Optimized regenerative braking control of electric motors using look-up tables

Patent metadata

Field	Value
Publication number	US-11479124-B2
Application number	US-202117352436-A
Country	US
Kind code	B2
Filing date	Jun 21, 2021
Priority date	Nov 11, 2015
Publication date	Oct 25, 2022
Grant date	Oct 25, 2022

Abstract

A regenerative braking controller for an AC motor. To determine an electromagnetic torque for slowing or stopping the motor, the regenerative braking controller accesses a lookup table to retrieve a braking torque value corresponding to a current estimate of rotor velocity. The retrieved braking torque may correspond to a maximum or minimum torque level at which regenerative braking will occur at the current rotor velocity, or to a torque level at which charging current during regenerative braking will be maximized. If an external mechanical brake is present, the regenerative braking controller can forward an external braking torque signal to a controller so that the mechanical brake can apply the remainder of the braking force beyond that indicated by the regenerative braking torque. A method for establishing the braking torques to be stored in the lookup table is also disclosed.

First claim

What is claimed is:

1. A device comprising:
a look-up-table memory configured to store a regenerative braking table that includes a set of regenerative braking torque values over a range of rotor speeds of a motor;
a processing resource coupled to the look-up-table memory; and
a non-transitory memory coupled to the processing resource and storing instructions that, when executed, cause the processing resource to:
receive a desired rotor speed of the motor;
determine a current rotor speed of the motor;
determine a first torque value based on a difference between the current rotor speed and the desired rotor speed;
provide a set of data signals configured to control the motor based on the first torque value; and
when the first torque value represents a braking torque:
determine a regenerative braking torque based on the regenerative braking table and the current rotor speed; and
provide the set of data signals configured to control the motor to produce regenerative braking up to the regenerative braking torque.

2. The device of claim 1 , wherein:
the processing resource is configured to couple to an external brake; and
the non-transitory memory stores instructions that cause the processing resource to control the external brake to provide braking of the motor based on whether the first torque value exceeds the regenerative braking torque.

3. The device of claim 1 , wherein the regenerative braking table includes a set of maximum regenerative braking torque values and a set of minimum regenerative braking torque values over the range of rotor speeds.

4. The device of claim 1 , wherein the regenerative braking table includes a set of optimum regenerative braking torque values over the range of rotor speeds at which charging current is maximized.

5. The device of claim 1 further comprising:
a pulse-width modulation driver coupled to the processing resource and configured to:
receive the set of data signals; and
provide, based on the set of data signals, a set of pulse-width-modulation control signals configured to control the motor; and

a power driver circuit coupled to the pulse-width modulation driver and configured to:
receive the set of pulse-width-modulation control signals; and
provide, based on the set of data signals, a set of pulse-width-modulation pulses configured to control the motor.

6. The device of claim 5 further comprising a three-phase inverter coupled to the power driver circuit and configured to couple to the motor, wherein the three-phase inverter is configured to:
receive the set of pulse-width-modulation pulses; and
drive the motor according to the set of pulse-width-modulation pulses.

7. The device of claim 6 further comprising a battery management circuit coupled to the three-phase inverter and configured to couple to an energy storage system, wherein the battery management circuit is configured to perform regenerative braking by providing a charging current to the energy storage system.

8. The device of claim 1 further comprising:
a first analog-to-digital converter coupled to the processing resource and configured to couple to the motor to provide a motor current measurement to the processing resource;
a second analog-to-digital converter coupled to the processing resource and configured to couple to the motor to provide a motor voltage measurement to the processing resource; and
a third analog-to-digital converter coupled to the processing resource and configured to couple to the motor to provide a bus voltage measurement to the processing resource, wherein the non-transitory memory stores instructions that cause the processing resource to determine the current rotor speed of the motor based on the motor current measurement, the motor voltage measurement, and the bus voltage measurement.

9. The device of claim 8 , wherein the instructions that cause the processing resource to determine the current rotor speed of the motor based on the motor current measurement, the motor voltage measurement, and the bus voltage measurement include instructions to perform a Clarke transform and a Park transform on each of the motor current measurement and the motor voltage measurement.

10. The device of claim 1 , wherein the non-transitory memory stores further instructions that cause the processing resource to:
determine whether the current rotor speed is above a minimum regenerative braking rotor speed; and
provide the set of data signals configured to control the motor to produce regenerative braking up to the regenerative braking torque based on the current rotor speed being above the minimum regenerative braking rotor speed.

11. The device of claim 1 , wherein the instructions to determine the regenerative braking torque include instructions that cause the processing resource to:
retrieve, from the regenerative braking table, a first regenerative braking torque value associated with a first rotor speed and a second regenerative braking torque value associated with a second rotor speed such that the current rotor speed is between the first rotor speed and the second rotor speed; and
perform interpolation on the first regenerative braking torque value and the second regenerative braking torque value to determine the regenerative braking torque.

12. A method comprising:
receiving a regenerative braking table that includes a set of regenerative braking torque values over a range of rotor speeds of a motor;
receiving a desired rotor speed of the motor;
determining a current rotor speed of the motor;
determining a regenerative braking torque based on the regenerative braking table and the current rotor speed;
determining a first torque value based on a difference between the current rotor speed and the desired rotor speed;
providing a set of data signals configured to control the motor to transition from the current rotor speed to the desired rotor speed based on the first torque value, wherein the set of data signals are configured to control the motor to produce regenerative braking according to the first torque value up to the regenerative braking torque.

13. The method of claim 12 further comprising:
causing an external brake to brake the motor based on the first torque value exceeding the regenerative braking torque.

14. The method of claim 12 , wherein the regenerative braking table includes a set of maximum regenerative braking torque values and a set of minimum regenerative braking torque values over the range of rotor speeds.

15. The method of claim 12 , wherein the regenerative braking table includes a set of optimum regenerative braking torque values over the range of rotor speeds at which charging current is maximized.

16. The method of claim 12 further comprising providing, by a power driver circuit, a set of pulse-width-modulation pulses based on the set of data signals to control the motor.

17. The method of claim 16 further comprising:
receiving the set of pulse-width-modulation pulses by a three-phase inverter; and
driving the motor by the three-phase inverter according to the set of pulse-width-modulation pulses.

18. The method of claim 12 further comprising receiving a motor current measurement, a motor voltage measurement, and a bus voltage measurement, wherein the determining of the current speed of the motor is based on the motor current measurement, the motor voltage measurement, and the bus voltage measurement.

19. The method of claim 18 , wherein the determining of the current rotor speed includes performing a Clarke transform and a Park transf

Assignees

• Texas Instruments Inc

Inventors

• Murthy Aravind Samba
• Magee David Patrick

Classifications

• B60L2240/421

  Speed · CPC title

• H02P3/16

  by combined electrical and mechanical braking · CPC title

• B60L2240/423

  Torque · CPC title

• B60L15/025

  using field orientation; Vector control; Direct Torque Control [DTC] · CPC title

• H02P6/24 Primary

  Arrangements for stopping · CPC title