Method for torque control systems and methods based on rotor temperature

Patent metadata

Field	Value
Publication number	US-10333448-B2
Application number	US-201715482935-A
Country	US
Kind code	B2
Filing date	Apr 10, 2017
Priority date	Apr 10, 2017
Publication date	Jun 25, 2019
Grant date	Jun 25, 2019

Abstract

An electric motor control system of a vehicle includes a current command module configured to, based on a motor torque request for an electric motor of the vehicle, generate a first d-axis current command for the electric motor and a first q-axis current command for the electric motor. An adjustment module is configured to, based on a speed of a rotor of the electric motor and the motor torque request, selectively determine at least one of a d-axis current adjustment and a q-axis current adjustment based on a temperature of the rotor of the electric motor. An adjusting module is configured to produce a second d-axis current command for the electric motor by adjusting the first d-axis current command based on the d-axis current adjustment and to produce a second q-axis current command for the electric motor by adjusting the first q-axis current command based on the q-axis current adjustment.

First claim

What is claimed is:

1. An electric motor control system of a vehicle, comprising:
a current command module configured to, based on a motor torque request for an electric motor of the vehicle, generate a first d-axis current command for the electric motor and a first q-axis current command for the electric motor;
an adjustment module configured to, based on a speed of a rotor of the electric motor and the motor torque request, selectively determine at least one of a d-axis current adjustment and a q-axis current adjustment based on a temperature of the rotor of the electric motor;
an adjusting module configured to produce a second d-axis current command for the electric motor by adjusting the first d-axis current command based on the d-axis current adjustment and to produce a second q-axis current command for the electric motor by adjusting the first q-axis current command based on the q-axis current adjustment; and
a switching control module configured to, based on the second d-axis current command and the second q-axis current command, control switching of an inverter module and apply power to stator windings of the electric motor from an energy storage device,
wherein:
the adjustment module is configured to:
when the speed is greater than a predetermined speed, set both the d-axis current adjustment and the q-axis current adjustment to a predetermined value; and
when the speed is less than the predetermined speed, based on whether the motor torque request is greater than a predetermined torque, selectively determine one of the d-axis current adjustment and the q-axis current adjustment based on the temperature of the rotor of the electric motor; and

the adjusting module is configured to:
based on the d-axis current adjustment being equal to the predetermined value, set the second d-axis current command equal to the first d-axis current command; and
based on the q-axis current adjustment being equal to the predetermined value, set the second q-axis current command equal to the first q-axis current command,

wherein the adjusting module is configured to:
one of:
set the second d-axis current command equal to the first d-axis current command plus the d-axis current adjustment; and
set the second d-axis current command equal to the first d-axis current command multiplied by the d-axis current adjustment; and

one of:
set the second q-axis current command equal to the first q-axis current command plus the q-axis current adjustment; and
set the second d-axis current command equal to the first q-axis current command multiplied by the q-axis current adjustment.

2. The electric motor control system of claim 1 wherein the adjustment module is configured to:
when the speed is less than the predetermined speed and the motor torque request is greater than the predetermined torque, determine the d-axis current adjustment based on the temperature of the rotor of the electric motor; and
when the speed is less than the predetermined speed and the motor torque request is less than the predetermined torque, determine the q-axis current adjustment based on the temperature of the rotor of the electric motor.

3. The electric motor control system of claim 2 wherein the adjustment module is further configured to, when the speed is less than the predetermined speed and the motor torque request is greater than the predetermined torque, set the q-axis current adjustment to the predetermined value.

4. The electric motor control system of claim 2 wherein the adjustment module is further configured to, when the speed is less than the predetermined speed and the motor torque request is less than the predetermined torque, set the d-axis current adjustment to the predetermined value.

5. The electric motor control system of claim 2 wherein the adjustment module is further configured to, when the speed is less than the predetermined speed and the motor torque request is less than the predetermined torque, determine the d-axis current adjustment based on the first d-axis current command, a d-axis inductance of the electric motor, a q-axis inductance of the electric motor, and a predetermined gain.

6. The electric motor control system of claim 2 wherein the adjustment module is configured to, when the speed is less than the predetermined speed and the motor torque request is less than the predetermined torque:
determine a magnetic flux linkage of the electric motor based on the temperature of the rotor;
determine a variation in the magnetic flux linkage based on the temperature of the rotor; and
determine the q-axis current adjustment based on the magnetic flux linkage and the variation in the magnetic flux linkage.

7. The electric motor control system of claim 2 wherein the adjustment module is configured to, when the speed is less than the predetermined speed and the motor torque request is greater than the predetermined torque:
determine a variation in magnetic flux linkage of the electric motor based on the temperature of the rotor; and
determine the d-axis current adjustment based on the variation in the magnetic flux linkage, a d-axis inductance of the electric motor, and a q-axis inductance of the electric motor.

8. An electric motor control method for a vehicle, comprising:
based on a motor torque request for an electric motor of the vehicle, generating a first d-axis current command for an electric motor of the vehicle and a first q-axis current command for the electric motor;
based on a speed of a rotor of the electric motor and the motor torque request, selectively determining at least one of a d-axis current adjustment and a q-axis current adjustment based on a temperature of the rotor of the electric motor;
producing a second d-axis current command for the electric motor by adjusting the first d-axis current command based on the d-axis current adjustment;
producing a second q-axis current command for the electric motor by adjusting the first q-axis current command based on the q-axis current adjustment; and
based on the second d-axis current command and the second q-axis current command, controlling switching of an inverter module and applying power to stator windings of the electric motor from an energy storage device,
wherein:
selectively determining at least one of the d-axis current adjustment and the q-axis current adjustment includes:
when the speed is greater than a predetermined speed, setting both the d-axis current adjustment and the q-axis current adjustment to a predetermined value; and
when the speed is less than the predetermined speed, based on whether the motor torque request is greater than a predetermined torque, selectively determining one of the d-axis current adjustment and the q-axis current adjustment based on the temperature of the rotor of the electric motor; and

producing the second d-axis current command includes, based on the d-axis current adjustment being equal to the predetermined value, setting the second d-axis current command equal to the first d-axis current command; and
producing the second q-axis current command includes, based on the q-axis current adjustment being equal to the predetermined value, setting the second q-axis current command equal to the first q-axis current command, and

wherein:
one of:
producing the second d-axis current command includes setting the second d-axis current command equal to the first d-axis current command plus the d-axis current adjustment; and
producing the second d-axis current command includes setting the second d-axis current command equal to the first d-axis current command multiplied by the d-axis current adjustment; and

one of:
producing the second q-axis current command includes setting the second q-axis current command equal to the first q-

Assignees

• Gm Global Tech Operations Llc

Inventors

• Yoo Anno
• Son Yo Chan
• Kwak Sangyeop

Classifications

• B60L11/1803

  Operations & Transport · mapped topic

• B60L2240/423

  Torque · CPC title

• H02P21/24 Primary

  Vector control not involving the use of rotor position or rotor speed sensors · CPC title

• B60L2260/56

  Temperature prediction, e.g. for pre-cooling · CPC title

• H02P21/14

  Estimation or adaptation of machine parameters, e.g. flux, current or voltage · CPC title