Power Electronics – I — Summer 2023

What is snubber circuit? Explain working and application for same.

ExDpilfafeinre wntoiartkei nNga otufr asel rCieosm cmonuntaetciotend a SndC RFosr. ced Commutation.

Differentiate Natural Commutation and Forced Commutation.

Explain working of parallel connected SCRs.

CoDmifpfearreen ptioatwe eNr aMtuOraSl FCEoTmsm wuittahti oBnJ Tans.d Forced Commutation.

Give at least five applications of phase controlled rectifiers.

Draw and explain the working of an UJT oscillator. Discuss how the amplitude of output voltage pulse can be estimated in this oscillator.

Draw circuit diagram, waveform and derive expression for Vfor 3-phase RMS full wave converter with R-Lload.

Explain function of freewheeling diode in mid-point full wave rectifier.

Explain pulse transformer in detail.

Explain continuous and discontinues conduction operation of choppers.

Draw circuit diagram, waveform and derive expression for Vfor 3-phase RMS half wave converter with Rload.

Explain the need for protection of semiconductor power devices. Explain di/dt and dv/dt protection of SCR.

Explain Morgan’s chopper.

Draw and explain RC triggering circuit for SCR.

Write brief note on buck-boost converter.

Describe Synchronized UJT Relaxation Oscillator for triggering of SCR with circuit diagram.

What is chopper? Explain step-down chopper.

Give block diagram for closed loop speed control of DC drive. Explain working of each block.

Explain basic concept of principle for speed control of DC motor.

Explain CUK converter.

Explain Principle of power control of separately excited motor with DC-DC Converter.

Explain 1-phase dual convertor drive in short.

What is regenerative braking? Explain w.r.t DC motor.

Explain operation of four quadrant DC motor using chopper circuit.