Search

This paper presents a study of a new dc-dc non-isolated high gain converter called Double Zeta Quadratic Converter. From a single basic switching cell of a family of quadratic converters, the topological states, the waveforms of voltage and current, and the output characteristic graph of the converter are presented in this paper. To prove the advantages of this new topology as the high static gain and high efficiency, the raised curves are illustrated. Besides, the experimental results of the proposed converter are presented in this paper.

A reliable and precise frequency detection algorithm is useful for different control strategies, especially on microgrid and aerospace applications. The widely-linear adaptive frequency estimator is based on the Augmented Complex Least Mean Square Filter and, thus inherits its fast dynamic response. However, it presents a high susceptibility to input noise, which might present an unexpected behaviour under distorted grid conditions. Therefore, this work proposes a Delayed Signal Cancellation pre-filter stage to eliminate most of the harmonics to achieve fast estimation response and high rejection of harmonic distortions.

This work presents various multilevel converters obtained from basic dc-dc converters for high-voltage and high-power applications. Several cells are proposed, which have a single switching pattern realized via a simple modulator circuit that compares triangular carriers with a sine modulator. One of the main features of the proposed circuits is that some transistors work at low frequency and withstanding high voltages or high currents, while others are switched at high frequency and low voltage or low current levels. The topologies can be classified as hybrid. In addition, taking account that having the slow bridge as an output circuit means that a reduced number of semiconductor components leads to a relatively high number of levels.

In this paper, a single-phase unity power factor rectifier, based on a hybrid boost converter, resulting from the integration of a conventional dc–dc boost converter and a switched-capacitor voltage doubler is proposed, analysed, designed and tested. The high-power rectifier is controlled by two feedback loops with the same control strategy employed in the conventional boost-based rectifier. The main feature of the proposed rectifier is its ability to output a dc voltage larger than the double of the peak value of the input line voltage, while subjecting the power switches to half of the dc-link voltage, which contributes to reducing the cost and increasing the efficiency. Experimental data were obtained from a laboratory prototype with an input voltage of 220 Vrms, line frequency of 60 Hz, output voltage of 800 Vdc, load power of 1000 W and switching frequency of 50 kHz. The efficiency of the prototype, measured in the laboratory, was 96.5% for full load and 97% for half load.

High performance three–phase PWM rectifier topologies are mandatory in first stage of telecommunication power supplies due requirements regarding standards of EMC and power grid as well compactness and high efficiency provided. In this context two and three level topologies have been addressed in this application successfully, considering different control and modulation strategies. The paper proposes an analytical comparative analysis of current efforts at system level performance of SiC-based 15 kW three–phase PWM rectifier topologies.

This paper presents a three-phase multilevel power factor correction (PFC) rectifier employing multistate switching cells. A generalized converter structure is presented based on the connection of switching networks of Vienna-type rectifier topologies through multiinterphase transformers (MIPTs). The resulting rectifier presents the intrinsic benefits to the employed building blocks and the ones added by a modular construction that enables the reduction of passive components and overall losses. The operation of the PFC rectifier is described, including appropriate modulation and control strategies. Design guidelines for the magnetic components are derived for the MIPTs, boost inductors, and power semiconductor devices. Finally, a lab prototype is used to present experimental results. This prototype is rated at 7.5 kW and uses a modular structure to assemble a four legs per phase rectifier. Efficiency above 98% from 40% load and IEC61000-3-2 requirements are observed.

This paper presents the procedures employed to specify, design and implement a Cuk converter of 300 W, applied as an electrical characterizer of photovoltaic modules. The designed prototype is autonomous, portable and allows to transfer the measured data (voltage, current, solar irradiance and temperature) to a personal computer by RS232 serial communication. From these quantities, the I-V and P-V curves are plotted and the five parameters that describe the one diode model of the tested PV module are obtained. Thus, it is possible to replicate the photovoltaic module behavior in a simulation platform regarding any solar irradiance and temperature conditions. In order to validate the accuracy of the developed characterizer, the experimental curves obtained from it are compared with those acquired from the use of a commercial PV tracer.

