Modulation and control of multilevel inverter for an open‐end winding induction motor with constant voltage levels and harmonics

Abstract

A multilevel inverter (MLI) with staircase waveform having maximum number of voltage levels at any desired voltage (or frequency) of a variable voltage, variable frequency application can play an important role in the modern power conversion system. In most of the control and modulation techniques of MLI, the number of voltage level reduces with the reduction of modulation index that increases the harmonic and total harmonic distortions (THDs). The variable voltage application of MLI using a single DC source of variable magnitude is the elementary concept of the proposed control technique. A cascaded MLI having unequal voltage sources with controlled magnitude can be used to increase the number of voltage levels. The closed-loop voltage control technique and a multi-winding transformer-rectifier based AC-link system is used to obtain the multiple variable voltage DC sources for the cascaded MLI. A nearest level modulation based control technique has been implemented for the MLI to obtain the fixed level voltage waveforms with constant THD and reduced switching losses. The whole control algorithm for a nine-level inverter is simulated and results are experimentally verified on a laboratory prototype of the three-phase induction motor drives.

Single‐phase Modified T‐type–based multilevel inverter with reduced number of power electronic devices

“…In energy conversion systems like electric vehicles (EVs), photovoltaic (PV), wind farms, HVDC systems, and fuel cells, multilevel inverters (MLIs) plays an important role because of its wide range of applications. MLIs have been in the focus over decades onto its attractive features like high power quality, low total harmonic distortion (THD), dv/dt stress, better electromagnetic compatibility, less switching losses, and reduced filter size .…”

A new and generalized structure of single‐phase and three‐phase cascaded multilevel inverter with reduced power components

“…Depending on the topological structure of the above reduced switch MLIs, the inverter can work with symmetrical as well as asymmetrical DC input supplies. Various hybrid topologies have also been proposed to minimize the number of components and the number of separate DC sources for high voltage and high power application . A single DC source–based three‐phase five‐level inverter and a three‐phase 17‐level inverter are obtained by cascading a flying H‐bridge power cell with a three‐level flying capacitor inverter having natural voltage balancing technique.…”

“…A single DC source–based three‐phase five‐level inverter and a three‐phase 17‐level inverter are obtained by cascading a flying H‐bridge power cell with a three‐level flying capacitor inverter having natural voltage balancing technique. Asymmetrical configuration of multilevel inverter with nine‐level and 27‐level using the single DC source for an induction motor drive is presented.…”

“…Numerous switching strategies for the MLI are reported as high frequency PWM techniques and low or fundamental frequency modulation technique. The multicarrier‐based sinusoidal PWM techniques like level‐shifted PWM (LS‐PWM) and phase‐shifted PWM (PS‐PWM) techniques, space vector PWM (SVPWM), and multireference‐based PWM techniques like triple‐reference PWM and dual‐reference PWM are all high frequency PWM techniques, whereas selective harmonic elimination (SHE) and nearest level modulation technique are the fundamental or low frequency modulation techniques that are adopted for an MLI. Single‐carrier–based PWM technique with double reference is discussed in Bhaskar et al In Bhaskar et al, non‐inverted double reference method is discussed, whereas in Bhaskar et al, a calculus‐based double reference method is discussed.…”

Cascaded H-Bridge Seven Level Inverter using Carrier Phase Shifted PWM with Reduced DC sources

“…MLI's proposed for a photovoltaic power generation [4] scheme for interfacing with ac micro grids [6]. Cascaded Multi level inverters with reduced number of power switches is presented in [7][8][9] for induction motor applications with wye connection and also for open winding connection. Multi level inverters for PV powered grid interfaced applications are presented in [10][11][12] with and without galvanic isolation between PV power and ac loads.…”