AC/DC powered microwave oven

摘要

A microwave oven is described suitable for use on transports where DC power is available. The microwave oven employs a first inverter to generate internal AC power that is then used to operate the microwave components other than the magnetron microwave source. The internal AC power is passed with relatively low current through the oven interlocks to activate and drive a power inverter that, through an additional output transformer winding, delivers high voltage power to the magnetron. In a preferred embodiment a relay, that is connected to sense when external AC power is available, causes an automatic switching that decouples the internal AC power from the power inverter to enable conventional operation from external AC line power. When external AC line power is no longer applied, the microwave oven automatically switches to operate from the available DC power. An efficient cooling fan is provided that is driven by a DC motor. The motor is provided DC power that is derived from a reverse coupling of AC line power through a transformer used at the output of the first inverter. During a DC power mode, the DC power available at a center tap of the primary winding of this transformer is used to drive the DC motor. Operating controls are described for the power inverter.