Conference Papers

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Author: search.filters.author.Muhammad Ramees, M.K.P.

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    Sliding Mode Observer Based Open-Circuit Fault Detection in the HERIC PV Inverter
    (Institute of Electrical and Electronics Engineers Inc., 2022) Muhammad Ramees, M.K.P.; Ahmad, M.W.; Brahmendra Yadav Gorla, N.B.Y.
    Grid connected transformer-less Photovoltaic inverter known as highly efficient and reliable inverter concept (HERIC) is derived from the industrial-standard full-bridge topology with two additional switches on ac side. This paper presents a detection and localization method for open-circuit (OC) failures in the semiconductor switches of HERIC inverter. Fault detection based on sliding mode observer (SMO) is proposed for the ac bypass switches and an average current estimator is used to detect failures in the main switches of full bridge inverter. Two parallel SMOs are developed based on the state space model of the converter under different OC fault conditions in ac bypass leg. Observed grid current and measured grid current are used to obtain the residual which determines the location of OC fault in the inverter. The key advantage of the proposed method is that it does not require additional sensors for fault diagnosis which will improve the system robustness. Efficacy and reliability of the proposed method is validated using simulation studies. © 2022 IEEE.
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    An Online technique for estimation of the C and ESR of DC link capacitor in a boost converter based on multiple harmonic injection
    (Institute of Electrical and Electronics Engineers Inc., 2023) Muhammad Ramees, M.K.P.; Waseem Ahmad, M.
    Aluminium Electrolytic capacitors (AEC) are widely used in DC-DC converters. Health of the capacitor can be monitored using the capacitance and equivalent series resistance (ESR) as the ageing will decrease the capacitance and increase the ESR. Hence the estimation of these parameters is essential for the diagnosis of AEC. So, in this paper a method for the estimation of the capacitance and ESR are proposed. This method is based on the injection of low frequency current harmonics into the converter by modifying the duty ratio. A group of harmonic currents are injected, and corresponding voltage and current ripples are obtained using DFT analysis which is used to calculate the impedance at each frequency. From these impedances the capacitance and ESR are estimated using Least Mean Square (LMS) algorithm. Detailed simulation is carried out using MATLAB/Simulink and results are included in this paper. © 2023 IEEE.
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    Open-Circuit Fault Detection and Identification in Neutral Point Clamped Inverter via Sliding Mode Observers
    (Institute of Electrical and Electronics Engineers Inc., 2023) Muhammad Ramees, M.K.P.; Saywan, Y.A.; Ahmad, M.W.
    Neutral point clamped (NPC) inverters offer a range of advantages, including reduced switching loss, decreased harmonic distortion in output voltage, minimized emissions impact, and improved efficiency. However, System reliability becomes a significant concern in NPC inverters due to their higher susceptibility to failures due to the increased number of power electronic switches in comparison to conventional two-level inverters. Power electronic switch faults, particularly open circuit faults, can potentially lead to cascaded failures within the system. To address this issue a sliding mode observer-based method is proposed in this paper. The effectiveness of the method is evaluated through detailed simulations using MATLAB/Simulink. The results demonstrate the capability of the sliding mode observer in accurately detecting open switch faults, contributing to enhanced fault diagnosis and improved reliability of NPC inverters. © 2023 IEEE.