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Power Electronics Conference, 2009. COBEP '09. Brazilian

Date Sept. 27 2009-Oct. 1 2009

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Displaying Results 1 - 25 of 175
  • A power control scheme for doubly-fed induction generator

    Page(s): 1141 - 1148
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1344 KB) |  | HTML iconHTML  

    This paper proposes a power control scheme for doubly-fed induction generator for variable speed wind power generation. This scheme uses stator flux decoupling and deadbeat control loops. The algorithm of the deadbeat calculates the voltage vector to be supplied to the rotor in order to guarantee that the active and reactive power reach their desired reference values. Because the generator leakage inductance and resistance information were required for this control method, the influence of the estimation errors for these parameters was also investigated. Simulations results are carried out for validation of the digital controller operation. View full abstract»

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  • A soft-switching universal-input voltage HPF rectifier implemented with a modified sepic converter

    Page(s): 948 - 955
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (850 KB) |  | HTML iconHTML  

    A high-power-factor rectifier suitable for universal-line base on a modified version of the SEPIC converter is presented in this paper. The voltage multiplier technique is applied to the classical SEPIC circuit obtaining new operation characteristics as low switch voltage operation and high static gain at low line voltage. The new configuration also allows the reduction of the losses associated to the diode reverse recovery current and soft-commutation is obtained with a simple regenerative snubber circuit. The operation analysis, design procedure and experimental results obtained from a 650 W universal-line high power factor prototype of the proposed converter are presented. The theoretical analysis and experimental results obtained with the proposed structure are compared with the classical boost topology. View full abstract»

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  • Storage energy management with power quality concerns the analytic hierarchy process and the fuzzy logic

    Page(s): 225 - 231
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (565 KB) |  | HTML iconHTML  

    In view of current and foreseeable energy shortage and environmental scenario, the exploitation of renewable energy sources offer great potential to satisfy the energy lack and to decrease the dependence on fossil fuel, also reducing global warming caused by CO2 emissions. However, widespread implementation of these sources will be more attractive only if they operate together with energy storage technologies. Besides, an effective storage energy management is essential to deal with some mismatches among power quality, efficiency, costs and environmental constrains. This paper presents a methodology taking as basis the analytic hierarchy process and fuzzy multi-rules and multi-sets. By exploiting a multi-criteria decision making, this methodology evaluates the operation of energy storage systems such as: pumped hydro storage (PHS), compressed air energy storage (CAES), H2 storage, flywheel, super-capacitors, lithium-ion and NaS advanced batteries and VRB flow battery. The main objective of the study is to develop a multicriteria analysis to find the most appropriate energy storage system concerning a power quality priority. For this, the criteria in analysis are: efficiency, load management, technical maturity, costs, environment impacts and power quality. Considerations and results described in this paper are part of the Research & Development Program undertaken by the Federal University of Santa Maria, Brazil. View full abstract»

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  • The complex controller applied to the induciton motor stator flux orientation control

    Page(s): 130 - 137
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (579 KB) |  | HTML iconHTML  

    This work proposes a design and tuning method for a complex gain, based on the three-phase induction motor mathematical model complex transfer function to be used in induction motor control at low speed which is a problem so far. The complex gain controller was applied on stator field orientation control and it was designed and tuned by frequency-response function of the closed loop system. The complex gain controller has a minor complexity to the induction motor control implementation. The stator flux orientation control means a current control by using stator flux orientation and direct torque control. Experimental results are carried out to validation of the controller. View full abstract»

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  • A low cost single-phase grid-connected photovoltaic system with reduced complexity

    Page(s): 1033 - 1038
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1045 KB) |  | HTML iconHTML  

    This paper presents a grid-connected photovoltaic (PV) system using the classical DC-DC buck converter, which is responsible for stepping down the resulting voltage from several series-connected panels. Besides, the buck converter provides sinusoidal current injected into the utility grid, which is possible by using hysteresis modulation. A CSI inverter employing thyristors is cascaded with the DC-DC stage so that AC voltage results. The inverter output voltage level is adjusted by using a low frequency transformer, which also provides galvanic isolation. Low cost, simplicity, and reduced harmonic content of the injected current are direct advantages of the proposed system, which is designed and analyzed by simulation. An experimental prototype is also implemented, as relevant results are presented and discussed. View full abstract»

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  • Generated voltage control of the SRM operating as motor/generator

    Page(s): 830 - 835
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (960 KB) |  | HTML iconHTML  

    This article treats the switched reluctance motor/generator drive for general purpose. A typical half-bridge converter topology is used to attain the motor operation mode. Although, the converter topology is strategically modified to make possible the generator operation mode. It is achieved automatically through a relay and so the phase demagnetization generates power to the load. Also the switching angles control must be simultaneously provided. Three techniques are proposed here to control the load voltage when the machine is operating as a generator. All of them exert control on the machine magnetization level. Some simulated results are presented here to show that the proposed techniques are capable of been dealt with successfully. It is showing the applicability of the switched reluctance machine as a motor/generator device. View full abstract»

