The Research And Application Of New Model Commutation Transfomer

In 1948,the normal transistor invention has aroused electronic industry revolution ,and the semiconductor device has applied to the low power field first,such as:communication , the computers for information processing etc.After USA GE develops the first industrial thyrister successfully in 1958,the semiconductor device power has expanded greatly. The electric energy transforming and controlling realizes usually by the whorl converter or motionless ion converter,but the converter is composed of the semiconductor device now,it indicates that the electric power electron technology comes into being. With uninterrupted development of the electric power electron technology and the control technique,its application already goes deep into to the commercial run and the social life,including:Electrochemistry,direct-current drive,exchange drive,electroplating and electromachining , the electric motor magnetization,mid-range frequency induction heating,direct-current transmission and reative-load compensation etc.So that it becomes the key technology in conventional industry and high or new technology field.However the negative effect has been also gradually obvious.Because the electric power electronic devise'switching action has caused large amount of harmonic and subharmonic components pouring into electric network,so result in the distortion of voltage and current wave form of the AC network . semiconductor device have replaced the traditional transformer that generates harmonics for its nonlinear ferromagnetic material of becoming the mainest harmonic source. The conventional commutation transformers are not able to suppress the harmonics because of the defect of its structure,The harmonics still affects AC network through the transformers。The new model commutation transformer has the fuctions of harmonic suppression and reactive-load compensation,but the conventional transformesr have not.So the new model commutation transformer has important research value. The thesis has done the following aspect job mainly:(1)Firstly,describes the development of commutation transformer and the current situation on home and abroad,specially the commutation transformers being used for electrochemical industry,the more detailed explanation has been given.(2)Introduces the new model commutation transformer operating principle and the structure characteristic. For analyzing the new model commutation transformer's operating principle easily,one 13 KVA dry-type transformer is designed theoretically. According to the request that equivalent impedance of the centre winding should almost be "zero impedance ",several parameters of the transfomer are optimized including: cross section of iron core, specification standards of the windings'wire,gas length between two windings and reactance height.(3)The new model commutation transformer centre winding links with the wave filter groups,which decides whether the new model commutation transformer can shield the harmonics or not.Here two main wave filtering schemes are designed in the thesis , one is a joint monotonous wave filter,the other is a double tuning wave filter . several combinations among the 5th,7th,11th and 13th key harmonics have carried out when the double tuning wave filter is designed. The simulation models are built in MATLAB software according to the parameters of the different filtering skemes.We can observe the effect that the harmonics are suppressed obviously by simulating. By the contrast of monotonous wave filter and double toning wave filter in technical economy,the former skeme is more rational . Of coure the double tuning scheme is also satisfied the request.(4)Introduces the classical electromagnetic field theory,especially desribes Maxwell field equations and the border conditions about the electromagnetic field. The Finite Element Method is represented briefly and the softwares about electromagnetic field analysis are listed. The new model commutation transformer 3-D finite element method simulation model is built by the Maxwell software which is produced by USA Ansoft Corp. The sizes of the simulation model is same to the sizes of the new model commutation transformer. The leakage reactances of the three windings are calculated by the magnetostatic field module of the simulation software, the results are very approximate to the values of the leakage reactances designed.And have analysed Lorentz force of the three winding and the magnetic flux density of the iron core. The transient electromagnetic field module is applied to simulate the situation that the exciting sources of the windings are AC souces. We can observe the changes of the Lorentz force on the three windings and the magnetic flux density of the iron core,and can get their curve graphs in the setted time.In short,the research to new model commutation transformer should be all-round. After optimizing the commutation transformer,the equivalent short-circuit impedance of the centre winding is very small,and almost approximate to zero.but relatively the equivalent short-circuit impedance of the net-side winding is very big .Thus the new commutation transformer can shield the harmonics effectively.What's more , after optimizing the commutation transformer,the heights of the reactance of three windings are reduced,so the materials are saved and the cost is low down.