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Power Electronics, IEEE Transactions on

Issue 3 • Date May 1999

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Displaying Results 1 - 22 of 22
  • A methodology for true comparison of analytical and measured frequency domain spectra in random PWM converters

    Publication Year: 1999 , Page(s): 578 - 586
    Cited by:  Papers (39)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (192 KB)  

    The analysis of random pulsewidth modulation (PWM) techniques has matured into a state where analytical expressions have been derived to aid in understanding the frequency domain characteristics. Derivations of the formulae require a lot of algebra, and the expressions must be verified by laboratory measurements. It is shown, however, that factors originating from digital signal processing techniques make the comparison difficult if proper measures against misinterpretation are not taken. A methodology to overcome the problems is presented. Novel expressions for the random lead-lag pulse position technique and the random switching frequency technique are also presented as well as their verifications by laboratory measurements on a full-bridge DC/DC power converter View full abstract»

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  • Improved digital current control methods in switched reluctance motor drives

    Publication Year: 1999 , Page(s): 563 - 572
    Cited by:  Papers (47)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (212 KB)  

    This paper proposes a method to avoid current feedback filters in fast digital-based current loops in switched reluctance drives. Symmetrical pulsewidth modulation (PWM) and synchronized sampling of the phase current allow a noise-free current sampling with no antialiasing filter. This paper also proposes more efficient methods to chop the two transistors in the asymmetric inverter used with switched reluctance drives. A fast field-programmable gate array (FPGA)-based test system is used for validation of the new methods. Test results show a significant improvement in dynamic and steady-state current loop control compared with traditional methods. The new chopping method is found to reduce the switching losses and increase the drive efficiency View full abstract»

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  • Analysis of the self-oscillating series resonant inverter for electronic ballasts

    Publication Year: 1999 , Page(s): 533 - 540
    Cited by:  Papers (26)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (212 KB)  

    In this paper, we examine the self-oscillating series resonant inverter for electronic ballast applications from a system point of view. By considering the discharge lamp as a linear resistor in steady state, we derive a time-domain closed-form expression of the circuit state variables. Importantly, we observe that the self-oscillating series resonant inverter with lamp loads can be naturally modeled as a relay system. Based on this formulation, the self-oscillating frequencies of the inverter for variable lamp impedance conditions are found via the Tsypkin's locus. The stability of the self-oscillating frequencies is determined in a sampled-data system framework View full abstract»

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  • Three-phase series VAr compensation based on a voltage-controlled current source inverter with supplemental modulation index control

    Publication Year: 1999 , Page(s): 587 - 598
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (292 KB)  

    Shunt-type static VAr compensators have been shown to be an effective means of increasing the transmission capability of power systems and of increasing the power factor of industrial loads. This paper presents an alternative to the shunt connection consisting of a series-connected transformer-coupled pulsewidth modulation (PWM) inverter. The scheme consists of a current source inverter (CSI) fed from a self-controlled DC current bus and presents the following features: (1) instantaneous series injected voltage control through online PWM of the DC link current; and (2) steady-state modulation index of the PWM pattern near unity through DC link current minimization. The first feature results in fast dynamic response, while the second feature ensures low and fixed injected voltage harmonic distortion and reduced steady-state compensator losses. Operation of the compensator and of the two-loop control scheme are presented. Simulation and experimental results on a 2 kVA laboratory prototype unit confirm the feasibility of the proposed VAr compensator structure View full abstract»

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  • Analysis of a new high-efficiency DC-to-AC inverter

    Publication Year: 1999 , Page(s): 454 - 460
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (152 KB)  

