Driving apparatus

Abstract

To facilitate a temperature increase of a battery when a temperature of the battery is low.SOLUTION: A driving apparatus includes: a battery; a motor; an inverter that is mounted on a power line from the battery and applies three-phase AC current to the motor; a current sensor that detects the three-phase AC current applied to the motor; and a control device that controls the inverter. The control device controls the inverter so that a pulsating component corresponding to an error component of the current sensor is generated in current flowing through the battery when a temperature of the battery is low.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present disclosure relates to a drive device, and more particularly to a drive device including a battery, a motor, an inverter, and a control device. [Background technology]

[0002] Conventionally, as this type of drive device, a drive device that boosts DC current from a battery using a converter and supplies it to an inverter that drives a motor has been proposed in which the converter is operated at a switching frequency lower than normal when the battery temperature is low (for example, see Patent Document 1). In this drive device, the amplitude of the ripple current passing through the battery is increased by the above control, promoting the rise in battery temperature. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2011-155788 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in a drive device that does not have a converter that boosts the DC current from the battery and supplies it to an inverter that drives the motor, since it does not have a converter, it is not possible to promote battery heating by operating the converter at a switching frequency lower than normal.

[0005] The main purpose of the drive device of the present disclosure is to promote the increase in temperature of the battery when the battery is at a low temperature. [Means for solving the problem]

[0006] The driving device of the present disclosure employs the following means to achieve the above-mentioned main object.

[0007] The drive device of the present disclosure is A drive device including a battery, a motor, an inverter attached to a power line from the battery and applying a three-phase AC current to the motor, a current sensor that detects a current of the three-phase AC applied to the motor, and a control device that controls the inverter, the control device controls the inverter so that, when the battery is at a low temperature, a pulsating component corresponding to an error component of the current sensor is generated in a current flowing through the battery. It is characterized by:

[0008] In the drive device of the present disclosure, when the battery is at a low temperature, the inverter is controlled so that a pulsating component corresponding to the error component of the current sensor is generated in the current flowing through the battery. The current sensor that detects the three-phase AC current applied to the motor has error components of offset and gain components, but the inverter can be controlled so that control does not fail even in the presence of such error components. Therefore, it is also possible to control the inverter so that a pulsating component is generated in the current flowing through the battery within the range of the allowable error component of the current sensor. By controlling the inverter in this way so that a pulsating component is generated in the current flowing through the battery, it is possible to promote the warming up of the battery. [Brief description of the drawings]

[0009] [Figure 1] 1 is a diagram showing an outline of the configuration of an electric vehicle 20 equipped with a drive device according to an embodiment of the present disclosure. [Diagram 2] 5 is a flowchart showing an example of a low-temperature pulsation process executed by an electronic control unit 50. [Diagram 3] FIG. 4 is an explanatory diagram showing an example of a change in battery current over time when inverter 34 is normally controlled and when inverter 34 is pulsating controlled. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Next, a mode (embodiment) for carrying out the present disclosure will be described. Fig. 1 is a schematic diagram showing the configuration of an electric vehicle 20 equipped with a drive device according to an embodiment of the present disclosure. As shown in the figure, the electric vehicle 20 of the embodiment includes a motor 32 for driving, an inverter 34, a battery 36, and an electronic control unit 50.

[0011] The motor 32 is configured as a three-phase AC motor and includes a rotor having a permanent magnet embedded in a rotor core and a stator having a three-phase coil wound around the stator core. The rotor of the motor 32 is connected to a drive shaft 26 that is connected to the drive wheels 22a, 22b via a differential gear 24.

[0012] The inverter 34 is used to drive the motor 32. The inverter 34 is connected to the battery 36 via a power line 38, and has 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. The transistors T11 to T16 are arranged in pairs, two at a time, so as to be on the source side and the sink side of the positive and negative lines of the power line 38, respectively. The connection points of the two transistors in each pair are connected to the coils of the corresponding phases (U phase, V phase, W phase) of the motor 32. Therefore, when a voltage is applied to the inverter 34, the electronic control unit 50 adjusts the ratio of the on time of the paired transistors T11 to T16, thereby forming a rotating magnetic field in the three-phase coils, and the motor 32 is driven to rotate.

