IEE Proceedings - Electric Power Applications
Volume 146, Issue 3, May 1999
Volumes & issues:
Volume 146, Issue 3
May 1999
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- Author(s): H. Polinder and M.J. Hoeijmakers
- Source: IEE Proceedings - Electric Power Applications, Volume 146, Issue 3, p. 261 –266
- DOI: 10.1049/ip-epa:19990091
- Type: Article
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p.
261
–266
(6)
A gas-turbine driven, high-speed, high-efficiency generator system intended for use in series-hybrid vehicles is developed. It consists of a permanent-magnet generator with surface-mounted magnets and a six-pulse controlled rectifier. The stator currents of the rectifier-loaded generator contain time harmonics, which cause eddy-current losses in the magnets. These losses can be so high that they result in demagnetisation of the magnets. To reduce these losses, the magnets may be segmented. The aim of the paper is to model the eddy-current losses in such segmented magnets. This is done by incorporating magnet loss resistances in the equivalent circuits of the permanent-magnet machine. The model is verified by means of locked-rotor tests. To show the usefulness of the model, the losses in the magnets of a rectifier-loaded permanent-magnet machine are calculated. The eddy-current losses in the magnets can be decreased by increasing the number of magnet segments: these losses are proportional to the square of the magnet width. - Author(s): G. Narayanan and V.T. Ranganathan
- Source: IEE Proceedings - Electric Power Applications, Volume 146, Issue 3, p. 267 –275
- DOI: 10.1049/ip-epa:19990118
- Type: Article
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p.
267
–275
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The authors deal with space-vector-based generation of synchronised three-phase PWM waveforms with three-phase, half-wave and quarter-wave symmetries. The necessary and sufficient conditions for synchronisation and the waveform symmetries are brought out in terms of the inverter states. These conditions are applied to the conventional and modified forms of space vector modulation to generate synchronised PWM waveforms with all the symmetries. Further, the necessary conditions governing the numbers of switchings of the different phases in any given sector to maintain the symmetries are identified. These rules are used to develop two new clamping strategies, namely the asymmetric zero-changing strategy and the boundary sampling strategy, which exploit the flexible features of space vector methods like double-switching of a phase and clamping of two phases in a sampling period. Typical waveforms corresponding to the different strategies are presented along with their theoretical and experimental spectra. The performance assessment of these strategies and their application to drives are dealt with in Part 2. - Author(s): G. Narayanan and V.T. Ranganathan
- Source: IEE Proceedings - Electric Power Applications, Volume 146, Issue 3, p. 276 –281
- DOI: 10.1049/ip-epa:19990119
- Type: Article
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p.
276
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The harmonic distortion due to the four space-vector-based synchronised PWM strategies discussed in Part 1 is studied in the whole linear modulation range. Different strategies give the best performance for different ranges of fundamental voltage V1. A hybrid PWM using the different strategies at appropriate voltages is proposed. Theoretical and experimental results show that this hybrid PWM results in a significant reduction in harmonic currents in V/f drives with a base frequency of 50 Hz and different maximum switching frequencies fsw(max) of the inverter. Experimental results show that the current transients during change of pulse number are also reduced. Compared to the other real-time, open-loop, synchronised PWM techniques with a uniform sampling rate, the proposed hybrid PWM shows superior performance in the medium-voltage range. In the high-voltage range, its performance is inferior only to that of the more complicated high-voltage suboptimal (HVSO) strategy. With fsw(max) = 450 Hz, the harmonic distortion in the whole speed range of the drive is brought down to less than that of a six-step operation, which is regarded as an acceptable level for such low switching frequencies. This has not been possible with other comparable strategies. - Author(s): G. Garcia Soto ; E. Mendes ; A. Razek
- Source: IEE Proceedings - Electric Power Applications, Volume 146, Issue 3, p. 282 –288
- DOI: 10.1049/ip-epa:19990293
- Type: Article
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p.
