The grid tied PV systems without transformer have some benefits such as low cost, weight and size and also increases the overall efficiency. The galvanic connection between the grid and PV system causes leakage current in the transformerless inverter to flow through pa More
The grid tied PV systems without transformer have some benefits such as low cost, weight and size and also increases the overall efficiency. The galvanic connection between the grid and PV system causes leakage current in the transformerless inverter to flow through parasitic capacitors between the PV system and ground and causes personal safety problems, increases the output harmonic spectrum, and system losses. This paper introduces a modified single phase two stage transformerless inverter for grid connected photovoltaic systems with low leakage current. The neutral of the grid is directly connected to the negative terminal of PV panel that eliminates leakage current without complex control strategy. In this paper, a Proportional Resonant (PR) control strategy is used to control the injected current. The performance of the transformerless inverter is analyzed and its structure has been simulated in PSCAD/EMTDC and the obtained results tested experimentally.
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critical inductance is one of the factors that decides continuous, boundary or discontinuous conduction mode of dc-dc converters. In applications like mining, the Continuous Conduction Mode (CCM) and consequently safety of converter can be guaranteed by proper selection More
critical inductance is one of the factors that decides continuous, boundary or discontinuous conduction mode of dc-dc converters. In applications like mining, the Continuous Conduction Mode (CCM) and consequently safety of converter can be guaranteed by proper selection of inductance. So, calculation of critical inductance and proper sizing of inductor is an important issue in designing of dc-dc converters. In this paper, a non-isolated n-input buck dc-dc converter is introduced. Then, the operational modes and energy transfer process is investigated and discussed in detail. The critical inductance is calculated for 3 and 4-input versions. Using the inductive reasoning, a generalized relationship is proposed for calculation of critical inductance of converter with any number of inputs (n-input version). The proposed generalized relationship not only reduces the amount and time of calculation in design stage, but also presents a better view of performance of converter. The 3 and 5-input version of converter has been modeled and simulated in PSCAD/EMTDC software. Also, the 3-input version of converter has been practically implemented. The obtained simulation and experimental results confirm the validity of proposed generalized relationship for critical inductance calculation of n-input buck dc-dc converter.
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