Final answer:
Inductors can operate in DCM, BCM, or CCM modes, characterized by current waveforms that either fall to zero, just touch zero, or remain non-zero throughout the switching cycle, respectively. Voltage applied to an inductor in an AC circuit leads the current by a 90° phase angle.
Step-by-step explanation:
When discussing inductors operating in different modes within electronic circuits, it is important to understand the three main modes: Discontinuous Conduction Mode (DCM), Boundary Conduction Mode (BCM), and Continuous Conduction Mode (CCM). Each mode describes different operational characteristics and behaviors of inductors in response to changing currents and voltages.
Concerning the waveforms for these modes in inductors:
- DCM occurs when the current through the inductor falls to zero during part of the switching cycle. The current waveform will have a positive portion during the on-time, followed by a decay to zero and a period where it remains at zero until the next cycle begins.
- BCM is a transitional mode between DCM and CCM where the inductor current just touches zero before the next cycle starts. The waveform looks similar to that of DCM, but the current returns to positive just as it reaches zero.
- CCM is characterized by the inductor current never reaching zero within the switching cycle. The waveform will show a continuous sine wave like pattern, with both the positive and negative phases of the cycle being non-zero.
The operation of inductors in AC circuits involves the relationship between voltage and current where the applied voltage leads the current by a 90° phase angle or one-fourth of a cycle. The effect of an inductor's opposition to change in current is expressed through inductive reactance, which can be thought of as a type of AC resistance.