| The advantages of axial field permanent magnet synchronous motors consist of small size and high power density,but because of its small size and relatively closed,the heat generated during motor operation is difficult to be dissipated in time,which will lead to an increase in motor temperature rise.High motor temperature will affect the performance and service life of the motor,so it is very essential to computation the loss and temperature field simulation analysis of the motor,and design a reasonable cooling structure.In this paper,an axial field in-wheel motor with a rated power of 45 k W is used to calculate the motor losses and to study the motor temperature field and fluid field in depth.The research in this paper is carried out in the following four parts:1.Calculation of losses of each motor component.Exact computation the losses of various components of a motor is very essential,the article uses the numerical calculation method and finite element method to calculate and analyze the loss generated by the core,winding and permanent magnet of the motor on the basis of electromagnetic field theory.The effectiveness of the blocking of permanent magnets to reduce the eddy current loss of permanent magnets is verified by the finite element method.2.The temperature field simulation of the motor under natural cooling.After simplifying and assuming the motor model,the temperature field solution model is established,the model is meshed,and the boundary conditions such as heat generation rate and heat dissipation coefficient are solved,and the transient solver is selected in the thermal module of Ansys to solve the motor temperature field.Additional cooling structure is needed to cool it.3.The simulation analysis when the motor under liquid cooling conditions,the temperature field and fluid field.The cooling structure with parallel and series waterways is designed,and after the calibration of the parameters involved,it is found that the cooling structure can meet the motor cooling requirements after the calibration.After calculation to determine the coolant flow rate of 12.77 L/min,the preliminary selection of cooling medium is water,the temperature of the water inlet is set to 40℃,the temperature field and fluid field simulation of liquid-cooled motor in Fluent,after comparison and analysis,the tandem waterway scheme is selected for the research object.4.Analyze and generalization the effect of the parameters of the different coolant on the motor’s fluid and temperature field.(1)Under the premise of determining the temperature of the water inlet and the cooling medium,eight different groups of coolant flow rate of the motor were taken for simulation and analysis in Fluent,and the coolant flow rate of the motor was determined to be 10 L/min.(2)With the premise that the coolant flow rate is 10 L/min and the cooling medium is water,seven groups of different inlet temperatures are taken for the simulation analysis of the motor in Fluent,and it is determined that the inlet temperature cannot exceed 70℃.(3)Under the premise that the coolant flow rate is 10 L/min and the inlet temperature is 40℃,the motor is simulated and analyzed in Fluent with different concentrations of ethylene glycol aqueous solution from 20% to 80% as the cooling medium,and shows the basis for the selection of glycol concentration when aqueous glycol solution is used as the cooling medium. |
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