Aiming at the problem of interpolar voltage unbalance in bipolar low voltage dc (BLVDC) microgrid, a family of bipolar dc–dc converters with interpolar voltage self-balancing is proposed in this article. The proposed converters are composed of a full bridge inverter and four types of bipolar voltage multiplier (BVM) circuits. Benefiting from the characteristics of the proposed topology, its output power can automatically flow to the output side with lower voltage and has the ability to maintain the voltage balance between BLVDC buses. In addition, the proposed converters have ZVZCS soft-switching characteristics, and the control and driving circuits are consistent with the traditional full bridge inverter. The topology derivation, working principle, soft-switching and voltage self-balancing performances of the proposed converter are analyzed, and a 1 kW experimental prototype with its control system is designed. The experimental results verify the accuracy of the theory and analysis.

The bipolar dc power architecture provides a new high-efficiency and high-reliability solution. Maintaining interpolar voltage balance is crucial in bipolar structures to ensure the reliable and stable operation of the system. This article proposes a family of bipolar dc-dc converters based on bipolar voltage multipliers (BVMs). Notably, the proposed BVM structure has the capacity to autonomously achieve interpolar voltage balance without external balance control strategy. This inherent feature significantly alleviates control circuit complexity. Meanwhile, the BVM structure possesses rectification functionality, facilitating its connection to various front-stage structures with ac output. This article provides a detailed exposition of the operational principles and performance analysis of the proposed voltage balancers (VBs) and discusses a 1-kW prototype experiment. The experimental results validate the accuracy of the theoretical analysis.

A flyback converter with a high transformer utilization ratio and high voltage conversion gain for photovoltaic application is proposed in this paper. By adding the “coat circuit” to the topology of the basic flyback converter, the energy can be transferred from the primary winding of the transformer (Tp) to the secondary winding of the transformer (Ts) when the switch is working not only in off-state but also in on-state, which effectively improves the utilization, reduces the maximum electromagnetic flux density of the transformer during charging, and avoids the saturation of the transformer. Additionally, the “coat circuit” can also increase the voltage conversion gain of the flyback converter and reduce the voltage stress of devices, making the proposed converter attractive for photovoltaic power systems. This paper analyzes in detail the working principles and performances of the proposed converter. The theoretical analysis is further corroborated through simulation and experimentation using a prototype with a power rating of 200W.