By Topic

Electric Power Applications, IEE Proceedings -

Issue 2 • Date Mar 1999

Filter Results

Displaying Results 1 - 15 of 15
  • Power factor improvement using DCM Cuk converter with coupled inductor

    Page(s): 231 - 236
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (432 KB)  

    Most of the power factor regulator topologies in continuous conduction mode result in bulky magnetics, and in discontinuous conduction mode result in high harmonic content. To solve these problems a Cuk topology is presented in discontinuous conduction mode (DCM) with coupled inductors for power factor regulation, the unique feature exhibited by the converter that makes the converter better than the other converter in DCM operation for power factor regulation. Inductive coupling is used to transfer the ripple from the input to the output side thereby reducing the switching harmonics in the line current. Experimental results obtained on a 500 W prototype are also presented View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Novel PFC converter suitable for engine-driven generator-interactive three-phase power systems

    Page(s): 253 - 260
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (572 KB)  

    Discontinuous current mode control implementation for three-phase AC-DC converters with active power filtering and power factor correction schemes has attracted special interest in industrial and telecommunication energy systems. This control strategy has practical advantages since it has a simple and cost-effective configuration. However, for emergency engine-driven generators, most three-phase PFC converters with discontinuous current mode control have not been effectively adopted in practice because the conventional PFC circuit configuration has some disadvantages for engine-driven generators connected to three-phase AC mains. A new conceptual PFC converter circuit and system configuration operating with discontinuous current mode control and suitable for engine-driven generators connected to three-phase AC mains is proposed. The operating principle and unique features of the proposed PFC converter is discussed in terms of harmonic currents and PFC converter performance evaluations on the basis of simulation results from two types of conventional three-phase PFC converters View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Three-phase flux reversal machine (FRM)

    Page(s): 139 - 146
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (520 KB)  

    A flux reversal machine (FRM) is a doubly-salient stator-permanent magnet (PM) machine with a windingless rotor, where the flux reverses polarities in the stator concentrated coils. The FRM may be built in single- or multiple-phase configurations. The three-phase FRM is studied in terms of magnetic field distribution, cogging and interaction torque and self and mutual inductances through finite element analysis (2-D FEA). Rotor/stator geometrical variables that influence the cogging and interaction torques are identified. Rotor skewing to reduce the cogging torque is successfully demonstrated. A suboptimised configuration based on an initial-geometry prototype is documented. Other potential two-, three- and five-phase pole combinations with adequate rotor skewing angle are also given. Low electrical time constant. Low torque ripple and good torque density in a rugged, easily manufactured, novel machine (the 3 phase machine) are proved through FEA. The encouraging results obtained through FEA constitute a strong foundation for the optimal design, and for the analysis of FRM transients and control View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • SVM-based hysteresis current controller for three-phase PWM rectifier

    Page(s): 225 - 230
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (408 KB)  

    A space vector modulation (SVM) based hysteresis current controller (HCC) for the pulse width modulated rectifier is proposed. The proposed technique utilises all the advantages of the HCC and SVM techniques. The controller determines a set of space vectors from a region detector and applies a space vector, selected according to the HCC. A set of space vectors, including the zero vector to reduce the number of switchings, is determined from the output signals of three comparators. A simple hardware implementation is proposed, and experimental results of the SVM-based HCC are shown View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Three-phase soft-switching voltage source converters for motor drives. I. Overview and analysis

    Page(s): 147 - 154
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (732 KB)  

    In the last twenty years, industrial and academic research has produced over one hundred new resonant and soft switching voltage source converter topologies. Regrettably, most of the published work has been directed toward a single topology, giving an overall impression of a large number of unconnected, competing techniques. To provide insight into this wide-ranging subject area, an overview of converter topologies is presented. Each topology is classified according to its mode of operation, and a family tree is derived, encompassing all converter types. Selected converters in each class are analysed, normalised performance figures are determined and key operational characteristics identified. Issues associated with the practical implementation of the analysed topologies are discussed in detail. The following topologies are analysed: soft switching DC-link converters, basic resonant DC-link inverter (BRDCL), clamped BRDCL, clamped quasi-resonant DC-link, parallel resonant DC-link inverter, and pole-commutated inverters View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Three-phase soft-switching voltage source converters for motor drives. II. Fundamental limitations and critical assessment

