Output-Power-Controllable Parity-Time-Symmetric Wireless Power Transfer System With Soft Switching for Kitchen Appliances

In this paper, using dual-frequency modulation (DFM) and phase synchronization method (PSM), a flexible and controllable wireless power transfer (WPT) system with soft switching based on parity-time (PT) symmetry is proposed for kitchen appliances. Here, the system outputs can be regulated by configuring the number ratio of two modulation pulses with different frequencies, without the need for extra DC-DC converters or changing the duty cycle of the inverter. Moreover, a control method for generating and arranging the hybrid frequencies pulse sequence is proposed based on PSM to satisfy the condition of PT symmetry. Theoretical analysis indicates that a controllable output power insensitive to the coupling coefficient can be acquired only by relying on a single-stage inverter while maintaining soft-switching or zero-voltage switching (ZVS) operation, thereby reducing power losses and improving system cost-effectiveness and integration. Furthermore, dual-side communication can be eliminated. The results of the experiment confirm that a controllable stable output power with a constant coil-coil efficiency of 95.8% and a peak DC-to-load efficiency of 93.8% can be maintained within a lateral tolerance range of 0-14 cm.