Research And Design Of The Speed Feedback Control System Of Linear Motor Pumping Unit

The pumping unit is an important implement for land oil filed. With the development of the techniques of oil extraction and the requirements of practical field production, the pumping unit has become more and more economical, intelligent, large-loaded and long-stroke. The Linear motor pumping unit is a new-style and efficient example emerging at the end of the 20th century.The linear motor pumping unit is driven by permanent magnet synchronous linear motor. When the load fluctuates largely, not only does it run unsteadily, but also it breaks down more frequently comparing with the traditional pumping units.Firstly aiming at the problems above, the techniques of oil extraction and the characteristics of the permanent magnet synchronous linear motor are studied, the mechanics model of the motor is given and the speed feedback control system is proposed. Then the hardware and software of the system are designed under the running circumstance of the pumping unit. The hardware of the control system consists of MM440 common transducer, S7-300PLC, rotary encoder and so on. The speed of the linear motor is inspected by the PLC and the output pulse of the rotary encoder. The change of the motor speed reflects the change of the load putting on the oil extraction rod. The output voltage of the transducer is adjusted according to the fluctuating load, then the thrust of the linear motor is controlled, which makes the linear motor pumping unit can respond to the fluctuating load putting on oil extraction rod. The response problem of the linear motor pumping unit to the fluctuating load is solved.Finally, the linear motor pumping unit has been tested both at the factory and in the field. The experimental results have proved that the control project is feasible and effective. The Linear motor pumping unit can steadily run in a large load fluctuating environment. The research results have laid the technical foundation for the spreading and application of the linear motor pumping unit, which is applicable.