Drive device

Abstract

To discharge the electric charge of a capacitor while suppressing the rotation of a motor even when the rotational position of the motor is unknown.SOLUTION: The drive device includes a motor having a three-phase open winding, a first inverter connected to a power line and connected to one end side of the three-phase open winding and having three-phase first upper arms and first lower arms, a second inverter connected to the power line and connected to the other end side of the three-phase open winding and having three-phase second upper arms and second lower arms, a capacitor connected to the power line, and a control device. When discharging the electric charge of the capacitor, the control device turns on the first upper arm and the second lower arm of a predetermined phase among the three phases or turns on the first lower arm and the second upper arm of the predetermined phase.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] In a conventional vehicle equipped with a motor, an inverter that drives the motor, and a capacitor connected to a power line to which the inverter is connected, when a vehicle collision is detected, a system has been proposed in which the inverter is switched so as to pass a d-axis current through the motor without passing a q-axis current, thereby discharging the charge in the capacitor (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6439726 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-described drive device, when the rotational position of the motor cannot be detected, for example, when an abnormality occurs in the rotational position sensor that detects the rotational position of the motor, it is difficult to pass a d-axis current through the motor without passing a q-axis current, making it difficult to discharge the charge of the capacitor while suppressing motor rotation. In a drive device including a motor having a three-phase open winding, a first inverter connected to a power line and connected to one end of the three-phase open winding, a second inverter connected to the power line and connected to the other end of the three-phase open winding, and a capacitor connected to the power line, it is desired to be able to discharge the charge of the capacitor while suppressing motor rotation even when the rotational position of the motor is unknown. The main objective of the drive device disclosed herein is to be able to discharge the charge of the capacitor while suppressing motor rotation even when the rotational position of the motor is unknown. [Means for solving the problem]

[0005] The drive device of the present disclosure employs the following measures to achieve the above-mentioned primary object. The drive device of the present disclosure includes a motor having a three-phase open winding, a first inverter connected to a power line and connected to one end of the three-phase open winding and having a first upper arm and a first lower arm of the three phases, a second inverter connected to the power line and connected to the other end of the three-phase open winding and having a second upper arm and a second lower arm of the three phases, a capacitor connected to the power line, and a control device, wherein the control device turns on the first upper arm and the second lower arm of a predetermined phase among the three phases or turns on the first lower arm and the second upper arm of the predetermined phase when discharging the charge of the capacitor. With this control, the drive device of the present disclosure can discharge the charge of the capacitor while suppressing motor rotation even when the rotational position of the motor is unknown. [Brief explanation of the drawings]

[0006] [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 an explanatory diagram showing an example of a sequence A when the system main relay 14 is turned off to discharge the electric charges of the capacitors 30 and 32. FIG. [Figure 3] 10 is an explanatory diagram showing an example of a sequence B when the system main relay 14 is turned off to discharge the charges in the capacitors 30 and 32. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0007] 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 battery 12 as an electricity storage device, a system main relay 14, a motor 20, first and second inverters 22, 24, power lines 28 (positive line 28p and negative line 28n), capacitors 30, 32, switches 34p, 34n, and an electronic control unit (hereinafter referred to as "ECU") 50 as a control device.

[0008] Battery 12 is configured as, for example, a lithium-ion secondary battery or a nickel-metal hydride secondary battery. System main relay 14 connects and disconnects the positive and negative terminals of battery 12 to and from positive and negative lines 28p and 28n. Motor 20 is configured as a three-phase AC motor and includes a rotor with a permanent magnet embedded in a rotor core and a stator with three-phase (U-phase, V-phase, W-phase) coils (open windings) wound around a stator core. The rotor is connected to a drive shaft that is connected to drive wheels via a differential gear.

