A Direct PWM Voltage Controller of MPPT & Sizing of DC Loads for Photovoltaic System

Abstract

In a photovoltaic (PV) system, the appropriate voltage regulation is essential to guarantee the maximum power operation. In this paper, a direct pulse width modulation controller based on a single gain ( k ) is presented. This controller directly estimates the duty cycle ( D ) through gain k, and simultaneously its mathematical operation contains the properties of integral controller. Initially, a comprehensive study is presented to evaluate the D values according to reference points on I–V curves with contrasted irradiance levels. This study has been carried out for resistive and battery loads. Based on critical observations, separate tuning expressions of k gain have been designed for resistive and battery loads. It is revealed that with regard to varying weather, k gain is dynamic for resistive load, while static for battery load. Moreover, it is also shown that inappropriate setting of load will limit maximum power point tracker controller to reach the MPP point. Therefore, two more expressions have been presented to configure the resistive and battery loads. Comparative analysis between different D-schemes is presented, which indicates that for both loads, the proposed scheme has the superior performance with less complexity. Finally, numerous experimental tests have been conducted to verify the tuning criteria and working principle of the proposed scheme.