High Voltage gain Transformer less Fly back Converter

Abstract Conventional boost converters are unable to provide high step-up voltage gains due to the effect of power switches, rectifier diodes, and the equivalent series resistance of inductors and capacitors. This paper proposes high voltage gain transformer less Boost Converter without an extremely high duty ratio. Some dc–dc converters can provide high step-up voltage gain, but with the penalty of either an extreme duty ratio or a large amount of circulating energy. In the proposed converters, two inductors with the same level of inductance are charged in parallel during the switch-on period and are discharged in series during the switch-off period. The structures of the proposed converters are very simple. Only one power stage is used. High-efficiency, high step-up dc–dc converters with simple topologies are proposed in this paper. simple structure with a high step 1. Introduction Fossil fuels are hydrocarbons, primarily coal, fuel oil or natural gas, formed from the remains of dead plants and animals. These are non-renewable resources because they take millions of years to form, and reserves are being depleted much faster than new ones are being made. The production and use of fossil fuels raise environmental concerns. A global movement toward the generation of renewable energy is therefore under way to help meet increased energy needs. Electricity production: (i) Hydroelectricity continue to be a major resource. However, installations in main important sites are suffering from three factors: modest local consumption, the need to protect natural sites, and the shortage of financial capabilities. Still, small water heads are increasingly being exploited, especially in China, and Wind generators are being commercially distributed, either to supply electricity in long networks or to satisfy the needs for specific local applications. Some thermal power plants that burn organic residues are operational. Diverse types of solar thermal power plants are the subject of research; prototypes are being constructed and, in some cases, are already operational. Stand-alone photovoltaic systems are commercially marketed for rural electrification in developing countries. These supply electricity to isolated houses and have various professional applications. Grid-connected Photovoltaic systems are the subject of numerous demonstrations, either in the form of central stations or integrated to building facades and roofs. Research on photovoltaic lanterns indicates a considerable level of technical progress. A boost converter with a high voltage gain is used for many applications, such as lamp ballasts for automobile headlamps, fuel-cell energy conversion systems, solar-cell energy conversion systems, and battery backup systems for uninterruptible power supplies. Theoretically high voltage gain can be achieved by with high duty ratio [1]–[3]. Due to the effect of power switches, rectifier diodes, and the equivalent series resistance (ESR) of energy storage elements the voltage gain is reduced. Moreover Reverse recovery problem occurs with an operation of extremely high duty ratio [4] –[24]. A dc dc fly back converter is a very -up voltage gain and an Electrical isolation, but the active switch of this converter will have a high voltage stress due to the presence of leakage inductance of the transformer. By having less voltage stress on the active switch and recycling the energy of leakage inductance, some energy - regeneration techniques have been used to reduce the voltage stress on the active switch and to recycle the leakage – inductance energy [4]–[6]. Technique using coupled- inductor will provide a solutions to have a low voltage stress on the active switch, high voltage gain, and having high efficiency without using high duty ratio [7]–[15]. Literature includes some research of the transformer less dc–dc converters, which includes quadratic boost type [17], cascade boost type[16], the capacitor-diode voltage multiplier type [21]- [22], the voltage-lift type [18]–[20], and the boost integrating with switched capacitor technique, the disadvantage is this complex and higher cost. The switched inductor technique is used in three converters, in which two inductors with same level of inductance are charged in parallel during the switch-on period and are discharged in series during switch off period, to achieve high step up voltage gain with low duty ratio. Some conditions are assumed to analyze the steady state characteristics and operating principles i.e., all capacitors are sufficiently large, constant voltage across the capacitance, the voltage drop of diodes and on state resistance of the active switches is