Rotor position sensing system for permanent magnet synchronous motors and related methods

Patent metadata

Field	Value
Publication number	US-9876452-B1
Application number	US-201615382160-A
Country	US
Kind code	B1
Filing date	Dec 16, 2016
Priority date	Dec 16, 2016
Publication date	Jan 23, 2018
Grant date	Jan 23, 2018

Abstract

Implementations of a system for sensing rotor position of a PMSM may include: a controller which may be coupled with the PMSM. The controller may be configured to apply a plurality of voltage vectors to the PMSM to generate a plurality of sensing signals from a stator of the PMSM in response. A comparator may be coupled to the PMSM configured to receive and to compare each one of the plurality of sensing signals with a threshold voltage. A rise time measurement circuit may calculate a plurality of rise times using the plurality of sensing signals in response to receiving a signal from the comparator. The rotor-angle estimation circuit may be configured to identify from the plurality of rise times a shortest rise time and a voltage vector corresponding with the shortest rise time and thereby identify the position of the rotor of the PMSM.

First claim

What is claimed is:

1. A system for sensing rotor position of a permanent magnet synchronous motor, comprising:
a controller configured to couple with a permanent magnet synchronous motor (PMSM), wherein the controller is configured to apply a plurality of voltage vectors to a PMSM to generate a plurality of sensing current signals from a stator of the PMSM in response;
a resistor configured to couple to the stator of the PMSM, wherein the resistor is configured to receive the plurality of sensing current signals and is configured to generate a corresponding plurality of sensing voltage signals;
an amplifier coupled to the resistor, wherein the amplifier is configured to receive and to amplify the plurality of the sensing voltage signals;
a comparator coupled to the amplifier and to a threshold voltage generator, wherein the comparator is configured to receive and to compare each one of the plurality of amplified sensing voltage signals with a threshold voltage generated by the threshold voltage generator;
a rise time measurement circuit coupled to the comparator, wherein the rise time measurement circuit is configured to calculate a plurality of rise times using the plurality of amplified sensing voltage signals in response to receiving a signal from the comparator;
a memory coupled with the rise time measurement circuit, wherein the memory is configured to store the plurality of rise times; and
a rotor-angle estimation circuit coupled with the memory, wherein the rotor-angle estimation circuit is configured to:
identify from the plurality of rise times a shortest rise time and a voltage vector corresponding with the shortest rise time;
identify at least two adjacent voltage vectors to the voltage vector with the shortest rise time;
one of average, sum, and weighted sum the rise times of the voltage vector corresponding with the shortest rise time and its at least two adjacent voltage vectors to form one of an average first rise time value, a summed first rise time value, and a weighted summed first rise time value, respectively;
identify the voltage vector that is 180 degrees out of phase with the voltage vector corresponding to the shortest rise time;
identify at least two adjacent voltage vectors to the voltage vector that is 180 degrees out of phase;
one of average, sum, and weighted sum the rise times of the voltage vector that is 180 degrees out of phase and its at least two adjacent voltage vectors to form one of a second average rise time value, a summed second rise time value, and a weighted summed second rise time value, respectively;
calculate a rotor position relative to the stator of the PMSM through identifying one of a lowest average rise time, a lowest summed rise time, and a lowest weighted summed rise time using one of the corresponding pair of the first average rise time value, the second average rise time value, the summed first rise time value, the summed second rise time value, the weighted summed first rise time value, and the weighted summed second rise time value, respectively.

2. The system of claim 1 , wherein the threshold voltage generator is coupled to the controller and is configured to generate the threshold voltage in response to a command from the controller, wherein the threshold voltage is one of a first threshold voltage and a second threshold voltage.

3. The system of claim 2 , wherein the first threshold voltage and the second threshold voltage are calculated using one of a first threshold voltage equation and a second threshold voltage equation;
wherein the first threshold voltage equation is
V th1 =( G )( R sh )( I th1 )+ V off

and the second threshold voltage equation is
V th2 =( G )( R sh )( I th2 )+ V off

where V th1 is the first threshold voltage, V th2 is the second threshold voltage, G is a gain of the amplifier, R sh is a resistance from the resistor, I th1 is a first threshold current, I th2 is a second threshold current, and V off is the amplifier's offset voltage.

4. The system of claim 3 , wherein the first threshold current and the second threshold current are related by the equation

I

th
⁢

⁢
1

=

4
3

⁢

I

th
⁢

⁢
2

.

5. The system of claim 1 , wherein the plurality of voltage vectors is one of 12 and 24.

6. A system for sensing rotor position of a permanent magnet synchronous motor, comprising:
a controller configured to couple with a permanent magnet synchronous motor (PMSM), wherein the controller is configured to apply a plurality of voltage vectors to a stator of a PMSM which generates a plurality of sensing current signals from the stator of the PMSM in response to the plurality of voltage vectors;
an amplifier configured to couple to the PMSM, wherein the amplifier is configured to receive and to amplify the plurality of the sensing current signals;
an analog to digital (A/D) converter coupled to the amplifier, wherein the A/D converter is configured to convert the plurality of the sensing current signals into a plurality of digital current signals;
a rise time measurement circuit coupled to the A/D converter and to a controller, wherein the rise time measurement circuit is configured to calculate a plurality of rise times in response to receiving a plurality of digital current signals from the A/D converter and a threshold A/D value from the controller;
a memory coupled with the rise time measurement circuit, wherein the memory is configured to store the plurality of rise times; and
a rotor-angle estimation circuit coupled with the memory, wherein the rotor-angle estimation circuit is configured to:
identify from the plurality of rise times a shortest rise time and a voltage vector corresponding with the shortest rise time;
identify at least two adjacent voltage vectors to the voltage vector with the shortest rise time;
one of average, sum, and weighted sum the rise times of the voltage vector corresponding with the shortest rise time and its at least two adjacent voltage vectors to form one of an average first rise time value, a summed first rise time value, and a weighted summed first rise time value, respectively;
identifying the voltage vector that is 180 degrees out of phase with the voltage vector corresponding to the shortest rise time;
identify at least two adjacent voltage vectors to the voltage vector that is 180 degrees out of phase;
one of average, sum, and weighted sum the rise times of the voltage vector that is 180 degrees out of phase and its at least two adjacent voltage vectors to form one of a second average rise time value, a summed second rise time value, and a weighted summed second rise time value, respectively;
calculate a rotor position relative to the stator of the PMSM by determining one of a lowest average rise time, a lowest summed rise time, and a lowest weighted summed rise time using one of the corresponding pair of the first average rise time value, the second average rise time value, the summed first rise time value, the summed second rise time value, the weight

Assignees

• Semiconductor Components Ind Llc

Inventors

• Okubayashi Masanori

Classifications

• H02P2203/09

  Motor speed determination based on the current and/or voltage without using a tachogenerator or a physical encoder · CPC title

• H02P2203/03

  Determination of the rotor position, e.g. initial rotor position, during standstill or low speed operation · CPC title

• H02P21/22

  Current control, e.g. using a current control loop · CPC title

• H02P21/18 Primary

  Estimation of position or speed · CPC title

• H02P21/28

  Stator flux based control · CPC title