Govt. Exams
Entrance Exams
Snubber circuits limit the rate of change of voltage (dv/dt) across semiconductor switches during switching transients, preventing false triggering and overvoltage damage.
A freewheeling diode provides a discharge path for inductor current when the main switch opens, preventing voltage spikes and ensuring continuous current flow in inductive circuits.
Holding current is the minimum anode current required to keep the thyristor in ON state after the gate signal is removed. If anode current falls below Ih, the device turns OFF.
MOSFETs have switching frequencies up to several MHz, making them ideal for high-frequency applications. Thyristors are limited to lower frequencies (few kHz).
In an ideal chopper, theoretical efficiency is 100% as it transfers energy without dissipation. Practical efficiency is reduced by component losses
A buck-boost converter produces an output voltage of opposite polarity to the input voltage, with magnitude |Vo| = Vin × D/(1-D)
A three-phase full-bridge inverter requires 6 thyristors (2 per phase) to generate three-phase AC output
The freewheeling diode provides a continuous path for the inductor current during the switch OFF period, preventing voltage spikes
A half-bridge inverter requires 2 switches (typically with 2 diodes) to generate AC output from a DC source
A diode conducts only in one direction (forward bias), making it a unidirectional switch
