Electromagnetic And Thermal Anaysis Of Canned Permanent Magnet Synchronous Motor

Due to good sealing and high safety,canned pumps are often used in the fields of pharmacy,chemical industry,petroleum and nuclear,to transport corrosive and flammable liquids.Canned motor is the core component of canned pump,and the performance of canned motor determines the performance of canned pump.A pair of metal shielding sleeves are embedded in the airgap,causing the difference between the canned motor and the conventional motor.In alternating magnetic field,eddy current is occurred on the canned,here is called canned current.The canned current produces a magnetic field,affecting the original airgap magnetic field in return,here called electromagnetic shielding.Canned current brings loss,causing temperature rise.The change of motor temperature leads to the change of shielding sleeve electrical and thermal parameters,thereby affecting the canned current,here is called electrothermal coupling.The research object is the canned permanent magnet synchronous motor,with the goal of studying electromagnetic coupling and electrothermal coupling.Meanwhile,the electromagnetic analytical method,electromagnetic finite element method,heat transfer analytical method and heat transfer finite element method are studied in depth.For the electromagnetic analytical method,since the traditional analytical model cannot be directly applied to the canned permanent magnet synchronous motor and solve the problem of electromagnetic coupling,so a multi-layer concentric cylinder electromagnetic model is proposed,to build a multi-harmonic,strong coupling,multiparameter electromagnetic analytical model.On the premise of winding and permanent magnet magnetomotive force,using the separation variable method to solve the diffusion equation,using the Bessel equation to solve the Maxwell equations to obtain the magnetic field of the motor,thereby exploring the electromagnetic shielding.Electromagnetic analytical method can quickly and accurately calculate the electromagnetic characteristics of the motor,but it cannot effectively show the distribution of canned current and loss.For the electromagnetic finite element method(FE),to solve the problem that the electromagnetic analytical method cannot effectively display the field distribution,the FE model of canned permanent magnet synchronous is built.Using 2D FE to study electromagnetic shielding phenomenon and extend the conclusion of electromagnetic analytical method.Meanwhile considering the end effect,using 3D FE to show the distribution of canned current and loss under different conditions.For the heat transfer analytical method,due to the problem of low calculation accuracy of the traditional thermal network model,a thermal network model with compensation elements is proposed.The compensation element makes up for the deviation caused by the heat flow that is considered constant in the traditional thermal network.For canned permanent magnet synchronous motor,a new multi-node thermal network model is built.The thermal network model can quickly and accurately calculate the temperature rise of each component of the motor,but it cannot effectively display the temperature distribution of each component of the motor.For the heat transfer finite element method,in view of the problem that the heat transfer analytical method cannot effectively display the temperature distribution of each part of the motor,the heat transfer finite element method is proposed,to show the temperature of each part of the motor under steady state and perfect the heat transfer analysis of the motor.