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This paper proposes seamless frequency synchronization scheme for fast mode switching of parallel grid-connected inverters operated by droop control in stand-alone mode to grid-connected mode. The proposed scheme analyzes the phase difference between the grid and the inverter for fast frequency synchronization and predicts the synchronization time for frequency increase and decrease. By selecting...
This paper proposes optimal switching period phase-shifted method for slave inverter to reduce grid current ripples in synchronized two parallel three-phase grid-connected voltage-source inverters (VSI). In parallel operation, a 180 degree phase shifted method generally takes of advantage of reducing grid current ripples in same DC-link voltage for each grid-connected VSI. However, in case of unequal...
This paper presents three three-phase AC-DC configurations in which two are unidirectional and have reduced switch count. The investigated topologies have one DC-link and are composed by two converters in series connection through transformers, that process part of the total power, while the conventional converters have two DC-links and a transformer processing all the power. The replacement of switches...
Renew able energy sources have gained momentum in the current trends of effective power generation to overcome global warming due to the pollution caused by existing power generating system. The renewable power will also meet the future demand when existing fuel will be exhausted. Solar power is considerably preferred on account of its easy availability all year round. In this paper, a very efficient...
Cascaded Multi-level inverter for synchronization of power generated from PV system to utility grid is reported in this paper. Inverters are prone to several types of faults e.g. switch failure or dc link capacitor failure. Failure mode analysis of cascaded H-Bridge is widely discussed in the literature. Various methods for post-fault operation with reduced capacity (due to module failure) but with...
In this paper, a renewable energy based wind-PV microgrid is investigated for seamless transfer between the grid connected and isolated modes according to the grid availability. The VSC (Voltage Source Converter) based voltage and current controls are used to provide smoothness in both the operations. A battery bank is connected at the DC bus of VSC for load leveling during low power generations or...
This paper discusses a design approach of an isolated type of single phase power converter that uses a matrix converter (MC) with a LC active buffer for the on-board vehicle battery charger in PHEV/EV. The MC is advantaged in terms of size due to the lack of DC bus, where the electrolytic capacitor is not required as direct conversion of AC/AC is possible. However, in the case of single phase, the...
The penetration of Distributed Generators connected to the electric grid requires today new control strategies in order to participate in local ancillary services. This paper presents a control strategy for a Front-End Converter enhancing not only these new requirements but also the intentional islanding for a portion of the public medium voltage distribution grid. The simulation of the proposed control...
Wireless charging is developing into a standard feature of portable electronic devices to cut the last wire. Resonant wireless power transfer (R-WPT) using magnetic resonance emerges as a promising approach, as it provides spatial freedom and can charge multiple devices simultaneously. ISM-band frequencies such as 6.78MHz or 13.56MHz are commonly used as the resonant frequency of the LC tank [1–4]...
This paper described a synchronized output regulation (SOR) strategy for control of inverters working in grid-connected and stand-alone modes. As a concept of networked dynamic systems, SOR means that the nodes have their outputs synchronized but also demonstrate the desired wave shape. Both the inverter and the utility are regarded as two nodes of the simplest network consisting of themselves. In...
The paper presents results of research of quad-inverter-based automotive system with combined scheme of PWM control of inverters, supplied by two renewable dc sources (by fuel cells and by battery). It has been shown, that hybrid switching techniques can be used successfully for control of vehicle drive with non-equal (variable) voltages of dc-links. Results of modeling proved the fact of symmetries...
This paper presents a new DC-DC converter that is designed to provided selected polarities at desired voltage levels. With the new switching converter topology, the converter can boost and buck the input voltage and theoretically achieve infinite levels for either positive or negative polarities. This converter can provide a wide range of output voltage and use only one switch to perform the power...
The dual-mode photovoltaic inverter is capable of operating either in grid-connected mode or island mode, acting as a current source for the ac grid in the former and a voltage source for the load in the latter. Transitioning from one mode to the next is non-trivial and can cause large deviations in voltage, current, and frequency because a mismatch in frequency, phase, and amplitude between the inverter...
This paper presents a PWM strategy for the reduction of common-mode (CM) voltage generated by variable-speed motor drives composed of two-level, three-phase active-front-end rectifier and three-phase inverter. This method theoretically provides complete elimination of the CM voltage by synchronizing all inverter commutations with rectifier commutations, so that the resulting CM voltage does not vary...
The operation of micro-grid based renewable energy usually considers efficiency and economy in comprehensive. The control strategy based on master micro-source (MS) constant voltage constant frequency (CVCF) networking is introduced. The voltage and frequency of micro-grid is established by the master MS, and the slave MS operated on the maximum power point tracking mode, in order to achieved micro-grid...
This paper proposes a novel control strategy for smooth transition between stand-alone and grid-connected modes of distributed generation (DG). The proposed control scheme is designed in stationary (α-β) reference frame consisted of outer grid current control loop using a proportional resonant (PR) controller and the inner load voltage control loop developed with a repetitive controller (RC). The...
This paper proposes a novel seamless transfer method for microgrid connected fuel cell inverters (FCIs) between voltage source and current source modes. In order to protect the fuel cell, the FCI output power should be restricted when the microgrid frequency is greatly disturbed. In this sense, the FCI is transfered from voltage source mode to constant current source mode. Meanwhile, the FCI is transfered...
Recently, the demand for miniaturized and fast transient response power delivery systems has been growing in high-voltage industrial electronics applications. Gallium Nitride (GaN) FETs showing a superior figure of merit (Rds, ON X Qg) in comparison with silicon FETs [1] can enable both high-frequency and high-efficiency operation in these applications, thus making power converters smaller, faster...
Recent work has shown that monolithic integration of voltage regulators will be feasible in the near future, enabling reduced system cost and the potential for fine-grain voltage scaling (FGVS). More specifically, on-chip switched-capacitor regulators appear to offer an attractive trade-off in terms of integration complexity, power density, power efficiency, and response time. In this paper, we use...
The three-loop power virtual synchronous generator (VSG) control methods are commonly used in microgrid inverter (MGI) units to share the loads among the parallel MGI units. In order to achieve stable operation of the MGI units under paralleled or grid-connected mode, a droop synchronization controller is designed in this paper. The difference of phase and amplitude between different MGI units is...
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