Advanced References and Carriers Based PWM in New Symmetrical Voltage Source Inverter

Abstract

In general, Pulse Width Modulation (PWMJ techniques of a Voltage Source Inverter (VS/) need a sinusoidal reference signal and triangular carrier signal to generate the required modulating signals for the desired output. Modifications in modulating techniques can be considered In two ways, namely modified reference and modified carrier. The existing multilevel carrier based Pulse Width Modulation (PWMJ strategies have no special provisions to offer good quality output, besides lower order harmonics that are introduced in the spectrum, especially at low switching frequencies. This paper proposes a new topology of a cascaded multilevel inverter that utilizes less number of switches than the conventional topology with a symmetrical DC source 7- level inverter. Phase Disposition (PD) strategy for Sinusoidal, Trapezoidal and Triangular reference with Triangular, Smv-tooth and Inverted Smv-tooth carrier strategy are simulated with the proposed topology, The performance has been analyzed with MATLAB/SIMULINK. By comparing the various references with various carrier strategies, it is observed that Trapezoidal signal provides less THO and higher fundamental RMS output voltage. Keywords: Total Harmonic Disortion (THO), Phase Disposition (PD), Pulse Width Modulation (PWMJ, Triangular Reference with Triangular Carrier (TRTC}.