A Soft-Switched Grid-Connected DC/AC Inverter with Low Current Ripple
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2019-04-29
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Renewable energy sources will soon be responsible for mainstream power generation. The energy produced by these sources needs to be conditioned to compatible forms for the utility grid system. The power conditioning can efficiently be performed through power electronic converters. Thus, power electronics is one of the key technologies for renewable energy harvesting systems. Because the utility grid infrastructure is based on AC, DC/AC inverters are commonly used in renewable energy harvesting systems as the interface to the utility grid. The focus of this thesis is on the design and development of highly-efficient DC/AC inverters for future energy systems. Typically, the industrial DC/AC inverters are based on simple full-bridge circuits with hard switching. However, hard-switching imposes several difficulties on the performance of DC/AC inverters. Thus, increasing the efficiency and decreasing the switching losses of these inverters have been an active research area. In particular, soft-switching techniques have long been one of the beneficial solutions to reduce the switching losses and, consequently, enhance the overall efficiency of the inverter. However, existing soft-switching techniques usually use extra active/passive components along with a complicated circuitry. Therefore, most of the inverter products use simple and reliable full-bridge structures with hard-switching. This thesis presents a soft-switched DC/AC inverter for low power applications (i.e., high voltage, low current applications). The proposed circuit is based on the conventional full-bridge structure in conjunction with integrated magnetics. The integrated magnetics performs the ripple steering to provide zero voltage switching for the power semiconductors and attenuate the current ripple at the output of the inverter. Theoretical analysis, simulation results, and experimental results are presented to verify the feasibility of the proposed inverter and demonstrate its superior performance.
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Ghatreh Samani, R. (2019). A Soft-Switched Grid-Connected DC/AC Inverter with Low Current Ripple (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.