Diode Clamped Multilevel Inverter Fed Induction Motor For Advanced Modulating Techniques

Abstract

In this context, the multilevel inverters with larger number of levels suitable for circuit integration are actively investigated. Diode-clamped multilevel inverters are regarded as the promising solution. As the number of voltage levels increases the harmonic content decreases significantly.The general function of the multilevel inverter is to synthesize a desired AC voltage from several levels of DC voltages. Multilevel inverters are mainly used in medium voltage and high power  applications to reduce the required voltage rating of the power semiconductor switching devices. These multilevel inverters are used to increase inverter operating voltage, to minimize THD with low switching frequency, to reduce EMI due to lower voltage steps. The advantages of this multilevel approach include good power quality, good electromagnetic compatibility, low switching losses and high capability. This project proposes to study various multilevel inverter topologies, to simulate various modulating techniques for diode clamped multi level inverter fed induction motor. These modulating techniques include sinusoidal pulse width modulation, modified reference modulating techniques. i.e., trapezoidal reference, staircase reference, stepped reference, third harmonic injected reference and offset line voltage injected reference with triangular carrier waves. The main objective of this study is to reduce total harmonic distortion, comparison of THD and fundamental component for different modulation techniques. The Simulated Induction motor model is connected at the end to observe the Stator current harmonics and speed-torque characteristics.