A control apparatus and method are provided for a load energized by an inverter coupled with a DC power source. The lag current angle between the current and the load voltage is utilized to determine when the output current is positive and when the output current is negative. The conduction times of the respective upper and lower gate turn off thyristors of each pole of the inverter are controlled in relation to the established current angle, with a provided modification of those conduction times being phased out in response to the desired output voltage for said load.