Research On Direct Drive System Of Gas Station Submersible Electric Pump Permanent Magnet Motor

The traditional gas station adopts a self-priming pump type tanker with negative pressure refueling mode,whose structure determines that each tanker must be equipped with a self-priming pump and a pipeline resulting in complex structure and layout.Negative pressure refueling process will lead to the presence of oil and gas mixture in the pipeline,resulting in gas resistance problems,affecting the interests of customers.Many gas stations in foreign countries have adopted the same principle of positive pressure refueling as the online urban water supply system,which can improve the quality of oil delivery,improve the work efficiency and economic benefits of gas stations,and reduce the station construction cost and operation cost.The common positive pressure refueling method uses asynchronous motor which does not need special sealing design to drive the oil pump through the transmission rod.However,the existence of slender transmission rod increases the manufacturing cost and reduces the sealing performance of the oil tank.There is an explosion risk since the contact volatilization loss between gasoline and external air.A shielding sleeve is needed to add at the air gap of the Submersible asynchronous motor to eliminate the harm of gasoline to the stator winding and rotor guide bar of the motor,which will increase the air gap of the motor,increase the loss and reduce the efficiency of the system.In order to solve the above problems,a variable frequency speed submersible permanent magnet synchronous motor is designed in this paper,which is used to directly drive the submersible pump improving the operation efficiency and stability of the system.The main work of this paper is as follows:(1)Poles and slots combination with integer slots is often used in the design of submersible motor,and stator lamination is applied from asynchronous motor lamination.The electromagnetic design of permanent magnet synchronous motor for submersible pump is completed by field-circuit coupling method to reduce the loss caused by air gap harmonics in the shielding sleeve and improve the running performance of the motor.The design scheme of submersible permanent magnet motor is determined by comparing the simulation results of integer slot and fractional slot.For motors with fewer slots,the simulation results of magnetic density distribution of pear-shaped slot and trapezoidal slot are compared,and an appropriate scheme is selected to improve the power density of the stator,thereby improving the utilization rate of punching sheets,reducing the volume and weight of the motor and saving the cost of the motor.(2)For submersible permanent magnet motor,the structure and size design of the stator shield is completed in this paper to improve the tightness and heat dissipation of the motor.A closed stator cavity is designed between the stator shield and the casing,and the sealing design is completed by injecting epoxy resin.The thickness and material of the stator shielding sleeve are determined by calculating the loss of the stator shielding sleeve,and the effects of integer slots and fractional slots on the loss of the stator shielding sleeve are compared and analyzed.(3)The simulation model of the vector control system is built in this paper to improve the response speed of the motor and reduce the waiting time for refueling,so that the motor can run stably in three stages of acceleration,constant speed and deceleration according to the oil pressure in the pipeline.The simulation results prove that the control system can track the given speed well and has strong anti-disturbance capability.On the basis of the selection of inverter module,rectifier module and other components,the controller is designed inside the pump body through the hardware design and layout design,thus eliminating the heat dissipation system,shortening the distance between the controller and the motor,and improving the reliability of the system.