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Transient system-level simulations of future DC grids require modeling the behavior at the terminals of the power system's components, and thus also of power converters. The internal electrical variables of the power electronic devices are not relevant in such simulations. Based on this, this paper presents an approach for eliminating all the internal electrical nodes of a single-phase Dual-Active...
Switched reluctance motors are an alternative to conventional rotating field machines due to their robust mechanical design and low-cost production. In automotive drives the application of a dedicated algorithm for torque ripple reduction is indispensable as otherwise mechanical resonances in the drive train are excited. In this paper an automotive-sized high-speed SRM drive is investigated for two...
Due to the increasing number of power-electronic components connected to the grid, medium-voltage dc (MVDC) grids are a promising alternative to established ac distribution grids. Within this work, the advantages and additional flexibility of substations for (urban) railways connected to future MVDC distribution grids are investigated. Possible topologies are presented and the efficiencies are compared.
In this paper, different high frequency inductors for a DC-DC converter for electric vehicles are designed and compared. The interleaved bidirectional DC-DC converters are good candidates to boost the battery pack voltage to the required voltage level, so that the traction inverters operate in an efficient manner. The use of wide bandgap devices allow to decrease the passive component size, as the...
In the design or simulation phase of a power electronics converter, it is, among others, necessary to have accurate power semiconductor loss models. Such models can be extracted from datasheet values, but they do quite often not cover a wide variety of parameters such as dc-link voltage, temperature or even gate resistance. A double pulse test bench [1] was designed and built to measure switching...
This paper presents a galvanically isolated gate driver system for medium voltage SiC-MOSFETs. A low common mode coupling capacity of 1 pF and good electrical insulation of the gate driver power supply are achieved by using a current-loop AC-bus power supply. The power semiconductor is protected against unintentional self-turn-on by a low resistance gate path that is active while the gate driver is...
A bidirectional DC-DC converter with high voltage gain and wide input and output voltage range is presented. The input voltage range is 30 V to 60 V and the output voltage range is 100 V to 400 V. The nominal power is 10 kW. The converter is based on a Dual Active Bridge in which the voltage range has been extended with a tap changer between the transformer and the high voltage H-bridge.
This paper presents a modification of a test bench which has been built for device characteristation. The test bench is able to measure the static losses (blocking and forward conduction) and the dynamic losses (turn on and turn off). To have a comparison of devices designed for soft-switching applications and devices for converters in hard-switching applications the existing test bench is modified...
DC grid technology is regarded as a promising solution for future electric networks integrating a great amount of renewable energies. It calls for high efficiency dc-dc converters with high step-up ratio to interconnect medium voltage (MV) dc distribution grids and high voltage (HV) dc transmission grids. This paper presents an isolated soft-switching dc-dc converter combining two-level converters...
Dc-dc converters are a promising technology for interconnection of future dc grids. Besides the relatively low volume and space requirements, dc-dc converters provide good controllability of the power flow. This is particularly important with regard to a more decentralized energy generation, where a fully bidirectional power flow — even between grids of equal voltage levels — is desired to increase...
In this work the spatial electro-thermal modeling of power electronic modules is discussed. It is shown how physical and mathematical modeling techniques can be combined to obtain a compact time efficient electro-thermal simulation framework for power electronic modules. The framework can be used to evaluate the transient temperature distribution of a power module in an electric vehicle over driving...
The three-phase dual-active bridge (DAB3) converter is a promising topology for high-power conversion in future dc grids due to bidirectional power flow, inherent soft-switching capability and reduced filter size. However, the conventional single phase-shift control (SPS) does not allow the soft-switching operation with large voltage variations in light load conditions. This paper proposes an asymmetrical...
Recently, the transformerless design of medium-voltage (MV) drives is an emerging design concept of variable-speed drives (VSD). Here, no dedicated feed transformer is used. The VSD is directly connected to the on-site facility transformer, where multiple other loads are connected as well. The benefits of such a transformerless VSD are the reduced total volume, weight, losses and system costs. However,...
Recently, the transformerless design of medium-voltage (MV) drives is an emerging design concept of variable-speed drives (VSD). Here, no dedicated feed transformer is used. The VSD is directly connected to the on-site facility transformer, where multiple other loads are connected as well. The benefits of such a transformerless VSD are the reduced total volume, weight, losses and system costs. In...
Circuit breakers for direct current (DC) are a key component for implementing multi-terminal DC networks. DC circuit breakers are already available for low voltage (LV) level and have been investigated in the high voltage (HV) level. This however leaves a gap in the medium voltage (MV) level, where neither technologies from the HV or LV could directly provide a satisfying solution. Different circuit...
Circuit breakers for direct current (DC) are a key component for implementing multi-terminal DC networks. DC circuit breakers are already available for low voltage (LV) level and have been investigated in the high voltage (HV) level. This however leaves a gap in the medium voltage (MV) level, where neither technologies from the HV or LV could directly provide a satisfying solution. Different circuit...
The connection system of offshore wind parks with the onshore power grid can have a crucial impact on the overall energy yield. The possible (ac and dc) connection systems for offshore wind parks are investigated in detail and compared both in terms of cost and losses. Both conventional copper (Cu) cables and high-temperature superconductor (HTS) cables are considered in the case of dc systems. An...
With increasing share of the intermittent renewable energy resources in the grid, battery energy storage systems (BESS) are becoming increasingly important for the primary reserve. One possible way to connect such large BESS to the existing ac grids is by using medium-voltage (MV) multi-megawatt voltage-source converters (VSC). In these grid-connected converters, an LCL filter is often used to comply...
The potential of medium-voltage dc (MVDC) grids in various applications has been under investigation by different researchers. In several works, the advantages of implementing MVDC technology into collector grids of wind and photovoltaic (PV) parks are pointed out. The main driver is that the grid-side inverter of the distributed generators as well as lossy grid filters and bulky 50 Hz transformer...
In this paper a 2 MW dc-dc converter is presented and design criteria are carried out. It deals with the preliminary design for the hardware implementation. The power supply shall have multiple targets such as an PV emulator or supply for a dc-micro grid in the research facility National Center for Reliable Electric Power Transmission of the University of Arkansas. The converter is designed for an...
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