    A high-efficiency DC-to-AC inverter for stand-alone and direct AC mains connection is described. This structure uses only off-line switches to generate the AC voltage. Due to safety reasons, the input voltage (e.g., the voltage of solar cells or batteries) is limited. Therefore, high currents on the primary side are necessary to obtain the required output power. The overall efficiency of the inverter depends to a high degree on the number of switching elements in the current path. The structure described here has only one active switch in the main path. This can be obtained by applying a diode with controlled turn-off capability (like a thyristor or other derivatives). High duty cycles (d near one) of the main switch at high currents lead to low duty cycles (1-d near zero) of the switchable diode. For that reason, a series connection of two active switches in the main path has to be avoided. The new inverter leads to improved efficiency and is therefore well suited for solar and renewable energy as well as for aerospace applications. The improvement of the efficiency is due to the new topology and not due to overdimensioning of the semiconductors. Hence, an additional potential of efficiency improvement is still available View full abstract»

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  • Analytical and experimental approach to high-frequency transformer simulation

    Publication Year: 1999 , Page(s): 415 - 421
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (148 KB)  

    This paper reports on an experimental and theoretical work about simulation of high-frequency power transformers used in switched-mode power supplies (SMPSs). The primary scope of this activity is to characterize a comprehensive transformer model for use in the final stages of the design process of an SMPS when an accurate study of the switching waveforms is an important requisite. The model should allow the designer to compare different core and winding arrangements without needing massive breadbording. Comparison between simulations and experimental results allowed improvements to be made to a transformer model developed and presented in a previous paper. This paper also investigates the real benefits of using a complex model in place of a simpler one, weighting them up against the unavoidable increase in central processing unit (CPU) time. Then simulations using a simplified model are presented, and the pros and cons are analyzed View full abstract»

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  • An analysis of three-phase low-harmonic rectifiers applying the third-harmonic current injection

    Publication Year: 1999 , Page(s): 397 - 407
    Cited by:  Papers (49)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (256 KB)  

    An analysis of the three-phase low-harmonic rectifiers applying passive third-harmonic current injection networks is presented in this paper. Optimal amplitude of the injected current to minimize the input current total-harmonic distortion (THD) is derived as a function of the injected current phase displacement. Power aspects of the third-harmonic current injection are analyzed, and it is shown that improvement in the input current THD could be obtained at the expense of the power taken by the current injection network. In the case of optimal current injection, the power taken by the current injection network is shown to be equal to 8.571% of the input power, resulting in the input current THD of 5.125%. Effects of unwanted higher order harmonics in the injected currents are studied for two previously proposed passive current injection networks. The current injection networks are compared under the constraint that volt-ampere ratings of applied components are the same. Analytically obtained results are experimentally verified View full abstract»

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  • Experimental comparison of motor bearing currents with PWM hard and soft-switched voltage-source inverters

    Publication Year: 1999 , Page(s): 552 - 562
    Cited by:  Papers (16)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (336 KB)  

    This paper compares motor bearing currents due to pulsewidth modulation (PWM) hard- and soft-switched inverters. The mechanisms for bearing currents are first identified using an approach based on direct small-signal excitation of the motor bearing with sinusoidal and square-wave signals to characterize the bearings. It is shown that many of the motor models that have been proposed in the literature to explain bearing currents do not adequately explain the observed higher frequency effects. The paper also outlines some of the important phenomena which need to be considered for a more complete description of bearing currents. Finally, the paper compares the performance of hard and soft-switched inverters with respect to bearing currents and shaft voltage. Experimental results are provided for PWM hard- and soft-switched insulated gate bipolar transistor (IGBT) inverters which have exactly the same power circuit layout, identical chassis, and rating of 70 kVA View full abstract»

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  • A high-performance ZVS full-bridge DC-DC 0-50-V/0-10-A power supply with phase-shift control

    Publication Year: 1999 , Page(s): 495 - 505
    Cited by:  Papers (22)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (400 KB)  

