Research On Sensorless Control Of Permanent Magnet Synchronous Submersible Pump Motors

In respond to support the call of national energy saving and pollution reduction,it is necessary to increase the capacity of oil exploitation and reduce the energy consumption of equipment.Permanent magnet synchronous motors of submersible pump have many advantage,such as small volume,high efficiency and strong ability of overload.It not only improves the efficiency of oil production,but also reduces mining cost.In addition,the position sensor of a motor can not be installed because of the special working environment.Therefore,the sensorless control of permanent magnet synchronous motors of submersible pump was studied in this paper.Firstly,the transmission process of PWM voltage pulse on a power cable has been described.Then the influence of PWM voltage pulse rise time on the overvoltage of submersible motor is studied.The domestic and foreign solution to the existing problem was comparised.The modulation strategy of multi-level inverter can improve the output quality of inverter and depress overvoltage and resonance of a submersible motor.Secondly,the sensorless control principle of permanent magnet synchronous motor based on traditional rotating high frequency voltage injection method has been introduced.Aimed at solving the problem of rotor position estimation using heterodyne method,a novel rotor position demodulation method based on all pass filter was studied.A vector control model of permanent magnet synchronous motor was built,which was based on traditional rotating high frequency voltage injection method.The simulation result shows that the method can solve the existing problems of the rotor position estimation delay and improve the accuracy of rotor position estimation.Thirdly,the traditional sliding mode observer has been improved through the choice of switching function,the selection of sliding mode gain coefficient,the rotor position extraction and etc.A vector control model of permanent magnet synchronous motor was built,which was based on the improved sliding mode observer.The simulation result shows that the proposed method can solve the chattering and time delay of the traditional sliding mode observer effectively.In order to solve the sensorless control problem of permanent magnet synchronous motors of submersible pump at full speed range,a weighted switchingstrategy with variable weights has been adopted.And the proposed strategy realizes the smooth switching between the two sensorless control methods in different speed ranges.A vector control simulation model of the compound control based on two sensorless control methods was built.Then the feasibility of the method was verified through the proposed model theoretically.Finally,the hardware and software of the DSP+FPGA control system were designed,which were based on the characteristics of the variable frequency drive system of the submersible pump.It will create a condition for the subsequent experimental verification.