Electric vehicle with traction control

• US 5,492,192 A
• Filed: 08/22/1994
• Issued: 02/20/1996
• Est. Priority Date: 08/22/1994
• Status: Expired due to Fees

• Current Assignee: General Motors Corporation (Motors Liquidation Co. GUC Trust)
• Original Assignee: General Motors Corporation (Motors Liquidation Co. GUC Trust)
• Inventors: Brooks, Loran D., Kidston, Kevin S.
• Primary Examiner(s): HILL, MITCHELL
• Application Number:
  US08/293,632
• Time in Patent Office: 547 Days
• Field of Search: 180/165, 180/197, 180/65.2, 180/65.1, 180/65.3, 303/3, 303/20, 318/371, 364/426.02, 364/426.03, 364/424.01
• US Class Current: 180/165
• 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: B60L 2240/423 Torque
• CPC Class Codes: B60L 2240/463 Torque
• CPC Class Codes: B60L 3/0038 relating to sensors
• CPC Class Codes: B60L 3/10 Indicating wheel slip ; Correction of wheel slip
• CPC Class Codes: B60L 3/106 for maintaining or recovering the adhesion of the drive wheels
• CPC Class Codes: B60L 7/26 Controlling the braking effect
• CPC Class Codes: B60T 1/10 by utilising wheel movement for accumulating energy, e.g. driving air compressors
• CPC Class Codes: B60T 2270/603 ASR features related thereto
• CPC Class Codes: B60T 8/00 Arrangements for adjusting wheel-braking force to meet varying vehicular or ground-surface conditions, e.g. limiting or varying distribution of braking force by changing number of effective brake cylinders in power brake systems B60T17/10
• CPC Class Codes: B60T 8/175 Brake regulation specially adapted to prevent excessive wheel spin during vehicle acceleration, e.g. for traction control safety devices for propulsion unit control responsive to, or preventing, skidding of wheels B60K28/16
• CPC Class Codes: B60T 8/267 for hybrid systems with different kind of brakes on different axles
• CPC Class Codes: B60T 8/3205 acceleration B60T8/34, B60T8/52, B60T8/54, B60T8/56, B60T8/58, B60T8/72, B60T8/86, B60T8/88 take precedence
• CPC Class Codes: B60T 8/4863 closed systems B60T8/4845, B60T8/489 take precedence
• CPC Class Codes: Y02T 10/64 Electric machine technologies in electromobility

Abstract

A vehicle traction control system comprising an electric motor and drive system for an electric vehicle, at least one driven wheel mechanically connected to the electric motor and drive system, at least one non-driven wheel, and a controller coupled to the driven wheel, the non-driven wheel and the motor for controlling the motor and drive system to provide traction control for the vehicle by sensing a positive wheel slip between the driven and non-driven wheel, determining a control command responsive to the sensed slip, applying the control command to the motor and drive system to affect positive motor drive torque from the motor when the control command is less than an acceleration request, and applying the control command to the motor and drive system to affect regenerative braking when the control command is less than an acceleration request, wherein during regenerative braking, positive tractive force is provided by inertia of the motor and drive system, wherein the single control command controls both motor torque and braking during traction control.

Claims

1. A vehicle traction control system comprising:

an electric motor and drive system for an electric vehicle;

an accelerator pedal for providing an acceleration request;

at least one driven wheel mechanically connected to the electric motor and drive system;

at least one non-driven wheel; and

a controller coupled to the driven wheel, the non-driven wheel and the motor for controlling the motor and drive system to provide a traction control for the vehicle comprising (i) means for sensing a positive wheel slip between the driven and non-driven wheels when the electric vehicle is accelerating in response to the acceleration request to increase a road speed;

(ii) means for determining a control command responsive to the sensed slip;

(iii) means for applying the control command to the motor and drive system to affect a positive motor drive torque from the motor when the control command is less than the acceleration request;

(iv) means for applying the control command to the motor and drive system to affect regenerative braking when the control command is greater than the acceleration request, wherein regenerative braking occurs when the vehicle is accelerating to increase the road speed, wherein during regenerative braking, positive tractive force is provided by an inertia of the electric motor and drive system, wherein the control command controls both the positive motor drive torque and braking during the traction control.

2. In a vehicle with an electric motor and a drive system, an accelerator pedal, and a first wheel mechanically connected to the electric motor and drive system, wherein the motor provides motor torque, wherein the motor torque is positive during a first set of time periods, providing positive output torque and negative during a second set of time periods, providing negative output torque, wherein the positive output torque causes a vehicle acceleration and wherein the negative output torque causes a regenerative braking, a method traction control comprising the steps of:

sensing positive wheel slip between the first wheel and a second wheel when the electric vehicle is accelerating in response to an acceleration request from the accelerator pedal to increase a road speed;

determining a control command responsive to the sensed slip;

applying the control command to the motor and the drive system to affect the positive output torque from the motor when the control command is less than the acceleration request;

applying the control command to the motor and drive system to affect the regenerative braking when the control command is greater than the acceleration request, wherein the regenerative braking occurs when the vehicle is accelerating to increase the road speed, wherein during the regenerative braking, a positive tractive force is provided by an inertia of the motor and the drive system to accelerate the vehicle to increase road speed, wherein the control command controls both the positive motor drive torque and the regenerative braking during a traction control.

3. A method of traction control according to claim 2, also comprising the steps of:

sensing an operator release of the accelerator pedal;

if the release of the accelerator pedal occurs during the traction control and if the sensed slip is less than a predetermined threshold, ramping the control command to zero at a first rate;

if the release of the accelerator pedal occurs during the traction control and if the sensed slip is greater than the predetermined threshold, ramping the control command to zero at a second rate, wherein the first rate is greater than the second rate, wherein

during the ramping of the control command at the first rate, the motor torque is prevented from being the negative for greater than a first time period and wherein

during the ramping of the control command at the second rate, the motor torque is allowed to go below zero for greater than the first time period, wherein the negative output torque when the motor torque is allowed to go below zero counters inertial affects of the motor and drive train.