Design and Control of a Grid-connected Seven Level Inverter for Photovoltaic Applications

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Francis Mulolani Francis Kafata Esau Zulu

Abstract

This paper presents the design and closed-loop current control of a grid connected seven-level, 3-phase diode-clamped multilevel inverter for Photovoltaic (PV) applications. The proposed closed loop current control technique is based on the voltage-oriented proportional integral (PI) controller theory. The modulation technique used is level-shifted-carrier sinusoidal pulse width modulation (SPWM). The gain values of PI controller were selected to achieve good current quality and dynamic response. Grid synchronization was achieved by using a synchronous-reference frame phase-locked loop (SRF-PLL). Matlab/Simulink was used for the control system design and simulation. The simulation results show that a 1.34% total harmonic distortion (THD) of the output current was achieved which is within the allowable current distortion limits by international standards. The stability of the system was analyzed using pole-zero mapping and root locus.

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How to Cite
MULOLANI, Francis; KAFATA, Francis; ZULU, Esau. Design and Control of a Grid-connected Seven Level Inverter for Photovoltaic Applications. Zambia ICT Journal, [S.l.], v. 3, n. 1, p. 21-27, mar. 2019. ISSN 2616-2156. Available at: <http://ictjournal.icict.org.zm/index.php/zictjournal/article/view/72>. Date accessed: 19 oct. 2019.
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