| In the communication modular power supply,high efficiency,high power density and high reliability are important development trends of application,and also meet the economic requirements of sustainable development,low-carbon and energy saving.Switching power supply is widely used in the field of communication power supply with the advantages of high efficiency,light weight and wide voltage stabilizing range.The communication power supply is generally divided into front and rear converters.The front stage is power factor correction（PFC）and the rear stage is DC to DC（DC/DC）conversion.This paper mainly studies the front stage PFC circuit.High efficiency,low cost and high reliability are also largely related to the selected topology and devices.Among many bridgeless boost PFC topologies investigated,totem column boost PFC topology has the advantages of less devices,low conduction loss and low common mode noise.It can be used in high-efficiency AC/DC communication power supply.Therefore,totem column boost PFC topology is the main research object in this paper.In terms of switch selection,the Si based MOSFET process is mature,which is conducive to achieve high efficiency and low cost.However,gallium nitride（GaN）,as the third generation semiconductor,has more development potential.At present,GaN manufacturers rarely provide corresponding simulation models,so it is necessary to study the modeling of GaN HEMT（high electron mobility transformer）.This paper studies a modeling idea suitable for almost all GaN HEMTs.Aiming at the serious reverse recovery problem of MOSFET body diode when Si MOSFET is used in totem pole boost PFC topology and working in CCM（current Co tinous mode）,this paper studies the working principle and control method of totem pole topology in CRM（critical conduction mode）,which is easier to realize the soft switch in Totem pole circuit;Gan switching devices are used to improve the switching frequency,so as to achieve high power density.However,for this topology,the input current in CRM mode has large current ripple.Therefore,this paper studies the control strategy of two circuits interleaved in parallel,which is conducive to improve the power level and efficiency under light load.In terms of control strategy,firstly,the working principle of totem pole boost PFC topology is deeply studied,then the small signal model of the topology is derived,and then the power level transfer function of the system is obtained;The theoretical design method of current inner loop and voltage outer loop is given.By observing the baud diagram of open-loop transfer function and the effect after compensation,the appropriate compensator parameters are determined.In the realization of zero voltage switch（ZVS）,when Vin>Vo/2,totem pole boost PFC topology can only realize Valley switching（VS）.In order to pursue lower switching loss,the core idea of TCM（triangular current mode）mode is introduced into the adjustment of Freewheeler.After analyzing the working principle of zero current detection（ZCD）,the ZCD signal detected by auxiliary winding is combined with the method for predicting the zero crossing time of inductance current,which is called TCM scheme in this paper.The calculation formula of the on-time adjustment of the Freewheeler and the resonance time formula before the main frequency tube is turned on in TCM mode are deduced,which provides a theoretical basis and scientific calculation method for the totem column boost PFC topology to realize soft switching in the full input range.In this paper,the main parameters of totem pole boost PFC converter,the hardware circuits of power board,half bridge sub card and control board are designed in detail.DSP TMS320F280049C is used as the main CPU and the program is written.Finally,the simulation model and the experimental prototype of 1.6kW two-way staggered parallel totem pole PFC circuit are built.The feasibility and effectiveness of the theoretical analysis and design method in this paper are verified by simulation and experiment. |
PDF Full Text Request