Method of determining engine output power in a hybrid electric vehicle

• US 7,653,474 B2
• Filed: 05/14/2004
• Issued: 01/26/2010
• Est. Priority Date: 05/14/2004
• Status: Expired due to Fees

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations Incorporated (Motors Liquidation Co. GUC Trust)
• Inventors: Cawthorne, William R., Hubbard, Gregory A.
• Primary Examiner(s): Nguyen; Cuong H
• Application Number:
  US10/846,141
• Publication Number:
  US 20050256631A1
• Time in Patent Office: 2,083 Days
• Field of Search: 701/99, 701/22, 180/65.1, 180/65.2, 180/65.3, 180 6527- 6528, 180/2.85, 318/139, 477/3, 477/7, 602/98, 340/441, 903/903, 903/905, 903/906, 903/908
• US Class Current: 701/99
• CPC Class Codes: B60K 1/02 comprising more than one electric motor
• CPC Class Codes: B60K 6/365 with the gears having orbital motion
• CPC Class Codes: B60K 6/40 characterised by the assembly or relative disposition of components
• CPC Class Codes: B60K 6/445 Differential gearing distribution type
• CPC Class Codes: B60K 6/547 the transmission being a stepped gearing
• CPC Class Codes: B60L 15/20 for control of the vehicle or its driving motor to achieve a desired performance, e.g. speed, torque, programmed variation of speed
• CPC Class Codes: B60L 2240/441 Speed
• CPC Class Codes: B60L 2240/486 Operating parameters
• CPC Class Codes: B60L 2240/642 Slope of road
• 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 20/00 Control systems specially adapted for hybrid vehicles hybrid vehicle design, B60K6/00; electric vehicles B60L
• CPC Class Codes: B60W 20/10 Controlling the power contribution of each of the prime movers to meet required power demand
• CPC Class Codes: B60W 20/11 using model predictive control [MPC] strategies, i.e. control methods based on models predicting performance utilising navigation and traffic information in the control strategy B60W20/12
• CPC Class Codes: B60W 20/15 Control strategies specially adapted for achieving a particular effect
• CPC Class Codes: B60W 2510/0638 Engine speed
• CPC Class Codes: B60W 2510/104 Output speed
• CPC Class Codes: B60W 2510/1045 Output speed change rate
• CPC Class Codes: B60W 2510/105 Output torque
• CPC Class Codes: B60W 2520/10 Longitudinal speed
• CPC Class Codes: B60W 2552/15 : Road slope, i.e. the inclination of a road segment in the longitudinal direction
• CPC Class Codes: B60W 2710/0666 : Engine torque
• CPC Class Codes: F02D 2200/501 : Vehicle speed
• CPC Class Codes: F02D 2250/18 : Control of the engine output torque
• CPC Class Codes: F02D 41/021 : Introducing corrections for particular conditions exterior to the engine conjoint control of vehicle sub-units for propelling the vehicle B60W30/18
• CPC Class Codes: F02D 41/1497 : With detection of the mechanical response of the engine
• CPC Class Codes: F16H 2037/0866 : Power split variators with distributing differentials, with the output of the CVT connected or connectable to the output shaft
• CPC Class Codes: F16H 2037/102 : the input or output shaft of the transmission is connected or connectable to two or more differentials
• CPC Class Codes: F16H 2037/104 : Power split variators with one end of the CVT connected or connectable to two or more differentials
• CPC Class Codes: F16H 2037/106 : with switching means to provide two variator modes or ranges
• 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 90/16 : Information or communication technologies improving the operation of electric vehicles
• CPC Class Codes: Y10S 903/903 : having energy storing means, e.g. battery, capacitor

Abstract

This novel silent operating mode for a hybrid electric vehicle (HEV) reduces noise and emissions compared to traditional HEV operating modes. It is a complementary series of software control functions that allows the vehicle to operate with reduced noise and emissions where specifically needed, while phasing-in engine power where allowed. The method utilizes an energy storage system budget associated with a modal quantity of energy allocated for the mode, and is adapted to automatically adjust the operation of the vehicle to accommodate deviations from the budgeted energy amount. The method which implements the mode also adjusts the vehicle operation in conjunction with changes in the parametric conditions of the ESS, including the selective use of the engine output power. In particular, the silent operating mode comprises a method of selecting an engine output power from a speed-based engine output power and a grade-based engine output power. The grade-based engine output power may be determined from a plurality of vehicle state parameters.

