Research On Impedance Compression Network Of Very High Frequency Inverter System With Wide Load Range

Very high frequency power converters have excellent characteristics of high power density and fast dynamic response speed.They have broad application prospects and important research significance in fields such as aerospace satellite thrusters,medical imaging,and chip etching machines.However,the existing very high frequency inverters usually consists of a resonant network composed of passive components,and faces the problem of a narrow working load range.An intermediate matching network is always introduced to limit the impedance.However,the existing impedance control network can only adjust one of resistance or reactance,the resistance and reactance cannot be controlled at the same time.This paper analyzes the high-efficiency load range of three classic very high frequency inverter topologies,estimates the working modes and losses of Class D inverters under different loads.At the same time,combined with the existing parameter design schemes,the load sensitivity of the fully resonant Class E inverter and the fully resonant Class Φ inverter were analyzed in the frequency domain and the time domain.The optimal load impedance range of three inverters under the rated output power is obtained.According to the load interval obtained by the analysis,this paper further studies the design scheme of the impedance compression network in the very high frequency inverter system,and proposes an impedance compression topology combining the active network and the passive network.The passive two-port network and the active three-port network have been theoretically deduced and analyzed respectively,and finally,the topology selection,parameter design and control scheme derivation were completed,ensuring that the input impedance of the impedance compression network is always in the ideal region under a wide range of loads.According to the corresponding indicators,this paper combined Class D,Class E and Class Φ inverters to design three sets of 10 MHz inverter systems.The simulation results are consistent with the theoretical analysis,which proves the feasibility of the theoretical analysis.Finally,a very high frequency inverter system with 24 V input,50 W rated output,and 10 MHz operating frequency is built.The parasitic parameters in the circuit layout were optimized,and the control scheme at the MHz level was designed.The final closed-loop test results are consistent with the expected indicators.The system can accurately identify the load and realize closed-loop control under varying loads with amplitude between 40Ω～60Ω and phase between-45°～45°,and the range of impedance amplitude after adjustment is 15Ω～35Ω,and the phase change range is 20°～60°.Compared with the traditional structure,the overall work efficiency of the inverter system has been increased by 13%..