Drive device

Abstract

The invention relates to a driving device for further increasing heat production. The drive device is provided with a control device that controls the first inverter and the second inverter on the basis of a torque command of the motor, the control device uses all phase currents of three phases of a three-phase coil of the motor to pass through the power line and the first inverter from one of the first inverter and the second inverter. The first inverter and the second inverter are controlled so that the other of the second inverters circulates to three phases and the amounts of current of the positive and negative lines of the power line are different.

Description

Technical Field

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

[0002] Conventionally, drive devices comprising a motor, an inverter, and a hydraulic mechanism have been proposed (see, for example, Patent Document 1). The motor has two rotors. The hydraulic mechanism supplies working oil to a phase-changing mechanism mounted on the rotors of the motor. In this device, when the temperature of the working oil is below a predetermined temperature, the stator coils of the motor are energized to heat the working oil. This improves the responsiveness of phase changes at low temperatures.

[0003] Patent Document 1: Japanese Patent Application Publication No. 2009-44805

[0004] In addition, a drive device is proposed, comprising: an energy storage device; a motor having three-phase coils; and a first inverter and a second inverter connected to a power line connected to the energy storage device and connected to one end and the other end of the three-phase coils, and having multiple first switching elements and second switching elements. Thus, in a drive device where the first inverter, the second inverter, and the motor are connected via an H-connection, further increasing the heat generation of the motor, the first inverter, and the second inverter in order to heat the energy storage device is identified as an important issue. Summary of the Invention

[0005] The main purpose of the drive device disclosed herein is to further increase heat generation.

[0006] The drive device disclosed herein employs the following mechanism to achieve the aforementioned main objective. The drive device of this disclosure includes: an energy storage device; a motor having three-phase coils; a first inverter connected to a power line connected to the energy storage device and to one end of the three-phase coils, having a plurality of first switching elements; a second inverter connected to the power line and to the other end of the three-phase coils, having a plurality of second switching elements; a cooling device using a cooling medium to cool the energy storage device, the motor, the first inverter, and the second inverter; and a control device that controls the first inverter and the second inverter based on torque commands from the motor, wherein the control device controls the first inverter and the second inverter in such a manner that all phase currents of the three phases of the motor's three-phase coils circulate from one of the first inverters and the second inverter through the power line and the other of the first inverters and the second inverter to the three phases, and the current amounts on the positive and negative terminals of the power line are different values. In the drive device disclosed herein, such a structure allows for a further increase in the heat generation of the motor, the first inverter, and the second inverter. Attached Figure Description

[0007] Figure 1 This is a simplified configuration diagram of an electric vehicle equipped with a drive device according to an embodiment of the present disclosure.

[0008] Figure 2 This is a block diagram representing an example of a function block in the control of the first and second inverters of the ECU at low temperatures.

[0009] Figure 3 This is an explanatory diagram illustrating an example of the flow of current in an electric vehicle according to an embodiment. Detailed Implementation

[0010] 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 motor 20, a first converter 22, a second converter 24, a battery 26 as an energy storage device, switching devices 32, 32 as load devices, a cooling device 40, and an electronic control unit (hereinafter referred to as "ECU") 50 as a control device.

[0011] Motor 20 is configured, for example, as a three-phase AC motor, which has: a rotor in which permanent magnets are embedded in the rotor core; and a stator in which three-phase (U-phase, V-phase, W-phase) coils are wound in the stator core. The rotor is connected to a drive shaft that is connected to a drive wheel via a differential gear.

