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Electric Power Applications, IEE Proceedings -

Issue 6 • Date Nov 1997

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Displaying Results 1 - 14 of 14
  • True average current predictive controller for four-wire PWM reversible rectifiers

    Publication Year: 1997 , Page(s): 397 - 400
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (372 KB)  

    A proposed predictive controller suitable for four-wire boost rectifiers is described. The predictive controller regulates the rectifier line currents and includes a method of providing true average current mode control. The performance of the rectifier is demonstrated using simulation results for an 80 kVA rated converter switching at 15 kHz. Practical requirements for the controller are discussed View full abstract»

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  • Analysis and design of a flyback zero-current switched quasiresonant AC/DC converter

    Publication Year: 1997 , Page(s): 401 - 408
    Cited by:  Papers (6)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (596 KB)  

    A flyback zero-current switched (ZCS) quasiresonant AC/DC converter, functioning as a power factor correction regulator, is presented and analysed in detail. Only one active switch with simple control logic is required to achieve both input current waveshaping and output voltage regulation. The investigation of voltage and current waveforms of the proposed converter is followed by simulation and leads to a design example to verify the theoretical results. An experimental unit of 120 W was built which confirmed the analysis and simulated results View full abstract»

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  • Synchronisation problem of high performance reluctance motors

    Publication Year: 1997 , Page(s): 456 - 460
    Cited by:  Papers (3)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (404 KB)  

    The paper reports an investigation of the synchronisation problem of three phase high performance reluctance motors. This problem stems from the fact that these motors can have extremely high reactance ratio and hence a significant pull-out torque. While this is a welcomed property from a steady state stability point of view, it can make the process of synchronisation a difficult task. To carry out this investigation a rigorous state space model in the original phase values reference frame was developed and simulated. The developed model takes into consideration the effect of torsional dynamics. This is augmented by a steady state analysis based on Park's two-axis reference frame View full abstract»

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  • Eddy current losses and hot-spot evaluation in cover plates of power transformers

    Publication Year: 1997 , Page(s): 435 - 440
    Cited by:  Papers (17)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (536 KB)  

    Heavy current bushings passing through steel cover plates and housing walls of power transformers, generators and other large power equipment are thermally hazardous elements of construction and a source of additional power losses. The safety and reliability of such expensive objects and the safety of power delivery often depend on the proper design of these elements. A computer analysis, based on Maxwell equations and analytical representation of electromagnetic field has been carried out. The nonlinear permeability of solid steel was considered using an analytical approximation. Eddy current losses have been calculated and compared using different experimental and calculation methods. Electromagnetic criteria were used to forecast possible excessive heating and hot spots. Various constructional means of loss and hot spot reduction were considered View full abstract»

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  • Sequence impedance and equivalent circuit of a converter system

    Publication Year: 1997 , Page(s): 409 - 414
    Cited by:  Papers (5)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (560 KB)  

    The author describes a means of deriving the sequence impedance and equivalent circuit of a power converter at fundamental frequency. The technique used is based on modulation theory, and the results can be used in the analysis of converter systems under unbalanced operation. The effect of commutation overlap is represented by a modified switching function so that an accurate calculation can be carried out. The method proposed provides a simple model for power converters which can be used in the steady-state analysis of unbalanced power systems containing several converters. Case studies using a simple converter system and a realistic power supply system have been carried out, and the results obtained confirm the validity of the method proposed View full abstract»

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  • Parallel connection of single-switch three-phase power-factor correction converters for interleaved switching

    Publication Year: 1997 , Page(s): 423 - 433
    Cited by:  Papers (8)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (948 KB)  

    A circuit for the parallel connection of multiple high-frequency three-phase power-factor-correction converters is proposed which enables their input and output current ripple to be interleaved. Such interleaved operation substantially improves the composite power factor, line-current ripple and output-voltage ripple. The improvement is investigated by developing solutions to circuit state equations which allow the high-frequency content of the line current, as well as the low-order line-frequency harmonics, to be computed. Conclusions drawn from the computed results are verified experimentally using a 1 kW, two-stage, interleaved converter View full abstract»

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  • Performance characteristics of dual-winding reluctance generators

    Publication Year: 1997 , Page(s): 461 - 468
    Cited by:  Papers (3)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (708 KB)  

    In this paper, a dual winding reluctance generator with mixed poles is analysed to determine its performance characteristics. The loads (impedance or rectifier) are connected to a set of 2-pole, 3-phase windings which are capacitively compensated, while more reactive power is provided to the load by another 6-pole, 3-phase control winding to which another 3-phase capacitor bank is connected. A q-d equivalent circuit model accounting for saturation of the magnetic paths and saturation-dependent core and harmonic loss resistances is given, which accurately predicts experimental results View full abstract»

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  • Modelling and design of a reversible three-phase switching mode rectifier

    Publication Year: 1997 , Page(s): 389 - 396
    Cited by:  Papers (9)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (604 KB)  

