Design And Optimization Of Solar Stirling Linear Permanent Magnet Vernier Generator

Solar Stirling power systems are widely used in solar energy applications and heat recovery due to their wide fuel source,low pollution and high efficiency.The Stirling linear generator set used in this system consists of a Stirling engine and a linear generator,which completes the conversion from thermal energy to electrical energy.At present,the linear generator used for this unit has shortcomings such as low thrust,low power density,and low thermoelectric conversion efficiency.To solve this problem,a small Magnetic Barrier Linear Permanent Magnet Vernier Generator(MBLPMVG)has been designed by introducing a linear permanent magnet vernier generator into the Stirling linear generator set.The topological structure,electromagnetic performance,parameter optimization,and temperature field distribution of MBLPMVG are systematically studied.The main research contents are as follows:Firstly,the topology and magnetic field modulation mechanism of the MBLPMVG are investigated.Aiming at the problems of magnetic leakage and large losses in existing linear permanent magnet vernier generators,a magnetic barrier structure is proposed,which can reduce eddy current losses and improve the magnetic field modulation ability of the motor.The magnetic field modulation mechanism of MBLPMVG is theoretically derived,and the equivalence magnetic circuit method is used to analyze the magnetic field variation pattern of the MBLPMVG.Comparing two types of motors with different secondary structures,the results show that MBLPMVG has better motor performance.Secondly,the initial values of the main parameters of MBLPMVG are determined.at the same time,the electromagnetic analysis is carried out.Theoretical derivation of the equations for the main parameters of the MBLPMVG is carried out,the effect of the main parameters on the performance of the generator is investigated using finite element analysis,and the dimensional parameters of the MBLPMVG are initially determined.Considering that the permanent magnet material may produce demagnetization problem when the generator is running,the advantages and disadvantages of different permanent magnet materials are compared and appropriate permanent magnet materials are selected.After determining the size parameters of MBLPMVG,the influence of generator parameters on thrust,no-load back electromotive force,and permanent magnet flux linkage is analyzed,laying the foundation for multi-objective optimization of MBLPMVG.Then,in order to improve material utilization and generator performance,multi-objective optimization is carried out for MBLPMVG.Aiming at the problems of existing generator optimization methods such as single optimization objective,slow convergence speed and poor search ability,an optimization method combining Response Surface Methodology(RSM)and orthogonal method is proposed.The RSM orthogonal method is used for multiobjective optimization of the generator,and the optimal structural parameters of the generator are obtained through fewer tests.The analysis results show that this method improves generator performance,simplifies the complicated optimization processes,saves the optimization time,and provides a new idea for multi-objective optimization of generators.Finally,taking into consideration the influence of temperature on the function of the generator,the temperature field of the generator is analyzed.For the sake of assure the stability of the generator operation,the various losses of MBLPMVG are analyzed.The calculation of thermal conductivity and heat dissipation coefficient and boundary conditions are determined.According to the operation condition of the generator,simulating the temperature field of the generator,and the temperature distribution of each part of MBLPMVG are analyzed.The above work provides an effective way to improve the performance of Stirling linear generator and the thermoelectric conversion efficiency of solar thermal power generation system,and provides a strong reference for the promotion and application of linear permanent magnet vernier generators in this system.