Power Electronics – I — Winter 2022

Draw only circuit diagram and write only output voltage equation of a buck-boost chopper.

Draw only circuit diagram and waveforms of 1-ph asymmetric semi converter.

Explain Class-Ccommutation of SCR.

What is the significance of drift layer (n-) in Power Diode?

Compare R, RC and UJT triggering circuits.

Explain the principle of regenerative braking.

Explain the operation of 1-ph full-wave phase controlled rectifier with Rload, with necessary waveforms. Derive the equation of average output voltage.

Draw only circuit diagrams with all the required notations:

1-ph half-wave converter (ii) 1-ph half-bridge converter

Draw only circuit diagrams with all the required notations:

Two transistor model of SCR (ii) Class-Dcommutation of SCR

Explain step down chopper and derive the output voltage equation.

With reference to series connected SCRs:

What is string efficiency? (ii) What is derating factor? (iii) How system reliability varies with string efficiency? How system reliability varies with derating factor?

Briefly explain rectification mode and inversion mode of AC to DC converter.

What is continues conduction mode and discontinues conduction mode of operation of a chopper?

Explain 3-ph fully controlled converter based DC drive.

What is the difference between regenerative braking and rheostatic braking? Draw only circuit diagram of rheostatic brake control in DC drive. 1/2

Why a DC to DC converter is called “chopper”? Classify various DC choppers.

Explain static equalizing circuit required for series connected SCRs.

Enlist all the methods

to turn on SCR (ii) to trigger gate of SCR

Give difference between voltage commutated chopper and current commutated chopper.

Explain the principle of operation of Power MOSFET.

Why isolation is provided between control circuit and power circuit? Enlist all the possible methods of isolation.

Draw only vertical structure and V-Icharacteristic of IGBT.

Explain the principle of operation of 1-ph dual converter. 2/2