A Fast Primary-Side Current and Voltage Control for Direct Wireless Battery Chargers

In traditional wireless power transfer (WPT) systems, constant current (CC) and constant voltage (CV)-based battery charging control strategies are applied to dc–dc converters on the receiver sides. In this study, the receiver-side control paradigm is shifted to the transmitter side and lumped as a primary-side current and voltage control that can: 1) rapidly determine the mutual inductances between the coupled coils regardless of misalignment (within tens of milliseconds); 2) eliminate dc–dc converters on the receiver sides; 3) implement constant frequency operations; and 4) automatically select current or voltage control mode without battery management chips and radio frequency (RF) communication. The combination of these four features offers a simple solution to reduce the complexities and sizes of receiver circuits for next-generation wireless battery chargers (WBCs). Only additional calibration circuits with limited components are required on the load ends. Both simulation and experimental results have validated the effectiveness of the proposed primary-side control for WBCs operating in both CC and CV modes. Practical results also showcase the automatic smooth transition from the CC mode to the CV mode.