AC-EXCITED MOTOR GENERATOR AND ITS OPERATION METHOD

PROBLEM TO BE SOLVED: To provide an AC-excited motor generator that can extend a stable operation range even in a range of shortage excitation, and its operation method. SOLUTION: In the operation method of an AC-excited motor generator where a current controller 18 of an AC-excited generator 3 controls a current by dividing into a q-axis current component for controlling an effective power and a d-axis current component for controlling a reactive power, a primary voltage phase operator 21 that calculates a voltage phase θv of a primary voltage based on the output of the above power detector, a rotor phase detector 12 that detects a rotary angle θr being indicated by the electrical angle of the AC-excitated generator 3, a phase detector 20 that calculates a difference between the voltage phase θv and the rotary angle θr (θs =θv -θr ) are provided, thus controlling the current controller 18 so that the speed of the secondary current of the AC-excited generator 3 becomes faster than the change in the angular velocity of the rotor.