    A reversible three-phase switching mode rectifier consisting of a four-active-switch and without current sensor is proposed. To achieve controllable power factor, clean sinusoidal input current, adjustable DC output voltage, and bidirectional power flow capability, a closed-form pulse width modulation (PWM) duty cycle function is derived. The popularly used state space averaging technique is extended for modelling the reversible three-phase four-active-switch rectifier. The space vector representation technique is then used to simplify the modelling process without sacrificing accuracy and frequency range. Both steady-state and signal analyses are made. Results show that the proposed closed-form control law for the rectifier can indeed achieve the desired property. Moreover, the rectifier also possesses a bidirectional power flow capability, which is useful for many applications. Finally, a prototype hardware circuit was constructed and experimental results are presented for demonstration. Guidelines for determining the LC parameters and the PI controller gains are described briefly in the text View full abstract»

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  • Robust speed control of brushless DC motor using adaptive input-output linearisation technique

    Publication Year: 1997 , Page(s): 469 - 475
    Cited by:  Papers (9)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (580 KB)  

    A robust speed control scheme for a brushless DC (BLDC) motor using an adaptive input-output linearisation technique is presented. By using this technique, the nonlinear motor model can be linearised in Brunovski canonical form, and the desired speed dynamics can be obtained based on the linearised model. This control technique, however, gives an undesirable output performance under the mismatch of the system parameters and load conditions caused by the incomplete linearisation. For the robust output response, the disturbance torque and flux linkage will be estimated by a model reference adaptive technique. The adaptation laws are derived by the Popov's hyperstability theory and positivity concept, The proposed scheme is implemented on a BLDC motor using the software of DSP TMS320C30 and the effectiveness is verified through the comparative simulations and experiments View full abstract»

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  • High-frequency switching-mode power amplifier for shaker armature excitation

    Publication Year: 1997 , Page(s): 415 - 422
    Cited by:  Papers (7)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (636 KB)  

    The paper presents the design and implementation of a switching-mode power amplifier for shaker armature excitation. First, the dynamic model of a current-source-driven shaker system is derived. Then a novel current-controlled PWM scheme is proposed for performing the switching control of the inverter. To obtain good reference-current tracking-control characteristics over a wide frequency range, the feedback-current controller is augmented with a command-feedforward controller and a robust disturbance-feedforward controller. In the design of the disturbance-feedforward controller, the disturbance observer and robust-control technique are developed to make it practically feasible and have robust control performance. The design of the proposed controller is described in detail and practical limitations and the implementation of the current controller are discussed. Some measured results are provided to demonstrate the performance of the developed switching-mode power amplifier View full abstract»

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  • Modelling and simulation of the Torus generator

    Publication Year: 1997 , Page(s): 446 - 452
    Cited by:  Papers (3)  |  Patents (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (548 KB)  

    Multiphase Torus generators with rectified outputs are shown to exhibit mutual coupling effects which have a strong influence upon the waveshape of phase current. Formulae are derived for the calculation of inductances from machine dimensions and give good agreement with the measured parameters of an 11-phase machine. A PSpice simulation of the generator system is developed and is shown to yield accurate prediction of the generator performance, thus providing a design tool View full abstract»

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  • High power GTO thyristor chopper applications with passive snubber energy recovery

    Publication Year: 1997 , Page(s): 381 - 388
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (660 KB)  

    Single ended GTO thyristor chopper circuits find considerable use in high-power applications. The paper presents a single ended GTO chopper that achieves 100% recovery of all snubber energies. The limits of operation and minimum reset times are quantified and possible improvements to the basic circuit are presented. Circuit performance is supported by mathematical, time domain simulations and experimental results View full abstract»

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  • Phase co-ordinate approach to calculate earth-fault current and shock voltage

    Publication Year: 1997 , Page(s): 441 - 445
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (408 KB)  

    The paper summarises an alternative approach for the calculation of earth fault currents and shock voltages for low voltage systems up to 1000 V without using the conventional symmetrical components. As the shock voltage at each section of the installation has to be modelled during fault conditions, the system equations are formulated entirely in the phase co-ordinates including the representation of neutral and grounding conductors. Test results on two different earthing systems demonstrate the ability in modelling the untransposed cable parameters and the influence of the unbalanced load currents on the postfault voltages. More accurate results can thus be obtained as compared with other methods of calculation View full abstract»

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  • Regenerative- and plug-braking operations of inverter-fed asynchronous motors

    Publication Year: 1997 , Page(s): 453 - 455
    Cited by:  Papers (4)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (288 KB)  

    The paper analyses some suitable braking operations of asynchronous motors supplied by means of electronic power devices. Both regenerative- (or dissipative) and plug-braking operations are considered only in the steady-state. The most suitable speed ranges are investigated together with their intrinsic limitations, so that upper and lower boundary values are given. The practical flexibility of both braking operations is supported by an approximate investigation on the amounts of copper loss involved View full abstract»

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