Research Of The CPT Technology For Contactless Sliprings

Rotary equipments are widely used in the fields of aerospace,national defense,new energy and so on.Mechanical sliprings,as the widely adopted solution,is undesirable due to their inherent friction and associated wear and tear.Wireless power transfer(WPT)technology can achieve contactless electric energy and information transmission,and solve the problems of the traditional slipring.The main WPT technologies applied in contactless sliprings include Inductive Power Transfer(IPT)and Capacitve Power Transfer(CPT)technology.CPT transfers the energy through the electric field between the completely separated plates.Because of the advantages of light weight,low volume of the energy coupler,CPT has become the research hotspot of the current WPT technology.Firstly,this thesis expounded the current research of CPT system,introduced the advantages of CPT comparing with IPT technology and performed the key technology analysis.Secondly,the universal equivalent circuit model of the capacitive coupler is established as well as the capacitive coupling mechanism.It is found that CPT duals with IPT and thus the characteristics of the CPTsystem can then be obtained due to the duality.Then,dual to the four basic topology of IPT,the basic topology of CPT is then proposed.The voltage transfer ratio,current transfer ratio and input impedance are deduced by fundamental wave analysis.The voltage gain,current gain and input zero phase angle independent of load are obtained.Because of the small coupling capacitance,CPT system is easy to be mistuned.Therefore,LC network is introduced in the basic topologies as well as the steady-state characteristics analysis.Finally,the circuit design,simulation and experiments of a 100 W CPT converter,are given verifying the correctness of the theoretical analysis.The efficiency of the converter operating at 1MHz with 100 W output is 86.4%.