# US 5,705,872 A · Brushless resolver

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- Number: US 5,705,872 A
- Document ID: US5705872A
- Status: Granted
- Kind: A
- Application number: 08/679,808
- Filed: 1996-07-15
- Granted: 1998-01-06
- Earliest claimed: 1995-07-25
- Assignees: Siemens Aktiengesellschaft
- Inventors: Hans Loge
- Web page: https://patentgrep.com/patent/US5705872A

## CPC

- G01D 5/2073: {by movement of a single coil with respect to two or more coils}
- H01F 38/18: Rotary transformers
- G01D: MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
- H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES

## Abstract

A brushless resolver having a stator and a rotor, and a resolver part axially displaced to one another and a transformer part and having associated windings is provided. An additional short-circuited winding arranged parallel with the transformer rotor winding with few turns on the iron core thereof is also provided. A lowpass filter is thereby formed, which compensates the unwanted frequency-dependent phase displacement between the input voltage and the output voltages for the respective frequency.

## Claims

### Claim 1

A brushless resolver having a stator and a rotor, comprising:
a resolver part having at least two stator windings and at least one rotor winding arranged on the stator and rotor;
a transformer part displaced axially relative to the resolver part, the transformer part having a transformer stator winding and a transformer rotor winding, each having a number of turns; and
a short-circuited winding arranged in the rotor as a wire winding parallel to the transformer rotor winding on an iron core thereof, wherein the short-circuited winding has a number of turns and a wire diameter selected so as to form a lowpass filter to compensate the phase displacement of the resolver at the operating frequency.

### Claim 2 (depends on 1)

The resolver according to claim 1, wherein the number of turns of the short-circuited winding is more than 1 and less than 1/4 of the number of turns of the transformer rotor winding.

### Claim 3 (depends on 2)

The resolver according to claim 2, wherein the diameter and the number of turns of the short-circuited winding compensate the phase displacement up to a remainder between 0.degree. and 10.degree..

### Claim 4 (depends on 1)

The resolver according to claim 1, wherein the short-circuited winding has a diameter and number of turns to compensate the phase displacement up to between 0.degree. and 10.degree..

### Claim 5 (depends on 1)

The resolver according to claim 1, wherein the short-circuited winding has a wire thickness equal to that of the transformer rotor winding.

### Claim 6 (depends on 1)

The resolver according to claim 1, wherein a transformation relation is held relatively constant through matching of the numbers of turns of the transformer part.

### Claim 7 (depends on 6)

The brushless resolver according to claim 6, wherein the short-circuited winding comprises means for compensating the phase displacement at an operating frequency so that the transformation relation has a relative maximum.