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  • A teaching method applied in the power electronics laboratory

    Page(s): 1082 - 1087
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (993 KB) |  | HTML iconHTML  

    The use of power electronics-based equipment has been steadily increasing in industrial and consumer applications, leading professional training in the field to be increasingly predicated on economic growth, and resulting in the motivation of electrical engineering students which choose this discipline. This paper presents a teaching and problem-based learning experience in power electronics, as well as a proposal and experimental project developed by student groups. View full abstract»

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  • Grid-connected PV system using a three-phase modified dual-stage inverter

    Page(s): 167 - 173
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2129 KB) |  | HTML iconHTML  

    This paper presents a PV grid-connected system in centralized configuration and constructed with a three-phase dual-stage inverter. In this topology, usually, a DC-DC converter performs the maximum power point tracking (MPPT) and an inverter is responsible for controlling the grid-current. For the DC-DC stage the three-phase series resonant converter (SRC3) is chosen thanks to the advantages that it exhibits. However, it is inadequate for the accomplishment of MPPT, due to its efficiency strongly depending on the implemented deadtime and switching frequency. Then, this paper proposes a conceptual modification, i.e., a dual-stage inverter in which the inverter stage is responsible for the MPPT and the grid-current control. In addition, the DC-DC converter operates with constant duty cycle and frequency. Such configuration requires a new concept, introduced as Behavior Matching. It serves as a fundamental feature for the DC-DC converter to reproduce the PV array I-V characteristic when they are connected, without control action. The maximum power operating point (MPOP) is found by maximizing the direct axis current, obtained by Park's transformation from the inverter, through the perturbation and observation algorithm (P&O). Any specific measurement to realize MPPT is not needed. The galvanic isolation is achieved by using a high-frequency transformer. The structure is appropriate for high power applications, above 10 kW. View full abstract»

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  • Static and dynamic measurements in small induction motors using a fiber Bragg grating interrogation unit

    Page(s): 1113 - 1117
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (605 KB) |  | HTML iconHTML  

    This paper describes the implementation of an interrogation system using optical fiber sensors, specifically fiber Bragg gratings, to be used in the evaluation of the thermal performance of an induction motor. It is shown that the system can also operate as a strain monitoring system which suggests that it can equivalently be used to measure strain inside the motor. The main component in the system is an optical integrated device, manufactured by Santec (OWL-10-WT). It operates as a transducer of optical signals. The interrogation principle is based on an intensity-based signal associated with the measurand. The interrogation unit also shows a low cost if compared to other similar systems. View full abstract»

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  • Power transference to AC voltage sources

    Page(s): 1000 - 1005
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (593 KB) |  | HTML iconHTML  

    This paper presents a simple approach of a topology already known in the literature, applied in active power transference from DC source to any AC voltage source, whether the utility power or a voltage inverter that is forming an isolated AC grid. Simulation results of this application are presented and experimental results validate this topology. View full abstract»

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  • Boost based on three-state switching cell for UPS applications

    Page(s): 313 - 318
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1800 KB) |  | HTML iconHTML  

    This paper presents a novel boost topology based on three-state switching cells for uninterruptible power supplies (UPS) applications. The main features of this converter are: reduced conduction losses on the controlled switches, magnetic components operating with the double of switching frequency reducing weight and volume, reduced high-frequency current ripple, simple control strategy that can be implemented with well know integrated circuits and connection between input power supply and converter output enabling the use of UPS inverter and by-pass. A theoretical analysis and experimental results from a 3 kW lab model are presented. View full abstract»

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  • Non-isolated DC-DC converters with wide conversion range used to drive high-brightness LEDs

    Page(s): 598 - 605
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (647 KB) |  | HTML iconHTML  

    Light emitting diodes (LEDs) have many features that make them attractive for use in an increasing number of applications. Particularly in lighting, the small size of LEDs compared to fluorescent and incandescent bulbs is a prominent advantage. This paper presents two topologies based on the buck converter, which have higher step-down characteristic than that of the original converter. The quadratic buck converter is studied and used to drive series-connected LEDs. Improved characteristics if compared with the traditional converter include the continuous current maintained through the LEDS and the possibility of driving several types of LED arrays. The study is then extended to the cubic buck converter, as a novel arrangement to obtain the mentioned step-down characteristic is introduced in this work. The use of such converter allows obtaining lower output voltages than those resulting from the quadratic buck converter. Experimental prototypes of the converters are implemented and fully tested. It must be also mentioned that a PIC microcontroller is used to control the current through the LED array, what provides robustness and flexibility in the adjust of the control algorithm without the need of hardware modification. View full abstract»

