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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...
Neutral point potential oscillation at low frequency is an important issue in four pole neutral point clamped converter since this leads to the extra voltage stress on the split DC-link capacitors. The detailed analysis indicates such oscillation is closely associated with the neutral point current at low frequency, so this paper explores their relationship, and presents the modulation techniques...
This paper proposes a single-phase ac-dc-ac converter composed of two three-leg converters connected in series with an H-bridge on its grid side. The proposed converter allows to feed the load voltage with sinusoidal voltages with constant amplitude and frequency and to operate with sinusoidal grid current with high power factor. Besides, the converter can be used to mitigate fundamental overvoltage...
This paper presents the design of a digital controller for a 600 W Boundary-Conduction-Mode (BCM) interleaved boost converter used in an ac-dc Power-Factor-Correction (PFC) power supply. The output voltage of a typical boost PFC rectifier contains a 2nd harmonic ripple. Therefore to achieve good power factor, the output voltage compensator must have a low bandwidth, in order to sufficiently attenuate...
The paper deals with a high efficiency boost rectifier for high rotational speed Gen-Set applications. It is tailored around a permanent magnet synchronous generator (PMSG) featuring an open end winding configuration. According to such a configuration the generator stator windings are connected on one side to a three level T-type unidirectional rectifier, and on the other side, to an auxiliary two-level...
A well-known problem of three-level neutral point clamped (NPC) inverter is the voltage imbalance in the dc-link capacitors. This paper proposes the dc-link capacitor voltage balancing method where a common offset voltage is injected. The offset voltage consists of a harmonic voltage and a magnitude difference between the upper and the lower capacitors. Theoretical analysis is provided to balance...
This paper presents a case study of different control approaches for a single phase Dual Active Bridge (DAB) based MVDC Shipboard power system (SPS). The Line Regulating Converters (LRCs) are based on DAB topology and the load side converters or Point of Load Converters (POLs) are based on buck topology. The tightly controlled POLs exhibit a constant power load (CPL) behaviour, which has a destabilising...
AC-DC single-stage converters are widely used in industrial applications because they are cheaper than conventional two-stage converters. In this paper, state of the art low power single-stage converters are reviewed. These converters are classified into several types in the paper, the operation of an example converter of each type is discussed, and the advantages and drawbacks of each type are stated...
A simple on-line auto-tuning technique for a resonant converter to achieve output voltage regulation while tuning the switching frequency to the resonant frequency is proposed in this paper. The proposed method can deal with resonant frequency variation caused by the resonant components tolerance and variation. The proposed technique is developed by detecting the zero-crossing point and peak point...
Although the mechanism of electric energy flow for nonsinusoidal conditions is well described today, so fare is not yet available a generalized power theory, and theoretical calculations for the design of such devices as active filters or dynamic compensators. Therefore the task of designing compensators for optimize energy transmission with nonlinear time-varying loads in nonsinusoidal regimes is,...
This paper presents a boost switched-capacitor nine-level single-phase inverter, which utilizes flying capacitors and an H-bridge. Besides the boosting ability, the inverter is capable of producing redundant switching states that are used as a degree of freedom in controlling the voltage of DC link capacitor. A comprehensive study of the theoretical aspects of the proposed structure and its practical...
The article is devoted to the electromagnetic compatibility (EMC) tests of the 10/0.4 kV transformer-thyristor regulator (TTR) which has been developed by Nizhny Novgorod Technical University. The research subject was medium (6–20kV) and low (0.4 kV) voltage power distribution network (PDN). The medium and low PDN computer simulation models are described. These models allowed us to estimate of the...
With the development of more/all electric aircrafts, variable frequency AC (VFAC) generation systems become popular. Dual stator-winding induction generators (DWIG) utilized in VFAC systems have the feature of the high fundamental frequency. However, the switching frequency of high power devices does not exceed 5 kHz in general, which makes carrier ratio lower. Thus, how to ensure the quality of the...
Ordinary single phase inverter gives a square wave output which when applied to electrical appliances may damage the later, reduce its efficiency as well as life as this inverter output waveform is not sinusoidal and contains lower and higher order harmonics in addition to fundamental. Moreover, the output voltage cannot be controlled. In this paper a single phase half bridge inverter is discussed...
In this paper a full-bridge phase-shift DC-DC converter that has the function of realizing zero-voltage switching (ZVS) is adopted into power electronic transformer (PET), and the functions of every part employing proper control strategy in the PET are analyzed. The simulation results show that this converter can still realize soft-switching in PET and it is appropriate to work in high frequency state...
In this paper, a novel adaptive delta modulation (ADM) control scheme is proposed as a driver for an interleaved DC/DC power converter, analysis of the converter is carried out in order to achieve the required system stability and to improve the dynamic performance. The output response characteristics obtained by this method is very much improved compared to the conventional methods. The proposed...
Power factor and harmonics are primary factors in electrical distribution network. Harmonics are generated by the non-linear and irregular loads at end users. High harmonics in devices draws the large amount of current which results in poor power factor. Hysteresis control technique is one of the techniques in power factor converter topologies. Switching losses, low power factor and high harmonic...
In this paper, the performance of a Single DSTATCOM is evaluated for the purpose of harmonics elimination, reactive power compensation and load balancing. A control scheme has been proposed for DSTATCOM and its characteristics are investigated by digital simulation. A current controller on the single-phase basis forms the innermost loop in the control hierarchy. The dc bus voltage controller and PCC...
This paper presents a procedure that works at fundamental frequency to compute switching angles in single phase 9-level converters to eliminate the third and odd triple harmonics and to reduce other low order harmonics, obtaining a low total harmonic distortion (THD). The DC voltages feeding the converter, that are equal, but variable, allow to obtain switching angles independent on modulation index...
One of the commonly used approaches to avoid the short circuit of power devices for pulse-width-modulation (PWM) inverters is to add dead-time into the control signals. The drawback of this approach is that severe distortion in phase currents and output voltages may occur. This paper proposes an adaptive-linear-neuron based nonlinearity compensation strategy to cope with the disturbance voltage caused...
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