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The DC microgrid with energy storage cells has strong stability, simple control, and a convenient power supply for DC loads, increasingly becoming the grid-connected structure of distributed generation systems. This paper presents an isolated high voltage gain soft-switching dc-dc converter suitable for DC microgrid applications. The converter comprises a dual-switch quasi-z-source network, multiplier voltage cell, and transformer. It has advantages such as high voltage gain, zero voltage switching (ZVS) of switches, zero voltage zero current switching (ZVZCS) turn-on and turn-off of diodes, and low input ripple current. The converter can achieve high voltage gain with an appropriate duty cycle and transformer turns ratio, reducing leakage inductance of transformer, which decreases the power loss and voltage spike of switch. Soft-switching of active devices increases the efficiency and decreases the output voltage ripples of the converter. The steady-state characteristics of the converter, voltage and current stress of components, the efficiency of the converter, and the selection of converter parameters are analyzed in detail. Finally, a 200 W experimental prototype is built in the laboratory for experimental verification, and the experimental results are consistent with the theoretical analysis.

BackgroundThe objective of this study is to study the adverse effects of coal mining environment on workers to discover early effective biomarkers.MethodsThe molecular epidemiological study was conducted with 502 in-service workers, who were divided into miner and auxiliary. We measured the individual levels of dust exposure for participants. Clinical examinations were conducted by qualified doctors. Peripheral blood was collected to measure biochemistry, hemogram, and karyocyte apoptosis.ResultsAll workers were healthy who have not found with any diseases that can be diagnosed medically in the physical examination and showed no difference in dust exposure level, age, height, weight, and body mass index between groups. The working years of miners were lower than that of auxiliaries (p