IEE Proceedings - Electric Power Applications
Volume 149, Issue 4, July 2002
Volumes & issues:
Volume 149, Issue 4
July 2002
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- Author(s): B.C. Mecrow ; J.W. Finch ; E.A. El-Kharashi ; A.G. Jack
- Source: IEE Proceedings - Electric Power Applications, Volume 149, Issue 4, p. 245 –254
- DOI: 10.1049/ip-epa:20020345
- Type: Article
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245
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The magnetic design of switched reluctance motors is examined and an alternative design presented in which the rotor is made from a series of discrete segments. Single-phase machines are initially examined and design rules established. Predictions of airgap force density are presented as a function of electric loading and compared with toothed rotor equivalents. It is shown that much greater force densities are theoretically possible with the segmental design. The authors then proceed to apply the concepts developed to a three-phase configuration, which shows particular advantages. Measured test results from a three-phase machine are presented and compared with a conventional switched reluctance motor of the same dimensions, revealing both the advantages and disadvantages of the segmental rotor configuration. - Author(s): J. Campbell and M. Sumner
- Source: IEE Proceedings - Electric Power Applications, Volume 149, Issue 4, p. 255 –260
- DOI: 10.1049/ip-epa:20020289
- Type: Article
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p.
255
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This paper describes the design and operation of a high performance sensorless induction motor drive. The drive derives its speed measurement from a model reference adaptive system, and hence high dynamic speed and torque response is obtained. The performance of the drive deteriorates as the motor heats up and motor parameters change. A specially trained artificial neural network is used to monitor these changes online. The advantage of this control system is that commissioning of the drive can be fully automated — nonlinear relationships are automatically characterized. - Author(s): J.M. Stephenson ; A. Hughes ; R. Mann
- Source: IEE Proceedings - Electric Power Applications, Volume 149, Issue 4, p. 261 –267
- DOI: 10.1049/ip-epa:20020373
- Type: Article
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p.
261
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The method for torque-ripple reduction in switched reluctance motors set out in a previous paper is developed. The online simplex optimisation, used to set the injected current harmonics for minimum torque ripple at low speed is explained and extended to higher speeds, at which control of the switching angles is exploited. Experimental results are included and the implications for motor and device ratings are addressed. - Author(s): D. Shen and P.W. Lehn
- Source: IEE Proceedings - Electric Power Applications, Volume 149, Issue 4, p. 268 –274
- DOI: 10.1049/ip-epa:20020377
- Type: Article
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268
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The paper presents a three-dimensional space-vector-modulation scheme for three-phase four-wire active power filters. The focus is on the implementation of a fixed frequency pulse width modulation (PWM) scheme with a minimum number of switch commutations per period and maximum DC bus voltage utilisation. For three-wire applications, space vector modulation is known to provide better utilisation of the DC voltage compared to a sinusoidal PWM approach. This concept is extended to four-wire applications by employing a four-leg active power filter. The largest symmetrical region in which the active filter's voltage space vector may reside is identified. Restricting the voltage space vector to this region avoids over-modulation and thereby prevents the production of low order harmonics. A digital controller is employed to provide deadbeat current control. The combination of the digital controller and the modulation scheme gives the four-leg active power filter the capability to independently track reference current waveforms in the three phases within one switching period. The four-leg active power filter may be used for harmonic compensation, reactive power compensation, load balancing, and neutral current compensation. Experimental results obtained from a 5 kVA laboratory active power filter validate the proposed modulation scheme as well as the control design. - Author(s): K. Nishida ; Y. Konishi ; M. Nakaoka
- Source: IEE Proceedings - Electric Power Applications, Volume 149, Issue 4, p. 275 –282
- DOI: 10.1049/ip-epa:20020257
- Type: Article
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An effective system control method is presented for applying a three-phase current-source PWM convertor with a deadbeat controller to active power filters (APFs). In the shunt-type configuration, the APF is controlled such that the current drown by the APF from the utility is equal to the current harmonics and reactive current required for the load. To attain the time-optimal response of the APF supply current, a two-dimensional deadbeat control scheme is applied to APF current control. To cancel both the delay in the two-dimensional deadbeat control scheme and the delay in DSP control strategy, an adaptive line enhancer (ALE) is introduced in order to predict the desired value of three sampling periods ahead. The ALE also brings robustness to the deadbeat control system. Owing to the ALE being in a transient state, the settling time is short. By comparison in a steady state, the total harmonic distortion ratio of source currents can be reduced as much as compared to the case that ideal identification of controlled system could be made. The experimental results obtained from a DSP-based APF are also reported. The compensating ability of this APF is very high in accuracy and responsiveness, although the modulation frequency is rather low. - Author(s): N.P. Papanikolaou and E.C. Tatakis
