Experimental Approach to DC Chopper with a Minimum Triggering Level Mode of Thyristor

Abstract

As is well known, a DC chopper using a single thyristor is operated with the variable-frequency TRC (time ratio control) system. However, this system has the disadvantage that the control range in load voltage is limited. From this point of view, therefore, we propose the new method for DC chopper which utilizes a minimum triggering level mode performance of the thyristor. If our proposed method is used, a constant-frequency system can be operated with the square-wave control signal in a wide range of the load voltage.
In this paper, the operating principle and the steady state analysis of this system are described. In addition, the temperature compensation for this chopper is discussed with some experimental results. The chopper was applied to control the speed of a DC series motor. From the experimental data, it is clear that the chopper was operating stably to the inductive and counter-emf loads.