AC POWER SOURCE FOR VEHICLE

PURPOSE:To prevent fuel from being used up by suppressing the rise of an idle speed when the fuel becomes a predetermined quantity or less. CONSTITUTION:A controller 102 controls the conduction ratios of power transistors 100a-100d to regulate an effective value to be applied to an AC load 101 to a constant value. When an engine speed does not arrive at an upper limit value and the output voltage V0 of a full-wave rectifier 10 is less than 100V, it instructs to increase the idling speed. On the other hand, if the fuel is less than a predetermined value, the instruction of acceleration of the idling is canceled. Thus, it can avoid the state that a vehicle cannot be moved due to the lack of fuel.