Operating an electric drive system with low efficiency

1. A control system configured to control a rotating electrical machine of a battery electric vehicle (BEV), comprising:

one or more microprocessors that execute a low-efficiency mode of operation for the BEV, wherein the low-efficiency mode of operation includes:

determining a high-efficiency mode current command corresponding to operation at a determined physical rotor angular velocity of a rotor of the rotating electrical machine at a commanded torque value, and increasing current supplied to the rotating electrical machine to a level corresponding to operation at an angular velocity higher than the determined physical angular velocity of the rotor at the commanded torque value to intentionally increase a temperature of the rotating electrical machine.

2. The control system recited in claim 1 , further comprising a current look-up table (LUT) for determining the current command value.

3. The control system recited in claim 1 , further comprising a torque look-up table (LUT) for determining a maximum torque value.

4. The control system recited in claim 1 , further comprising determining a rotor magnet temperature.

5. The control system recited in claim 1 , further comprising determining an inverter voltage limit and an inverter current limit.

6. The control system recited in claim 1 , further comprising determining that an ambient temperature or a rotor magnet temperature is below a predetermined temperature threshold.

7. The control system recited in claim 1 , further comprising determining that a vehicle battery temperature is below a predetermined temperature threshold.

8. The control system recited in claim 1 , further comprising determining a ratio of torque commanded relative to a maximum torque value.

9. A control system configured to control a rotating electrical machine of a battery electric vehicle (BEV), comprising:

one or more microprocessors that execute a low-efficiency mode of operation for the BEV, wherein the low-efficiency mode of operation includes:

determining that an ambient temperature or some portion of the BEV exist at or below a predetermined temperature;

determining a maximum permissible rotor angular velocity at a commanded torque value; and

adding a desired amount of inefficiency to a high-efficiency current command value that is equal to or less than a current command value at the maximum permissible rotor angular velocity at the commanded torque value.

10. The control system recited in claim 9 , further comprising a current look-up table (LUT) for determining the current command value.

11. The control system recited in claim 9 , further comprising a torque look-up table (LUT) for determining the maximum permissible change in rotor angular velocity commanded.

12. The control system recited in claim 9 , further comprising determining a rotor magnet temperature.

13. The control system recited in claim 9 , further comprising determining an inverter voltage limit and an inverter current limit.

14. The control system recited in claim 9 , further comprising determining that an ambient temperature or a rotor magnet temperature is below a predetermined temperature threshold.

15. The control system recited in claim 8 , further comprising determining a ratio of torque commanded relative to a maximum torque value.

16. A control system configured to control a rotating electrical machine of a battery electric vehicle (BEV), comprising:

one or more microprocessors that execute a low-efficiency mode of operation for the BEV, wherein the low-efficiency mode of operation includes:

determining that an ambient temperature or some portion of the BEV exist at or below a predetermined temperature; determining a high-efficiency d-axis current command for a commanded torque;

determining a maximum d-axis current command for the commanded torque;

determining a desired amount of inefficiency to be added to the high-efficiency d-axis current command that will be equal to or less than the maximum d-axis current command to generate a low-efficiency mode current command.

17. The control system recited in claim 16 , further comprising a current look-up table (LUT) for determining a maximum d-axis current.

18. The control system recited in claim 16 , further comprising a high-efficiency d-axis current look-up table (LUT) for determining the high-efficiency d-axis current command.

19. The control system recited in claim 16 , further comprising a q-axis current look-up table (LUT) for determining q-axis current corresponding to an output d-axis current command.