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Publicações

Publicações por Abdelrahman Elhawash

2023

A new adaptive lead-lag control scheme for high current PEM hydrogen electrolyzers

Autores
Elhawash, AM; Araujo, RE; Lopes, JAP;

Publicação
2023 IEEE VEHICLE POWER AND PROPULSION CONFERENCE, VPPC

Abstract
This paper aims at researching the design of a current controller for an interleaved Buck converter used to feed a high current 5 kW Polymer electrolyte membrane (PEM) electrolyzer representing a module stack level. The main challenge is to design a robust controller that ensures operation over a wide range of electrolyzer operating points while guaranteeing control requirements and current sharing between the converters. The developed control scheme ensures responsiveness to the requirements of the grid's ancillary services and control over the dynamics of the electrolyzer. MATLAB/Simulink simulation results with dSPACE compatible models are presented to validate the lead-lag controller, designed using root locus, achieving a ripple current of 0.1 A, a 0.3% steady-state error, and a settling time of 50 ms for a step response.

2022

ULTRA-LOW NOISE, HIGH-SENSITIVITY MEMS ACCELEROMETER FOR SATELLITE GRAVIMETRY

Autores
Garcia, S; Elhawash, M; Cabral, J; Hormigo, T; da Encarnação, T; Alves, S; Dias, A;

Publicação
2022 Solid-State Sensors, Actuators and Microsystems Workshop, Hilton Head 2022

Abstract
Satellite gravimetry requires sub-ng acceleration measurement at frequencies below 100mHz. To bring the performance of a MEMS accelerometer closer to this level, one must decrease noise sources and maximize sensitivity (to decrease input-referred electronic noise). Electrostatic pull-in based operation has great potential for high sensitivity since it relies on time transduction. Devices were fabricated with maximized proof mass (170mg over a 13x14mm2 footprint) and tuned damping coefficient (trade-off between noise and sensitivity – pull-in operation requires low Q-factors). Novel stopper designs and caps limit both in-plane and out-of-plane displacements. Devices tested using pull-in voltage-based transduction showed sensitivity of 218 V/g. © 2022 TRF.