    This paper presents a high-performance DC-DC switching mode power supply designed to deliver a regulated 0-50 V/0-10 A output. The proposed power supply is based on a modified version of the zero-voltage switching (ZVS) full-bridge (FB) phase-shift DC-DC converter, which incorporates commutation auxiliary inductors to provide ZVS for the entire load range as well as a commutation aid circuit to clamp the output diode voltage. The control strategy is based on two control loops operating in cascade mode. The inner loop maintains a regulated output current, whereas the external voltage loop regulates the output voltage, independently of load and input-voltage changes. In order to obtain a high-reliability converter, the control circuit has been implemented using just two integrated circuits (ICs). The phase-shift regulator UC3875 IC generates the gate drive signal to the MOSFET's. The control loop regulators are implemented using the TL074 IC. A theoretical analysis was conducted, and experimental results were obtained for a 0-50 V/0-10 A power supply operating at 100 kHz View full abstract»

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  • A sliding mode current control scheme for PWM brushless DC motor drives

    Publication Year: 1999 , Page(s): 541 - 551
    Cited by:  Papers (22)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (232 KB)  

    This paper proposes a sliding mode current control scheme for pulsewidth modulation (PWM) brushless DC motor drives. An improved “equivalent control” method is used in this scheme. A simple algorithm is proposed that differs from the original equivalent control method, which requires extensive calculation to estimate the load parameters. This algorithm can be implemented using logic circuits. Moreover, using autotuning, the proposed algorithm can be applied without load information. An operating principle for the power stage switching devices called single-side firing is also proposed. Single-side firing solves the dead-time problem, allowing the PWM frequency to be increased and the sampling rate to be raised. This paper explains the current control algorithm, single-side firing principle, and implementation of the proposed scheme in detail. Simulations and experimental results are given to show the validity of this scheme View full abstract»

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  • Design of integrated magnetic elements using thick-film technology

    Publication Year: 1999 , Page(s): 408 - 414
    Cited by:  Papers (12)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (244 KB)  

    One of the most important aims in the electronic industry is the integration of magnetic elements, since it allows the reduction of the size of power electronics equipment. This paper presents a method of designing integrated magnetic elements using thick-film technology. A DC-to-DC converter has been built and tested to validate this technology. Experimental results obtained and conclusions are also presented View full abstract»

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  • Design and implementation of an FPGA-based control IC for AC-voltage regulation

    Publication Year: 1999 , Page(s): 522 - 532
    Cited by:  Papers (37)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (260 KB)  

    This paper presents a field-programmable gate army (FPGA)-based control integrated circuit (IC) for controlling the pulsewidth modulation (PWM) inverters used in power conditioning systems for AC-voltage regulation. We also propose a multiple-loop control scheme for this PWM inverter control IC to achieve sinusoidal voltage regulation under large load variations. The control scheme is simple in architecture and thus facilitates realization of the proposed digital controller for the PWM inverter using the FPGA-based circuit design approach. Bit-length effect of the digital PWM inverter controller has also been examined in this paper. The designed PWM inverter control IC has been realized using a single FPGA XC4005 from Xilinx Inc., which can be used as a coprocessor with a general-purpose microprocessor in application of AC-voltage regulation. Owing to the high-speed nature of FPGA, the sampling frequency of the constructed IC can be raised up to the range that cannot be reached using a conventional digital controller based merely on microcontrollers or a digital signal processor (DSP). Experimental results show the designed PWM inverter control IC using the proposed control scheme can achieve good voltage regulation against large load variations View full abstract»

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  • An RC load model of parallel and series-parallel resonant DC-DC converters with capacitive output filter

    Publication Year: 1999 , Page(s): 515 - 521
    Cited by:  Papers (49)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (232 KB)  

    A novel analytical methodology is proposed and applied to investigate the steady-state processes in voltage-fed parallel and series-parallel resonant DC-DC power converters with a capacitive output filter. In this methodology, the rectifier, output capacitor and load are replaced by an equivalent circuit which includes a capacitor and resistor connected in parallel. Excellent agreement was obtained when comparing numerical values calculated by the proposed model to cycle-by-cycle SPICE simulation and to the numerical results of earlier studies View full abstract»

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  • Coreless printed circuit board (PCB) transformers for power MOSFET/IGBT gate drive circuits

