Cascaded H bridge multilevel inverter control for grid connected DC power source

Abstract

Integration of renewable energy to the national grid is a challenging task in last three decades Many researchers had a focus on renewable energy to create new sustainable abundant and environmental friendly natural energy resources As renewable energy sources become increasingly common on the power grid the number of power electronic inverters can be expected to grow The challenges associated with renewable energy are addressed in the proposed approach through development and demonstration of Multi Level Inverter MLI architecture associated Pulse Width Modulation PWM control techniques MLI is a power electronic device that synthesizes a desired output voltage from several levels of DC voltages as inputs They have been widely used in high voltage and high power applications Synthesizing more number of levels has advantages like improved output reduced filter size electromagnetic interference and harmonics Numerous MLI topologies have been introduced over the years The three different topologies proposed for MLI s are cascaded multicell with separate DC sources diode clamped neutral clamped and capacitor clamped flying capacitors Each of these topologies has different mechanism for providing the required voltage This thesis propose Cascaded Hbridge CHB 11 level inverter topology Various switching frequency based PWM techniques such as Selective Harmonic Elimination PWM SHEPWM Optimized Harmonic Stepped Waveform PWM OHSW PWM Discrete Sine Area Equalization PWM DSAE PWM Sinusoidal PWM SPWM for constant and grid connected DC power source have been proposed to mitigate the lower order harmonics exhibited in the output voltage and current newline