Regenerative braking controller for electric motors

Patent metadata

Field	Value
Publication number	US-9783063-B2
Application number	US-201514837810-A
Country	US
Kind code	B2
Filing date	Aug 27, 2015
Priority date	Aug 27, 2015
Publication date	Oct 10, 2017
Grant date	Oct 10, 2017

Abstract

A method of regenerative braking includes providing an electric motor including at least one stator and a rotor, a speed of the rotor, a motor controller that regulates a current level in the stator winding, a power inverter which controls an energy flow to the stator terminal, and an energy storage system (ESS) which exchanges energy with the motor. A battery management circuit is between the power inverter and the ESS, and a processor has an associated memory storing a regenerative braking (RB) algorithm. The RB algorithm during braking causes the motor controller to execute determining an RB torque value from the rotor speed that maximizes regenerative braking current, and the power inverter is used to redirect the RB current to maximize a power transfer from the motor to the ESS.

First claim

The invention claimed is:

1. A microcontroller unit (MCU) chip, comprising:
a substrate having the following formed thereon configured to realize a motor controller for controlling an N-phase electric motor (motor) comprising at least one stator having a winding (stator winding) with a stator terminal, and a rotor, including:
at least one analog-to-digital converter (ADC) for receiving resulting N-phase measurements from current measurement circuits or voltage measurement circuits coupled to said stator windings associated with each of said N-phases;
a pulse-width modulation (PWM) driver;
a central processing unit (CPU) coupled to a first non-volatile program memory including code for realizing a regenerative braking (RB) algorithm, a speed controller, an angular velocity estimator (EST) block, and a reference current generator block having an input coupled to receive an output from said ADC's, wherein said reference current generator block has respective inputs coupled to an output of said EST block and an output of said speed controller, an D-axis current controller for controlling direct (d) current and an Q-axis current controller for controlling quadrature (q) current having inputs coupled to an output of said reference current generator block and outputs coupled to said PWM driver through a space-vector generator (SVG) block;

a digital I/O (interface);
said CPU coupled through said digital I/O (interface) to receive said N-phase measurements after processing by said ADC's;
a clock, and a digital data bus and an address bus for coupling together said ADC's, said program memory, said digital I/O (interface), said CPU, and said clock,
wherein said RB algorithm utilizes a measured or estimated speed of said rotor (rotor speed) from said EST block during braking of said motor to cause said motor controller to execute:
determining a value for RB torque (RB torque value) from said rotor speed that maximizes a level of a RB current (maximum RB current), and
using a power inverter to redirect said maximum RB current to maximize a power transfer from said motor to an energy storage system (ESS) coupled to exchange energy with said motor by a battery management circuit coupled between said power inverter and said ESS.

2. The MCU chip of claim 1 , wherein said battery management circuit (controls said maximum RB current using a current regulation circuit based on a maximum charging current level supported by said ESS.

3. The MCU chip of claim 1 , wherein said motor includes an external brake, and said program memory further includes code for realizing an RB controller having an input coupled to receive a desired braking torque level (τ desired ) output by said speed controller, an external brake controller coupled to receive an external braking torque (τ ext ) output by said RB controller for coupling to drive said external brake,
said RB algorithm further including code for during braking of said motor to cause said motor controller to execute:
determining a value for said τ ext from said rotor speed to provide additional mechanical braking, and
decomposing said τ desired into two components wherein said motor controller applies said RB torque value as one torque component to provide said RB current and a second torque component provided by said external brake to said motor to meet said τ ext .

4. The MCU chip of claim 1 , wherein said motor comprises a permanent magnet (PM) motor and wherein said RB algorithm further includes code for computing said RB torque value (τ regen ) using:

τ
regen

=

-

(

K
b
2

2
⁢

R
s

)

⁢
ω

wherein said ω is said rotor speed, said K b is a back-EMF constant of said PM motor, and said R s is a resistance of said stator windings.

5. The MCU chip of claim 1 , wherein said program memory stores a table including a plurality of said RB torque values versus said rotor speed, and said RB algorithm further includes code for using said table for said determining said RB torque value in real-time.

6. The MCU chip of claim 1 , wherein said program memory stores a closed-form expression that relates said RB torque values with said maximum RB current that said RB algorithm has code for utilizing.

7. The MCU chip of claim 1 , wherein said motor controller implements field-oriented control (FOC).

Assignees

• Texas Instruments Inc

Inventors

• Murthy Aravind Samba
• Magee David Patrick

Classifications

• B60L7/14 Primary

  for vehicles propelled by AC motors · CPC title

• B60L11/1803

  Operations & Transport · mapped topic

• B60L7/26

  Controlling the braking effect · CPC title

• B60L2220/12

  Induction machines · CPC title

• Y02T10/64

  Electric machine technologies in electromobility · CPC title