Current Control of Boost Converter for PV Interface With Momentum-Based Perturb and Observe MPPT
Gautam A. Raiker, L. Umanand, B. Subba Reddy
Abstract
The tracking of power in solar PV systems depends on controlling the voltage or current to the optimum level irrespective of changes in solar irradiation. There are two aspects of maximum power point tracking (MPPT), first is to control the voltage or current and second is to find the peak power with an algorithm. This work deals with both the aspects, using current control which provides fast control response and a momentum-based MPPT algorithm for improved peak tracking. Since current programmed control gives a simple implementation and fast response of converters, it would seem obvious to link it with current referenced MPPT but this method is prone to fail when irradiation drops suddenly, leading to control loss. Voltage oriented MPPT control (which has logarithmic dependance on irradiation), with an inner current control loop is used, as it maintains control even with step changes in irradiation. The second part of this work discusses the perturb and observe (hill climbing) algorithm for finding the power peak, which is known for its simple and effective implementation. A simple modification of this algorithm by adding momentum to the hill climbing is shown to improve the speed of tracking while maintaining the oscillations around maximum power point to acceptable levels.