Control device for electric vehicle

Abstract

A motor vibration damping control unit (81) performs vibration damping control of a motor (4). A generator vibration damping control unit (82) performs vibration damping control of a generator (5). A switching control unit (83) switches to the vibration damping control by the generator vibration damping control unit (82) when the motor (4) and a drive shaft (9) are disconnected by a motor clutch (6) during parallel travel, and switches to the vibration damping control by the motor vibration damping control unit (81) when the motor (4) and the drive shaft (9) are connected by the motor clutch (6) during parallel travel.

Description

Control device for an electric vehicle

[0001] The present invention relates to a control device for an electric vehicle.

[0002] Conventionally, in an electric vehicle having an engine and a motor as drive sources, there is known one provided with an engine clutch for disconnecting the engine and the drive shaft, and a motor clutch for disconnecting the motor and the drive shaft (Patent Document 1). Patent Document 1 describes that when the engine and the drive shaft are connected by the engine clutch, vibration control of the drive shaft is performed by a generator that assists the engine. Also, Patent Document 1 describes that when the motor and the drive shaft are connected by the motor clutch, vibration control of the drive shaft is performed by the motor.

[0003] Also, an electric vehicle that performs parallel running using both an engine and a motor as drive sources is known. In parallel running, it is conceivable to connect or disconnect the motor and the drive shaft according to the need for assistance by the motor while the engine is connected to the drive shaft.

[0004] In such parallel running, when both the engine and the motor are connected to the drive shaft, if vibration control is performed by both the motor and the generator, hunting occurs where the rotational speed does not stabilize, and vibration occurs in the electric vehicle.

[0005] Japanese Patent No. 7331936

[0006] The present invention has been made in view of the above circumstances, and an object thereof is to provide a control device for an electric vehicle that can reduce vibration during parallel running.

[0007] To achieve the above objective, the electric vehicle control device according to the present invention is characterized as follows: The electric vehicle control device controls an electric vehicle that is capable of parallel driving, comprising: a battery; an engine that drives a drive shaft; a motor that drives the drive shaft by receiving power from the battery; a generator that generates electricity using the power of the engine and also drives the drive shaft by receiving power from the battery; and a clutch that connects and disconnects the motor and the drive shaft, wherein the engine and the drive shaft are directly connected and the motor and the drive shaft are connected and disconnected by the clutch, and further comprises: a first vibration damping control unit that performs vibration damping control of the drive shaft using the motor; a second vibration damping control unit that performs vibration damping control of the drive shaft using the generator; and a switching control unit that switches to vibration damping control by the second vibration damping control unit when the motor and the drive shaft are disconnected by the clutch during parallel driving, and switches to vibration damping control by the first vibration damping control unit when the motor and the drive shaft are connected by the clutch during parallel driving.

[0008] The electric vehicle control device of the present invention has the effect of reducing vibrations during parallel driving.

[0009] The present invention has been briefly described above. Furthermore, the details of the present invention will be further clarified by referring to the accompanying drawings and reading through the embodiments for carrying out the invention described below (hereinafter referred to as "embodiments").

[0010] Figure 1 is a block diagram of an electric vehicle to which the electric vehicle control device of the present invention is applied. Figure 2 is a functional block diagram of the control unit shown in Figure 1. Figure 3 is a time chart of the motor clutch state, engine clutch state, torque output from the generator, torque output from the motor, output ratio of the generator torque compensation value, and output ratio of the motor torque compensation value.

[0011] Specific embodiments of the present invention will be described below with reference to the figures.

[0012] Figure 1 is a block diagram of an electric vehicle to which the electric vehicle control device of the present invention is applied. The electric vehicle 1 is a plug-in hybrid vehicle (PHEV) or hybrid vehicle (HEV) that uses an engine 3 and a motor 4 as drive sources and is capable of external charging or external power supply. The electric vehicle 1 comprises a battery 2, an engine 3, a motor 4, a generator 5, an engine clutch 6, a motor clutch 7, and a control unit 8 as the "electric vehicle control device".

[0013] Battery 2 is charged with electricity generated by the generator 5 (described later) and electricity regenerated by the motor 4 (described later).

[0014] Engine 3 constitutes the power source in the electric vehicle and generates power by burning fuel. Engine 3 drives the drive shaft 9 attached to the drive wheel 10.

