Research On Application Of Wireless Power Supply Technology In Electronic Transformer

Current transformer is an important equipment to realize measurement and protection in power system.With the continuous improvement of the voltage level of power grid,the traditional electromagnetic current transformer can not meet the needs of production because of the limitation of its sensing principle.Electronic transformer has become an ideal substitute for traditional current transformer because of its advantages of good anti-interference performance,high measurement accuracy and light weight.The high voltage side power supply of active electronic transformer is a difficult and technical problem in the research.Aiming at the problems of complex power supply,short service life and unstable power supply in the design of existing high-voltage side power supply,a new power supply scheme,namely wireless power supply technology,is proposed in this paper.Based on the principle of minimizing coil size and maximizing transmission distance,a wireless power supply device based on magnetic coupling resonance is studied and designed,which realizes stable power supply for high voltage side of electronic transformer.The main contents of this paper are as follows:1.Firstly,several main wireless power supply technologies are simply studied and analyzed,and the magnetic coupling resonance wireless power supply technology is adopted to supply the high voltage side circuit of electronic transformer.Based on circuit mutual inductance theory,this paper modeled and analyzed the magnetic coupling resonance wireless power supply technology,established the energy transmission model under PP topology,deduced the expression of output power,and further analyzed the influence of voltage,frequency and mutual inductance on power,which provided a theoretical reference for the parameter design of hardware circuit.2.Secondly,the overall design of the magnetically coupled resonant wireless power supply system is carried out,which mainly includes high frequency inversion link,resonant coil,resonant capacitor,rectifier filter and voltage stabilization link.According to the design index of the system,these links are analyzed one by one,and the parameters of the system are reasonably designed and optimized to ensure that the size of transmitting and receiving coils is minimized on the premise of obtaining stable power.Printed circuit board,complete the hardware circuit production.3.Finally,an experimental platform is built,and the power supply is tested experimentally.The output waveforms of the transmitter and receiver meet the experimental requirements.By testing the influence of distance and load on the transmission characteristics of the system,it is concluded that when the transmission distance is 5-11 cm and the load resistance is 100Ω-250Ω,the load can obtain more than 100 mW power,which fully meets the requirements of high voltage side power supply of electronic current transformer.Through the design of insulator,the prototype of the system is completed.Finally,the waveform diagram of the whole prototype experiment shows that the power supply can achieve long-term stable energy supply under the premise of guaranteeing effective insulation distance,which verifies the effectiveness of the design.