Balancing of Common DC-Bus Parallel Connected Modular Inductive Power Transfer Systems

The aim of this paper is to design a modular, fault tolerant multi transmitter(Tx) -multi receiver(Rx) parallel connected common DC bus inductive power transfer(IPT) system to replace slip rings in wind turbines or brushless exciters. In parallel connected common DC bus systems, current unbalance is a major issue which results in thermal stresses and over current or voltages. In this paper, two different new current balancing methods are proposed: Cross-coupled Rx modules and intentional miss-tuning of Rx side resonant frequency. These methods are investigated both analytically and experimentally for a single Tx and two Rx system for a 500 W prototype. The proposed methods are tested independently, and then the combined current balancing method is also investigated. For the same missalignment case cross-coupled/de-tuned has a 55.8% current balancing improvement compared to de-coupled/fullytuned topology.