Drive device

Abstract

To increase a heat generation amount.SOLUTION: A control device configured to control the first and second inverters based on a torque command of the motor, wherein the control device controls the first and second inverters such that all three-phase currents of the three-phase coils of the motor circulate in three phases from one of the first and second inverters via the power line and the other of the first and second inverters, and current amounts of a positive electrode line and a negative electrode line of the power line have different values.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] Conventionally, a driving device of this type has been proposed that includes a motor (electric motor), an inverter, and a hydraulic mechanism (see, for example, Patent Document 1). The motor includes two rotors. The hydraulic mechanism supplies hydraulic oil to a phase change mechanism provided on the rotor of the motor. In this device, when the temperature of the hydraulic oil is below a predetermined temperature, the stator coil of the motor is energized to heat the hydraulic oil. This improves the responsiveness of the phase change at low temperatures. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-44805 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 that are connected to a power line to which the power storage device is 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.In such a drive device in which the first and second inverters and the motor are H-connected, it is recognized that an important issue is to increase the amount of heat generated by the motor and the first and second inverters in order to heat the power storage device.

[0005] The main object of the drive device of the present disclosure is to increase the amount of heat generated. [Means for solving the problem]

[0006] The drive device of the present disclosure employs the following means to achieve the above-mentioned primary object: The drive device of the present disclosure includes 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 and having a plurality of first switching elements, a second inverter connected to the power line and connected to the other end of the three-phase coil and having a plurality of second switching elements, a cooling device that uses a cooling medium to cool the power storage device, the motor, and the first and second inverters, and a control device that controls the first and second inverters based on a torque command for the motor, wherein the control device controls the first and second inverters so that all phase currents of the three-phase coil of the motor circulate from one of the first and second inverters to the three phases via the power line and the other of the first and second inverters, and the amounts of current in the positive line and the negative line of the power line have different values. With this configuration, the drive device of the present disclosure can further increase the amount of heat generated by the motor and the first and second inverters. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a schematic configuration diagram of an electric vehicle equipped with a drive device according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a block diagram showing an example of a functional block in the control of the first and second inverters by the ECU at low temperatures. [Figure 3] FIG. 2 is an explanatory diagram illustrating an example of a current flow in the electric vehicle according to the embodiment. 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, switching devices 32 as load devices, a cooling device 40, and an electronic control unit (hereinafter referred to as "ECU") 50 as a control device.

[0009] 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.

[0010] The first and second inverters 22, 24 are connected to a power line 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 (first switching elements) T11 to T16 as switching elements and six diodes D11 to D16 connected in parallel to the six transistors T11 to T16, respectively. The transistors T11 to T16 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. Each of the connection points of two transistors in a pair of the transistors T11 to T16 is connected to one end of the three-phase coils 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. The transistors 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 connection points of two transistors that make up a pair of the transistors T21 to T26 are 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 the power line 28 (the positive line 28p and the 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 connected in this order on the power line 28.

[0011] The switching device 32 is attached to the positive line 28p of the power line 28. The switching device 32 includes two transistors T31 and T32 and two diodes D31 and D32. The transistors T31 and T32 are attached in series to the positive line 28p. The diode D31 is connected in parallel to the transistor T31 so that the forward direction is from the first inverter 22 to the second inverter 24. The diode D32 is connected in parallel to the transistor T32 so that the forward direction is from the second inverter 24 to the first inverter 22. The switching device 33 is attached to the negative line 28n of the power line 28. The switching device 33 includes the transistor T32 and a diode D33. The transistors T31 and T33 are attached in series to the negative line 28n. The diode D33 is connected in parallel to the transistor T33 so that the forward direction is from the first inverter 22 to the second inverter 24.

[0012] The cooling device 40 has a circulation flow path 42, a radiator 44, and an electric pump 46. The circulation flow path 42 is configured as a flow path for circulating a cooling medium such as coolant through the battery 26, the first inverter 22, the motor 20, the second inverter 24, and the radiator 44 in this order. The electric pump 46 circulates the cooling medium through the circulation flow path 42. Note that the circulation flow path 42 may also be configured as a flow path for circulating the cooling medium through the second inverter 24, the motor 20, the first inverter 22, the battery 26, and the radiator 44 in this order.

