Smart optimal control of DC-DC boost converter in PV systems

Abstract

Proportional integral derivative (PID) controllers are usually used to control DC-DC boost converters in PV systems. However, they have to be tuned based on certain defined operating range using averaged mathematical models. Loading conditions have great effect on PI controllers; PI controllers are subjected to failure under dramatic load changes. This limits the PI controller's operating range. Moreover, transient and steady state response both get affected by changing the operating range. This paper presents a novel smart-PID controller for optimal control of DC-DC boost converter used as voltage controller in PV systems. This proposed controller maximizes the stable operating range by using genetic algorithms (GA) to tune the PID parameters ultimately at various loading conditions. Then, a fuzzy logic approach is used to add a factor of intelligence to the controller such that it can move among different values of proportional gain (Kp), derivative gain (Kd) and integral gain (Ki) based on the system conditions. This controller allows optimal control of boost converter at any loading condition with no need to retune parameters or possibility of failure. Moreover, the paper presents a novel technique to move between the PI and PID configurations of the controller such that the minimum overshoot and ripple are obtained, which makes the controller very applicable for PV systems supplying sensitive loads. The controlled boost converter is used as an interface between photovoltaic (PV) panels and the loads connected to them. It converts any input voltage within its operating range into a constant output voltage that is suitable for load feeding. The proposed smart controller adapts the duty cycle of the boost converter based on input voltage and loading conditions such that it outputs a constant output voltage. A prototype system has been developed to verify the applicability of the proposed controller. Moreover, simulation and experimental results both confirm its validity as an effective and reliable controller for boost converters in PV systems and the possibility to use it in different applications.