Research For Parallel Structure Hybrid Excitation Synchronous Generator

In the dissertation, research on parallel structure hybrid excitation synchronous generator (HESG) is given, with the aim at improving power density and enlarging adjustment scope of HESG. On the basis of review of permanent magnet synchronous machine(PMSM), electro-magnet synchronous machine(EMSM) and HESM, the theory and the method for improving PMSM's performance are given. The structures and operation principles of two synchronous generators are presented, and they are parallel structure HESG and radial structure HESG of magnet shunting type. The analyses and conclusions are validated by prototypes.The main contents and conclusions are listed as follows.Firstly, the research status of HESM at present was summarized. According to the magnetism potential connection manners, the classification of HESM is given, with the traits of HESM concluded. Also, the application of HESM is given.Secondly, the theory and the method for improving PMSM's performance were investigated. The geometry restriction condition of the rare earth magnet width in interior permanent magnet(IPM) was presented, and two definitions of"flux concentration function"are proposed. The relations between"flux concentration function"and the pole pair numbers of IPM synchronous machine are analyzed. The influences of rare earth thickness and non-magnetism bush thickness on machine performance were discussed. Furthermore, in order to reduce leakage flux and improve air gap flux, thickness of rare earth magnet in that position is optimized. Under the conditions that magnet thickness is constant, and the magnet width reaches maximum, with auxiliary magnet disappeared naturally, the optimized strategy of the structure of IPM synchronous machine was given.When IPM synchronous machine was used as AC generator for airplane and pole pair numbers are 2, the factors which influence the machine's performance were analyzed. The machine's performances under different ratios between rotor length and stator length were investigated. And the relations among machine's performance, machine's weight and pole pair numbers were discussed when IPM synchronous machine was used as airplane brushless dc generator.Thirdly, the configuration, the principle and the design method of the parallel structure HESG were studied. The design rules and the method for permanent magnet synchronous generator(PMSG) and electro-magnet synchronous generator(EMSG) in the parallel structure HESG were discussed. With the help of armature reaction theory, armature reactions of PMSG and EMSG in the parallel structure HESG are given under different load currents and excitation currents respectively. And three operation modes in the parallel structure HESG are proposed, and they are generator-motor state, generator-generator state and generator state. Also, the boundary conditions of three operation modes were defined. Then, three combination manners of PMSG and EMSG in the parallel structure HESG were discussed. According to EMSM's load characteristics, the calculation method of the excitation current in HESG was investigated. The above analyses are validated by experimental results.Then, a radial structure HESG with magnetism shunting type was proposed. With the help of equivalent magnetism circuit, its principle is analyzed. And the concept of magnetism shunting point, magnetism non-shunting point and load balance point were given. The principle and the method for improving adjustment scope of output voltage is discussed, and the suitable machine structure type is presented. Experimental results reveal that the above analyses are correct and the proposed strategy is feasible.Finally, the possible further research direction is given.