A Compact and Coupling-Smooth Magnetic Coupler Design for AGV Wireless Charging Application

A compact magnetic coupler of inductive power transfer (IPT) system for automated guided vehicles (AGVs) is proposed in this paper, which consists of a double-D (DD) transmitter (Tx) and a compact dual-coil receiver (Rx). By overlapping between one coupling peak point and another coupling null point of two Rx coils, the Rx of the magnetic coupler achieves relatively small output voltage fluctuations, as well as minimizes its size. In addition, to eliminate cross-coupling of the dual-coil Rx, a mutual decoupling device composed of two lumped inductors is adopted, which possesses the same mutual inductance as the dual-coil Rx. Finally, based on the proposed magnetic coupler and its unique way of decoupling, a 3kW IPT system is constructed with 180mm
$\times 390$
mm Tx, 150mm
$\times 210$
mm Rx, 40mm air gap magnetic coupler, and inductor/capacitor/capacitor-series (LCC-S) based decoupling compensation network. The experimental results show that output voltage varies in proportion to the mutual inductance of Tx and Rx. The measured efficiency is 89.5% to 94.5% under the voltage range of 155V to 220V during the 90mm misalignment.