CONTROLLER AND METHOD FOR VARIABLE SPEED GENERATOR-MOTOR

PROBLEM TO BE SOLVED: To prevent excessive rise in power frequency, even when the power is lost during three-phase short circuit or when a generator-motor is cut off an AC power source. SOLUTION: This controller detects a slip phase, based on the phase of the rotor of a generator-motor and the phase of the power voltage detected with a power voltage phase detector 7 and excites the generator-motor 5, based on the slip phase. In this case, the power voltage phase detector 7 creates a power voltage phase value using the frequency approximately equal to the frequency of the power voltage made within, in place of the power phase detected value when it detects the amplitude of the power voltage falling below specified. Hereby, even in power loss during three-phase short circuit of the power source, an output voltage of the generator-motor of specified frequency can be output.