    Page(s): 155 - 162
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (700 KB)  

    Fundamental limits to soft-switching power converter performance are established by examining the detailed physical behaviour of bipolar power semiconductors. It is found that the soft-switched resonant transition time must be much longer than the semiconductor high-level carrier lifetime for effective reduction of switching losses. Constraints on PWM range and PWM resolution as a function of switching frequency are established for a range of soft-switching power converter topologies and the standard hard-switched inverter. For quasi-resonant DC-link topologies, the degradation in PWM resolution causes low-frequency harmonics to be introduced into the output spectrum. Topology-specific features are used to form a comparative assessment of the principal classes of soft-switched power converters. Resonant DC-link topologies are shown to produce the poorest output performance, although they offer the cheapest solution. Auxiliary resonant pole inverters can achieve levels of performance approaching those of the hard-switched topology, while retaining the benefits of soft-switching. It is concluded that the auxiliary commutated pole inverter offers the greatest potential for exploitation despite its relatively high capital cost. Modularisation of the active devices and optimisation of semiconductor design are identified as key objectives in the realisation of an economically viable system View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Automatic voltage regulator with fast dynamic speed

    Page(s): 201 - 207
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (548 KB)  

    A novel automatic voltage regulator is proposed and analysed. The power circuit is made up of a pulse-width modulated (PWM) buck-boost AC chopper which uses only two standard switch modules. In the AC chopper, the commutation scheme allows dead-time to avoid current spikes from switching and at the same time establishes a current path in the inductor to avoid voltage spikes. The AC chopper uses regenerative DC snubbers attached directly to power semiconductor modules to absorb energy stored in stray line inductances. These DC snubbers enhance the conversion efficiency and feature a very simple structure consisting only of a capacitor. A fast peak voltage detector for fast output voltage control is also proposed. It is shown, via experimental results, that the proposed scheme gives good dynamic and steady-state performances for a high-quality output voltage View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • DSP-based implementation of new random switching technique of inverter control for sensorless vector-controlled induction motor drives

    Page(s): 163 - 172
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (684 KB)  

    The DSP-based implementation of a new random switching technique of inverter control for sensorless vector-controlled induction motor drives is presented. All the necessary software schemes required for the implementation of the new random switching technique of inverter control for vector-controlled induction motor drives are developed in detail. The advantages and special features of the new random switching technique are highlighted and demonstrated. It is shown how simply the control system, including the inverter controller based upon the new random switching technique, and the sensorless vector controller, can be implemented by an off-the-shelf digital signal processor (DSP) starter kit using software, without resorting to additional analogue circuits or a dedicated inverter control chip. It is thereby demonstrated that the new random switching technique of inverter control can be easily incorporated into existing vector-controlled motor drive systems. Experimental results from a DSP-based sensorless vector-controlled drive system are presented to confirm the theoretical analysis, software and hardware design View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Variable structure adaptive control for PM synchronous servo motor drive

    Page(s): 173 - 185
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (808 KB)  

    A newly designed variable-structure controller for a permanent magnet (PM) synchronous servo motor drive, which is insensitive to uncertainties including parameter variations and external load disturbance, is introduced. To overcome the two main problems with variable-structure control, i.e. the assumption of known uncertainty bounds and chattering phenomena in the control effort, a variable-structure adaptive (VSA) controller is investigated. In the VSA controller a simple adaptive algorithm is utilised to estimate the uncertainty bounds; moreover, the chattering phenomenon is reduced. A variable-structure direct adaptive (VSDA) controller comprising the VSA control algorithm and a direct adaptation law is proposed to further improve the control performance of the variable-structure controller. The position control of a PM synchronous servomotor drive with the variable-structure control strategies is illustrated. Simulated and experimental results show that the developed controllers provide high-performance dynamic characteristics and are robust with regard to plant parameter variations and external load disturbance View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Development of a photovoltaic array model for use in power-electronics simulation studies

    Page(s): 193 - 200
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (628 KB)  

    To be able to develop a complete solar photovoltaic power electronic conversion system in simulation, it is necessary to define a circuit-based simulation model for a PV cell in order to allow the interaction between a proposed power converter (with its associated control arrangement) and the PV array to be studied. To do this, it is necessary to approach the modelling process from the perspective of power electronics; that is to define the desired overall model in terms of the manner in which the electrical behaviour of the cell changes with respect to the environmental parameters of temperature and irradiance. The authors cover the development of a general model which can be implemented on simulation platforms such as PSPICE or SABER and is designed to be of use to power electronics specialists. The model accepts irradiance and temperature as variable parameters and outputs the I/V characteristic for that particular cell for the above conditions View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Calculation of inductance in permanent-magnet DC motors

