Research On Loss Calculation And Thermal Management System Optimization Of Water-cooled Permanent Magnet Motor For Compressor

As the core drive mechanism of compressors,permanent magnet motors are widely used because of their outstanding performance.Permanent magnet motors have high efficiency and simple structure.However,the power of permanent magnet motors for some compressors is often too large.The stator armature winding has high current density and serious heating,which affects the life and safe and reliable operation of the motor.Therefore,it is necessary to accurately calculate the temperature of the permanent magnet synchronous motor for the compressor.The ventilation and water cooling structure need to be designed reasonably so that the permanent magnet motor can still operate safely and stably when the armature winding is large current.A 560 k W compressor water-cooled permanent magnet synchronous motor is taken as an example.The two-dimensional electromagnetic field mathematical model of the permanent magnet motor is established.The air gap flux density and cogging torque of the permanent magnet motor are calculated.Based on the numerical analysis method,the copper loss,core loss and permanent magnets eddy current loss are calculated.According to the physical parameters of the permanent magnet motor structure,the heat density of the permanent magnet motor stator winding,permanent magnet and stator core are determined.Based on the slip grid method,a three-dimensional fluid-solid coupling solution model of a water-cooled permanent magnet motor considering the rotation of the rotor is established.Based on the Mosiac grid,the permanent magnet motor solution domain is discretized by the grid.Based on the fluid-solid coupling method,the global temperature field and fluid field of the permanent magnet motor under the turbulent state of the cooling medium are numerically calculated.The temperature and fluid distribution laws of the permanent magnet motor in the whole space are revealed.For the end windings of the permanent magnet motor with the highest temperature,the temperature distribution of the end windings on the fan side and the non-fan side and the fluid distribution in the end domain are compared and analyzed.Further,the temperature distribution of the permanent magnet motor windings and the flow velocity distribution of the cooling medium under different inlet wind speeds are studied.The permanent magnet motor air cooling system has been further improved.The three-dimensional fluid-solid coupling solution model of the dual-pass ventilation of the permanent magnet motor for the compressor is established and solved.The temperature and cooling medium flow rate distribution law of each structural part of the permanent magnet motor at different inlet wind speeds are obtained.The temperature distributions of the end windings in single and dual ventilation modes are compared and analyzed.The results show that the dual-pass ventilation mode effectively reduces the temperature of the hottest spot of the end winding.In order to verify the correctness of the fluid-solid coupling heat transfer three-dimensional model of permanent magnet motor,the prototype was designed,manufactured and processed.The permanent magnet motor temperature measurement platform was built.The temperature of the end windings is measured and compared with the calculated results.The problem of excessively high temperature of permanent magnet motors for high-power compressors is solved,which provides a theoretical reference for the heating and cooling design of permanent magnet synchronous motors for compressors.