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Modular multilevel converters (M2C) are increasingly used in high voltage direct current (HVDC) systems. The efficiency of M2Cs is highly related to the modulation method which determines the switching frequency and capacitor voltage ripple in the converter station. A new approach to modulation of M2C is presented in this paper. Tolerance-band methods are employed to obtain switching instants, and...
This paper proposes a model predictive control (MPC) scheme for the interleaved dc-dc boost converter with coupled inductors. The main control objectives are the regulation of the output voltage to its reference value, despite changes in the input voltage and the load, and the equal sharing of the load current by the two circuit inductors. An inner control loop, using MPC, regulates the input current...
This paper presents a zero current switching predictive control strategy for a direct resonant converter which is part of a high voltage power supply. A voltage compensator is used to reduce the output distortion. The direct resonant converter and the voltage compensator consist of a three to single phase matrix converter supplying a series resonant circuit and an H-bridge converter, respectively...
This paper is focused on the implementation of an original algorithm for global maximum power point tracking (GMPPT) in photovoltaic systems. The algorithm detects when partial shading occurs, thus eliminating unwanted voltage sweeping. The paper gives a detailed analysis on how the algorithm succeeds in finding the global maximum power point (GMPP) in a short time and all its highlights. The system...
In this paper a 5kW step-down converter for low-voltage high-current application is presented using normally-off SiC JFETs as high voltage power switches, operating with efficiency close to 98%. Different low voltage side rectification solutions and loss estimations are also presented. As results show higher power density and efficiency can be achieved in medium- or high-power DC-DC applications by...
Blanking time, also referred to as dead-time, is one of the dominant sources of output current and voltage distortion in pulse-width modulated power amplifiers. Extensive studies are known on elimination, minimization, and compensation of the effect. Most techniques achieve a reduction of the distortion but are not capable of completely removing it. Topologies like the opposed current converter do...
The aim of this paper is to compare different models of an automatic subway in order to determine the most appropriate of them for the evaluation of the energy consumption of different studied cases (normal mode and fault-modes). Several simplified models are then deduced from a reference dynamical model and are compared in term of accuracy and computation time. A quasi-static model with an equivalent...
Due to the increasing demand for highly efficient power electronic converters, a detailed design targeting each individual circuit component like magnetic components is getting more and more important. Several electric and calorimetric methods for the loss measurement of magnetic components are known from literature. Nevertheless, only the last approach can be used to properly perform measurements...
Basic concepts with respect to stable operation of semi-autonomous low-voltage DC-grids are discussed. Design considerations on the output impedances of power electronic converters are analysed in order to avoid resonance issues within a DC-grid. With calculated or measured converter output impedances, potential resonance problems due to background harmonics between aggregated power modules and the...
This paper deals with the effect of laminations on natural frequencies of asynchronous machine magnetic core. Measurement of natural frequency of stator core is presented. Numerical model and calculation of natural frequency of core is described in next part. Comparison of measurement and mathematical model is discussed.
This paper presents a simple solution to combine three one-switch inverters in a cell sharing one EMI filter and avoiding the appearance of audible intermodulation distortion. The concept is based on making the designs asymmetric thus distributing in different frequency bands the switching frequencies. With some previous analysis to support the selection of these frequencies, no audible noise appears...
Electrolytic aluminum capacitors used in electric drive for automotive are deemed to be the weakest components of static power converters. A lot of studies have been made to estimate their aging but only for a nominal point. This paper presents a specific operation cycle implementation to study the impact of a variable and more realistic thermal cycling. Moreover, an improvement of the classical electrical...
This paper presents a new torque ripple minimization technique for a Switched Reluctance Generator (SRG). Although the SRG has many advantageous characteristics as a generator, it has not been widely employed in the industry. One of the most notorious disadvantages of the SRG is its high torque ripple. In this paper, a non-unity Torque Sharing Function (TSF) is proposed to minimize the torque ripple...
Multiple phase bidirectional DC/DC converters are developed and analyzed for optimal inductor operation, high efficiency and a low current ripple. Partial-load operational mode is investigated as well. The different opportunities to degrease the size of the inductors and current ripple and to increase the efficiency are discussed.
Conjunction of silicon crystals with surface over 10 cm² with molybdenum discs by means of silver paste sintering is being discussed. It is shown that to ensure strength of joint and low thermomechanical stress selection of dependencies of pressure and temperature on time is very important. It is necessary to ensure thermal stability of multilayer metal process on jointed surfaces. Experimental elements...
In this paper, a systematic procedure is presented, how to predict the AC resistance of litz-wire windings considering air gap fringing fields. For this purpose, an equivalent complex permeability model is derived for hexagonally packed wires. It is shown, how finite element method (FEM) can be used to determine the real as well as the imaginary part of the complex permeability with the copper filling...
A T-type three-level inverter topology with RB-IGBT is researched. The operation modes and modulation strategy is analyzed. The power loss of T-type inverter with RB-IGBT and normal IGBT is calculated and compared. Experimental results show that T-type inverter with RB-IGBT has better efficiency than that of normal IGBT.
Partial discharges (PD) are widely known to occur in medium- and high-voltage applications. Recently, it has been observed that owing to the use of modern variable frequency converters, an environment that contributes to partial discharges is also found in low-voltage motors. Low-voltage machines are vulnerable to partial discharges because their winding insulation is not designed to withstand the...
This paper presents a method for estimating the voltages at the individual sub-module capacitors of Modular Multilevel Converters (MMCs). The estimation method is designed according to a predictor-corrector scheme with a model-based prediction stage utilizing the arm current measurements and the internal modulation signals of the control system. The corrector stage is based on measurement of the total...
This paper proposes a new topological arrangement that consists in connecting the AC voltage source in series with two EIE Buck converters, one to operate in the positive half cycle and the other to operate in the negative half cycle. The control strategy is developed to achieve an AC output voltage within the limits set by standards in order to mitigate problems associated with Sags and Swells on...
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