Efficiency Improvement of a H5 Transformerless Inverter with MOSFET-IGBT Hybrid Switches

The PV systems present power losses due to the switching and conduction of the power semiconductors. Moreover, passive elements also produce power losses that reduce the efficiency. In general, the power losses vary along with the variations of the irradiance, thus, at low power, the efficiency is low while at rated power the efficiency is maximum. In order to increase the efficiency during low irradiance intervals, this paper proposes a method to improve the efficiency in a photovoltaic inverter by means of the implementation of a hybrid MOSFET-IGBT switch which has been implemented for the H5 topology. The proposed solution consists in the use of a MOSFET and an IGBT connected in parallel. The main idea is to take advantage of the lower losses of a MOSFET in low power and the lower losses of an IGBT in high power. The proposed idea is validated by means of simulations, demonstrating the feasibility of the hybrid switches. The results show an improvement in the European efficiency and the California Energy Commission (CEC) efficiency, in this case is the European efficiency where the improvement is higher, however the behavior of the results indicate the hybrid switch can achieve a higher efficiency with a higher power if it is compare with the using of only MOSFET or only IGBT.