Temperature Field Analysis Of Switched Reluctance Motor For Electrical Vehicle

The switched reluctance motor used for electric vehicle is installed inside the wheel,with small installation space and high power density.In order to prevent the sand and raindrops from entering the motor,the closed structure is generally used,the protection grade is high,the inner heat of the motor is not easy to disperse,which leads to the high temperature of the stator winding and the bearing and the shaft.Too high temperature of the motor not only reduces the output and efficiency of the motor,but also accelerates the aging speed of the insulating layer and insulating film,and induces faults such as interturn short circuit and interphase short circuit.In the early design of switched reluctance hub motor,the accurate calculation of the temperature distribution inside the motor and the winding is of great significance for the safe and reliable operation of the motor.A mathematical model for temperature field analysis of switched reluctance motor is derived based on the theory of heat transfer.Then simulate the steady and transient simulation of the whole field temperature of a 55 kW switched reluctance hub motor under different operating conditions,and put forward a new method to optimize the temperature field by using heat pipe.The motor uses the outer rotor structure to directly drive the wheels to rotate.The main contents are as follows:First,based on the theory of heat transfer,the mathematical model of temperature field of SR motor is derived.On the premise of satisfying the calculation accuracy,in this paper,the motor winding,air gap and silicon steel sheet are treated equivalently,and the convective heat transfer coefficients of each end face are calculated.The internal heat source of the prototype is calculated by Ansoft Maxwell.On this basis,the three-dimensional structure model of the motor is established by Solidworks,and it is exported to the ANSYS Workbench software.The steady-state temperature field simulation analysis for full load,half load and light load is carried out.The overall temperature field cloud chart and each component temperature field cloud chart were obtained.Through transient temperature field simulation,the temperature rise curves of four key nodes are plotted.Then put forward a new method to optimize the temperature of the winding and the inner stator by using heat pipe.Finally,the hardware circuit and software program of the drive control system are designed.The drive control system adopts dsPIC33FJ128MC706 as the main control chip,including power main circuit,driving circuit,rotor position detection circuit and other hardware circuits.Then build experimental platform,and the temperature distribution of the prototype is tested.The error between the simulation value and the experimental value is less than 5%,which shows that the simulation analysis has high accuracy and can meet the engineering needs.It provides a basis for the design and optimization of switched reluctance motor in the future.