Research On Constant Voltage Output Of Dynamic Loads In Magnetic Coupling Wireless Power Transfer System Based On AC-AC Envelope Modulation

Magnetic coupling wireless power transfer(MC-WPT)technology is a technology that uses electromagnetic induction technology to achieve wireless transmission of electric energy,which has broad market prospects and scientific research value.The traditional MC-WPT system has problems such as complicated control,low power factor,high cost,low power density,and low system efficiency,which have affected the development and promotion of wireless power trans fer technology.For this reason,MC-WPT technology based on envelope modulation came into being,this technology combines load power,energy form,and input electrical energy form,removes DC voltage regulation and large capacitor filtering links,and modulates low-frequency power to high-frequency electrical energy in the form of an envelope to realize wireless power transfer.This paper takes the voltage-type envelope modulation MC-WPT system as the research object,and conducts research around its dynamic load AC regulated output.By analyzing the existing resona nce compensation topology of the MC-WPT system,the advantages and disadvantages of the low-order compensation topology and the high-order compensation topology are explained separately,and the voltage-type compensation topology is used as the carrier of the envelop modulation MC-WPT system in the following text.By optimizing the parameters of the two voltage-type compensation topologies,the purpose of improving the stability of envelope modulation is achieved,and the effect of the regulated output of t he envelope modulation MC-WPT system is further improved.The main research contents are as follows:(1)The principle analysis of envelope modulation MC-WPT system.For the envelope modulation MC-WPT system,first introduces the modulation concept in the communication principle,thereby deriving the basic principle of envelope modulation;Taking the series/series AC-AC MC-WPT system as an example,the envelop modulation MC-WPT system primary side envelope modulation and secondary side envelope demodulation process are described in detail;Finally,the key technology of the envelope modulation MC-WPT system is explained.(2)Proposal and optimization of series/parallel MC-WPT system full resonance compensation method.When studying the parameters of the SP type compensation structure of the MC-WPT system,it was found that the secondary side of the traditional compensation method did not resonate.O n this basis,a full resonance compensation method is proposed.Under the premise of adding no components,the calculation method of the compensation capacitance is obtained through the system impedance analysis,so that the primary and secondary circuits are in resonance.At the same time,an optimization method is proposed for the shortcomings of the full resonance compensation method.The results show that the system efficiency,power and power factor are better than traditional compensation methods under the full resonance compensation mode.(3)Series\series MC-WPT system parameter optimization.Through impedance analysis of the primary side series and secondary side series resonance compensatio n topology,the parameter characteristics of each link are deduced.It has the characteristics of constant current on the primary side and constant voltage output on the secondary side.Secondly,the frequency stability range of the system with respect to the resistance load and transmission distance is derived from the primary side impedance,and the existence of the constant frequency domain is found.In this domain,the natural oscillation frequency of the system is always equal to the resonance frequenc y,and the system frequency stability is not affected by resistive load and transmission distance.(4)Design of AC Voltage Stabilized O utput C ircuit for Dynamic Load of MC-WPT System with Envelope Modulation.Based on the previous parameter optimization research,the series\series compensation topology is chosen as the carrier of the envelope modulation MC-WPT system dynamic load voltage stabilization output circuit.Aiming at the problems of too many cascade links and complicated control of traditional vo ltage stabilization methods,and the influence of input power fluctuations on envelope modulation,an AC-AC Boost converter is added on the primary side to achieve constant primary current,so as to realize the regulation control of the output AC voltage under dynamic load.The results show that the designed voltage stabilization system has a good voltage stabilization effect,few cascade links,simple control,low harmonic content on the input side of the system,and high power factor,which can reduce the harm to the power grid.