Voltage control apparatus of engine generator and control method thereof

The invention provides a voltage control apparatus of an engine generator having a simple structure and capable of being made compact, and a control method thereof. Accordingly, in a method of controlling a voltage of an engine generator, the method includes steps of detecting an actually measured value (Ne) of an engine rotational speed at every predetermined time and controlling an output voltage of the power generator (4) in accordance with a deviation value (alpha1) between a predetermined target value (Ne1) and the actually measured value when the actually measured value is equal to or less than the target value. Further, the method includes the steps of detecting an actually measured value (Q) of a fuel injection amount of an engine (1) and an actually measured value (Ne) of a rotational speed at every predetermined time and controlling an output voltage of the power generator in accordance with a deviation value (alpha2) between a predetermined target value (Q1) of the fuel injection amount with respect to the actually measured value of the rotational speed and the actually measured value of the fuel injection amount. Further, the method can be made such as to detect the actually measured value of the engine rotational speed at every predetermined time and control the output voltage of the power generator on the basis of the time change rate of the actually measured value.