Uninterruptible polyphase AC power supply

• US 4,665,322 A
• Filed: 10/29/1985
• Issued: 05/12/1987
• Est. Priority Date: 11/05/1984
• Status: Expired due to Term

• Current Assignee: Nishimu Electronics Industries Co. Ltd. (Kyushu Electric Power Company Incorporated)
• Original Assignee: Nishimu Electronics Industries Co. Ltd. (Kyushu Electric Power Company Incorporated)
• Inventors: Eishima, Yoshinori, Kawata, Yasuhiro
• Primary Examiner(s): Shoop, Jr., William M.
• Assistant Examiner(s): Ro, Bentsu
• Application Number:
  US06/792,498
• Time in Patent Office: 560 Days
• Field of Search: 307/20, 307/23, 307/31, 307/46, 307/66, 307/43, 307/45, 307/64, 307/82, 307/83, 323/206, 323/207, 323/212, 323/214, 323/215, 363/2, 363/71, 363/137
• US Class Current: 307/66
• CPC Class Codes: H02J 9/062 for AC powered loads
• CPC Class Codes: H02M 1/084 using a control circuit common to several phases of a multi-phase system

Abstract

An uninterruptible polyphase AC power supply equalizes an electric power taken out from a polyphase AC power source, even if unbalanced load is connected to output. The uninterruptible AC power supply comprizes a polyphase balanced phase shifter generating one control signal in synchronous with one phase of the AC power source and other control signals each having a prescribed phase difference with respect to said former control signal, a phase comparator comparing phases of said respective control signals with those of output voltage of the uninterruptible AC power supply to output correction signals whch minimize the phase difference between them, a plurality of phase shifters for signal phase to which are respectively supplied said control signals as well as said correction signal in the corresponding phases to generate invertor control signals in the corresponding phases, and a means for supplying the invertor control signals being the outputs of said respective phase shifters for single phase to the invertors in the corresponding phases.

Claims

1. An uninterruptible polyphase AC power source comprises:

a polyphase load;

a plurality of inverters, one for each phase of said polyphase load;

a plurality of single phase three-winding transformers, each first winding of said three-winding transformers being connected to one phase of said polyphase AC power source, each second winding being connected to one of said plurality of intervers, and each third winding being connected to one phase of said polyphase load;

a polyphase balanced phase shifter for generating at least one control signal in synchronism with one phase of said polyphase AC power source, and generating other control signals, each of said other control signals having a predetermined phase difference with said at least one control signal;

a phase comparator for comparing and minimizing phase differences between the control signals and the respective output voltages of the third winding of said plurality of single phase three-winding transformers, and to output a plurality of phase correction signals;

a plurality of single-phase shifters, each of said single-phase phase shifters responsive to one of said control signals and a corresponding one of said phase correction signals to generate an inverter control signal, one for each phase of said polyphase load, and each phase of said inverter control signals being supplied to the respective one of said plurality of inverters to control said plurality of inverters.

2. An uninterruptible polyphase AC power supply as claimed in claim 1 wherein said first and second windings are each coupled to said third windings by magnetic shunts.

3. An uninterruptible, multiple phase, alternating current power supply for providing power from a multiple phase power source to electrical loads where there can be one of said electrical loads for each power supply output phase, said power supply comprising:

a plurality of inverters, one for each power supply output phase;

a plurality of multiple winding transformers, one for each power supply output phase, each such multiple winding transformer having multiple windings thereon including first, second and third windings, each said first windings of each of said multiple winding transformers being adapted for connection to an alternative phase of said multiple phase power source, each said second winding of each of said multiple winding transformers being connected to an alternative one of said plurality of inverters, and each said third winding of each of said multiple winding transformers being adapted for connection to a selected electrical load;

a multiple phase balanced phase shifter for generating control signals including a synchronous control signal which is in synchronism with any selected phase of said multiple phase power source to which said first windings are connected, and including related control signals where each of said related control signals have a predetermined phase difference with said synchronous control signal, said predetermined phase differences between said related control signals and said synchronous control signal being established by at least one saturable transformer;

a phase comparator for comparing phase differences between said control signals and waveforms occurring on said third windings of said multiple winding transformers, said phase comparator providing a plurality of phase correction signals indicative of such phase differences; and

a plurality of phase shifters, each of said phase shifters responsive to at least one of said control signals and at least one of said phase correction signals to generate an inverter operation signal with each of said inverter operation signals being provided to a corresponding one of said plurality of said inverters to control relative phases of waveforms provided by said plurality of inverters to that said second winding of said multiple winding transformer to which each is connected.

4. The apparatus of claim 3 wherein said inverter operation signal from each of said plurality of phase shifters is generated through use of at least one saturable transformer.

5. The apparatus of claim 4 wherein said first and second windings are each coupled to said third winding by magnetic shunts.

6. The apparatus of claim 3 wherein said first and second windings are each coupled to said third winding by magnetic shunts.

7. An uninterruptible, multiple phase, alternating current power supply for providing power from a multiple phase power source to electrical loads where there can be one of said electrical loads for each power supply output phase, said power supply comprising:

a plurality of inverters, one for each power supply output phase;

a plurality of multiple winding transformers, one for each power supply output phase, each such multiple winding transformer having multiple windings thereon including first, second and third windings, each said first winding of each of said multiple winding transformers being adapted for connection to an alternative phase of said multiple phase power source, each said second winding of each of said multiple winding transformers being connected to an alternative one of said plurality of inverters, and each said third winding of each of said multiple winding transformers being adapted for connection to an electrical load;

a multiple phase balanced phase shifter for generating control signals including a synchronous control signal which is in synchronism with any selected phase of said multiple phase power source to which said first windings are connected, and including related control signals where each of said related control signals have a predetermined phase difference with said synchronous control signal;

a phase comparator for comparing phase differences between said control signals and waveforms occurring on said third windings of said multiple winding transformers, said phase comparator providing a plurality of phase correction signals indicative of such phase differences; and

a plurality of phase shifters, each of said phase shifters responsive to at least one of said control signals and at least one of said phase correction signals to generate an inverter operation signal through use of at least one saturable transformer with each of said inverter operation signals being provided to a corresponding one of said plurality of said inverters to control relative phases of waveforms provided by said plurality of inverters to that said second winding of said multiple winding transformer to which each is connected.

8. The apparatus of claim 7 wherein said first and second windings are each coupled to said third winding by a magnetic shunt.