Research On Phase Module Combined Three-phase Single-stage Power Factor Correction Converter Based On Full Bridge Topology

Phase module combined three-phase single-stage PFC converter derives from three combined single-phase single-stage full-bridge PFC converter,it has better performance than single-phase converter.The combined PFC converter has many advantages while applied to middle and large power situations.However,this converter has the following problems: a special control strategy is needed for stable operating of the converter,voltage spikes exist across the bridge arm in single-phase module,and the output characteristics of the converter are investigated rarely.Hence,it is necessary to study these issues.The structure and control scheme of the combined PFC converter is introduced firstly in this paper.And the working principles of the single-phase module and the combined PFC converter are analyzed.On the basis,a shared voltage loop and independent current loop control strategy,which has limiter and double scaling factor,is proposed.Not only can the strategy achieve the goal of power factor correction,but also it realize power balance between three single-phase modules.It ensure the safe and stable operating of the converter.To solve the problem of voltage spikes in single-phase module,the forming mechanism of voltage spikes across bridge arm and the principle of active clamp circuit absorbing voltage spikes are analyzed.On the basis,the forming mechanism of drain-source voltage spikes of clamp switch is analyzed and the method that upper switches of bridge arms are operating in ZVS mode is proposed for this issue.The method of keeping clamp switch off while the input current is near the zero crossing is proposed to avoid the problem that voltage spikes across bridge arm cannot be absorbed in this stage.To avoid the inrush current of clamp switch while the input current is near the zero crossing,an improved active clamp circuit is proposed,which can solve the problem effectively.Some investigation on the output characteristics of the converter are done in this paper.The ripple at low power frequency of the combined converter is analyzed based on the analysis of output voltage ripple at two times line frequency of single-phase module.There is no two times line frequency ripple in the combined PFC converter,only six times line frequency ripple with low amplitude exists.Besides,the combined converter has faster output voltage dynamic response than single-phase converter.It is proved by means of the relationship between bandwidth of open-loop transfer function and dynamic response.Finally,on the basis of theoretical analysis and simulation verification,the experimental platform of phase module combined three-phase single-stage PFC converter is set up,and the above contents are verified.The experimental results fully verify the correctness of the theoretical analysis and the effectiveness of the proposed strategies or methods.