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  • Analysis and simulationof the P&O MPPT algorithm using alinearized PV array model

    Page(s): 189 - 195
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (509 KB) |  | HTML iconHTML  

    This paper shows that the performance of the perturb and observe (P&O) maximum power point tracking (MPPT) algorithm is improved when the electronic converter is correctly controlled. A linearized photovoltaic (PV) array model is used to obtain the transfer function of the electronic converter and to design a voltage compensator for the converter input voltage. A buck converter is used in this work. View full abstract»

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  • Three-phase multi-level DC-AC converter using three-phase, coupled inductors

    Page(s): 332 - 339
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1135 KB) |  | HTML iconHTML  

    A new three-phase multi-level DC-AC converter with three-phase coupled inductors is presented in this work. The related converter is employed only as an inverter here. Initially the power stage diagram and the modulator are shown and discussed. Their main characteristics are described and the more relevant waveforms, generated by simulation, are shown. Next, the operation of the converter with sinusoidal PWM modulation is discussed and some relevant figures are presented. The vectorial interpretation of the line load voltage is shown to all available vectors of load voltage in the new structure. Finally, experimental results obtained from the implemented prototype are presented and briefly discussed. View full abstract»

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  • High frequency isolation pre-regulator with power factor correction applied to UPS using self-control technique on a DSPIC

    Page(s): 635 - 640
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (787 KB) |  | HTML iconHTML  

    This paper presents the project and the implementation of a high frequency isolation pre-regulator for applications in UPS systems using an easy implementation control technique, which uses fewer sensors and has good performance (>90%), named self-control. The technique was carried out using a DSPIC from MICROCHIP. A 1 kW prototype was assembled and its experimental waveforms will be presented on this paper. View full abstract»

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  • A novel three-phase three-level ZVS PWM DC-DC converter

    Page(s): 916 - 924
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (2826 KB) |  | HTML iconHTML  

    A novel three-phase DC-DC converter based on the three-phase neutral point clamped (NPC) commutation cell is proposed. A static analysis is made for a particular mode of operation, allowing the development of a design procedure for the power stage. The small-signal analysis based on the phasor transformation is also proposed, providing fundamental knowledge for a satisfactory compensation in closed-loop operation. From the theoretical analysis carried out, a design procedure is elaborated, providing the values of all power stage components. Finally, the simulation of a 10 kW TPTL-PWM converter is performed to validate all theoretical considerations made in the paper. View full abstract»

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  • A novel single-phase HPF hybrid rectifier suitable for front-end trolleybus systems

    Page(s): 619 - 626
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (945 KB) |  | HTML iconHTML  

    This paper proposal presents the development and the experimental analysis of a new single-phase hybrid rectifier structure with high power factor (PF) and low harmonic distortion of current (THDI), suitable for application in traction systems of electrical vehicles pulled by electrical motors (trolleybus), which are powered by urban distribution network. This front-end rectifier structure is capable of providing significant improvements in trolleybuses systems and in the urban distribution network costs, and efficiency. The proposed structure is composed by an ordinary single-phase diode rectifier with parallel connection of a switched converter. It is outlined that the switched converter is capable of composing the input line current waveform assuring high power factor (HPF) and low THDI, as well as ordinary front-end converter. However, the power rating of the switched converter is about 34% of the total output power, assuring robustness and reliability. Therefore, the proposed structure was named single-phase HPF hybrid rectifier. A prototype rated at 15 kW was developed and analyzed in laboratory. It was found that the input line current harmonic spectrum is in accordance with the harmonic limits imposed by IEC61000-3-4. The principle of operation, the mathematical analysis, the PWM control strategy, and experimental results of a 15 kW prototype are also presented in this paper. View full abstract»

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  • Robust PSC control design for sinusoidal tracking in uninterruptible power supplies

    Page(s): 389 - 396
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (642 KB) |  | HTML iconHTML  

    This paper proposes an alternative strategy to track sinusoidal reference signals with zero steady state error for uninterruptible power supplies - UPS. A robust proportional-sinusoidal-cosinusoidal (or in short PSC) controller is derived for sinusoidal voltage regulation subject to load variations. The controller parameters are determined by means of a convex optimization problem subject to a set of linear matrix inequalities (LMIs). Simulations and practical experiments demonstrate the potential of the proposed approach for controlling UPS systems. View full abstract»

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  • Performance analysis of a neural flux observer for a bearingless induction machine with divided windings

    Page(s): 498 - 504
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1677 KB) |  | HTML iconHTML  

