By Topic

Electric Power Applications, IEE Proceedings B

Issue 2 • Date March 1985

Filter Results

Displaying Results 1 - 10 of 10
  • DC traction motor with slotless armature

    Page(s): 61 - 71
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1191 KB)  

    The slotless armature concept is an attempt to overcome the problem of poor commutation in DC traction motors. A small (90 hp) motor has been fitted with such an armature and has undergone tests to investigate the properties of slotless armature motors in the areas of commutation, eddy-current loss and mechanical stress under electrical-fault conditions. It is verified that commutation is markedly improved by adopting a slotless winding. Satisfactory agreement is found between measured and predicted no-load loss, including eddy-current loss; however, it is found that the eddy-current loss could be unacceptable if the armature conductors are not divided into two or more insulated strips. A model representing the machine under fault conditions predicts armature currents in reasonable agreement with test results. However, the model also predicts that all practical designs of slotless traction motor will suffer a shear stress of up to about 2 MN/m2 between winding and core if subjected to a sudden short circuit. Further work is needed to find an insulating system with a good margin of strength in excess of this figure. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Multilayer analysis of electromagnetic systems incorporating layers of discrete conductors

    Page(s): 72 - 76
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (498 KB)  

    The paper presents the development of an electromagnetic model which represents an array of discrete conductors in a form suitable for use with the multilayer method of analysis of electromagnetic systems. The multilayer technique is thereby extended in scope to cover an important class of problems concerning eddy current effects in machine windings. The model employs the concepts of magnetic equivalent circuits incorporating transference to construct an equivalent network. This is reduced by network analysis to a simple transformation of magnetic fluxes and scalar potentials. The transformation is subsequently modified to relate field rather than network quantities so that it can be employed in multilayer analysis. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Filter design for multiphase DC choppers

    Page(s): 77 - 80
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (370 KB)  

    Normalised equations for ripple voltage and currents are derived in terms of dimensionless quantities, and these equations can be used directly to evaluate the values of LC-filter components, taking into consideration the effect of the load current ripple on the RMS value of the chopper-generated line current ripple. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Phase-angle control of the repulsion/drive force ratio in two-phase linear induction motor with nonferromagnetic secondary

    Page(s): 81 - 86
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (582 KB)  

    The repulsive/drive force ratio in a two-phase linear induction motor with a nonferromagnetic secondary can be changed over a wide range by changing the stator field from a travelling to a pulsating field. This can be achieved by controlling the phase angle between the two-phase currents of the stator. The stator electric loading of the unbalanced two-phase current system is derived, including the space harmonics due to the stator winding distribution. The magnetic field analysis is carried out on a three-region model using the magnetic vector potential. The force components acting on the conducting secondary sheet are calculated using Maxwell's stress tensor. The drive and suspension force components are plotted as functions of the slip, with the phase angle between the two-phase currents as parameter. The effect of the harmonic force components is also investigated. The induced voltages in the stator winding are determined, the stator voltage equations are established, and the corresponding locus diagrams are constructed for different values of the phase angle. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Microprocessor control of a `hidden-link¿ convertor drive

    Page(s): 87 - 92
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (968 KB)  

    This synchronous motor drive, unlike the DC link convertor drive, has a single mode of operation from starting to above synchronous speeds. The simple control scheme requires synchronism to the supply waveforms and rotor position. Hardware, software and interface circuits for a Z80 microprocessor-based controller are described. A modest clock rate of 2.5 MHz is sufficient and still leaves the microprocessor 88% idle. High levels of control, and possibly some diagnostic features, can therefore be included. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Chopper control of DC disc-armature motor using power MOSFETs

    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (789 KB)  

    A closed-loop current controller using power MOSFETs has been constructed for two-quadrant chopper control of a DC disc armature motor intended for use in an electric cycle. Theoretical analysis shows that lower energy requirements and higher efficiency are obtained using constant current, rather than voltage, control, and that approximately 30% of the energy expended in accelerating to maximum speed would be available for regeneration. The practical difficulties of using MOSFETs for motor control are discussed, and experimental results are presented which agree well with the theory. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Frequency-response identification of a linear helical reluctance motor

    Page(s): 101 - 105
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (499 KB)  

    The paper describes a frequency-response-identification method using a dedicated microprocessor. Although the detailed results discussed are with particular reference to the linear helical reluctance motor, the method is generally applicable to electrical machines. A linear incremental model is obtained based on the describing-function technique for a range of load-angle values. Magnetic saturation effects are taken into account and a frequency-limitation parameter is defined in connection with motor synchronism. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Adaptive microprocessor control of a linear helical reluctance motor

    Page(s): 106 - 111
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (570 KB)  

    It has been shown previously that open-loop control, using a dedicated microprocessor, achieves a very satisfactory dynamic and static performance. However, this performance is only valid provided that output inertia and load torque do not vary. This paper extends the work to closed-loop operation in which a nonlinear sampled-data feedback controller is proposed. It is found that the resulting system resolution is inferior to that achieved with open-loop control and leads to the concept of two-mode control with open-loop control operating at input displacement demands below ±1°, to achieve good resolution. Finally an adaptive controller is implemented to cope with wide variation of load mass of about three times the rotor mass. Optimum dynamic resolution is of the order of ±0.25° (¿ ± 3× 10¿3m). View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Helical motion induction motor

    Page(s): 112 - 114
    Save to Project icon | PDF file iconPDF (325 KB)  
    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Book review: Power Electronics and Variable-Speed Drives

    Save to Project icon | PDF file iconPDF (170 KB)  
    Freely Available from IEEE