Modulation Techniques for Transformer-less Inverters

Abstract

In grid connected applications which is having low power, a single-phase inverter can have a good performance. As can be inferred from the title, the PV inverter is a key element of grid connected PV power system whose main function is the conversion the DC power generated by PV panel into the grid synchronized AC power. These inverters use either a low frequency transformer or a high frequency transformer. In PV applications it has been studied that the transformer can be removed in order to reduce the losses, cost, size and weight of the system simultaneously increasing the system performance. In this paper different inverter modulation techniques are discussed which are used to analyse the system changes which occur due to the removal of transformer. This paper also presents some of the most important topologies like diode-clamped inverter (neutral-point clamped), capacitor clamped inverter (flying capacitor) and cascaded-multilevel inverter.