# US 2014/0152204 A1 · Magnetic pole position detector for synchronous motor

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- Number: US 2014/0152204 A1
- Document ID: US20140152204A1
- Status: Published application
- Kind: A1
- Application number: 14/089,111
- Filed: 2013-11-25
- Published: 2014-06-05
- Earliest claimed: 2012-12-03
- Assignees: Fanuc Corporation
- Applicants: Fanuc Corporation
- Inventors: Naoto Sonoda; Yukio Toyozawa
- Web page: https://patentgrep.com/patent/US20140152204A1

## CPC

- H02P 21/32: Determining the initial rotor position (H02P21/34 takes precedence)
- H02P 21/34: Arrangements for starting
- H02P 2203/03: Determination of the rotor position, e.g. initial rotor position, during standstill or low speed operation
- H02P 2203/11: Determination or estimation of the rotor position or other motor parameters based on the analysis of high-frequency signals
- H02P: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS

## Abstract

A magnetic pole position detector includes, a voltage command unit that generates high-frequency voltage command in a dq coordinate system, a three-phase transformation unit that transforms the high-frequency voltage command in the dq coordinate system to high-frequency voltage command in a three-phase coordinate system by using an estimated magnetic pole position, a current detection unit that detects three-phase current fed from a power converter for generating drive power, a dq transformation unit that transforms the detected three-phase current to current in the dq coordinate system by using the estimated magnetic pole position, an estimated magnetic pole position calculation unit that calculates a new estimated magnetic pole position to be used in three-phase dq transformations, and a magnetic pole position confirmation unit that confirms that, when converging on a certain position, the estimated magnetic pole position is the magnetic pole position at the time when the synchronous motor is started.

## Claims

### Claim 1

A magnetic pole position detector for detecting a magnetic pole position when a synchronous motor is started, the magnetic pole position detector comprising:
a voltage command unit that generates high-frequency voltage command in a dq coordinate system;
a three-phase coordinate transformation unit that transforms the high-frequency voltage command in the dq coordinate system to high-frequency voltage command in a three-phase coordinate system by using an estimated magnetic pole position;
a current detection unit that detects three-phase current fed from a power converter to the synchronous motor, the power converter generating drive power for the synchronous motor in accordance with the high-frequency voltage command in the three-phase coordinate system;
a dq-coordinate transformation unit that transforms the three-phase current detected by the current detection unit to current in the dq coordinate system by using the estimated magnetic pole position used in a transformation by the three-phase coordinate transformation unit;
an estimated magnetic pole position calculation unit that calculates a new estimated magnetic pole position to be used in a coordinate transformation process by each of the three-phase coordinate transformation unit and the dq-coordinate transformation unit, in accordance with the current in the dq coordinate system and the high-frequency voltage command in the dq coordinate system; and
a magnetic pole position confirmation unit that confirms that, when the estimated magnetic pole position calculated by the estimated magnetic pole position calculation unit substantially converges on a certain position, the estimated magnetic pole position is the magnetic pole position when the synchronous motor is started.

### Claim 2 (depends on 1)

The magnetic pole position detector according to claim 1, wherein
the high-frequency voltage command in the dq coordinate system include a d-phase component that is a high frequency and a q-phase component that has zero amplitude, and
the estimated magnetic pole position calculation unit calculates the new estimated magnetic pole position to be used, on the basis of a q-phase component of the current in the dq coordinate system and the d-phase component that is a high frequency.

### Claim 3 (depends on 1)

The magnetic pole position detector according to claim 1, wherein the estimated magnetic pole position calculation unit includes:
a differentiation unit that differentiates a value of the current in the dq coordinate system;
a product calculation unit that calculates a product of the value of current differentiated by the differentiation unit and the high-frequency voltage command in the dq coordinate system;
a filtering unit that removes a high-frequency component from the product obtained by the product calculation unit;
a gain unit that calculates a product of a predetermined gain constant and a signal output by the filtering unit after the removal of the high-frequency component; and
an integration unit that integrates the product output from the gain unit and then outputs an integrated result as the new estimated magnetic pole position to be used.

### Claim 4 (depends on 1)

The magnetic pole position detector according to claim 1, wherein the estimated magnetic pole position calculation unit includes:
a phase shifting unit that shift a phase of the high-frequency voltage command in the dq coordinate system;
a product calculation unit that calculates a product of a value of the current in the dq coordinate system and the high-frequency voltage command whose phase is shifted by the phase shifting unit;
a filtering unit that removes a high-frequency component from the product obtained by the product calculation unit;
a gain unit that calculates a product of a predetermined gain constant and a signal output by the filtering unit after the removal of the high-frequency component; and
an integration unit that integrates the product output from the gain unit and then outputs an integrated result as the new estimated magnetic pole position to be used.