Claims

1. A method of determining within a hybrid electric powertrain control strategy an engine output power for a vehicle, comprising:

determining a grade-based engine output power for the vehicle having grade entry and grade exit conditions;

determining a speed-based engine output power for the vehicle, wherein the speed-based engine output power is determined as a function of a speed of the vehicle and a battery budget factor;

selecting the engine output power for propulsion of the vehicle as the greater of the grade-based engine output power and the speed-based engine output power; and

controlling the hybrid electric powertrain in accordance with the selected engine output power.

2. The method of claim 1, wherein determining the grade-based engine output power for the vehicle, further comprises:

defining the grade entry condition having a status which is either satisfied or not satisfied as a function of a grade entry parameter associated with a dynamic state of the vehicle, wherein when the grade entry condition is satisfied it is indicative that the vehicle is on a grade;

defining the grade exit condition having a status which is either satisfied or not satisfied as a function of a grade exit parameter associated with the dynamic state of the vehicle, wherein when the grade exit condition is satisfied it is indicative that the vehicle is not on a grade;

determining the values of the grade entry parameter and the grade exit parameter;

determining the status of the grade entry condition and the grade exit condition;

comparing the grade entry condition status and grade exit condition status to determine a grade status output, wherein the grade status output is indicative of whether the vehicle is on a grade or not on a grade; and

selecting a grade-based engine output power as a function of the grade status output.

3. The method of claim 2, wherein the step of comparing is performed using a logic latch having a latch input and an unlatch input, wherein the latch input is associated with the grade entry condition and the unlatch input is associated with the grade exit condition.

4. The method of claim 1, wherein the grade-based engine output power is determined as a function of a vehicle state parameter.

5. The method of claim 4, wherein the vehicle state parameter is selected from a group consisting of a transmission output torque, a derivative of a transmission output torque, a transmission output speed, a transmission output acceleration and an engine output power.

6. The method of claim 3, wherein the logic latch is an unlatch priority latch.

7. The method of claim 2, further comprising:

filtering the grade-based engine output power to determine a filtered grade-based engine output power, wherein selecting the output power of the engine is performed by selecting from the filtered grade-based engine output power and the speed-based engine output power.

8. The method of claim 7, wherein the filter comprises an upper rate limit that is applied when the grade-based engine output power is increasing and a lower rate limit that is applied when the grade-based engine output power is decreasing.

9. The method of claim 2, wherein the grade entry condition is satisfied if the grade-entry parameter is satisfied and remains satisfied for a predetermined grade entry interval.

10. The method of claim 9, wherein the grade entry parameter is a plurality of grade entry parameters, comprising:

an output torque/output acceleration entry parameter that is a function of an output torque and an output acceleration, wherein if the output acceleration less than an output torque/output acceleration entry limit as a function of the output torque, the output torque/output acceleration entry parameter is satisfied;

an output torque entry parameter, wherein if the output torque is greater than an output torque entry limit, the output torque entry parameter is satisfied; and

an output torque derivative entry parameter, wherein if the absolute value of the output torque derivative is less than an output torque derivative entry limit, the output torque derivative parameter is satisfied.

11. The method of claim 2, wherein the grade exit parameter is a plurality of grade exit parameters, comprising:

an output torque exit parameter that is a function of the output torque, wherein if the output torque less than an output torque exit limit, the output torque exit parameter is satisfied; and

an output power exit parameter, wherein if a current value of the speed-based engine output power is greater than a current value of the grade-based engine output power, the output power exit parameter is satisfied.

12. The method of claim 11, further comprising:

an output speed exit parameter, wherein if the output speed is less than an output speed exit limit, the output speed exit parameter is satisfied.

