طرح هماهنگ سازی مبتنی بر استخراج حامل برای مبدل های DC-DC در میکروگریدهای DC Carrier extraction based synchronization scheme for distributed DC–DC converters in DC-Microgrid

1. Introduction The new trend in future power generation systems is developing toward Distributed Generators (DGs), which means that energy conversion systems are situated close to energy consumers and large units are substituted by smaller ones [1]. The integration of these DGs, energy storage systems, and distributed electric loads through the point of common coupling is called a Microgrid (MG) [2]. MGs can be configured into DC (DCMG) and AC (ACMGs) based on the power electronics interface circuits that will be used [3]. Recently, there has been a general upsurge of interest in using DCMGs being described as flexible, intelligent, and active power networks [4]. In addition, they are able to improve system reliability, efficiency, and security leading to promote and increase the renewable energy sources integration [5].In DCMGs, a DC–DC boost converter is a key element to interface DGs to the MG’s DC-bus [6]. Various DC–DC boost converters topologies have been studied in Refs. [7–12]. DCMGs along with their DC–DC boost converters still face numerous challenges such as ripple contents of the MG DC- bus voltage and current [13]. Indeed, voltage and current ripple are among the various phenomena that contribute to a reduction in lifespan of power sources and energy storage devices interfaced to the DC-bus [14,15]. Multi-Phase Interleaved Boost Converters (MP-IBCs) are introduced in applications such as electric vehicles to interface different DC power sources to a common DC bus achieving low ripples contents in the input current and the output voltage [16,17]. The pulse width modulation (PWM) signals ofthese converters are generated based on multiple carriers with the same frequency and different phase angles. The synchronization of these multiple PWM carriers are quite easy since all the PWM modulators are driven from the same controller and hence the same oscillator [18]. In addition, the phase angles can be easily considered as 360/N where N is the number of converters as mentioned in Ref. [19]. In applications such as DCMGs, each DG along with its converter has its own local controller (LC) and hence its own oscillator which makes the PWM carriers synchronization is a big challenge. This challenge is related to the frequency drift of each oscillator due to temperature and component tolerance. This drift will create a continuous change in the phase shift angle between PWM carriers of each converter [20,21]. To ensure the most accurate synchronization process, it should be taking into account clock drift and start latency by using the available real-time system integration [22].