    This study presents a performance analysis of a neural observer applied to speed and radial position controls of an induction-type bearingless motor with divided windings. The speed and radial control actions are carried out in conjunction with current control in the windings. The neural flux observer aims at compensating possible parametric variations of the machine caused by agents such as temperature or nucleus saturation. Control and estimation of flux are executed by a program developed in ANSI C language. The following resources were used in the DSP: the analog/digital converter, the PWM outputs and the RS-232 parallel and serial interfaces, which are responsible, respectively, for programming the DSP and capturing data using the supervisory system. Compared with a fixed parameter, the observer validates the proposed method. View full abstract»

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  • Design and implementation of a digital control system for an axial flux switched reluctance motor

    Page(s): 138 - 144
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (691 KB) |  | HTML iconHTML  

    Nowadays, besides the rapid growth of different areas like the mechanical and electrical ones, it is possible to identify a particular effort to develop new motors including new electrical drives and control systems. Additionally, these equipments are being designed to give them the maximum efficiency as the energy cost is continuously increasing. With this in mind, some results related to a particular switched reluctance motor, are presented. The airgap between its poles are distributed in such a way that they are parallel to the rotation axis. Such structure is little studied by researchers. On the other hand, in order to maintain a low ripple torque, a particular algorithm is proposed which consists in imposing motor currents with a special format. The implementation of this strategy was made using two microcontrollers, one to determine the position and speed of the rotor while the second impose the appropriated current to the motor windings. This strategy has been successfully tested to control the speed of the rotor in a simple feedback loop. View full abstract»

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  • Operating points of a doubly fed cascaded induction machine

    Page(s): 124 - 129
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (839 KB) |  | HTML iconHTML  

    This paper will describe the operating possibilities of a doubly fed cascaded induction machine. Some of the advantages of this system, for example, the controllable synchronous speed operation over a limited speed range and the reduced power converter rating, will be highlighted and explored with computer simulations. View full abstract»

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  • A Python based power electronics E-learning tool

    Page(s): 1088 - 1092
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1180 KB) |  | HTML iconHTML  

    Simulation became an integral part of power electronics and electrical drives learning process. This paper presents a collection of software programs that can be useful in the teaching process of power electronics and electrical drives. This tool is developed with Python language and libraries, which can be freely distributed. Without going through complicated mathematics and software manuals, students can obtain steady state waveforms from power electronics circuits, their mean and RMS values, as well as spectra. Electrical machine principles are also shown, using animation tools. View full abstract»

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  • A single-phase UPS system with harmonic suppression and reactive power compensation

    Page(s): 558 - 563
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1159 KB) |  | HTML iconHTML  

    This work proposes a control strategy applied to a single-phase uninterruptible power supply (UPS) system with series-parallel active power-line conditioning capabilities, allowing sinusoidal input current and sinusoidal output voltage, which results in an effective power factor correction. The UPS system is composed by two single-phase PWM converters in order to perform the active power line filter functions. The series converter acts as a series active power filter, which works as a sinusoidal current source in phase with the input voltage. The parallel converter acts as a parallel active power filter, which works as a sinusoidal voltage source in phase with the input voltage, providing sinusoidal voltage with low total harmonic distortion (THD). The detection of the angle-phase is performed using a single-phase PLL (phase-locked loop) structure, which is based on instantaneous active power theory. The PLL system has been implemented into two-phase stationary reference frame. Thereby, a fictitious quadrature voltage needs to be generated, which must be orthogonal to the measured utility voltage. Both the control algorithm of the UPS system, which uses synchronous reference frame (SRF) method, and the active power flow that occurs through the UPS system will be described and analytically studied. Mathematical analysis of the SRF-based algorithm is presented and simulation results are performed to validate the theoretical development and to verify the performance of the UPS system. View full abstract»

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  • Double conversion uninterrupted power system with integration of the rectifier and the inverter

    Page(s): 551 - 557
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (708 KB) |  | HTML iconHTML  

    This paper presents a novel topology for double conversion uninterrupted power supply (UPS). The most important characteristics of this converter are: low cost, low conduction and commutation losses on all the controlled switches, the control is implemented with commercial integrated circuits, and the rectifier and the inverter are on the same circuit. Theoretical analysis, operation principle, and topology details are presented and validated through experimental results. View full abstract»

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  • Voltage regulation and balance dynamic control in 15 kV — Electric distribution networks

    Page(s): 232 - 239
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1142 KB) |  | HTML iconHTML  

    This work presents an analysis of a distribution static compensator (DSTATCOM) as a substitute or a complement to the classical voltage regulation and balancing techniques, highlighting each alternative characteristic, advantages and disadvantages, considering the parameters of an actual 13.8 kV distribution circuit. These studies were performed focusing on a utility company investment alternatives among the technical solutions available to mitigate, avoid or postpone expenses, in order to comply with the legal principle of a prudent and necessary investment to reach the lowest possible energy tariff. View full abstract»

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