ABSTRACT:
Specific odd harmonics can be mitigated by operating
the semiconductor switches in H-bridge inverters at optimized switching angles
of the PWM signals. These switching angles can be achieved by deriving a number
of nonlinear equations using Selective Harmonic Elimination Pulse Width
Modulation (SHEPWM) method. Modulation index (m) is a significant parameter used
to control the amplitude of the fundamental output voltage of DC-AC inverter.
By changing the value of modulation index the Total Harmonics Distortion (THD)
also will change. In this paper, the performance of single phase full-bridge
inverter using SHE-PWM scheme with varying the modulation index is evaluated.
In order to achieve a minimum THD, a different number of nonlinear equations
are used to calculate the switching angles. The performance of a single phase
unipolar inverter is simulated in Matlab.
KEYWORDS:
1. Selective Harmonic Elimination
2. H-bridge Inverter
SOFTWARE:
MATLAB/SIMULINK
CONCLUSION:
Matlab-Simulink
is used to evaluate the proposed technique in order to mitigate 3th, 5th, 7th,
9th, 11th & 13th harmonics and to verify the influence of
various condition of modulation index on THD in single-phase full-bridge H inverter.
Low order odd harmonics can be mitigated successfully by using SHE-PWM also, by
adjusting the switching angles the Total Harmonic Distortion is decreased to a
minimum of 57.47%. These switching angles are applied to generate control
signals of full-bridge H-inverter. By increasing the modulation index the THD
decreased. Also, the fundamental voltage of the inverter is maximized by
variation of modulation index with switching angles optimized.
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