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Fulltext LLC resonant converter with series-connected primary windings of transformer for PEV battery charging

Shahid Iqbal, Imran Shahzad, M., Soib Taib

Pertanika Journal of Science & Technology, 2017;25(101):85-94.
MyJurnal

This paper proposes a half-bridge LLC resonant converter with two resonant tanks for plug-in electric
vehicle (PEV) battery charging. Each resonant tank is connected with one of the centre-tapped primary
windings of the power transformer. Both resonant tanks are fed alternately by a half cycle of the switching
pulse in one period. The converter is designed to operate below resonance zero-voltage switching (ZVS)
region to reduce switching losses and to achieve output DC voltage range 250V-420V with 400V input
DC voltage for depleted PEV battery. MATLAB Simulink is used to simulate the circuit with 1.5 kW
maximum power and the simulation results show that the converter can meet the constant-current,
constant-voltage (CC-CV) charging requirements of the depleted PEV battery.
Fulltext A single-stage led driver with voltage doubler rectifier

Nurul Asikin, Shahid Iqbal, Mohamad Kamarol, Mohd Jamil

Pertanika Journal of Science & Technology, 2017;25(101):9-18.
MyJurnal

In this paper, a configuration of a single-stage AC-DC converter and a high voltage resonant controller
IC L6598 for LED street light driver is discussed. The converter is obtained by integrating two boost
circuits and a half-bridge LLC resonant circuit. A voltage double rectifier circuit is adopted as output
to lower the voltage stress on transformer and the associated core. The two boost circuits work in
boundary conduction mode (BCM) to achieve the power factor correction (PFC). The converter works
in soft-switching mode allowing the power switches to operate in zero-voltage-switching (ZVS) and
the output diodes to operate in zero-current-switching (ZCS). This reduces the switching losses and
enhances the efficiency. The converter features lower voltage stress on the power switches and the bus
voltage is reduced to slightly higher than the peak input voltage. Therefore, the converter can perform
well under high-input-voltage. Here, the DC bus and the output filter capacitances are greatly reduced.
So, electrolytic capacitor-less converter can be realized for a long lifetime LED driver. Simulation results
from PSpice are presented for a 100-W prototype.
Fulltext Assessment of quality of work life (QWL) among healthcare staff of intensive care unit (ICU) and emergency unit during COVID-19 outbreak using WHOQoL-BREF

Bilal Maqsood M, Ashraful Islam M, Zeb-Un-Nisa, Abbas Naqvi A, Al Qarni A, Fuad Al-Karasneh A, et al.

Saudi Pharm J, 2021 Sep 20.
PMID: 34566456 DOI: 10.1016/j.jsps.2021.09.002

Objective: The study aimed to document the quality of work life (QWL) among healthcare staff of intensive care unit (ICU) and emergency unit during COVID-19 outbreak using WHOQoL-BREF.
Methods: A multicenter cross-sectional study was conducted for two months (May - June 2020) among healthcare staff working in intensive care units (ICUs) and emergency units of the hospitals under National Guard Health Authority (NGHA) across five cities of Saudi Arabia. The study used the WHOQoL-BREF instrument to document the QWL through an electronic institutional survey. The data was analyzed through IBM SPSS version 23. The study was approved by an ethics committee.
Results: A total of 290 healthcare professionals responded to the survey. The mean overall quality of life score was 3.37 ± 0.97, general health = 3.66 ± 0.88, domains, i.e., physical = 11.67 ± 2.16, psychological = 13.08 ± 2.14, social = 13.22 ± 3.31 and environment = 12.38 ± 2.59. Respondents aged > 40 years, male gender, married status, being a physician and, having a work experience > 15 years and no extra working hours, had higher mean scores for several domains of Quality of life (QoL), overall QoL and general health (p < 0.05).
Conclusion: The QWL among healthcare staff during COVID-19 pandemic was low. Demographic factors were mainly the determinants for a higher QWL while extra working hours was determinant of lower QWL. Despite the pandemic, no COVID-19 related variable affected the work life of healthcare staff.

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