A Family of Symmetrical Bipolar Output Converters Based on Voltage-Multiplying Rectifiers for Interfacing Renewable Energy With Bipolar DC Microgrid

The bipolar dc microgrid system is considered a greatly promising solution to interface various renewable energy sources and emerging loads due to its advantages in efficiency and reliability. However, pole voltage imbalance and lack of superior bipolar power conversion topologies limit the development and application of bipolar dc microgrid systems. In this context, this article proposes a family of multiport converters based on voltage-multiplying rectifiers to achieve symmetrical bipolar output voltage and power conversion between renewable energy sources and bipolar buses. In the proposed topologies, single-stage power conversion, without voltage balance feedback control, and a low number of components are obtained. Furthermore, the bulky balancing inductor is eliminated to improve conversion efficiency and reduce the volume of the system. Moreover, the higher voltage gain, smaller input current ripple, and lower voltage stress of semiconductor devices make it ideal for interfacing renewable energy sources with bipolar dc microgrids. The derivation method for the proposed topology family is first introduced. Then, a typical topology in the proposed converter family is analyzed in detail as an example, including the operation principle, steady-state performance, parasitic parameter effects, design considerations, efficiency analysis, control method, loop designing, etc. Finally, a 1-kW prototype is developed and tested to verify the performance of the proposed converter.