The Discontinuous Conduction Mode

Abstract

When the ideal switches of a dc-dc converter are implemented using current-unidirectional and/or voltage-unidirectional semiconductor switches, one or more new modes of operation known as discontinuous conduction modes (DCM) can occur. The discontinuous conduction mode arises when the switching ripple in an inductor current or capacitor voltage is large enough to cause the polarity of the applied switch current or voltage to reverse, such that the current- or voltage-unidirectional assumptions made in realizing the switch with semiconductor devices are violated. The DCM is commonly observed in dc-dc converters and rectifiers, and can also sometimes occur in inverters or in other converters containing two-quadrant switches.