Design And Optimization Of Permanent Magnet Brushless DC Slotless Motor For Missile

With its high power density,reliable and stable operation characteristics and other advantages,permanent magnet motors have become the main actuators in aerospace,weapons and equipment,industrial production and life.Guided missile is one of the modern military weapons,and the motor in the steering system is the key to give the missile guidance ability.With the rapid progress of various weapons and equipment technology,guided missiles are also developing in the direction of smaller volume,lighter weight and higher accuracy.Because there is no stator slot,the permanent magnet brushless DC slotless motor is smaller than the traditional motor with stator slot,which can play its role in the limited space of the missile body to achieve the purpose of increasing the missile range.In this paper,the design and optimization of permanent magnet brushless DC slotless motor for ammunition are studied.The thesis begins by introducing the fundamental structure and working principle of the permanent magnet brushless DC slotless motor,followed by an analysis of its mathematical model and steady-state operation performance.Additionally,the thesis discusses the design methodology of this type of motor,taking into consideration its unique characteristics,which includes the primary dimensions,permanent magnet size,and winding design.In order to adapt to the special working situation of missiles,a suitable motor material is selected by searching the properties of contrasting materials.The magnetic field model for a specific type of motor was established,allowing for the calculation of the air gap radial flux density formula.Using this formula,a permanent magnet brushless DC slotless motor,which is frequently used in missiles,was designed based on technical specifications and design methods.The motor’s size parameters were then analyzed under both no-load and load conditions using the three-dimensional finite element method to evaluate its working conditions.Then,by analyzing the special winding structure of the permanent magnet brushless DC slotless motor,this thesis explains the reason why the traditional rhombic winding can be improved,and establishes an equivalent two-dimensional optimization model of the single-turn rhombic winding,using the analytical method to convert the traditional The rhombic coil span of the slotless motor is optimally optimized.At the same time,combining the structural advantages of rectangular coils and rhombic coils,based on the mathematical model of optimizing rhombic coils,the optimal hexagonal winding structure scheme is obtained by using the analytical method to achieve the best performance of the motor.Moreover,based on the optimized winding scheme,the basic parameters of the motor are derived,and the optimized motor is analyzed using the three-dimensional finite element method under no-load conditions,load conditions,and power density comparison with traditional motors,and the correctness of the analytical formula is verified.The power density of the optimized motor is 12.68% higher than that before optimization.Finally,this study addresses the potential negative consequences of the permanent magnet brushless DC slotless motor’s high efficiency,such as permanent magnet loss,insulating material embrittlement,and damage to other components due to excessive temperature.To optimize the motor’s performance,the study analyzes the loss value,heat dissipation coefficient,and thermal conductivity data,and evaluates the temperature field.Through a combination of the three-dimensional finite element method and temperature field analysis,it is demonstrated that the optimized motor can operate normally for an extended period.This confirms the optimization scheme is reasonable and effective.