Study On Control Strategy Of7.5kW/380V Switched Reluctance Drive System

The research topic in this thesis is an important part of the projectScraper Conveyor Drive System (Serial Number:110148032), which isthe College Students’ Innovation and Entrepreneurship Project sponsored byTaiyuan Science and Technology Bureau. It is proposed in order to furtherimprove the dynamic performance and loading capacity, at the same timerealize its function of braking. According to requirements that applying tothe practical field, the single-double-phase excitation mode has been studiedin chopped current control mode and then the optimization of turn-on angleand turn off angle is proposed. The function of braking has been realized.The main content of this paper is as follows:The developmental trend of SRM and defects in the practicalapplication are analyzed on the basis of domestic and overseas relevantliterature reviewing and site investigation, then the main content of thispaper is seriously determined.The electromagnetic torque of12/8poles switched reluctance motors isrelatively smaller in single-phase excitation mode at low speed. To solve thisproblem, a single-double-phase excitation mode which is suitable forthree-phase switched reluctance motor was proposed. The torque-anglecharacteristics of the prototype were calculated by finite element analysis.The conclusion that electromagnetic torque in single-double-phaseexcitation mode is larger than single-phase excitation mode is obtained byanalyzing the torque-angle characteristic. The maximum load experimentwas taken when motor is in two different excitation modes. It has beenshown by the experimental results that carrying capacity of the motor at lowspeed can be significantly enhanced in single-double-phase excitation mode. The turn-on angle and turn-off angle were optimized while motor is involtage PWM control mode and could adjusted according to load to reducethe variation of motor speed rate.Taking into account the requirements that SRM needs to stop quickly insome applications, the energy consumption bake function is increased.Energy flow is analyzed when motor is braking. Current chopping controldetermines is selected as braking control strategy and discharge circuit isdesigned. The experiment of motor energy consumption braking control wasexperimented. The result shows that the current chopping control strategy iseffective and the motor could stop quickly.Through the analysis of relevant references the entire drive systemstructure and working principle of each part. The inductance and torquecharacteristics of motor were analyzed in the quasi linear model. Accordingto the relationship between the inductance, flux, torque and rotor positionsignals in the finite element analysis method,12/8pole model of switchedreluctance motor was established.Based on the nonlinear of the SRD system and magnetic saturation ofthe motor, this paper applies fuzzy control methods to the SRD system. Theoverall dynamic simulation model of SRD on MATLAB is developed. Thetraditional PI control, fuzzy-PI control, adaptive fuzzy-PI control are used tocompare with eath other in the simulation.The simulation for speed respondand anti-interference ability of the motor has been implemented.It has beenshown by simulation results that speed respond and anti-interference abilityof the motor are significantly improved with the method of adaptivefuzzy-PI control.