Patent ID: 8773081

Claim:
A controller for controlling a power generator including: a rotor with a field winding; and at least one-phase stator winding, the rotor being rotatable by rotational power supplied from an engine, the controller comprising: a switch connected with the field winding; a voltage controller configured to operate, in an initial excitation mode, to turn selectively on and off the switch to supply an excitation current as an initial excitation current to the field winding, and operate, in a power generation mode, to selectively increase and reduce the excitation current to be supplied to the field winding to regulate an output voltage of the power generator to a target value; a rotation-number measuring unit configured to measure a rotation number of the rotor based on a phase voltage induced in the at least one-phase winding; and a mode-shift determiner configured to, while the voltage controller operates in the initial excitation mode, determine whether to shift an operation mode of the voltage controller from the initial excitation mode to the power generation mode based on: the measured rotation number of the rotor, a threshold rotation number of the rotor, and a preset time period, the time period being equal to or longer than an expected maximum value of cycle of pulsations of rotation of the engine.