Electric drive axle arrangement for a road vehicle

1. An electric drive axle arrangement for a road vehicle, comprising an electric drive motor, a differential mechanism for allowing different velocities of two drive wheels driven by the drive motor, and a torque vectoring system for controlling a distribution of drive torque between the two drive wheels, the torque vectoring system comprising a torque vectoring motor, characterized in that the torque vectoring motor is a non-permanent magnet motor constructed and arranged to stop providing torque upon at least one of: a disruption at a phase conductor, a dropout of control electronics, or a short.

2. An arrangement according to claim 1 , wherein the torque vectoring motor is a Reluctance Motor.

3. An arrangement according to claim 2 , wherein the torque vectoring motor is a Switched Reluctance Motor.

4. An arrangement according to claim 2 , wherein the torque vectoring motor is a Synchronous Reluctance Motor (SyRM).

5. An arrangement according to claim 1 , wherein the torque vectoring motor is an Induction Motor.

6. An arrangement according to claim 5 , wherein the Induction Motor is a Squirrel-Cage Induction Motor (SCIM).

7. An arrangement according to claim 5 , wherein the Induction Motor is a Wound-Rotor Induction Motor (WRIM).

8. An arrangement according to claim 1 , wherein an estimated value indicative of a position of a rotor of the torque vectoring motor is obtained by surveying changes in current supplied to the torque vectoring motor.

9. An arrangement according to claim 8 , wherein the estimated value is compared to a value measured by a rotational position sensor.

10. An arrangement according to claim 9 , wherein the rotational position sensor is a resolver.

11. An arrangement according to claim 1 , wherein the drive torque from the motor is surveyed by surveying current to drive electronics for the torque vectoring motor.

12. An electric drive axle arrangement for a road vehicle, comprising an electric drive motor, first and second axle outputs driven by the electric drive motor, a differential mechanism effecting a distribution of drive torque between the first and second axle outputs, and a torque vectoring system controlling the distribution of drive torque between the first and second axle outputs, the torque vectoring system comprising a torque vectoring motor that is a non-permanent magnet motor, the torque vectoring motor connected with each of the first and second axle outputs; and wherein the torque vectoring motor is constructed and arranged to stop providing torque upon at least one of: a disruption at a phase conductor, a dropout of control electronics, or a short.

13. An arrangement according to claim 12 wherein the electric drive motor and the torque vectoring motor are disposed coaxial with one another.

14. An arrangement according to claim 12 wherein the electric drive motor has a rotor shaft with first and second ends, with a first planetary gearing disposed at the first end and a second planetary gearing disposed at the second end, the first and second planetary gearings having respective first and second sun gears, first and second planet carriers, and first and second outer rings, wherein the rotor shaft is directly connected to the first and second sun gears.

15. An arrangement according to claim 14 wherein the first planetary carrier is directly connected with the first axle output and the second planetary carrier is directly connected with the second axle output.

16. An arrangement according to claim 14 comprising a reduction gearing engaged with the torque vectoring motor, and a balancing shaft, wherein the torque vectoring motor is connected directly to the first outer ring via the reduction gearing, and the torque vectoring motor is connected directly to the second outer ring via the balancing shaft.

17. An arrangement according to claim 12 wherein the torque vectoring motor has a rotor that operates at a motor torque that is estimated by surveying current supplied to drive electronics for the torque vectoring motor.

18. A method of operating an electric drive axle arrangement for a road vehicle, that has an electric drive motor, first and second axle outputs driven by the drive motor, a differential mechanism effecting a distribution of drive torque between the first and second axle outputs, and a torque vectoring system controlling the distribution of the drive torque, the torque vectoring system comprising a torque vectoring motor that is a non-permanent magnet motor, the torque vectoring motor connected with each of the first and second axle outputs, comprising automatically providing no torque from the torque vectoring motor upon one or more of: a disruption at a phase conductor, a dropout of control electronics, or a short.

19. The method according to claim 18 comprising determining a position of the torque vectoring motor by surveying current supplied to the torque vectoring motor.

20. The method according to claim 18 comprising estimating an estimated position of the torque vectoring motor by surveying current to the torque vectoring motor, measuring a measured position of the torque vectoring motor using a position sensor, comparing the estimated position to the measured position, and deactivating the torque vectoring motor when the estimated position differs from the measured position by an amount greater than a threshold.