Downhill vehicle speed control algorithm for electric driven vehicles

• US 8,430,792 B2
• Filed: 11/08/2006
• Issued: 04/30/2013
• Est. Priority Date: 11/08/2006
• Status: Expired due to Fees

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations LLC (General Motors Company)
• Inventors: Noll, Markus
• Primary Examiner(s): Le, David D
• Application Number:
  US11/557,710
• Publication Number:
  US 20080108477A1
• Time in Patent Office: 2,365 Days
• Field of Search: 477/21, 477/23, 477/25, 303/3, 180/168, 180/170, 180/65.1, 180/65.2, 180/65, 701/22, 701/70, 701/93
• US Class Current: 477/23
• CPC Class Codes: B60K 31/04 and means for comparing one electrical quantity, e.g. voltage, pulse, waveform, flux, or the like, with another quantity of a like kind, which comparison means is involved in the development of an electrical signal which is fed into the controlling means
• CPC Class Codes: B60L 15/2009 for braking
• CPC Class Codes: B60L 2210/20 AC to AC converters
• CPC Class Codes: B60W 10/18 including control of braking systems
• CPC Class Codes: B60W 2050/0011 Proportional Integral Differential [PID] controller
• CPC Class Codes: B60W 2552/15 Road slope, i.e. the inclination of a road segment in the longitudinal direction
• CPC Class Codes: B60W 2710/18 Braking system
• CPC Class Codes: B60W 30/146 Speed limiting
• CPC Class Codes: B60W 30/18127 Regenerative braking
• CPC Class Codes: Y02T 10/64 Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/72 Electric energy management in electromobility

Abstract

A control system that prevents an electric vehicle from increasing its speed on a downhill gradient by providing regenerative braking through a traction motor. The system includes an enable circuit that provides an enable signal if certain criteria are met, such as a brake pedal and an acceleration pedal being inactive. The system further includes a controller that is enabled by the enable signal, and receives a vehicle speed signal of the speed of the vehicle. The system also includes a switch that receives the enable signal and the vehicle speed signal. When the enable circuit provides the enable signal, the switch provides a speed set-point to the controller for the last vehicle speed. If the vehicle speed signal goes above the speed set-point, the controller outputs a regenerative braking torque command to the traction motor to reduce the speed of the vehicle to the speed set-point.

Claims

1. A system for preventing the speed of an electrical vehicle from increasing, said system comprising:

an electric traction motor that is able to provide regenerative braking to the vehicle; and

a controller for controlling the electric traction motor to prevent the speed of the vehicle from increasing, said controller being responsive to a vehicle speed signal and an enable signal, said controller comparing the speed signal to a speed set-point and providing a torque command that causes the traction motor to provide regenerative braking torque to the vehicle to prevent the speed of the vehicle from increasing above the speed set-point.

2. The system according to claim 1 further comprising an enable circuit that generates the enable signal to enable the controller only if predetermined criteria are met.

3. The system according to claim 2 further comprising a switch that receives the vehicle speed signal and the enable signal, said switch outputting a last vehicle speed signal as the speed set-point to the controller when the switch is receiving the enable signal.

4. The system according to claim 2 wherein the predetermined criteria include that a position of an acceleration pedal of the vehicle is zero and a position of a brake pedal of the vehicle is zero.

5. The system according to claim 4 wherein the predetermined criteria further include that a shifter position of the vehicle is at a predetermined position.

6. The system according to claim 1 further comprising a negative saturation circuit that converts the torque command from the controller to a negative signal.

7. The system according to claim 1 wherein the controller is a proportional-integral-derivative controller.

8. The system according to claim 1 wherein the vehicle is a fuel cell vehicle including a fuel cell stack and the electric traction motor.

9. A system for preventing the speed of an electrical vehicle from increasing, said system comprising:

an electric traction motor that is able to provide regenerative braking to the vehicle;

an enable circuit that generates an enable signal only if predetermined criteria are met, said predetermined criteria including that a brake pedal and an acceleration pedal of the vehicle are not being pressed;

a switch that receives a vehicle speed signal of the speed of the vehicle and the enable signal, said switch outputting a last vehicle speed signal as a speed set-point when the switch is receiving the enable signal; and

a controller responsive to the vehicle speed signal, the speed set-point and the enable signal, said controller comparing the vehicle speed signal to the speed set-point when the controller is receiving the enable signal, and providing a torque command that causes the traction motor to provide regenerative braking torque to the vehicle to prevent the speed of the vehicle from increasing above the speed set-point.

10. The system according to claim 9 wherein the predetermined criteria further include that a shifter position of the vehicle is at a predetermined position.

11. The system according to claim 9 further comprising a negative saturation circuit that converts the torque command from the controller to a negative signal.

12. The system according to claim 9 wherein the controller is a proportional-integral-derivative controller.

13. The system according to claim 9 wherein the vehicle is a fuel cell vehicle including a fuel cell stack and the electric traction motor.

14. A method for preventing the speed of an electric vehicle from increasing, said method comprising:

providing an enable signal only if predetermined criteria are met including that a brake pedal and an acceleration pedal of the vehicle are not being pressed;

defining a speed set-point as a last vehicle speed when the enable signal is provided; and

causing an electric traction motor to provide regenerative braking torque to prevent the speed of the vehicle from increasing above the speed set-point.

15. The method according to claim 14 wherein the predetermined criteria further includes that a shifter position of the vehicle is at a predetermined position.

16. The method according to claim 14 wherein causing the electric traction motor to provide regenerative braking includes using a PID controller to provide a regenerative braking torque command as a difference between the speed set-point and an actual vehicle speed.

17. The method according to claim 16 wherein the torque command is converted to a negative signal by a negative saturation circuit.

18. The method according to claim 14 wherein the vehicle is a fuel cell vehicle including a fuel cell stack and the electric traction motor.