Design And Research Of Brushless DC Motor And Its Control System Used In Direct-drive Screw Pump

With depth of oil field exploit, the energy saving problem of the pumpingunit has received extensive attention. The ground-drive screw pump oilproduction method is honored more and more, application prospect is very wide.But the traditional screw pump rig drive system generally uses asynchronousmotor with corresponding gearbox, has low efficiency, and difficult to regulatespeed, need to maintenance always. To solve these problems, this paper designsthe permanent magnet brushless dc motor and its control system directly drivescrew pump operation, saves the middle transmission device, increases thetransmission efficiency, also with the brushless dc motor some advantages, forexample, big torque, high efficiency, wide range of speed regulation, simplecontrol system etc.First, the brushless dc motor basic structure and working principle areintroduced in this paper. According to the design characteristics of brushless dcmotor and its control system used in direct driving screw pump, using the methodof combining the magnetic circuit calculation and finite element calculationfinish the design of the drive motor ontology. Results of motor steady-stateoperation and considering the starting up process of mechanical transient case offinite element simulation are analyzed. Using mathematical model of brushlessdc motor, based on Matlab/Simulink platform, the direct-driving screw pumpbrushless dc motor with current and speed double closed loop control systemsimulation model is set up, simulation waveform is obtained, provides the basisfor the design and develop of system. With high-performance digital processor TM320F2812as the core, thecontrol system hardware circuit of brushless dc motor used in direct drivingscrew pump is designed, include DSP control circuit, main circuit, driving circuit,testing and protection circuit. The scheme selection of each part of the circuit andcomplete function is expounded. Using C language primarily, to design thesoftware program of control system, including the overall program and interruptsubroutine. The flow diagram which is drawn based on the modular structuredesign thought is given. Finally, the design of brushless dc motor control systemis experimented and tested, the results show that system operation is stable andreliable, test results conform to simulation results, further verify the correctnessand rationality of design.