This article shown an FPGA implementation on estimation of fundamental frequency of three-phase power system based on widely linear ACLMS algorithm. The frequency estimator using FPGA is proposed with a view applications in active microgrids. The main goal oh this article is to depict some practical issues that must be taken care during the algorithm implementations for reach this aim, as like: numerical representation, frequency sampling, quantization, so on. The proposed online frequency estimator is based on Clarke's transformation and widely linear complex domain modelling. The algorithm is implemented using VHDL-hardware description language, simulations and experimental results using FPGA support the analysis.

Poly-phase systems have been used for many years in machines and recently in wind power generations. They usually are built by a dual three-phase system, shifted by 30 electrical degrees from each other and with no neutral connection. Typically, this system employs a twelve-pulse diode rectifier to converter ac to dc voltages. However, it may be improved if an active rectifier is used, because it can provide lower distortion in generator currents and regulated output voltage. Taking that into account, this paper proposes a six-phase active rectifier topology for a dual three-phase system. A stationary frame reference for six-phase system is applied to obtain the converter dynamic model in the αβ coordinates and thus a control strategy is proposed in this frame reference. The proposed topology, dynamic model and control strategy were verified by simulation for following specification: 12 kW, 220 V at input voltage and 800 V at the output voltage. The results were appropriated, providing a regulated output voltage, an input current with reduced harmonic distortion and thus high power factor.

This paper presents a new nonisolated buck/boost-type multilevel dc-dc converter suitable for high-power and medium/high-voltage application. The main features of the proposed topology are as follows: low voltage across the semiconductors, low switching losses, and reduced volume of the output filter. The theoretical analysis is carried out for a five-level bidirectional structure of the proposed converter, operating in Buck mode. The proposed topology presents some capacitors, and their voltage must be balanced for proper operation of the converter. Thus, a capacitor voltage balancing active control using a feedforward technique is proposed and analyzed in detail. In order to validate the theoretical analysis, a prototype with 10 kW output power capability, 1.3 kV to 800 V input-to-output voltage, and 20 kHz of switching frequency was built and experimented. The results attest the advantages of the new dc-dc topology, as well as the new capacitor voltage control technique.

Alternating current (ac) active electronic loads (AELs) based on pulsewidth modulation (PWM) converters, capable of emulating nonlinear loads, require effective current control techniques and power stages. These two aspects of an AEL are interdependent mainly due to the presence of electromagnetic compatibility filters to reduce electromagnetic emissions. However, the filter components affect the dynamics of the system. In this context, this paper proposes a digitally implemented control strategy comprising the state feedback, robust observer, phase-locked loop, and linear current controller to cope with ac AEL applications. The control-oriented modeling and the control system design are presented. Experimental results obtained from a 10-kW three-phase three-level PWM converter prototype illustrate and demonstrate the feasibility of the proposed AEL control strategy.

Novel simple indirect control concepts for an active power filter (APF) application are proposed here. The concepts are exemplarily presented to control a modified APF structure. The main advantage over other control strategies is the achieved excellent simplicity-to-performance ratio. The proposed control strategies are based on the concept of virtual impedance emulation to provide high power factor in a system. To validate the operating principle, a single-phase low-power prototype has been built and experimentally tested. This prototype operates at a remarkably low switching frequency of 5 kHz and is digitally controlled by a digital signal processor.

This paper proposes a unidirectional step-up rectifier family with high voltage gain. The converters are based on the integration between traditional rectifiers and voltage multiplier switched-capacitor cell. The novel structures are referred to as hybrid boost rectifiers and they provide high gain with low voltage stress on the switches and with low gain in boost stage, which are advantages regarding to design and control. Three new topologies are introduced in this paper, two are bridgeless rectifier, and principle of operation, steady state analysis, dynamic models and simulation results are presented. All topologies provide high power factor in input current and a regulated output voltage.

The analysis DC-DC Double Quadratic Buck Converter is presented in this paper. This converter has the advantages of high static gain compared to the conventional Buck Converter. The topological symmetry reduce the stress voltage over the switches to half of the value compared with the conventional Quadratic Buck Converter and simplifies the modeling of the converter. The analysis is made for continuous, critical and discontinuous conduction mode and boundary curve between the conduction modes is shown. Finally, the simulation and experimental results are presented to prove the theoretical analysis.

