Braking control system for electric automobile

• US 5,839,800 A
• Filed: 11/12/1996
• Issued: 11/24/1998
• Est. Priority Date: 12/06/1994
• Status: Expired due to Term

• Current Assignee: Mitsubishi Jidosha Kogyo Kabushiki Kaisha
• Original Assignee: Mitsubishi Jidosha Kogyo Kabushiki Kaisha
• Inventors: Kato, Masaaki, Kawamura, Nobuyuki, Furukawa, Nobuya, Koga, Hisamitsu, Owada, Tomiji, Kumagai, Naotake
• Primary Examiner(s): Poon, Peter M.
• Application Number:
  US08/687,489
• Time in Patent Office: 742 Days
• Field of Search: 303/152, 303/151, 303/3, 303/15, 303/20, 318/371, 318/376, 188/156, 188/158, 188/159
• US Class Current: 303/152
• CPC Class Codes: B60K 6/46 Series type
• CPC Class Codes: B60L 15/2009 for braking
• CPC Class Codes: B60L 2240/423 Torque
• CPC Class Codes: B60L 2240/545 Temperature
• CPC Class Codes: B60L 2250/26 by pedal actuation
• CPC Class Codes: B60L 7/10 Dynamic electric regenerative braking B60L7/22 takes precedence
• CPC Class Codes: B60L 7/24 with additional mechanical or electromagnetic braking
• CPC Class Codes: B60L 7/26 Controlling the braking effect
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 10/08 including control of electric propulsion units, e.g. motors or generators
• CPC Class Codes: B60W 10/18 including control of braking systems
• CPC Class Codes: B60W 10/26 for electrical energy, e.g. batteries or capacitors
• 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 20/13 in order to stay within battery power input or output limits; in order to prevent overcharging or battery depletion
• CPC Class Codes: Y02T 10/62 Hybrid vehicles
• CPC Class Codes: Y02T 10/64 Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/72 Electric energy management in electromobility
• CPC Class Codes: Y02T 10/92 Energy efficient charging or discharging systems for batteries, ultracapacitors, supercapacitors or double-layer capacitors specially adapted for vehicles
• CPC Class Codes: Y10S 903/947 Characterized by control of braking, e.g. blending of regeneration, friction braking

Abstract

A braking control system for an electric automobile combines the use of mechanical braking and regenerative braking by a motor. Namely, a braking control system for the electrical automobile, which permits the combined use of regenerative braking and mechanical braking, is provided with target braking force setting unit (9) for setting a target braking force on the basis of a brake pedal stroke, regeneration control system (4A,5A) for setting a target regenerative braking force on the basis of the brake pedal stroke and then controlling regenerative braking by the motor in accordance with the target regenerative braking force, and mechanical braking control unit (24) for controlling operation of a mechanical brake system (B) in accordance with a difference between said target braking force and an actual braking force determined based on a detected deceleration of a vehicle. These features make it possible to surely obtain a desired braking force and also to promote the recovery of energy by regenerative braking.

Claims

1. A braking control system for an electric automobile, said braking control system combining a use of regenerative braking by a motor and mechanical braking by a mechanical brake system upon application of brakes, comprising:

brake pedal stroke detection means for detecting a stroke of a brake pedal;

target braking force setting means for setting a target braking force on a basis of the brake pedal stroke detected by said brake pedal stroke detection means;

regeneration control means for setting a target regenerative braking force on a basis of the brake pedal stroke detected by said brake pedal stroke detection means, and controlling regenerative braking by said motor in accordance with said set target regenerative braking force;

deceleration detecting means for detecting a deceleration of the automobile; and

mechanical braking control means for controlling operation of said mechanical braking system, after initiation of the regenerative braking, in accordance with a difference between said target braking force and an actual braking force determined based on the detected deceleration from said deceleration detecting means.

2. The braking control system according to claim 1, further comprising:

battery condition detecting means for detecting a condition of a battery, wherein

said regeneration control means sets the target regenerative braking force in accordance with the brake pedal stroke detected by said brake pedal stroke detection means and the condition of said battery detected by said battery condition detecting means.

3. The braking control system according to claim 2, wherein said battery condition detecting means detects a temperature of said battery, and

said regeneration control means reduces said set target regenerative braking force as the temperature of said battery increases.

4. The braking control system according to claim 1, further comprising:

regenerated voltage detection means for detecting a voltage regenerated by said motor; and

generated voltage detection means for detecting a voltage generated by a generator driven by an internal combustion engine to charge a battery, wherein

said regeneration control means reduces said set target regenerative braking force when the regenerated voltage exceeds the generated voltage.

8. The method of claim 1, further comprising:

detecting a first voltage regenerated by the motor; and

detecting a second voltage generated by a generator driven by an internal combustion engine to charge a battery,

wherein said step for setting said target regenerative braking force reduces said set target regenerative braking force when said first voltage exceeds said second voltage.

5. A brake control method for an electric automobile having a regenerative braking system, which includes a motor for regenerating power, and a mechanical braking system, comprising:

detecting a depression stroke of a brake pedal;

setting a target braking force based on said detected stroke of the brake pedal;

setting a target regenerative braking force based on said detected stroke of the brake pedal;

controlling the regenerative braking based on said set target regenerative braking force;

decelerating the automobile by the regenerative braking;

detecting an actual deceleration of the automobile; and

controlling the mechanical braking system, after initiation of said regenerative braking, based on a difference between said set target braking force and an actual braking force determined based on said detected actual deceleration of the automobile.

6. The method of claim 5, further comprising:

detecting a condition of a battery, wherein said step for setting said target regenerative braking force sets said target regenerative braking force based on said detected depression stroke and said detected battery condition.

7. The method of claim of claim 6, wherein said step for detecting the condition of the battery detects a temperature of the battery, and

said step for setting said target regenerative braking force reduces said set target regenerative braking force as said detected temperature of the battery increases.