Research On The Method Of Increasing The Ultimate Torque Capacity Of Permanent Magnet Servo Motors

In the fields of automotive power,military and robotics,permanent magnet synchronous motors have the problem of insufficient overload capacity at constant speed.Although the size of the motor can be increased to meet the output capacity requirements,it is contrary to the lightweight design requirements.Therefore,it is important to study the method of improving the ultimate torque output capacity of high overload motors under the conditions of both volume and mass constraints.Firstly,the electromagnetic parameters affecting the output performance of permanent magnet servo motors under extreme operating conditions are investigated.The influence of the stator teeth and stator yoke on the air gap magnetic density,the influence of the cross-axis armature response on the induced voltage and the variation pattern of losses under different operating conditions are investigated.The control mode and rotor structure of the motor are investigated with the objective of improving the ultimate torque output capability of the motor.In addition,the electromagnetic parameters affecting the ultimate torque output capability of the motor are investigated from the perspective of mathematical models.Secondly,the variation pattern of structural parameters on the ultimate output capability of permanent magnet servo motors is explored.The variation pattern of the motor’s ultimate torque output capability is investigated in five aspects: stator split ratio,slot width,air gap length,permanent magnet thickness and pole arc factor.The sensitivity of the five parameters to the ultimate torque output capability of the motor is analysed to find the three variables that have a greater influence on the torque output capability.A multi-objective optimisation of the motor is carried out using a genetic algorithm.Subsequently,the effectiveness of two rotor pole configurations,eccentric pole cutting with external pole arc and harmonic pole cutting,in improving the ultimate torque output capability of the permanent magnet servo motor is investigated.The Taguchi method is used to study the ultimate torque output capability improvement method from the perspective of rotor pole shaping.The effects of conventional tile pole,sinusoidal pole shaping and different harmonic pole shaping structures on the ultimate torque output capability of three-phase motors are analysed.A comparison is made between the effect of optimal external arc eccentric pole cutting and optimal harmonic pole cutting to improve the ultimate torque output and to design a motor with a high ultimate torque output.Finally,the internal temperature distribution of the better permanent magnet servo motor is investigated.Finite element solutions for copper,iron and eddy current losses are carried out,the thermal parameters of each component material are calculated using thermal principles,the windings are equivalently calculated and the model is simplified,and the temperature distribution and temperature rise of the designed motor under no-load,load and overload conditions are verified.