Poly-phase systems have been used for many years in machines and recently in wind power generations. Typically, this system employs diode rectifiers, however, it may be improved employing active rectifier. Considering it, this paper proposes a six-phase active rectifier topology controlled in synchronous frame reference. Results were validated by simulation.

The single-phase multilevel power-factor correction rectifier employing multistate switching cells is analyzed regarding different operational aspects. The generalization of the number of switching states is performed in order to clarify issues such as the input current ripple, the output currents rms values, power semiconductor stresses, and others. A discussion on the optimal number of switching states is carried out, based on the generated models. In this context, this work is a first step aiming in the efficiency-based optimization of the concept.

Novel symmetric hybrid multilevel topologies are introduced for both single- and three-phase medium-voltage high-power systems. The topology conception is presented in detail, where a three-level switching cell with low component count, and its modulation pattern give the origin of the proposed converters. Voltage sharing and low output-voltage distortion are achieved. The theoretical frequency spectra are derived. Switching devices are separated into high- and low-frequency devices, generating hybrid converters. Five-level three-phase topologies are generated from only three insulated dc sources, while the number of semiconductors is the same as for the cascaded H bridge. Both simulation and experimental results are provided showing the validity of the analysis.

Almost two decades of research on unidirectional three-phase multilevel boost-type pulsewidth modulation (PWM) rectifiers have shown the benefits of employing this technology to comply with power quality standards while assuring high efficiency and low volume and weight. However, the unidirectional topologies directly derived from the conventional three-level bidirectional converters, such as the neutral point clamped (NPC), the flying capacitor and the cascaded H-bridge converters have not been properly analyzed. This letter introduces some of the unidirectional topologies that arise from the inspection of the widespread conventional bidirectional converters. Special emphasis is put in the analysis of the NPC-based three-phase/-level PWM rectifier operating as power factor corrector.

This paper presents the T-Type Zero Voltage Switching Pulse Width Modulated isolated DC-DC converter (TT-ZVS-PWM Converter). The proposed topology is composed of four switches. Two of these are subjected to the input voltage and the other two to half the input voltage. All switches commutate under zero-voltage. The proposed converter has the following in common with the Full Bridge Zero-Voltage Switching (FB-ZVS-PWM) and the Three-Level Zero-Voltage Switching (TL-ZVS-PWM) converters: (a) symmetrical operation of the isolation transformer, (b) modulation by pulse-width with constant frequency, (c) zero voltage switching, and (d) three-level voltage applied to the primary winding of the transformer. Theoretical analysis, design example and experimental data for a 3 kW, 400 VDC input, 60 VDC output, and 50 kHz switching frequency laboratory prototype, are included in the paper. Measured efficiency was 93% at full load and 95.2% at 1.2 kW.

Multilevel multistate switching cell-based rectifiers have been presented as interesting alternatives for modern power electronics applications. Due to their modular nature, it is possible to build such converters with various semiconductor legs, which results in different performance levels, assembly complexity and cost. This paper presents a theoretical evaluation of how the number of legs influences the semiconductor losses in two particular situations, where switching frequency and apparent frequency are paramount parameters in the design. Experimental results of a 1.5-kW single-phase multilevel multistate switching cell-based rectifier with two semiconductor legs are presented.

It is presented the study and simulation of a novel hybrids matrix converters (HMC) based on the Cuk AC-AC converter [17], mainly focused on residential wind power applications where the input voltage presents great variability in amplitude and frequency. The main feature of these circuits is their wide input voltage range, operating with a gain greater than unity. Furthermore, due to its hybrid feature, energy storage elements present low values. As a result, a voltage gain greater than unity is achieved, which is the main limitation of the current matrix converters (MC). Theoretical expressions shown through digital simulations on PSIM environment are validated.

The design expressions of an indirect matrix converter (IMC) and a Δ-Switch IMC are discussed in this work based on the specifications of a 10 kW motor drive system with 1.2 kV SiC power semiconductor devices. The conduction and switching losses models for both topologies are presented to be used in the dimensioning. The ΔIMC leads to a peak efficiency of 97.7% at a switching frequency of 20 kHz with power density of 2.88 kW/dm3.