Design Of Semi-Direct Drive Switched Reluctance Motor Drive System For Pumping Unit

The Switched Reluctance Motor(SRM)has the advantages of simple structure,high reliability,high starting torque,wide speed range and easy to realize four-quadrant operation,which is very suitable for driving oilfield pumping machines.However,conventional SRMs use belt drive in oil pumping machines,which often results to problems such as slippage,loss of rotation,and uneven force on the reduction gearbox.In addition,the torque pulsation during SRM operation is great,which often leads to mechanical damage to the bearings and rotor shaft.To address the problems,this paper designs an Axial Flux Switched Reluctance Motor(AFSRM),and adopts a semi-direct drive method in which the motor spindle is directly connected to the pumping gearbox drive shaft.The study shows that both AFSRM and this control strategy can effectively solve the existing problems.First,the thesis describes the research background and significance of the topic,and summarizes the current development status of AFSRM,torque pulsation suppression and speed control strategies at home and abroad.The mathematical model of AFSRM and the basic control strategy are explained.For the structure of the parallel stator slot and radial rotor pole of AFSRM,the method of solving the electromagnetic torque under the nonlinear model is highlighted,which provides a basis for determining the electromagnetic torque of the prototype.Secondly,the paper derives the relational equations of the main dimensions,the magnetization curves for un-aligned and aligned positions of the AFSRM,and determines the initial parameters of the AFSRM prototype based on the derived relational equations.Among them,the influence of the diameter ratio and aspect ratio on the torque between AFSRM and conventional SRM is illustrated to show the advantages of AFSRM made into a disk motor;for the flux of AFSRM is not symmetrical in both radial and axial directions,the quasi-3D analytical method is proposed to calculate the magnetization curves in the non-aligned position to simplify the problem;for the two-pole structure,the conventional magnetic circuit analysis method is applied to calculate the magnetization curves in the aligned position.In order to improve the motor performance,a multi-objective multi-parameter optimization design of the rotor poles is carried out by orthogonal experimental design and 3D finite element simulation,and the parameters of the prototype are finally determined.Based on the prototype,the simulation obtains the data of magnetic chain-angle-current and torque-angle-current,which provides data support for Simulink to build the motor model.Again,the thesis proposes a direct instantaneous torque control strategy based on fuzzy adaptive PID in order to suppress torque pulsation and improve the robustness of the control system.The simulation model of MATLAB/Simulink was established and simulated by combining the load characteristics and impulse regulation of the pumping machine.The simulation results are compared with those of voltage chopper control and conventional direct instantaneous torque control respectively,and the rationality and feasibility of the control strategy are illustrated.Finally,the hardware and software of the AFSRM control system are designed and written based on the DSP control chip TMS320F28335 to further verify the effectiveness of the AFSRM and control strategy designed in this paper.A prototype test platform is built and the motor performance such as starting torque and efficiency of AFSRM is tested.The experiments prove that the AFSRM drive system can be better adapted to the actual production needs,and the feasibility of the AFSRM drive system is further illustrated by the feedback data from the motor users.