Research On Low Torque Ripple Control Of Switched Reluctance Motor Drive System For Electric Vehicles

The popularization and promotion of new energy vehicles are both a strategic goal of the world’s automobile industry and one of the top priorities of our country’s 12 th five-year plan.As a typical representative,the deep research on the key technologies of electric vehicle(EV)is of great practical significance.Among them,the electric drive system control is one of the three core technologies in the research field of EV,undoubtedly,the more reasonable choice of the drive motor is very important.Switched reluctance motor(SRM)has many significant advantages such as simple structure,low cost,allowed high temperature rise,ability to adapt for high speed and ultra-high speed operation,strong fault tolerance,higher system efficiency and so on,it has become one of the most preferred models for EV drive motor and the research on related core technologies has become a hot spot in the field.SRM has more evident torque ripple for its unique double-salient pole structure and pulse power supply mode,this has become the most significant drawback of SRM.For a switched reluctance motor drive control system(SRD),three aspects involving the nonlinear modeling of SRM,torque ripple suppression strategy and the detection of rotor position have been studied in this dissertation.Finally,the torque ripple of SRM can be effectively suppressed to meet the actual demands.A new nonlinear modeling method of SRM is proposed.By combining the finite element method(FEM)with experimental tests,the static electromagnetic characteristics of the prototype can be gained.In view of the obvious advantages of support vector machine(SVM)in solving practical problems such as small sample size,nonlinearity,high dimension and local minima,the author focuses on the modeling of SRM based on the least squares support vector machine(LSSVM),and establishes the least square support vector machine model of flux linkage and torque characteristics.By comparative analysis with the testing results,the LS-SVM model is confirmed to have both high precision and good generalization ability,therfore,it is suitable for the non-linear modeling of SRM.An improved direct torque control(DTC)method for SRM is proposed.For the more obvious torque ripple existing in the basic DTC,by adding several new space voltage vectors within the commutation region reasonably,the improved voltage vector selection table is constructed to overcome the main drawback of the basic DTC.For the basic DTC,current chopping control(CCC)and the improved DTC,corresponding simulation models of the SRD are established to complete the simulation and comparative analysis,the results verify the effectiveness of the improved DTC.Active disturbance rejection control(ADRC)strategy is proposed to optimize the external loop to improve the torque control performance of the SRD system.Firstly,by comparing the simulation results of the linear expansion state observer and the non-linear expansion state observer,it can be found that the former is better.Secondly,based on the characteristics of SRM,the ADRC controller is designed and added to the SRD to replace conventional PI controller,the corresponding simulation and comparative analysis are completed.In the end,the designed ADRC controller is proved to be effective for the torque ripple suppression of the SRD.A new rotor position detection method of SRM is proposed.16 pole magnetic rings are combined with Hall sensors to design a kind of permanent magnet position sensor,the corresponding experimental research and vibration test have been completed.The experimental results show that the designed new position sensor can meet the requirement of the SRD system for electric vehicles.The experimental test platform of SRD is built up and the corresponding experimental tests under different conditions are completed.For the torque ripple degree of the basic DTC and the improved DTC,the corresponding comparative analysis are completed.The proposed ADRC strategy is compared with conventional PI control strategy.Finally,experimental results show that the research results in this dissertation based on the LS-SVM model,combined with the improved DTC method and under ADRC strategy can suppress the torque ripple of the SRD effectively.