A carrier-based medium vector PWM strategy for three-level inverters in transformerless photovoltaic systems

This paper proposes a new carrier-based PWM strategy for three-level inverter in transformerless photovoltaic systems. The proposed modulation method completely eliminates leakage currents by employing only medium vectors and one zero vector which produce the same common mode voltage. Due to carrier-based scheme, the proposed PWM method can allow overmodulation and be intuitively understood and simply implemented with analog or digital hardware. To show the feasibility of the proposed PWM method, the simulation results are presented.