HYBRID ELECTRIC VEHICLE CONTROL FOR MINIMIZING HIGH VOLTAGE BATTERY POWER LIMITS VIOLATIONS

• US 20110010031A1
• Filed: 06/29/2010
• Published: 01/13/2011
• Est. Priority Date: 07/10/2009
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Chrostowski, Thomas, Syed, Fazal Urrahman, Kuang, Ming Lang, Smith, Matthew D., Okubo, Carol Louise
• Granted Patent: US 9,545,843 B2
• Time in Patent Office: Days
• US Class Current: 701/22
• CPC Class Codes: B60K 6/445 Differential gearing distribution type
• CPC Class Codes: B60L 2240/423 Torque
• 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 2050/0031 Mathematical model of the vehicle
• CPC Class Codes: B60W 2050/0052 Filtering, filters
• CPC Class Codes: B60W 2510/0657 Engine torque
• CPC Class Codes: B60W 2510/081 Speed
• CPC Class Codes: B60W 2710/083 Torque
• CPC Class Codes: B60W 30/20 Reducing vibrations in the driveline
• CPC Class Codes: F16H 2059/743 using engine performance or power for control of gearing transmission input torque F16H2059/147
• CPC Class Codes: Y02T 10/40 Engine management systems
• CPC Class Codes: Y02T 10/62 Hybrid vehicles
• CPC Class Codes: Y02T 10/64 Electric machine technologies in electromobility

Abstract

A control system and method for controlling a hybrid electric vehicle powertrain with mechanical and electro-mechanical power sources that use an intelligent controller adapted to reduce driveline oscillations while minimizing hybrid vehicle battery limit violations. Damping of driveline torque oscillations is accomplished and violations of battery power limits are avoided by filtering estimated engine power.

Claims

1. A control system for a hybrid electric vehicle powertrain comprising:

an engine and engine controller, a battery, a motor-generator, gearing establishing power flow paths to vehicle traction wheels, and a system controller for managing power distribution to the traction wheels to meet driver demand;

the system controller being configured to monitor vehicle operating conditions, to calculate an engine output power estimate and to command a traction torque based on estimated engine output power;

the engine output power estimate being determined by input variables including generator speed, motor speed and engine torque commands to the system controller;

the system controller being configured further to filter the estimated engine output power, to reduce torque disturbances in the power flow paths, and to develop a weight determination factor for modifying the engine output power estimate;

the weight determination factor being adaptive to variable vehicle operating conditions whereby the control system emulates desired driver behavior, driver torque demand thereby being satisfied while ensuring compliance with predetermined battery charge and discharge limits.

2. The control system set forth in claim 1 wherein the system controller is configured to calculate the weight determination factor based on driver torque demand and vehicle operating conditions.

3. The control system set forth in claim 2 wherein the controller is configured to calculate a filtered engine power estimate by filtering the engine output power estimate with a narrow band notch filter and to sum the unfiltered and filtered engine output power estimates, the filtered and unfiltered engine power estimates being modified by the weight determination factor, the weight determination factor being determined by fuzzy rules corresponding to variable vehicle operating conditions.

17. The method set forth in claim 1 wherein the step of filtering the engine power estimate comprises using a narrow band notch filter that rejects engine power components that are in a natural frequency range of a power delivery element of the vehicle powertrain.

4. A method for controlling a hybrid electric vehicle powertrain having an engine, a generator, a battery, a motor and gearing, the gearing establishing power flow paths from the engine and the motor to vehicle traction wheels, and a controller configured to monitor vehicle operating conditions and to manage power distribution from the engine and the motor to vehicle traction wheels to meet driver demand, the method comprising:

computing an estimated engine output power based on at least one of a group of variables including generator speed, desired traction wheel torque and motor speed;

filtering the estimated engine output power to eliminate driveline resonant frequencies;

determining a weighting factor based in part on driver torque demand; and

applying the weighting factor to unfiltered and filtered engine output power estimates, whereby a modified engine power output estimate is obtained that will meet a driver torque demand that complies with battery power limits.

5. The method set forth in claim 4 wherein the weighting factor is a dynamically-adjusted, fuzzy-scheduled factor.

6. The method set forth in claim 5 wherein the weighting factor is based in part on vehicle operating conditions.

7. The method set forth in claim 4 wherein the engine output power estimate and unfiltered engine output power estimate are filtered with a narrow band notch filter, and wherein the step of applying the weighting factor comprises:

algebraically summing unfiltered and filtered engine power estimate with the weighting factor applied to each estimate, whereby engine output power estimates are maintained to values that will avoid driveline torque disturbances in excess of values that are in compliance with battery power limits.

8. The method set forth in claim 4 wherein the weighting factor determination is based on both driver torque demand and vehicle driving conditions.

9. The method set forth in claim 8 wherein multiple weighting factor determinations are used in developing fuzzy rules applied by a fuzzy weight scheduling.

10. The method set forth in claim 9 wherein the weighting factor determinations are dependent on whether traction wheel torque demand requires filtering.

11. The method set forth in claim 9 wherein an error between an unfiltered engine output power estimate and a filtered engine output power estimate is used in a determination of the value of the weighting factors.

12. The method set forth in claim 9 wherein a difference in battery power limits and desired electrical power on input variable is used in a determination of the weighting factors.

13. The method set forth in claim 9 wherein each fuzzy rule corresponds to a separate vehicle operating condition, whereby battery power limit violations are avoided for each vehicle operating condition.

14. The method set forth in claim 10 wherein a steady driving state is recognized for a group of driving conditions including wheel torque, changes in engine power, differences between a battery power limit, current battery power, and vehicle speed, whereby drivability is improved by reducing driveline resonance below a calibrated percentage of peak wheel torque at a given vehicle speed to reduce battery power limit violations.

15. The method set forth in claim 10 wherein a transient driving state is recognized for a group of driving conditions including wheel torque, changes in engine power, differences between a battery power limit and current battery power, and vehicle speed, whereby drivability is improved by reducing driveline resonance below a calibrated percentage of peak wheel torque at a given vehicle speed to reduce battery power limit violations.

16. The method set forth in claim 9 wherein motor speed is used in the determination of a weighting factor.

18. The method set forth in claim 7 wherein the step of filtering the estimated engine power output comprises using a narrow band notch filter that rejects engine power components that are in a natural frequency range of a power delivery element of the vehicle powertrain.