CIRCUIT DESIGNS AND ENGINEERING SOLUTIONS BASED ON SYNCHRONOUS RECTIFIER FOR WIRELESS ENERGY TRANSFER SYSTEM
K.D. Krestovnikov, Е.О. Cherskikh, А.R. Shabanova
This paper presents circuit designs and engineering solutions for wireless energy transfer system (WETS), aimed to increase transmitted power and battery charger performance efficiency. This problem was solved by integration of the previously developed synchronous rectifier into the receiving part of the system. The distinctive feature of the WETS is its control system, required for adjustment of performance parameters, protection from inadmissible operating conditions and for human-machine interactions, using diagnostic message output onscreen. To maintain the required resonance frequency in the receiving part of the device a resonance self-oscillator. Application of identical components in both circuits allowed to obviate the need in additional subsystems for frequency tuning to achieve the required resonance value in the receiving part. To simplify the WETS fabrication and assembly process, identical materials for cases of receiving and transmitting parts were chosen, as well dimensions for coil socket in each part. Comparative study of WETS performance efficiency of WETS, where the receiving part is equipped with a rectifier on Schottky diodes and a synchronous rectifier. It was revealed, that previously developed circuit design of a synchronous rectifier allows to improve WETS efficiency by 5,38 % under load current of 4,5 A. Additionally, the following dependencies were obtained: synchronous rectifier efficiency depending on load current, energy transfer efficiency depending on transferred power and characteristic curves for different distances between the receiving and the transmitting part. The power transfer efficiency when using the presented WETS prototype was 76,47 % by transmitted power of 125 Wt. Transmitted power increase at least by 30 % compared to similar wireless battery charging devices shows, that the charging period duration is decreased.
Keywords: wireless energy transfer, circuit design, battery charging device, synchronous rectifier, resonance self-oscillator, Schottky diode.