# US 8,542,085 B2 · High frequency rotary transformer for synchronous electrical machines

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- Number: US 8,542,085 B2
- Document ID: US8542085B2
- Status: Granted
- Kind: B2
- Application number: 13/036,652
- Filed: 2011-02-28
- Published: 2012-08-30
- Granted: 2013-09-24
- Earliest claimed: 2011-02-28
- Assignees: GM Global Technology Operations LLC
- Applicants: Constantin C. Stancu; Peter J. Savagian; Khwaja M. Rahman; Robert T. Dawsey; Erik Hatch
- Inventors: Constantin C. Stancu; Peter J. Savagian; Khwaja M. Rahman; Robert T. Dawsey; Erik Hatch
- Web page: https://patentgrep.com/patent/US8542085B2

## CPC

- H01F 38/18: Rotary transformers
- H01F: MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES

## Abstract

A high frequency rotary transformer for an electrical machine includes a primary transformer component having a primary transformer winding, and a secondary transformer component having a secondary transformer winding. The primary transformer winding is configured to be coupled to a DC power source via a DC to AC converter. The secondary transformer winding is configured to be coupled to a winding of the rotor. Each of the primary and secondary transformer components are mechanically coupled to either the stator or the rotor. The secondary transformer component is configured to rotate with respect to the primary transformer component to produce a magnetic flux via the primary transformer winding and the secondary transformer winding.

## Claims

### Claim 1

A high frequency rotary transformer for an electrical wound rotor synchronous machine having a stator and a rotor, the rotary transformer comprising:
a primary transformer component having a primary transformer winding, the primary transformer winding configured to be coupled to a DC power source; and
a secondary transformer component having a secondary transformer winding, the secondary transformer winding configured to be coupled to a winding of the rotor;
an AC-DC component interconnected between the secondary transformer component and the rotor,
wherein each of the primary and secondary transformer components are mechanically coupled to either the stator or the rotor; and
wherein the secondary transformer component is configured to rotate with respect to the primary transformer component to produce a magnetic flux via the primary transformer winding and the secondary transformer winding.

### Claim 2 (depends on 1)

The rotary transformer of claim 1, wherein the secondary transformer component is configured to rotate with respect to the primary transformer component to provide a transformer frequency greater than approximately 60 Hz.

### Claim 3 (depends on 1)

The rotary transformer of claim 1, wherein the primary transformer component and the secondary transformer component are separated by an axial gap.

### Claim 4 (depends on 3)

The rotary transformer of claim 3, wherein the primary transformer component is mechanically coupled to the stator, and the secondary transformer component is mechanically coupled to the rotor.

### Claim 5 (depends on 1)

The rotary transformer of claim 1, wherein the primary transformer component and the secondary transformer component are separated by a radial gap.

### Claim 6 (depends on 5)

The rotary transformer of claim 5, wherein the primary transformer component is mechanically coupled to the stator, and the secondary transformer component is mechanically coupled to the rotor.

### Claim 7 (depends on 6)

The rotary transformer of claim 6, wherein the secondary transformer component is nested within an inner diameter of a hub of the rotor.

### Claim 8 (depends on 1)

The rotary transformer of claim 1, further including a cooling liquid path provided within at least one of the primary transformer component and the secondary transformer component.

### Claim 9 (depends on 1)

The rotary transformer of claim 1, wherein the cooling liquid path is configured to accept automotive transmission oil.

### Claim 10

A rotary transformer power supply system comprising:
an inverter module configured to receive a DC input and a rotor current command;
a rotor having a rotor winding provided therein;
a rotary transformer, the rotary transformer comprising:
a primary transformer component having a primary transformer winding, the primary transformer winding configured to be coupled to the inverter module; and
a secondary transformer component having a secondary transformer winding coupled to the winding of the rotor;
an AC-DC component interconnected between the secondary transformer component and the rotor,
wherein each of the primary and secondary transformer components are mechanically coupled to either the stator or the rotor; and wherein the secondary transformer component is configured to rotate with respect to the primary transformer component to produce a magnetic flux via the primary transformer winding and the secondary transformer winding.

### Claim 11 (depends on 10)

The system of claim 10, wherein the primary transformer component and the secondary transformer component are separated by an axial gap.

### Claim 12 (depends on 11)

The system of claim 11, wherein the primary transformer component is mechanically coupled to the stator, and the secondary transformer component is mechanically coupled to the rotor.

### Claim 13 (depends on 10)

The system of claim 10, wherein the primary transformer component and the secondary transformer component are separated by a radial gap.

### Claim 14 (depends on 13)

The system of claim 13, wherein the primary transformer component is mechanically coupled to the stator, and the secondary transformer component is mechanically coupled to the rotor.

### Claim 15 (depends on 14)

The system of claim 14, wherein the secondary transformer component is nested within an inner diameter of a hub of the rotor.

### Claim 16 (depends on 10)

The system of claim 10, wherein the primary transformer winding and the secondary transformer winding are toroidal.

### Claim 17 (depends on 10)

The system of claim 10, wherein the secondary transformer component is configured to rotate with respect to the primary transformer component to provide a transformer frequency greater than approximately 60 Hz.

### Claim 18

A method of providing power to an electrical machine having a rotor and a stator, the method comprising:
receiving, at a high frequency rotary transformer, an AC signal indicative of a rotor current command;
coupling the AC signal through the high frequency rotary transformer by rotating a secondary winding of the high frequency rotary transformer with respect to a primary winding of the high frequency rotary component to produce a magnetic flux;
converting the coupled AC signal to a DC via an AC-DC component that is interconnected between the high frequency rotary transformer and the rotor winding;
providing the DC signal to a winding of the rotor.

### Claim 19 (depends on 18)

The method of claim 18, wherein the coupling includes rotating the secondary winding with respect to the primary winding such that the frequency of the high frequency rotary transformer is greater than approximately 60 Hz.