Operating strategy for an electrically driven all-wheel-drive vehicle

• US 10,124,698 B2
• Filed: 08/22/2016
• Issued: 11/13/2018
• Est. Priority Date: 08/21/2015
• Status: Active Grant

• Current Assignee: Magna Steyr Fahrzeugtechnik AG & Company KG (Magna International Incorporated)
• Original Assignee: Magna Steyr Fahrzeugtechnik AG & Company KG (Magna International Incorporated)
• Inventors: Martin, Michael
• Primary Examiner(s): Sample, Jonathan L
• Application Number:
  US15/243,259
• Publication Number:
  US 20170050536A1
• Time in Patent Office: 813 Days
• Field of Search: 701 22
• CPC Class Codes: B60K 1/02 comprising more than one electric motor
• CPC Class Codes: B60K 17/356 having fluid or electric motor, for driving one or more wheels disposition of motor in, or adjacent to, traction wheel B60K7/00
• CPC Class Codes: B60K 2001/001 one motor mounted on a propulsion axle for rotating right and left wheels of this axle
• CPC Class Codes: B60L 15/2045 for optimising the use of energy
• CPC Class Codes: B60L 2240/12 Speed
• CPC Class Codes: B60L 2240/423 Torque
• CPC Class Codes: B60L 2250/26 by pedal actuation
• CPC Class Codes: B60L 2260/28 Four wheel or all wheel drive
• CPC Class Codes: B60L 2260/50 by future state prediction
• CPC Class Codes: B60W 10/08 including control of electric propulsion units, e.g. motors or generators
• CPC Class Codes: B60W 10/10 including control of change-speed gearings
• CPC Class Codes: B60W 2050/0026 Lookup tables or parameter maps
• CPC Class Codes: B60W 2540/10 Accelerator pedal position
• CPC Class Codes: B60W 2710/083 Torque
• CPC Class Codes: B60W 2710/1005 Transmission ratio engaged
• CPC Class Codes: B60W 2720/403 between front and rear axle
• CPC Class Codes: B60W 30/188 Controlling power parameters of the driveline, e.g. determining the required power
• CPC Class Codes: Y02T 10/64 Electric machine technologies in electromobility
• CPC Class Codes: Y02T 10/72 Electric energy management in electromobility

Abstract

A method for operating a vehicle, and a vehicle having at least one first electric motor, at least one second electric motor, a front axle to be driven by the at least one first electric motor, a rear axle to be driven by the at least one second electric motor. The at least one first electric motor and the at least one second electric motor are controlled to operate using a torque which is dependent upon a characteristic map that defines areas which are delimited depending on a driver-requested torque and a vehicle speed, which areas have torque distributions for the at least one first electric motor and the at least one second electric motor.

Claims

1. A method for operating a vehicle having a plurality of electric motors including at least one first electric motor and at least one second electric motor that are operated discontinuously and differently from one another, the method comprising:

driving a front axle of the vehicle by the at least one first electric motor;

driving a rear axle of the vehicle by the at least one second electric motor;

determining a torque distribution from a characteristic map that defines at least three areas which include;

a first area in which only the at least one first electric motor is activated in a manner such that the front axle is driven exclusively;

a second area in which only the at least one second electric motor is activated in a manner such that the rear axle is driven exclusively; and

a third area in which both the at least one first electric motor and the at least one second electric motor are activated in a manner such that the front axle and the rear axle are driven;

operating the at least one first electric motor and the at least one second electric motor using the determined torque distribution; and

disconnecting or decoupling a non-driven axle of the front axle and the rear axle from a drive train of the vehicle.

2. The method of claim 1, wherein the operating includes, depending on the driver-requested torque and the vehicle speed on the characteristic map, controlling the at least one first electric motor and the at least one second electric motor in accordance with the first, second or third areas so that:

only one of the at least one first electric motor and the at least one second electric motor is activated;

or

both the at least one first electric motor and the at least one second electric motor are activated.

