Design And Optimization Of Dual Permanent Magnet Excited Vernier Motor For Direct Driving Beam Pumping Unit

The direct driving beam pumping unit with permanent magnet integrated motor as the power source has the advantages of high efficiency,low noise,maintenance free,zero pollution and long life,but has problems such as complex structure and processing difficulties.The traditional Permanent Magnet Vernier Machine(PMVM)is relatively simple in structure and production process,but the magnetic load is severely restricted,it is difficult to further increase the torque density.The proposed Dual Permanent Magnet Excited Vernier(DPMEV)motor with permanent magnets in both the stator and rotor offers an opportunity to solve this problem,based on the bi-directional magnetic field modulation theory,which can effectively increase the magnetic load of the motor and improve the torque density.In this thesis,the DPMEV motor is introduced into a direct driving beam pumping system and its working principle,design,optimization and temperature field analysis are systematically investigated.The main research elements are as follows:Firstly,the working principle and operating properties of the DPMEV motor are analyzed.To solve the problem that the magnetic load of PMVM is limited,the DPMEV motor topology is established based on the bi-directional magnetic field modulation theory;the theoretical connection between the two motors is derived,and the finite element analysis shows that the electromagnetic torque of the DPMEV motor is 40.2%higher than that of PMVM under the same volume of permanent magnets.Secondly,a DPMEV motor for a 24 k W direct driving beam pumping unit was designed.Based on the derivation of the main dimensional equations of the DPMEV motor by the magnetic circuit method,the minimum value of the DPMEV motor cogging torque can be obtained when the rotor permanent magnet pole arc coefficient is 0.583 and the stator permanent magnet pole arc coefficient is 0.727 through the combination analysis of the pole arc coefficients.And single reference optimization of the DPMEV motor stator and rotor parameters was carried out to determine the main motor parameters.Then,the optimization method of the DPMEV motor is investigated.An orthogonal particle swarm optimization method is proposed for the DPMEV motor to address the problems of time consuming,slow convergence and low efficiency of the multi-objective particle swarm optimization method.The finite element analysis results show that the number of simulations can be reduced by 45% and the volume of permanent magnets can be reduced by 7.7% compared to the multi-objective particle swarm optimization method,while ensuring the electromagnetic output requirements.Finally,the optimized DPMEV motor is subjected to temperature field simulation and permanent magnet demagnetization analysis.For the problem of irreversible demagnetization of permanent magnets due to the increase of motor temperature,the highest temperature of the motor is 112.5 ℃ at the rotor position by using finite element simulation analysis,which determines the Nd Fe B grade as N30 H,and the demagnetization of permanent magnets is verified by considering the demagnetization current and temperature demagnetization.The above work provided new ideas for the design and optimization method of DPMEV motor,and provided some reference significance for its application research in the beam pumping system.