Research On Direct Torque Control System Of Three-Level Inverter-Fed Induction Motor

This paper disscusses and researches the diode Neutral Point Clamped(NPC) three-level inverter-fed induction motor direct torque control system. At the beginning of this article describes a multi-level inverter topology and asynchronous motor speed control method. The first part of the article is the theoretical research, describes several models of multi-level inverter, and explained each model. At the same time it introduces the NPC three-level inverter working principle, deduced the mathematical model of the inverter and related issues. Then analysis the principle of NPC three-level inverter-fed induction motor direct torque control(DTC) system. From the vector coordinate transformation, DTC principle, hysteresis comparative control, voltage space vector selection, and many other aspects of a detailed analysis of the theoretical part of the research project, prepare the ground for the later study.The latter part of this article based on the theory studied in greater depth. First, utilize computer simulation software MATLAB / Simulink tool kit, include direct torque control algorithm, 3/2 coordinate transformation, flux observer, vector synthesis method principle simulation. Simulation results verify the feasibility of the system design ideas, and then basis on the existing experimental conditions debugging and design the relevant circuit hardware. Using the TI company DSP controller TMS320F2812 as the based controller, combined with CCS software debugging environment, design-related procedures, realize system debugging.Finally, by using the existing laboratory conditions, select a 1.1kW induction motor as subjects for direct torque control experiment. In the last article we give the results of experiments.