Design And Optimization Of Cylindrical Permanent Magnet Linear Motor With Low-speed And Large-thrust Fractional-slot Winding

The low-speed large-thrust fractional-slot winding cylindrical permanent magnet linear motor is a new type of motor suitable for special occasions such as oil fields.It can directly convert electrical energy into low-speed linear motion mechanical energy,and has wide application prospects.However,due to the low speed range of the conventional cylindrical linear motor,the thrust fluctuation is large at low speed operation,the running performance is extremely poor,and resonance occurs at the same time,which seriously affects the motor control performance.Therefore,there is an urgent need to improve the design and optimization of cylindrical linear motors to improve their operation and control performance in low speed and high thrust operating environments.In this paper,by analyzing the working principle and structural characteristics of the cylindrical permanent magnet linear motor,the fractional slot winding is used in the primary winding of the motor to achieve the purpose of speed reduction and increase the speed regulation range of the motor.The constraints of the distribution of the fractional slot winding are analyzed.According to the principle of maximum winding coefficient,the winding arrangement of the designed motor is determined.The motor design is determined by the selection of the main dimensions and the electromagnetic design.The 2D finite element simulation model of the cylindrical linear motor with fractional slot winding is established.The simulation of single-layer winding and double-layer winding motor under the same structure size is carried out.The simulation results show that the double-layer winding fractional cylinder running at different frequencies.The magnitude of the thrust,the percentage of thrust fluctuation and the efficiency of the permanent magnet linear motor are much better than those of the single-layer winding fractional cylindrical permanentmagnet linear motor.Therefore,the double-winding fractional-slot motor is ideal for low speed,high thrust and low fluctuation applications.The causes of thrust fluctuations are analyzed,and the cogging force and the edge force are weakened by the method of optimizing the pole arc coefficient and the primary length,respectively.At the same time,the edge tooth optimization method is used to weaken the thrust fluctuation of the motor,and the new optimization scheme is compared with the original scheme thrust fluctuation suppression characteristics.It is verified that the optimization scheme of the low-speed large-thrust fractional-slot winding cylindrical permanent magnet linear motor has a significant improvement in performance.The low-speed large-thrust fractional-slot winding cylindrical permanent magnet linear motor designed in this paper has the advantages of simple structure,large thrust amplitude,small thrust fluctuation,wide speed regulation range and high efficiency.It provides new design ideas and optimized design methods for cylindrical permanent magnet linear motors for low-speed and large-thrust applications.