3. The method of claim 1, wherein:

below a predefined low driver-requested torque associated with a slow vehicle speed, the determining includes determining the torque distribution to be in the first area so that the operating includes activating the at least one first electric motor but not the at least one second electric motor;

at a moderate vehicle speed, the determining includes determining the torque distribution to be in the second area so that the operating includes activating the second electric motor but not the at least one first electric motor; and

at a high vehicle speed, the determining includes determining the torque distribution to be in the third area so that the operating includes activating the first and the second electric motors.

4. The method of claim 1, wherein above a predefined high driver-requested torque associated with any vehicle speed, the determining includes determining the torque distribution to be in the third area so that the operating includes activating both the at least one first electric motor and the at least one second electric motor.

5. The method of claim 1, wherein the determining includes:

changing a currently selected area from the plurality of areas to another area of the plurality of areas based on the driver-requested torque and the vehicle speed; and

depending on the characteristic map, changing the determined torque distribution in accordance with the another area only when a plausibility check of the change to the another area has a result that would improve operation of the vehicle.

6. The method of claim 5, wherein the plausibility check represents a hysteresis of the driver-requested torque of the characteristic map.

7. The method of claim 5, wherein the plausibility check comprises conducting a temporal prediction, using one or more of:

GPS information regarding an intended route;

analyzing of a surroundings of the vehicle by recognizing traffic signs, or using ADAS sensors;

or

analyzing vehicle data such as slope sensors or steering angle sensors.

8. The method of claim 5, wherein the plausibility check comprises conducting an efficiency comparison between an efficiency which would result if the torque distribution is changed based on the change to the another area, and an efficiency which would result if the torque distribution remains unchanged.

9. The method of claim 5, wherein the plausibility check accounts for a possible derating of the at least one first electric motor and/or the at least one second electric motor.

11. The method of claim 1, wherein the characteristic map includes boundaries of the at least three areas.

12. The method of claim 11, further comprising implementing at least one transition in response to the torque distribution entering or exiting one of the boundaries by the implementing including one or more of:

switching one of the at least one first electric motor and the at least one second electric motor on or off;

coupling or decoupling the at least one first electric motor and the at least one second electric motor to/from the drive train;

setting the at least one first electric motor and the at least one second electric motor to a predefined, fixed, minimum torque;

setting the at least one first electric motor and the at least one second electric motor to a new operating torque;

or

changing a gear of a shiftable transmission of the vehicle.

10. A vehicle, comprising:

a drive train;

a plurality of electric motors including at least one first electric motor and at least one second electric motor;

a front axle to be driven by the at least one first electric motor and releasably connectable to the drive train;

a rear axle to be driven by the at least one second electric motor and releasably connectable to the drive train; and

a control unit configured to;

determine a torque distribution from a characteristic map that defines at least three areas which include;

i. a first area in which only the at least one first electric motor is activated in a manner such that the front axle is driven exclusively;

ii. a second area in which only the at least one second electric motor is activated in a manner such that the rear axle is driven exclusively; and

iii. a third area in which both the at least one first electric motor and the at least one second electric motor are activated in a manner such that the front axle and the rear axle are driven;

control the at least one first electric motor and the at least one second electric motor by operating the at least one first electric motor and the at least one second electric motor using the determined torque distribution; and

disconnect or decouple a non-driven axle of the front axle and the rear axle from a drive train of the vehicle.

13. A method for operating a vehicle, the method comprising:

determining, with a control unit, a torque distribution from a characteristic map that defines at least three areas which include;

a first area in which only a first electric motor is activated in a manner such that a front axle of the vehicle is driven exclusively;

a second area in which only a second electric motor is activated in a manner such that a rear axle of the vehicle is driven exclusively; and

a third area in which both the first electric motor and the second electric motor are activated in a manner such that the front axle and the rear axle are driven; and

operating the first electric motor and the second electric motor using the determined torque distribution.