| With the development of wireless power transfer(WPT),WPT is widely used in many fields such as electric cars,electric toothbrushes,biomedical implant devices,LED or OLED drivers.Compared with the traditional power transfer,the aging,corrosion,leakage and other dangerous situations can be effectively avoided with wireless power transfer.So far,WPT can be divided into two types: inductive wireless power transfer(IPT)and capacitive power transfer(CPT).Compared with IPT,CPT has the advantages of low cost,small size,light weight,and the ability to transfer power in a metal environment.Therefore,capacitive power transfer technology has attracted more and more attention in recent years.LED has often been used as an alternative light source due to long life expectancy,high luminous efficiency,and no pollution.However,LED is a point light source with heat dissipation problem.Compared with LED,OLED is a surface light source without heat dissipation problem,and has the advantages of thinness,eye protection,and flexibility.Therefore,OLED has been increasingly used in people’s lives in recent years.At present,the inductive power transfer has been generally used to drive OLED with “one drive one load” mode.when the number of OLEDs increases,there will be complex topological structure,high cost,large volume,complex control,etc.Therefore,The capacitive power transfer is applied to drive OLED for the first time in this dissertation.A modular and cascade structure with “one driver multiple loads” for multiple OLEDs has been proposed.Since OLED is a current-sensitive element,a small voltage change can cause a large current fluctuation.the different OLED currents will have a big difference even with the same voltage of OLEDs.Therefore,the current imbalance is a series problem in the structure of “one drive multiple loads”.In addition,The power is transmitted with the electric field coupling in CPT system.The coupling distance and angle of the transmitting and receiving plates will have a great impact on the power transfer.Therefore,in order to tackle the issues of current imbalance and plate sensitivity,a daisy chain transformer structure and a bilateral LC compensation network are introduced in the proposed topology.The various coupling mechanisms in the CPT system have been analyzed in this dissertation.For the near-field coupling application of OLED,the plate coupling mechanism is selected for power transfer on the both sides.when the coupling mechanism changes in position and misalignment angle,The change trend of mutual coupling capacitance is analyzed;Secondly,by comparing the typical CPT compensation circuit topology,the half-bridge inverter circuit topology withbilateral LC compensation is selected to eliminate the sensitivity problem of the plates;Thirdly,the daisy chain transformer structure is used to solve the current imbalance problem between OLEDs;Finally,the fundamental harmonic analysis method is used to analyze the current balance characteristics and soft switching characteristics of the entire system.The simulation model of the system is established in the PSIM to verify the soft switching characteristics of the system and the current balancing effect under normal and faulty conditions.Combined with parameter design and theoretical analysis,a hardware experiment circuit was built to verify the correctness of simulation results. |
