Optimal engine operating power management strategy for a hybrid electric vehicle powertrain

• US 7,801,662 B2
• Filed: 06/10/2008
• Issued: 09/21/2010
• Est. Priority Date: 08/02/2005
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Kuang, Ming, Andreae, Morgan, Kozarekar, Shailesh, Freyermuth, Vincent, Supina, Joseph, Syed, Fazal
• Primary Examiner(s): Black; Thomas G
• Assistant Examiner(s): Chen; Shelley
• Application Number:
  US12/136,284
• Publication Number:
  US 20080243325A1
• Time in Patent Office: 833 Days
• Field of Search: 701/22
• US Class Current: 701/101
• 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 10/08 including control of electric propulsion units, e.g. motors or generators
• CPC Class Codes: B60W 10/26 for electrical energy, e.g. batteries or capacitors
• 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 20/11 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 2710/0644 Engine speed
• CPC Class Codes: B60W 30/1882 characterised by the working point of the engine, e.g. by using engine output chart
• CPC Class Codes: Y02T 10/62 Hybrid vehicles
• CPC Class Codes: Y10S 903/903 having energy storing means, e.g. battery, capacitor
• CPC Class Codes: Y10S 903/905 Combustion engine

Abstract

A method is disclosed for managing power in a hybrid electric vehicle powertrain having multiple components, including an engine, a motor, a generator and a high voltage battery. Power losses in the individual components are computed. An engine speed corresponding to a minimum value for the power losses is selected to achieve optimal total powertrain efficiency.

Claims

1. An engine power management method for a hybrid electric vehicle powertrain having power delivery components comprising an engine, an electric generator, an electric motor, a battery electrically coupled to the generator and the motor, and gearing mechanically coupling the motor, the generator and the engine to define a power delivery system with plural power flow paths as engine mechanical power and motor and generator power are distributed to vehicle traction wheels, the method comprising the steps of:

determining power delivery loss for each of the power delivery components for a given vehicle speed and for a given total power command;

determining a total power delivery system loss by comparing the power delivery losses for each of the components for a given vehicle speed; and

determining an engine speed command corresponding to a minimum value for the total power delivery system loss whereby the powertrain operates with optimum total power delivery system efficiency.

2. The method set forth in claim 1 wherein the step of determining power loss for each of the individual power delivery components comprises execution of a calibrated functional relationship of at least two operating variables for the individual power delivery component.

3. The method sets forth in claim 1 including the step of determining a changed engine torque command during a transition period following a change in total power command;

computing an unfiltered engine torque command using the change in total power command and actual engine speed;

filtering the unfiltered engine torque command to effect a filter time lag to modify a rate of change of the engine torque command; and

increasing the engine torque command during the transition period whereby a quick response to a changed total power command is obtained.

4. The method set forth in claim 3 including the step of filtering an engine speed command following the change in total power command whereby a controlled rate of increase of the engine speed command is effected until a target engine speed is achieved corresponding to a changed total power command and a given vehicle speed.