[0013] 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. The input signals include, for example, rotational position θm from rotational position sensor 20a that detects the rotational position of the rotor of motor 20, phase currents Iu, Iv, Iw of each phase of motor 20 from current sensors 22u, 22v, 22w that detect the phase current of each phase of motor 20, voltage Vb of battery 26 from voltage sensor 26v, current Ib of battery 26 from current sensor 26i, temperature Tb of battery 26 from temperature sensor 26t, voltage VH of capacitor 30 (power line 28) from voltage sensor 30v, an on / off signal from power switch 60, the operating position (shift position SP) of shift lever 61 from shift position sensor 62, the depression amount of accelerator pedal 63 (accelerator opening Acc) from accelerator pedal position sensor 64, the depression amount of brake pedal 65 (brake pedal position BP) from brake pedal position sensor 66, and vehicle speed V from 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 and 24, and to the transistors T31 and T32 of the switching device 32. 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 power storage rate SOC of the battery 26 based on the integrated value of the current Ib of the battery 26.

[0014] 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 with the set required torque Td*, and performs switching control of the transistors T11 to T16 and T21 to T26 of the first and second inverters 22 and 24 based on the set torque command Tm*.

[0015] Next, the operation of the electric vehicle 10, particularly the control of the first and second inverters 22, 24 at low temperatures, will be described. FIG. 2 is a block diagram showing an example of functional blocks used by the ECU 50 to control the first and second inverters 22, 24 at low temperatures. This functional block is applied to control the phase current of the U phase, but similar functional blocks can also be applied to the V phase and the W phase. Here, "at low temperatures" can be exemplified by a case where the outside air temperature is below a predetermined temperature (e.g., 1°C, 3°C, 5°C, etc.) or a case where the battery 26 is too low to perform its function. It is assumed that the transistors T31, T32, and T33 of the switching devices 32 and 33 are on and the electric vehicle 10 is stopped. The ECU 50 includes, as functional blocks shown in FIG. 2, a current command setting unit 500, a feedback (FB) correction term setting unit 510, and a PWM signal generating unit 520.

[0016] The current command setting unit 500 sets a current command Iu* for the motor 20 based on one-third of the required heat quantity Qreq required to heat the battery 26, and outputs the set current command Iu*. The ECU 50 determines in advance, through experiments, analysis, machine learning, or the like, the relationship between the required heat quantity Qreq and the difference between the current temperature Tb of the battery 26 measured by the temperature sensor 26t and the lower limit temperature of the temperature range in which the battery 26 can demonstrate its performance, and stores the relationship in ROM. The required heat quantity Qreq is set based on this relationship and the difference between the temperature Tb of the battery 26 measured by the temperature sensor 26t and the lower limit temperature of the temperature range in which the battery 26 can demonstrate its performance. The current command setting unit 500 sets the current command Iu* so that it is larger when the required heat quantity Qreq is large than when it is small, within a range not exceeding one-third of the maximum current quantity Immax allowed for the motor 20 and one-third of the maximum current quantity Iinvmax allowed for the first and second inverters 22, 24.

[0017] The FB correction term setting unit 510 receives the difference between the 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 of the duty command D* to cancel out the difference between the current command Iu* and the phase current Iu, and outputs the set feedback correction term Dfbu. Here, the duty command D* is the ratio of the on time of each transistor in one cycle (the sum of the on time and off time of each transistor).

[0018] The PWM signal generating unit 520 receives a duty command Du1* for the first inverter 22, which is obtained by adding a feedback correction term Dfbu to a predetermined duty command base value Db, and a duty command Du2* for the second inverter 24, which is obtained by adding the feedback correction term Dfbu to the base value Db multiplied by −1. The PWM signal generating unit 520 compares the duty commands Du1* and Du2* with a triangular wave (carrier wave) to generate a U-phase PWM signal for switching the transistors T11, T14, T21, and T24 of the first and second inverters 22 and 24. The PWM signal generating unit 520 outputs the generated PWM signal to the first and second inverters 22 and 24 to control the switching of the transistors T11, T14, T21, and T24 of the first and second inverters 22 and 24. The duty command base value Db is preset to a value different from 50%. The reason why the base value Db is set to a value different from 50% will be described later. Using the same method as described above, V-phase and W-phase PWM signals for switching the transistors T12, T13, T15, T16, T22, T23, T25, and T26 of the first and second inverters 22, 24 are generated, and the generated PWM signals are output to the first and second inverters 22, 24 to control the switching of the transistors T12, T13, T15, T16, T22, T23, T25, and T26 of the first and second inverters 22, 24. Through this control, the first and second inverters 22, 24 are feedback-controlled so that the phase currents Iu, Iv, and Iw of the motor 20 are current amounts based on the requested heat quantity Qreq.

