The Research And Design Of Three Level Variable Frequency Speed Regulation System Based On DSP

Energy shortage and environmental pollution are common problems for human beings,in this backgrounds,our country have put forward two alternatives,namely clean alternative and electric energy alternative,while electric energy consumed mainly in high voltage and large capacity motor.Every switch of the three level inverter stress half of the DC side voltage,so it is widely used in the field of high voltage and large capacity variable frequency speed regulation.In this paper,based on the analysis of multilevel converter,the vector control theory of three level inverter and the SVPWM modulation algorithm of the three level inverter are studied.Based on the the asynchronous motor of the mathematical model in the coordinate system,analysised the rotor field oriented induction motor vector control principle and estimation method of state observer based on MRAS speed;analysis the SVPWM modulation algorithm based on ??? coordinate system and the SVPWM modulation algorithm based on 60° coordinate.Because the SVPWM algorithm in the 60° coordinate system is easier to digital controlled,the modulation algorithm of three level inverter is determined.At the same time,the reason of the unbalance of neutral point potential of the three level inverter is analyzed,and the improved method to control the neutral point potential balance is given.In this paper,the three level vector control system simulation platform is built,and the simulation model of the three level variable frequency speed regulation system is carried out.The simulation results shows that the SVPWM algorithm is correctly in the 60°coordinate system,and the improved algorithm of midpoint potential balancel reduces the deviation of the neutral point voltage and improves the performance of the system.This paper takes TMS320F28335 DSP as the control core,set up the experimental platform of three level inverter system,the circuit parameters are selected,and designed software in the CCS 5.5 environment,completed the overall system debugging.On the basis of the relevant experiments,the experimental waves are studied,which shows the correctness of the theoretical analysis and the feasibility of the system design.