in an electric drive, a multiposition noncontact switch in which semiconductor devices (diode, transistor, or thyristor) serve as working elements. Motor drive controllers are widely used as a replacement for the commutator-and-brush apparatus in electric machines. Diodes and transistors are used for low-power machines, and thyristors are used for high-power machines. Motor drive controllers are reliable and have a high switching speed (more than 1 million per second). An electric motor drive controller circuit equipped with thyristors (1–6) is shown in Figure 1.
In an electric valve motor the armature winding is located on the stator and the field winding is located on the poles of the turning rotor. Direct current is fed to the armature winding through the thyristors in such a way that at any moment one thyristor from the cathode group and one from the anode group are conducting, so that electric current flows continuously through two phases of the armature winding. The frequency of thyristor switching determines the speed of rotation of the motor shaft.
REFERENCES
Beskontaktnye elementy i sistemy telemekhaniki s vremennym razdeleniem signalov. Moscow, 1964.Tikhmenev, B. N., and L. M. Trakhtman. Podvizhnoi sostav elektricheskikh zheleznykh dorog, 3rd ed. Moscow, 1969.
IU. M. IN’KOV
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