Drive device

Abstract

The invention provides a driving device capable of suppressing the rotation of a motor and discharging the charge of a capacitor even if the rotation position of the motor is unknown. The drive device includes: a motor having a three-phase open winding; a first inverter which is connected to the power line, is connected to one end side of the three-phase open winding, and has a three-phase first upper arm and a three-phase first lower arm; a second inverter connected to the power line, connected to the other end side of the three-phase open winding, and having a second three-phase upper arm and a second three-phase lower arm; a capacitor connected to the power line; and a control device. When the charge of the capacitor is discharged, 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.

Description

Technical Field

[0001] This disclosure relates to drive devices. Background Technology

[0002] Previously, there have been technologies in which, in a vehicle that includes a motor, an inverter that drives the motor, and a capacitor connected to the power line of the inverter, in the event of a vehicle collision, the inverter is switched on in such a way that the d-axis current flows to the motor instead of the q-axis current, thereby discharging the charge of the capacitor (for example, see Patent Document 1).

[0003] Patent Document 1: Japanese Patent No. 6439726

[0004] In the aforementioned drive device, when the rotational position sensor malfunctions and the motor's rotational position cannot be detected, it is difficult to prevent the q-axis current from flowing to the motor and instead allow the d-axis current to flow to the motor, making it difficult to suppress motor rotation and discharge the capacitor's charge. In a drive device comprising a motor with a three-phase open-circuit winding, a first inverter connected to the power line and to one end of the three-phase open-circuit winding, a second inverter connected to the power line and to the other end of the three-phase open-circuit winding, and a capacitor connected to the power line, it is required that motor rotation be suppressed and the capacitor's charge be discharged even when the motor's rotational position is unknown. The main objective of the drive device disclosed herein is to suppress motor rotation and discharge the capacitor's charge even when the motor's rotational position is unknown. Summary of the Invention

[0005] To achieve the aforementioned main objectives, the drive device of this disclosure employs the following means. The drive device of this disclosure includes: a motor having a three-phase open-circuit winding; a first inverter connected to a power line and connected to one end of the three-phase open-circuit winding, having a first upper arm and a first lower arm of three phases; a second inverter connected to the power line and connected to the other end of the three-phase open-circuit winding, 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 purpose of which is that, when discharging the charge of the capacitor, the control device either connects the first upper arm and the second lower arm of a specified phase of the three phases, or connects the first lower arm and the second upper arm of a specified phase. In the drive device of this disclosure, through such control, even when the rotational position of the motor is unknown, the rotation of the motor can be suppressed and the charge of the capacitor can be discharged. Attached Figure Description

[0006] Figure 1 This is a simplified configuration diagram of an electric vehicle 10 equipped with a drive device according to the embodiment.

[0007] Figure 2 This is an explanatory diagram illustrating an example of sequence A when the main relay 14 of the system is disconnected, causing the charge of capacitors 30 and 32 to discharge.

[0008] Figure 3 This is an explanatory diagram illustrating an example of sequence B when the main relay 14 of the system is disconnected, causing the charge of capacitors 30 and 32 to discharge.

[0009] Explanation of reference numerals in the attached figures

[0010] 10… Electric vehicle; 12… Battery; 12i, 20u, 20v, 20w… Current sensors; 12v, 30v, 32v… Voltage sensors; 14… System main relay; 20… Motor; 20a… Rotary 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~D16, D21~D26… Diodes; T11~T16, T21~T26… Transistors. Detailed Implementation

[0011] The embodiments (implementations) for carrying out this disclosure will be described with reference to the accompanying drawings. Figure 1 This is a simplified configuration diagram of an electric vehicle 10 equipped with a drive device according to an embodiment of the present disclosure. As shown, the electric vehicle 10 of the embodiment includes a battery 12 as an energy storage device, a system main relay 14, a motor 20, first and second inverters 22 and 24, power lines 28 (positive line 28p and negative line 28n), capacitors 30 and 32, switches 34p and 34n, and an electronic control unit (hereinafter referred to as "ECU") 50 as a control device.

