In recent year the electrical energy transfer is done by the converters made of semi conductors had became immense problem by injecting undesirable harmonic effects in the electrical equipments, in order to rectify these drawbacks pulse width modulation rectifiers are replaced in the place of phase controlled rectifiers having capability of controlling the harmonics, by implementing pulse with modulation technique.

These pulse width rectifiers having   low harmonic distortion i.e. THD is below 5%, maintains unity power factors, and attains nearly sinusoidal controlled output with bidirectional power flow.  And these are in expensive, operates at high switching states with high power applications.

Here modulation is nothing but varying the properties of one signal by using another signal know as carrier signal, Pulse width modulation is mainly classified into Single pulse width modulation, multiple pulse width modulation, Sinusoidal pulse width modulation, Trapezoidal pulse width modulation, Staircase pulse width modulation, Delta pulse width modulation having various switching strategies, Natural sampled , Regular sampled , Optimal Sub-optimal  these entire phenomenon’s and their operation principles are elaborately explained in this paper.

Our project we provided the basic information regarding the strategies of various harmonics and their reduction techniques. These harmonic creates an abnormal behavior of the electrical equipment like decrease in power factor, over heating of the system, decreasing the efficiency and damaging the equipment.

Hence there is an immediate need for reduction of these harmonics, so we provided the necessary solutions for the reduction of harmonics. Harmonic filters are used to reduce the harmonics by improving total harmonic distortion. Harmonic analysis is carried out by a mathematical approach Fourier series.

Our project is simulated by using MATLAB/SIMULINK software, the simulation results shows that a controlled output nearly equal to sinusoidal is obtained by using pulse width modulation, this paper reveals that PWM is low cost approach for protection of electrical accessories which can be easily installed with simple circuit logic; it reduced the total harmonic distortion to a greater extent.

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