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Research status of dynamic wireless charging technology for electric vehicles at home and abroad

2023-11-28


Research institutions around the world are still continuing to conduct in-depth research on dynamic wireless power supply technology for electric vehicles and continue to promote the development of related theoretical and technical research.

Current status of foreign research

Foreign research teams such as the University of Auckland in New Zealand, the University of Tokyo in Japan, Oak Ridge National Laboratory in the United States, and the Korea Advanced Institute of Science and Technology (KAIST) have conducted a series of studies on the technical difficulties and key issues related to dynamic wireless power supply for electric vehicles, mainly focusing on System modeling methods, power conversion topology, optimal design of electromagnetic coupling mechanisms, and electromagnetic shielding technology. The University of Auckland in New Zealand and the German company Kangwen jointly developed the world's first wireless charging bus with a power of 30kW. They also developed a 100kW wireless power supply train prototype. The train track is 400m long. KAIST will use dynamic wireless charging technology to claim electric vehicles. for online electric vehicles. In 2013, two electric bus lines in Gumi City were put into operation. The total length of the lines is 24km, the transmission power is 100kW, and the efficiency is 850%.

The Oak Ridge National Laboratory in the United States conducts research on the coupling mechanism, transmission characteristics, dielectric loss, and electromagnetic radiation of dynamic wireless charging of electric vehicles. The ground transmitting device uses a full-bridge inverter and two primary windings in series. The experimental results show that the transmission Power and efficiency are greatly affected by the location of the electric vehicle.

The University of Tokyo in Japan proposed a maximum efficiency control method for the secondary side based on DC/DC converters. The coupling coefficient is estimated online in real time through the primary side equivalent impedance, and a feedforward controller is used to change the input duty cycle of the DC/DC converter to achieve maximum efficiency control. .

In terms of wireless power supply technology for rail trains, the Korea Railway Research Institute (KRRI) has designed and researched the entire wireless power supply system for rail trains, and built an experimental device with a power of 1MW and a track length of 128m. The coupling mechanism adopts a long straight guide rail at the transmitting end, and uses two small U-shaped magnetic cores to enhance the coupling performance. Since the rail is long and the inductance is large, in order to reduce the voltage stress of the capacitor, the capacitor is dispersed in the transmitting coil.

In addition, Germany's Bombardier is also at a relatively leading level in the field of wireless power supply for electric vehicles and trams. Due to commercialization reasons, its corresponding technical information is sparse.

 

Domestic dynamic wireless charging technology development trends

 

Domestic universities and research institutes have also successively carried out research work on wireless power transmission technology and applications. In October 2011, funded by the China Association for Science and Technology, the "Key Technical Issues and Application Prospects of Wireless Power Transmission" academic conference was held at Tianjin University of Technology. Salon, which was the first domestic academic conference in the field of wireless power transmission. Subsequently, the "Wireless Power Transmission Technology Seminar" was held in Chongqing in 2012, and the "Wireless Power Transmission Key Technology and Application Academic Seminar" was held in Guiyang in 2013. ", the "International Academic Conference on Wireless Power Transmission Technology and Applications" was held in Nanjing in 2014, and the "International Academic Conference on Wireless Power Transmission Technology and Applications" was held in Wuhan in 2015, demonstrating the good development trend and prospects of domestic wireless power transmission technology.

Several domestic universities that have carried out research related to dynamic wireless power transmission technology earlier include South China University of Technology, Hunan University, China University of Mining and Technology, Nanjing University of Aeronautics and Astronautics, Shanghai Jiao Tong University, Southeast University, Tianjin University of Technology, Chongqing University, and Chinese Academy of Electrical Engineering Institute, Southwest Jiaotong University, Harbin Institute of Technology, etc. Preliminary research in these universities mainly focuses on high-power power electronic energy conversion and topology design, magnetic coupling mechanism optimization design, system modeling optimization and control, system complex dynamic behavior analysis and control, energy and information synchronous transmission, load identification and foreign object detection In terms of technologies such as electromagnetic compatibility and electromagnetic shielding, research on relevant theories, technical difficulties and key issues has achieved certain results, and a principle prototype has been developed.

Southeast University conducted in-depth research on the impact of the size of the primary and secondary coils of dynamic wireless energy transmission on transmission efficiency and side shift, and proposed a method based on frequency control to optimize the system energy transmission efficiency. Tianjin University of Technology analyzed the impact of changes in the natural resonant frequencies of the transmitting coil and receiving coil of the high-speed train wireless power supply system in motion on the transmission efficiency of the system based on the coupled mode theory, and proposed a frequency tracking method with adjustable transmitter power factor. Control technology, and in 2013 proposed the idea of applying dynamic wireless energy transmission technology to high-speed railway train charging, and established a high-speed rail charging sandbox model, which received widespread attention. Chongqing University proposed a parameter identification theory to improve the problem of difficult adjustment of secondary side parameters during primary side control. On this basis, a system energy flow model was established.

Although research institutions around the world are still continuing to conduct in-depth research on dynamic wireless power supply technology for electric vehicles and continue to promote the development of related theoretical and technical research, there are still certain key technologies that need to be studied, including the design and optimization of magnetic coupling mechanisms, system robustness Research on rod control technology and electromagnetic compatibility technology to maximize system performance and ensure safe, reliable, stable and efficient operation of the system.

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