| More Electric Aircraft uses electrical power system to replace part of other second energy system, which can realize the electric management of aircraft. Auxiliary Power Units plays an important role in More Electric Aircraft, which is used to start the engine and supply electrical power to other airborne equipment dependently. Permanent Magnet Machines are promising for the Integrated Starter/Generator systems of Auxiliary Power Units in More Electric Aircrafts due to their high power density, high efficiency, improved reliability and fast dynamic response. Due to the high value of air gap flux density, PMSG should be connected to a rectifier to provide a DC power supply. In this thesis, the systematic study is carried out on the Permanent Magnet Synchronous Generators, and mainly focuses on the flux-weakening generator controls and the performance of the generator system fed by uncontrolled rectifiers.Firstly, the development history of More Electric Aircrafts and technical features of machines for Integrated Starter/Generator systems are presented in the thesis. Based above analysis, the latest research progress of flux-weakening control for high speed Permanent Magnet Synchronous Machines is presented.The standard unitary mathematical model of the Surface-mounted Permanent Magnet Synchronous Machines is analyzed in this thesis. Based above mathematical model, the machines' parameters' influences on the performance of flux-weakening control system are studied, and that can be a reference of designing Surface-mounted Permanent Magnet Synchronous Machines in flux-weakening modeThe high amplitude of back EMF of Permanent Magnet Synchronous Generators at high speed will lead to a problem of high voltage of DC bus. Based on theories of the flux-weakening control method which are used for Permanent Magnet Synchronous Motors, the flux-weakening control for Permanent Magnet Synchronous Generators is put forward in this thesis. The stability of voltage feedback flux-weakening generation control system is firstly analyzed by building its small signal model. And then a new method of flux-weakening generation control is studied, which uses a single current regulator instead of two. This control method can overcome the shortcomings of voltage feedback flux-weakening generation control due to the decrease of stability of system by the increase of the machine's speed.Uncontrolled rectifier is the most commonly used method for Permanent Magnet Synchronous Generators. The influences of machine's parameters to the external characteristic, power characteristic and short-circuit current is analyzed by building the mathematical model of generation systems. The core losses of Permanent Magnet Synchronous Generators fed by PWM rectifier and uncontrolled rectifier are also compared in this thesis.In the end of thesis, the theories based on above analysis are proved by simulations and experiments.The theory and technology basis for the power generation of Permanent Magnet Synchronous Generators are provided in this dissertation. In addition, the work of this thesis plays a positive role in promoting the application of Permanent Magnet Synchronous Generators in the field of aviation. |
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