Engine torque control for a hybrid electric vehicle using estimated engine torque

• US 6,845,305 B1
• Filed: 09/11/2002
• Issued: 01/18/2005
• Est. Priority Date: 09/11/2002
• Status: Active Grant

• Current Assignee: Ford Motor Company
• Original Assignee: Ford Motor Company
• Inventors: Ramaswamy, Deepa, Raftari, Abbas, Robichaux, Jerry D.
• Primary Examiner(s): Camby, Richard M.
• Application Number:
  US10/065,025
• Time in Patent Office: 860 Days
• Field of Search: 701/22, 701/36, 701/70, 701/84, 701/99, 701/101, 701/103, 701/104, 701/105, 180/65.2, 180/65.3, 477/2, 477/3, 477/16, 477/20
• US Class Current: 701/22
• CPC Class Codes: B60K 6/445 Differential gearing distribution type
• CPC Class Codes: B60W 10/06 including control of combustion engines
• CPC Class Codes: B60W 2050/001 Proportional integral [PI] controller
• CPC Class Codes: B60W 2710/0666 Engine torque
• CPC Class Codes: F02D 2200/1006 Engine torque losses, e.g. friction or pumping losses or losses caused by external loads of accessories
• CPC Class Codes: F02D 37/02 one of the functions being ignition
• CPC Class Codes: F02D 41/1497 With detection of the mechanical response of the engine
• CPC Class Codes: Y02T 10/62 Hybrid vehicles

Abstract

A system and method for accurate control of engine torque for a parallel/series hybrid electric vehicle (PSHEV) is disclosed. An accurate estimate of engine torque is determined from the generator motor torque of a PSHEV. The estimated engine torque can then be used to control engine torque in a closed loop torque control strategy. The invention comprises at least one controller to receive, process and output torque signals; a first control strategy to determine a modified engine torque signal from at least a desired engine torque signal; and a second control strategy to determine variables for air, fuel and spark from said modified engine torque signal. The first control strategy can include a proportional integral (PI) controller. The estimated engine torque signal can be a function of an estimated generator motor torque signal, a generator motor speed signal and an engine torque loss signal.

Claims

1. A system for controlling engine torque in a parallel/series hybrid electric vehicle, comprising:

a first control strategy embodied within a first controller to determine a modified engine torque signal from at least a desired engine torque signal and an estimated engine torque signal determined from at least an estimated generator motor torque signal; and

a second control strategy embodied within a second controller to determine variables for air, fuel and spark from said modified engine torque signal.

2. The system according to claim 1, wherein said first controller comprises a proportional integral (PI) controller.

3. The system according to claim 1, wherein said estimated engine torque signal is further a function of a generator motor speed signal and an engine torque loss signal.

4. A method for controlling engine torque in a parallel/series hybrid electric vehicle, comprising the steps of:

determining an estimated engine torque signal;

determining a modified engine torque signal from at least a desired engine torque signal and said estimated engine torque signal; and

determining variables for air, fuel and spark from said modified engine torque signal.

5. The method of claim 4, wherein said an estimated engine torque signal is determined from an estimated generator motor torque signal, from a generator motor speed signal, and from an engine torque loss signal.

6. The method of claim 4, wherein said step of determining a modified engine torque signal from at least a desired engine torque signal and an estimated engine torque signal and comprises the steps of:

determining an engine torque error signal from a difference between said desired engine torque signal and said estimated engine torque signal; and

using a proportional integral controller to operatively act upon said engine torque error signal to determine said modified engine torque signal.