SYSTEM AND METHOD FOR OPERATING AN ELECTRIC MOTOR BY LIMITING PERFORMANCE

• US 20090188733A1
• Filed: 03/31/2009
• Published: 07/30/2009
• Est. Priority Date: 09/19/2003
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Mack, David J.
• Granted Patent: US 8,307,928 B2
• Time in Patent Office: Days
• US Class Current: 180/65.285
• CPC Class Codes: B60K 6/445 Differential gearing distribution type
• 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 20/13 in order to stay within battery power input or output limits; in order to prevent overcharging or battery depletion
• CPC Class Codes: B60W 2510/244 Charge state
• CPC Class Codes: B60W 2530/209 Fuel quantity remaining in tank
• CPC Class Codes: B60W 2710/086 Power
• CPC Class Codes: B60W 30/146 Speed limiting
• CPC Class Codes: B60W 50/0097 Predicting future conditions
• CPC Class Codes: Y02T 10/62 Hybrid vehicles

Abstract

A method and system for limiting motor performance in a hybrid electric vehicle system. During a condition in a primary drivetrain, the method limits performance of an electric motor used in an auxiliary drivetrain to control energy consumed from a battery in the auxiliary drivetrain. A calculation or measurement is made to determine available battery energy remaining in the battery after the condition. The performance of the electric motor is then limited based on the available battery energy.

Claims

1. A method of controlling a vehicle having a primary drivetrain and an auxiliary drivetrain, the primary drivetrain relying on fuel consumption to provide energy for driving the vehicle and the auxiliary drivetrain relying on stored electrical energy to provide energy for driving the vehicle, the method comprising:

controlling the auxiliary drivetrain according to a first performance strategy when the primary drivetrain has a sufficient supply of fuel to facilitate re-charging the stored electrical energy relied upon by the auxiliary drivetrain; and

controlling the auxiliary drivetrain according to a second performance strategy when the primary drivetrain has an insufficient supply of fuel to facilitate re-charging the stored electrical energy relied upon by the auxiliary drivetrain.

2. The method of claim 1 wherein the second performance strategy consumes less of the stored electrical energy than the first performance strategy.

3. The method of claim 1 wherein the second performance strategy allows the auxiliary drivetrain to drive the vehicle for a longer period of time than the first performance strategy.

4. The method of claim 1 wherein the second performance limiting strategy includes setting a plurality of maximum vehicle speed ranges that are more restrictive than maximum vehicle speed ranges set according to the first performance strategy.

5. The method of claim 1 wherein the wherein the second performance limiting strategy includes setting a plurality of maximum power ranges that are more restrictive than maximum power ranges set according to the first performance strategy.

6. The method of claim 1 wherein the wherein the second performance limiting strategy includes setting a plurality of maximum vehicle speed and power ranges that are more restrictive than maximum vehicle speed and power ranges set according to the first performance strategy.

7. The method of claim 1 further comprising, after the primary drivetrain has the insufficient supply of fuel to facilitate re-charging the stored electrical energy relied upon by the auxiliary drivetrain, controlling the auxiliary drivetrain according to the first performance strategy if the fuel is replenished to the sufficient supply.

8. The method of claim 1 wherein the second performance limiting strategy comprises limiting actual power consumed by the electric motor to drive the vehicle.

9. The method of claim 8 wherein the actual power is limited based on a relationship between a maximum power limit and a maximum speed limit for the electric motor.

10. The method of claim 9 wherein the actual power is limited according to the following algorithm:

$\mathrm{AP}=2*\mathrm{MP}*\left(\frac{\mathrm{MS}-\mathrm{VS}}{\mathrm{MS}}\right)-\mathrm{MP}*{\left(\frac{\mathrm{MS}-\mathrm{VS}}{\mathrm{MS}}\right)}^2$

wherein;

AP=actual power (kW);

MP=maximum power (kW);

MS=maximum vehicle speed (mph); and

VS=actual vehicle speed (mph).

11. A method of controlling a vehicle having a first, liquid fuel powered drivetrain and a second, electric energy powered drivetrain, the method comprising:

determining a first amount of fuel available for powering the first powertrain;

setting operating parameters for controlling operations of the second drivetrain according to operating parameters specified by a first strategy when the first amount of fuel is above a fuel threshold; and

setting operating parameters for controlling operations of the second drivetrain according to operating parameters specified by a second strategy when the first amount of fuel is below the fuel threshold.

12. The method of claim 11 further comprising determining the fuel threshold based upon an amount of fuel consumed by the first drivetrain to charge an energy source used to power the second drivetrain above a charging threshold.

13. The method of claim 12 further comprising selecting the charging threshold based on an amount time the vehicle is to operate according to the second strategy.

14. The method of claim 12 further comprising selecting the charging threshold based on consumption habits of the second drivetrain when operated according to the second strategy.

15. The method of claim 11 further comprising setting the operating parameters such that less of a second amount of energy available for powering the second drivetrain is used when operating according to the second strategy than when operating according to the first strategy.

16. The method of claim 11 further comprising determining a second amount of energy available for powering the second drivetrain and setting the operating parameters for the second strategy based on the second amount of energy.

17. A method of controlling operating capabilities of a vehicle comprising:

sensing a first amount of fuel available within a fuel tank for providing energy suitable for use in driving the vehicle;

sensing a second amount of energy available within an electric, energy storage device for providing energy suitable for use in driving the vehicle;

automatically setting operating capabilities related to driving the vehicle according to a first strategy when the first amount of fuel is above a fuel threshold; and

automatically setting operating capabilities related to driving the vehicle according to a second strategy when the first amount of fuel is less than the fuel threshold, the second strategy consuming less of the second amount of energy than the first strategy.

18. The method of claim 17 further comprising automatically reducing the operating capabilities specified by the second strategy as a function of decreases in the second amount of energy.

19. The method of claim 17 further comprising calculating the fuel threshold based on an amount of fuel that must be consumed to charge the energy storage device above a charging threshold.

20. The method of claim 17 further comprising sensing an acceleration request made by a driver and automatically granting the acceleration request when the operating capabilities are set according to the first strategy and automatically overriding the acceleration request when the operating capabilities are set according to the second strategy.