Coupling and Load Estimation with Current and Voltage Primary Sensing in Free Communication Wireless Power Charging

In recent years the implementation of wireless power systems has increased due to improvements in technology and efficiency. Some advantages of wireless power transfer technology are reliability, safety, and convenience of use. One of the challenges with these systems is output regulation, as there are no physical wires to access it. Further complications are the variability of coil coupling and output power in the case of chargers. Firstly, this paper has summarized some of the main techniques for controlling the output of inductive power technology. Moreover, a predictive free communication control from the primary is proposed. It is aimed at charging systems with constant but unknown coupling, using a small drone charger as a reference. This control allows the secondary side to be simplified and acts faster than a control loop at the output due to the predictive measurement and feedforward operation. The simulation results for an output voltage of 5 V show an error of less than 3 % for a coupling range of 0.25 to 0.5.