Speed Control of a D.C. Series Motor Using Field-Parallel Connected Thyristor Chopper

With the rapid progress of power electronics, the thyristor chopper technique has been successfully used in the speed control of a d.c. series motor. In such a speed control system, the thyristor chopper is generally connected in series with the armature or the field winding, and with this series connection the motor can not be operated at a mode of regenerative braking.In this paper, we consider a new speed control system which has the thyristor chopper connected in parallel with the field winding and also has an auxilliary diode bridge circuit in order to rectify the field current. In this system, the motor, is controlled by only one thyristor chopper at the power running mode as well as at the regenerative braking mode.We analyze the speed-torque characteristics of the above mentioned system and discuss the dynamic performances theoretically and experimentally.