Highly-reliable double-switch cell equalizer using parallel-resonant inverter and voltage multiplier for series-connected supercapacitors/lithium-ion cells

A novel cell equalizer using a parallel-resonant inverter (PRI) and voltage multiplier (VM) is proposed. The required number of switches and magnetic components can be dramatically reduced compared to conventional equalizers, thus achieving simplified circuitry and compactness. In addition, the proposed equalizer can work safely, even in the event of short-and open-failure of cells, meaning high reliability. A dc equivalent circuit of the proposed equalizer was mathematically derived and experimental equalization tests were performed for six supercapacitors (SCs) connected in series to demonstrated the equalization performance.