Loss Analysis And Structural Optimization Design For Interior High Efficiency Permanent Magnet Synchronous Motor

Facing the severe energy problem,China has higher and higher requirements for motor energy efficiency indicators,and the problem of improving motor energy utilization has become increasingly prominent.Due to the advantages of high power,high power density and wide efficiency range,permanent magnet synchronous motor has begun to replace asynchronous motor in some engineering fields.Among them,the interior permanent magnet synchronous motor has the characteristics of high mechanical strength,large space utilization in the rotor and significant salient pole effect,which can further improve the power density and efficiency of permanent magnet synchronous motor,so it’s favored by many motor designers.However,only using the finite element method makes the calculation result of iron loss inaccurate and affects the accuracy of efficiency calculation.At the same time,the treatment of motor performance constraints in the multi-objective optimization design of motor structure is not perfect.Therefore,it has great practical significance to study the iron loss and structure optimization method for the interior high-efficiency permanent magnet synchronous motor.Firstly,this thesis introduces the research status and existing problems of motor iron loss analysis and structural optimization design,obtains the initial structural design scheme of the target motor through theoretical calculation,discusses the influence of stator chute and control method on electromagnetic torque,power factor and torque fluctuation in motor design,and determines the best chute angle and motor control mode.Secondly,by analyzing the magnetic field characteristics of the motor stator under the rated load,the iron loss calculation model is simplified on the premise of considering the harmonic of the magnetic flux density of the silicon steel sheet,which lays a foundation for the accurate calculation of the motor efficiency.Then,the appropriate motor structure design variables are selected,and the design constraints are determined according to the technical indexes with the goal of efficiency and the use of permanent magnets.In the optimization process,in order to reduce the amount of calculation of finite element and iron consumption model,Kriging based model is adopted and its prediction accuracy is evaluated.At the same time,in order to solve the problem of dealing with the constraints such as line voltage and torque fluctuation required in the actual motor design,the particle swarm optimization algorithm is improved.By introducing the way of "screening" and "proliferation",the constrained problem is transformed into unconstrained problem,which enhances the universality of the algorithm.According to the improved particle swarm optimization algorithm,the Pareto front of the multi-objective function is obtained,and the relatively ideal structural parameters are selected.Through the comparison before and after optimization,the motor efficiency is improved and cost is saved.Finally,the overload capacity,core loss,rated efficiency,temperature rise and other performance of the machined prototype were tested by the built test platform.The experimental results prove the effectiveness of the iron loss calculation model and the structural optimization design method,and provide reference value for the efficiency calculation and structural optimization of this kind of motor.