[0015] Motor 4 drives the drive shaft 9 by receiving power from battery 2. Motor 4 also has a regenerative function, recovering deceleration energy as electricity by being rotated along with the drive shaft 9 during deceleration. Motor 4 constitutes the power source in the electric vehicle 1.

[0016] The generator 5 generates electricity using the power of the engine 3 and also drives the drive shaft 9 by receiving power from the battery 2. The generator 5 constitutes the power source of the electric vehicle 1.

[0017] The engine clutch 6 engages and disengages the engine 3 and generator 5 from the drive shaft 9. The engine clutch 6 is provided to be movable from a disengagement position, where it disconnects the engine 3 and generator 5 from the drive shaft 9, to a connection position, where it connects the engine 3 and generator 5 from the drive shaft 9.

[0018] When the engine clutch 6 connects the engine 3 and generator 5 to the drive shaft 9, the power generated by the engine 3 and generator 5 is transmitted to the drive shaft 9. When the engine clutch 6 disconnects the engine 3 and generator 5 from the drive shaft 9, the power generated by the engine 3 and generator 5 is not transmitted to the drive shaft 9.

[0019] The motor clutch 7 connects and disconnects the motor 4 and the drive shaft 9. The motor clutch 7 is provided so as to be movable from a disconnection position that disconnects the motor 4 and the drive shaft 9 to a connection position that connects the motor 4 and the drive shaft 9. When the motor clutch 7 connects the motor 4 and the drive shaft 9, the power generated by the motor 4 is transmitted to the drive shaft 9. When the motor clutch 7 disconnects the motor 4 and the drive shaft 9, the power generated by the motor 4 is not transmitted to the drive shaft 9.

[0020] The control unit 8 consists of a storage unit that stores programs and the like, and a computer that operates according to the program. As shown in Figure 2, the control unit 8 has a motor vibration damping control unit 81 (first vibration damping control unit), a generator vibration damping control unit 82 (second vibration damping control unit), and a switching control unit 83.

[0021] The motor vibration control unit 81 controls the torque of the motor 4 to suppress torsional vibrations applied to the drive shaft 9. The motor vibration control unit 81 includes a notch filter processing unit 811, a backlash removal processing unit 812, a rotation speed change acquisition unit 813, a MOT torque ripple FB compensation processing unit 814, and an adder 815.

[0022] The notch filter processing unit 811 performs notch filter processing to remove the natural vibration component of the torsional vibration of the transmission system from the motor 4 to the drive wheel 10. The backlash reduction processing unit 812 performs backlash reduction processing to reduce the backlash of the motor 4.

[0023] The rotational speed change acquisition unit 813 acquires the amount of change in the rotational speed of the drive shaft 9 from the rotational speed sensor 11 installed on the drive shaft 9. The MOT torque ripple FB compensation processing unit 814 calculates a motor torque compensation value (first vibration damping control amount) that reduces torsional vibrations occurring in the drive shaft 9 based on the amount of change in rotational speed. The adder 815 adds the motor torque compensation value to the torque command that has undergone notch filtering and backlash reduction processing and outputs it to the motor 4. As a result, the motor 4 can suppress torsional vibrations of the drive shaft 9.

[0024] The generator vibration control unit 82 controls the torque of the generator 5 to suppress torsional vibrations applied to the drive shaft 9, thereby controlling the vibration of the generator 5. The generator vibration control unit 82 includes a notch filter processing unit 821, a backlash removal processing unit 822, a rotational speed change acquisition unit 823, a GEN torque ripple FB compensation processing unit 824, and an adder 825.

[0025] The notch filter processing unit 821 performs notch filter processing to remove the natural vibration component of the torsional vibration of the transmission system from the generator 5 to the drive wheel 10. The backlash reduction processing unit 822 performs backlash reduction processing to reduce the backlash of the generator 5.

[0026] The rotational speed change acquisition unit 823 acquires the amount of change in the rotational speed of the drive shaft 9 from the rotational speed sensor 11 installed on the drive shaft 9. The GEN torque ripple FB compensation processing unit 824 calculates a generator torque compensation value (second vibration damping control amount) to reduce torsional vibrations occurring in the drive shaft 9 based on the amount of change in rotational speed. The adder 825 adds the generator torque compensation value to the torque command that has undergone notch filtering and backlash reduction processing and outputs it to the generator 5. As a result, the generator 5 can suppress vibrations of the drive shaft 9.

