Research On Loosely Coupled Transformer For Rotating Wireless Excitation Power Supply

With coming of 21 st century,global energy consumption is increasing year by year,and demand for fossil fuels such as oil and coal is increasing,and world energy crisis cannot be ignored.Electric energy substitution is an effective way to solve current energy problems,and promoting development of electric energy can help reduce the emission of pollutants and improve energy efficiency.In the application field of electric energy,the motor is widely used as a device to convert electrical energy into mechanical energy.When power or voltage is too large,traditional motor because of the existence of brush,slip ring and so on,will cause bad contact of the system due to mechanical wear and other reasons,it can even lead to electrical sparks,ring fires,and burn motor excitation system.Current brushless DC excitation scheme mostly adopts semiconductor devices to realize electronic commutation,but due to inherent characteristics of the device,It's development is limited and will have a certain harmonic effect on the power grid.Electromagnetic speed regulating motor because of its simple structure,reliable operation,less control circuit,convenient maintenance and smooth speed regulation,stepless speed regulation no harmonic influence on power grids,has wide application prospect.Therefore,taking electromagnetic speed regulating motor as an example,the rotary wireless excitation system is designed to replace traditional conductor,brush and slip ring to improve reliability and safety of system.According to needs of project,rotary wireless excitation power supply is designed.Firstly,Current research status of existing brushless excitation system and the research status of the wireless power supply at home and abroad are briefly described.Taking excitation system of electromagnetic speed regulating motor as an example,design criterion of wireless excitation system is worked out,and basic structure of rotary wireless excitation system is determined.This paper also gives equivalent circuit of loosely coupled transformer,the core of rotary wireless excitation system.The equivalent magnetic circuit model of rotary loosely coupled transformer is established to analyze its principle characteristics of magnetic circuit model.According to the analysis,shortcomings of larger leakage inductance of windings in air gap condition have been improved.A PCB Winding structure applied to a rotary loosely coupled transformer is proposed,and comparison and analysis with traditional windings are made by using ANSYS MAXWELL electromagnetic field simulation analysis software.then the feasibility of the optimized scheme was determined according to the leakage flux and magnetic density cloud map analyses.Two types winding transformers were manufactured to perform LCR verification.Relation curve between coupling coefficient and air gap is drawn.Based on analysis of rotating loose coupling transformer's magnetic core structure,the improved multi U disk core structure is proposed,then this paper analyses common characteristics with traditional tank core structure,and feasibility of the multi U core structure is verified,Using 3D printing technology to design and manufacture related fixed structure.Multi U disk core structure and traditional tank core structure's comparison and analysis of simulation are carried out.S-S resonant compensation circuit is used to design circuit of wireless excitation power supply.Joint simulation of ANSYS SIMPLORER and MAXWELL is used to determine phase shift control mode of whole bridge as an experimental scheme,and relation curve of phase shift angle and voltage and current characteristic is obtained.The experiment platform is built by using digital controller DSP28335,switch tube drive circuit,high frequency inverter circuit and rectifier circuit.Then phase shifted full bridge control is used to compare and analyze proposed optimization design of loosely coupled transformers.