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The bipolar DC bus configuration has been widely used in DC nano-grids due to its flexibility and stability. Input-parallel-output-series (IPOS) converters are utilized in bipolar DC bus and RES applications due to their simple structure. However, there is a big challenge with this structure. To ensure system safety and stability, the two output voltages of an IPOS converter need to be balanced. On this basis, an IPOS three-state boost converter with a balanced output voltage is proposed in this paper. At the same time, output voltage balance can be obtained by adjusting the duration of the three-state converter based on the volt-second balance method. In the proposed strategy, a switch series diode is added to the IPOS Boost converter topology, and the voltage across the main inductor can be changed through one degree of freedom, where the corresponding output voltage is regulated due to a change in inductor voltage. In addition, under different dead time conditions, adjusting the gate drive of the switch can be used to achieve voltage balance. Moreover, a comprehensive analysis and relative calculations are provided. Finally, a 20–200 V prototype is built to verify the analysis. [ABSTRACT FROM AUTHOR]

High voltage step-down converters are very popular in distributed power systems, voltage regular modules, automatic vehicles, etc. To avoid extreme duty cycles, a series capacitor-based buck converter with a coupled inductor is proposed in this paper. In this converter, the voltage stresses of the power switches are clamped to half of the input voltage. Thus, low voltage rating MOSFETs with a low Rds,on could be utilized to improve the performance of the proposed converter. Moreover, synchronous MOSFETs are also used to reduce the conduction losses of the switches. Zero voltage switching (ZVS) for the main power switches is achieved using the coupled-inductor technique. In addition, through adding a bypass flowing path, a negative current is established to guarantee the ZVS condition of the power switches. The operating principle of the proposed converter is described in this paper, and the DC voltage gain ratio, automatic current sharing, soft switching condition and design guideline of the critical parameters are also given. Finally, experimental results obtained from a 60 V/200 W prototype are presented to verify the analysis of the proposed converter. [ABSTRACT FROM AUTHOR]