    Publication Year: 1999 , Page(s): 422 - 430
    Cited by:  Papers (10)  |  Patents (13)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (248 KB)  

    Gate drive circuits for modern power electronic switches, such as MOSFET and insulated gate bipolar transistor (IGBT), often require electrical isolation. This paper describes the modeling and experimental results of some coreless printed circuit board (PCB)-based transformers that can be used for MOSFET and IGBT devices at high-frequency (500 kHz to 2 MHz) operation. PCB-based transformers do not require the manual winding procedure and thus simplify the manufacturing process of transformer-isolated gate drive circuits. With no core loss, coreless transformers are found to have favorable characteristics at high-frequency operations. This project demonstrates an important point that the size of the magnetic core can approach zero and become zero when the frequency is sufficiently high View full abstract»

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  • Efficient simulation of switched networks using reduced unification matrix

    Publication Year: 1999 , Page(s): 481 - 494
    Cited by:  Papers (12)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (248 KB)  

    A new and simple formulation method for switched networks in the numerical time domain is presented. Unification models of switching devices, companion models of energy-storage elements, and several straightforward circuit-manipulated operations are used in obtaining a reduced unification matrix (RUM). The feature of the constant formulated RUM is clarified, and the selection of the main parameters of unification models is illustrated. A condition of reducibility is proposed to determine how small the dimensions of a modified nodal matrix (MNM) can be reduced to. Simulation results using the RUM method demonstrate its superiority over the commonly used MMM method, not only for memory requirements, but also for computational speed. A large circuit example shows that the RUM method offers a 76.32% time savings in computation. Additionally, the RUM method possesses the merits of easy formulation, easy programming and more realistic switch modeling, as well as greater accuracy and higher time efficiency when compared with commonly used state-space approaches. These combined advantages should make the proposed RUM method very attractive in the time-domain simulation of switched networks. For large switched networks, the decided advantages are very great View full abstract»

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  • Coreless printed circuit board (PCB) transformers with multiple secondary windings for complementary gate drive circuits

    Publication Year: 1999 , Page(s): 431 - 437
    Cited by:  Papers (18)  |  Patents (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (188 KB)  

    This paper describes the modeling and implementation of a coreless printed circuit board (PCB)-based transformer with “multiple” secondary outputs. This new PCB transformer has been successfully applied in complementary gate drive circuits in a novel low-profile power converter with high-power density and a converter bridge. The PCB-based transformers do not require the manual winding procedure and thus simplify the manufacturing process of transformer-isolated gate drive circuits. The use of the multiple secondary outputs can in principle simplify the complementary gate drive circuits that are often required in many power electronics applications View full abstract»

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  • Charge pump power-factor-correction dimming electronic ballast

    Publication Year: 1999 , Page(s): 461 - 468
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (184 KB)  

    A voltage-source charge pump power-factor correction (CPPFC) continuous dimming electronic ballast is proposed in this paper. The basic charge pump PFC principle is presented, and its unity power factor condition is then reviewed. Constant lamp power control and crest factor correction technique in dimming mode operation are then discussed. A continuous dimming controller with average lamp current control and duty-cycle modulation is developed so that the lamp is able to operate in constant power and low crest factor from 20% to 100% dimming level. The developed dimming electronic ballast has features of higher than 0.99 power factor, low crest factor, and low-DC-bus voltage View full abstract»

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  • Improved large-signal performance of paralleled DC-DC converters current sharing

    Publication Year: 1999 , Page(s): 573 - 577
    Cited by:  Papers (19)  |  Patents (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (112 KB)  

    This paper introduces fuzzy logic control as a technique for significantly improving the large-signal performance of paralleled DC-DC power converters with master-slave current sharing control. The control design for such systems is challenged by its high modeling complexity, and present approaches which come only from a small-signal perspective unable to give a good response for wide load and line transients. The fuzzy logic approach, by dealing naturally with nonlinearities, offers a good and parameter-insensitive transient response for the current sharing loop. The design methodology of the fuzzy compensator, simulation results, and a comparison with existing classical designs are shown View full abstract»

