Govt. Exams
Entrance Exams
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
For a boost converter, Vo/Vin = 1/(1-D). With D=0.5, Vo = 12/(1-0.5) = 24V
The motor inductance tends to maintain current flow. The freewheeling diode provides a path for this current when the main switch is off, preventing voltage spikes.
Sinusoidal PWM produces a voltage waveform containing the fundamental frequency plus high-frequency harmonics that can be filtered out.
Turn-off time (tq) determines the minimum period required between successive gate pulses, thus limiting the maximum operating frequency of thyristors.
A buck converter steps down the input voltage. The output voltage Vo = D×Vin where D is the duty cycle (0 < D < 1), making output always less than input.
