Engine Speed Control and Battery Power Scheduling Strategy for an Engine in a Hybrid Electric Vehicle Powertrain

• US 20100063658A1
• Filed: 09/05/2008
• Published: 03/11/2010
• Est. Priority Date: 09/05/2008
• Status: Abandoned Application

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Jarvi, Jeffrey Matthew, Greca, Scott Anthony, Wiethe, Philip Joseph, Badillo, Edward, Martin, Douglas Raymond
• Application Number:
  US12/205,289
• Publication Number:
  US 20100063658A1
• Time in Patent Office: Days
• US Class Current: 701/22
• CPC Class Codes: B60K 1/02 comprising more than one electric motor
• CPC Class Codes: B60K 6/365 with the gears having orbital motion
• 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 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 2050/0006 Digital architecture hierarchy
• CPC Class Codes: B60W 2510/244 Charge state
• CPC Class Codes: B60W 2520/28 Wheel speed
• CPC Class Codes: B60W 2540/10 Accelerator pedal position
• CPC Class Codes: B60W 2540/12 Brake pedal position
• CPC Class Codes: B60W 2710/0644 Engine speed
• CPC Class Codes: Y02T 10/40 Engine management systems
• CPC Class Codes: Y02T 10/62 Hybrid vehicles

Abstract

A control method and system is disclosed for regulating speed of an engine in a hybrid electric vehicle powertrain that includes an electric motor and gearing. An electrical power flow path and a mechanical power flow path are established. Electrical power is coordinated with mechanical power to effect an arbitrated engine speed for a given power demand that will result in an acceptable powertrain efficiency.

Claims

1. A control method for a hybrid electric vehicle powertrain having an engine and an electric motor, comprising the steps of:

determining engine speed (N1) for acceptable noise, vibration and harshness (NVH) characteristics for a given driver power demand;

determining an engine speed (N2) and torque for desirable instantaneous efficiency of the engine; and

commanding the engine to run at the lesser of engine speeds N1 and N2.

2. A control method for a hybrid electric vehicle powertrain having an engine and an electric motor, the motor complementing engine power to meet a driver demand for power at vehicle traction wheels, the method comprising the steps of:

determining driver power demand;

determining an engine speed (N2) and torque for desirable instantaneous efficiency of the engine;

determining engine speed (N1) for desirable noise, vibration and harshness (NVH) characteristics for a given driver power demand;

comparing engine speeds N1 and N2; and

commanding the engine to run at the lesser of engine speeds N1 and N2.

4. The control method set forth in claim 2, wherein the step of determining engine speed N2 comprises referring to a precalibrated relationship between engine efficiency and engine speed for a given engine torque.

6. The control method set forth in claim 2, wherein the step of determining engine speed N1 comprises referring to a precalibrated relationship between engine efficiency and engine speed for a given engine torque demand.

7. The control method set forth in claim 2, wherein determining engine speed N1 is dependent on powertrain operating variables including vehicle speed and driver wheel power demand.

9. The control method set forth in claim 2, wherein the step of determining engine speed (N3) comprises referring to a predetermined relationship between SOC, vehicle speed and driver wheel power demand.

3. A control method for a hybrid electric vehicle powertrain having an engine and an electric motor, the motor complementing engine power to meet a driver demand for power at vehicle traction wheels and a battery electrically coupled to the motor, the method comprising the steps of:

determining engine speed N2 and torque for good powertrain efficiency;

determining engine speed (N1) for good noise, vibration and harshness (NVH) characteristics;

commanding the engine to run at the lesser of engine speeds N1 and N2;

measuring battery state of charge (SOC);

determining maximum allowed engine speed N3 needed to maintain SOC when SOC is less than a predetermined value;

calculating available engine power when SOC is less than a predetermined value;

calculating engine power available to charge the battery for a given driver demand for power; and

calculating battery power for the given driver demand for power and the calculated available engine power.

5. The control method set forth in claim 3 wherein the method comprises the steps of:

determining engine speed N2 and torque for good powertrain efficiency;

determining engine speed (N1) for good noise, vibration and harshness (NVH) characteristics;

commanding the engine to run at the lesser of engine speeds N1 and N2;

measuring battery state of charge (SOC);

determining maximum allowed engine speed N3 needed to maintain SOC when SOC is less than a predetermined value;

calculating available engine power when SOC is less than a predetermined value;

calculating engine power available to charge the battery for a given driver demand for power; and

calculating battery power for the given driver demand for power and the calculated available engine power.

8. The control method set forth in claim 3, wherein determining engine speed N1 is dependent on powertrain operating variables including vehicle speed and driver wheel power demand.

10. The control method set forth in claim 3, wherein the step of calculating battery power for the given driver demand for power and the calculated available engine power includes limiting battery power to hardware limits.

11. An engine control system for a hybrid electric vehicle powertrain, comprising:

a controller configured to determine engine speed (N1) for acceptable noise, vibration and harshness (NVH) characteristics for a given driver power demand;

determine an engine speed (N2) and torque for desirable instantaneous efficiency of the engine; and

command the engine to run at the lesser of engine speeds N1 and N2.