Multi-objective optimization for active power management of synchronous motor drives

Patent metadata

Field	Value
Publication number	US-11938918-B2
Application number	US-202117496241-A
Country	US
Kind code	B2
Filing date	Oct 7, 2021
Priority date	Oct 7, 2020
Publication date	Mar 26, 2024
Grant date	Mar 26, 2024

Abstract

A method of controlling operation of an electric machine includes: determining a voltage-based torque limit based on a voltage constraint of a direct current (DC) bus supplying power to an inverter for powering the electric machine; determining a motor current-based torque limit based on a motor current limit; determining a supply current-based torque limit based on a supply rating, to supply current to the inverter, of the DC bus; determining a regenerative current-based torque limit based on a receive rating, to receive current from the inverter, of the DC bus; determining a final torque limit based on the voltage-based torque limit, the motor current-based torque limit, the supply current-based torque limit, and the regenerative current-based torque limit; determining a limited command torque based on a torque command and the final torque limit; and calculating at least one current command based on, at least, the limited command torque.

First claim

What is claimed is:

1. A method of controlling operation of an electric machine, comprising:
determining a voltage-based torque limit based on a voltage constraint of a direct current (DC) bus supplying power to an inverter for powering the electric machine;
determining a motor current-based torque limit based on a motor current limit;
determining a supply current-based torque limit based on a supply rating, to supply current to the inverter, of the DC bus;
determining a regenerative current-based torque limit based on a receive rating, to receive current from the inverter, of the DC bus;
determining a final torque limit based on the voltage-based torque limit, the motor current-based torque limit, the supply current-based torque limit, and the regenerative current-based torque limit;
determining a limited command torque based on a torque command and the final torque limit; and
calculating at least one current command based on, at least, the limited command torque.

2. The method of claim 1 , further comprising selectively controlling a plurality of switches within the inverter to cause the inverter to supply a current to the electric machine based on the at least one current command.

3. The method of claim 1 , wherein the motor current limit is a lesser one of a current limit of the electric machine and a current limit of the inverter.

4. The method of claim 1 , wherein determining the final torque limit further comprises arbitrating between the voltage-based torque limit and the motor current-based torque limit.

5. The method of claim 4 , wherein arbitrating between the voltage-based torque limit and the motor current-based torque limit further comprises:
determining a first motor current-based q-axis current corresponding to a d-axis current having a predetermined minimum value and corresponding to the motor current limit;
determining a second motor current-based q-axis current corresponding to the d-axis current having a predetermined maximum value and corresponding to the motor current limit;
determining a first voltage limit-based q-axis current corresponding to a d-axis current having a predetermined minimum value and corresponding to the voltage constraint of the DC bus;
determining a second voltage limit-based q-axis current corresponding to the d-axis current having a predetermined maximum value and corresponding to the voltage constraint of the DC bus;
determining one of the first motor current-based q-axis current and the first voltage limit-based q-axis current having a lesser value;
determining one of the second motor current-based q-axis current and the second voltage limit-based q-axis current having a lesser value; and
selecting one of the motor current-based torque limit and the voltage-based torque limit based on the one of the first motor current-based q-axis current and the first voltage limit-based q-axis current having the lesser value and based on the one of the second motor current-based q-axis current and the second voltage limit-based q-axis current having the lesser value.

6. The method of claim 5 , wherein selecting the one of the motor current-based torque limit and the voltage-based torque limit further comprises:
selecting the motor current-based torque limit as the final torque limit in response to determining the first motor current-based q-axis current being less than the first voltage limit-based q-axis current, and the second motor current-based q-axis current being less than the second voltage limit-based q-axis current; and
selecting the voltage-based torque limit as the final torque limit in response to determining the first voltage limit-based q-axis current being less than the first motor current-based q-axis current, and the second voltage limit-based q-axis current being less than the second motor current-based q-axis current.

7. The method of claim 4 , wherein arbitrating between the voltage-based torque limit and the motor current-based torque limit further comprises:
determining a first motor current-based q-axis current corresponding to a d-axis current having a predetermined minimum value and corresponding to the motor current limit;
determining a second motor current-based q-axis current corresponding to the d-axis current having a predetermined maximum value and corresponding to the motor current limit;
determining a first voltage limit-based q-axis current corresponding to a d-axis current having a predetermined minimum value and corresponding to the voltage constraint of the DC bus;
determining a second voltage limit-based q-axis current corresponding to the d-axis current having a predetermined maximum value and corresponding to the voltage constraint of the DC bus;
determining one of the first motor current-based q-axis current and the first voltage limit-based q-axis current having a lesser value;
determining one of the second motor current-based q-axis current and the second voltage limit-based q-axis current having a lesser value;
determining the one of the second motor current-based q-axis current and the second voltage limit-based q-axis current having the lesser value corresponding to a different constraint from the one of the first motor current-based q-axis current and the first voltage limit-based q-axis current having the lesser value;
determining a d-axis intersection current value where a q-axis current corresponding to the motor current limit is equal to a q-axis current corresponding to the voltage constraint of the DC bus; and
determining the final torque limit based on the d-axis intersection current value and based on the q-axis current corresponding to each of motor current limit and the voltage constraint of the DC bus.

8. The method of claim 1 , wherein determining the regenerative current-based torque limit includes determining a regenerative current and motor current-based torque limit based on an intersection of d-axis and q-axis currents to satisfy each of the receive rating and the motor current limit.

9. The method of claim 8 , further comprising:
calculating a voltage generated by the inverter based on the regenerative current and motor current-based current limit; and
determining if the voltage generated by the inverter based on the regenerative current and motor current-based current limit satisfies the voltage constraint of the DC bus to verify the intersection of d-axis and q-axis currents to satisfy each of the receive rating and the motor current limit.

10. The method of claim 1 , further comprising:
calculating a first y-intercept of a plot of d-axis current versus q-axis current, with the d-axis current and the q-axis current each corresponding to the inverter satisfying the receive rating;
calculating a second y-intercept of the plot of d-axis current versus q-axis current, with the d-axis current and the q-axis current each corresponding to the inverter satisfying the receive rating; and
determining if the electric machine can be operated in an a regenerative mode while satisfying the motor current limit, including, based on a velocity of the electric machine, one of:
determining if the motor current limit is greater than the first y-intercept of the plot of d-axis current versus q-axis current, and the first y-intercept of the plot of d-axis current versus q-axis current is greater than a negation of the motor current limit, and the negation of the motor current limit is greater than the second y-intercept of the plot of d-axis current versus q-axis current; and
determining if: the motor current limit is less than the first y-intercept of the plot of d-axis current versus q-axis current, and the motor current limit is greater than the second y-intercept of the plot of d-axis current versus q-a

Assignees

• Steering Solutions Ip Holding

Inventors

• Shah Nakul
• Pramod Prerit
• Namburi Krishna Mpk

Classifications

• B60W10/08 Primary

  including control of electric propulsion units, e.g. motors or generators · CPC title

• B60L15/20 Primary

  for control of the vehicle or its driving motor to achieve a desired performance, e.g. speed, torque, programmed variation of speed · CPC title

• B60L2240/423

  Torque · CPC title

• B60W2710/083

  Torque · CPC title

• Y02T10/64

  Electric machine technologies in electromobility · CPC title