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

Abstract

Magnetic-resonance-based wireless power transfer (WPT) technology emerges with broad application prospects in many industrial areas. With its rapid development and popularity, modern industries have placed higher demands on technology in many areas, such as security, efficiency, controllability, and flexibility. Based on these issues, multi-coupling and multi-channel WPT systems have undoubtedly become the trend of future development. This study mainly focuses on the design, analysis, and applications of multi-coupling and multi-channel WPT systems, including single-input-multi-output (SIMO), multi-input-single-output (MISO), multi-input-multi-output (MIMO) and multi-frequency-channel systems. SIMO-based WPT systems consist of a single transmitter coil and multiple receiver coils. In addition to one-to-many power transmission, this type of system can also be applied to specially designed multi-coil receivers to achieve different objectives. Different practical prototypes are designed and devised for multi-functioning applications, including omnidirectional energy harvester for underwater WPT systems, electromagnetic field limiter for wireless charging for medical implants, etc. The study of multi-input WPT systems proposes a flattened transmitter matrix to realize practical optimizations for WPT systems. With the proper current control, both the strength and direction of the resonant magnetic field at the concerning area can be flexibly controlled. The research highlights four main areas: Firstly, a simple and handle magnetic field model is presented for multi-coupling WPT systems with the conventional pad-shaped coil. Considering the human exposure issues, the magnetic threshold determination method is proposed. Secondly, system modeling for different objectives, such as maximum power tracking or magnetic field limitations, is presented with accordant current algorithms. For a single output receiver, the system efficiency and magnetic limits are both considered. For multiple output receivers, the demand-customized power distribution is analyzed with a flexible weighting control. For high-temperature superconductor-based WPT systems, the optimal current algorithm is also developed based on its accordant AC loss modeling to realize better system performance. Thirdly, two different current synchronization methods are proposed to deal with the cross-coupling effect between the multiple coils in multi-input WPT systems. Their advantages and disadvantages are compared and analyzed. Finally, for implementation, the control logic is designed and proposed with high reliability. The multi-input system can be realized with a single power source and controller. To deal with the excessive amplitude difference of the multiple primary currents, the hybrid-frequency-pacing (HFP) is proposed to further improve the efficiency as well as the control procession for light-load operations of the converters. The study of multi-frequency-channel WPT systems to design a novel circuit component structure with multi-frequency properties and high embeddability. By using this component, traditional WPT circuit topologies can all be further expanded for multi-frequency operations. Here, a dual-frequency power adaption design is proposed for two frequency-channel applications. The prototype can operate well at both channels with no interferences. To evaluate the proposed advanced WPT systems, theoretical analyses, numerical simulations, and practical experiment tests are all conducted and presented to provide in-depth discussions and validations for multi-coupling and multi-channel WPT systems.