# US 6,297,975 B1 · Generalized method of paralleling voltage amplifiers

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- Number: US 6,297,975 B1
- Document ID: US6297975B1
- Status: Granted
- Kind: B1
- Application number: 09/329,759
- Filed: 1999-06-10
- Granted: 2001-10-02
- Earliest claimed: 1998-09-16
- Assignees: Crown Audio, Inc.
- Inventors: Gerald R. Stanley
- Web page: https://patentgrep.com/patent/US6297975B1

## CPC

- H02M 7/4807: {having a high frequency intermediate AC stage}
- H02M: APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF (transformers H01F; dynamo-electric converters H02K47/00; controlling transformers, reactors or choke coils, control or regulation of electric motors, generators or dynamo-electric converters H02P)

## Abstract

A generalized method for balancing paralleled power converters is disclosed wherein (N) power converters, generally voltage amplifiers, are parallel and have current sensors positioned so as to form a differencing equation for the circulating current, and use that difference current as feedback to the paralleled power converters to force the circulating current to zero. The current sensors are current transforming transducers, where (N−1) transducers are included and where the feedback from the (N−1) transducers is distributed to summing amplifiers, which according to their gain distribution, balances the power converters. The system also includes passive magnetic devices to facilitate current sharing, where the devices are generally inductors which are designed to store no magnetic energy when under balanced excitation.

## Claims

### Claim 1

A system of two or more (N) parallel joined power converters having outputs connected in parallel, comprising current sensors to directly measure the circulating currents and by use of negative feedback, regulate the circulating current to zero at a main output, wherein said negative feedback is produced by the circulating current being distributed between the parallel powered converters in such a manner as to sum to zero the combined correction signal injected into the main output signal, wherein said current sensors are DC responding current transducers based on magnetic flux sensing, wherein each of said power converters being paralleled is incident to the primary of the current transducers, wherein each current transducer primary has a number of primary turns, a total of the primary turns on each current transducer being zero when reversed polarity windings are counted as negative turns, wherein each power converter has an identical number of primary turns (M) on the current sensor except for one which has a counter poled winding of M*(N−1) turns.

### Claim 2

A system of two or more (N) parallel joined power converters having outputs connected in parallel, comprising current sensors to directly measure the circulating currents and by use of negative feedback, regulate the circulating current to zero at a main output, wherein said negative feedback is passed through summing amplifiers which distribute the feedback to said parallel joined power converters, wherein said summing amplifiers (N) input ports.

### Claim 3

A system of 3 or more (N) paralleled power converters having outputs connected in parallel, comprising passive magnetic devices to facilitate current sharing, said devices being designed to store no magnetic energy when under balanced excitation.

### Claim 4 (depends on 3)

The system of claim 3, wherein said passive magnetic devices are inductors.

### Claim 5 (depends on 4)

The system of claim 4, including (N−1) inductors.

### Claim 6 (depends on 5)

The system of claim 5, wherein each of the power converters has an identical number of primary turns (M) on an (N−1) inductor associated with the power converter except for one which has a counter poled winding of M*(N−1) turns.

### Claim 7

A system of two or more (N) parallel joined power converters having outputs connected in parallel, comprising current sensors to directly measure the circulating currents and regulate the circulating current to zero, and further comprising passive magnetic devices to facilitate current sharing, said devices being designed to store no magnetic energy when under balanced excitation.

### Claim 8 (depends on 7)

The system of claim 7, wherein the circulating currents are differenced, and negative feedback is provided to balance the power converters.

### Claim 9 (depends on 8)

The system of claim 8, wherein said negative feedback is produced by the circulating currents being distributed between the parallel power converters in such a manner as to sum to zero in a combined signal output.

### Claim 10 (depends on 8)

The system of claim 8 wherein said negative feedback is passed through summing amplifiers which distribute the feedback to said parallel joined power converters.

### Claim 11 (depends on 7)

The system of claim 7, including (N−1) current sensors.

### Claim 12 (depends on 7)

The system of claim 7, wherein said passive magnetic devices are (N−1) inductors.