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PROGRAM ROZWOJOWY

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SRMs do, however, offer some advantages along with potential Iow cost. For example, they can be very reliable machines sińce each phase of the SRM is largely independent physically, magnetically, and electrically from the other motor phases. Also, because of the lack of conductors or magnets on the rotor, very high speeds can be achieved, relative to comparable motors.

Power ratings of SRMs, ranges from a few watt to practically MW units for Iow speed control rangę Iow dynamics, as well as high grade (servo) applications, especially in thermally and chemically harsh environments.

1.1. CONSTRUCTION AND FUNCTIONAL ASPECTS

The basie operating principle of the SRM is quite simple; as current is passed through one of the stator windings, torąue is generated by the tendency of the rotor to align with the excited stator pole (reluctance torąue is produced by the tendency of the rotor to move to its minimum reluctance position —Figi. 1).

a)    b)

Fig. 1.1. Magnctic field distribulion in the cross-seelion of SRM forced by the phase eonstant current for: a) non align (by 30°) rotor position. b) align rotor position.

The direction of torąue generated is a function of the rotor position with respect to the energized phase, and is independent of the direction of current flow through the phase winding. Continuous torąue can be produced by intelligently synchronizing each phase’s excitation with the rotor position.

By varying the number of phases m, the number of stator poles N_s (N_s = 2mq - each phase is madę of concentrated coils placed on 2q stator poles), and the number of rotor poles N_r, many different SRM geometries can be realized. A few examples are shown in Fig. 1.2.

UNIA EUROPEJSKA

EUROPEJSKI FUNDUSZ SPOŁECZNY

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Materiały dydaktyczne dystrybuowane bezpłatnie.

Projekt współfinansowany ze środków Unii Europejskiej w ramach Europejskiego Funduszu Społecznego

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