Receiver-Position-Based Unbalanced-Current Control for a Three- to Single-Phase Wireless Power Transfer System for AGVs

Abstract

Conventionally, three-phase wireless power transfer systems apply balanced currents with open loop control. The balanced current enables the receiver coil to receive uniform power regardless of its position. The phase-coil away from the receiver coil, however, dissipates the same power as that close to the receiver coil while the far phase-coil contributes to little power transfer. This paper presents a receiver-position-based unbalanced-current control. In the unbalanced-current control, a close phase-coil has higher current amplitude than far phase-coils. Therefore, the proposed control can improve the transfer efficiency in comparison with the system with the balanced-current control. The proposed control can dynamically estimate a moving receiver position with the voltage and current in the three-phase inverter and can generate required currents owing to its feedback control. The experiments using the system with a prototype of three- to single-phase wireless power transfer coil and a fabricated inverter implementing the proposed control prove that the system can dynamically transfer uniform power to a moving automatic guided vehicle (AGV) and can perform with 5% improvement in transfer efficiency in comparison with a system implementing the balanced-current control.