Improved Dual Boost Inverter With Half Cycle Modulation

The output voltage of a traditional full-bridge inverter is lower than the input dc voltage. In applications when the input voltage is low, the front-end step-up converter is usually required, presenting a two-stage power conversion. Dual boost inverter (DBI) can realize single-stage conversion, which has the advantages of a simple structure, less power devices, and buck-boost ability. The traditional modulation strategy of DBI makes all power switches operate in high frequency and sustain high voltage/current stress, which leads to heavy conduction and switching loss. This paper proposed a modulation strategy, namely, half cycle modulation (HCM), which makes power switches work in high frequency just in half cycle, and can greatly reduce the conduction and switching loss of the power devices. Furthermore, to reduce the current circulation loss in DBI, an improved DBI with two clamping switches is proposed based on HCM, which can bypass the inductor current with low stress switches; therefore, the loss caused by circulation current can be greatly reduced. A detailed analysis and comparison between the traditional and HCM strategies are given in this paper. Finally, a 500 VA DBI prototype is designed in the lab. The advantages of the proposed HCM strategy and improved DBI with two clamping switches are verified by experimental results.