Research On Solar Stirling Linear Magnetic-Geared Generator And Its Control System

Stirling solar thermal power generation system is widely concerned because of its simple working mode,safety and reliability.It has wide application prospect.However,due to structural constraints,the system has limited motive power.What results in low moving speed and low output power of Stirling Linear Permanent Magnet Generator,which is the system’s core component.In addition,linear generator has the disadvantages of low power density and low material utilization.These factors restrict further improvement of thermoelectric conversion efficiency of the system.Linear Magnetic-Geared Permanent Magnet Generator(LMGPMG)provides an opportunity to solve this problem.It has advantages of high power density,high material utilization,and can effectively improve driving speed of the system through its internal gear,which is very suitable for the systems with insufficient prime power.This dissertation focuses on design,optimization,analysis and control of LMGPMG.Main research results are summarized as follows:Firstly,topological structure of LMGPMG is researched.In view of the shortcomings in existing LMGPMG magnetic circuit coupling mode,such as serious interference among magnetic fields and difficult to manufacture,a series coupling structure is proposed,and determination method of its main structural parameters is discussed.The topology of LMGPMG directly determines coupling mode of magnetic circuit,and then affects its working characteristics.In order to reduce interference among magnetic fields,simplify topological structure and reduce manufacturing difficulty,series structure is proposed.It overcomes the inconvenient factors brought by guide angle in traditional series topological structure ingeniously,so that the secondary is not limited by guide angle,which has more practical application value.Design parameters of generator directly determine its performance index.LMGPMG is a new type of permanent magnet generator.The determination method of its main structural parameters is not perfect.Therefore,taking the proposed flat LMGPMG as an example,the determination method is discussed,what provides a necessary reference to LMGPMG’s structural design.Secondly,electromagnetic performance of LMGPMG are studied.The influence of magnetizing mode on electromagnetic performance of LMGPMG is studied by using finite element method,and electromagnetic performance of proposed LMGPMG is analyzed.Magnetizing mode of permanent magnet determines its magnetic field distribution,and then affects generator’s electromagnetic performance.In order to acquaintance the law of this effect,characteristics of magnetic field distribution of LMGPMG with different magnetizing mode is compared.The comparison results provide a basis for the choice of LMGPMG magnetizing mode.In order to further aware of spatial distribution and changing law with time of magnetic field in proposed LMGPMG’s,its electromagnetic properties,such as magnetic field distribution,no-load and load working characteristics,and power density are analyzed by using simplified two-dimensional model,what lays a foundation for development of LMGPMG.Thirdly,parameter optimization of LMGPMG is researched.Aiming at the defects of existing motor optimization methods,such as slow convergence speed,long time-consuming,low efficiency and difficult to achieve multi-objective optimization,a multi-objective orthogonal optimization method based on Response Surface Method is proposed,and the proposed LMGPMG is optimized by using the method.Optimization can further improve material’s utilization and generator’s performance.In order to simplify the calculation and improve optimize efficiency,the proposed multi-objective optimize method save optimize time by establishing mathematical model between multiple optimize objectives and structure parameters of LMGPMG,and realize multi-objective optimization by making use of the balanced distribution characteristic of orthogonal method and orthogonal analysis.Which can get satisfactory optimize results through fewer times experiment.It is simple and effective,and provides a new way for the realization of the multi-objective optimization.Then,the main structural parameters and laws they affect thrust characteristics,reverse electromotive force and detent force of proposed LMGPMG are studied.Based on above method and conclusion,the LMGPMG is optimized.What has important guiding significance for further study of LMGPMG.Fourthly,maximum power control method of LMGPMG is studied.In view of the disadvantages of traditional power control,such as unfixed switching frequency,poor immunity and time delay,a power control method based on Active Disturbance Rejection Control(ADRC)is proposed.The LMGPMG used in solar thermal power generation system is driven by Stirling engine.Its power control is complex.In order to ensure the maximum power operation,a maximum power control strategy considering power matching between LMGPMG and Stirling engine is proposed.LMGPMG power control is the core of the strategy.Compared with traditional linear generator,it is more difficult to control LMGPMG because of the increase of permanent magnet gear.For this reason,the direct power control method based on ADRC is proposed to solve the problems of existing power control system,such as unfixed switching frequency,poor anti-interference and time delay.The method makes switch frequency is fixed,response speed of the system is improved by using tracking differentiator,and anti-interference ability of the system is effectively improved with the aid of ADRC’s disturbance estimation and compensation function.Finally,in order to verify above design and methods,a plate-shaped series coupling structure LMGPMG is designed and discussed.The correctness and rationality about these methods are verified by necessary simulations and experiments.After that,LMGPMG’s principle prototype is made.Test results of the prototype further verify the design.Research results show that power density of LMGPMG is significantly higher than that of traditional linear generator.Its introduction can improve thermal power conversion efficiency of dish Stirling solar thermal power generation system effectively.Above work provides strong reference for further application of LMGPMG in this system.