Heat generation for the purpose of warming up an EV battery in cold weather

1 . A method, comprising:

receiving a torque command for a motor torque causing operation of a vehicle electric motor at a desired speed;

receiving a heat power command for an amount of heat for warming a battery powering the vehicle electric motor;

determining an operating point of the vehicle electric motor corresponding to both the motor torque and the amount of heat by at least

measuring a speed of the vehicle electric motor,

determining a traction output power as a product of the motor torque and the measured speed of the vehicle electric motor,

determining a required total motor power equal to the traction output power plus the heat power command, and

determining direct-axis (d-axis) and quadrature axis (q-axis) current commands for controlling the electric motor to operate at the determined operating point based upon the required total motor power such that the operating point is selected away from a maximum torque per amp (MTPA) operating point to increase motor losses while maintaining the motor torque; and

controlling the vehicle electric motor based on the determined operating point.

2 . The method according to claim 1 wherein determining the d-axis and q-axis current commands for controlling the vehicle electric motor further comprises:

measuring battery output power; and

subtracting the battery output power from the required total motor power to determine a required electrical input power for the electrical motor.

3 . The method according to claim 2 , further comprising:

applying a proportional-integral-derivative (PID) control to the required electrical input power.

4 . The method according to claim 3 , further comprising:

applying thermal limits to an output of the PID control.

5 . The method according to claim 1 , wherein determining an operating point further comprises:

processing the torque command to determine the motor torque.

6 . The method according to claim 1 , wherein the heat power command is based on one or more of a battery temperature and an ambient temperature.

7 . The method according to claim 1 , wherein determining the d-axis and q-axis current commands further comprises:

based on the torque command and the heat power command, looking up the d-axis and q-axis current commands in power loss tables that include operating points corresponding to both MTPA operating points and non-MTPA operating points having higher power losses.

8 . The method according to claim 7 , wherein the current commands are forwarded to an integrated dynamic-control module.

9 . The method according to claim 1 , wherein controlling the vehicle electric motor further comprises:

controlling an inverter coupled to the vehicle electric motor.

10 . A system, comprising:

a vehicle electric motor; and

a motor controller configured to

receive a torque command for a motor torque causing operation of the vehicle electric motor at a desired speed,

receive a heat power command for an amount of heat for warming a battery powering the vehicle electric motor,

determine an operating point of the vehicle electric motor corresponding to both the motor torque and the amount of heat by at least

measuring a speed of the vehicle electric motor,

determining a traction output power as a product of the motor torque and the measured speed of the vehicle electric motor,

determining a required total motor power equal to the traction output power plus the heat power command, and

determining direct-axis (d-axis) and quadrature axis (q-axis) current commands for controlling the electric motor to operate at the determined operating point based upon the required total motor power such that the operating point is selected away from a maximum torque per amp (MTPA) operating point to increase motor losses while maintaining the motor torque, and

control the vehicle electric motor based on the determined operating point.

11 . The system according to claim 10 , wherein the motor controller is configured to determine the d-axis and q-axis current commands for controlling the vehicle electric motor by:

measuring battery output power; and

subtracting the battery output power from the required total motor power to determine a required electrical input power for the electric motor.

12 . The system according to claim 11 , wherein the motor controller is configured to:

apply a proportional-integral-derivative (PID) control to the determined required electrical input power.

13 . The system according to claim 12 , wherein the motor controller is configured to:

apply thermal limits to an output of the PID control.

14 . The system according to claim 10 , wherein the motor controller is further configured to determine the operating point by:

processing the torque command to determine the torque.

15 . The system according to claim 10 , wherein the heat power command is based on one or more of a battery temperature and an ambient temperature.

16 . The system according to claim 10 , wherein the motor controller is further configured to determine the d-axis and q-axis current commands by:

based on the torque command and the heat power command, looking up d-axis and q-axis current commands in power loss tables that include operating points corresponding to both MTPA operating points and non-MTPA operating points having higher power losses.

17 . The system according to claim 16 , further comprising:

an integrated dynamic-control module to which the current commands are forwarded.

18 . The system according to claim 10 , wherein the motor controller is further configured to control the vehicle electric motor by:

controlling an inverter coupled to the vehicle electric motor.