Performance Analysis of PV Fed DC-DC Converter for Simultaneous Buck-Boost Operation

The increase penetration of Renewable Energy based Power sources (REPS) has led the emphasis on the use of DC power at the load terminals. The most REPS generate DC power and this DC power can be directly used by utilizing DC converters (DCC). Hence, DCC are trustworthy for accomplish the application of REPS. In this work a DCC is designed which is capable of bi-directional current flow as well as voltage profile with diversity. The DCC proposed can function in buck and boost mode simultaneously to meet the power and voltage ratings of various sources as well as applications. The proposed converter is energized via PV-source which supplies the DC power as per the requirement. The switching requirement of the proposed DCC is also very low with two counts. Moreover, switches can be operated with low voltage ratings which in-turn reduces the switching losses. Also, it offers negligible interference even at high switching frequencies. The proposed DC converter is designed for low as well as high power ratings voltage rating. Hence the presented DCC has various advantages in terms of voltage rating, operational modes as well as high efficiency when operated with DC various voltage ratings at the same time.

I. Introduction

The DC-Converters (DCC) are widely adopted for integrating Renewable Energy based Power Sources (REPS) [1]. The REPS like PV generates variable/fluctuating DC power at the output. This output is at a fixed value for any instant. Hence maintains a constant flow for the duration when maximum solar power is available [2]. These converters can interface numerous energy systems and also applied to the electric vehicles with diverse voltage profile for smooth operations among the loads and sources under various operation range of voltage [3]. The bidirectional DCC can transfer the energy to load as well as source with bidirectional current flow pattern. This means when required it will transfer the power to the load with current flowing from battery to the load connected and when the battery connected at the input side reaches its lowest limit, it can also be charged via the battery connected at output terminal [4]. Fig. 1 describes the application of the DCC with hybrid sources. In this figure, bidirectional DC-DC converter is presented, which can deal with multiple inputs having different voltages and also flow of power can be both the side. This means if input voltage is below the predefined limit, then current will flow from DC/AC interfacing to DC-DC side which is the functionality of buck converter. And if output voltage is greater than input one, it is boosting converter [5]. Hence in the proposed topology, flow of power is bidirectional. Such topology is helpful in maintaining the system voltage to the rated value. In literature numerous bi-directional DCC are presented but they suffer the disadvantage in terms of component count, cost, low input ripple current, etc [6–7]. These converters have poor performances dueto their low voltage conversion ratio; the voltage stress of the semiconductors is also high. Hence, this paper presents a MPC with bi-directional feature [8]. This means that the MPC can perform simultaneous function of buck or boost converter. When the power from the hybrid source is sufficiently available it will charge the Battery Storage System (BSS) [9]. In the case of low voltage profile of the source it can also provide power to the source by draining the BSS. Hence the name bi-directional buck-boost Converter (BBC) is used.