[0027] When the motor 4 and drive shaft 9 are disconnected by the motor clutch 7 during parallel driving with the engine 3 and drive shaft 9 directly connected, the switching control unit 83 switches to vibration damping control by the generator vibration damping control unit 82. When the motor 4 and drive shaft 9 are connected by the motor clutch 7 during parallel driving with the engine 3 and drive shaft 9 directly connected, the switching control unit 83 switches to vibration damping control by the motor vibration damping control unit 81.

[0028] The detailed operation of the switching control unit 83, as outlined above, will be described below with reference to the time chart in Figure 3. As shown in Figure 3(B), the engine 3 and generator 5 and the drive shaft 9 are always connected by the engine clutch 6 during parallel driving. In Figure 3(A), "moving" indicates that the motor clutch 7 is moving from the disengaged position to the connected position, or from the connected position to the disengaged position, and is between the disengaged and connected positions.

[0029] First, let's explain the case where the motor clutch 7 is in the disengaged position. As shown in Figure 3(C), the torque transmitted from the motor 4 to the drive shaft 9 becomes 0, and the motor 4 stops. The generator 5 generates torque according to the torque command and transmits it to the drive shaft 9. Also, as shown in Figure 3(D), the switching control unit 83 stops the operation of the MOT torque ripple FB compensation processing unit 814 and stops the vibration damping control by the motor vibration damping control unit 81. The switching control unit 83 also outputs the generator torque compensation value as 100% to the adder 825, causing the generator vibration damping control unit 82 to perform vibration damping control.

[0030] The movement of the motor clutch 7 from the disengaged position to the engaged position (moving) will be described below. As shown in Figure 3(C), the torque transmitted from the motor 4 to the drive shaft 9 remains at 0, and the motor 4 is stopped. The generator 5 continues to generate torque according to the torque command and transmits it to the drive shaft 9. As shown in Figure 3(D), the switching control unit 83 continues to stop the operation of the MOT torque ripple FB compensation processing unit 814, and continues to stop the vibration control by the motor vibration control unit 81. The switching control unit 83 continues the vibration control by the generator vibration control unit 82.

[0031] Next, we will explain the case when the motor clutch 7 has finished moving to the engagement position. When the motor clutch 7 has finished moving to the engagement position, torque is transmitted from the motor 4 to the drive shaft 9. At this time, as shown in Figure 3(C), the motor 4 continuously and gradually increases the torque from 0 to the torque corresponding to the torque command value. The generator 5 continuously and gradually decreases the torque and then stops. As a result, when the motor clutch 7 is in the engagement position, the motor 4 outputs torque according to the torque command value, and the generator 5 stops.

[0032] As shown in Figure 3(D), once the motor clutch 7 has finished moving to the engagement position, the switching control unit 83 gradually reduces the generator torque compensation value calculated by the GEN torque ripple FB compensation processing unit 824 from 100% to 80%, 70%, and so on. In this embodiment, the switching control unit 83 reduces the generator torque compensation value by a first reduction rate, and then reduces it to 0% by a second reduction rate, which is higher than the first reduction rate.

[0033] The switching control unit 83 reduces the generator torque compensation value to 0%, stops the vibration damping control by the generator vibration damping control unit 82, and after a certain period T1 has elapsed, it gradually increases the motor torque compensation value calculated by the MOT torque ripple FB compensation processing unit 814 from 0% to 10%, 20%, and so on. In this embodiment, the switching control unit 83 increases the motor torque compensation value at a first increase rate, and then increases it to 100% at a second increase rate lower than the first increase rate. When the motor torque compensation value reaches 100%, the motor 4 reaches the torque corresponding to the torque command value, the torque of the generator 5 becomes 0, and the generator 5 stops.

[0034] Next, we will explain the movement of the motor clutch 7 from the engaged position to the disengaged position (movement). As shown in Figure 3(C), when the motor clutch 7 starts moving to the disengaged position, the torque transmitted from the motor 4 to the drive shaft 9 becomes 0. At the same time, the generator 5 starts outputting torque according to the torque command. At this time, as shown in Figure 3(D), when the motor clutch 7 starts moving to the disengaged position, the switching control unit 83 switches the motor torque compensation value from 100% to 0%, stopping the vibration damping control by the motor vibration damping control unit 81. The switching control unit 83 also switches the generator torque compensation value from 0% to 100%, starting the vibration damping control by the generator vibration damping control unit 82.

