Electronic equipment's require supply voltage with different values that can create a stabilized
voltage at the output in the conditions of changing the source voltage and load current. The flyback switching converter is a suitable option for producing different voltag More
Electronic equipment's require supply voltage with different values that can create a stabilized
voltage at the output in the conditions of changing the source voltage and load current. The flyback switching converter is a suitable option for producing different voltages in such conditions.
Due to the high frequency switching, the electromagnetic components with significant power are
directed from the converter side to the power lines and also radiated to the surrounding space,
which causes electromagnetic pollution and EMI radio interference. In this article, an effective
and practical method for designing and adjusting the EMC electromagnetic compatibility filter
is presented. Adjusting the filter values is based on averaging the noise circuit by considering its
equivalent impedance. In most of the proposed methods for filter design, the noise source is
assumed as an ideal current source and the equivalent impedance of the noise is not considered.
This reduces the accuracy of the design and prevents the correct filtering of the components in
some frequencies. In this article, the circuit averaging of the entire structure of the converter is
done by considering the parasitic elements, because the closer the presented model is to the real
structure, the more effective the filter is, and the more effectively it removes radio interference
components. In the end, the software simulation shows the accuracy and efficiency of the
proposed method in EMI filter design.
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In this paper an interleaved boost-flyback converter which was suitable for network connections of renewable energy sources is presented. Because in the solar system applications, level difference of the converter input and output voltage is high, boost converter cannot More
In this paper an interleaved boost-flyback converter which was suitable for network connections of renewable energy sources is presented. Because in the solar system applications, level difference of the converter input and output voltage is high, boost converter cannot be used. Due to problems of the boost converter such as hard switching, voltage stress is equal to the output voltage. As regards in electronic converters, the power tends to increase the switching frequency to improve the converter response and increase its power density, hard switching caused to reduce converter efficiency. Also high voltage stresses of components have forced the designer to use semiconductor elements which can withstand in high voltage which will increase the losses in the converter and reduce its output. The proposed converter using LC resonant tank and auxiliary switches provides soft switching condition (ZCS) for the main converter. Interleaved techniques have used for reducing input current ripple and increase the size of the output capacitor and also boost-flyback converter have used to enhance converter gain and reduction of voltage stress of semiconductor components. The operating principle of the proposed converter is presented in this paper.
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In this paper, a ZVS interleaved flyback converter with two transformers is presented, which consists of two active clamp flyback converters and the main switch of one converter acts as an auxiliary switch of another converter. This converter has less auxiliary elements More
In this paper, a ZVS interleaved flyback converter with two transformers is presented, which consists of two active clamp flyback converters and the main switch of one converter acts as an auxiliary switch of another converter. This converter has less auxiliary elements and less voltage and current stress compared to similar soft switching interleaved flyback converters. The introduction of a new auxiliary circuit for soft switching, in addition to increasing efficiency, minimizes the number of added semiconductors. Also, another advantage of this structure is the applicability of the provided auxiliary circuit to other isolated converters. The soft switching conditions in this converter are created by the auxiliary circuit in such a way that the converter switches turn on and off under ZVS conditions and the converter diodes turn on and off under ZCS conditions. The efficiency of the proposed ZVS interleaved flyback converter at full load is increased by 5%. Another advantage of the proposed converter is that the Q2 switch, in addition to providing zero voltage switching conditions for the Q1 switch, it also transmits energy and increases the density of the converter power and reduces the current stress. The converter is thoroughly analyzed and a 300W laboratory prototype is made to confirm its correct operation and practical results are presented.
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Electromagnetic compatibility in switching power converters which are noise sources themselves, has a special importance. Electromagnetic interference (EMI) in the form of conducted or radiated reaches to sensitive sections and interferes with their operation. On the ot More
Electromagnetic compatibility in switching power converters which are noise sources themselves, has a special importance. Electromagnetic interference (EMI) in the form of conducted or radiated reaches to sensitive sections and interferes with their operation. On the other, electromagnetic compatibility (EMC) standards causes another forces to reduce noise in switching converters. Major part of noise is due to the common-mode (CM) current passes through parasitic elements to the circuit ground (Earth). One of the important parasitic elements from the CM noise viewpoint is the switch heat-sink capacitor (common-mode capacitor). In this paper, a cancellation method of the heat-sink capacitor via a passive circuit is proposed in a 50W isolated flyback converter and is also modeled in OrCAD software. Also, experimental measurement results of the CM electromagnetic interference in regular and proposed flyback converter prototypes are presented to examine the modeling accuracy. Based on the experimental results, significant reduction of CM-EMI is verified after applying the cancellation method of the heat-sink capacitor.
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