Speed control of a DC series motor using a modulated phase-angle controlled single triac

A strategy which involves replacing the integral-cycle controlled triac with a modulated phase-angle controlled triac is explained, and the associated motor performance characteristics are determined. This control strategy combines the advantages of integral-cycle and phase-angle controlled drives. The firing circuit necessary for this method of triac triggering is developed and is used to verify theoretical validity of the proposed control strategy experimentally. The motor current is unified using a rectifier bridge. The mathematical model describing the performance of the motor in the different modes of operation is given. Saturation in iron parts, iron losses, mechanical losses, and the dependence of the motor inductance on the motor current are considered. Good agreement is found between the theoretical and experimental results