Dynamic Wireless Power Transfer System for Indoor AGV With a Distance-Measurement-Based Position Detection Technique

Inductive dynamic wireless power transfer (WPT) for moving objects, such as automated guided vehicles (AGVs), has become of special interest. For efficient and leakage-flux-reduced WPT for an AGV, only one transmitting coil (or a small array of transmitting coils) should be energized simultaneously; therefore, the position of the receiving coil should be detected precisely. Conventional AGV position detection techniques are often based on position detection sensors (magnetic or optical) placed near or inside each transmitting coil. However, this approach is expensive, relatively unreliable and it has high level of complexity. Therefore, in this study, a less expensive, more reliable and less complex technique for position detection of low-speed and moderate-speed AGVs (speed <1.5 m/s) is proposed and verified experimentally using a scaled-down AGV prototype. The technique is based on the ultrasonic distance measurement of a moving AGV to energize the correct transmitting coil. As shown in the comparative measurements, the performance of the dynamic WPT system with the proposed detection technique for low-to-moderate-speed AGVs is similar to that of the dynamic WPT system with conventional position detection techniques. However, the cost and level of complexity of the position detection system are moderately lower and the proposed position detection system is immune to optical radiation and magnetic fields. To extend applications of the ultrasonic techniques to high-speed AGVs, another AGV position detection technique based on the combined application of the maximum transmitting coil current detection and ultrasound-based AGV motion direction detection was also proposed.