Research On The Design Of Large Capacity Low Speed Permanent Magnet Wind Generator

This research content is funded by the State 863 Program named"Design andManufacture Technology for Novel Variable Speed Constant Voltage Permanent MagnetWind Generator"and cooperation program with Harbin institute of large electricalmachinery named"Design of 1.5MW Semi-Direct Drive Permanent Magnet WindGenerator". This dissertation is devoted to study the issues of cost, weight and generatingperformance which currently exist in the design and manufacture process of large powerlow speed permanent magnet wind generator (PMWG), and to establish and improve acomplete set of techniques on the basis of the development of two prototypes. The specificwork can be divided into the five parts as following:Firstly, the design criteria is presented for PMWG with PWM converter (Reduce theamount of effective material and cost). On the basis of studying the characteristics ofPWM rectifier system, a design criteria for PMWG with PWM rectifier is proposed. Theimpact of different parameters as synchronous reactance and no-load EMF on this designcriteria is studied. Furthermore, CAD software of PMWG with different rectifier systems isproposed.Secondly, the inductance parameter of low speed PMWG with fractional slotconcentrated winding (FSCW) is studied (Improve efficiency and fault tolerant capacity).FSCW is introduced into large capacity low speed PMWG in this thesis to improve thefault tolerant capacity. At first, winding function method is used to analyze the inductancequantitatively. Then, the saliency ratio of permanent magnet machine with FSCW issummarized by using finite element method. At last, a modular structure of both stator androtor for FSCW PMWG is proposed.Thirdly, thermal management technology for large capacity low speed PMWG isinvestigated (Improve the cooling performance). Through comparative analysis of differentcooling system, a single closed-loop axial ventilation system is proposed for large capacitylow speed PMWG. This cooling system is applied to a 1.5MW semi-direct drive PMWGby using the calculation tool of flow field and temperature field. Some key factors that may have a great influence on thermal analysis are considered. At last, the experiment carriedout on the 1.5MW prototype validates the feasibility of the cooling system and thecalculation accuracy.Fourthly, structural analysis and weight reduction design technology for largecapacity low speed PMWG are developed (Weight reduction). At first, on the basis ofsuperposition and continuity theory of elasticity mechanics, an analytical model isestablished for deformation calculation of a disc rotor support under radial electromagneticforce. Then, a modified disc structure with radial reinforcing plate distributed uniformlyalong the circumferential direction is proposed to improve the stiffness of the rotor. Thestiffness and weight of rotor under different amount and thickness of reinforcing plates areanalyzed. Finite element optimizing software is used to optimize the rotor structure toachieve weight reduction goal. At last, the modified disc structure is applied to twoprototypes to verify the feasibility of this structure.Lastly, by making use of the previous research results, a 100kW PMWG prototypewith FSCW, quasi-closed slot, stator and rotor modular structure and a 1.5MW PMWGprototype with single closed-loop axial ventilation system and disc structure are developedto verify the previous research contents. Through the comprehensive testing of theprototypes, the results verify the key technologies proposed in this thesis.