Research Of Permanent Magnet Synchronous Motor For Gearless Oil Drilling Mud Pump

Mud pump is an important component of oil drilling equipments. Mud pump transports flush fluid like mud or water into bore in order to cool drill, to carry debris and to protect wall. The development of modern petroleum drilling technique requires higher and higher performance gearless mud pump. Therefore, research on low speed and high torque PMSM used for driving mud pump crankshaft directly and canceling reducer makes sense. This thesis had intensive research on the design method of PMSM used in gearless mud pump and obtained some results of engineering application value.This thesis includes the following four parts:Firstly, original structure of mud pump is improved. PMSM directly drives crankshaft, realizing gearless transmission. Vector control system is designed which is made up of high performance inverter and incremental encoder. Meanwhile, relay electrical control assists in the vector control system. All these were designed to accurately control mud pump system.Secondly, design requirements and parameters of PMSM are provided, the method of designing gearless mud pump is researched. Main design parameters are discussed such as electromagnetic load, flux density, air gap length, stator and rotor dimension and permanent magnet size, etc. Rotor adopts surface permanent magnet structure. As for supply voltage and rated voltage not matching problem in drilling spot, a method of wide voltage with tapped winding is brought. This method is verified practical and feasible in oil field scene.Thirdly, according to basic design theory of PMSM, mud pump load, working environment and structure feature, a PMSM used in gearless mud pump is designed in electromagnetic aspect. Electromagnetic software of PMSM used in mud pump with Matlab is programmed and debugged. Meanwhile, finite element analysis software is used for obtaining simulation waveform of air gap flux density, magnetic field distribution and no-load back electromotive force.Finally, on the basis of the research above, a 15kW and 80r/min PMSM prototype used in varying frequency starting mud pump is designed. The performance test on prototype in no-load and load occasion is carried out. The efficiency is 12.4% higher than induction motor. Overload capacity increases to 2.2 times than original induction motor. Test results show the performances of prototype meet design requirements and verify the correctness of the design method on PMSM used in gearless mud pump.