[0012] The first inverter 22 and the second inverter 24 are respectively connected to the power line 28 (positive line 28p and negative line 28n) connected to the battery 26, and are also connected to one end and the other end of the three-phase coil of the motor 20. The first inverter 22 includes six transistors (first switching elements) T11 to T16 as switching elements and six diodes D11 to D16 connected in parallel with each of the six transistors T11 to T16. Transistors T11 to T16 are arranged in pairs, with the positive line 28p and the negative line 28n as the source and sink sides, respectively. Each connection point of the pair of transistors T11 to T16 is connected to one end of the three-phase coil of the motor 20. The second inverter 24, like the first inverter 22, includes six transistors (second switching elements) T21 to T26 as switching elements and six diodes D21 to D26. Transistors T21 to T26 are arranged in pairs, with the positive line 28p and the negative line 28n as the source and drain sides, respectively. Each connection point of the pair of transistors T21 to T26 is connected to the other end of the three-phase coil of the motor 20. The battery 26, for example, is configured as a lithium-ion secondary battery or a nickel-metal hydride secondary battery, and is connected to the 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 battery 26, the capacitor 30, the first inverter 22, and the second inverter 24 are sequentially connected to the power line 28.

[0013] The switching device 32 is installed on the positive terminal 28p of the power line 28. The switching device 32 includes two transistors T31 and T32 and two diodes D31 and D32. Transistors T31 and T32 are connected in series on the positive terminal 28p.

[0014] Diode D31 is connected in parallel with transistor T31 in a forward-biased manner from the first inverter 22 toward the second inverter 24. Diode D32 is connected in parallel with transistor T32 in a forward-biased manner from the second inverter 24 toward the first inverter 22. Switching device 33 is mounted on the negative line 28n of power line 28. Switching device 33 includes transistor T32 and diode D33. Transistors T31 and T33 are connected in series on the negative line 28n. Diode D33 is connected in parallel with transistor T33 in a forward-biased manner from the first inverter 22 toward the second inverter 24.

[0015] The cooling device 40 includes a circulation path 42, a radiator 44, and an electric pump 46. The circulation path 42 is configured to circulate a cooling medium, such as cooling water, sequentially to the battery 26, the first inverter 22, the motor 20, the second inverter 24, and the radiator 44. The electric pump 46 circulates the cooling medium in the circulation path 42. Alternatively, the circulation path 42 may also be configured to circulate the cooling medium sequentially to the second inverter 24, the motor 20, the first inverter 22, the battery 26, and the radiator 44.

[0016] The ECU50 is equipped with a microcomputer containing 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 the ECU50. The input signals include, for example, the rotational position θm of the rotational position sensor 20a which detects the rotational position of the rotor of the motor 20, the phase currents Iu, Iv, and Iw of the motor 20 which detect the phase currents of each phase of the motor 20, the voltage Vb of the battery 26 which is detected by the voltage sensor 26v, the current Ib of the battery 26 which is detected by the current sensor 26i, the temperature Tb of the battery 26 which is detected by the temperature sensor 26t, the voltage VH of the capacitor 30 (power line 28) which is detected by the voltage sensor 30v, the on / off signal from the power switch 60, the operating position (gear SP) of the shift lever 61 which is detected by the gear position sensor 62, the amount of pressure applied to the accelerator pedal 63 which is detected by the accelerator pedal position sensor 64 (accelerator opening Acc), the amount of pressure applied to the brake pedal 65 which is detected by the brake pedal position sensor 66 (brake pedal position BP), and the vehicle speed V which is detected by the vehicle speed sensor 67. The ECU 50 outputs switching control signals for transistors T11-T16 and T21-T26 of the first inverter 22 and the second inverter 24, and switching control signals for transistors T31 and T32 of the switching device 32. The ECU 50 calculates the electrical angle θe and rotational speed Nm of the motor 20 based on the rotor's rotational position θm, or calculates the state of charge (SOC) of the battery 26 based on the accumulated current Ib of the battery 26.

[0017] 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 the manner of driving by the set required torque Td*, and controls the switching of transistors T11 to T16 and T21 to T26 of the first converter and the second converter 22 and 24 based on the set torque command Tm*.

[0018] Next, the operation of the electric vehicle 10, especially the control of the first inverter 22 and the second inverter 24 at low temperatures, will be explained. Figure 2This is a block diagram illustrating an example of a function block in the control of the first inverter 22 and the second inverter 24 based on the ECU 50 at low temperatures. This function block is applied to the control of the phase current of the U phase, but the same function block can also be applied to the V and W phases. Here, "low temperature" can refer to situations where the external temperature is below a specified temperature (e.g., 1°C, 3°C, 5°C, etc.), or when the battery 26 is at a low temperature where it cannot function. Furthermore, when the transistors T31, T32, and T33 of the switching devices 32 and 33 are turned on, the electric vehicle 10 stops. The ECU 50 includes a current command setting unit 500, a feedback (FB) correction setting unit 510, and a PWM signal generation unit 520 as... Figure 2 Functional blocks.

