A Study On Motor Control System Of Electric Locomotive Based On Five-level Inverter

At present,the existing power locomotive transmission system mainly takes the three-level inverter output as the input power supply of the traction motor,with the higher demand for the load of the locomotive group,the future locomotive group needs to be able to work in the running state of higher voltage and higher power,Therefore,the input power supply of the transmission system of the five-level inverter as the locomotive group is the main trend of the future development.The five-level inverter power supply system involves the topology and control algorithm of the five level inverter,which requires the normal operation of the five-level inverter,while ensuring that the midpoint potential and the suspension capacitance voltage and the common-mode voltage in the inverter can be reasonably suppressed.Aiming at the control requirements,the relationship between the spatial voltage vector and the output level formed under different switching combinations is analyzed concretely,and the triangular function calculation process of the reference voltage vector is simplified by using the virtual coordinate algorithm to realize the control strategy of SVPWM.The feasibility and accuracy of the spatial vector control model of the active midpoint clamp(ANPC-5L)type five-level inverter are verified by MATLAB simulation experiments to analyze and design the control strategy problem of how to balance the suspension capacitance voltage with the midpoint potential in the five-point level inverter.Aiming at the control of traction inverter and motor of EMU,the three-phase inverter is used as three-phase input power supply of asynchronous motor,and the vector control model and principle of three-phase asynchronous motor based on rotor magnetic field orientation are analyzed,which needs to estimate rotational speed and flux in traditional vector control,and the system has great influence on external parameter change.With the problem of poor speed tracking accuracy,a sliding mode approaching law control strategy is used to improve the sliding mode control module combined with Fuzzy adaptive control system,and it is proved by MATLAB simulation experiment that the improved rotational speed and torque accuracy based on sliding mode variable structure control system is higher,and the system has good dynamic and static performance.