A Modulation Strategy for a Single-Phase Transformerless Multilevel Inverter with Dual Bidirectional Switch

Nowadays, there is an increasing interest to use renewable electrical energy sources instead of those based on fossil fuels. Must of the commonly used are the solar and the wind energy which have become very popular in last years. Solar energy uses solar panel arrays to generate electrical energy with a direct current (DC) waveform. Therefore, in order to inject the generated energy to the electrical grid, it is necessary to convert the DC signal into an alternating current (AC) signal. Multilevel inverters allows the grid connection with a good power quality and reducing the output filter size. In particular, direct grid connected inverters, additionally provides low size and low cost to the final system. In this paper, a pulse width modulation (PWM) strategy is designed for a hybrid multilevel inverter based on a T-type inverter combined with an AC-decoupling technique. The PWM method is intended to reduce leakage ground current which is one of the must important issues in transformerless inverters. Simulation results are provided in order to validate the proposed strategy.