13. A method of determining an engine output power for a vehicle powertrain system comprising an internal combustion engine, an electric machine that is operatively coupled to an energy storage system that is adapted to receive electric power from and provide electric power to the electric machine, and a transmission that is operatively coupled to the electric machine and the engine and adapted to transmit power received from one or both of them, and that is adapted for operation in a silent mode in which it is preferred that the primary power to transmission be received from the electric machine and in which the engine output power is limited to a value that is substantially less than a maximum output power of the engine, the method implemented as a computer control algorithm in a vehicle controller, comprising:

determining a grade-based engine output power for the vehicle having grade entry and grade exit conditions;

determining a speed-based engine output power for the vehicle, wherein the speed-based engine output power is determined as a function of a speed of the vehicle and a battery budget factor; and

selecting the output power for propulsion of the vehicle as the greater of the grade-based engine output power and the speed-based engine output power.

14. The method of claim 13, wherein determining the grade-based engine output power for the vehicle, further comprises:

defining the grade entry condition having a status which is either satisfied or not satisfied as a function of a grade entry parameter associated with a dynamic state of the vehicle, wherein when the grade entry condition is satisfied it is indicative that the vehicle is on a grade;

defining the grade exit condition having a status which is either satisfied or not satisfied as a function of a grade exit parameter associated with the dynamic state of the vehicle, wherein when the grade exit condition is satisfied it is indicative that the vehicle is not on a grade;

determining the values of the grade entry parameter and the grade exit parameter;

determining the status of the grade entry condition and the grade exit condition;

comparing the grade entry condition status and grade exit condition status to determine a grade status output, wherein the grade status output is indicative of whether the vehicle is on a grade or not on a grade; and

selecting a grade-based engine output power as a function of the grade status output.

15. The method of claim 14, wherein the step of comparing is performed using a logic latch having a latch input and an unlatch input, wherein the latch input is associated with the grade entry condition and the unlatch input is associated with the grade exit condition.

16. The method of claim 15, wherein the logic latch is an unlatch priority latch.

17. The method of claim 14 wherein the grade exit parameter is a plurality of grade exit parameters, comprising:

an output torque exit parameter that is a function of the output torque, wherein if the output torque less than an output torque exit limit, the output torque exit parameter is satisfied; and

an output power exit parameter, wherein if a current value of the speed-based engine output power is greater than a current value of the grade-based engine output power, the output power exit parameter is satisfied.

18. The method of claim 13, wherein the grade-based engine output power is determined as a function of a vehicle state parameter.

19. The method of claim 18, wherein the vehicle state parameter is selected from a group consisting of a transmission output torque, a derivative of a transmission output torque, a transmission output speed, a transmission output acceleration and an engine output power.

20. The method of claim 17, further comprising:

an output speed exit parameter, wherein if the output speed is less than an output speed exit limit, the output speed exit parameter is satisfied.

21. The method of claim 14, further comprising:

applying a rate limit to the grade-based engine output power to determine a rate limited grade-based engine output power, wherein selecting the output power of the engine is performed by selecting from the rate limited grade-based engine output power and the speed-based engine output power.

22. The method of claim 21, wherein the rate limit comprises an upper rate limit that is applied when the grade-based engine output power is increasing and a lower rate limit that is applied when the grade-based engine output power is decreasing.

23. The method of claim 14, wherein the grade entry condition is satisfied if the grade-entry parameter is satisfied and remains satisfied for a predetermined grade entry interval.

24. The method of claim 23, wherein the grade entry parameter is a plurality of grade entry parameters, comprising:

an output torque/output acceleration entry parameter that is a function of an output torque and an output acceleration, wherein if the output acceleration less than an output torque/output acceleration entry limit as a function of the output torque, the output torque/output acceleration entry parameter is satisfied,

an output torque entry parameter, wherein if the output torque is greater than an output torque entry limit, the output torque entry parameter is satisfied; and

an output torque derivative entry parameter, wherein if the absolute value of the output torque derivative is less than an output torque derivative entry limit, the output torque derivative parameter is satisfied.