Design Of A Linear Magnetic-geared Permanent Magnet Generator For Stirling Power System

Solar power generation as an important form of solar energy development and utilization, mainly including two types of photovoltaic(PV) power generation and solar thermal power generation. The PV power generation has been mature, compare with the solar thermal power generation technology is still in the stage of research and primary demonstration. At present, the National Development and Reform Commission has take solar thermal power generation as the important direction of new energy category.Especially, the stirling power generation technology, has become a hot research topic, while as the highest photoelectric conversion efficiency of solar thermal power generation technology. In the dish stirling power generation system, generator as an important device of energy converting between mechanical and electrical, it has critical influence on photoelectric conversion efficiency and power quality. According to the characteristics of low speed, low power density and low material utilization rate, a linear magnetic-geared permanent magnet generator(LMPMG or composite generator) for stirling power generator system is proposed in this thesis.And theoretical analysis, electromagnetic design, parameter optimization,dynamic performance optimization design and prototype fabrication are carried out. Main research contents of this thesis are as follows:Firstly, the LMPMG is proposed in this thesis, which consists of linear generator and linear magnetic gear-the two are tubular structure, and are in the form of parallel coaxial integration-with dual mechanical ports and three layers of air gap. Based on the analysis of the operation principle of composite generator, this thesis emphatically introduces the electromagnetic design process of the composite generator from the aspects of material selection, main dimension determination, stator winding design and electromagnetic load selection. So, the structure and main dimensions of the composite generator in this thesis are determined, and analysis of the winding factor by using the back electromotive force(EMF) vector diagram.Secondly, the finite element analysis of the LMPMG is carried out by using the electromagnetic field analysis software Ansoft, put forward thecomposite magnetizing method for the permanent magnet of the mover(Halbach magnetization and radial magnetization combination), for improving the back EMF fundamental amplitude and reduce the harmonic content effectively. The static performance of the composite generator is analyzed in detail in this thesis, including no-load magnetic field, back EMF and thrust characteristic. At the same time, in order to obtain the reasonable structure size and reduce detent force, the structure size and detent force of composite generator are optimized respectively. On the basis of this, the inductance, efficiency and load characteristics of the composite generator are calculated.Finally, this thesis has optimized the dynamic performance of the LMPMG and machined prototype. However, compared with the traditional generator, its stiffness is low, due to the composite generator carry out electromagnetic coupling through magnetic gear, which will lead to the transient oscillations undergoing the thrust of prime motor is disturbance or the velocity changes. In this thesis, a design scheme of composite generator with damping winding is presented, in the iron core of high speed mover of composite generator introduces damping winding with closed loop, in the process of transient oscillations, current will be induced in the damping winding, which will produce damping electromagnetic thrust, can inhibit the mechanical vibration of transmission shaft and maintain the stability of power system. Finally, the test data of the prototype is in agreement with the theoretical calculation, which shows the correctness of the LMPMG.