt for dead-time correction are less than 180 [deg], and a value obtained by multiplying the dead-time basic correction value Vdtbs by -1 is set as the dead-time correction values Vvdt and Vwdt when the current phases θvdt and θwdt for dead-time correction are 180 [deg] or more (steps S150 to S154, S160 to S164). Then, the 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 the corrected voltage commands Vuad*, Vvad*, and Vwad* of each phase are calculated (step S170), and the routine ends.

[0022] Figure 3 is an explanatory diagram showing an example of the states of the phase currents Iu, Iv, and Iw of each phase of the motor 20. Figure 3(A) indicates the case of the embodiment, Figure 3 (B) indicates the case of the comparative example. In the embodiment and the comparative example, the torque command Tm* and the rotational speed Nm are the same. In the comparative example, the dead time correction is not performed. That is, in the comparative example, the PWM signals of the transistors T11 to T16, T21 to T26 of the first inverter 22 and the second inverter 24 are generated by comparison of the voltage commands Vu*, Vv*, Vw* of the respective phases with the carrier voltage (triangular wave voltage), and the switching control of the transistors T11 to T16, T21 to T26 is performed. In the comparative example, as shown in (B), the phase currents Iu, Iv, Iw of the respective phases are distorted around zero. In addition, it is known that the maximum value and the effective value of the zero sequence current (Iu + Iv + Iw) become large. In contrast, in the embodiment, as shown in (A), the distortion of the phase currents Iu, Iv, Iw of the respective phases around zero is suppressed. In addition, it is known that the maximum value and the effective value of the zero sequence current are suppressed. It is considered that this is because, in the comparative example, the zero sequence current of the electrical third order is made explicit due to the dead time of the switching of the transistors T11 to T16, T21 to T26, and in contrast, in the embodiment, the phenomenon of making the zero sequence current explicit is suppressed by the dead time correction. By suppressing the phenomenon of making the zero sequence current explicit, it is possible to suppress the deterioration of the heat generation and the power consumption (energy efficiency) of the motor 20, the first inverter 22, and the second inverter 24. Figure 3 (B) indicates the case of the comparative example. In the embodiment and the comparative example, the torque command Tm* and the rotational speed Nm are the same. In the comparative example, the dead time correction is not performed. That is, in the comparative example, the PWM signals of the transistors T11 to T16, T21 to T26 of the first inverter 22 and the second inverter 24 are generated by comparison of the voltage commands Vu*, Vv*, Vw* of the respective phases with the carrier voltage (triangular wave voltage), and the switching control of the transistors T11 to T16, T21 to T26 is performed. In the comparative example, as shown in (B), the phase currents Iu, Iv, Iw of the respective phases are distorted around zero. In addition, it is known that the maximum value and the effective value of the zero sequence current (Iu + Iv + Iw) become large. In contrast, in the embodiment, as shown in (A), the distortion of the phase currents Iu, Iv, Iw of the respective phases around zero is suppressed. In addition, it is known that the maximum value and the effective value of the zero sequence current are suppressed. It is considered that this is because, in the comparative example, the zero sequence current of the electrical third order is made explicit due to the dead time of the switching of the transistors T11 to T16, T21 to T26, and in contrast, in the embodiment, the phenomenon of making the zero sequence current explicit is suppressed by the dead time correction. By suppressing the phenomenon of making the zero sequence current explicit, it is possible to suppress the deterioration of the heat generation and the power consumption (energy efficiency) of the motor 20, the first inverter 22, and the second inverter 24. Figure 3 (B) indicates the case of the comparative example. In the embodiment and the comparative example, the torque command Tm* and the rotational speed Nm are the same. In the comparative example, the dead time correction is not performed. That is, in the comparative example, the PWM signals of the transistors T11 to T16, T21 to T26 of the first inverter 22 and the second inverter 24 are generated by comparison of the voltage commands Vu*, Vv*, Vw* of the respective phases with the carrier voltage (triangular wave voltage), and the switching control of the transistors T11 to T16, T21 to T26 is performed. In the comparative example, as shown in (B), the phase currents Iu, Iv, Iw of the respective phases are distorted around zero. In addition, it is known that the maximum value and the effective value of the zero sequence current (Iu + Iv + Iw) become large. In contrast, in the embodiment, as shown in (A), the distortion of the phase currents Iu, Iv, Iw of the respective phases around zero is suppressed. In addition, it is known that the maximum value and the effective value of the zero sequence current are suppressed. It is considered that this is because, in the comparative example, the zero sequence current of the electrical third order is made explicit due to the dead time of the switching of the transistors T11 to T16, T21 to T26, and in contrast, in the embodiment, the phenomenon of making the zero sequence current explicit is suppressed by the dead time correction. By suppressing the phenomenon of making the zero sequence current explicit, it is possible to suppress the deterioration of the heat generation and the power consumption (energy efficiency) of the motor 20, the first inverter 22, and the second inverter 24.

