System and method for managing hybrid vehicle regenerative braking

• US 9,630,626 B2
• Filed: 03/06/2014
• Issued: 04/25/2017
• Est. Priority Date: 03/06/2014
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Johri, Rajit, Wang, Xiaoyong, Connolly, Francis Thomas, Colvin, Daniel Scott, Yamazaki, Mark Steven, Kuang, Ming Lang
• Primary Examiner(s): PAIGE, TYLER D
• Application Number:
  US14/199,408
• Publication Number:
  US 20150251657A1
• Time in Patent Office: 1,146 Days
• Field of Search: 701 22, 477 4
• CPC Class Codes: B60K 2006/4825 Electric machine connected or connectable to gearbox input shaft
• CPC Class Codes: B60K 6/547 the transmission being a stepped gearing
• CPC Class Codes: B60L 15/2054 by controlling transmissions or clutches
• CPC Class Codes: B60L 2240/421 Speed
• CPC Class Codes: B60L 2240/423 Torque
• CPC Class Codes: B60L 2240/507 Operating parameters
• CPC Class Codes: B60L 50/16 with provision for separate direct mechanical propulsion
• CPC Class Codes: B60L 58/13 Maintaining the SoC within a determined range
• CPC Class Codes: B60L 7/10 Dynamic electric regenerative braking B60L7/22 takes precedence
• CPC Class Codes: B60L 7/14 for vehicles propelled by ac motors
• CPC Class Codes: B60L 7/18 Controlling the braking effect B60L7/12, B60L7/14, B60L7/16 take precedence
• CPC Class Codes: B60W 20/14 in conjunction with braking regeneration
• CPC Class Codes: B60W 20/30 Control strategies involving selection of transmission gear ratio control of change speed gearings, together with other vehicle sub-units B60W10/10; HEV transmission gearing B60K6/36; gearings and control thereof F16H
• CPC Class Codes: B60W 2510/1045 Output speed change rate
• CPC Class Codes: B60W 2710/085 Torque change rate
• CPC Class Codes: B60W 30/18127 Regenerative braking
• CPC Class Codes: Y02T 10/62 Hybrid vehicles
• CPC Class Codes: Y02T 10/64 Electric machine technologies in electromobility
• 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 vehicle includes a powertrain having an electric machine configured to selectively apply regenerative braking torque to decelerate the vehicle. The vehicle also includes a controller programmed to control a rate of change of a regenerative braking torque limit during a transmission downshift that occurs during a regenerative braking event based on a change in speed of an output shaft of the powertrain caused by the transmission downshift.

Claims

1. A powertrain system for a vehicle comprising:

a powertrain having an electric machine configured to selectively apply regenerative braking torque to decelerate the vehicle; and

a controller programmed to control a rate of change of a regenerative braking torque limit during a transmission downshift that occurs during a regenerative braking event based on a change in speed of an output shaft of the powertrain caused by the transmission downshift.

2. The system of claim 1 wherein a rate of decrease of the limit during the transmission downshift is generally equal to a rate of decrease of the limit during the event before the transmission downshift.

3. The system of claim 1 wherein in the controller is further programmed to, before the transmission downshift, issue a signal indicative of a regenerative braking torque limit based on a speed of a shaft of the electric machine.

4. The system of claim 1 wherein the controller is further programmed to apply a virtual speed of the electric machine to control a rate of decrease of the limit during a torque phase of the transmission downshift.

5. The system of claim 4 wherein the virtual speed of the electric machine is based on the speed of the output shaft of the powertrain and a forecasted transmission ratio after the transmission downshift.

6. The system of claim 1 wherein a rate of decrease of the limit is reduced to avoid a compounding of the regenerative braking torque with changes in transmission torque ratio during the transmission downshift.

7. A powertrain system for a vehicle comprising:

a battery;

a powertrain having a transmission and an electric machine configured to selectively apply regenerative braking torque to both decelerate the vehicle and recharge the battery in response to braking demand; and

a controller programmed to (i) control a rate of change of a regenerative braking torque limit based on a minimum of either a motor torque capability or a recharging demand of the battery, and (ii) adjust the limit during a transmission downshift event based on a change in speed of an output shaft of the powertrain caused by the transmission downshift event.

8. The system of claim 7 wherein the limit is adjusted based on a virtual speed of the electric machine such that the adjustment to the limit occurs during a torque phase of the transmission downshift event.

9. The system of claim 8 wherein the virtual speed is based on the speed of the output shaft and a forecasted transmission ratio after the transmission downshift event.

10. The system of claim 7 wherein the adjustment to the limit is based on a virtual speed of the electric machine such that that less than a full motor torque capability is available for vehicle deceleration during the transmission downshift event.

11. The system of claim 7 wherein the regenerative braking torque limit is adjusted such that regenerative braking torque is not compounded with a change in transmission torque ratio.

12. A method of controlling regenerative braking comprising:

causing an electric machine to apply regenerative braking torque;

limiting the regenerative braking torque based on a speed of the electric machine during a regenerative braking event; and

controlling a rate of change of the limit during the regenerative braking event and a transmission downshift based on a change in speed of a powertrain output shaft.

13. The method of claim 12 wherein controlling the rate of change of the limit further comprises reducing the rate of change of the limit during a torque phase of the transmission downshift to accommodate changes in transmission torque ratio.

14. The method of claim 12 wherein controlling the rate of change of the limit is further based on a virtual speed of the electric machine such that the rate of change of the limit is reduced prior to the transmission downshift causing a change of an actual speed of the electric machine.

15. The method of claim 14 wherein the virtual speed is based on the speed of the powertrain output shaft and a forecasted transmission ratio after the transmission downshift.