[0012] Battery 12 is configured as, for example, a lithium-ion secondary battery or a nickel-metal hydride secondary battery. The system main relay 14 connects and disconnects the positive and negative terminals of battery 12 from the positive line 28p and the negative line 28n. Motor 20 is configured as a three-phase AC motor, comprising a rotor with permanent magnets embedded in its rotor core and a stator with three-phase (U-phase, V-phase, W-phase) coils (open-circuit windings) wound in its stator core. The rotor is connected to a drive shaft via a differential gear to the drive wheel.

[0013] The first and second inverters 22 and 24 each have six transistors T11-T16 and T21-T26 as switching elements, and six diodes D11-D16 and D21-D26 connected in parallel with the six transistors T11-T16 and T21-T26, respectively. Transistors T11-T16 and T21-T26 may be, for example, Nch-MOSFETs or IGBTs. Transistors T11-T16 and T21-T26 are arranged in pairs, with the positive line 28p and negative line 28n as the source and drain sides, respectively. The connection points of the pairs of transistors T11-T16 are connected to one end of the coils of the three phases of the motor 20. The connection points of the pairs of transistors T21-T26 are connected to the other end of the coils of the three phases of the motor 20. Hereinafter, transistors T11 to T13 are sometimes referred to as the "first upper arm", transistors T14 to T16 as the "first lower arm", transistors T21 to T23 as the "second upper arm", and transistors T24 to T26 as the "second lower arm".

[0014] Capacitors 30 and 32 are connected near the first inverters 22 and 24 in power line 28, respectively. In this embodiment, in power line 28, from... Figure 1 Starting from the left side, the battery 12, capacitor 30, first inverter 22, second inverter 24, and capacitor 32 are connected in sequence. Switches 34p and 34n are respectively located between the first inverter 22 and the second inverter 22 in the positive line 28p and the negative line 28n.

[0015] ECU50 is equipped with a microcomputer featuring a CPU, ROM, RAM, flash memory, input / output ports, and communication ports, as well as various drive circuits and logic ICs. Signals from various sensors are input to ECU50. For example, inputs include the voltage Vb of battery 12 from voltage sensor 12V and the current Ib of battery 12 from current sensor 12i. Also inputs include the rotor rotational position θm of motor 20 from rotational position sensor 20a, and the phase currents Iu, Iv, and Iw of each phase of motor 20 from current sensors 20u, 20V, and 20W. Also inputs include the voltage VH of capacitor 30 from voltage sensor 30V and the voltage VL of capacitor 32 from voltage sensor 32V. Inputs also include on / off signals from the power switch, the gear lever operating position (gear SP) from the gear position sensor, the accelerator pedal depressor position (accelerator opening Acc) from the accelerator pedal position sensor, the brake pedal depressor position (brake pedal position BP) from the brake pedal position sensor, and the vehicle speed V from the vehicle speed sensor. Various control signals are output from ECU 50. For example, control signals are output to the system main relay 14, to transistors T11-T16 of the first inverter 22, to transistors T21-T26 of the second inverter 24, and to switches 34p and 34n. ECU 50 calculates the electrical angle θe and rotational speed Nm of motor 20 based on the rotor's rotational position θm, and calculates the state of charge (SOC) of battery 12 based on the accumulated current Ib of battery 12. The drive device in this embodiment mainly includes motor 20, first and second inverters 22 and 24, capacitors 30 and 32, and ECU 50.

[0016] In the electric vehicle 10 of the embodiment, the ECU 50 sets the required torque Td* for driving based on the accelerator opening Acc and the vehicle speed V, sets the torque command Tm* of the motor 20 in a manner that drives the vehicle according to the set required torque Td*, and controls the first and second inverters 22 and 24 and the switches 34p and 34n in a manner that drives the motor 20 by the set torque command Tm*.

