Structure Design And Performance Analysis Of The New Electric Wheel

At present, central motor drive is the major drive of the electric vehicles, however, the central motor drive always needs mechanical transmission system which not only makes the chassis structure complex, narrow the vehicle space, but also cause the loss of energy and lead to the low energy utilization efficiency; at the same time, central motor drive will produce noise, which affect the driving comfort. Aiming to the problems caused by the central motor drive, the hub motor drive is used to improve by many domestic and foreign scholars in recent decades. But for the sake of the limited size of wheel hub, hub motor drive stay at the only installation of frictional brake at the present time, but there are existed thermal recession, nose, dust and other defects in single frictional brake, integrated system electromagnetic and frictional brake can solve the problems very well.Furthermore, due to the small electric braking capacity of the hub motor system, it cannot meet the requirements of vehicle’s braking performance; the motor regenerative braking is restricted by frictional brake, the characteristics of motor and so on, which make the actual braking torque fluctuated and the utilization rate of the braking force low; the electric machine for regenerative braking may cause motor overheating and even burn out the motor. However, the electromagnetic brake is smoothly, fast response and high rate of utilization of braking force, in recent years, experts and scholars at home and abroad has been working on the research of electromagnetic brake, and has provided integrated system frictional and electromagnetic brake as a new type of brake.Firstly, in this paper, the domestic and foreign related literature, the relevant structure and the domestic and foreign research progress are inquired. Then based on the three years in research work of the integrated system electromagnetic and frictional brake, it is considered that the electromagnetic brake integrated in the electric wheel can solve the problems of the current electric wheel adopts single frictional brake which cause heat fading, slowly braking reaction, a new type of integrated system electromagnetic and frictional brake of electric wheel structure scheme was put forward, the connection mode of the various parts, working principle and the size of electric wheel are detail presentation.Secondly, the structural design and parameter calculation of hub motor and electromagnetic brake are carried out in view of the provided new type of electric wheel. The software Ansoft/RMxprt is used to simulated the performance of hub motor, and the software Ansoft/Maxwell 2D is used to simulated the two dimensional transient magnetic field, the simulation result shows that the performance meets the designed requirements. Giving comprehensive consideration of the connection way as well as its structural characteristics, the structural parameters of the iron core and coil were designed and calculated.Thirdly, based on the analysis of the vehicle load, the 7 degree of freedom dynamics model of the vehicle system is established in the Matlab/Simulink, on the basis of the model, the simulations of the pure friction brake、pure electromagnetic brake and integrated brake are conducted, the simulation results show that the integrated brake can improve the braking reaction time, enlarge the braking torque.Finally, the design of hub motor, electromagnetic brake and other part of the components are sent to factory in order to produce the sample of the electric wheel, based on the sample, the power bench test of hub motor and integrated system electromagnetic and frictional brake bench test of electric wheel are developed. The characteristics of the output power and the output torque based on hub motor and the braking characteristics of frictional brake, electromagnetic brake, integrated brake based on electric wheel are studied. The test data show that the design of hub motor for sample meet the power requirements of design goals, and also meet the mounting structure with the hub, frictional brake and electromagnetic brake; the electric wheel adopt integrated system electromagnetic and frictional brake can improve the braking reaction time, increase the braking torque, and effectively improve the driving safety of the vehicle.