A MOSFET Transformerless Inverter with Reactive Power Capability for Micro-inverter Applications

The state-of-the-art transformerless inverters can use MOSFET to achieve high efficiency, but difficult to do reactive power generation for upcoming standards. This paper proposed a MOSFET based transformerless inverter and a novel PWM modulation method for reactive power generation. PWM modulation and circuit operation are then detailed under reactive power generation condition. Ground loop voltage is derived with common mode and differential model circuit analysis. The hardware prototype of a two-stage micro-inverter with the proposed MOSFET inverter as the secondary stage has been designed. The experiment results demonstrate the reactive power capability, high efficiency, and high-frequency component free of the ground loop voltage of the proposed transformerless inverter.