- Source: IEE Proceedings - Electric Power Applications, Volume 149, Issue 4, p. 283 –291
- DOI: 10.1049/ip-epa:20020370
- Type: Article
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The wide use of PFC converters as DC supplies for electrical and electronic applications over the last few years, in order to comply with EMC directives, has highlighted the issue of efficiency improvement in these converters. This paper presents a detailed study of the switching and power loss behaviour under any line and load conditions, for the case of PFC flyback converters operating in the continuous conduction mode (CCM). The whole analysis is based on the analytical calculation of the power factor (which drastically affects the conduction losses) and its variation in relation to the nop-solution that minimises the switching losses. As it will be proved theoretically, as well as by the use of simulation and experimental results, the operation of PFC flyback converters in the nop-area not only minimises the switching losses and limits the voltage stresses on the semiconductive elements, but also produces a high power-factor regulation. These facts, along with the simplicity of the flyback topology, establish the nop-solution for PFC flyback converters operating in the CCM as an optimal way to achieve high power-factor regulation, high efficiency and high power density. - Author(s): P. Syam ; P.K. Nandi ; A.K. Chattopadhyay
- Source: IEE Proceedings - Electric Power Applications, Volume 149, Issue 4, p. 292 –303
- DOI: 10.1049/ip-epa:20020298
- Type: Article
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Degradation of power quality in a cycloconverter-fed system due to subharmonics/interharmonics in the output is assessed by suitably defined input/output power quality indices. A simple yet effective method of reduction of subharmonics/low frequency interharmonics in the output of a cycloconverter is described, and the improvement in the power quality is demonstrated through simulation. The hardware implementation of the method is also presented with experimental results on a laboratory prototype of a cycloconverter-fed synchronous motor drive to show the effectiveness of this method. - Author(s): L. Xu and V.G. Agelidis
- Source: IEE Proceedings - Electric Power Applications, Volume 149, Issue 4, p. 304 –310
- DOI: 10.1049/ip-epa:20020374
- Type: Article
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p.
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A unified power flow controller (UPFC) based on the flying capacitor (FC) multilevel voltage-source converter (VSC) topology with phase-shifted sinusoidal pulse-width modulation (PWM) control is presented. This converter allows higher power handling, potentially lower power loss, lower harmonic distortion and hence less filtering requirements when compared with the typical two-level counterpart. The series converter injects a voltage with controlled magnitude and phase, to control the active/reactive power flow in a transmission line. The shunt converter absorbs/supplies active power demanded by the series converter to maintain a constant DC link voltage, also providing independent reactive support to the network. A complete model of the proposed UPFC system is shown and control circuits are described in the synchronous d-q frame. Finally, simulation results are provided to confirm the robustness of the proposed system. - Author(s): Y.-S. Jung and M.-J. Youn
- Source: IEE Proceedings - Electric Power Applications, Volume 149, Issue 4, p. 311 –316
- DOI: 10.1049/ip-epa:20020362
- Type: Article
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p.
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Small-signal modelling of an average-current mode control is proposed. To analyse the characteristics of the control scheme, a continuous-time small-signal model is derived. The derivation comes mainly from the analysis of the sampling effect present in the current control loop. By using the mathematical interpretation of a practical sampler representing the sampling effect of a current control loop, the small-signal model of an average-current mode control can be derived. To show the usefulness of the proposed model both simulation and experiment are carried out. The results show that the predicted results by the proposed model are in much better agreement with the measured ones than those of the conventional model, even though a high gain of the compensation network of the current control loop is employed.
Switched reluctance motors with segmental rotors
Practical sensorless induction motor drive employing an artificial neural network for online parameter adaptation
Online torque-ripple minimisation in a switched reluctance motor over a wide speed range
Fixed-frequency space-vector-modulation control for three-phase four-leg active power filters
Current control implementation with deadbeat algorithm for three-phase current-source active power filter
Minimisation of power losses in PFC flyback converters operating in the continuous conduction mode
Improvement in power quality and a simple method of subharmonic suppression for a cycloconverter-fed synchronous motor drive
Flying capacitor multilevel PWM converter based UPFC
Sampling effect in continuous-time small-signal modelling of average-current mode control
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