Dynamic Characteristics of DC Motor Controlled by Thyristor Chopper Circuit

Abstract

A theoretical method to analyse the steady and dynamic characteristics of a separately excited dc motor controlled by a thyristor chopper circuit is introduced. In the analysis, the influences of the fluctuations of the dc motor speed and the armature current during one cycle of a chopper frequency on the characteristics are considered. The characteristic equation in the control circuit is derived theoretically, and it is then denoted that the circuit performance can be described by an equivalent sampled data system. Next, the validity of the theoretical method is verified by ascertaining that the calculated results agree well with the experimental results. Furthermore, the influences of the circuit parameters and the situation of an armature current on the motor performances are investigated. Finally, the sampled data system is applied to investigate the frequency response of the motor, which has not been investigated in the usual papers.