International Journal of Engineering and Technology

The necessity of efficient topologies for photovoltaic (PV) inverters is a concern presently. With the advent of transformerless inverters, the size, volume and cost of PV inverters can be decreased. Efficiency can be increased nearly by 2% by avoiding the galvanic connection. With no galvanic isolation comes the problem of dc injection which pauses serious problems to core saturation of distribution transformers and cable corrosion and has to be limited as per IEEE, IEC standards. This paper presents a proportional resonant controller and is used along with a modelled series capacitance to limit DC injection. This avoids the use of a real capacitor in the output of the inverter used conventionally to prevent dc injection and hence overcomes the drawbacks of series voltage drops and reverse polarity effects. The topology of inverter chosen is the H-Bridge and switching scheme used is unipolar PWM considering the advantages of the same . A comparison of the dc injection values with and without the controller is presented for unipolar pulse width modulated (PWM) inverters.