Analysis of Single Switch, CUK/SEPIC based Multi-Port Converters

Abstract
Multi-port converters are used to combine two or more energy sources to give it to the load so as to meet the peak load demand. It achieves high conversion ratio and high efficiency, thus the voltage inputs are boosted to give higher output voltages due to its high voltage gain and the voltage step up capability. The objective is to achieve the voltage step up capability by using the Renewable Energy Sources such as the Wind Energy Systems and Photovoltaic Systems. Here the comparison between the three different PFC converters have been made and thus the SEPIC based PFC is found to be less harmonic and efficient. The Single Switch and the SEPIC/CUK based Multi-Port converters have been simulated and the voltage and Harmonic values have been compared using MATLAB/SIMULINK Software.
Keywords:Multi-Port Converter, FSTPI, SEPIC, SSTPI.
INTRODUCTION
Multiport converters interfacing with several power sources and storage devices are widely used in recent years, independent power converters used for each of the energy sources, common high-voltage or low-voltage DC bus is used to interconnect multiple sources. Existing multiport structure is inherently complex also overpriced due to the multiple conversion stages and communication devices between individual converters [1]. Based on power electronics technique, the diversely developed power conditioners including dc–dc converters are essential components for clean-energy applications. Generally, one power source needs a dc–dc converter either for raising the input voltage to a certain band or for regulating the input voltage to a constant dc-bus voltage [2].
However, conventional converter structures have the following disadvantages: 1) large size; 2) complex topology; and 3) expensive cost. In order to simplify circuit topology, improve system performance and reduce manufacturing cost, multi-input converters have received more attention in recent years. The isolated dc–dc converter has multiple input ports for connecting different sources, such as Battery, photovoltaic (PV) panels, wind turbine generators (WTGs), fuel cells, and so on[3]. The multiport dc–dc converter not only regulates the low-level dc voltages of the sources to a constant high level required by the inverter, but also can provide other important control functions, such as maximum power point tracking (MPPT), for the renewable energy sources. [7]
A High step-up multi-port dc-dc converter has the following advantages:
1. High voltage conversion ratio is achieved by using coupled inductors.
2. Simple converter topology which has reduced number of the switches and associate circuits.
3. Simple control strategy which does not need change the operation mode after a charging/discharging transition occurs unless the charging voltage is too high.
4. Output voltage is always regulated at 380 V under all operation modes.
The multiport AC/ DC-DC converter can be used to interface multiple power sources and storage devices. It regulates the system voltages and manages the power flows between the sources and the storage elements [4]. For small hybrid power systems, the multiport concept can provide a reduced parts-count solution compared with the conventional structure that uses multiple converters [5], [13]. A multiport converter may best satisfy integrated power conversion, efficient thermal management, compact packaging, and centralized control requirements.