Charge Depleting Energy Management Strategy for Plug-In Hybrid Electric Vehicles

• US 20090150015A1
• Filed: 12/10/2007
• Published: 06/11/2009
• Est. Priority Date: 12/10/2007
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Kuang, Ming Lang, Okubo, Shunsuke, Tamor, Michael Alan, Brigham, David Richens
• Granted Patent: US 8,140,204 B2
• Time in Patent Office: Days
• US Class Current: 701/22
• CPC Class Codes: B60K 2006/268 Electric drive motor starts the engine, i.e. used as starter motor
• 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 30/188 Controlling power parameters of the driveline, e.g. determining the required power
• CPC Class Codes: Y02T 10/62 Hybrid vehicles
• CPC Class Codes: Y02T 90/14 Plug-in electric vehicles
• CPC Class Codes: Y10S 903/93 Conjoint control of different elements

Abstract

A method for managing power distribution from an engine and a battery in a plug-in hybrid electric vehicle whereby battery power is used to meet a driver demand for power and engine power complements battery power when either battery state-of-charge limit or battery discharge power limit would be exceeded, an external power grid being used to restore battery power following battery charge depletion.

Claims

1. An energy management method for a plug-in hybrid electric vehicle powertrain having an engine, at least one electric machine, a battery, and a power transmission mechanism for delivering engine power and battery power to vehicle traction wheels, the method comprising the steps of:

monitoring battery state-of-charge;

controlling the battery state-of-charge whereby battery power discharge is below a power discharge limit;

monitoring driver demand for power at the vehicle traction wheels;

maintaining the engine in an engine-off state to achieve an all-electric drive when battery state-of-charge is greater than a predetermined battery charge threshold and driver demand for power is less than a minimum calibrated engine power threshold level for an engine start below which engine thermal efficiency becomes low;

controlling the engine to turn the engine on when the driver demand for power is equal to or greater than the minimum calibrated engine power threshold level; and

increasing engine power when a driver demand for power is greater than the sum of minimum engine power and the battery discharge limit whereby the engine operates at an engine power level greater than the minimum engine power.

3. The method set forth in claim 1 wherein the step of controlling the battery includes increasing battery power to meet driver demand for power when the monitored battery state-of-charge is greater than a minimum predetermined level.

5. The method set forth in claim 1 wherein the step of controlling the engine comprises turning the engine on in advance of an increase in driver demand for power at the vehicle traction wheels in excess of the minimum engine power, and turning the engine off when the driver demand for power at the vehicle traction wheels decreases to a value less than the driver demand for power at the traction wheels at which the engine is turned on whereby cycling of the engine between on and off states is avoided.

6. The method set forth in claim 1 wherein the step of controlling the battery includes the step of charging the battery from an external electric power source when the vehicle is inactive to restore battery state-of-charge.

8. The method set forth in claim 3 wherein the step of controlling the battery includes the step of charging the battery from an external electric power source when the vehicle is inactive to restore battery state-of-charge.

10. The method set forth in claim 5 wherein the step of controlling the battery includes the step of charging the battery from an external electric power source when the vehicle is inactive to restore battery state-of-charge.

11. The method set forth in claim 1 wherein the step of controlling the battery includes the step of turning the engine on if powertrain hardware constraints are exceeded when the vehicle is operating in an electric-only operating mode.

2. An energy management method for a plug-in hybrid electric vehicle powertrain having an engine, at least one electric machine, a battery, and a power transmission mechanism for delivering engine power and battery power to vehicle traction wheels, the method comprising the steps of:

monitoring driver demand for power;

controlling battery state-of-charge below a battery power discharge limit;

maintaining the engine in an engine-on state when a driver demand for power is less than a minimum engine power required to meet driver demand for power and powertrain hardware constraints require the engine to be on;

controlling the battery to meet a driver demand for power when the driver demand for power is in excess of the minimum engine power below which engine thermal efficiency becomes low and the driver demand for power is less than the sum of minimum engine power and a given battery power discharge level; and

increasing engine power when a driver demand for power is greater than the sum of battery discharge power limit and minimum engine power whereby the engine operates at an engine power level greater than the minimum power level.

4. The method set forth in claim 2 wherein the step of controlling the battery includes increasing battery power to meet driver demand for power when the monitored battery state-of-charge is greater than a minimum predetermined level.

7. The method set forth in claim 2 wherein the step of controlling the battery includes the step of charging the battery from an external electric power source when the vehicle is inactive to restore battery state-of-charge.

9. The method set forth in claim 4 wherein the step of controlling the battery includes the step of charging the battery from an external electric power source when the vehicle is inactive to restore battery state-of-charge.

12. The method set forth in claim 2 wherein the step of controlling the battery includes the step of turning the engine on if powertrain hardware constraints are exceeded when the vehicle is operating in an electric-only operating mode.