[0013] The battery 36 is configured as a lithium ion secondary battery or a nickel-hydrogen secondary battery, and is connected to the inverter 34 via a power line 38. A smoothing capacitor 39 is attached to the power line 38.

[0014] The electronic control unit 50 is configured as a microcomputer having a CPU, a ROM, a RAM, a flash memory, and input / output ports. The electronic control unit 50 inputs the rotational position θm of the rotor of the motor 32 from the rotational position sensor 32a, the phase currents Iu and Iv of the U-phase and V-phase of the motor 32 from the current sensors 32u and 32v, the voltage Vb of the battery 36 from the voltage sensor 36a, the current Ib of the battery 36 from the current sensor 36b, the temperature Tb of the battery 36 from the temperature sensor 36c, and the voltage VL of the power line 38 (capacitor 39) from the voltage sensor 39a. The electronic control unit 50 also inputs a start signal from a start switch 60, a shift position SP which is the operation position of the shift lever 61 from a shift position sensor 62, an accelerator opening Acc which is the depression amount of the accelerator pedal 63 from an accelerator pedal sensor 64, a brake pedal position BP which is the depression amount of the brake pedal 65 from a brake pedal sensor 66, and a vehicle speed V from a vehicle speed sensor 67.

[0015] The electronic control unit 50 outputs control signals to the transistors T11 to T16 of the inverter 34. The electronic control unit 50 calculates the electrical angle θe and the number of rotations Nm of the motor 32 based on the rotation position θm, and estimates the output torque Tm of the motor 32 based on the phase currents Iu, Iv and the electrical angle θe. The output torque Tm is estimated, for example, by assuming that the sum of the currents of the phases of the motor 32 is 0, performing coordinate conversion (three-phase to two-phase conversion) of the U-phase and V-phase phase currents Iu, Iv to d-axis and q-axis currents Id, Iq using the electrical angle θe of the motor 32, and deriving the output torque Tm by applying the d-axis and q-axis currents Id, Iq to a predetermined relationship between the currents Id, Iq and the output torque Tm.

[0016] In the electric vehicle 20 of the embodiment, the electronic control unit 50 sets the traveling torque requirement Td* required for traveling (required of the drive shaft 26) as the torque command Tm* of the motor 32, and controls the transistors T11-T16 of the inverter 34 so that the motor 32 is driven by the torque command Tm*. Here, the traveling torque requirement Td* is set based on the accelerator opening Acc and the vehicle speed V. The inverter 34 is controlled, for example, by pulse width modulation (PWM) control.

[0017] In PWM control, first, assuming that the sum of the currents of the phases of the motor 32 is 0, the U-phase and V-phase currents Iu and Iv are coordinate-converted (3-phase to 2-phase conversion) to d-axis and q-axis currents Id and Iq using the electrical angle θe of the motor 32. Next, the d-axis and q-axis current commands Id* and Iq* are set based on the torque command Tm*, and the d-axis and q-axis voltage commands Vd* and Vq* are calculated so that the differences between the d-axis and q-axis current commands Id* and Iq* and the currents Id and Iq are cancelled out. Then, using the electrical angle θe of the motor 32, the d-axis and q-axis voltage commands Vd*, Vq* are coordinate-converted (2-phase to 3-phase conversion) into voltage commands Vu*, Vv*, Vw* for each phase, and PWM signals for the transistors T11 to T16 are generated by comparing these voltage commands Vu*, Vv*, Vw with the carrier voltage, thereby controlling the switching of the transistors T11 to T16.

[0018] The motor 32, the current sensors 32u and 32v, the inverter 34, the battery 36, and the electronic control unit 50 correspond to the drive device.

