# US 4,400,629 A · Delta-star connection

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- Number: US 4,400,629 A
- Document ID: US4400629A
- Status: Granted
- Kind: A
- Application number: 06/394,632
- Filed: 1982-07-02
- Granted: 1983-08-23
- Earliest claimed: 1981-07-31
- Assignees: Schaltbau Gesellschaft mbH
- Inventors: Ernst Kratzmair
- Web page: https://patentgrep.com/patent/US4400629A

## CPC

- G05F 1/44: semiconductor devices only
- H02M 5/14: for conversion between circuits of different phase number
- H03K 17/725: for AC voltages or currents (H03K17/722, H03K17/735 take precedence)
- G05F: SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
- 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)
- H03K: PULSE TECHNIQUE (measuring pulse characteristics G01R; modulating sinusoidal oscillations with pulses H03C; transmission of digital information H04L; discriminator circuits detecting phase difference between two signals by counting or integrating cycles of oscillation H03D3/04; automatic control, starting, synchronisation or stabilisation of generators of electronic oscillations or pulses where the type of generator is irrelevant or unspecified H03L; coding, decoding or code conversion, in general H03M)

## Abstract

A three-phase circuit, either load impedances or transformer windings for feeding such load impedances, are connected in a delta circuit configuration by a first group of controllable semiconductor elements and in a star circuit configuration by a second group of such elements. All elements are fired, but at different phase angles for operatively establishing a star, a delta, or a mixed type of connection.

## Claims

### Claim 1

A circuit for the selective connection of a three-phase load in a delta and a star circuit connection, comprising:
a first group of controllable semiconductor elements connected to said three-phase load for completing a delta circuit for the three-phase load;
a second group of controllable semiconductor elements connected to ends of the three-phase load for completing a star circuit for the three-phase load; and
control circuit means connected to the elements of said first and second groups and providing firing pulses to said elements for always operating both of said groups but with different firing delays.

### Claim 2 (depends on 1)

A circuit as in claim 1, said first group including three pairs of semiconductor elements, the elements of each pair being connected in phase opposition.

### Claim 3 (depends on 1, 2)

A circuit as in claim 1 or 2, said second group including six semiconductor elements, all having one terminal connected to a common junction.

### Claim 4 (depends on 1, 2)

A circuit as in claim 1 or 2, said second group including three pairs of semiconductor elements interconnected in a delta circuit.

### Claim 5 (depends on 1, 2)

A circuit as in claim 1 or 2, said second group including two subgroups of elements, establishing a three-phase, full-wave rectifier whose d.c. terminals are interconnected by an inductance.

### Claim 6 (depends on 1, 2)

A circuit as in claim 1 or 2, wherein said load includes a transformer having primary windings with taps, said first group being connected to the taps.

### Claim 7 (depends on 1, 2)

A circuit as in claim 1 or 2, wherein said load includes a transformer having secondary windings with taps, said first group being connected to the taps.