By Topic

Electric Power Applications, IEE Proceedings B

Issue 3 • Date May 1991

Filter Results

Displaying Results 1 - 6 of 6
  • Three-phase flyback AC-DC convertor with sinusoidal supply currents

    Page(s): 143 - 151
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (568 KB)  

    A three-phase flyback AC-DC convertor which has the step-up and step-down characteristics of output voltage, is described. The introduction of pulsewidth modulation makes it possible to obtain the sinusoidal supply currents with a near unity power factor. Three gate-turn-off thyristors provide the necessary control over the currents for unidirectional power flow. To improve upon the oscillatory transient operations, the tested system includes the digital PID controller using a microcomputer for output voltage regulations. The experimental results and state-space simulations confirm the usefulness of the presented convertor View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Decomposition of Czarnecki's reactive current and reactive power

    Page(s): 125 - 128
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (224 KB)  

    From the viewpoint of reactive power compensation, the decomposition of Czarnecki's reactive current component is discussed. When the number of harmonics present in the source voltage/current is higher than the number of reactive elements of the compensator, the reactive power can only be partially compensated. Thus the reactive current can be visualised as the sum of two components: the compensated reactive current and the residual reactive current. These two components are orthogonal, which can be used to estimate compensation effects View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Characteristics of a squirrel cage induction motor

    Page(s): 115 - 124
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (728 KB)  

    The authors investigate the magnetic field distribution in a 1 hp three-phase induction motor. Utilising a triangular finite-element method, the magnetic field in the motor is analysed at various balanced magnetomotive forces, and four different rotor positions. From the field solutions, the flux linkages and the slot leakages are found for a range of magnetising currents. An experiment using a straight laminated rotor core without aluminium bars is tested at the four locked positions by using a 20 kVA balanced three-phase transformer with a frequency of 60 Hz. The stator currents, line-to-line voltages and power factors are measured. The experimental data are compared with the calculated results and a reasonable agreement is found View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Design and implementation of a single phase current-forced switching mode bilateral convertor

    Page(s): 129 - 136
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (528 KB)  

    A single-phase switching mode bilateral convertor using current-forced hysteresis switching control is designed and successfully implemented. Based on the proposed current-forced switching scheme, the bidirectional power flow is very easy to control and the switching voltage jumps and losses can be reduced. Moreover, the line current can be sinusoidally regulated with unity power factor in the rectifier mode, and the voltage waveform distortion can be kept small in the inverter mode by instantaneous voltage control. To perform the control system design, the transfer function models of the proposed convertor system in two operation modes are built up, and then a generalised systematic design method is proposed to find the parameters of the controllers according to the prescribed specifications View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Computer simulation of three-phase prestriking transients in cable-connected motor systems

    Page(s): 105 - 114
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (864 KB)  

    Steep-fronted voltage transients, generated by prestriking conditions in circuit breakers and contactors when closing, produce severe interturn insulation stresses in machine windings. A computer program simulating the production of prestriking transients is described. The simulation is based on a full three-phase system representation, including busbars, switching device, cable and motor winding. The complex interaction between the system and the switching device, and also the interaction between the three poles of the switching device, are fully taken into account. A solution method based on the Fourier transform and using a combination of voltage and current generators to simulate switching actions is used in the calculations. Validation of the accuracy of the simulation is made by a comparison of on-site test results with the computer simulation View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • V curve of hysteresis motor

    Page(s): 137 - 141
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (324 KB)  

    The relation between the stator current and the field current of a synchronous motor at a constant terminal voltage and with a constant shaft load is known to be a V curve. It is shown, by both experiment and calculations, that the stator current of a hysteresis motor also shows a V curve. The mechanism of the V curve of the hysteresis motor is discussed. The relation between the hysteresis motor and the synchronous motor is clarified View full abstract»

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