Buck Cycloconverter Type Single-stage Multi-input High-frequency Link Inverter With Simultaneous Power Supply In Series

The depletion rate of traditional fossil energy is accelerating,which has a great impact on the earth's environment,but also limits the future development of human beings.Reducing the use of coal,oil and other traditional fossil energy and improving the utilization rate of clean energy is a feasible way to reduce pollution.Clean energy sources are rich in resources,widely distributed,convenient to use,less pollution to the environment,and can adapt to the ecological environment.However,the single new energy power supply has some defects,such as instability,discontinuity,and being greatly affected by environmental factors.For the sake of overcome the above defects and realize the priority and full utilization of new energy,multi-input inverter with combined power supply of multiple new energy is needed.On the basis of discussing the development and research status of traditional two-stage multi-input inverters and analyzing its circuit structure,volume and weight,this paper proposes a single-stage multi-input Buck cycloconverter type high-frequency link's inverter with series and simultaneous power supply.The key problems of full bridge circuit topology,unipolar phase-shifting SPWM master-slave power distribution energy management control strategy,steady state principle characteristics(high frequency switching process,duty cycle derivation and external characteristics,etc.)and main parameter design are analyzed.On this basis,the simulation analysis,prototype design and experiment of the multi-input inverter are carried out.The circuit structure of single-stage multi-input full bridge Buck cycloconverter type high-frequency link's inverter with series and simultaneous power supply is composed of multiple series simultaneous selection power switch circuit,a high-frequency inverter circuit with single-input and single-output,a high-frequency transformer,cycleconverter and an output filter.This kind of multi-input inverter adopts unipolar phase-shifting SPWM master-slave power distribution energy management control strategy.The bipolar multi-level SPWM wave is generated by the phase-shifting of the right arm to the left arm of the high-frequency inverter circuit,and then demodulate it into unipolar three-state multi-level SPWM wave through the high-frequency transformer isolation transformer and cycleconverter.The functions of master-slave power distribution of multiple input sources,output voltage stability and smooth switching between different power supply modes are realized.The high frequency switching process of single-stage multi-input full bridge Buck cycloconverter type high-frequency link's inverter with series and simultaneous power supply is studied in depth under two power transfer modes:forward transfer energy(u_o>0,i _Lf>0)and reverse feedback energy(u_o>0,i _Lf<0).The duty cycle expression of multiple input sources is derived,and the four quadrant characteristic curve is drawn according to the expression.The influence of common mode voltage on the circuit is analyzed,and the common mode interference suppression strategy of input source is given.The multi-input inverter realizes bidirectional symmetrical magnetization of high frequency transformer,ZVS of the front arm of inverter bridge power switch and ZVS of cycle converter switch.The small-signal circuit model and small-signal mathematical model of a single-stage multi-input full bridge Buck cycloconverter type high-frequency link's inverter with series and simultaneous power supply are established,which lays a theoretical foundation for the design of regulator.The voltage stress and current stress of each power switch are derived,and the design criteria of main components such as high-frequency transformer and input-output filter are given.Designed and developed a 1k VA 240-360VDC/220V50Hz AC single-stage multi-input full bridge Buck cycloconverter type high-frequency link's inverter with series and simultaneous power supply prototype.Simulation and experimental results have shown that the proposed multi-input inverter realizes the high-frequency transformer bidirectional symmetrical magnetization,the high-frequency inverter bridge lead bridge arm zero voltage switching and the lag bridge arm zero voltage switching,ZVS commutation of cycloconverter.The proposed multi-input inverter has the advantages of single-stage power conversion,high-frequency electrical isolation between output and input,wide duty cycle adjustment range,small output voltage ripple,high conversion efficiency,small volume and low cost,etc.,which validates the feasibility and advancement nature of the proposed circuit topology and energy management control strategy.And it has a good application prospect in new energy power supply.