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

The aim of this article 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 that results in thermal stresses and over current or voltages. In this article, two different new current balancing methods are proposed: cross-coupled Rx modules and intentional detuning 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 misalignment case, cross coupled/detuned has a 55.8% current balancing improvement compared with decoupled/fully tuned topology.