Simulation And Calculation Of Multi-physical Field Coupling For High Power Ultra High-speed Permanent Magnet Synchronous Machine

High-speed permanent magnet machines have significant advantages such as high speed,high power density,small size and high efficiency,and are widely used in industry.The operation of a high-speed permanent magnet machine 1s a complex process involving multiple physical fields such as an electromagnetic field,a fluid field,a temperature field,and a stress field,and these physical fields interact and restrict each other.The reliability of high-speed permanent magnet machine operation is an important evaluation index for its normal operation.The reliability of the machine is mainly reflected in the temperature rise during operation.Therefore,the research on the loss,heat and cooling of high-speed permanent magnet machine appears.Increasingly important,the study of the coupling between electromagnetic fields,fluid fields and temperature fields is of great significance.Therefore,the special design and temperature rise research of high-power ultra high-speed permanent magnet machine has great academic and practical significance for the development of high-power ultra high-speed permanent magnet machine.Firstly,this paper takes 250kW,65000rpm high-speed permanent magnet machine as the research model,designs three kinds of rotor containment sleeve structure schemes,and in the presence of driving voltage harmonics,the eddy current losses were compared when no-load or in-load,and the eddy current loss of the rotor with different sleeve thickness in load was calculated.The influence of the initial phase angle of different driving voltages on the parameters of the machine in load was analyzed.Secondly,the high-speed permanent magnet machine is used in the open slot of the stator to optimize the alveolar structure to improve the air gap magnetic field distribution of the machine,and to analyze the influence of different relative permeability magnetic wedge on the electromagnetic parameters and performance of the machine.With the increase of the magnetic permeability of the wedge and the magnetic flux density harmonic component of the machine,the magnetic wedge has an important role in improving the performance of the machine.In addition,this paper takes 50W,100000rpm high-speed permanent magnet machine as the research model,uses four methods to calculate the stator iron loss of high-speed permanent magnet machine,and proposes an improved iron loss separation model suitable for high frequency,which greatly reduces the model.The calculation error of stator iron consumption of high-speed machine is used to calculate the loss of each part of the machine for 250kW,65000rpm high-speed permanent magnet machine,which lays a foundation for the calculation of machine temperature field,and studies the loss of various parts of the machine under different speed and load torque.Finally,this paper establishes a three-dimensional simplified model of 250kW,65000rpm high-speed permanent magnet machine,designs the machine cooling method and makes some reasonable assumptions.Combined with the electromagnetic field-thermal field-fluid field multiphysics coupling method,the temperature field of high-speed permanent magnet machine is simulated.The effects of forced air-cooled wind speed,water-cooled water flow rate and cooling water channel width on the temperature rise of each part of high-speed permanent magnet machine are calculated and analyzed.Reasonable selection of these three factors is the basis for ensuring safe,reliable and efficient operation of high-speed machines.