Font Size: a A A

Research On Topologies And Active Soft Switching Technologies Of Semi Bridgeless Boost PFC Converter

Posted on:2017-05-14Degree:DoctorType:Dissertation
Country:ChinaCandidate:W HuFull Text:PDF
GTID:1362330566474326Subject:Electrical engineering
Abstract/Summary:PDF Full Text Request
Active power factor correction(APFC)technology plays a key role in reducing harmonic pollution on grid and improving the power utilization.The bridgeless boost PFC converter as one of the important topologies of APFC technology greatly reduces the conduction loss.However,its inherent large common-mode noise makes it has great limitation in industry application.Among the many improved topologies of the bridgeless boost PFC converter,the semi bridgeless boost PFC converter has the very important research value for the advantage of the low conduction loss,the small common-mode noise and suitable for the continuous current mode(CCM).Therefore,the semi bridgeless boost PFC converter and its active soft switching technologies are preferred and studied in this dissertation,the main contents and original contributions are as follows:The flow direction of the inductor current of the semi bridgeless boost PFC converter is analysed,where the design scheme on the average current control method of it is given.To overcome the disadvantage of the original converter such as the difficulties of the inductor current detection and the complexity of the control circuit,an improved semi bridgeless boost PFC converter is proposed in this dissertation.The proposed converter can simplify the inductor current sampling strategy significantly.The influences of input voltage on the duty ratios of each power devices are analyzed,the current expressions of the power devices in any line cycle are deduced,and the power losses of the converters are contrastive analyzed,that show the proposed converter can maintain the efficiency while optimizing the control circuit design.The feasibility of the design scheme and the correctness of the power losses analysis are verified by the simulation and the experiment at wide line and full load.The zero-voltage transition(ZVT)technology is a hot area of reaearch among the active soft switching technologies.How to reduce the switching loss of the auxiliary switch is the key to improve the efficiency of the ZVT semi bridgeless boost PFC converter.The existent methods that the auxiliary switch turned off under soft switching in the ZVT boost DC-DC converters are analysed.To introduce a resonance and energy feedback circuit into the active snubber,a semi bridgeless boost PFC converter with soft switching auxiliary switch is proposed in this dissertation.The power loss of the auxiliary switch is reduced significantly.At the same time,the proposed converter realizes zero-voltage switching(ZVS)for the main switches and switching naturally for the boost diodes,and the resonant energy can feed back to the load.The influences of the input voltage and load on soft switching for the converter are analyzed,the constraints under soft switching for each power devices are deduced.On the basis of it,the parameters of the active snubber are deduced.The feasibility of the design scheme and the correctness of the theoretical analysis are verified by the simulation and the experiment at wide line and full load.The turn off characteristics of the auxiliary switch under zero-current switching(ZCS)is better than which under soft switching,and the turn-off loss of the auxiliary switch is reduced to zero theoretically.The existent methods that the auxiliary switch turned off under ZCS in the ZVT boost converters are analysed.To improve the energy release circuit by a controlled voltage source,and introduce it into the active snubber,two types of semi bridgeless boost PFC converters with quasi-ZCS auxiliary switch are proposed in this dissertation.The power losses of the auxiliary switches are further reduced.In the same way,the proposed converters realize ZVS for the main switches and switching naturally for the boost diodes.The constraints and scopes under soft switching for the converters are deduced,and the simulation and the experiment at wide line and full load are given.The last converters have two defects: the auxiliary switches are only operated at quasiZCS,and the magnetizing energies of transformers are all consumed.The existent methods to further reduce the power loss of the auxiliary switch in the ZVT boost converters are analysed and the design methods are extended in this dissertation.The design principle to realize the auxiliary switch under ZCS and the magnetizing energy feedback by using LCD clamp circuit is proposed,and two types of semi bridgeless boost PFC converters with ZCS auxiliary switch are deduced.The power losses of the auxiliary switchs are minimized.In the same way,the proposed converters provide all the soft switching functions as same as the last converters,and realize most of the magnetizing and leakage energies feedback to the load.The constraints and scopes of the auxiliary switches turn-off at ZCS,and the theoretical value of magnetizing energy feedback in any switching cycle are deduced,the simulation and the experiment at wide line and full load are given.The converters can further improve efficiency than the last converters.
Keywords/Search Tags:semi bridgeless boost PFC converter, inductor current sampling strategy, zero-voltage transition, zero-voltage switching, zero-current switching, magnetizing inductance, magnetizing energy feedback, LCD clamp circuit
PDF Full Text Request
Related items