[0019] FIG. 3 is an explanatory diagram illustrating an example of current flow in the electric vehicle 10 according to the embodiment. In FIG. 3, bold arrows indicate the direction of current. In this embodiment, the first and second inverters 22 and 24 are controlled so that the phase currents Iu, Iv, and Iw of the motor 20 flow in a direction from the first inverter 22 to the second inverter 24 and have the same current value. As a result of this control, as shown in FIG. 3, the current flows from each phase of the motor 20 through the second inverter 24, splitting into a positive line 28p (switching device 32) and a negative line 28n (switching device 33) of the power line 28, and then circulating to each phase via the first inverter 22. This promotes the temperature rise of the cooling medium in the cooling device 40 by the amount of heat generated by the motor 20, the first and second inverters 22 and 24, and the switching devices 32 and 33, thereby promoting the heating of the battery 26. This further suppresses deterioration of the battery 26 due to low temperatures.

[0020] Here, the reason why the base value Db is set to a value other than 50% will be explained. When the base value Db is set to a value other than 50%, the amount of current flowing through the positive line 28p and the amount of current flowing through the negative line 28n will differ. For example, when the base value Db exceeds 50% and the phase currents Iu, Iv, and Iw are the same, the amount of current I0n flowing through the negative line 28n will be smaller than the amount of current I0p flowing through the positive line 28p. If the maximum allowable current of the transistor T33 of the switching device 33 is smaller than the maximum allowable current of the transistors T31 and T32 of the switching device 32, setting the amount of current I0p of the positive line 28p and the amount of current I0n of the negative line 28n to be the same may result in a current exceeding the maximum allowable current of the transistor T33 of the switching device 33, making it impossible to protect the transistor T33. In such a case, by setting the basic value Db to a value exceeding 50%, the amount of current I0n in the negative line 28n is made smaller than the amount of current I0p in the positive line 28p, thereby protecting the transistor T33. Furthermore, if the maximum allowable current in the transistor T33 of the switching device 33 is greater than the maximum allowable current in the transistors T31 and T32 of the switching device 32, setting the amount of current I0p in the positive line 28p and the amount of current I0n in the negative line 28n to the same may result in a current exceeding the maximum allowable current in the transistors T31 and T32 of the switching device 32, failing to protect the transistors T31 and T32. In such a case, by setting the basic value Db to a value less than 50%, the amount of current I0p in the positive line 28p is made smaller than the amount of current I0n in the negative line 28n, thereby protecting the transistors T31 and T32. In this way, by setting the base value Db to a value other than 50%, it is possible to protect the transistors T31, T32, and T33.

[0021] In the electric vehicle 10 equipped with the drive device of the embodiment described above, all three phase currents Iu, Iv, Iw of the three-phase coil of the motor 20 circulate to the three phases from the first inverter 22 via the power line 28 and the second inverter 24, and the first and second inverters 22, 24 are controlled so that the current amounts of the positive line 28p and the negative line 28n of the power line 28 have different values, thereby making it possible to increase the amount of heat generation.

[0022] In the above-described embodiment, the first and second inverters 22, 24 are controlled so that all of the phase currents Iu, Iv, and Iw of the three phases of the three-phase coils of the motor 20 circulate from the first inverter 22 to the three phases via the power line 28 and the second inverter 24. However, the first and second inverters 22, 24 may be controlled so that the phase currents Iu, Iv, and Iw circulate from the second inverter 24 to the three phases via the power line 28 and the first inverter 22.

[0023] In the above-described embodiment, the power line 28 is provided with the switching devices 32 and 33. However, the power line 28 may be provided with only one of the switching devices 32 and 33, or may not be provided with these switching devices 32 and 33.

[0024] In the above-described embodiment, the drive unit is mounted on an electric vehicle 10 equipped with a motor 20, but the drive unit may also be mounted on a hybrid vehicle equipped with an engine in addition to a motor, a fuel cell vehicle equipped with a fuel cell in addition to a motor, or a moving body other than a vehicle or stationary construction equipment.

[0025] 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]

[0026] The present disclosure is applicable to industries such as the drive device manufacturing industry. [Explanation of symbols]

[0027] 22 first inverter, 24 second inverter, 50 electronic control unit (ECU).

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 cooling device that cools the power storage device, the motor, and the first and second inverters using a cooling medium; a control device that controls the first and second inverters based on a torque command of the motor; A drive device comprising: The control device controls the first and second inverters so that all phase currents of the three phases of the three-phase coil of the motor circulate from one of the first and second inverters to the three phases via the power line and the other of the first and second inverters, and so that the current amounts of the positive and negative lines of the power lines have different values. Drive unit.

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