[0035] The following describes the case when the motor clutch 7 has finished moving to the disengagement position. As shown in Figure 3(C), the motor 4 remains stopped, and the generator 5 continues to output torque according to the torque command. The switching control unit 83 continues to stop the vibration damping control by the motor vibration damping control unit 81, and continues the vibration damping control by the generator vibration damping control unit 82.

[0036] According to the embodiment described above, when the motor 4 and drive shaft 9 are disconnected by the motor clutch 7 during parallel driving, the switching control unit 83 switches to vibration damping control by the generator vibration damping control unit 82, and when the motor 4 and drive shaft 9 are connected by the motor clutch 7 during parallel driving, it switches to vibration damping control by the motor vibration damping control unit 81. This reduces the need for both the motor vibration damping control unit 81 and the generator vibration damping control unit 82 to perform vibration damping control simultaneously, thereby reducing vibrations during parallel driving.

[0037] Incidentally, after the motor clutch 7 is fully engaged, torsional vibration is likely to occur due to backlash. For this reason, if the vibration damping control by the generator vibration damping control unit 82 is stopped immediately after the motor clutch 7 is fully engaged, there will be a period during which vibration damping control is not performed, and the suppression of torsional vibration will not be sufficient. According to the embodiment described above, the switching control unit 83 performs the above switching by continuously and gradually decreasing the generator torque compensation value of the generator vibration damping control unit 82 and continuously and gradually increasing the motor torque compensation value of the motor vibration damping control unit 81 after the motor clutch 7 has completed moving from the disconnection position where it disconnects the motor 4 and the drive shaft 9 to the connection position where it connects the motor 4 and the drive shaft 9 during parallel driving. This makes it possible to perform vibration damping control by the generator vibration damping control unit 82 immediately after the motor clutch 7 is fully engaged, when torsional vibration is likely to occur. Furthermore, even if the switching timing is off and vibration damping control by the motor vibration damping control unit 81 and the generator vibration damping control unit 82 is performed simultaneously, the vibration during parallel driving can be reduced because the generator torque compensation value and motor torque compensation value are small.

[0038] According to the embodiment described above, the switching control unit 83 performs the switching by stopping the vibration damping control by the generator vibration damping control unit 82 after the motor clutch 7 has moved from the disconnection position where it disconnects the motor 4 and the drive shaft 9 to the connection position where it connects the motor 4 and the drive shaft 9 during parallel driving, and then starting the vibration damping control by the motor vibration damping control unit 81 after a certain period of time T1 has elapsed. In this way, by providing a certain period of time during which neither the motor vibration damping control unit 81 nor the generator vibration damping control unit 82 performs vibration damping control, the simultaneous operation of both the motor vibration damping control unit 81 and the generator vibration damping control unit 82 is reduced, thereby reducing vibration during parallel driving.

[0039] According to the embodiment described above, the switching control unit 83 reduces the generator torque compensation value by a first reduction rate, and then reduces it by a second reduction rate which is higher than the first reduction rate. As a result, while the torque of the generator 5 is high and vibration damping control can be effectively performed with the generator torque compensation value, the generator torque compensation value can be increased by gradually reducing it, and vibration damping control can be performed with high accuracy. When the torque of the generator 5 is low and vibration damping control can no longer be effectively performed with the generator torque compensation value, the generator torque compensation value can be quickly reduced to prevent it from overlapping with the vibration damping control by the motor vibration damping control unit 81.

[0040] According to the embodiment described above, the switching control unit 83 amplifies the motor vibration damping control unit 81 at a first amplification factor, and then amplifies it at a second amplification factor that is lower than the first amplification factor. When the torque of the motor 4 is low and vibration damping control cannot be effectively performed with the motor torque compensation value, the motor torque compensation value can be rapidly increased. When the torque of the motor 4 increases, the motor torque compensation value can be increased gradually so that the motor torque compensation value does not become too high relative to the torque of the motor 4.

