19. Fuzzy Based Harmonic Reduction Strategy for DC Link Inverters

The paper develops a fuzzy based methodology to improve the frequency spectrum of the output voltage and almost eliminates the need of a filter in a DC link inverter. The presence of harsh loads attempt to deteriorate the quality of the current drawn from the mains. It therefore orients to simultaneously reshape the input current phasor to a nearly sinusoidal waveform in the sense it drastically reduces the amplitude of the multiple frequency harmonic components of the input AC current. The scheme derives the reference for the PWM pulses through the use of fuzzy principles and arrives at the appropriate width for the pulses to the power switches. The frequency of the carrier is allowed to vary randomly with a view to distinctly decrease the current frequency magnitudes over the operating range. It includes the simulation results obtained using MATLAB to illustrate its potential to extract a variable magnitude output voltage in tune with the change in the modulation index. The regulated output voltage over a range of operating loads and the sinusoidal shape of the supply current substantiate the merits of the strategy and claim its applicability in the utility world.