This paper proposes a new enhanced-boost non-transformer-based impedance source network. The strong boosting ability of the proposed topology is realized by making use of the switched capacitor concept in the formerly introduced enhanced-boost quasi Z-source network (EB-qZSN) without any additional active switch. Meanwhile, the advantages of the EB-qZSN such as input current continuity and shared ground between the input and the output are maintained. In addition to the lower shoot-through requirement to obtain high voltage gains, the proposed impedance network takes advantage of a smaller size of passive components along with a lower input current ripple to achieve higher power density and higher efficiency. Moreover, the lower total rating of the switching elements, defined by switching device power, directly translates to lower cost for the proposed method. The operation principles and the design guideline of components are explained in detail and a thorough comparison with other ZSN is presented. A 240W DC-DC prototype converter was built to validate the performance principles and properties of the proposed impedance network. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
This paper proposes a class of impedance networks, called quasi-Δ-source, as an improvement to the successful Δ-source one. Compared to their origin, the three proposed networks offer higher voltage gains with a better magnetic circuit utilization and a smooth continuous input current. A lower magnetizing and total inductance required for the Δ-shaped coupled inductors of the proposed networks allows smaller and cheaper magnetic cores utilization. Also, a lower total power loss of the magnetically coupled elements is another interesting advantage of the proposed networks. Moreover, the total required capacitance of the proposed networks is the same and even slightly lower than that of the conventional Δ-source one. All these improve the performance of the proposed class of networks with the smaller size of components compared to their conventional competitor. The principles of operation are developed and the theoretical analysis is performed. Also, by using the circuit averaging technique, the small-signal models of the Δ-source and the proposed networks are derived as well as their control-to-output transfer function is achieved. Finally, the experiments on a 300 W rated power prototype of the proposed networks successfully confirm the theoretical achievements. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
The Y-source impedance network is truly referred to as the origin of the magnetically coupled impedance source (MCIS) inverters. The key characteristics, including high boost capability and design flexibility, are associated with the coupled inductor turn ratio. However, the magnetic element brings some practical challenges, such as voltage spikes, high shoot-through (ST) current, and bulky coupled inductors. This paper proposes two new Y-source inverters with clamped DC-link voltage. Due to the high boost ability, they are suitable for single-stage high gain inversions. Additionally, the significant reduction in the amplitude of the ST current leads to a reduction of the total power loss and capacity of the reactive component. Another attractive characteristic is that the Y-shaped coupled inductor's stored energy is no longer affected by the power rating of the converter, as a result of the zero dc magnetizing current. All these contribute to the high efficiency and power density of the proposed converters. The design guidelines of the components are presented and a thorough comparison with the state of the art is carried out. The achievements are then confirmed through extensive tests on a 500W laboratory setup.
The use of coupled inductors in impedance source inverters improves the voltage gain performance at the expense of high dc-link voltage spikes and shootthrough (ST) currents. The result is an increase in voltage and current stresses on semiconductors, as well as reactive element capacity and overall losses. Thus, to overcome these problems, this letter proposes a new family of magnetically coupled impedance source (MCIS) inverters with a smooth dc-link voltage, a low ST current, and a higher voltage gain that are confirmed through experimental tests.
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