Harmonic Excitation Research For Radial And Axial Composite Magnetic Field Generator

At present, synchronous generators with the third harmonic excitation have been widely used in small and medium power sources and areas such as mobile power stations for troops as well. At the same time, the magnetic field of the third harmonic waves are influenced greatly bythe saturation level of magnetic field in the generator, the size of generators’ air gap and the shape of magnetic poles. On this account, the available designs for the third harmonic excitation are lack of accurate calculation, which leads to the present status that the non-load and load characteristics of generators are hardly to study. In this way, in the prototype process, factories try to solve the problem by changing harmonic windings numbers and magnetic poles’ shapes. However, the method obviously extends the development cycles and increases the costs for designs of new type of products.This paper analyses a novel type of generator—the radial and axial direction multiple magnetic AC synchronous generator by means of the computer simulation platform combined with the FEM-finite element method. The purpose is to study the basic characteristics of the generator and analysis a special excitation mode- the third harmonic excitation by computer simulation.This thesis uses Ansoft Maxwell electromagnetic finite element analysis software to simulate actual working condition of the generator. Firstly, this thesis sets up the equivalent model of the generator. Then, it studies no-load and load characteristics of this kind of generator. Thirdly, this paper analyses the excitation method and emphatically introduces the harmonic excitation method. In this way, the power generated by the third harmonic in the air gap can be derivated from the independent harmonic winding which is wingding outside the stator winding. The power rectifies through the external circuits before going into the excitation winding. On top of this, this paper also studies voltage adjustment rate when generator is without the voltage regulator.This essay analyses all the questions above from one to one. It gives simulation results in the form of graphics in the procession of preparation of this paper with specific textual description. Thus, the purpose of the paper to adopt harmonic excitation in the new generator as complex excitation realizes.This kind of excitation method can take good use of the third harmonic power in the air gap. Then, the generator with this kind of excitation system can omit the conventional generator excitation system required by usual system of excitation. Besides, the third harmonic winding don’t couple with the main stator windings, so the system can not only reduce the cost of excitation system but also improve the electromagnetic compatibility, and at the same time can reduce the influence connected with the third harmonic in the stability and security of the generator.