Analysis of an AC-DC Full-controlled Converter Supplying Separately Excited DC Motor Parallel with Series DC Motor Loads

Controlled rectifiers are widely used as a source of DC motors power supply. It is important to study motor characteristics when fed from such converters. Early work has studied single motor characteristics when fed from a converter. This paper is concerned with the study of an AC-DC full-controlled converter supplying separ- ately excited DC motor parallel with series DC motor loads. Continu- ous and discontinuous converter currents are considered. The critical firing angle is deduced. The margin firing angle that separates motor operation from generator operation of the separately excited machine is investigated. The performance characteristics have been derived and studied for each of: constant firing angle, constant torque of the separately excited motor and constant horsepower of the series motor. Waveforms for each load current and converter current are investigat- ed for different modes of operation.