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Electric Power Applications, IEE Proceedings B

Issue 3 • Date May 1989

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Displaying Results 1 - 6 of 6
  • Hysteresis current-forced three-phase voltage-sourced reversible rectifier

    Page(s): 113 - 120
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (760 KB)  

    A voltage-sourced reversible rectifier (VSRR) which achieves bidirectional power flow between a three-phase AC supply and a DC bus voltage is described. The device features a current-forced control strategy that has the advantages of simplicity and extremely fast response time, while operating with unity power factor and sinusoidal AC supply currents to produce a regulated DC bus voltage. Six power transistors provide the necessary control over the currents, and to prevent them from switching faster than their capability a hysteresis band is introduced into the control strategy. The paper investigates the effects of the hysteresis, inductance and transistor switching delays on switching rates, distortion and efficiency by using both simulated and experimentally obtained results.<> View full abstract»

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  • Improved PWM method of forced commutated cycloconvertors

    Page(s): 121 - 126
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (444 KB)  

    An unrestricted frequency changer (UFC), a well known forced commutated cycloconverter (FCC), is known to be suitable for variable speed AC drives, because it operates in all four quadrants and generates no subharmonic components. However, lower order undesired components in the output voltage and in the input current are still large and cause problems in practical applications. In the paper, an improved PWM method is proposed to reduce lower order harmonic components. The new method can completely eliminate two undesired harmonic components in the low output voltage ranges with a relatively low switching frequency. This harmonic elimination occurs both on the output voltage and on the input current simultaneously. The harmonic characteristics of the proposed FCC are shown by computer simulations and verified by experiments.<> View full abstract»

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  • Transient and steady-state performance of a squirrel-cage induction motor

    Page(s): 136 - 142
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (661 KB)  

    The paper gives a two-dimensional transient numerical analysis of a three-phase induction motor with a deep bar squirrel-case rotor under a voltage-forced operation. A combined explicit and implicit finite difference scheme is used to solve the problem. Regions of stator phase winding and rotor bar are solved by using a time-marching explicit scheme; the other regions of iron cores and air gap are solved together by the implicit scheme. The steady-state asymptotic solution of the electromagnetic field equation is calculated to simulate the motor operated at a constant rotor speed. The variations in torque, supplied current and rotor bar current, and their distributions with the rotor rotating speed, are obtained. Experimental work using a 1 h.p. squirrel-cage motor was carried out to verify the numerical results.<> View full abstract»

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  • Effects of constructional asymmetries on the characteristics of 2-phase permanent magnet synchronous motors

    Page(s): 143 - 150
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (604 KB)  

    The synchronous inductor motors studied in this paper have a construction identical to that of PM-type stepping motors, and they feature excellent start/stop characteristics and high torque with small input power. This type of synchronous motor is used mainly in recorders, printers, copying machines etc. to drive papers. Further, they are used in various controllers which need bidirectional rotation. The steady-state operating characteristics (alternating torque characteristics as well as starting characteristics), of asymmetrical synchronous inductor motors are studied mainly in comparison with symmetrical motors. Further, in consideration of the applications that need bidirectional rotation, the difference of characteristics in a different direction of rotation caused by mechanical asymmetry is also studied.<> View full abstract»

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  • Analysis of buck/boost zero-current-switching resonant DC/DC convertor

    Page(s): 127 - 135
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (628 KB)  

    A large signal steady-state analysis is presented for a buck/boost zero-current-switching resonant DC/DC power convertor. The basic equations governing convertor operation are derived. The following performance parameters are determined for lossless operation: current and voltage waveforms, peak currents and voltages of the switch and rectifier diode, ON switch duty cycles, maximum switching frequency, DC voltage transfer function, DC input resistance, power conversion capability, and circuit component values. These results lead to the design procedure. An example is given to illustrate the application of the developed theory View full abstract»

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  • Earth-leakage problems and solutions on the Tyne and Wear Metro

    Page(s): 152 - 160
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1268 KB)  

    The interference and corrosion effects of stray traction-return currents flowing through the earth have presented DC track-return railway operators and public utilities with problems for almost a century. The paper discusses the nature of these problems and the steps taken to include measures in the design and construction of the Tyne and Wear Metro to reduce them to acceptable levels. The formation and work of the Corrosion Working Party is explained, together with the problems encountered and solutions applied during the early years of the Metro operation. Conclusions are drawn and design guidelines set in the light of experience to date View full abstract»

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