Title :
A Static Variable-Frequency Three-Phase Source Using the Cycloconverter Principle for the Speed Control of an Induction Motor
Author_Institution :
Department of Electrical Engineering, California State Polytechnic College, San Luis Obispo, Calif. 93401.
Abstract :
This paper describes a variable-frequency source employing the cycloconverter principle. SCR´s have been used as the principal switching and voltage-regulating devices. The logic of the firing circuit has been discussed. The factor affecting output frequency stability has also been presented. A three-phase variable low-frequency oscillator has been used as the reference to achieve the variation of frequency. Voltage variation has been affected by phase delaying of the firing pulses in a manner similar to that in a phase-controlled rectifier. Provision has been made for changing the phase sequence at the output in order to facilitate reversal of the direction of rotation of the motor. Experimental results include output waveforms of various frequencies (0-30 Hz), and speed variations of the experimental motor (1 hp, 100 V, 1700 r/min) in either direction of rotation thereby providing the practical feasibility of the SCR cycloconverter for speed control of induction motors.
Keywords :
Circuit stability; Delay; Frequency; Induction motors; Logic circuits; Logic devices; Oscillators; Rectifiers; Velocity control; Voltage;
Journal_Title :
Industry Applications, IEEE Transactions on
DOI :
10.1109/TIA.1972.349776