Wireless Series-Parallel Capacitor Charger for DC Circuit Breaker Applications

This paper studies the inductive series-parallel (SP) topology as a wireless capacitor charger for DC circuit breakers (DCCBs) including active injection circuits (AICs). The design objectives are achieving fast response time and minimized steady-state power losses. As the capacitor charging time is significant to accelerate the reclosing process in AIC DCCBs, the impacts of the input dc link voltage, the quality factor of the coils, the input-to-output voltage ratio, and the load capacitance parameters on the transient response time of the wireless SP charger are investigated. Also, a new burst mode control strategy is proposed to reduce the steady-state power losses. The developed 12V–100V wireless charger operating at 1MHz switching frequency provides isolation voltage up to 80kV considering 2kV/mm breakdown voltage between coils. Based on the experimental results, the 10μF load capacitor is charged to 80V in 2.37ms and to 90V in 2.9ms.