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Hybrid LV ac/dc microgrids are being considered for commercial buildings which bring new design requirements for the multiport converter aimed to interface both ac and dc grids. In this paper, we explore the potential to use two well-developed topologies for this targeted application. An optimization-based genetic algorithm which allows to find the best possible choices among different off-the-shelf...
The modular multi-level converter is an upcoming topology for drive application in the megawatt power range. This paper presents a comprehensive reliability survey for this kind of converter which can be used for its optimal designing. In this survey, converter total failure rate, is calculated for different number of output levels to find the optimal condition in which converter can provide the best...
This paper presents the DC analysis of the Negative Output Elementary Luo Converter (NOELC), which includes the continuous-conduction mode (CCM) voltage gain and the boundary condition between the CCM and the discontinuous-conduction mode (DCM). The main features of the NOELC are the high gain with small ripple and the reverse output. Additionally, we address the parameters design of the NOELC and...
This paper proposes a transient modeling and analysis method for the fractional-order DC-DC converters in continuous conduction mode (CCM), in which a fractional-order Buck converter is taken as an example. By extending the usage of equivalent small parameter method (ESP), the converter is modeled by a general state vector differential equation. Then by adopting the principle of harmonic balance,...
A novel control strategy is proposed for a bidirectional multiport single phase two stage microinverter without electrolytic capacitor. The application of this converter is for power factor correction under non-linear grid tied load. The converter is composed of a triple active bridge series-resonant DC/DC converter cascaded with a voltage source inverter where a film capacitor is used in the DC-Link...
The MMC is an emerging and highly attractive multilevel converter topology for medium and high voltage applications. Various modulation strategies are being used to control the MMC system. Balancing the cascaded submodule voltages and eliminating the second order circulating current in the leg of the MMC system are the main concerns of many researchers in the area of MMC system. Mostly, for circulating...
In this digest, a coupling coefficient estimation method for wireless charging system is proposed based on its transmitter and receiver current and voltage harmonics analysis. One of the main challenges of wireless charging in vehicular application is the significant variation of magnetic coupling coefficient between transmitter (Tx) and receiver (Rx) coils due to large air-gap and lateral misalignment...
In this paper, a cost-effective and reliable equivalent series resistance (ESR) estimation method for aluminium electrolytic capacitors used as DC-link capacitors in front-end rectifier fed inverters is proposed. The proposed method is based on the extraction of switching frequency components of DC-link voltage and current using band-pass filters. A limiting value of switching frequency is identified,...
This paper presents a novel control method that enables operation of Modular Multilevel Converters under non-sinusoidal AC supply conditions based on frequency domain decomposition of supply voltages. The proposed control method enables to inject or draw near sinusoidal grid currents even during the presence of harmonic distortions in the supply voltages without the use of additional hardware filters...
The modular multilevel converter (MMC), is widely adopted in high voltage applications because of its simplicity and modularity. However, the current and power flow is very complicated. As a result, methods proposed for capacitor reduction, which is required to stored line frequency related circulating energy, all went through complicated mathematical derivation. C. Li proposed a state plane analysis...
Multilevel inverters are high voltage, high power devices with wide electrical applications due to their lower output harmonic component and device stress management capabilities. Manifold control strategies have been proposed and implemented for MLIs and fundamental frequency switching strategies are especially suited due to their ability to provide for higher efficiency. This paper proposes a hybrid...
Since the capacitor equivalent series resistance (ESR) above 1kHz almost stays constant, dc-link current root-mean-square (RMS) closed form equation is an easy way to evaluate the capacitor losses from the switching harmonic currents (SHCs). But when the ac current contains multiple low order harmonics (LOHs), their impacts on the dc-link has not been systematically studied. In this paper, a straightforward...
Modular multilevel converter (MMC) has been proved a prospective topology in high voltage and high power occasions. Hybrid MMC mixed with half-bridge (HB) and full-bridge submodules (FBSMs), which achieves a good tradeoff between power devices quantity and dc short circuit fault handling capability, attracts extensive attention. In this paper, the characteristics of SM capacitor voltage ripples are...
Reliability of dc-link capacitors in modern design of power electronic converters is an important aspect that needs to be considered. The requirement of applying condition monitoring for health status estimation in many reliability-critical applications have been a focused demand. The existing capacitor condition monitoring methodologies are suffering from shortcomings such as, low estimation accuracy,...
This paper discusses a power rectifier based on a cascaded topology composed of a three-leg cell and three H-bridge cells. Each leg of the three-leg cell is cascaded connected to an H-bridge cell. Since different types of converter are series-connected, the topology is assumed to be hybrid. The capacitors of the H-bridge cells operate as floating capacitors. It is shown that the discussed topology...
This paper presents a new topology of multilevel converter that allows to increase the number of output voltage levels reducing the numbers of semiconductors necessary in comparison with the standard multilevel converters like Active Neutral Point Clamped (ANPC) and Stacked Multicell Converter (SMC). This new topology called Reduced Multilevel Converter (RMC) consists of a tandem connection of basic...
In order to reduce the size of high-voltage flying capacitors in the five-level hybrid-clamped inverter, an improved modulation strategy based on phase-shifted PWM (PSPWM) is proposed in this paper. The four carrier waves are redistributed and the charge/discharge time of the high voltage capacitor can be largely reduced. The only disadvantage of this PWM scheme is that the harmonic characteristic...
Harmonic and interharmonic distortions are considered as the main power quality issues especially in the distribution networks. The double-stage Adjustable Speed Drives (ASDs) in which the front-end diode rectifier is connected to a rear-end inverter through an intermediate DC-link filter may inject significant amount of harmonics and interharmonics into the grid and consequently degrade the grid...
In this work an ac-dc-ac multilevel power converter is investigated. The developed configuration is composed of one single-phase ac-dc-ac three-leg module and two H-bridges, one of them connected in the shared part of the system to employ multilevel voltages to input and output converter, and the other one connected on the grid side for input overvoltage. The converter is employed in applications...
This paper presents an ac ripple repression method for neutral-point voltage of three-level inverter system with electrolytic capacitor less. To reduce the volume of three-level inverter system, electrolytic capacitor with huge capacitance is must eliminated from dc-link. In the inverter system applying film capacitors, however, the ac ripple component in neutral-point voltage of dc-link is increased...
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