A Novel Fault-Tolerant Switched Reluctance Motor For Belt-Driven Starter Generator Of Micro-Hybrid Vehicles

With the energy crisis and environment pollution becoming much more severe,more and more attention has been paid on the belt-driven starter generator(BSG)which is the primary micro-hybrid technology.Different from other types of BSGs,a switched reluctance motor(SRM)for BSGs has many distinguished merits,such as robustness,low cost and wide applications in serious environment and high speed,it will be a potential focus on BSGs.Research on a novel fault-tolerant SRM for BSGs(SRBSG)in micro-hybrid vehicles is made,including electromagnetic optimation,starting/generating performance analysis,mutual inductance and fault tolerance performances analysis,thermal analysis and research on prototype experiments.The main research works of this dissertation are as follows:1.Accoding to low fault tolerance caused by high mutual coupling under more two phase excitations simultaneously,a novel fault-tolerant SRBSG is proposed.Based on its working principle and mathematical modeling,two-dimesional finite element model of this motor is carried out,static and dynamic performances,including flux linkage characteristics,inductance characteristics,torque characteristics,transient current and output torque are analysed.When it comes to low output torque caused by little ratio of maximum inductance and minmum one,the main factors which influence the output torque including the stator and rotor pole arcs(?s and ?r),the inner diameter of the stator(Dsi),the radial height of the rotor segment(hcr),the selection of the turn-on angle ?on and the turn-off angle ?off are chosen to be optimized.The final simulation results reveal that the output torque of the SRBSG meets the requirement,iron loss reduces,and torque ripple declines.2.Control strategy about starting/generating performance of the SRBSG is developed and its starting performance under chopped current control and its generating performance under angle position control are good.In addition,comparative study of mutual coupling and fault-tolerant performance between the proposed SRBSG and the conventional SRM is proposed.The simulation results show that dynamic performance and fault-tolerant capacity of the proposed SRBSG is superior to the convetional SRM due to its little mutual coupling.Moreover,torque and iron loss performances in the proposed SRBSG with different types of winding connections are compared,the results reveal that not only the output torque is largerwhen the winding connection of the SRBSG is NSNSNSNS,but also the torque ripple is smaller.3.The steady temperature distribution of the SRBSG under rated speed condition is analysed in ANSYS.Thermal conductivity factor and convection coefficient in different parts are introduced in detail.It is found that temperature in different parts of the motor is up to a reasonable value that allows the motor to run stably and long.The experimental study verifies the correction of the simulation.4.The prototype is installed to complete the experiments about static inductance,torque measurement and load test.Meanwhile,hardware circuit design based on D2 P controller is also developed to support the dynamic motor experiment,including power driving circuit,position signal conditioning circuit,current sampling circuit,current chopper and overcurrent protection circuit,optocoupler isolation and logic protection circuit.