Research On SRM High-performance Drive System Based On A New Multi-level Power Conversion Circuit

Switched reluctance motor(SRM)has the advantages of simple structure,reliable operation,high efficiency,low cost,stable operation in a wide speed range and no need for rare materials.SRM has great application prospects and has been widely used in industrial transmission,electric vehicles,aerospace and other fields.In order to build the high performance switched reluctance motor drive,the key technology such as multilevel power converter circuit,reducing torque ripple based on direct instantaneous torque control and sensorless control are deeply analyzed and developed in this dissertation.SRM obtain the energy of the power supply through the power converter.Asymmetric bridge converter circuit has some limitations in SRM high-speed operation because of its speed of excitation and demagnetization is slow.In this dissertation,the advantages and disadvantages of many existing multilevel power converter circuits for switched reluctance motors are summarized,and a novel multilevel power converter circuit is proposed.The circuit has the functions of fast excitation and fast demagnetization,and can be controlled independently between each phase,besides it is suitable for SRM with any phases.This dissertation also gives a detailed analysis of each working state in the single-phase and overlapped conduction mode of the proposed circuit and discusses the selection method of the key devices in the circuit.In this dissertation,the technology of reducing the torque ripple based on direct instantaneous torque control is studied.A method of optimizing efficiency is proposed,which developing control strategy according to the variation of T/i of overlap phase.In order to overcome the defect of asymmetric bridge converter in SRM high-speed operation,the proposed multilevel power circuit is applied to the direct instantaneous torque control of SRM.The simulation results show that,the direct instantaneous torque control system with proposed multilevel circuit has better torque ripple suppression effect.Finally,the experimental setup based on the direct instantaneous torque control and the proposed multilevel power circuit is built.An over-voltage protection device is designed for the boost capacitor,which enhances the reliability of the system.The design is original and makes the multilevel circuit more practical.The SRM sensorless control is also studied in this dissertation.The SRM rotor position model is established by using BP(Back Propagation)neural network,and the precision and scale of the model are optimized by the preprocessing method to meet the requirements of real-time motor drive system.The research of SRM sensorless control for a three phase 12/8 SRM is carried out.By improving the integral formula,considering the influence of winding inductance with temperature,considering sensor delay and phase complementation,the accuracy and stability of SRM sensorless drive are improved.The experimental results show that the SRM sensorless drive has high application value.