ENGINE GENERATOR

PURPOSE:To eliminate a starter and to simplify the structure of control system by a method wherein a rotor position detecting means and the main circuit of a power converter function corresponding to the brush and the commutator of a DC motor, when an engine is started, and a synchronous generator functions as a motor to start the engine. CONSTITUTION:A main circuit 13 converts the power from a DC power source 15 into three-phase AC voltages U, V, W having frequency synchronous with the rotary speed N of a generator 3, then the converted power is fed to a generator 3 which functions as a motor and starts an engine 1. In other words, a rotor position detector 10 and the main circuit 13 of an inverter correspond to the brush and the commutator of a DC motor while the generator 3 performs motor function and functions as a starter for the engine 1. One phase switching element SW of the power converter main circuit 13 performs low frequency SW operation continuously while other two phase SW elements perform SW operation alternately every half cycle thus operating the main circuit 13 with optimum conversion efficiency during both single phase motor operation and three-phase motor operation.