[0009] The first and second inverters 22 and 24 each include six transistors T11 to T16 and T21 to T26 as switching elements, and six diodes D11 to D16 and D21 to D26 connected in parallel to the six transistors T11 to T16 and T21 to T26, respectively. The transistors T11 to T16 and T21 to T26 may be, for example, Nch-MOSFETs or IGBTs. The transistors T11 to T16 and T21 to T26 are arranged in pairs, two at a time, on the source side and two at the sink side of the positive line 28p and the negative line 28n. The junctions of the paired transistors T11 to T16 are connected to one end of the three-phase coils of the motor 20. The junctions of the paired transistors T21 to T26 are connected to the other end of the three-phase coils of the motor 20. Hereinafter, each of the transistors T11 to T13 may be referred to as a "first upper arm," each of the transistors T14 to T16 as a "first lower arm," each of the transistors T21 to T23 as a "second upper arm," and each of the transistors T24 to T26 as a "second lower arm."

[0010] The capacitors 30 and 32 are connected to the power line 28 near the first inverters 22 and 24, respectively. In this embodiment, the battery 12, the capacitor 30, the first inverter 22, the second inverter 24, and the capacitor 32 are connected to the power line 28 in this order from the left side of FIG. 1. The switches 34p and 34n are provided between the first inverter 22 and the second inverter 22 on the positive line 28p and the negative line 28n, respectively.

[0011] 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. The ECU 50 receives signals from various sensors. For example, the voltage Vb of the battery 12 from a voltage sensor 12v and the current Ib of the battery 12 from a current sensor 12i are input. The ECU 50 also receives the rotational position θm of the rotor of the motor 20 from a rotational position sensor 20a and the phase currents Iu, Iv, and Iw of the motor 20 from current sensors 20u, 20v, and 20w. The ECU 50 also receives the voltage VH of the capacitor 30 from a voltage sensor 30v and the voltage VL of the capacitor 32 from a voltage sensor 32v. The ECU 50 also receives an on / off signal from a power switch, the operating position of the shift lever (shift position SP) from a shift position sensor, the accelerator pedal depression amount (accelerator opening Acc) from an accelerator pedal position sensor, the brake pedal depression amount (brake pedal position BP) from a brake pedal position sensor, and the vehicle speed V from a vehicle speed sensor. Various control signals are output from the ECU 50. For example, a control signal is output to the system main relay 14, control signals to the transistors T11 to T16 of the first inverter 22 and the transistors T21 to T26 of the second inverter 24, and control signals to the switches 34p and 34n. 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 state of charge (SOC) of the battery 12 based on the integrated value of the current Ib of the battery 12. The drive device of this embodiment mainly includes the motor 20, the first and second inverters 22 and 24, the capacitors 30 and 32, and the ECU 50.

[0012] In the electric vehicle 10 of this embodiment, the ECU 50 sets the required torque Td* required for driving based on the accelerator opening Acc and the vehicle speed V, sets the torque command Tm* for the motor 20 so that the vehicle drives at the set required torque Td*, and controls the first and second inverters 22, 24 and the switches 34p, 34n so that the motor 20 is driven at the set torque command Tm*.

