Design Research For Hybrid Excitation Synchronous Generator

The rotating rectifier brushless generator, a kind of electrical magnetic synchronous generator, is widely used in aircraft power system at present. However, this kind of generator has disadvantages in its somewhat complex structure. Its reliability is therefore affected. Meanwhile, the application of the permanent magnet synchronous generator, which is simple in structure, high in efficiency and reliability, is limited by the difficulty to adjust its output voltage.Hybrid Excitation Rare Earth Permanent Magnet Synchronous Generator, (simplified as HESG), can regulate the output voltage. Our research project aims at the development of this hybrid excited generator in China and the possibility of its application in the aircraft power system.Firstly, the structure and the fundamental principle and performance characteristic of HESG are discussed in this paper. The mathematical model of HESG is presented afterwards. The voltage characteristic of the permanent magnet synchronous generator is fully discussed and the rule of the influence of the performance and the structure parameters on the voltage characteristic is quantificationally analyzed. In this paper the problem has been solved to make the inherent voltage regulation quantificationally controllable in the generator design. A method has also been found to reduce the inherent voltage regulation and a prototype generator has been made. The comparison between the calculations and the tests of two prototype HESGs showed that the mathematical model in this paper is reliable as well as practical.A new method, with a relevant program written in an advanced program language MATLAB, has been brought forward and used in the design and calculation of the HESG mentioned in this paper. The method is showed reliable with the test verification of the prototype HESG and the method is also adequate for the design of a rare earth permanent magnet synchronous generator.With the reliable mathematical model and through the example calculation of some generators, the comparison of the HESG with the rotating rectifier brushless generator has been made to analyze the prospects of the HESG used in aircraft power system. The conclusion is that the kind of HESG has obvious advantages in the aspect of efficiency and reliability in the Constant Speedand Constant Frequency (CSCF) aircraft power system. However, its volume is bigger than the rotating rectifier brushless generator if the overload factor is considered. This kind of HESG is unable to realise the voltage regulation in the Variable Speed and Constant Frequency (VSCF) aircraft power system. Meanwhile, The characteristics of Permanent magnet material is also the main factor to obstruct the application of the HESG in aircraft power system.