Study On Topological Optimization And Control Strategy Of Totem-pole PFC Converter

The AC-DC converter is the interface between the power network and the power electronic device.Due to the existence of large capacitance,the current waveform of the grid is pulse shape,which contains a large number of large harmonics.The introduction of active power factor correction technology in traditional rectifier can not only improve the input power factor significantly,but also restrict the harmonic current pollution for the grid and ensure the power supply quality of the power grid.The traditional active Power Factor Correction(PFC)technology using the rectifier bridge to convert the input voltage to the pulsating direct current,and then the PFC purpose is achieved through Pulse Width Modulation(PWM)control of the power electronic switching device.Because of the existence of the rectifier bridge,the efficiency of the traditional PFC converter in the higher power level is restricted.Therefore,in order to develop a more efficient PFC converter,more and more researches are focused on eliminating the bridge PFC technology.This article through comparison and detailed analysis of the present representative four bridgeless PFC circuit,the number of common mode noise and main components based on selective advantage the most obvious Totem-pole Boost type bridgeless PFC circuit in-depth research.By analyzing Totem-pole Boost PFC converter the equivalent circuit of each phase in discontinuous conduction mode(DCM)conditions,then further deduced under the condition of fixed duty cycle of the converter input current and power factor of mathematical expressions,and found that the power factor will be significantly reduced with the increase of power grid voltage.This paper using the method of Taylor expansion to fitting the duty ratio of the predictive control method,which is applied to Totem-pole Boost PFC converter.The PF value is approximately 1 in the range of wide input voltage,and it has the advantages of small output bus voltage ripple and high efficiency.Finally,the effectiveness and feasibility of variable duty cycle control strategy is verified by an experimental prototype with full load output of 100W.Due to the defect of high current stress in the DCM Totem-pole Boost PFC converter,the application of the converter in high power is limited.This paper introduces two phase interleaved technology to Totem-pole Boost PFC converter,analysis the working principle and control strategy of two-phase interleaved Totem-pole Boost PFC converter under the DCM condition,and the correctness of the theory is verified by building a simulation model and an experimental prototype with full load output power of 245W.Finally,by comparing the efficiency and PF value curves of the four PFC converter topologies,the superiority of the interleaved totem PFC converter is further highlighted.