[0013] Next, the operation of the electric vehicle 10 according to this embodiment will be described, particularly the operation performed when the system main relay 14 is turned off to discharge the charge in the capacitors 30 and 32 in the event of a vehicle collision or the like. FIG. 2 is an explanatory diagram showing an example of sequence A in this case. In FIG. 2, the switches 34p and 34n are turned on, and a set of sequences A1 to A4 is executed a necessary number of times until the voltage VH of the capacitor 30 falls below the threshold VHref. In sequence A1, the first three-phase upper arm (transistors T11 to T13) and the second three-phase lower arm (transistors T24 to T26) are turned on, and the first three-phase lower arm (transistors T14 to T16) and the second three-phase upper arm (transistors T21 to T23) are turned off. In this case, current flows from the capacitors 30 and 32 through the positive line 28p, the three-phase first upper arm, the three-phase motor 20, the three-phase second lower arm, and the negative line 28n, thereby discharging the charge in the capacitors 30 and 32. Because current flows in the same direction (to the right in FIG. 1 ) through each phase of the motor 20, no rotating magnetic field is generated in the motor 20, suppressing rotation of the motor 20. Because the rotational position θm (electrical angle θe) of the rotor of the motor 20 is not used, even if the rotational position θm is unknown, such as when an abnormality occurs in the rotational position sensor 20a, the charge in the capacitors 30 and 32 can be discharged while suppressing rotation of the motor 20. In sequence A2, the first and second upper arms for the three phases are turned on, and the first and second lower arms for the three phases are turned off. In this case, current circulates through the path of the first upper arm for the three phases, the three-phase motor 20, the second upper arm for the three phases, and the positive line 28p. This is performed to suppress the boost operation of the motor 20 and the second inverter 24. Sequence A3 is the same as sequence A1. In sequence A4, the first and second lower arms for the three phases are turned on, and the first and second upper arms for the three phases are turned off. In this case, current circulates through the path of the first three-phase lower arm, the three-phase motor 20, the second three-phase lower arm, and the negative line 28n. This is done for the same reason as sequence A2, and to suppress a temperature rise in the first three-phase upper arm. Note that only sequence A1 may be executed, or the set of sequences A1 and A2 may be executed a required number of times, or the set of sequences A1 and A4 may be executed a required number of times.

[0014] In the drive device mounted on the electric vehicle 10 of the embodiment described above, when the system main relay 14 is turned off to discharge the charge in the capacitors 30, 32, the first three-phase upper arm (transistors T11 to T13) and second three-phase lower arm (transistors T24 to T26) are turned on and the first three-phase lower arm (transistors T14 to T16) and second three-phase upper arm (transistors T21 to T23) are turned off. This makes it possible to discharge the charge in the capacitors 30, 32 while suppressing rotation of the motor 20, even if the rotational position θm of the rotor of the motor 20 is unknown.

[0015] In the above-described embodiment, sequence A (sequences A1 to A4) shown in FIG. 2 is executed when the system main relay 14 is turned off to discharge the charge of the capacitors 30 and 32. However, this is not limiting. For example, sequence B (sequences B1 to B2) shown in FIG. 3 may be executed at this time. In sequence B1, similar to sequence A1, the first upper arm and second lower arm of the three phases are turned on, and the first lower arm and second upper arm of the three phases are turned off. In sequence B2, the first lower arm and second upper arm of the three phases are turned on, and the first upper arm and second lower arm of the three phases are turned off. In this case, current flows from the capacitors 30 and 32 through the positive line 28p, the second upper arm of the three phase, the three-phase motor 20, the first lower arm of the three phase, and the negative line 28n, thereby discharging the charge of the capacitors 30 and 32. Therefore, similar to sequence B1 (A1), even if the rotational position θm of the rotor of motor 20 is unknown, the charges of capacitors 30, 32 can be discharged while suppressing the rotation of motor 20. Sequences B1 and B2 are preferably executed for the same period of time.

[0016] In the above-described embodiment, when the system main relay 14 is turned off to discharge the charge in the capacitors 30 and 32, sequence A (sequences A1 to A4) shown in Fig. 2 is executed, but this is not limiting. For example, at least one of sequences A1 and A3 may be replaced with sequence B2.

[0017] In the above-described embodiment, when the system main relay 14 is turned off to discharge the charge of the capacitors 30, 32, a current is passed through all three phases of the motor 20 in a first direction (from the first inverter 22 to the second inverter 24) according to sequence A1 (similarly to A3 and B1), or a current is passed through all three phases of the motor 20 in a second direction (from the second inverter 24 to the first inverter) according to sequence B2. However, the present invention is not limited to this. For example, a current in the first or second direction may be passed through only one phase (e.g., the U phase) of the motor 20, or currents in the same direction may be passed through two phases (e.g., the U phase and the V phase) of the motor 20. Alternatively, a current in the first direction may be passed through one phase (e.g., the U phase) of the motor 20, and a current in the second direction may be passed through another phase (e.g., the V phase) of the motor 20.

