Research On Key Technologies Of High Frequency Power Electronic Resonant Converters

With the fast development of consuming electronic,data center,and renewable energy fields,strict requirements have been put forwards to system volume,weight,power density and efficiency.For switched mode power supply(SMPS),passive components such as inductor,transformer and electrolytic capacitor take the most volume and weight of power system,which greatly restricts the improvement of system power density.Higher operating frequency can reduce the stored energy of passive components within every period,leading to small volume and high power density.However,under high operating frequency,the switching loss,magnetic component loss and driving loss significantly increase,which become the development bottlenecks.To solve above problem,this paper investigates the key technologies related with high frequency power converters,such as high performance topology,optimal design method of magnetic components,and high efficiency driving strategy,the detailed research contents are shown as follows:Typical half bridge resonant converters,such as LLC and LCC,mainly focus on the soft-switching characteristics during switch turn-on transition.Under inductive resonant tank condition,the switch can achieve ZVS turn-on characteristics.However,large turn-off current leads to large turn-off loss,which restricts efficiency improvement in high frequency condition.To solve above problems,this paper proposes a family of high order resonant network with zero input impedance angle characteristics.Also,a CLCL half bridge resonant converter has been proposed based on corresponding resonant network,which operates with ZVS and quasi-ZCS characteristics.For the proposed CLCL half bridge resonant converter,the operating principles,voltage conversion ratio,and passive components design have been analyzed in detail.Meanwhile,existing modeling methods of resonant converters mainly focus on low order resonant network,which lack of guidance for high order converters.To solve above issue,this paper proposes a modeling method for CLCL high order resonant converter based on extended description function.Furthermore,a systematic modeling method for high order half bridge resonant converter is investigated based on models of resonant inductor and capacitor.For the proposed CLCL half bridge resonant converter,further efficiency improvement method and planar magnetic components design method are investigated.This paper analyzes the half bridge switch loss under ZVS condition and its dead time optimal design method.The switch loss characteristics of different materials and optimal selection method are demonstrated.Meanwhile,in high frequency converters,planar magnetic components can effectively reduce system vertical height and increase heat dissipation area.The copper tracks can be adopted as planar winding,providing good consistency.However once printed circuit board(PCB)is manufactured,the winding structure and parameters can not be adjusted.Effective design method for planar magnetic components should be proposed.This paper demonstrates effective design method for inductor and transformer based on response surface method(RSM)and modular layer model(MLM).A variable width winding structure and its optimal ratio are proposed in this paper,which can effectively reduce planar winding AC and DC resistance.The results of 1 MHz CLCL half bridge resonant converter verify the feasibility of proposed topology and optimal design method.Improving frequency to tens of MHz can further reduce value and volume of passive components.However,for the restriction of driving circuit,dead time adjustment and parasitic components control,half bridge structure is not suitable to operate at such high frequency,thus,single-switch resonant converter is investigated.This paper analyzes non-isolated converter based on Class inverter stage,L type matching network and resonant rectifier stage.The topology fully adopts the parasitic capacitance of switch and diode,reducing their impact on system operating mode.Also,T type matching network with resistive to resistive transferring function is proposed.Single-switch converter based on T type matching network can maintain soft-switching characteristics under variable load condition,improving system efficiency.High frequency self-resonant driving method based on drain-source voltage feedback network is proposed in this paper.Meanwhile,the basic resonant driving method suffers high loss.A high performance resonant driving method with shunt branch is proposed in this paper,which significantly reduces high frequency driving loss.The close-loop control strategy based on PWM ON/OFF method is demonstrated in this paper.For application fields with galvanic isolation requirement,a single-switch isolated converter based on air core transformer is proposed in this paper.Existing design methods of resonant rectifier are mainly based on parameter sweeping methods,where the parameters satisfying input and output characteristics requirement are decided by continually parameters adjustment and simulation results comparison.The design method consumes long time and lacks of quantitative analysis.To solve above problem,this paper establishes an accurate mathematical model of resonant rectifier,calculates the expressions of resonant components,analyses influences of input impedance angle and diode voltage stress,proposes an effective parameter design method.Also to reduce switch voltage stress,an optimal switch impedance network consisting magnetizing inductance,leakage inductance is proposed,where the switch voltage stress is reduced by controlling high order harmonics.To satisfy the requirement of transformer leakage inductance and magnetizing inductance,an air core transformer winding optimal design method is proposed.The relationship between winding structure and self-inductance/mutual-inductance is analyzed.The results of 20 MHz single-switch resonant converter verify the feasibility of proposed topology and optimal design method.