Efficiency comparison of direct dc-ac power conversion system and conventional power conversion systems
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Date
2018-06
Authors
Muhammad Najwan Hamidi
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Abstract
Multilevel inverters are gaining popularity especially in medium to high power
applications. Today, direct DC-AC inverters with the like of cascaded H-Bridge and
modular multilevel (MML) Half-Bridge configuration are becoming much more accepted
due to their vast advantages compared to older conventional inverter configurations such
as neutral-point clamped and flying-capacitor inverter. This study focussed on efficiency
comparison between these direct DC-AC inverter and conventional inverter topologies
based on grid link application. The purpose is to get a clear overview of the performance
of tested inverter topologies. The efficiency evaluation was fully performed by using
PSIM simulation software package. For every selected inverter topology, the output
power, DC link voltage, semiconductor devices configurations and pulse width
modulation (PWM) method were kept constant for a fair comparison between them. In
controlling the power, real power-reactive power (PQ), proportional-integral (PI) based
direct-quadrature (DQ) control scheme was implemented in all selected topologies. As
for the PWM method, In Phase Disposition Level Shifted PWM (IPDPWM) was used
since it produces decent output harmonic performance with minimum components. From
the simulations, it was observed that direct DC-AC inverters have better efficiency
performance in overall compared to conventional DC-AC inverters where their minimum
efficiencies were around 98.3 % and able to reached up to 99.1 %. On the other hand,
conventional DC-AC inverters’ efficiencies ranged from 98.1 % to 99.0 %.