Abstract: It is difficult to control a variable speed converter or inverter so that an AC motor or other load may be operated from a DC source under varying source and/or load conditions. A DC bias voltage control related to AC frequency by a predetermined relationship is used to control the DC to AC converter. For variable speed AC converters, a low voltage bias control circuit is effectively used to control motor frequency by applying a bias voltage to the converter so that the load requirements are optimally met by the available DC source voltage. The controller can be used in many DC source—bias controlled converter—AC load systems formed with the bias controlled drive, for example a solar powered water pump in which a DC photovoltaic panel is used to power an AC pump motor.