Model-based MPPT with Corrective Ripple Correlation Control

Abstract

This paper presents a novel method for obtaining the control gain for the integral control law of Ripple Correlation Control (RCC) for Maximum Power Point Tracking. The control gain in the standard RCC is not straightforward to obtain and does not adapt to significant changes in irradiance and temperature. Our proposed method is based on estimating the maximum power point (MPP) value for a given solar panel model as a function of irradiance and temperature. We then uses a PID controller to set the control gain such that MPP is attained. The paper starts with a review of basic concepts of ripple correlation control. Next, we present a curve fitting approach for estimating the maximum power point. The set point is then used along with the measured value of power to obtain an error signal for the PID which generates our adaptive/corrective control gain k. We then present simulation results for several irradiance settings. A sensitivity analysis and an analysis on the number of points required for the MPP fit are then presented. Finally we compare the proposed model based RCC to the traditional RCC.