Investigation of Split LCCL Tuning Network for High Power WPT Systems

Inductive power transfer (IPT) requires careful consideration of the design of the power supply topologies, especially as wireless power transfer (WPT) systems are pushed up to higher powers of hundreds of kilowatts. Primary circuits employ a DC/AC structure where a switching network creates a square-wave voltage or current that passes through a resonant tuning network. The tuning network attenuates the harmonics and creates a sinusoidal voltage across the primary inductance. In WPT for electric vehicle (EV) charging, the filter design becomes critical to ensure that electromagnetic interference (EMI) does not affect nearby electronics. To date, several of the IPT systems employ LCCL tuning network due to some of the desirable characteristics of LCCL filter. However, this tuning network can lead to sharp voltage transients at the terminals of the primary coil, emitting high EMI and making the system fail EMC standards. The paper investigates a split LCCL tuning network and its design method for DWPT systems to mitigate high $\frac{{dV}}{{dt}}$ at the pad terminals. An analysis is presented for the split LCCL network followed by the simulation results. The simulation is validated using a 15kW prototype comprising the proposed tuning network. Empirical results show significant reduction of voltage transients at primary pads.