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The basic performance of multilevel inverters is synthesizing a proper output voltage level by using several DC sources in the input. By increasing the number of levels in the output, the generated output voltage has smaller steps, which leads to better quality output waveform. The main problem of multilevel inverters is the high power switches necessity. This paper proposes a new non-isolated DC...
This paper presents an optimized single phase DC-AC converter with RCD snubber circuit. The proposed converter has an optimized number of levels per number of switches (nL/nS) which is by far the best relationship among the converters proposed in literature. The most important characteristics of the proposed configuration are: (i) reduced number of semiconductor devices, while keeping a high number...
Multilevel converters are widely used in medium voltage applications. One of the most popular topologies in this field is the 18 pulses diode rectifier, which uses a mu Iti pu I so transformer that realizes a current harmonics cancelation that are generated by the three phase diode rectifiers. In this work an efficiency comparison of the aforementioned topology and a Multi-Cell Active-Front-End (AFE)...
Due to the possibility to drastically reduce the Solid State Transformer (SST) volume and weight, its use is becoming a reality in traction and wind power plant applications, while, in the electric distribution system, it is still considered futuristic. A SST, with managerial role in the electric distribution grid, is generally called Smart Transformer (ST). Unfortunately the low efficiency, the low...
Recently, Modular Multilevel Converters (MMCs) have received an increasing attention since this topology of converters is a viable solution for high-voltage and high-power applications. However, many research results concerning the control problems of modular multilevel converters have been proposed in the literature which the main control problems are to control the grid and differential currents...
High altitude wind power (HAWP) generating system poses several benefits over conventional wind power (CWP) generating system. An air-borne electric generator is held at high altitude above the ground surface with buoyancy provided by light gas filled blimp/aerostat. In order to minimize the size of the blimp and to reduce the number of electric components in the air-borne system, generation of electrical...
This paper investigates the design procedure of cascaded H-bridge (CHB) and modular multilevel converter (MMC) topologies for medium-voltage and high-power industrial motor drive application. The design is performed using 1.7-kV insulated gate bipolar transistor (IGBT) technology. A model is derived for multi-pulse transformer to take into account its leakage parameters' effect on converter design...
Transformerless (TL) topologies are employed in 1φ PV inverter topologies due to their small size and low weight. Avoiding the grid side transformer requires the modulation technique and the basis topology to be accordingly changed in order to mitigate dc current components in the grid side and the leakage current to ground. This paper carries out a sensitivity analysis of selected TL topologies....
The bulk materials transportation from the mines to their destination is an important activity that often represents the major part of the total mining costs. More and more frequently, high-capacity belt conveyors in mining are efficiently driven employing medium-voltage power converters connected with large induction motors. Unfortunately, medium-voltage power converters use a high number of power...
In this paper, protection of modular multilevel converter with half-bridge cells against overcurrent faults, which cannot be cleared by the converter, is investigated. Converter design with cell redundancy and a coupled branch reactor is considered. Special consideration is given to a separation of protection and permanent bypass functionality. Critical overcurrent protection design aspects are shown...
As a recently emerged topology and due to its advantages, T-type three-level converters have been gaining rapidly growing applications. This paper investigates the method to evaluate both the electrical and thermal performances of the T-type module substrate layout design. Convenient and efficient methods to evaluate stray inductance and thermal behavior within the module are used instead of the time...
This paper presents two machine drive system based on a six-phase machine (SPM) and three-leg converters. The machine is composed of two three-phase groups. For the first configuration, one of the groups is connected to a three-leg converter and the other is connected to other two three-leg converters in an open-end winding configuration (see Fig. 4). For the second configuration, one of the groups...
For connecting HV DC grids either to AC grids or to DC sources, power electronic converters (AC/DC and DC/DC topologies) in the power range from a few hundred kilowatts up to the MW range are needed. Typical requirements are: • High conversion efficiencies, even on low load conditions • High reliability and redundancy, service under system operation • Low harmonic grid impact, provision of grid support...
New prototype of an auxiliary soft-switching power supply for the tram of the city of Zagreb was developed and built based on specifications of the existing auxiliary hard-switching power supply. A new soft-switching topology for the input DC-DC converter is proposed. It was possible to compare two power supplies built to the same specifications with only one basic difference: switching technology...
Integrated-magnetic interleaved boost converters are under development for high-current, high-power applications ranging from automotive to distributed generation. The operating modes of these integrated-magnetic converters are complex and are also a function of the conduction of the lower inverse diode. A reverse-blocking diode or RB IGBT may be preferred for the lower switch, which introduces additional...
Solar inverters are designed specifically to handle photovoltaic (PV) panels, to efficiently extract the most amount of power, and to transform it properly so that it can be injected into the grid. The singularities of the application allow for opportunities that can be exploited for better performance. Inverters for PV applications are designed to operate at very low voltage variations, almost at...
This paper proposes three dynamic voltage restorer (DVR) topologies. Such configurations are able to compensate voltage sags/swells in three-phase four-wire (3P4W) systems under balanced and unbalanced conditions. The proposed systems in this work use two independent dc-links. The complete control system, including the PWM technique, is developed and comparisons between the proposed configurations...
An optimal design of a 2-MW dc supply with a variable output dc voltage range between 400 V and 1500 V, and intended for testing equipment under IEEE 1547 is presented in this paper. Trade-offs between size and system complexity must be taken into account because the main components (dc inductor, semiconductor switches, cooling system, etc.) of such a high power system are expensive and/or bulky....
With the advent of the photovoltaic (PV) energy source that has a variable and low dc output voltage, a high step-up dc/dc converter is necessary for grid-connected power conditioning systems. These power conversion systems are required to comply with strict technical and regulatory criteria to ensure a safe, reliable and efficient operation of the overall system. In this regard, this paper proposes...
A low-voltage direct current (LVDC) distribution system comprises a rectifier, a DC network, and customer-end inverters (CEI) responsible for the AC supply to the electricity end-users. The CEIs can be implemented as single-phase or three-phase ones; in this paper, feasible single- and three-phase topologies are introduced and their losses are calculated using nine different power switches. Three...
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