Abstract
This paper proposes an improved topology of the three-phase series resonant DC-DC Boost converter with variable frequency control. The DC output voltage can be properly regulated at a constant value from no-load condition to full-load condition by adjusting the switching frequency. This is feasible with the three series resonant circuits coupled to the three-phase inverter. The leakage and mutual inductances of the step-up transformer are used implicitly in the series resonant circuits. Therefore, the proposed converter, when matched to the traditional three-phase inter-leaved LLC converters, requires fewer transformers, passive components, and switching devices. Furthermore, it offers better efficiency and size reduction. The proposed SRC converter also relies on the transformer’s magnetizing inductance to ensure zero voltage switching (ZVS) for all the switches within the considered range of the operating frequency. The deployed variable frequency controller shows a good level of stability at the considered loading conditions. The output voltage-to-input voltage ratio is steadily regulated at 6:1, irrespective of the load variation, by varying the switching frequency. The experimental validation of the theoretical findings proceeded on a low power scaled-down laboratory prototype. From the achieved results, the performance of the proposed converter (in terms of its effectiveness) was validated.
1. Introduction
The recent drive for clean energy in power systems, coupled with the increasing industrial applications, such as in smartgrids, electric vehicles, and renewable energy systems, has led to a substantial interest in DC/DC resonant converters. These resonant converters have the advantages of high-frequency operations with soft switching, smooth waveforms, highpower density, and high-efficiency [1–3]. The soft switching merit undoubtedly allows the converter to experience reduced switching losses, even when operating at a high switching frequency [4–6]. The classification of the behavior of resonant converters might depend on many variables, such as their switching technique, frequency ratio, and mode of operation. A converter can achieve ZVS commutation for all switches if it achieves a higher switching frequency than the resonant frequency [7]. Alternatively, a higher resonant frequency than the switching frequency results in zero current switching (ZCS) [8,9]. Series resonant converters (SRC) are popular for many applications due to their simplicity [10,11].
6. Conclusion
In this study, a three-phase series resonant tanks SRC with variable frequency control was proposed. This conceptualized converter contains certain attributes, as follows: (a) in comparison to the three-phase interleaved LLC resonant converter, the suggested converter might decrease how many power switches. are needed. This would have a major influence, enabling weight reduction, lower cost, and a simpler circuit. (b) The utilized transformers’ magnetizing inductance provide a broad ZVS range, within which the ZVS for the entire operating range of frequency and for every switch could be achieved by the suggested converter. (c) The suggested converter’s output voltage is a six-fold increase over the input voltage. This indicates the suitability of the suggested converter for applications of high voltage. (d) With the suggested converter, variable switching frequency control was utilized and a wide load variation was maintained. This give confirmation that the load factor does not strictly affect any gain, since there is heavy reliance on the ratio of switching to resonant frequency.
