Transformer-Less Novel Hybrid Converter Based Solar PV fed UPS System

Abstract

The uninterrupted power supply (UPS) plays a dominant role in domestic appliances and also the growth rate of solar roof top system implementation is massively increasing day by day. To minimize the cost on the converters, solar PV power is directly connected with existing UPS with separate MPPT controller. However, due to the presence of nominal frequency transformer, the size and cost of UPS becomes more. In addition, it consumes the power with poor power quality to charge the battery. Apart this, the current supplied from the battery is much higher due to the lower voltage level of battery, which makes voltage dip during peak load condition and resulting to shorten the battery life and degrades its performances. In order to overcome all these drawbacks, this particular paper proposes a transformer-less novel hybrid converter based solar PV fed UPS system. In the hybrid structure, the gain can be achieved higher with minimum components counts. The novelty of the proposed transformer-less hybrid converter is that the regeneration of switched capacitor voltage is applied to input of switched inductor network in DC–DC converter, due to this hybrid structure the gain has been extended drastically with minimum number of devices. Also the coordinated control algorithm is implemented in solar PV fed UPS to take the decision according to the situation of generation, load and battery back-up. The detailed operation of the proposed coordinated control algorithm has been addressed in this paper. Moreover, the detailed simulation study is carried out for each mode of operation and measured results are obtained and presented in this paper.