[0019] The current command setting unit 500 sets the current command Iu* of the motor 20 based on one-third of the required heat Qreq for the battery 26 to heat up, and outputs the set current command Iu*. The ECU 50 pre-determines the relationship between the difference between the current temperature Tb of the battery 26 from the temperature sensor 26t and the lower limit of the temperature range in which the battery 26 can perform, and the required heat Qreq through experiments, analysis, machine learning, etc., and stores this relationship in ROM. The required heat Qreq is set based on this relationship and the difference between the temperature Tb of the battery 26 from the temperature sensor 26t and the lower limit of the temperature range in which the battery 26 can perform. The current command setting unit 500 sets the current command Iu* within a range not exceeding one-third of the maximum allowable current Immax of the motor 20 and one-third of the maximum allowable current Invmax of the first inverter 22 and the second inverter 24, such that it increases when the required heat Qreq is large compared to when the required heat Qreq is small.

[0020] The FB correction setting unit 510 receives the difference between the input current command Iu* and the phase current Iu of each phase of the motor 20 from the current sensor 22u, sets a feedback correction term Dfbu for the duty cycle command D* used to eliminate the difference between the current command Iu* and the phase current Iu, and outputs the set feedback correction term Dfbu. Here, the duty cycle command D* is the proportion of the on-time of each transistor in one cycle (the sum of the on-time and off-time of each transistor).

[0021] The PWM signal generation unit 520 receives a duty cycle command Du1* for the first inverter 22, obtained by adding a predetermined basic value Db of the duty cycle command to a feedback correction term Dfbu, and a duty cycle command Du2* for the second inverter 24, obtained by adding the basic value Db to the feedback correction term Dfbu multiplied by a value minus 1. By comparing the duty cycle commands Du1* and Du2* with a triangular wave (carrier wave), a U-phase PWM signal for switching transistors T11, T14, T21, and T24 in the first inverter 22 and the second inverter 24 is generated. The generated PWM signal is then output to the first inverter 22 and the second inverter 24 to control the switching of transistors T11, T14, T21, and T24 in the first inverter 22 and the second inverter 24. Here, the basic value Db of the duty cycle command is preset to a value different from 50%. The reason for setting the basic value Db to a value different from 50% will be explained later. Using the same method described above, PWM signals for the V and W phases of transistors T12, T13, T15, T16, T22, T23, T25, and T26 in the first inverter 22 and the second inverter 24 are generated and output to control the switching of transistors T12, T13, T15, T16, T22, T23, T25, and T26 in the first inverter 22 and the second inverter 24. This control provides feedback control for the first and second inverters 22 and 24, ensuring that the phase currents Iu, Iv, and Iw of each phase of the motor 20 are current quantities based on the required heat Qreq.

[0022] Figure 3 This is an explanatory diagram illustrating an example of current flow in an electric vehicle 10 according to an embodiment. Figure 3 In the diagram, the thick arrow indicates the direction of the current. In this embodiment, the first inverter 22 and the second inverter 24 are controlled such that the phase currents Iu, Iv, and Iw of each phase of the motor 20 flow in the direction from the first inverter 22 towards the second inverter 24 and become the same current value. Through such control, as... Figure 3 As shown, current flows from each phase of motor 20 through the second inverter 24 to the positive line 28p (switching device 32) and negative line 28n (switching device 33) of power line 28, and then circulates to each phase through the first inverter 22. Thus, the heat generated by motor 20, first inverter 22, second inverter 24, and switching devices 32 and 33 is used to promote the heating of the cooling medium in cooling device 40, thereby promoting the heating of battery 26. This further suppresses the deterioration of battery 26 caused by low temperature.

