Analysis and non-linear control of SEPIC dc-dc converter in photovoltaic systems

Abstract

SEPIC dc-dc converter has multiple applications as a power conditioning system because it has a nonpulsating input current and its voltage ratio is both step-down and step-up. However, due to the non-linear characteristics of a SEPIC converter, a non-linear control is more suitable to attain better performance in voltage regulation. We designed a Sliding-Mode control and a passivity-based control for controlling both the output voltage of the SEPIC converter and the input voltage to reach the maximum power of a photovoltaic module. This paper presents the stability analysis and the design of the two non-linear controllers. The simulation results show a good performance of both controllers with fast transient responses and zero steady errors. However, the Sliding-Mode control shows less inductor current than the Passivity-Based control. These results confirm the good performance of non-linear control for a SEPIC converter in photovoltaic systems; we expect experimental validations in future work.

Comparitive Analysis of Fuzzy Based MPPT for Boost and SEPIC Converter Topologies for PV Application

“…It is a class of Switched mode power supply converter containing at least one uncontrolled switch and one controlled switch and for Ripple reduction purpose filters are connected to the output of the converter. The input-Output relationship for continuous conduction mode is given by (5) The above relationship shows the output voltage is greater than the input voltage. The output resistance of the converter Ro connected to the panel can be writtened according to Rpv as shown in below equation.…”

“…There are many types of converter out of them most identified Power converters are the Buck Converter, the Boost converter and Buck-Boost converters. [3] [4].There are several techniques to control input voltage of DC Converter [5]. Among various control methods FLC is uncomplicated and simplest to be used with PV system.…”

Nonlinear control methods for single-ended primary-inductor power converters

“…then (7) thus the system is globally asymptotically stable (GAS). The duty cycle variation u is treated as input signal to stabilize system in (5).…”

“…The most common technique is utilizing a sliding mode control as in [4]- [6]. This method requires less inductor current, but results in larger ripples in voltages and currents compared to the passivitybased control as concluded in [7].…”

“…Our motivation in this paper is to present the nonlinear model of SEPIC converters in detail and investigate different control laws. In [7], the model is presented with PV system dynamics. However, this is unnecessary since the capacitor in the solar panel side is typically large and its dynamic performance is much slower compared to that of the power converter.…”