    Page(s): 129 - 137
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (736 KB)  

    The classical literature on DC motor design tends to focus on commutating inductance rather than total armature inductance, and does not provide a complete procedure for all the inductance calculations that are needed in permanent-magnet motors. The armature inductance is important, partly because of its effect on the electrical time constant, and partly because of its effect on the current waveform and torque when the motor is supplied from a phase-controlled converter or chopper. The inductance formulas needed in PM motors differ appreciably from those used with wound-field machines. The paper presents a comprehensive but concise account of the theory and computation of both the armature inductance and the commutating inductance in a form suitable for rapid computer calculation. In the armature inductance, new formulas for the airgap component are introduced and its importance is underlined by the fact that it accounts for about half the total inductance in several of the motors tested. This is an unexpected result, since the airgap component appears to have been overlooked in previous literature. Results are verified by experiment and finite-element analysis, and the paper describes the theoretical basis for the necessary connections to achieve the correct inductance by measurement View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • H loop-shaping control schemes for the buck converter and their evaluation using μ-analysis

    Page(s): 237 - 246
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (772 KB)  

    Two H loop-shaping control schemes for the buck converter are presented and compared to the existing linear quadratic scheme. The first control scheme is the H loop-shaping controller, and the second scheme is the current-assisted H loop-shaping. The evaluation of the proposed controllers is performed in terms of robust stability, control circuit complexity and robust performance of the converter. The powerful tool of μ-analysis is applied to examine the robust features of the buck converter, which employs any of the control schemes. It is shown that the current-assisted H loop-shaping control scheme exhibits better performance than the other two control schemes. This conclusion is verified by simulated and experimental results View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Negative output Luo converters: voltage lift technique

    Page(s): 208 - 224
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1004 KB)  

    The voltage lift technique is a popular method widely applied in electronic circuit design. Since the effect of parasitic elements limits the output voltage and power transfer efficiency of DC-DC converters, the voltage lift technique can lead to improvement of circuit characteristics. After long term research, this technique has been successfully applied for DC-DC converters. As with positive output Luo converters, negative output Luo converters are another series of new DC-DC step-up (boost) converters, which were developed from prototypes using the voltage lift technique. These converters perform positive to negative DC-DC voltage-increasing conversion with high power density, high efficiency and cheap topology in simple structure. They are different from other existing DC-DC step-up converters and possess many advantages, including a high output voltage with small ripples. Therefore, these converters will be widely used in computer peripheral equipment and industrial applications, especially for high output voltage projects View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Constant frequency, constant current load-resonant capacitor charging power supply

    Page(s): 187 - 192
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (480 KB)  

    A capacitor charging power supply incorporating a series-parallel load-resonant power converter, operating at resonance at a fixed frequency and providing a constant load current, is presented. A series-parallel load-resonant power converter containing three resonant components is shown to have three resonant frequencies. It is shown that one of the resonant frequencies can be independent of the load value. Furthermore such a power converter can be designed to supply constant current to a load. The circuit characteristics enable the power converter to efficiently charge a capacitor bank with minimum control circuitry. The resonant converter can be operated at a single frequency throughout the whole capacitor charging cycle from 0 V to 640 V. A power supply is constructed which delivers up to 2.6 kW to a large capacitor bank, charging the bank from 0 to 640 V at a constant switching frequency of 83 kHz. The power supply draws 0.9 power factor with no power factor correction circuitry View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Paralleling power converters for AC-DC step-down power conversion with inherent power factor correction

    Page(s): 247 - 252
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (452 KB)  

    The authors describe the modular development of a single-stage AC-DC step-down power converter. The converter offers advantages such as simple DC-DC type switching control, electrically isolated output and inherent power factor correction. It also provides single-stage power conversion without using power devices with excessively high voltage and current rating, the flexibility for expansion of power capability, and a simplification of design and production procedure for the manufacturing of power converter products. The operating modes of the converter are described and analysed. Experiments have confirmed the validity of the modular converter operation View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.