Well Detection Pump Steady-Speed Driving System of Brushless DC Motor
|School||Harbin Institute of Technology|
|Course||Power Electronics and Power Drives|
|Keywords||Well detection BLDCM driver PLL steady-speed control speed analyst|
With oilfield development processing to reservoir and its high temperature, requirement with oil detection pump’s operation performance and accountability should be met in oil production. Oil detection pump Brushless DC Motor is more popular in oil production, with the advances of high efficiency energy saving, good speed regulation performance and easy control style. Magnetic field of BLDCM at different temperature is calculated, factors that give influence on speed of BLDCM are analyzed,and a steady-speed control system of BLDCM is studied in this paper.A magnetic field analysis model of BLDCM is set with finite element analysis software, through the simulation,BLDCM’s field distribution and air flux are calculated. According to the characteristics of high temperature in oil well detecting, four factors are analyzed in this thesis: load, air gap flux, winding resistance and drain to source voltage of power devices; the trend of speed vs temperature are given under no load or rating torque and testified with high temperature experiment.A steady-speed drive system of BLDCM is designed in this paper. Firstly, the drive circuit of BLDCM is designed: the hall component is selected as the position sensor, integrated power driving chip is used to drive the three-phase inverse circuit, and GAL is used to realize the function of logic control. The steady-speed circuit is designed based on PLL chip and MCU: speed digital setting is designed with integrated V/F chip, the feedback circuit is designed with speed sensor and doubling circuit, given speed signal and feedback signal are compared in the PLL chip to give out analog voltage to MCU’s A/D, which generates PWM pulses to control the speed. Based on MCU, the system’s software is designed with the following functional programs: main program, PWM generating, A/D subprogram, D/A subprogram and digital filter subprogram, which simplifies the hardware circuit. With the combination of hardware circuit and software, the control system can realize the functions of soft start, positive and negative rotation controlling, current limiting and close-loop speed adjusting.Several experiments with the system is carried out: full load experiment, power MOSFET shut-off experiment, soft starting experiment, BLDCM’s operating at high temperature experiment, and steady-speed experiment. Experiment results show that the system can realize all the functions designed, and have high stability and expecting speed precision that meets well detection’s requirement.