[0017] Next, the operation of the electric vehicle 10 according to the embodiment, especially the operation when the main relay 14 of the system is disconnected and the charge of capacitors 30 and 32 is discharged during a vehicle collision, will be described. Figure 2 This is an illustrative diagram representing an example of sequence A at this point. In Figure 2In this process, switches 34p and 34n are turned on, and the sequence A1 to A4 is executed the necessary number of times until the voltage VH of capacitor 30 reaches below the threshold VHref. In sequence A1, the first upper arm (transistors T11 to T13) and the second lower arm (transistors T24 to T26) of the three phases are turned on, and the first lower arm (transistors T14 to T16) and the second upper arm (transistors T21 to T23) of the three phases are turned off. In this case, current flows from capacitors 30 and 32 to the positive line 28p, the first upper arm of the three phases, the three-phase motor 20, the second lower arm of the three phases, and the negative line 28n, causing the charge of capacitors 30 and 32 to discharge. Since the current in each phase of motor 20 flows in the same direction ( Figure 1 The current flows to the right without generating a rotating magnetic field in motor 20, thus suppressing the rotation of motor 20. Since the rotational position θm (electric angle θe) of the rotor of motor 20 is not used, the rotation of motor 20 can be suppressed even if the rotational position θm is unknown, such as when the rotational position sensor 20a malfunctions, and the charge of capacitors 30 and 32 is discharged. In sequence A2, the first upper arm and the second upper arm of the three phases are connected, and the first lower arm and the second lower arm of the three phases are disconnected. In this case, the current circulates in the path of the first upper arm of the three phases, the three-phase motor 20, the third upper arm of the three phases, and the positive line 28p. This is done to suppress the boost operation of motor 20 and the second inverter 24. Sequence A3 is the same as sequence A1. In sequence A4, the first lower arm and the second lower arm of the three phases are connected, and the first upper arm and the second upper arm of the three phases are disconnected. In this case, the current circulates in the path of the first lower arm of the three phases, the three-phase motor 20, the third lower arm of the three phases, and the negative line 28n. This is for the same reason as sequence A2, which is to suppress the temperature rise of the first upper arm of phase 3. In addition, sequence A1 can be executed alone, or a combination of sequences A1 and A2 can be executed as required, or a combination of sequences A1 and A4 can be executed as required.

[0018] In the drive unit of the electric vehicle 10 described above, when the system main relay 14 is disconnected to discharge the charge of capacitors 30 and 32, the first upper arm (transistors T11-T13) and the second lower arm (transistors T24-T26) of the three phases are connected, and the first lower arm (transistors T14-T16) and the second upper arm (transistors T21-T23) of the three phases are disconnected. Therefore, even when the rotational position θm of the rotor of motor 20 is unknown, the rotation of motor 20 can be suppressed, and the charge of capacitors 30 and 32 can be discharged.

[0019] In the above embodiment, when the system main relay 14 is disconnected to discharge the charge of capacitors 30 and 32, the following actions are performed: Figure 2The sequence A shown is (sequences A1 to A4), but it is not limited to this. For example, at this time, it is also possible to execute... Figure 3 The illustrated sequence B (sequences B1 to B2) is as follows: In sequence B1, similar to sequence A1, the first upper arm and second lower arm of the three phases are connected, and the first lower arm and second upper arm of the three phases are disconnected. In sequence B2, the first lower arm and second upper arm of the three phases are connected, and the first upper arm and second lower arm of the three phases are disconnected. In this case, current flows through the path from capacitors 30 and 32 to the positive line 28p, the second upper arm of the three phases, the three-phase motor 20, the first lower arm of the three phases, and the negative line 28n, causing the charge on capacitors 30 and 32 to discharge. Therefore, similar to sequence B1 (A1), even when the rotational position θm of the rotor of motor 20 is unknown, the rotation of motor 20 can be suppressed, and the charge on capacitors 30 and 32 can be discharged. Preferably, sequences B1 and B2 are executed at the same time.

[0020] In the above embodiment, when the system main relay 14 is disconnected to discharge the charge of capacitors 30 and 32, the following actions are performed: Figure 2 The sequence A shown is (sequences A1 to A4), but it is not limited to this. For example, at least one of sequences A1 and A3 can be replaced with sequence B2.

[0021] In the above embodiment, when the system main relay 14 is disconnected to discharge the charge of capacitors 30 and 32, current in the first orientation (from the first inverter 22 to the second inverter 24) flows through all three phases of motor 20 via sequence A1 (A3 and B1 are also the same), and current in the second orientation (from the second inverter 24 to the first inverter) flows through all three phases of motor 20 via sequence B2, but this is not a limitation. For example, current in the first orientation or the second orientation may flow only in one phase (e.g., phase U) of motor 20, or current in the same orientation may flow in two phases (e.g., phase U and phase V) of motor 20. Alternatively, current in the first orientation may flow through one phase (e.g., phase U) of motor 20, and current in the second orientation may flow through another phase (e.g., phase V).