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  • A buck quadratic PWM soft-switching converter using a single active switch

    Publication Year: 1999 , Page(s): 445 - 453
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (344 KB)  

    High-switching frequency associated with soft commutation techniques is a trend in switching converters. Following this trend, a buck pulsewidth modulation (PWM) converter is presented. The DC voltage conversion ratio of this converter has a quadratic dependence on duty cycle, providing a large stepdown. This new buck quadratic PWM soft-single-switched converter, having only a single active switch, provides a high efficient operating condition for a wide load range at high-switching frequency. In order to illustrate the operating principle of this new converter, a detailed study including theoretical analysis, relevant equations and simulation, and experimental results is carried out View full abstract»

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  • Monitoring of paralleled IGBT/diode modules

    Publication Year: 1999 , Page(s): 438 - 444
    Cited by:  Papers (23)  |  Patents (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (236 KB)  

    A method is presented to monitor the state of a converter with an unlimited number of paralleled insulated gate bipolar transistor (IGBT)/diode modules with individual gate drives. The monitoring functions can be implemented without extra signal processing or load-side components. The method is based on the active gate-controlled current balancing (CB) principle. This principle is reviewed in the first part of this paper, and the necessary supplements to implement the monitoring functions are shown. In the second part, experimental measurements are shown. This new control method allows monitoring the state of a converter and balancing the losses and current sharing between paralleled power devices, without the need to match the devices nor the gate drives. Thus, the overall reliability can be increased without increasing the costs. Since no matching of the devices is needed, the handling and logistic costs can be significantly reduced. IGBT/diode modules for standard paralleling are selected, and only modules of the same class can be paralleled without excessive derating. The presented method allows switching off one of the paralleled branches in the case of parameter degradation and to keep the converter operating at a lower power View full abstract»

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  • Optimal operation of coreless PCB transformer-isolated gate drive circuits with wide switching frequency range

    Publication Year: 1999 , Page(s): 506 - 514
    Cited by:  Papers (40)  |  Patents (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (248 KB)  

    Gate drive circuits for power MOSFETs and insulated gate bipolar transistors (IGBTs) often require electrical isolation. Coreless printed circuit board (PCB) transformers have been shown to have desirable characteristics from a few hundreds of hertz to a few megahertz and can be used for both power and signal transfer at low-power level. At low operating frequency, the magnetizing inductance has such low impedance that the driving power requirement could become excessive. This paper describes the use of a coreless PCB transformer for isolated gate drive circuits over a wide-frequency range. Based on a resonance concept, the optimal operating condition that minimizes the power consumption of the gate drive circuits is developed and verified with experiments. The coreless PCB transformer demonstrated here confirms a fundamental concept that the size and volume of a magnetic core could approach zero and become zero if the operating frequency is sufficiently high. Coreless PCB transformers do not require the manual winding procedure and thus simplify the manufacturing process of transformer-isolated gate drive circuits and low-power converters. Their sizes can be much smaller than those of typical core-based pulse transformers. The electrical isolation of a PCB is much higher than that of an optocoupler View full abstract»

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  • Steady-state analysis of the series resonant DC-DC converter in conjunction with loosely coupled transformer-above resonance operation

    Publication Year: 1999 , Page(s): 469 - 480
    Cited by:  Papers (10)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (300 KB)  

    This paper presents the steady-state analysis of the series resonant DC-DC power converter (SRC) in conjunction with loosely coupled transformer (LCT) operating above resonance (fs/fo>1). It is an extension of the conventional steady-state analysis of the SRC. Three operational modes other than the continuous current mode (CCM) have been identified, and the boundaries of all the operational modes are defined. Based on the well-defined operational plane, all the operational modes are analyzed. Results are given in normalized form and experimentally verified View full abstract»

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Aims & Scope

IEEE Transactions on Power Electronics covers fundamental technologies used in the control and conversion of electric power.

Full Aims & Scope