Normalization of motor phase measurements

Patent metadata

Field	Value
Publication number	US-9912275-B2
Application number	US-201615250337-A
Country	US
Kind code	B2
Filing date	Aug 29, 2016
Priority date	Sep 24, 2014
Publication date	Mar 6, 2018
Grant date	Mar 6, 2018

Abstract

A method of normalizing phase measurements for a motor using a normalizing phase measurements (NPM) algorithm that a processor implements to cause a motor controller coupled to stator terminals of the phases to execute forcing a set of input current or voltage vectors (set of input vectors) including repeating the forcing after rotating the rotor through a full mechanical cycle to generate resulting current or voltage samples (resulting samples) of non-normalized phase A and phase B waveforms. The magnitude of the input vectors are sufficiently small to not move the rotor. A maximum value (x_max) and a minimum value (x_min) are determined for each of the non-normalized phase A and phase B waveforms. An offset value and normalization scale factor (NSF) are determined from the max and min values. The offsets and NSFs are applied to the non-normalized phase waveforms to generate normalized phase A and phase B waveforms.

First claim

The invention claimed is:

1. A method of normalizing phase measurements for controlling an N-phase motor comprising:
applying a set of input voltage vectors to stator terminals of terminal windings of the N-phase motor;
rotating a rotor of the N-phase motor through discrete angles to complete at least one full mechanical cycle;
wherein rotating the rotor generates voltage samples of non-normalized phase A waveforms and voltage samples of non-normalized phase B waveforms;
wherein a magnitude of the input voltage vectors does not move the rotor;
wherein a time duration for the input voltage vectors is constant; and
applying the offset value and normalization scale factor (NSF) to each of the non-normalized phase A and phase B waveforms to generate a normalized phase A waveform and a normalized phase B waveform.

2. The method of claim 1 further including determining a maximum value (x_max) and a minimum value (x_min) for each of the non-normalized phase A waveforms and the non-normalized phase B waveforms.

3. The method of claim 2 further including determining the offset value and the normalization scale factor for each of the non-normalized phase A and the phase B waveforms from the maximum value and the minimum value for each of the non-normalized phase A waveforms and the non-normalized phase B waveforms.

4. The method of claim 1 , wherein said at least one full mechanical cycle comprises at least one electrical cycle.

5. The method of claim 1 , wherein said motor is a permanent magnet (PM) motor.

6. The method of claim 1 , wherein said motor is an AC (alternating current) induction motor.

7. The method of claim 1 , wherein said set of input vectors are all fundamental vectors.

8. A microcontroller unit (MCU) chip, comprising:
an analog-to-digital converter (ADC) for receiving N-phase measurements from voltage measurement circuits coupled to stator windings of a motor associated with each of said N-phases;
a pulse-width modulation (PWM) driver;
a SIG GEN block for applying a set of input voltage vectors to stator terminals of the stator;
wherein a magnitude of the input voltage vectors do not move a rotor in the motor;
wherein a time duration for the input voltage vectors is constant;
a processor for determining a maximum value (x_max) and a minimum value (x_min) for each of non-normalized phase A waveforms and for each of non-normalized phase B waveforms and using the x_max and the x_min for determining an offset value and normalization scale factor for each of the non-normalized phase A and the phase B waveforms;
wherein the processor applies the offset and the normalization scale factor to the non-normalized phase A and phase B waveforms to generate a normalized phase A waveform and a normalized phase B waveform, and
wherein the processor determines an angular position of the rotor using the normalized phase A waveform and the normalized phase B waveform.

Assignees

• Texas Instruments Inc

Inventors

• Thomas Eric James
• Magee David Patrick

Classifications

• H02P25/08

  Reluctance motors · CPC title

• H02P27/08

  with pulse width modulation · CPC title

• H02P21/18 Primary

  Estimation of position or speed · CPC title

• H02P21/24

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

• H02P25/03

  with brushless excitation · CPC title