[0022] In the above-described embodiment, when the system main relay 14 is disconnected to discharge the charge of capacitors 30 and 32, switches 34p and 34n are turned on, and sequences A1 (B1) and B2 are executed, but this is not a limitation. For example, one of switches 34p and 34n may be disconnected. When switch 34p is disconnected, the charge of capacitor 30 may be discharged via sequence A1, and the charge of capacitor 32 may be discharged via sequence B2. When switch 34n is disconnected, the charge of capacitor 32 may be discharged via sequence A1, and the charge of capacitor 30 may be discharged via sequence B2. When one of switches 34p and 34n is disconnected, the first upper arm and the second lower arm may be turned on for one phase (e.g., U phase) of motor 20, and the first lower arm and the second upper arm may be turned off, while the first lower arm and the second upper arm may be turned on for the other phase (e.g., V phase), and the first upper arm and the second lower arm may be turned off. In this way, the charges of capacitors 30 and 32 can be discharged in parallel.

[0023] Even if a short-circuit or open-circuit fault occurs in any of the transistors T11-T16 and T21-T26 in the first and second inverters 22 and 24, the charge of capacitors 30 and 32 can be discharged by using any of the methods described in the above embodiments. When a short-circuit fault occurs in any of the transistors T11-T13 and T24-T26, or when an open-circuit fault occurs in any of the transistors T14-T16 and T21-T23, the charge of capacitors 30 and 32 can be discharged, for example, via sequence A1 (B1). Furthermore, when a short-circuit fault occurs in any of the transistors T14-T16 and T21-T23, or when an open-circuit fault occurs in any of the transistors T11-T13 and T24-T26, the charge of capacitors 30 and 32 can be discharged, for example, via sequence B2.

[0024] In the above-described embodiments, the electric vehicle 10 includes a motor 20, first and second inverters 22 and 24, capacitors 30 and 32, and switches 34p and 34n, but is not limited thereto. For example, one of the capacitors 30 and 32 may be omitted. Additionally, at least one of the switches 34p and 34n may be omitted.

[0025] In the above embodiment, it is configured to be installed in the drive unit of an electric vehicle 10 equipped with a motor 20, but it is not limited to this. For example, it can also be configured to be installed in the drive unit of a hybrid vehicle that has an engine in addition to a motor. Alternatively, it can be configured to be installed in the drive unit of a fuel cell vehicle that has a fuel cell in addition to a motor.

[0026] The main elements of the implementation method and their correspondence with the main elements of the invention described in the means for solving the problem section will be explained. In the implementation method, motor 20 is equivalent to "motor", first inverter 22 is equivalent to "first inverter", second inverter 24 is equivalent to "second inverter", capacitors 30 and 32 are equivalent to "capacitors", and ECU 50 is equivalent to "control device".

[0027] Furthermore, the correspondence between the main elements of the implementation method and the main elements of the invention described in the "Means for Solving the Problem" column is merely an example used to specifically explain the manner in which the invention described in the "Means for Solving the Problem" column is implemented in the implementation method, and therefore is not limited to the elements of the invention described in the "Means for Solving the Problem" column. That is, the interpretation of the invention described in the "Means for Solving the Problem" column should be based on the description in that column, and the implementation method is merely a specific example of the invention described in the "Means for Solving the Problem" column.

[0028] The above describes the methods for implementing this disclosure using the embodiments, but this disclosure is not limited to such embodiments. Of course, it can be implemented in various ways without departing from the spirit of this disclosure.

[0029] [Industrial Availability]

[0030] This disclosure can be used in industries such as the manufacturing of drive devices.

Claims

1. A drive device comprising: a motor having a three-phase open-circuit winding; a first inverter connected to a power line and connected to one end of the three-phase open-circuit winding, and having a three-phase first upper arm and a first lower arm; a second inverter connected to the power line and connected to the other end of the three-phase open-circuit winding, and having a three-phase second upper arm and a second lower arm; a capacitor connected to the power line; and a control device. Its features are, When discharging the capacitor, the control device connects the first upper arm and the second lower arm of a specified phase in the three phases, or connects the first lower arm and the second upper arm of the specified phase.

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