Design And Research On The New Type Of Magnetic Field Modulated Integrated Motor Used In Oil Pumping Units

In order to obtain the characteristic of low-speed large-torque output in the industrial production,the motor and gear reduction mechanism are generally used in driving system of oil pumping unit,and it will not only increase the size and weight of the entire system greatly,but also accompanied by the problem of noise and the reduction of efficiency.As to the traditional low-speed high-torque permanent magnet motor,the leakage of magnetic flux will be large and the output torque of the motor will be lost because of too many pole pairs numbers.In addition,in order to achieve low-speed and high-torque drive,the volume of permanent magnet synchronous motor is generally massive.The large motor load current increases the cost of control circuit components and its torque density cannot meet the growing demand.In the past two years,the new inventions,new technologies and new structures have been coming out one after the other in the field of new energy applications.The new type of concentric magnetic gears has provided a new way for the development of high torque density motors.Magnetic-geared-integrated motor is the new motor which combined the permanent magnet gear topology and conventional permanent magnet motor based on the principle of magnetic field modulation.The new motor combines lots of the advantages of the traditional permanent magnet motor and permanent magnet gear,compared with the driving system of traditional mechanical gear,the compact motor will take a place in industrial production with the advantages of high output torque density and no need of the deceleration device,therefore,the research and development of the magnetic-geared and its compact motor have practical significance both for the theoretical research or production.According to the structure and working principle of compact electrical machine which derived from magnetic field modulation magnetic gear,the related literature at home and abroad was collected and summarized,and the general development situation was systematically introduced in recent years.Based on the working condition of pumping motor oil field,a new type low speed high torque of magnetic field modulation gear combined with permanent magnet motor was proposed and carried out the relevant research work,and specific content as follows:First of all,the characteristics of magnetic field modulation permanent magnetic gear mechanism was introduced and its magnetic field modulation principle through the analytic method was deduced to establish the mathematical model,low speed and high torque motor is proposed on the basis of this new structure and structure parameters is presented.Thedistribution of the air-gap magnetic field was calculated to verify working principle of the compact magnetic field modulation motor combined with finite element method,and the rationality of the structure was proved.The cogging torque and emf were researched by choosing different driving part,through the comparative analysis of two kinds of operation mode calculation results,the low speed high torque characteristics of this motor was proved.Secondly,according to the requirements of different working conditions,the best solution is chosen,and the original motor structure is optimized.The effect including the ratio K of the permeability section in the modulation ring and pole arc angle on the motor performance was researched specifically,and the main influence of the torque characteristics,and the prototype scheme of the Magnetic-Geared-Integrated machine was determined.The optimized motor both in the magnetic field distribution and its performance is superior to the basic design of the motor.Finally,the new concept of Magnetic-Geared-Integrated machine temperature field is calculated and analyzed,and the equivalent processing method is used to simplify and establish the calculation model of the temperature field on the premise of almost not affecting calculation results.The assumptions and the boundary conditions are given.The cooling system employs a fully closed and fan cooled system of induction motors,and various loss data obtained by electromagnetic field calculation are applied to the temperature field calculation program of the motor as a heat source.The temperature distribution in the steady state of the motor under the load condition is obtained by mesh and post-processing.The calculation results show the validity of the motor design.