A Self-oscillating Controller Based on Pulse Density Modulator in Wireless Power Transfer

This paper proposed a self-oscillating controller based on pulse-density modulator (PDM) in wireless power transfer (WPT). Without utilizing additional dc/dc converter, the output voltage could be regulated by both the transmitting side inverter and receiving side rectifier. Therefore, both the system topology and controller complexity are reduced. Moreover, by detecting the zero-cross of the alternating current, the soft switching state on each switch is achieved and the switching frequency is synchronized to the system natural frequency. Thereby, the system has its maximum performance. For validation, a 350W WPT system was established. The experiment results indicate that the overall efficiency ranges from 83.5% to 93.6% of which the efficiency in buck mode are above 91.3% and in boost mode ranges from 83.5% to 92.2% respectively.