282
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The paper deals with robust parameter estimation (rotor and stator resistances), shaft speed estimation, and flux observation of induction motors using the extended Kalman filter (EKF) technique. The novelty of the paper is that it develops the EKF in a frame rotating synchronously with the stator current vector with the use of a reduced dynamic motor model in order to economise the computational requirements of the EKF. Different problems have been studied. First, the EKF technique is applied to the estimation of the rotor and stator resistances. This is used for the indirect field-oriented control of the induction machine. Next, the EKF technique is applied to the estimation of the induction machine rotor fluxes and rotor resistance, and is used to perform the direct field oriented control of the induction machine. Finally, speed sensorless control is carried out. In this case, the rotor flux and the motor shaft speed are estimated. Computer simulations and experimental tests have been carried out to show the effectiveness of the proposed methods. - Author(s): Y.S. Lai
- Source: IEE Proceedings - Electric Power Applications, Volume 146, Issue 3, p. 289 –296
- DOI: 10.1049/ip-epa:19990108
- Type: Article
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p.
289
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The purpose of the paper is to present a new inverter control technique which not only mitigates the common mode voltage for motor drives but also significantly reduces the calculations required for high switching frequency control, in comparison with the conventional space vector modulation technique. Moreover, it is demonstrated that the presented technique improves the quality of inverter control by randomising the inverter switching frequency, thereby spreading the first dominant harmonic cluster which contributes to the noise. Experimental results derived from a microprocessor-based experimental drive system are presented to confirm the theoretical analysis. - Author(s): R.-J. Wai and F.-J. Lin
- Source: IEE Proceedings - Electric Power Applications, Volume 146, Issue 3, p. 297 –308
- DOI: 10.1049/ip-epa:19990290
- Type: Article
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p.
297
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A sliding-mode controller with an integral-operation switching surface is adopted to control the position of an induction servo motor drive. Moreover, to relax the requirement for the bound of uncertainties, a fuzzy neural network (FNN) sliding-mode controller is investigated, in winch the FNN is utilised to estimate the bound of uncertainties real-time. The theoretical analyses for the proposed FNN sliding-mode controller are described in detail. In addition, to guarantee the convergence of tracking error, analytical methods based on a discrete-type Lyapunov function are proposed to determine the varied learning rates of the FNN. Simulation and experimental results show that the proposed FNN sliding-mode controller provides high-performance dynamic characteristics and is robust with regard to plant parameter variations and external load disturbance. Furthermore, comparing with the sliding-mode controller, smaller control effort results, and the chattering phenomenon is much reduced by the proposed FNN sliding-mode controller. - Author(s): F.P. Dawson ; F.P. Mukhopadhyay ; M. Iwahara ; S. Yamada
- Source: IEE Proceedings - Electric Power Applications, Volume 146, Issue 3, p. 309 –316
- DOI: 10.1049/ip-epa:19990292
- Type: Article
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p.
309
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The authors report on the development of a passive magnetic fault current limiter (FCL) with the following attributes: compactness, small size, reliable and fail-safe operation, and zero reset time. The limiter consists of two magnetic devices connected in series and in magnetic counter opposition to each other. Two designs are considered. In one design, Nd–Fe–B permanent magnets are sandwiched between the pole faces of two saturable ferrite E-cores. In the other design, Nd–Fe–B permanent magnets are sandwiched between the pole faces of two steel E-cores with built in zones of constriction. A design procedure is developed and a design example for the ferrite and steel based core is illustrated. The transient performance of both FCL designs is simulated by means of the tableau approach. Experimental results for both designs are presented to verify the validity of the proposed tableau approach, the design procedure and the functional operation. - Author(s): C.M. Liaw ; T.H. Chen ; W.L. Lin
- Source: IEE Proceedings - Electric Power Applications, Volume 146, Issue 3, p. 317 –324
- DOI: 10.1049/ip-epa:19990104
- Type: Article
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p.
317
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The authors present the dynamic modelling and control of a switching-mode rectifier (SMR) with step up/down voltage and power factor correction control. Depending on the output voltage level, this rectifier can be operated in buck or boost mode during each AC half cycle. It follows that this SMR possesses wide DC output voltage range, and it can be used as a battery charger with large charging flexibility for a serially connected battery bank. The power circuit of the proposed rectifier is first analysed and designed. Then its dynamic model is derived. Based on this, a current waveform controller is designed, such that sinusoidal line current with low harmonics and near unity power factor is obtained. In addition, a charging controller is also designed for yielding good dynamic charging characteristics. After confirming the validity of the designed rectifier by simulations, the circuit implementation is performed and some measured results are provided for further demonstrating its performance. - Author(s): K. Chatterjee ; B.G. Fernandes ; G.K. Dubey
- Source: IEE Proceedings - Electric Power Applications, Volume 146, Issue 3, p. 325 –334
- DOI: 10.1049/ip-epa:19990298
- Type: Article
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p.
