A Current Balance Control Strategy Applied in Inductively Coupled Power Transfer System With Multiple Parallel Pickup Modules

For large power application of inductively coupled power transfer (ICPT) system, such as traffic railway, multiple pickups have to be adopted. The condition exists that current unbalance of ICPT system with multiple parallel pickup modules, which will cause instability and low reliability. Aimed to solve the issue, the paper analyses the uncoupled module of ICPT system, assesses the impact of the mutual inductance, compensated state, and coil resistance on current unbalance, and put forward a novel current-balance strategy to balance the parallel currents by introducing the circuit of impedance transformation including semi-controlled rectifier, and BUCK, and BOOST circuits. Experiments have been done on the platform of ICPT prototype, and the experimental results are presented to show the correctness of the theoretical analysis and the effectiveness of the control strategy. When the output voltage is 220 V and load is 6 Ω, the output power is 8 kW. The amplitude ratio of the two parallel currents is 2.04 without control, and the amplitude of the two current is almost equal when adopting the strategy. System efficiency stays constant or increases slightly after adopting the proposed control strategy.