Method for controlling engine speed in a hybrid electric vehicle

• US 20080236921A1
• Filed: 03/29/2007
• Published: 10/02/2008
• Est. Priority Date: 03/29/2007
• Status: Active Grant

• Current Assignee: GM Global Technology Operations LLC (General Motors Company)
• Original Assignee: GM Global Technology Operations LLC (General Motors Company)
• Inventors: Huseman, Steven C.
• Granted Patent: US 7,987,934 B2
• Time in Patent Office: Days
• US Class Current: 180/165
• CPC Class Codes: B60K 6/445 Differential gearing distribution type
• CPC Class Codes: B60K 6/448 Electrical distribution type
• CPC Class Codes: B60L 15/2045 for optimising the use of energy
• 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 10/24 including control of energy storage means
• 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 2510/244 Charge state
• CPC Class Codes: B60W 2710/0677 Engine power
• 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

Abstract

A method for controlling operation of a hybrid powertrain is proposed, the hybrid powertrain comprising an internal combustion engine, an electric energy storage device, an electric machine, and an electro-mechanical transmission. The engine and the electric machine and the transmission are operative to transmit torque therebetween to generate an output. The method comprises determining optimum engine operation and an engine capability, and an operator torque request. A limit to the engine capability is determined based upon optimum engine operation, engine capability, and states of the parameters of the electrical energy storage device. Power limits are determined. The limit to the engine capability is adjusted based upon the power limits of the energy storage device. The engine operation is controlled based upon the engine capability and the adjusted limit to the engine capability.

Claims

1. Method for controlling operation of a hybrid powertrain, the hybrid powertrain comprising an internal combustion engine, an energy storage system, an electric machine, and an electro-mechanical transmission, the energy storage system and electric machine electrically-operatively coupled for power flow therebetween;

and, the engine, electric machine, and the electro-mechanical transmission mechanically-operatively coupled to transmit power therebetween to generate a power flow to an output, the method comprising;

determining optimum engine operation and an engine capability, and an operator torque request;

monitoring states of parameters of the electrical energy storage device;

determining a limit to the engine capability based upon the optimum engine operation, the engine capability, and the states of the parameters of the electrical energy storage device;

determining power limits of the energy storage device based upon the states of the parameters of the energy storage device;

adjusting the limit to the engine capability based upon the power limits of the energy storage device; and

,

controlling engine operation based upon the engine capability and the adjusted limit to the engine capability.

2. The method of claim 1, further comprising controlling power transmitted from the energy storage device to the electric machine to meet the operator torque request based upon the engine operation.

3. The method of claim 2, wherein controlling power transmitted from the energy storage device to the electric machine to meet the operator torque request based upon the engine operation further comprises:

determining a power output from the engine, the engine operation controlled based upon the engine capability and the adjusted limit to the engine capability; and

,

transmitting energy from the energy storage device to the electric machine to the electro-mechanical transmission and transmitting the power output from the engine to the electro-mechanical transmission to generate the power flow to the output to meet the operator torque request.

4. The method of claim 2, wherein adjusting the limit to the engine capability based upon the power limits of the energy storage device comprises:

increasing the limit to the engine capability when the power transmitted from the energy storage device approaches the power limits of the energy storage device.

5. The method of claim 4, wherein increasing the limit to the engine capability when the power transmitted from the energy storage device approaches the power limits of the energy storage device comprises:

increasing an engine speed ramp rate sufficient to avoid surpassing power limits of the energy storage device.

6. The method of claim 1, wherein determining optimum engine operation and an engine capability comprises:

determining an optimum engine speed and engine torque, and, determining an engine speed ramp rate based upon an operating capability of the engine.

7. The method of claim 1, wherein determining the limit to the engine capability comprises determining an engine speed ramp rate limit.

8. The method of claim 1, wherein monitoring states of the parameters of the energy storage device comprises monitoring a state-of-charge, a temperature, and an electrical energy throughput.

9. The method of claim 8, wherein determining the limit to the engine capability based upon the states of the parameters of the energy storage device comprises controlling the engine speed ramp rate based upon a predetermined calibration retrievable based upon factors related to one of the state-of-charge, the battery temperature, and, the electrical energy throughput.

10. Method for controlling operation of an internal combustion engine, comprising:

mechanically-operatively coupling the engine to an electro-mechanical transmission mechanically-operatively coupled to an electric machine to transmit power therebetween to generate a power flow to an output,

electrically-operatively coupling the electric machine to an energy storage system and the electro-mechanical transmission to transmit power flow therebetween;

determining optimum engine operation and an engine speed ramp rate, and an operator torque request;

monitoring usage of the electrical energy storage device;

determining an engine speed ramp rate limit based upon the optimum engine operation, the engine speed ramp rate, and the usage of the electrical energy storage device;

determining power limits of the energy storage device based upon the usage of the energy storage device;

adjusting the engine speed ramp rate limit based upon the power limits of the energy storage device; and

,

controlling engine operation based upon the engine speed ramp rate and the adjusted engine speed ramp rate limit.

11. The method of claim 10, further comprising:

controlling transfer of energy from the electric energy storage device to the electric machine to generate the power flow to the output to meet the operator torque request.

12. The method of claim 10, wherein determining the engine speed ramp rate limit based upon the usage of the energy storage device comprises:

monitoring a state-of-charge, a temperature, and an electrical energy throughput of the energy storage device to determine the battery usage; and

,

adjusting the engine speed ramp rate limit based upon the battery usage.

13. The method of claim 12, wherein adjusting the engine speed ramp rate limit based upon battery usage comprises increasing the engine speed ramp rate with increasing battery usage.

14. The method of claim 13, wherein the battery usage is characterized by the states of the parameters of the SOC, temperature and throughput.

15. The method of claim 12, further comprising adjusting the engine speed ramp rate limit based upon a difference between an optimum engine speed and a limit engine speed determined based upon the engine speed ramp rate.

16. Method for controlling elements of a hybrid powertrain during a transient maneuver, the elements comprising an internal combustion engine, an electric energy storage device, an electric machine, and an electro-mechanical transmission, the method comprising:

mechanically-operatively coupling the engine to the electro-mechanical transmission mechanically-operatively coupled to the electric machine to transmit power therebetween to generate a power flow to an output,

electrically-operatively coupling the electric machine to the energy storage system and the electro-mechanical transmission to transmit power flow therebetween;

monitoring an operator torque request;

determining an optimum engine operation and an engine capability;

monitoring usage of the electrical energy storage device;

determining a limit to the engine capability based upon the optimum engine operation, the engine capability, and the usage of the electrical energy storage device;

determining power limits of the energy storage device based upon the usage of the energy storage device;

adjusting the limit to the engine capability when the power limits of the energy storage device approach predetermined limits;

controlling engine operation based upon the engine capability and the adjusted limit to the engine capability, and, controlling output from the electric machine to meet the operator torque request based upon the engine operation.

17. The method of claim 16, further comprising controlling power transmitted from the energy storage device to the electric machine to meet the operator torque request based upon the engine operation.

18. The method of claim 17, wherein controlling power transmitted from the energy storage device to the electric machine to meet the operator torque request based upon the engine operation further comprises:

determining a power output from the engine, the engine operation controlled based upon the engine capability and the adjusted limit to the engine capability; and

,

transmitting energy from the energy storage device to the electric machine to the electro-mechanical transmission and transmitting the power output from the engine to the electro-mechanical transmission to generate the power flow to the output to meet the operator torque request.