ABSTRACT
This chapter exploes what is meant by operation of a converter in the rectifying and inverting modes. It examines the operation of naturally commutated converters. The chapter addresses the operation of uncontrolled, fully-controlled and half-controlled converters. A half-controlled converter uses a combination of thyristors and diodes enabling control of the direct current (DC) output voltage to be achieved by varying the firing angle of the thyristors. The half-controlled converter is cheaper than a fully-controlled converter of similar rating. A fully-controlled converter uses only thyristors, with control of the DC output voltage determined by the thyristor firing angles. The chapter deals with the general equations describing converter behaviour. It discusses the effect of firing delay and extinction angles on converter performance. The chapter also examines the effect of source inductance on commutation and to define overlap. It highlights the function and operation of the freewheeling diode. The chapter also discusses power factor in relation to a converter circuit.
