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Conventional methods of a.c. voltage controllers, such as on-off control and phase-angle control are known to produce harmonic voltages in the ax. supply lines. This paper introduces the use of forced commutated techniques in a. c. voltage controllers, namely; symmetrical angle pulse width modulation technique. The symmetrically displaced pulses within the sinusoidal voltage waveform is adopted. The advantages of unity displacement factor and high frequency harmonic currents which are easy to filter, can be gained in the suggested control technique. The resulting harmonic currents from the proposed technique are analyzed and compared on a basis of the phase-angle controlled technique. Simple LC filters can be introduced in the supply input side of the voltage controllers to improve the quality of the supply voltage waveform. The analysis of harmonic currents showed that noticeable reduction is gained with increasing the number of pulses per half cycle.

Optimized Harmonics Stepped Wav Modulation(OHSW-PWM) for high vol cascaded multilevel inverter with equal commonly used in constant frequency u Stepped switching angles for cascaded mul calculated by solving nonlinear equations selected lower order harmonics. This generalized method to calculate the switchi Newton-Raphson method for solving the n which are transcendental in nature and mult Calculations of the switching angels a anticipated formula for calculating the initial paper presents solutions for 5, 7, 9, 11, inverters under different values of the mod Matlab software. The results reveal that method can be effectively used to calculate t that eliminate the selective lower order harm output voltage and reduce the total harmo experimental and simulated results proved the proposed method. Index Terms--Cascaded Multilevel In Harmonic Stepped Waveform, Selective Har PWM. Newton-Raphson method.I.

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