Tapped-Inductor-Based Single-Magnetic Bidirectional PWM Converter Integrating Cell Voltage Equalizer for Series-Connected Supercapacitors
Masatoshi Uno, Kazuki Yashiro
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.