Performance enhancement of wireless battery charger by a two-phase parallel inductive power transfer topology

Abstract

In this study, a wireless battery charger based on a two-phase parallel inductive power transfer (IPT) topology is developed. The charging power is shared by the two-phase parallel IPT circuits to improve efficiency. The power transferring distance can also be increased by adding the coils of the second phase. A hybrid resonant compensation of LCC-LCC/LCC-S is adopted to provide stable current or voltage output for charging the battery pack. The wireless closed-loop controller is implemented via RF communication. The coils of two-phase IPT circuits share the same magnetic field space to avoid increasing system volume. Decoupling capacitors are added to the RXs to eliminate the cross-coupling effect. The proposed two-phase parallel IPT-based wireless battery charger and a single-phase IPT-based charger are both constructed. The rated output voltage and current are 86.4V and 6A for charging a common 72V/36Ah battery pack. Compared with the single-phase topology, the topology of a two-phase parallel can extend the air gap distance for providing the same output power. The efficiency is also increased by about 3% in CC mode and 2% in CV mode.