Research On Three-phase Resonant Pole Soft-switching Inverter

The application of soft-switching technology in power and electronic inverter can not only improve the efficiency,power density and stability of inverter,but also reduce the electromagnetic interference and noise pollution caused by high power and high frequency of power and electronic converter.At present,the research of soft-switching inverter mainly focuses on resonant dc-link inverter and resonant pole inverter.Resonant pole soft-switching inverter has attracted the attention of many scholars because of its high dc voltage utilization ratio.In order to further improve the conversion efficiency of resonant pole soft-switching inverter,this paper studies the energy-saving of resonant pole soft-switching inverter.In the second chapter,a three-phase energy-saving resonant pole soft-switching inverter with transformer assisted converter is presented.The circuit adopts the space vector pulse width modulation(SVPWM)method,and only the working state of one phase bridge arm is changed in one switching cycle,that is,only the auxiliary resonant circuit of one phase bridge arm is required to work.There is no voltage divider capacitor in the auxiliary circuit,so the neutral point potential is not stable.The control of auxiliary circuit is simple.When the inverter enters the dead-zone state,the auxiliary switch is opened.It is not necessary to open the auxiliary switch to charge the resonant inductor before open the main switch.There is no circuit that transformer magnetization current form a stable circulation in the auxiliary circuit.The magnetization current can be naturally attenuated to zero in each switching cycle,and the transformer realizes demagnetization reset.The main switch and the auxiliary switch can complete the ZVS and ZCS respectively.Second chapter proposed inverter topology,auxiliary circuit has transformer,and the auxiliary device is more,the corresponding increase ofthe circuit loss,does not favor the inverte efficience,in orde to solve this problem,thirdth chapte puts forward the small and medium-sized three-phase high-frequency and energy-saving resonant inverter,the structure of auxiliary resonant circuit is simple,the auxiliary device greatly reduced and no transformer,main switch and auxiliary switch to achieve zero voltage soft-switching,improve the efficiency of the inverter.The third chapter proposed inverter topology,the main switch can't achieve zero current turn off,so it can't be applied to high power field with IGBT,the fourth chapter puts forward a new type of three-phase resonant inverter,main switch can complete the zero voltage soft-switching and zero current turn off,the main switch realize the zero-loss of switch,which is applied to high power field,and MOSFET and IGBT can be applicable to the main switch of inverter,broadening the selection of main switch device.This circuit can realize the zero-loss of main switch and further improve the inverter efficiency.In the part of theoretical analysis,the principle of soft switch inverter in different working modes is described in detail.Because there are many energy storage elements in the soft-switch inverter,the dynamic behavior of the soft-switching inverter is complex and time-varying with high dimension.In view of the above difficulties,this paper combines the method of differential equation and phase-plane analysis to study the dynamic characteristics of the inverter,discusses the soft switch design rules and parameter design process,also discusses the mathematic model of auxliary resnant circuit loss,and finally uses MATLAB software for circuit simulation.Simulation results show that the proposed three soft-switching inverters can realize soft-switching and improve inveter efficiecy.