A power system for a reactive gas generator can include a direct three phase inverter. A resonant tank can further be included to receive a square wave output of the direct three phase inverter and provide a sine wave output. The power system can include an inverter controller that turns on and off selected switches of the direct three phase inverter based on states of the three phases of a three phase AC power supply, where a switch is turned on with an adaptive ON time and a modulated OFF time depending on a desired output power.