The basic principle of operation of a cycloconverter can be explained with reference to an equivalent circuit shown in Fig.1. Each two-quadrant converter is now represented as an alternating voltage source, which corresponds to the fundamental or wanted voltage component generated at its output terminals. The diodes connected in series with each voltage source shows the unidirectional conduction of each two-quadrant converter. If the ripple in the output voltage of each converter is neglected, then it becomes ideal and represents the desired output voltage.

The basic control principle of an ideal cycloconverter is to continuously modulate the firing angles of the individual converters, so that each produces the same sinusoidal a.c. voltage at its output terminals. Thus, the voltages of the two generators in Fig.1. have the same amplitude, frequency and phase, and the voltage at the output terminals of the cycloconverter is equal to the voltage of either of these generators. It is possible for the mean power to flow either "to" or "from" the output terminals, and the cycloconverter is inherently capable of operation with loads of any phase angle, within a complete spectrum of $360^{\circ} .$

Because of the unidirectional current carrying property of the individual converters, it is inherent that the positive half-cycle of load current must always be carried by the positive converter, and the negative half-cycle by the negative converter, regardless of the phase of the current with respect to the voltage. This in its means, each two-quadrant converter operates both in its rectifying and in its inverting region during the period of its associated half-cycle of current.