A Bidirectional Wireless Power Transfer System with Constant Power Output

Abstract

Bidirectional wireless power transfer (BWPT) is an emerging technology within the wireless power transfer field of research, which allows the same device to receive power and it can transmit power to other compatible devices. In practical applications, due to the distance of the coil, the lateral misalignment and the angular misalignment, it is difficult to achieve constant power transmission. This paper proposes an adaptive adjustment scheme, which detects the output power of the circuit in real-time through a closed-loop feedback method, uses ergodic sampling to obtain the best duty cycle, and adaptively adjusts the duty cycle of the inverter pulse width modulation signal, to compensate for the reduction in load power. Furthermore, the validity and feasibility of the scheme are verified by simulation and prototype experiments. A maximum constant power transmission of 4W is achieved within the range of 5 cm in longitudinal distance, 4 cm in lateral displacement and 60° of angular misalignment. The maximum BWPT efficiency can be achieved, up to 66.17%. The proposed method improves the quality of BWPT.