Control apparatus and control method for electric vehicle

• US 20070187158A1
• Filed: 02/15/2007
• Published: 08/16/2007
• Est. Priority Date: 02/15/2006
• Status: Active Grant

• Current Assignee: DENSO Corporation, Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: DENSO Corporation, Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Muta, Koichiro, Nagao, Ippei
• Granted Patent: US 8,046,124 B2
• Time in Patent Office: Days
• US Class Current: 180/65.100
• CPC Class Codes: B60K 28/16 responsive to, or preventing, skidding of wheels brake control systems for vehicle drive stability B60T8/1755; arrangements responsive to a speed condition for adjusting wheel braking force B60T8/32; control of vehicle driving stability otherwise than by controlling the propulsion unit only B60W30/02; preventing wheel slippage by reducing power in rail vehicles B61C15/00
• CPC Class Codes: B60K 6/445 Differential gearing distribution type
• CPC Class Codes: B60L 3/10 Indicating wheel slip ; Correction of wheel slip
• CPC Class Codes: B60L 50/16 with provision for separate direct mechanical propulsion
• CPC Class Codes: B60W 10/08 including control of electric propulsion units, e.g. motors or generators
• CPC Class Codes: B60W 20/00 Control systems specially adapted for hybrid vehicles hybrid vehicle design, B60K6/00; electric vehicles B60L
• CPC Class Codes: B60W 20/12 using control strategies taking into account route information estimation or calculation of non-directly measurable driving parameters B60W40/00
• CPC Class Codes: B60W 2520/26 Wheel slip
• CPC Class Codes: Y02T 10/62 Hybrid vehicles
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries
• CPC Class Codes: Y02T 10/7072 Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
• CPC Class Codes: Y02T 10/72 Electric energy management in electromobility

Abstract

A control apparatus for an electric vehicle includes a road surface condition detection portion, a slip determination portion, a torque reduction device, and a voltage control device. The electric vehicle includes a motor that generates drive power for the electric vehicle, and a drive device that drives the motor. The road surface condition detection portion detects the condition of a road surface on which the electric vehicle is driven. The slip determination portion determines whether the electric vehicle is slipping. The torque reduction device reduces the torque of the motor when the slip determination portion determines that the electric vehicle is slipping. The voltage control device controls a voltage input to the drive device to reduce the voltage when the road surface condition detection portion determines that the road surface has a friction coefficient lower than a predetermined value.

Claims

1. A control apparatus for an electric vehicle including a motor that generates drive power for the electric vehicle, and a drive device that drives the motor, the control apparatus comprising:

a road surface condition detection portion that detects a condition of a road surface on which the electric vehicle is driven;

a slip determination portion that determines whether the electric vehicle is slipping;

a torque reduction device that reduces torque of the motor when the slip determination portion determines that the electric vehicle is slipping; and

a voltage control device that controls a voltage input to the drive device to reduce the voltage when the road surface condition detection portion determines that the road surface has a friction coefficient lower than a predetermined value.

2. The control apparatus for the electric vehicle according to claim 1, wherein:

the electric vehicle further includes an electric storage device; and

the voltage control device includes;

a boost converter that generates the voltage input to the drive device by boosting a voltage supplied from the electric storage device according to an instruction provided to the boost converter, and

a converter control portion that outputs, to the boost converter, an instruction for reducing a rate at which the boost converter boosts the voltage, when the road surface condition detection portion determines that the road surface has a friction coefficient lower than the predetermined value.

3. The control apparatus for the electric vehicle according to claim 2, wherein the converter control portion outputs, to the boost converter, an instruction for stopping the boost converter from boosting the voltage, when the road surface condition detection portion determines that the road surface has a friction coefficient lower than the predetermined value.

4. The control apparatus for the electric vehicle according to claim 1, wherein the electric vehicle further includes a power generation device that generates electric power and supplies the generated electric power to the drive device, the control apparatus further comprising

a power generation control device that controls the power generation device to reduce an amount of electric power generated by the power generation device, when the slip determination portion determines that the electric vehicle is slipping.

5. The control apparatus for the electric vehicle according to claim 4, wherein the power generation control device controls the power generation device to increase the amount of electric power generated by the power generation device, when the road surface condition detection portion determines that the road surface has a friction coefficient lower than the predetermined value.

6. The control apparatus for the electric vehicle according to claim 1, wherein the electric vehicle further includes a power generation device that generates electric power and supplies the generated electric power to the drive device, the control apparatus further comprising

a power generation control device that controls the power generation device to increase an amount of electric power generated by the power generation device, when the road surface condition detection portion determines that the road surface has a friction coefficient lower than the predetermined value, and that further controls the power generation device to reduce the amount of electric power generated by the power generation device, when the slip determination portion later determines that the electric vehicle is slipping.

7. The control apparatus for the electric vehicle according to claim 1, wherein when the slip determination portion determines that the electric vehicle is slipping, the torque reduction device reduces the torque of the motor at a rate that is lower than a rate while no slipping is determined by the slip determination portion.

8. The control apparatus for the electric vehicle according to claim 1, wherein the electric vehicle further includes a power generation device that generates electric power and supplies the generated electric power to the drive device, and an auxiliary machine that is driven using the electric power generated by the power generation device, the control apparatus further comprising

an auxiliary machine control device that controls the auxiliary machine to increase an amount of electric power consumed by the auxiliary machine, when the slip determination portion determines that the electric vehicle is slipping.

