OPTIMAL ENGINE OPERATING POWER MANAGEMENT STRATEGY FOR A HYBRID ELECTRIC VEHICLE POWERTRAIN

• US 20120059565A1
• Filed: 10/14/2011
• Published: 03/08/2012
• 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: Kozarekar, Shailesh, Kuang, Ming, Supina, Joseph, Syed, Fazal, Andreae, Morgan, Freyermuth, Vincent
• Granted Patent: US 10,023,175 B2
• Time in Patent Office: Days
• US Class Current: 701/99
• 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 for managing power in a hybrid electric vehicle powertrain having multiple components including at least two of a group comprising an engine, a motor, a generator and a high voltage battery includes computing power losses for the individual components. An engine operating speed and torque for a given vehicle speed and total power command is determined so that total power losses for powertrain components are minimized.

Claims

1. An engine power management method for a hybrid electric vehicle powertrain having an engine, an electric generator, an electric motor, a battery electrically coupled to the generator and the motor, comprising:

controlling engine speed to improve total power delivery system efficiency in response to current vehicle speed and a total power command associated with a current driver demanded power.

2. The method of claim 1 wherein the engine speed is based on power delivery losses for the engine, generator, and motor.

3. The method of claim 2 wherein the poser delivery losses are stored in a look-up table indexed by vehicle speed and wherein controlling engine speed comprises retrieving an engine speed from the look-up table based on the current vehicle speed.

4. The method of claim 1 further comprising:

determining a changed engine torque command during a transition period following a change in total power command;

computing an unfiltered engine torque command in response to a change in total power command and actual engine speed;

filtering the unfiltered engine torque command to generate a filtered engine torque command; and

modifying the engine torque command based on the filtered engine torque command during the transition period.

5. The method of claim 4 further comprising:

filtering an engine speed command following the change in total power command to control rate of increase of the engine speed until a target engine speed corresponding to the changed total power command is attained.

6. An engine power management method for a hybrid electric vehicle powertrain having separate components including at least two of a group comprising an engine, an electric motor, a generator, a battery and power transfer gearing, the components defining power flow paths to vehicle traction wheels, the method comprising:

determining an engine speed for a given vehicle speed and a given total power command to minimize total powertrain power losses wherein total powertrain losses are calculated based on component losses for each component using commanded total power, vehicle speed, and engine speed;

adding the component losses together to obtain total powertrain loss;

determining an engine speed corresponding to minimum total power loss and storing it as data in an electronic computer memory; and

accessing the data to obtain a target engine speed corresponding to current total power demand and current vehicle speed to approach a minimum total power loss and maximum total powertrain efficiency.

7. The method of claim 6 wherein accessing the data is followed by adjusting engine torque to a value corresponding to the target engine speed.

8. The method of claim 7 further comprising:

filtering an engine torque command to generate a filtered engine torque command to attain the target engine speed.

9. An engine power management method for a hybrid electric vehicle powertrain having an engine, electric motor, generator, battery and power transfer gearing, the components defining power flow paths to vehicle traction wheels, the method comprising:

controlling engine speed in response to current vehicle speed and total power demand to reduce total powertrain power losses relative to powertrain power losses associated with operating the engine at an engine speed associated with maximum engine efficiency.

10. The method of claim 9 further comprising:

calculating total powertrain power losses by adding power losses for the engine, the electric motor, the generator, the battery, and the power transfer gearing, based on vehicle speed and total power command.

11. The method of claim 10 further comprising:

storing an engine speed corresponding to minimum powertrain total power loss as a function of vehicle speed and total power command for a plurality of vehicle speeds and total power commands.

12. The method of claim 9 further comprising:

storing an engine speed corresponding to minimum powertrain total power loss for each of a plurality of vehicle speeds and total power commands; and

wherein controlling engine speed includes retrieving a target engine speed based on current vehicle speed and total power command.

13. The method of claim 12 further comprising:

adjusting engine torque to achieve the target engine speed.