Design space exploration of optimized hybrid svpwm techniques for two and three level vsis

Abstract

Pulse Width Modulated Voltage Source Inverters (PWM-VSIs) are widely used in newline newlineindustry for variable speed AC drives. The quality of a PWM technique is deter- newlinemined by the trade-off between Total Harmonic Distortion (THD) and switching loss newline newlineincurred in VSI. In general the PWM techniques are hard switched in nature. Un- newlineder hard switching operation, higher switching frequency leads to higher switching newline newlineloss, EMI problem, high di/dt stress during turn on and high dv/dt stress during turn newlineoff operation. Multilevel inverters are more advantageous than two level inverter in newlineterms of di/dt stress and high dv/dt stress. However, the multilevel inverter topologies newlineprovide quasi square wave or stepped output with abundant source of odd harmonics. newlineTherefore, reductions of harmonic distortion and switching loss have been a major newlinearea of research in power electronics for PWM-VSIs. newlineThere are two popular real time PWM methods, one is carrier based PWM (Sine newline newlinePWM) and another is space vector PWM (SVPWM). The carrier based PWM pro- newlinevides good waveform quality and operates at higher switching frequency. The SVPWM newline newlinemethod has advantages over SPWM in terms of dc-bus utilization, reduced switch- newlineing frequency, low current ripple and good waveform quality. The SVPWM tech- newlinenique operates based on switching combinations of the VSI. A three phase two level newline newlineVSI has eight switching states, six active vector and two zero vector states. The newlineand#57347;exibility in placement of zero vectors result in either continuous or discontinuous newlineSVPWM. The continuous SVPWM (CSVPWM) technique provides better spectral newline newlineperformance but results in higher switching losses. The discontinuous SVPWM tech- newlineniques also known as bus clamped SVPWM (BCSPWM) techniques are effectively newline newlineused for reducing current ripple and switching loss. newline