TITLE:
Reduction of THD in Thirteen-Level Hybrid PV Inverter with Less Number of Switches
AUTHORS:
Natesan Sivakumar, S. Sumathi
KEYWORDS:
Asymmetric Cascaded Multi Level Inverter (ACMLI), Total Harmonic Distortion (THD), Sinusoidal Pulse Width Modulation (SPWM), Field Programmable Gate Array (FPGA), Selective Harmonic Elimination (SHE)
JOURNAL NAME:
Circuits and Systems,
Vol.7 No.10,
August
31,
2016
ABSTRACT: Multilevel inverter (MLI)
is one of the most efficient power converters which are especially suited for
high power applications with reduced harmonics. MLI not only achieves high
output power and is also used in renewable energy sources such as photovoltaic,
wind and fuel cells. Among various topologies of MLI, this paper mainly focuses
on cascaded MLI with three unequal DC sources called asymmetric cascaded MLI
which reduces the number of power switches. Various modulation techniques are
also reviewed in literature[1]. In this paper we focus on
sinusoidal (or) multicarrier pulse width modulation (SPWM) which improves the
output voltage at lower modulation index for obtaining lower Total Harmonic
Distortion (THD) level. The gating signal for the 13-level hybrid inverter
using SPWM technique is generated using Field Programmable Gate Array (FPGA)
processor. The proposed modulation technique results in reduced percentage of
THD, but lower order harmonics are not eliminated. So a new technique called
Selective Harmonic Elimination (SHE) is also implemented in order to reduce the
lower order harmonics. The optimum switching angles are determined for
obtaining minimum THD. The performance evaluation of the proposed PWM inverter
is verified using an experimental model of 13-level cascaded hybrid MLI and
compared with MATLAB/SIMULINK model.