Tapped-Inductor-Based Single-Magnetic Bidirectional PWM Converter Integrating Cell Voltage Equalizer for Series-Connected Supercapacitors

Abstract

Conventional supercapacitor (SC)-based energy storage systems require two separate converters, namely a bidirectional converter and a cell voltage equalizer. Each converter requires magnetic components, hence increasing the complexity, volume, and cost. This article proposes the single-magnetic bidirectional converter integrating a cell voltage equalizer. The proposed integrated converter is derived from the combination of a bidirectional pulsewidth modulation converter with a tapped inductor (TI) and a resonant voltage multiplier (RVM). The RVM is driven by the TI generating a square wave voltage with an arbitrary amplitude. Not only is the system simplified by the integration, but also the single-magnetic topology achieves circuit miniaturization. A 100-W prototype for nine SCs connected in series was built for the experimental charge–discharge cycling test. The voltage mismatch of SCs automatically disappeared during charge–discharge cycling, demonstrating the integrated functions of the proposed converter.