Small-signal Modeling for Adaptive Closed-loop Control in Two-coil Wireless Power System

In this paper, a small-signal modeling for an adaptive closed-loop control in two-coil wireless power transfer (WPT) system is presented and discussed. In the WPT system, the output voltage/power is controlled to maintain constant under changing transmission distances (DIS) and misalignment (MIS) conditions between transmitter coil (Tx) and receiver coil (Rx). The WPT system consists of a non-inverting buck-boost converter, a switching power amplifier (for DC to AC conversion), a Tx coil, a Rx coil, a full-bridge rectifier (for AC to DC conversion) and a micro controller unit. Modeling for the system is analyzed to facilitate and guide the design of the controller. The developed small-signal modeling is evaluated and validated by the system bode plots and voltage reference transient experimental results. Detailed sets of modeling derivation are analyzed and discussed throughout the paper and the system operation and performance are evaluated.