METHOD FOR REDUCING DRIVELINE VIBRATION IN A HYBRID ELECTRIC VEHICLE POWERTRAIN

• US 20060025906A1
• Filed: 07/29/2005
• Published: 02/02/2006
• Est. Priority Date: 07/29/2004
• Status: Active Grant

• Current Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Original Assignee: Ford Global Technologies, LLC (Ford Motor Company)
• Inventors: Kuang, Ming, Syed, Fazal, Czubay, John, Niessen, Paul
• Granted Patent: US 7,680,567 B2
• Time in Patent Office: Days
• US Class Current: 701/22
• 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 20/00 Control systems specially adapted for hybrid vehicles hybrid vehicle design, B60K6/00; electric vehicles B60L
• CPC Class Codes: B60W 2050/0025 Transfer function weighting factor
• CPC Class Codes: B60W 2050/0052 Filtering, filters
• CPC Class Codes: B60W 2710/105 Output torque
• CPC Class Codes: B60W 2720/403 between front and rear axle
• CPC Class Codes: B60W 30/20 Reducing vibrations in the driveline
• CPC Class Codes: Y02T 10/62 Hybrid vehicles

Abstract

A method is disclosed for managing torque distribution in a hybrid electric vehicle powertrain. An engine power estimation is determined for use in obtaining an optimum wheel torque command to attenuate sustained powertrain dynamic oscillations during operation of the vehicle with varying wheel torque and speed.

Claims

1. A method for attenuating dynamic oscillatory inertia torque disturbances in a powertrain for a hybrid electric vehicle, the powertrain having a first power source comprising an engine, a second power source comprising an electric motor electrically coupled to a battery and a generator, and gearing establishing mechanical power flow paths between the engine, the electric motor and the generator, the method comprising the steps of:

determining a desired vehicle wheel torque and an engine speed command in response to a driver demand for driving torque;

determining a generator torque command as a function of the engine speed command;

determining a motor torque command as a function of the desired vehicle wheel torque and the generator torque command;

calculating an engine power estimate as a function of desired vehicle wheel torque, motor torque command and generator torque command; and

filtering the engine power estimate using a weighted filtering factor that is dependent upon motor speed whereby oscillatory torque disturbances in the powertrain are attenuated.

2. The method set forth in claim 1, wherein the step of filtering the engine power estimate comprises developing a non-fluctuating filter variable and modifying an unfiltered component of the engine power estimate whereby an effective attenuated engine power estimate is developed.

3. The method set forth in claim 2, wherein the step of filtering the engine power estimate includes the step of applying the weighted filtering factor to a filtered component of the filtered engine power estimate component.

4. The method set forth in claim 3, wherein the step of filtering the engine power estimate includes the step of applying to the unfiltered engine power estimate component a filtering modifier that is equal to a value of unity less the value of the weighted filtering factor.

5. The method set forth in claim 1, wherein the step of filtering the engine power estimate comprises the step of developing a filtered component of the engine power estimate with a band stop filter having a filter time lag characteristic with respect to an unfiltered component of the engine power estimate.

11. The method set forth in claim 5, wherein the step of filtering the engine power estimate comprises execution of an algorithm defining a functional relationship between an engine power estimate before band stop filtering, an engine power estimate after band stop filtering and a weighted filter factor as follows:

Engine Power Estimate=

K_p*P<sub>eng—

pwr—

bst</sub>+(1−

K_p)* P<sub>eng—

pwr—

b4f</sub>

where;

K_p=a weighted filtering factor

P<sub>eng—

pwr—

bsf</sub>=estimated power after band stop filtering

P<sub>eng—

pwr—

b4f</sub>=estimated power before band stop Filtering.

6. A method for attenuating dynamic oscillatory inertia torque disturbances in a powertrain for a hybrid electric vehicle, the powertrain having a first power source comprising an engine, a second power source comprising an electric motor electrically coupled to a battery and a generator, and gearing establishing mechanical power flow paths between the engine, the electric motor and the generator, the method comprising the steps of:

determining a desired vehicle wheel torque and an engine speed command in response to a driver demand for driving torque;

determining generator torque command as a function of the engine speed command;

determining a motor torque command as a function of the wheel torque command and the generator torque command;

determining motor speed;

determining generator speed;

calculating an engine power estimate as a function of the desired vehicle wheel torque, the motor torque command, the generator torque command, the motor speed and the generator speed; and

filtering the engine power estimate using a weighted filtering factor that is dependent upon generator speed whereby oscillatory torque disturbances in the powertrain are attenuated.

7. The method set forth in claim 6, wherein the step of filtering the engine power estimate comprises developing a non-fluctuating filter variable and modifying an unfiltered component of the engine power estimate whereby an effective attenuated engine power estimate is developed.

8. The method set forth in claim 7, wherein the step of filtering the engine power estimate includes the step of applying the weighted filtering factor to a filtered component of the engine power estimate component.

9. The method set forth in claim 8, wherein the step of filtering the engine power estimate includes the step of applying to the unfiltered engine power estimate component a filtering modifier that is equal to a value of unity less the weighted filtering factor value.

10. The method set forth in claim 6, wherein the step of filtering the engine power estimate comprises the step of developing a filtered component of the engine power estimate with a band stop filter having a time lag characteristic with respect to an unfiltered component of the engine power estimate.

12. The method set forth in claim 6, wherein the step of calculating an engine power estimate comprises execution of an algorithm defining a functional relationship between desired vehicle wheel torque, motor torque command, generator torque command, motor speed and generator speed before filtering as follows:

$P_{\mathrm{eng\_pwr}}={\mathrm{\tau <br><br>}}_{\mathrm{wh\_des}}\times <br><br>\frac{{\mathrm{\omega <br><br>}}_{\mathrm{mot}}}{K}-\left({\mathrm{\tau <br><br>}}_{\mathrm{mot}}\times <br><br>{\mathrm{\omega <br><br>}}_{\mathrm{mot}}+{\mathrm{\tau <br><br>}}_{\mathrm{gen}}\times <br><br>{\mathrm{\omega <br><br>}}_{\mathrm{gen}}\right),$

where;

T<sub>wh—

des</sub>=desired wheel torque

T<sub>m—

cmd</sub>=motor torque command

T<sub>g—

cmd</sub>=generator torque command

ω

_mot=motor speed

ω

_gen=generator speed

K=a calibrated constant.

13. The method set forth in claim 6, wherein using a weighted filtering factor comprises executing a power estimate algorithm as follows:

Engine Power Estimate=

K_p*P<sub>eng—

pwr—

bst</sub>+(1−

K_p)*P<sub>eng—

pwr—

b4f</sub>

where;

K_p=a weighted filtering factor

P<sub>eng—

pwr—

bsf</sub>=estimated power after band stop filtering

P<sub>eng—

pwr—

b4f</sub>=estimated power before band stop Filtering.