Controllable Rectifying Technology Of Four-Fhase Wound-Field Doubly Salient Generator In Bridge Rectifiers

Wound-Field Doubly Salient Machine(WFDSM)holds considerable merits of Doubly Salient Permanent-Magnet Machine(DSPM)and Switched Reluctance Machine(SRM)simultaneously.Owing to isolated DC windings on stator and doubly-salient structure without PM,WFDSM enjoys advantages of low cost and high reliability.Brushless DC generating can be easily achieved when diode rectifying circuits are adopted.Prevailing bridge rectifying topologies consist of Full-Bridge mode and Parallel-Bridge mode.Currently controllable rectifying technique has already been used in Full-Bridge mode,which can improve the generating power density of WFDSM by adding switchs on rectifiers in order to vary armature current.This paper consists of two main research contents.The first one focuses on Full-Bridge Rectifier(FBR)with Serial Compensation Capacitors(SCC)and Full-Bridge Half-Controlled Rectifier(FHR)with SCC.Controllable rectifying technique applied in Parallel-Bridge mode has been studied in another part.Firstly operating principles and modes of traditional FBR and FHR topologies are demonstrated.Generating characteristics of prototype under different field current are studied and several drawbacks under low field current are found.Voltage regulation rates of two topologies are high and rising ratios of output power from half-controlled rectifying are limited.FBR-SCC and FHR-SCC topologies are formed by adding SCCs between each phase winding of WFDSG and rectifiers.Calculating method of SCC value and how SCC influences operating modes of rectifying are introduced.The results of FEA and experiments show that because of SCCs,wider ranges of load current and better external characteristics are acquired under low field current.Half-controlled rectifying perfoms better and output power can be lifted in wide load ranges in FHR-SCC.How positive and negative half-cycle of phase current affect generating power is studied on the basis of analyzing different types of open fault in Parallel-Bridge Rectifier(PBR).Then a new Parallel-Bridge Half-Controlled Rectifier(PHR)topology which adopts APC strategy are introduced and compared with FHR.Simulation and experiment results of typical loads indicate that PHR can increase the peak value of positive half-cycle of phase current and decrease the peak value of negative half-cycle of phase current at the same time.Hence,armature reaction of demagnetization is inhibited effectively.Output power can be enhanced in wide ranges of load current under different field current values when PHR topologies are used.In addition,PHR keeps good load-bearing ability when one-phase open fault occurs.To conclude,this thesis has obtaind some basic charateristics of FHR-SCC and PHR topologies which will enrich existing research results of WFDSM controllable rectifying technique.