Title:
STAGED MOTOR STARTING AND WYE/DELTA SWITCHING
Document Type and Number:
WIPO Patent Application WO2006035194
Kind Code:
A3
Abstract:
A method of starting and apparatus for starting a multiphase electrical machine is disclosed. The aim is to reduce oscillatory pulsation in torque generated by the motor and inrush current that occurs shortly after start-up. The starting method comprises the steps of first connecting at least one, but less than all, of a plurality of windings to a respective phase-shifted supply voltage at a controlled point in the supply phase. Then, after a controlled delay following the connection made in step i., connecting the or each remaining winding of the machine a respective phase-shifted supply voltage. The invention has particular application to multiphase (most usually, 3-phase) motors. However, it can also be applied to other electrical machines, such as generators and transformers. The method can be performed at initial start-up or, in the case of application to a motor, at Y-delta switchover. On reconnection of a load generating a significant back emf, the 2-step process is initiated when the back emf is substantially in phase with the phase of the supply voltage.
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Inventors:
UNSWORTH PETER J (GB)
KINSELLA JAMES JOSEPH (US)
KINSELLA JAMES JOSEPH (US)
Application Number:
PCT/GB2005/003503
Publication Date:
July 20, 2006
Filing Date:
September 12, 2005
Export Citation:
Assignee:
UNSWORTH PETER J (GB)
KINSELLA JAMES JOSEPH (US)
KINSELLA JAMES JOSEPH (US)
International Classes:
H02P1/26; H02P1/24; H02P1/32; H02P3/20
Foreign References:
US5481171A | 1996-01-02 | |||
GB429200A | 1935-05-27 | |||
US5859513A | 1999-01-12 | |||
US3646415A | 1972-02-29 | |||
US3767987A | 1973-10-23 | |||
US1796220A | 1931-03-10 | |||
JPS62207195A | 1987-09-11 |
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