Control Research On Brushless Motor Direct-drive Pumping System

Owing to the problems of the traditional beam pumping unit system, such as long transmission chain, low system efficiency, big consumption of power and the control of the cost of crude oil in the mining process becoming more and more strict, all of the oil fields are trying their best to reduce the energy consumption of oil extraction, in order to reduce the cost of crude oil.In order to solve the above problems, the author puts forward the program of direct-drive pumping system which uses the outside rotor brushless DC motor as the driving source, on the basis of the analysis of the characteristics of the structure of the brushless DC motor and the condition of its service.The author designs the overall structure of the direct-drive pumping system on the basis of the original device structure, and discusses the principle of brushless motor direct-drive pumping system works. The following is the analysis about the law of the motion of the suspension point and the load changes of the direct-drive pumping system, from which we get the static indicator diagram and motion indictor diagram of brushless motor direct drive pumping system. Balancing system which uses the balance block as counterweight is designed according to the characteristics of the system structure. In addition, we determine the brushless DC motor control program, establish the mathematical model of the brushless DC motor, and make the simulation analysis about the control of the direct-drive pumping system. The control system which includes rectifier circuit, the steering control circuit, IGBT inverter, the steering control circuit and the auxiliary circuit so on, is designed on the basis of two core chips-integrated MC33035and closed loop speed control chip MC33039. The whole system has been tested by experiment, which has verified the feasibility of the control scheme.The theory analysis and the research intends that, the brushless DC motor direct-drive pumping system removes the intermediate transmission devices like gear reducer, four-bar linkage and so on, so that the drive chain is shortened, the system efficiency is improved, and the energy consumption is reduced. The system overcomes the disadvantages of the traditional beam pumping system and reduces the cost of the crude oil to some extent.