High-Frequency Load-Independent WPT System for Multiple-Receiver with LCC-S Compensators

This paper presents a design of a load-independent wireless power transfer (WPT) system with multiple receivers and unified coupling coils. Various applications in each receiver require individual output voltages. In the proposed WPT system, LCC filters are adopted in front of transmission coils to improve the degree of freedom. The design theory of the LCC filter for achieving load-independent operation and the required individual output voltage is given. Consequently, the receiver can obtain the specified output voltages in each transmission coil; however, the variations of the coupling coefficient affect the output voltage. Since the load-independent operation can be maintained by satisfying specific conditions of the LCC filter, the proposed system always achieves zero-voltage switching and constant output, regardless of receiver load resistances in high power-delivery efficiency. From the experimental results, the effectiveness of the proposed WPT system and the validity of the design strategy can be confirmed. The experimental prototype of the two-receiver WPT system achieved 86.1% power-delivery efficiency at 6.78 MHz operating frequency and 19.6 V and 29.7 V output DC voltages.