Studies On Wide Constant Power Variable Frequency Asynchronous Motor Of Workover Rig

The workover rig is a necessary device to maintain and ensure mining technics in the oil field, and its main application is to elevate or drop oil pipes and pumps. However, most workover rigs are driven by the diesel engine, inevitably with low efficiency and high pollution. Therefore, the development of drive system of traditional workover rigs in accordance with national policies favors for the enterprise and society benefits.The wide constant power variable frequency induction motor of workover rigs combine the advantages of variable frequency with variable poles. Using a single set of winding, the range of constant power rise one time as before, without increasing the supply frequency. When the diesel engine is replaced with asynchronous motor, the disadvantages of wokover rig drived by diesel engine are overcomed all. Therefore, the development of wide constant power variable frequency asynchronous motor of workover rig for oil field has become one of the currently significant tasks.Firstly, in this paper, the range of constant power of induction motor is studied, moreover the relation between capacity of inverter with parameters of the motor. The reasonable cooperate capacity between inverter and motor can be obtained by adjusting parametres of induction motors. Secondly, according to the load characteristic of well and the quest of drive system, the parameters of the workover rig and drive system project is calculated. Later, based on the design theory of variable frequency induction motor and single winding double speed induction motor, the wide constant power variable frequency induction motor of workover rig is designed. After removing the deceleration machine, the number of stator slots is 72. In low speed and heavy load situation, the stator winding is delta, rated power is 90kW, with 12 poles, range of supply frequency is from 25 to 50Hz, and the responding speed is from 250 to 500r/min; In high speed and light load situation, the stator winding is star, rated power is 110kW, with 6 poles, range of supply frequency is from 25 to 85Hz, and the responding speed is from 500 to 1700r/min. Used Ansoft, magnetic field distribution and performance simulation are done on the rated and limit working situation, obtain the air-gap flux denesity, torque, speed curve and so on.As prototype, Some on-site experimentation had been done. Experiment data approve that the prototype has high performance, and its working range increase one time as before. The operation time of single pipe cut down from 47.7s to 30s. Per kilometers cost price decrease from 3000 yuan to 300 yuan, so it has remarkable energy-saving efficiency. The research work in this paper is very important to improve the design method of wide constant power variable frequency asynchronous motor of Workover rig used in Oil Field.