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In this work, a gate driver with multiple stages based on switched resistors is presented. The influence of the different stages on the turn-on and on the turn-off behaviour is investigated using experimental measurements conducted on a double pulse test bench. It is shown that, compared to a single-stage reference driver, switching loss improvements are possible while maintaining the same voltage...
To estimate the short-circuit capacity of future low-voltage DC (LVDC) grids, it is important to determine the transient and steady state short-circuit (SC) current characteristics of DC-DC converter which is an integral part of LVDC grids. The study focuses on the short-circuit behavior of Dual Active Bridge (DAB) topology of DC-DC used for integrating LVDC grid applications like photovoltaic, battery...
Wide-band-gap (WBG) semiconductor devices represent an opportunity for reaching higher power densities for power electronic converters due to higher switching speeds, and thus, a size reduction of the passive components is enabled while the total efficiency of the converter is not compromised. In this paper, four SiC-MOSFETs from CREE/Wolfspeed are compared regarding their losses and performance in...
Many publications present the extension of the soft-switching range of the dual-active bridge (DAB). Unfortunately soft-switching over the entire operating area of the DAB is hard to realize. In this paper, the loss reduction of a 5 MW dual-active bridge using the auxilary-resonant commutated pole technique are derived by simulation. The aim of this technique is to improve the converter's efficiency...
This paper discusses the design of a control strategy for a three-phase dual-active bridge (DAB3) dc-dc converter, which is employed as the central converter to track the maximum power point (MPP) of a large-scale photovoltaic (PV) farm, and to deliver the generated energy into dc distribution grids. Considering the soft-switching characteristics of the DAB3 converter, two different maximum output...
An electric motor can be overloaded shortly to produce a much higher torque than the rated value due to its inherent large thermal capacitance. The state-of-the-art overload strategies are often based on the static characteristics of the motor. The real-time thermal condition is not taken into account, which leaves certain overload potential unused. This paper presents a model predictive overload...
Switched reluctance generators (SRG) are a promising solution for back-up power generation for renewable energy or in electric vehicles. Classic approaches suggest choosing single pulse control angles to minimize dc-link rms current or excitation penalty to maximize system efficiency. Those publications only investigate the effect of turn-on angle θon and turn-off angle θoff. The influence of an additional...
The critical components in electric machines must be protected against overheating. Overheating shortens the life span of the machine and causes machine failure in extreme cases. This paper presents an online temperature estimator for an automotive switched reluctance machine based on a space-resolved lumped parameter thermal network. The losses are calculated online using a pre-measured loss map...
Commonly torque ripple reduction in switched reluctance machines (SRM) is achieved with model predictive control methods, such as hysteresis or pulse width method based direct instantaneous torque control (DITC). This paper discusses the effect and possibilities when reducing the number and size of look-up tables (LUT) necessary to model the SRM in predictive DITC. The goal to only use one look-up...
This paper presents an optimization algorithm to automatically dimension the driving power stage of an electrical vehicle based on the characteristics of the motor and the driving profiles taking efficiency, cost and lifetime into account. The dimensioning process focuses on analyzing and modeling the two major components: the capacitor bank and the IGBT module in a 3-phase 2-level voltage-source...
This paper discusses the design method of a three-phase dual active bridge dc-to-dc converter (3ph-DAB) to integrate large-scale PV plants into medium-voltage (MV) dc grids. The DAB is employed as the maximum power point (MPP) tracker either on the string level or plant level. The converter's operation area is defined by the MPPs of the PV panels that are influenced by the environmental conditions...
GaN power semiconductor devices show promising properties to achieve high power densities in power converters for voltages in the range of 400 V. The utilization of high switching frequencies and high switching speeds are particularly challenging for filter design and the circuit layout. Within this paper, a comprehensive analysis of design considerations for a GaN based synchronous buck converter...
In order to develop power electronic systems with high power densities the performance of the cooling system has to be increased. Thereby, the thermal resistance of power semiconductor modules is an important design aspect. However, the thermal resistance of modules is influenced by cross-coupling effects which are dependent on the module layout and the heatsink. These cross-coupling effects are not...
For the control of high performance electrical machines, it is desirable to estimate the hot-spot temperatures in order to exploit the machine up to its thermal limits. An accurate temperature estimation can be achieved by means of high-order lumped parameter thermal networks. In variable-speed drives the thermal networks are parameter-varying due to the speed dependency of the convective heat transfer...
Switched reluctance machines have the drawback of a high acoustic excitation. This paper presents an acoustic optimization method that analyzes the signal of a vibration sensor in the control loop and is able to eliminate mode-0 borne vibrations. A search algorithm which determines the optimized control parameters is proposed. The potential of the control concept is described including measurement...
Switched reluctance machines receive increased attention by the automotive industry because of their cost efficiency. However, the comparatively larger inverter is a disadvantage of this machine type. This paper evaluates the effects of the usage of a dc-dc converter to reduce the size of the dc-link capacitor by active filtering of the source current. The active filter is compared to a passive filter...
Battery energy storage systems (BESS) are expected to increase in the number and capacity because of the increasing share of intermittent renewable energy resources in the electrical grid. Due to the cost and nature of the BESS, they are well suited for the primary reserve to balance load fluctuations in the grid. Power-electronic converters are employed for the power exchange between the transmission...
In the last decade, many projects of offshore wind farms have been planned and conducted to compliant each government policy. To increase the energy yield, attention has been paid to the replacement from AC collection grid to DC collection grid. At the moment, many applications such as electric vehicles and DC power supplies have adopted an isolated DC-DC converter with low-loss magnetic material...
The instantaneous output voltage of power electronic converters can be a very important quantity for the dynamic control of power electronic systems, such as speed transducer-less drives. Dead time effects and semiconductor voltage drop lead to massive distortion in the output voltage and can degrade control performance when the voltage reference is used. Due to the switching nature of power electronic...
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