9. The control apparatus for the electric vehicle according to claim 1, wherein the electric vehicle further includes an auxiliary machine that is connected to a drive shaft of the electric vehicle, and driven by the drive shaft, the control apparatus further comprising

an auxiliary machine control device that controls the auxiliary machine to increase an amount of load applied by the auxiliary machine, when the slip determination portion determines that the electric vehicle is slipping.

10. A control apparatus for an electric vehicle including a motor that generates drive power for the electric vehicle, and a drive device that drives the motor, wherein the electric vehicle further includes an auxiliary machine that is connected to a drive shaft of the electric vehicle, and driven by the drive shaft, the control apparatus comprising:

a road surface condition detection portion that detects a condition of a road surface on which the electric vehicle is driven;

a slip determination portion that determines whether the electric vehicle is slipping;

an auxiliary machine control device that controls the auxiliary machine to increase an amount of load applied by the auxiliary machine, when the slip determination portion determines that the electric vehicle is slipping; and

a voltage control device that controls a voltage input to the drive device to reduce the voltage, when the road surface condition detection portion determines that the road surface has a friction coefficient lower than a predetermined value.

11. A control method for an electric vehicle including a motor that generates drive power for the electric vehicle, and a drive device that drives the motor, comprising:

detecting a condition of a road surface on which the electric vehicle is driven;

determining whether the electric vehicle is slipping;

reducing torque of the motor when it is determined that the electric vehicle is slipping; and

controlling a voltage input to the drive device to reduce the voltage when it is determined that the road surface has a friction coefficient lower than a predetermined value.

12. The control method for the electric vehicle according to claim 11, wherein the step of controlling the voltage input to the drive device includes:

generating the voltage input to the drive device by boosting a voltage supplied from an electric storage device according to an instruction; and

outputting an instruction for reducing a rate at which the voltage is boosted, when it is determined that the road surface has a friction coefficient lower than the predetermined value.

13. The control method for the electric vehicle according to claim 12, wherein the step of outputting the instruction for reducing the rate at which the voltage is boosted includes outputting an instruction for stopping boosting the voltage, when it is determined that the road surface has a friction coefficient lower than the predetermined value in the step of detecting the condition of the road surface.

14. The control method for the electric vehicle according to claim 11, wherein the electric vehicle further includes a power generation device that generates electric power and supplies the generated electric power to the drive device, the control method further comprising

controlling the power generation device to reduce an amount of electric power generated by the power generation device, when it is determined that the electric vehicle is slipping in the step of determining whether the electric vehicle is slipping.

15. The control method for the electric vehicle according to claim 14, further comprising

controlling the power generation device to increase the amount of electric power generated by the power generation device, when it is determined that the road surface has a friction coefficient lower than the predetermined value in the step of detecting the condition of the road surface.

16. The control method for the electric vehicle according to claim 11, wherein the electric vehicle further includes a power generation device that generates electric power and supplies the generated electric power to the drive device, the control method further comprising:

controlling the power generation device to increase an amount of electric power generated by the power generation device, when it is determined that the road surface has a friction coefficient lower than the predetermined value in the step of detecting the condition of the road surface; and

further controlling the power generation device to reduce the amount of electric power generated by the power generation device, when it is determined later that the electric vehicle is slipping in the step of determining whether the electric vehicle is slipping.

17. The control method for the electric vehicle according to claim 11, wherein the step of reducing the torque of the motor includes when it is determined that the electric vehicle is slipping in the step of determining whether the electric vehicle is slipping, reducing the torque of the motor at a rate that is lower than a rate while no slipping is determined in the step of determining whether the electric vehicle is slipping.

18. The control method for the electric vehicle according to claim 11, wherein the electric vehicle further includes a power generation device that generates electric power and supplies the generated electric power to the drive device, and an auxiliary machine that is driven using the electric power generated by the power generation device, the control method further comprising

controlling the auxiliary machine to increase an amount of electric power consumed by the auxiliary machine, when it is determined that the electric vehicle is slipping in the step of determining whether the electric vehicle is slipping.

19. The control method for the electric vehicle according to claim 11, wherein the electric vehicle further includes an auxiliary machine that is connected to a drive shaft of the electric vehicle, and driven by the drive shaft, the control method further comprising

controlling the auxiliary machine to increase an amount of load applied by the auxiliary machine, when it is determined that the electric vehicle is slipping in the step of determining whether the electric vehicle is slipping.

20. A control method for an electric vehicle including a motor that generates drive power for the electric vehicle, and a drive device that drives the motor, wherein the electric vehicle further includes an auxiliary machine that is connected to a drive shaft of the motor, and driven by the drive shaft, the control method comprising:

detecting a condition of a road surface on which the electric vehicle is driven;

determining whether the electric vehicle is slipping;

controlling the auxiliary machine to increase an amount of load applied by the auxiliary machine, when it is determined that the electric vehicle is slipping; and

controlling a voltage input to the drive device to reduce the voltage, when it is determined that the road surface has a friction coefficient lower than a predetermined value in the step of detecting the condition of the road surface.