Design of an LPF Based Slider Controller for THD Reduction in Solar PV B-4 Inverter

Abstract

This paper proposes a Low Pass Filter (LPF) based slider controller to generate the switching pulses for Coupled Inductor Boost Converter (CIBC) and a Two-leg three phase Inverter (B-4 Inverter) topology for PV grid-connected application. The CIBC is used to step up and maintain a constant PV voltage at different irradiances. The coupled inductor technique in boost converter provides high voltage gain by maintaining a constant duty cycle. It also helps in reducing the size and cost of the system. An adaptive Maximum Power Point Tracking (MPPT)Technique is employed in this paper to track the fast change of solar irradiance, so as to improve the dynamic response of the system. A B-4 Voltage Source Inverter (VSI) is introduced for highly efficient and medium power PV application. The B-4 inverter reduces the PV system size and cost when compared to a conventional inverter. Moreover, B-4 inverter is useful to reduce Total Harmonic Distortion (THD) of grid voltage and current. From the simulation results, it can be seen that the proposed LPF based slider controller gives constant converter and inverter output voltages with less THD and grid is operating at unity power factor.