[0041] According to the above-described embodiment, when the switching control unit 83 starts moving the motor clutch 7 from the connection position connecting the motor 4 and the drive shaft 9 to the disconnection position during parallel running, the vibration control of the motor vibration control unit 81 is stopped, and the vibration control of the generator vibration control unit 82 is started. Thereby, the vibration control by the generator vibration control unit 82 can be started immediately when the assist by the generator 5 is started.

[0042] According to the above-described embodiment, the switching control unit 83 continuously and gradually reduces the generator torque compensation value and continuously and gradually increases the motor torque compensation value after the motor clutch 7 has completed moving from the disconnection position to the connection position during parallel running. However, this is not the only case. For example, after the motor clutch 7 has completed moving from the disconnection position to the connection position, the generator torque compensation value may be switched from 100% to 0%, and then the motor torque compensation value may be switched from 0% to 100%.

[0043] According to the above-described embodiment, the switching control unit 83 stops the vibration control by the generator vibration control unit 82 and then starts the vibration control by the motor vibration control unit 81 after a lapse of a certain time T1 after the motor clutch 7 has completed moving from the disconnection position to the connection position during parallel running. However, this is not the only case. The motor vibration control unit 81 may start the vibration control by the motor vibration control unit 81 simultaneously when the vibration control by the generator vibration control unit 82 stops, or starting from slightly before the vibration control stops.

[0044] According to the above-described embodiment, the switching control unit 83 reduces the generator torque compensation value at a first reduction rate and then reduces it at a second reduction rate higher than the first reduction rate. Also, after amplifying the motor torque compensation value at a first amplification rate, it amplifies it at a second amplification rate lower than the first amplification rate. However, this is not the only case. The generator torque compensation value may be reduced at a constant reduction rate, or the motor torque compensation value may be increased at a constant increase rate.

[0045] Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention.

[0046] The present invention aims to provide a control device for electric vehicles that can reduce vibrations during parallel driving. This invention, which achieves this effect, is particularly useful for electric vehicle control devices.

[0047] 1. Electric vehicle 2. Battery 3. Engine 4. Motor 5. Generator 7. Motor clutch (clutch) 8. Control unit (control device) 9. Drive shaft 81. Motor vibration control unit (first vibration control unit) 82. Generator vibration control unit (second vibration control unit) 83. Switching control unit

Claims

1. A control device for an electric vehicle that controls an electric vehicle capable of parallel driving, wherein the engine and the drive shaft are directly connected and the motor and the drive shaft are connected and disconnected by the clutch, comprising: a first vibration damping control unit that controls vibration damping of the drive shaft using the motor; a second vibration damping control unit that controls vibration damping of the drive shaft using the generator; and a switching control unit that switches to vibration damping control by the second vibration damping control unit when the motor and the drive shaft are disconnected by the clutch during parallel driving.

2. A control device for an electric vehicle according to claim 1, wherein the switching control unit performs the switching by continuously and gradually decreasing the second vibration damping control amount of the second vibration damping control unit and continuously and gradually increasing the first vibration damping control amount of the first vibration damping control unit after the clutch has completed moving from a disconnection position in which it disconnects the motor and the drive shaft to a connection position in which it connects the motor and the drive shaft during parallel driving.

3. A control device for an electric vehicle according to claim 1, wherein the switching control unit performs the switching after the clutch has completed moving from a disconnection position in which it disconnects the motor and the drive shaft during parallel driving to a connection position in which it connects the motor and the drive shaft, by stopping the vibration damping control by the second vibration damping control unit and then starting the vibration damping control by the first vibration damping control unit after a certain period of time has elapsed.

4. A control device for an electric vehicle according to claim 2, wherein the switching control unit reduces the second vibration damping control amount by a first reduction rate, and then reduces it by a second reduction rate that is higher than the first reduction rate.

5. A control device for an electric vehicle according to claim 2, wherein the switching control unit amplifies the first vibration damping control amount by a first amplification factor, and then amplifies it by a second amplification factor that is lower than the first amplification factor.

6. A control device for an electric vehicle according to any one of claims 1 to 5, wherein the switching control unit stops the vibration damping control of the first vibration damping control unit and starts the vibration damping control of the second vibration damping control unit when the clutch starts moving from a connection position connecting the motor and the drive shaft to a disconnection position disconnecting the motor and the drive shaft during parallel driving.

Images