Optimal Coil Design and irDA-Based Communication Method for Auto-Guided Vehicles with Thermally Stable and High-Efficiency Operation

In this paper, an optimal coil design methodology for inductive power transfer (IPT) systems is proposed, providing a systematic and practical approach for coil designers working with voltage-source-based series-series topologies. Unlike conventional designs, the proposed methodology explicitly considers frequency splitting phenomena, ensuring both thermally stable and high-efficiency operation while simultaneously identifying the optimal frequency range for effective load power regulation. Using finite element method (FEM) analysis and circuit simulations, the transmitter (Tx) and receiver (Rx) coils are designed to achieve stable power delivery across varying conditions. Even in the presence of frequency splitting, the proposed IPT system ensures robust power transfer through frequency modulation control. Furthermore, an infrared (irDA)-based communication protocol is implemented to maintain precise load power delivery, such as constant current-constant voltage (CCCV) battery charging, even under coil misalignment. A 2.2 kW IPT prototype for automated guided vehicle (AGV) wireless charging was fabricated and experimentally validated. The prototype achieved a maximum coil efficiency of 94.5% at a 35 mm coil distance and maintained coil temperatures below 60°C during a 2-hour AGV operation cycle, confirming the thermal stability and practical viability of the proposed design approach.