[0023] In the drive device mounted on the electric vehicle 10 of the embodiment described above, the current phase θudt, θvdt, θwdt for the dead time correction of the respective phases is set on the basis of the current phase θi of the current commands Id*, Iq* of the d-axis and the q-axis and the electrical angle θe of the motor 20, the dead time correction value Vudt, Vvdt, Vwdt of the respective phases is set on the basis of the magnitude relation of the current phase θudt, θvdt, θwdt for the dead time correction of the respective phases and 180 [deg] (the phase of the phase current being zero), the voltage command Vu*, Vv*, Vw* of the respective phases is corrected using the dead time correction value Vudt, Vvdt, Vwdt of the respective phases to set the corrected voltage command Vuad*, Vvad*, Vwad* of the respective phases, and the switching control of the transistors T11 to T16, T21 to T26 of the first and second inverters 22, 24 is performed using the corrected voltage command Vuad*, Vvad*, Vwad* of the respective phases. Thereby, it is possible to suppress the phenomenon of making the zero sequence current explicit due to the dead time of the switching of the transistors T11 to T16, T21 to T26, and it is possible to suppress the deterioration of the heat generation and the power consumption (energy efficiency) of the motor 20, the first inverter 22, and the second inverter 24.

[0024] In the above-described embodiment, the configuration is provided in which the drive device is mounted on the electric vehicle 10 provided with the motor 20, but is not limited thereto. For example, the configuration can be provided in which the drive device is mounted on a hybrid vehicle provided with an engine in addition to the motor, or a fuel cell vehicle provided with a fuel cell in addition to the motor. In addition, the configuration can be provided in which the drive device is mounted on a mobile body other than a vehicle, or a construction equipment that does not move.

[0025] 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 will be described. In the embodiment, the battery 26 corresponds to the "electric power storage device", the motor 20 corresponds to the "motor", the first inverter 22 and the second inverter 24 correspond to the "first inverter and the second inverter", and the ECU 50 corresponds to the "control device".

[0026] Note that 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 an example of a specific description of the embodiment for implementing the invention described in the column of means for solving the problem, and thus does not limit the elements of the invention described in the column of means for solving the problem. That is, the explanation 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 embodiment is only a specific example of the invention described in the column of means for solving the problem.

[0027] The above describes the manner in which the present disclosure is implemented by using the embodiment, but the present disclosure is not limited to such an embodiment at all, and of course can be implemented in various ways without departing from the spirit of the present disclosure.

[0028] [Industrial applicability]

[0029] The present disclosure can be used in the manufacturing industry of drive devices and the like.

Claims

1. A drive apparatus comprising: an electric power storage device; a motor having a three-phase coil; a first inverter connected to a power line to which the electric power storage device is connected and connected to one end side of the three-phase coil, the first inverter having a plurality of first switching elements; a second inverter connected to the power line and connected to the other end side of the three-phase coil, the second inverter having a plurality of second switching elements; and a control device that sets current commands for d- and q-axes based on a torque command of the motor, sets voltage commands for phases based on the current commands for the d- and q-axes, and controls the first and second inverters using the voltage commands for the phases, wherein the control device sets current phases for dead-time correction for the phases based on the current commands for the d- and q-axes and an electric angle of the motor, sets positive or negative dead-time correction values for the phases based on a relationship between the current phases for dead-time correction for the phases and phases of zero phase currents, sets corrected voltage commands for the phases by correcting the voltage commands for the phases using the dead-time correction values for the phases, and controls the first and second inverters using the corrected voltage commands for the phases. ​ ​ ​ ​ ​ ​ ​ ​

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