| 摘要 |
PROBLEM TO BE SOLVED: To swiftly resume operation of a PWM cycloconverter, when power failure occurs, especially when instantaneous service interruption occurs and power is restored. SOLUTION: The PWM cycloconverter comprises a power failure detector which detects any failure in input power supply; a utility power phase detector which detects the phase of input voltage; an instantaneous power phase detector, which calculates power supply phase from the magnitude relation of the instantaneous values of input voltage; and a power supply phase selector, which selects as input phase either the output of the utility power phase detector or the output of the instantaneous power phase detector. When the power failure detector does not detect failure, the power supply phase selector selects as input power supply phase a power supply phase obtained at the utility power phase detector. When the power failure detector detects a failure, the power supply phase selector selects as input power supply phase a power supply phase obtained at the instantaneous power phase detector. COPYRIGHT: (C)2004,JPO
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