Novel Modeling and Nonlinear Control of the Siwakoti-H Inverter Considering Flying Capacitor Voltage Balance for Photovoltaic Applications

The Siwakoti-H inverter (SHI) with a flying capacitor is a recent addition to the transformerless inverter family, suitable for grid-connected single-phase photovoltaic systems. It offers a promising alternative to traditional topologies without the need for transformers, due to its minimal power electronic components. However, one of the key challenges in managing flying capacitor (FC) inverters is ensuring that the voltage of the FC remains within the desired range. Materials and Methods: To tackle this issue, first, a novel nonlinear model of the SHI is obtained defining two control inputs and two control outputs, and then a nonlinear feedback linearization (FBL) control design is proposed for the SHI when connected to a single-phase grid. This article introduces a novel approach to the modeling and control of the SHI enabling simultaneous control of both the injected current to the grid and the flying capacitor voltage. The proposed modeling and the designed control method play a crucial role in maintaining the capacitor voltage within the specified range and in tracking a sinusoidal reference for the injected current into the single-phase network. A PWM implementation of the proposed control is also suggested which is useful in the practical setup. The obtained model can be extended for the SHI with other line filters and it can be used to design more sophisticated controllers for SHI. The simulation and practical results presented in this study demonstrate the effectiveness of the proposed modeling and control approach.

کلیدواژه ها:

feedback linearization ، flying capacitor ، photovoltaic ، Siwakoti-H inverter