Optimizing PI Controller for SEPIC Converter with Optimization Algorithm

It is in need of a system that can step up and down the variable/fixed input DC voltage to the appropriate value depending on demand since renewable energy sources (RESs) like solar energy, wind energy, etc. are intermittent. The implementation of conventional converters with a Buck, Boost, or Buck-Boost configuration in conjunction with RESs has been widespread, although these have significant drawbacks. Pulsating input and output power, high switching losses, fabrication costs, and rating restrictions are a few of these [1]. As a result, sophisticated power converters have been developed to minimizing the ripple. The Cuk Converter, devised by Slobodan Cuk, stands out among other converters since it not only has continuous input and output currents and it also has the ability to perform in buck and boost modes by only changing the duty cycle for the circuit's single switch. Its distinct feature from other converters is its inverted output characteristic. On the other hand, high electrical stress is imposed on the electrical components during the functioning of both Cuk and buck-boost converters, which could culminate in component malfunction or overheating. SEPIC converters are able to address both of these problems. In fact, SEPIC converter helps to get noninverted output that benefits circuits from uninterrupted and precise input.

2.    Literature Review

In order to adhere to design specifications, it is important to control the input to specific sub-circuits [2]. While a converter can easily convert AC to AC, it is more challenging to convert DC to DC. Voltage bridges and diodes can reduce voltage to a certain extent; however, they are inefficient. A reference voltage can be provided via voltage regulators. Furthermore, as batteries deplete, their voltage drops, which can cause a slew of issues if there is no voltage management. There are five different kinds of dc-dc converters: First, there are Buck converters, which can only lower voltage; next, boost converters that can only raise it; finally, Cuk and SEPIC converters can perform both functions [3].

As per the application, suitable converter can be used for need bucking and boosting of voltage. It is possible, though, for the targeted output voltage to frequently fall within the input voltage range. In this circumstance, use of a converter that can regulate the voltage is the best alternative. Buck-boost converters can be less efficient since they only need one inductance and one capacitor [4]. On the other side, these converters have a lot of input current ripple. This ripple can create harmonics, necessitating the use of a large capacitor or an LC filter in many circumstances. As a result, the buck-boost is frequently costly or ineffective. Another difficulty with buck-boost converters is that they reverse the voltage. This can make them difficult to operate. Cuk converters use an additional capacitor and inductor to alleviate both of these issues. Since power converters are non-linear time-varying systems, designing controllers for systems always provides both intriguing and challenging problems [5]. The presence of duty ratio in the converter dynamics poses a considerable issue even though the most of converters can be controlled by a single switch. The development of power MOSFETs has made switching speeds of tens of megahertz attainable. On the other hand, two of the main problems with semiconductor devices associated with high switching frequency are high switching stress and switching loss.

Some of the references have been presented in Table 1as given below:

Table 1. Summary of review in the relevant area.