Research On Permanent Magnet Motor For Oil And Gas Field Cementing Machine

Cementing work is to use cement slurry to fix the casing.The main purpose is to strengthen the well wall to prevent collapse.During the cementing work,the pressure in the well will vary with the work process.Therefore,the cementing equipment needs a wide output pressure range,and the output pressure of the cementing equipment is inversely proportional to its rotational speed,that is,the output pressure is small when the cementing equipment rotational speed is large,so it is in the low rotational speed and high rotational speed most of the time during the cementing work.pressure conditions.At present,the cementing equipment adopts the driving method of diesel engine and reducer.This driving method has problems such as cumbersome maintenance work,high operating noise,and excessive equipment volume and weight.In order to solve the existing problems.This paper designs a permanent magnet motor for cementing equipments with a rated speed of 500r/min and a peak speed of1500r/min according to the characteristics of cementing work.Research on energy and electromagnetic vibration.First of all,when the permanent magnet motor for cementing equipment runs below the rated speed,it is controlled by constant torque.It is constant power control when the speed is above the rated speed.In order to cementing machine can better use the permanent magnet motor,the pole slot fit,air gap length and magnetic steel size of permanent magnet motors used in cementing equipment are designed in this paper.On this basis,three different rotor structures of V-rotor structure,(?)-rotor structure and double-layer V-rotor structure are designed.And the differences in the field weakening rate,salient pole rate,air gap flux density and cogging torque of motors with different rotor structures are compared.And choose a Vrotor structure that is more balanced in torque performance and field weakening performance.Secondly,in order to make the permanent magnet motor for cementing equipment have a larger magnification factor of weak field expansion.The V-rotor structure is designed by orthogonal experiment.In this paper,five dimensions of V-shaped rotor structure are selected as variables.Namely the thickness of the rotor yoke,the steel magnetic included angle,the width of the magnetic steel isolation bridge of the same pole,the length and width of the nonhomopolar magnetic steel isolation bridge.Use finite element simulations to model combinations of variables in orthogonal matrices,in order to improve the flux weakening rate and salient pole rate of the permanent magnet motor for cementing machine,the values of each variable are determined,and the rotor topology structure meeting the requirements of the rotating speed range of cementing machine is obtained.Compared with the V rotor structure motor,the rationality of the rotor design is verified.The performance of the permanent magnet motor is verified by the prototype experiment.Finally,salient pole effect of the built-in rotor structure will cause the armature reaction harmonics,which may cause serious resonance phenomenon.In order to improve the stability of permanent magnet motor for cementing machine,the electromagnetic vibration of permanent magnet motor is studied in this paper.Through the theoretical analysis and simulation of the electromagnetic force,the spatial distribution and spectral distribution of the electromagnetic force are obtained.And its natural frequency is obtained by modal analysis.Based on this,the motor harmonic response analysis is carried out.It can be found that the lower the electromagnetic force order,the greater the influence on the resonance of the motor.In order to avoid serious resonance phenomenon when the permanent magnet motor is running,the natural frequency of the motor can be increased when designing the motor casing and end cover.