부산대학교 도서관

The human intervention free bidirectional efficient energy exchange between the grid and Electric Vehicles (EVs) relies on effective bidirectional power flow control in Wireless Power Transfer (WPT) system. This essential bidirectional control feature enables the grid to charge the EV’s battery and, during surplus energy periods, allows the EV to feed power back to the grid. This capability facilitates the implementation of Vehicle-to-Grid (V2G) functionalities. Implementing this bidirectional flow requires sophisticated modulation techniques to ensure seamless power transfer and optimize overall efficiency. In comparison to pulse width modulation, pulse density modulation (PDM) proves more effective in minimizing switching losses in the converter. PDM efficiently manages the amplitude of high-frequency pulses generated by the inverter and converter systems for WPT applications. However, the PDM techniques are not effectively investigated in the bidirectional wireless power transfer system (BWPT). In this paper, Fuzzy Logic Controlled Pulse Density Modulation (FLC-PDM) approach for the BWPT is proposed for the first time. This approach uses dual side pulse density control for high-frequency converters with the fuzzy rule base to adjust the pulse density and duty ratio based on the load demand. The proposed approach aiming to optimize efficiency across diverse loads and regulate the output voltage and provides effective control approach for the BWPT system. This method ensures constant switching frequency output voltage regulation and delicate shifting operation for high-frequency converter switches, requiring no additional components. The circuit simulations and hardware prototype testing are performed for the 3.7 kW power rating and 85 kHz operating frequency to validate the proposed FLC-PDM approach for the BWPT circuit and yielded an efficiency over 93% across diverse load resistances and pulse densities.