Research On Wide Input Voltage And High Efficiency Interleaved Boost PFC Converter

With the development of national economy and technology,the demand for AD-DC converters is increasing day by day.How to achieve a series of requirements such as high power factor,low input current distortion,and high efficiency of AC-DC converters under wide input voltage conditions has been a research hotspot in recent years.At the same time,for high-power applications,the application of multi-channel interleaved parallel technology is increasingly widespread.Because the boost inductor of the Boost PFC converter is located on the input side of the converter,the input current will not change suddenly,and the high frequency harmonic components of the input current can be effectively suppressed.The research object of this paper is a four-channel interleaved parallel DCM Boost PFC converter.First,this article analyzes the working principle of the four-channel interleaved parallel Boost PFC converter,uses the time average equivalent method to establish the four-channel interleaved parallel Boost converter CCM and the DCM equivalent circuit model,and discusses the effect of the inductance difference on the CCM.The current distribution of each channel of the Boost converter is interleaved in parallel with the DCM.Analyze the reasons for the low power factor of the four-channel interleaved parallel DCM Boost PFC converter under constant duty cycle control and the large input current distortion.The variable duty cycle control is applied to the converter,and the effects of constant duty cycle control and variable duty cycle control on the steady-state performance of the converter are compared and analyzed.Secondly,analyze and calculate the loss of the four-channel interleaved Boost PFC converter in parallel.For the unit converters in the interleaved parallel structure,frequency control is adopted to reduce the transmission loss when the instantaneous input power is low.Depending on the output power,the number of unit converters that work is controlled to improve the efficiency of the converter in the full power range.At the same time,the influence of the phase difference of the drive signal of each channel in the phase number control on the input current ripple is discussed.At the same time,aiming at the inrush current generated when the Boost PFC converter is started,compared the increase loop impedance method and the thyristor pulse trigger method,the circuit structure and working principle of the two start inrush current suppression methods are analyzed in detail,and the thyristor pulse trigger surge suppression circuit is designed.The four-channel interleaved parallel DCM Boost PFC converter has parallel usage scenarios.According to the requirements of the converter parallel current sharing index,this article analyzes the output characteristics of the converter during operation,and compares several commonly used current sharing strategies to improve the output impedance method.,And elaborated the design process of the improved output impedance method.Finally,build an experimental prototype of a DCM four-channel interleaved parallel Boost PFC converter with an input voltage of 85～264Vac and an output power of 1000 W.The use of variable duty cycle control can effectively improve the power factor of the converter,reduce input current distortion,and reduce output voltage ripple.It is verified that the segmented frequency control and phase number control are beneficial to improve the efficiency of the converter.Experiments were carried out on the start-up impulse current suppression by increasing the loop impedance method and the thyristor pulse trigger method.Both methods have obvious suppression effects on the start-up impulse current.When the single converter is in steady state operation,the efficiency of the interleaved and parallel Boost PFC converter is about 97% under the conditions of rated voltage input and full load,realizing high efficiency.At full load,when multiple converter units are running in parallel,the current unevenness is less than 5%,which meets the requirement of parallel current sharing of multiple converters.