Primary-Side Resonant Current-/Voltage-Clamped IPT Systems Without Clamping Coil or Isolation Transformer for Inherent CC-to-CV Charging

A constant current (CC) and constant voltage (CV) inductive power transfer (IPT) charging system has become popular for battery charging applications. To achieve inherent CC-to-CV charging, the primary-side resonant current-/ voltage-clamped IPT systems are proposed in this article. Two configurations of the primary-side resonant current-/voltage-clamped IPT systems are introduced and analyzed based on the two-port network. In the proposed IPT systems, the clamping coil and isolation transformer are not required, which reduce the system cost and design difficulty of the loosely coupled transformer (LCT). By combining IPT topologies with input zero phase angle (ZPA) and load-independent CC or CV output, a family of IPT systems with inherent CC-to-CV charging can be obtained, which significantly simplifies the control complexity. The secondary-side compensation network is a first-order compensation circuit, which reduces the volume and weight of the charging device. Two primary-side resonant current-/voltage-clamped IPT systems are selected to analyze the sensitivity of the parameters to the input impedance, as well as CC and CV outputs. Soft switching and minimized reactive power can be achieved, which reduce the power rating of the power supply and minimizes the switching loss. Finally, experimental prototypes are built to verify the proposed IPT systems.