Research Of The Dual-inductor Bridgeless PFC Converter Based On DSP

In recent years,with the support of policies,the electric vehicle industry has been developing rapidly,and on board charger(OBC)of the electric vehicle has become a re-search hotspot.As the front end component of the OBC,the research of Power Factor Correction(PFC)converter is of great significance.Firstly,from the topology point of view,a new dual-inductor PFC converter is stud-ied in this paper.Compared with the conventional Boost converter,it has the advantages of high voltage gain and low stress.However,the inductor value tolerance brings about the unbalanced current problem and oscillation problem,which not only increase the cir-cuit loss but also reduce the system stability.To address the above problems,a turn-off delay controlled current-sharing method is proposed to realize the two phase inductor cur-rent equalization by delaying the turn-off time of one of the MOSFETs,which expands the application range of the converter.A root locus based RC snubber circuit oscillation suppression method for the dual-inductor converter is proposed in this paper.The de-sign of the RC snubber is optimized to suppress the oscillation while reducing the loss generated.After solving the above two problems,this paper proposes a dual-inductor bridge/bridgeless PFC converter.Compared with the traditional Boost PFC,the duty cy-cle of the MOSFETs,the peak and RMS input current are effectively reduced,and the efficiency is improved.Secondly,from the control point of view,the totem-pole bridgeless PFC digital con-trol technique is studied in this paper.With the mass production of Si C MOSFETs,the Continuous Conduction Mode(CCM)totem-pole bridgeless PFC is an excellent solution for OBC.However,this topology suffers from current spikes near the input voltage cross zero point,which can significantly reduce converter lifetime and stability.In addition,the digital control system has a reduced phase margin compared to the traditional analog control,which requires more accurate modeling of the converter and more specific design of the compensator.To address the above problems,the working principle of CCM mode totem-pole bridgeless PFC is studied,and the current spikes near the input voltage cross zero point are analyzed,and a soft start strategy for high frequency and low frequency MOSFETs is given.With the strategy,the current spikes are suppressed and the system stability is improved.The different mechanisms of analog control and digital control in building the small signal model of the system are analyzed in this paper,and the impact of digital control sample-and-hold and delay on the system is studied in detail,which contributes to the application of the totem-pole bridgeless PFC.Finally,a dual-inductor DC/DC prototype,a dual-inductor bridge/bridgeless PFC model,and a totem-pole bridgeless PFC prototype are built in this paper.Among them,this paper introduces the principles of selecting components for the totem-pole bridgeless PFC,the design scheme of the Si C driver circuit,the model based design(MBD)method of DSP software control system,and the PFC double-loop experimental procedure.The hardware platform and software control algorithm are verified step by step through the DC/DC open-loop experiment,DC/DC closed-loop experiment,AC/DC single-loop ex-periment,and AC/DC dual-loop experiment.The final experimental and simulation re-sults verify the feasibility of the theoretical analysis and design scheme.