The Journal of Engineering (Apr 2020)
Closed-loop control of a single-stage switched-boost inverter in modified DC-interconnected nanogrids
Abstract
Switched-boost inverter (SBI) is a single-stage power converter suitable for interfacing between photovoltaic (PV) arrays and loads. Although, it has many advantages such as it's not requiring an expensive complex dead-time circuitry, yet its duty ratio is limited between 0 and 0.5. This means that it has some difficulties in increasing both the DC-link output voltage and its AC-output voltage. So, most researchers proposed it for low-voltage power applications or using with step-up transformers. Accordingly, this study contributes towards improving the performance of the SBI for being used in the modified nanogrid within an open energy system. It introduces a novel approach closed-loop control technique to overcome most of the inverter drawbacks. Also, it enhances both the DC-link and the transformer-less rated AC output voltages to a sufficient value suitable for feeding domestic loads. And in the same time, the proposed robust controller utilizes a hysteresis band for balancing between voltage stability and PV-maximum power achievement. This research also includes a more sophisticated fast-charging slow-discharging control strategy for the battery energy management system that depends on a bidirectional buck-boost converter. Test results ensure the robustness of the proposed controller against sensitivity, nonlinearity, and time-variant parameters of the overall system.
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