325
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A novel high-power low-distortion static VAr compensator is proposed. The harmonics are eliminated by combining low-frequency high-power devices and high-frequency low-power devices. The effectiveness of the proposed scheme is investigated for a case where it is specifically used for load compensation and also for the case where it is used as a general-purpose VAr generator. A mathematical model of the VAr compensator is presented. Detailed simulation studies of the scheme are provided. Steady-state experimental results obtained from a scaled-down laboratory prototype are provided to demonstrate the viability of the proposed method. - Author(s): G.N. Bathurst ; B.C. Smith ; N.R. Watson ; J. Arrillaga
- Source: IEE Proceedings - Electric Power Applications, Volume 146, Issue 3, p. 335 –340
- DOI: 10.1049/ip-epa:19990294
- Type: Article
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p.
335
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A technique is described to model phase-shifting converter transformers in the harmonic domain. The model has been incorporated into a unified Newton solution technique which permits solution of high-pulse installations with parallel DC connections. A variety of test cases are included to illustrate the characteristics of a 24-pulse installation under both ideal and non-ideal conditions. The results show that the characteristic DC harmonics for an individual converter in a multi-pulse parallel connection installation increase with pulse number rather than decrease as with a series connection. - Author(s): C. Newton and M. Sumner
- Source: IEE Proceedings - Electric Power Applications, Volume 146, Issue 3, p. 341 –349
- DOI: 10.1049/ip-epa:19990103
- Type: Article
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p.
341
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The paper considers the problem of providing four regulated DC sources for use in a diode clamped five-level inverter. The preferred approach is to provide a single DC link supply and subdivide this into five levels using four series connected capacitor banks which have equally balanced voltages. The paper first considers the use of modified output switching strategies to redistribute energy through the DC link capacitors and maintain correct voltage balance, but concludes that this technique is restricted to outputs with a low modulation. The paper then presents a new technique whereby the voltage across each of these capacitors is maintained constant using a switching circuit: the balancer circuit. The design and control of the balancer circuit is described and its operation is validated on an 11 kW prototype vector controlled induction motor drive. Full four-quadrant operation is demonstrated. This arrangement eliminates the need for complex isolated supply arrangements typically found in multilevel drives. The balancer circuit takes the form of a fourth output leg with the addition of two inductors. This circuit is certainly viable for medium voltage drive applications. - Author(s): R.J. Hill and J. Bouillevaux
- Source: IEE Proceedings - Electric Power Applications, Volume 146, Issue 3, p. 350 –360
- DOI: 10.1049/ip-epa:19990115
- Type: Article
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p.
350
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A methodology for quantifying the safety and reliability performance of comma-free codes for railway track circuit data transmission under high levels of Gaussian noise is presented. Two decoding algorithms are described, based on the correct reception of one and two consecutive codewords, respectively. It is shown that use of the second algorithm in conjunction with a sub-dictionary with a minimum word distance constraint gives comparable safety and reliability performances to those obtained using longer-length synchronisable error-detecting codes. The paper also contains an outline of the properties of traction noise, knowledge of which is necessary for the design of digital railway data transmission systems.
Eddy-current losses in the segmented surface-mounted magnets of a PM machine
Synchronised PWM strategies based on space vector approach. Part 1: Principles of waveform generation
Synchronised PWM strategies based on space vector approach. Part 2: Performance assessment and application to V/f drives
Reduced-order observers for rotor flux, rotor resistance and speed estimation for vector controlled induction motor drives using the extended Kalman filter technique
New random inverter control technique for common mode voltage mitigation of motor drives
Fuzzy neural network sliding-mode position controller for induction servo motor drive
Analysis, design and experimental results for a passive current limiting device
Dynamic modelling and control of a step up/down switching-mode rectifier
New high-power low-distortion synchronous-link-converter VAr compensator
Harmonic domain modelling of high-pulse converters
Novel technique for maintaining balanced internal DC link voltages in diode clamped five-level inverters
Safety and reliability of comma-free digital coding for railway track circuits
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