[0018] In the above-described embodiment, when the system main relay 14 is turned off to discharge the charge of the capacitors 30 and 32, the switches 34p and 34n are turned on and the sequence A1 (B1) or the sequence B2 is executed. However, this is not limiting. For example, one of the switches 34p and 34n may be turned off. When the switch 34p is turned off, the charge of the capacitor 30 may be discharged according to the sequence A1, and the charge of the capacitor 32 may be discharged according to the sequence B2. When the switch 34n is turned off, the charge of the capacitor 32 may be discharged according to the sequence A1, and the charge of the capacitor 30 may be discharged according to the sequence B2. When one of the switches 34p and 34n is turned off, the first upper arm and the second lower arm may be turned on and the first lower arm and the second upper arm may be turned off for one phase (e.g., U phase) of the motor 20, and the first lower arm and the second upper arm may be turned on and the first upper arm and the second lower arm may be turned off for another phase (e.g., V phase). In this way, the charges on the capacitors 30 and 32 can be discharged in parallel.

[0019] Even if a short circuit or an open circuit occurs in any of the transistors T11 to T16, T21 to T26 of the first and second inverters 22, 24, the charge in the capacitors 30, 32 can be discharged by using any of the methods of the above-described embodiments. If a short circuit occurs in any of the transistors T11 to T13, T24 to T26, or if an open circuit occurs in any of the transistors T14 to T16, T21 to T23, the charge in the capacitors 30, 32 can be discharged, for example, by sequence A1 (B1). Also, if a short circuit occurs in any of the transistors T14 to T16, T21 to T23, or if an open circuit occurs in any of the transistors T11 to T13, T24 to T26, the charge in the capacitors 30, 32 can be discharged, for example, by sequence B2.

[0020] In the above-described embodiment, the electric vehicle 10 includes the motor 20, the first and second inverters 22, 24, the capacitors 30, 32, and the switches 34p, 34n, but is not limited to this. For example, one of the capacitors 30, 32 may be omitted. Also, at least one of the switches 34p, 34n may be omitted.

[0021] In the above-described embodiment, the drive device is mounted on an electric vehicle 10 equipped with a motor 20, but is not limited to this. For example, the drive device may be mounted on a hybrid vehicle equipped with an engine in addition to a motor. Also, the drive device may be mounted on a fuel cell vehicle equipped with a fuel cell in addition to a motor.

[0022] 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 motor 20 corresponds to the "motor," the first inverter 22 corresponds to the "first inverter," the second inverter 24 corresponds to the "second inverter," the capacitors 30 and 32 correspond to the "capacitors," and the ECU 50 corresponds to the "controller."

[0023] 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.

[0024] 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]

[0025] The present disclosure is applicable to industries such as the drive device manufacturing industry. [Explanation of symbols]

[0026] 10 electric vehicle, 12 battery, 12i, 20u, 20v, 20w current sensors, 12v, 30v, 32v voltage sensors, 14 system main relay, 20 motor, 20a rotational position sensor, 22 first inverter, 24 second inverter, 28 power line, 28n negative line, 28p positive line, 30, 32 capacitors, 34n, 34p switches, 50 ECU, D11 to D16, D21 to D26 diodes, T11 to T16, T21 to T26 transistors.

Claims

[Claim 1] A drive device comprising: a motor having a three-phase open winding; a first inverter connected to a power line, connected to one end of the three-phase open winding, and having a first upper arm and a first lower arm of three phases; a second inverter connected to the power line, connected to the other end of the three-phase open winding, and having a second upper arm and a second lower arm of three phases; a capacitor connected to the power line; and a control device, the control device turns on the first upper arm and the second lower arm of a predetermined phase among the three phases or turns on the first lower arm and the second upper arm of the predetermined phase when discharging the charge of the capacitor. Drive unit.

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