Capacitive Power Transfer System using a Cascaded Improved One-Pulse Switching Active Capacitor

Recently, contactless electric power distribution has become a very attractive method for providing electric power to mobile equipment such as mobile phones or electric vehicles. Inductive power transfer (IPT) with inductive coupling is currently the most popular way to realize contactless electric power distribution. Another way is capacitive power transfer (CPT) with capacitive coupling. In the past, several studies on CPT have effecively used series LC resonance to enhance the transfer power. However, LC resonance is sensitive to parameter changes, which may be caused by the contact conditions of the capacitive coupling. The authors propose a new power converter suitable for a CPT system that uses a novel improved one-pulse switching active capacitor (I-OPSAC) to enhance power transfer. The proposed system improves the power transfer efficiency without LC resonance and is robust to parameter change. One of the major advantages of I-OPSAC is stable operation without any feedback loops including DC capacitor voltage control. The other major advantage is the easy-to-realize series connection. The paper reports the control scheme and detailed operational characteristics of a cascaded I-OPSAC (C-I-OPSAC), in addition to the simulation and experimental results. The results verified that a C-I-OPSAC enhances transfer power while maintaining stable operation without a feedback loop.