Research On Thermal Problems Of Deepwater Permanent Magnet Motors

With the continuous development of marine industry,deep-sea equipment research and development are rapid and underwater motors have become more widely used.Unlike conventional motors,underwater motors are affected by their special working environment and operating requirements.They have some problems like large losses,poor heat dissipation conditions and the problem of excessive local temperature of the motor.Therefore in this paper,a detailed study of the flow-thermal coupling field of deep-water permanent magnet motors and the establishment of an equivalent thermal network model of underwater motors from the perspective of industrial applications in view of the above-mentioned problems.First for the three-dimensional fluid model of the deep-water permanent magnet synchronous motor,the flow characteristics of the air gap fluid under different flow conditions are compared and analyzed.The radial,tangential and axial velocity components of the air gap fluid are extracted,and the influence of different external temperatures,pressures and properties of different fluid media on the flow state of the air gap fluid are analyzed respectively.Since the end of the motor winding adopts the overlapping winding connection method,the air gap fluid movement state at the end is complicated and the air gap fluid field at the end of the motor needs to be simulated and analyzed.Calculate the fluid friction loss of the air gap fluid,and analyze the influencing factors of the fluid friction loss.Finally because of the deviation analysis between the calculation results about the equivalent thermal network method and the finite element,the convection heat dissipation coefficient of the air gap in the finite element calculation results is extracted.The influence about environment temperature,pressure and motor speed factors on the air gap convection heat dissipation coefficient is analyzed.Therefore the correlation formula of the convection heat dissipation coefficient on the rotor surface is derived and the equivalent thermal network method is made corrections and verified their effectiveness.