Research On The Control System And Experimental Prototype Of NPC Three Level Inverter

Multilevel technology has been widely used in high-voltage and high-power field because of its advantages such as reducing the withstand voltage of switches,reducing the voltage stress of switches,improving the quality of output waveform and improving the voltage and power level of the system.At present,in the field of high voltage and high power,the topology of diode clamped three level inverter is the most widely used.This paper mainly studies the control system of diode clamped three level inverter.In order to control the three-phase output voltage waveform,the load disturbance for processing based on the established mathematical model of three level inverter in three-phase ABC coordinate system,and through the coordinate transformation,the mathematical model under synchronous rotating coordinate system,the three phase flow two-phase flow into the direct,simplified the mathematical model.The instantaneous value PI control of the two DC components of the d axis and q axis of the inverter is carried out to suppress the fundamental wave disturbance.On the basis of theoretical research,the SVPWM of three level inverter closed-loop control method is simulated based on MATLAB,the simulation waveform can be seen visually: SVPWM control method is correct and effective,can achieve three level inverter function,and three-phase three level inverter circuit in the double closed-loop control scheme,output the voltage and current waveform,the effect is very good,fast dynamic response and disturbance,verify the correctness of the control scheme.Then the neutral point potential balance control based on space vector is introduced,and the simulation research is carried out.The simulation results show that the neutral point potential balance strategy of space vector is effective,and it can suppress the fluctuation of midpoint potential well.An experimental prototype of three level inverter controlled by TMS320F2810 DSP is designed in this paper.The experiment results show that the closed loop control using dual loop instantaneous value had good inhibitory effect on the output voltage of the fundamental disturbance;using space vector with adaptive factor K control algorithm is proposed in this paper,inhibition of midpoint fluctuations have better effect.