Stator resistance estimation for electric motors

Patent metadata

Field	Value
Publication number	US-9413282-B2
Application number	US-201414486303-A
Country	US
Kind code	B2
Filing date	Sep 15, 2014
Priority date	Oct 3, 2013
Publication date	Aug 9, 2016
Grant date	Aug 9, 2016

Abstract

A method of controlling an electric motor (motor) includes providing a processor having an associated memory storing a stator resistance (Rs) estimation (RSE) algorithm that is programmed to implement the RSE algorithm to execute steps including injecting a current waveform at an arbitrary frame of reference into the stator using a field-oriented-control (FOC) motor controller including an Id controller and an Iq controller, and measuring current and voltage values from the motor responsive to the injecting. The measured current and voltage values are then transformed into transformed current and voltage values in a d/q coordinate system. The transformed current and voltage values are low pass filtered to generate filtered d/q current and voltage values, and a value for Rs is estimated from the filtered d/q current and voltage values. The arbitrary frame of reference can be a time-varying frame of reference.

First claim

The invention claimed is:

1. A method of controlling an electric motor (motor), including a rotor and a stator, comprising:
providing a processor having an associated memory storing a stator resistance (Rs) estimation (RSE) algorithm, said processor programmed to implement said RSE algorithm to execute:
injecting a current waveform at an arbitrary frame of reference into said stator using a field-oriented-control motor controller (FOC controller) including an Id controller for controlling direct (d) current and an Iq controller for controlling quadrature (q) current;
measuring current and voltage values from said motor responsive to said injecting;
transforming said measured current and voltage values into transformed current and voltage values in d/q coordinate system;
low pass filtering said transformed current and voltage values to generate filtered d/q current and voltage values, and

estimating a value for said Rs ({circumflex over (R)} s ) from said filtered d/q current and voltage values;
wherein said arbitrary frame of reference is a time-varying frame of reference, further comprising providing said filtered d/q current values to said FOC controller in said d/q coordinate system as:

[

i
d

i
q

]

=

[

I
mag

⁢

cos
⁡

(

(

θ
r

-
θ

)

)

-

I
mag

⁢

sin
⁡

(

(

θ
r

-
θ

)

)

]

.

2. A method of controlling an electric motor (motor), including a rotor and a stator, comprising:
providing a processor having an associated memory storing a stator resistance (Rs) estimation (RSE) algorithm, said processor programmed to implement said RSE algorithm to execute:
injecting a current waveform at an arbitrary frame of reference into said stator using a field-oriented-control motor controller (FOC controller) including an Id controller for controlling direct (d) current and an Iq controller for controlling quadrature (q) current;
measuring current and voltage values from said motor responsive to said injecting;
transforming said measured current and voltage values into transformed current and voltage values in d/q coordinate system;
low pass filtering said transformed current and voltage values to generate filtered d/q current and voltage values, and

estimating a value for said Rs ({circumflex over (R)} s ) from said filtered d/q current and voltage values;
further comprising coupling said {circumflex over (R)} s to an estimator block having an output coupled to an input of a speed controller that controls a speed of said motor.

3. A method of controlling an electric motor (motor), including a rotor and a stator, comprising:
providing a processor having an associated memory storing a stator resistance (Rs) estimation (RSE) algorithm, said processor programmed to implement said RSE algorithm to execute:
injecting a current waveform at an arbitrary frame of reference into said stator using a field-oriented-control motor controller (FOC controller) including an Id controller for controlling direct (d) current and an Iq controller for controlling quadrature (q) current;
measuring current and voltage values from said motor responsive to said injecting;
transforming said measured current and voltage values into transformed current and voltage values in d/q coordinate system;
low pass filtering said transformed current and voltage values to generate filtered d/q current and voltage values, and

estimating a value for said Rs ({circumflex over (R)} s ) from said filtered d/q current and voltage values;
wherein said Id controller and said Iq controller are coupled to receive said {circumflex over (R)} s as inputs, and wherein each of said Id controller and said Iq controller include an automatic gain adjustment algorithm configured to adjust an open loop gain as a function of said {circumflex over (R)} s so that as said {circumflex over (R)} s changes said open loop gain is changed to reduce a change in their open loop bandwidth during operation of said motor.

4. A microcontroller unit (MCU) chip, comprising:
a substrate having the following formed in or thereon configured to realize a field-oriented-control (FOC) motor controller (FOC controller) including:
at least one analog-to-digital converter (ADC);
a pulse-width modulation (PWM) driver;
a first non-volatile program memory including a stator resistance (Rs) estimation (RSE) algorithm for an electric motor (motor) stored therein;
an Id controller for controlling direct (d) current and an Iq controller for controlling quadrature (q) current;
a digital I/O (interface);
a central processing unit (CPU);
a clock, and

a digital data bus and an address bus for coupling together said ADC, said first non-volatile program memory, said digital I/O (interface), said CPU, and said clock,
wherein said CPU implements said RSE algorithm which executes:
triggering injecting a current waveform at an arbitrary frame of reference into a stator of said motor using said FOC controller coupled to drive said PWM driver;
transforming received measured current and voltage values from said motor responsive to said injecting into transformed d/q current and voltage values in a d/q coordinate system;
low pass filtering said tra

Assignees

• Texas Instruments Inc

Inventors

• Magee David Patrick
• VELTMAN ANDRé
• Zambada Jorge

Classifications

• H02P21/24

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

• H02P21/14 Primary

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