Single-phase bidirectional bridge topology without electrolytic capacitor at the DC side

Abstract

The DC current of the single-phase inverter or rectifier contains low frequency ripple whose frequency is twice that of the AC voltage. Traditionally, electrolytic capacitor is used to eliminate these ripple, but it has relatively short lifespan and affect the lifetime of the entire inverter or rectifier system. In this paper, a single-phase bidirectional bridge topology without electrolytic capacitor is presented. The bidirectional topology combines a conventional converter and a pair of additional switches. In addition, the bidirectional bridge topology can control the pulsation power at the ac side due to the two differential capacitors, which is produced by splitting the AC filter capacitor of the conventional inverter or rectifier symmetrically. The DC current ripple of the bridge converter can be significantly reduced without the electrolytic capacitors (E-Cap). Theoretical analysis and results are provided to explain the operation and showcase the performance of the bidirectional bridge topology. All the experimental results are provided to support the feasibility of the proposed work.