[0019] Next, an operation of the electric vehicle 20 of the embodiment, in particular an operation for promoting a temperature rise of the battery 36 when the temperature of the battery 36 is low, will be described. FIG.

[0020] When the low-temperature pulsation process is executed, the electronic control unit 50 first inputs the battery temperature Tb from the temperature sensor 36c (step S100), and determines whether the battery temperature Tb is less than a threshold value Tref (step S110). Here, the threshold value Tref is a threshold value for determining whether the battery 36 is in a low-temperature state, and may be, for example, 0° C. or −5° C.

[0021] When it is determined in step S110 that the battery temperature Tb is equal to or higher than the threshold value Tref, it is determined that the battery 36 is not in a low temperature state, and normal control (PWM control) of the inverter 34 is executed (step S120), and this process ends. The normal control (PWM control) of the inverter 34 has been described above.

[0022] When it is determined in step S110 that the battery temperature Tb is lower than the threshold value Tref, it is determined that the battery 36 is in a low temperature state, and inverter pulsation control is executed to control the inverter 34 so that a pulsation component is generated in the current flowing through the battery 36 within the range of the allowable error components of the current sensors 32u, 32v (step S130), and this process ends. The inverter pulsation control can be executed by superimposing a pulsation component on the U-phase and V-phase currents Iu, Iv within the range of the allowable error components in PWM control.

[0023] 3 shows an example of the change in battery current over time when the inverter 34 is normally controlled and when it is pulsatingly controlled. As shown in the figure, when the inverter 34 is normally controlled, the current flowing to the battery 36 is constant, but when the inverter 34 is pulsatingly controlled, the current flowing to the battery 36 pulsates. This makes it possible to promote the temperature rise of the battery 36.

[0024] In the drive device mounted on the electric vehicle 20 of the embodiment described above, when the battery 36 is in a low temperature state, inverter pulsation control is executed to control the inverter 34 so that a pulsating component is generated in the current flowing through the battery 36 within the range of the allowable error components of the current sensors 32u and 32v. This makes it possible to promote the warming up of the battery 36.

[0025] In the embodiment, the drive device is mounted on the electric vehicle 20, but the drive device may be mounted on a hybrid vehicle or a fuel cell vehicle. Also, the drive device may not be mounted on a vehicle.

[0026] The correspondence between the main elements of the embodiment and the main elements of the invention described in the section on means for solving the problem will be described below. In the embodiment, the battery 36 corresponds to the "battery", the motor 32 corresponds to the "motor", the inverter 34 corresponds to the "inverter", the current sensors 32u and 32v correspond to the "current sensor", and the electronic control unit 50 corresponds to the "control device".

[0027] Note that the correspondence between the main elements of the embodiment and the main elements of the invention described in the Means for Solving the Problem column does not limit the elements of the invention described in the Means for Solving the Problem column, since the embodiment is an example for specifically explaining the form for implementing the invention described in the Means for Solving the Problem column. In other words, the interpretation of the invention described in the Means for Solving the Problem column should be made based on the description in that column, and the embodiment is merely a specific example of the invention described in the Means for Solving the Problem column.

[0028] The above describes the form 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 without departing from the gist of the present disclosure. [Industrial Applicability]

[0029] The present disclosure is applicable to the electric vehicle manufacturing industry and the like. [Explanation of symbols]

[0030] 20 electric vehicle, 22a,22b drive wheels, 32 motor, 32u,32v current sensor, 34 inverter, 36 battery, 36c temperature sensor, 50 electronic control unit.

Claims

[Claim 1] A drive device including a battery, a motor, an inverter attached to a power line from the battery and applying a three-phase AC current to the motor, a current sensor that detects a current of the three-phase AC applied to the motor, and a control device that controls the inverter, the control device controls the inverter so that, when the battery is at a low temperature, a pulsating component corresponding to an error component of the current sensor is generated in a current flowing through the battery. A drive device characterized by:

Images