A novel multicell DC-AC converter for applications in renewable energy systems

Abstract

This paper presents a novel dc-ac converter for applications in the area of distributed energy generation systems, e.g., solar power systems, fuel-cell power systems in combination with supercapacitor or battery energy storage. The proposed converter is realized using an isolated multicell topology where the total ac output of the system is formed by series connection of several full-bridge converter stages. The dc links of the full bridges are supplied by individual dc-dc isolation stages which are arranged in parallel concerning the dc input of the total system. Therefore, all switching cells of the proposed converter can be equipped with modern low-voltage high-current power MOSFETs, which results in an improved efficiency as compared to conventional isolated dc-ac converters. Furthermore, the cells are operated in an interleaved pulsewidth-modulation mode which, in connection with the low voltage level of each cell, significantly reduces the filtering effort on the ac output of the overall system. The paper describes the operating principle, analyzes the fundamental relationships which are relevant for component selection, and presents a specific circuit design. Finally, measurements taken from a 2-kW laboratory model are presented.

A DC/DC Converter for Clean-Energy Applications

“…Algorithms like improved perturbation and observation method (Femia et al, 2009), sliding mode observer technique (Kim et al, 2006), or some others (Park et al, 2006;Kwon et al, 2006) are used to track the maximum power point (MPP). In order to increase the system efficiency is preferred to have low voltage with the solar cell array (Ertl et al, 2002), and also some wind systems generate relatively low voltage. Therefore, converter in these application require boosting type converters, Figure 3 shows different topologies which provide current to the ac-mains.…”

“…Dc/dc is used for increasing the output voltage at a constant level allowing interaction to ac mains on the inverter stage, which is employed in order to perform the MPPT and deliver a sinusoidal current to the utility line. Converter illustrated in Figure 3(b) has also two stages: multiple isolated dc/dc converters and a multilevel inverter (Ertl et al, 2002); first stage is mainly used for isolation purposes and the next one to provide sinusoidal current to the ac mains. It is normally found in literature systems which combine the power from two or more sources.…”

Analysis of an Interleaved Resonant Converter for High Voltage and High Current Applications

“…In DC/DC converter, power MOSFETs with 900V voltage stress will result in high turn-on resistance. Three-level converters [4][5][6][7][8][9] with low voltage stress and high switching frequency have been presented in DC/DC converters for high voltage applications. Based on the neutral-point clamped diodes or flying capacitor, the voltage stress of active switches is clamped at V in /2.…”

Analysis and Implementation of a New ZVS DC Converter for Medium Power Application

“…Although high frequency MOSFETs with 900V voltage stress can be used in the rear DC/DC converters to overcome this problem, the high cost and large turn-on resistance are the main drawbacks of the high voltage MOSFETs. Three-level converters/inverters [1][2][3][4][5][6] have been proposed to use low voltage stress of power switches for high voltage applications. The neutral point diode clamp converters, flying clamp converters or series full-bridge converters have been presented to limit the voltage stress of power switches at one-half of DC bus voltage.…”

“…The components of circuit 1 include 4 , D 3 and D 4 and the circuit 3 shown in Fig. 1(e 6 , D 5 and D 6 . Circuit 1 and circuit 2 are …”