[0023] Here, the reason why the basic value Db is set to a value different from 50% will be explained. If the basic value Db is set to a value different from 50%, the current flowing through the positive line 28p and the current flowing through the negative line 28n will become different. For example, when the basic value Db exceeds 50% and the phase currents Iu, Iv, and Iw are the same, the current I0n flowing through the negative line 28n is less than the current I0p flowing through the positive line 28p. When the maximum current allowed by the transistor T33 of the switching device 33 is less than the maximum current allowed by the transistors T31 and T32 of the switching device 32, if the current I0p of the positive line 28p is made the same as the current I0n of the negative line 28n, the current flowing exceeds the maximum current allowed by the transistor T33 of the switching device 33, and sometimes the protection of the transistor T33 cannot be achieved. In this situation, by setting the basic value Db to a value exceeding 50%, the current I0n of the negative line 28n can be made less than the current I0p of the positive line 28p, thus protecting transistor T33. Furthermore, if the maximum allowable current of transistor T33 in switching device 33 is greater than the maximum allowable current of transistors T31 and T32 in switching device 32, and if the current I0p of the positive line 28p is the same as the current I0n of the negative line 28n, then current flowing exceeding the maximum allowable current of transistors T31 and T32 in switching device 32 may sometimes fail to protect transistors T31 and T32. In this case, by setting the basic value Db to a value less than 50%, the current I0p of the positive line 28p can be made less than the current I0n of the negative line 28n, thus protecting transistors T31 and T32. Thus, by setting the basic value Db to a value different from 50%, protection can be achieved for transistors T31, T32, and T33.

[0024] In the electric vehicle 10 equipped with the drive device of the above-described embodiment, the first inverter 22 and the second inverter 24 are controlled in such a way that all the phase currents Iu, Iv, and Iw of the three phases of the three-phase coil of the motor 20 circulate from the first inverter 22 through the power line 28 and the second inverter 24 to the three phases, and the current amounts of the positive line 28p and the negative line 28n of the power line 28 are different values, thereby further increasing the heat generation.

[0025] In the above embodiment, the first inverter 22 and the second inverter 24 are controlled in such a way that all the phase currents Iu, Iv, and Iw of the three phases of the three-phase coil of the motor 20 circulate from the first inverter 22 through the power line 28 and the second inverter 24 to the three phases. However, the first inverter 22 and the second inverter 24 can also be controlled in such a way that the phase currents Iu, Iv, and Iw circulate from the second inverter 24 through the power line 28 and the first inverter 22 to the three phases.

[0026] In the above-described embodiment, switching devices 32 and 33 are provided on the power line 28. However, it is also possible to provide only one of the switching devices 32 and 33 on the power line 28, or not to provide such switching devices 32 and 33 at all.

[0027] In the above-described embodiment, it is mounted on the drive unit of an electric vehicle 10 equipped with a motor 20. However, it can also be mounted on the drive unit of a hybrid vehicle that is equipped with an engine in addition to a motor, on the drive unit of a fuel cell vehicle that is equipped with a fuel cell in addition to a motor, or on the drive unit of a mobile body other than a vehicle or a stationary construction device.

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

[0029] [Industrial Applicability]

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

[0031] Explanation of reference numerals in the attached figures

[0032] 22…First inverter; 24…Inverter; 50…Electronic control unit (ECU).

Claims

1. A driving device comprising: Energy storage devices; The motor has three-phase coils; The first inverter is connected to the power line connected to the energy storage device and to one end of the three-phase coil, and has a plurality of first switching elements; The second inverter, connected to the power line and to the other end of the three-phase coil, has a plurality of second switching elements; A cooling device that uses a cooling medium to cool the energy storage device, the motor, the first inverter, and the second inverter; as well as The control device controls the first inverter and the second inverter based on the torque command of the motor. in, The control device controls the first inverter and the second inverter in such a manner that all phase currents of the three phases of the motor's three-phase coils circulate from one of the first inverters and the second inverter through the power line and the other of the first inverters and the second inverter to the three phases, and the current amounts of the positive and negative lines of the power line are different values.

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