Design, analysis and application of multi-channel and multi-pickup wireless power transfer systems

Abstract

Since 2007, wireless power transfer (WPT) has been extensively researched, enabling energy transmission without physical cords over long distances. Notably reliable, secure, flexible, convenient, and intelligent, this echo-making technology can facilitate wireless charging for different niches, for example, electric vehicles (EVs), mobile devices, medical implants, and household appliances. As practical applications continue to expand, the diverse needs of purchasers and varying industry principles introduce complexity and challenging considerations to this unique technology. Remarkably, among the applications mentioned above, multi-channel and multi-pickup WPT systems have undoubtedly become a future trend. Hence, this study mainly focuses on various technical aspects of multi-channel and multi-pickup WPT systems with emphasis on the multi-frequency compensation network, multi-channel constant voltage (CV) and constant current (CC) charging, cross-coupling cancelation method, and reactance elimination approach. The study of multi-frequency compensation networks aims to establish a multi-channel transmission path for a multiple pickups WPT system. The proposed topology can operate in the resonance stage with respect to different frequencies. Meanwhile, the demand power can be wirelessly transferred to different pickups concurrently while avoiding the utilization of space-costing transformers or extra transmitting coils. The study of multi-channel CC and CV charging presents a load-independent multi-frequency compensation topology to realize CC operation under various resonant frequencies on the primary side. Besides, a hybrid compensation network on the pickup side is also proposed to accomplish both CC and CV charging according to customers’ demands. Moreover, a communication-free approach for regulating the hybrid compensation network is also introduced. The study of the influence for the cross-coupling effect is to quantitatively analyze the cross-coupling effect for multiple receivers WPT systems from the perspective of power and efficiency. Meanwhile, a relevant cancelation method is also introduced to eliminate the cross-coupling effect. The proposed method holds sensorless, robust, and extensive operating range merits. Accordingly, the zero-phase angle (ZPA) operation can be guaranteed under the disturbance of reflected reactance. The study of reactance elimination aims to realize full-range ZPA operation under the significant disturbance of capacitance/inductance parameters, active regulation of operating frequency, and reflected caused reactance. The proposed power-electronic-based impedance sponge can serve as both inductive and capacitive characteristics to compensate for the reactive power, which holds the merits of seamless adjustments, absence of sensors, non-reliance on communication and feedback, straightforward control, and flexibility in high-order compensation. Finally, to verify and evaluate all the proposed multi-pickup WPT systems, theoretical analysis, numerical calculations, finite element method (FEM) simulations, and prototype experimentations are all presented to offer in-depth discussions for multi-frequency compensation, multi-channel CC and CV charging, cross-coupling cancelation method, and reactance elimination approach in multi-pickup WPT systems.