How to select SCR, IGBT and MOSFET according to its application? Write brief note for selection of each device.
[3 marks]Explain the principle of step down chopper with the help of circuit diagram and output voltage waveform.
[4 marks]What do you mean by commutation of SCR? Explain the need of commutation in Thyristor circuits. Discuss the commutation scheme employing parallel-resonance turn off with a neat schematic and waveforms.
[7 marks]Freewheeling diode improves the input power factor in phase controlled converter. Justify the statement
[3 marks]Draw the circuit diagram of single-phase half wave controlled rectifier. Also draw the waveform of output voltage and voltage across switch for RL-load with α = 45°. ( Explanation not required )
[4 marks]Explain the working of UJT relaxation oscillator with the help of circuit diagram and waveforms. Derive the expression for frequency of waveform.
[7 marks]Write a short note on various voltage ratings of SCR.
[7 marks]Explain in brief with the help of neat circuit diagram, the use of pulse-transformer in the triggering circuits.
[3 marks]What is the purpose of having parallel operation of SCRs? What care must be taken when paralleling the SCR?
[4 marks]Explain the operation of three phase half wave controlled converter with RL load. Sketch the associated waveforms of output voltage and voltage across any one thyristor for α = 450. Assume continuous conduction.
[7 marks]Snubber circuit for an SCR should primarily consist of capacitor only. But in actual practice, a resistor is used in series with the capacitor. Discuss in brief
[3 marks]What is the necessity of connecting SCRs in Series? What are the problems associated with series connection of SCRs?
[4 marks]Discuss the effect of source inductance on the performance of a single-phase full converter indicating clearly the conduction of various thyristors during one cycle.
[7 marks]State advantages of single phase bridge converter over single phase mid-point converter.1
[3 marks]Enumerates the two merits and two demerits of load commutated chopper
[4 marks]Discuss the working of a current commutated chopper circuit with relevant voltage and current waveforms.
[7 marks]Explain time ration control strategies used for chopper.
[3 marks]Explain with a neat circuit diagram the basic principle of a dual converter.
[4 marks]Discuss the working of a voltage commutated chopper circuit with relevant voltage and current waveforms.
[7 marks]Briefly discuss the role of Power Electronics in industry.
[3 marks]Explain principle of power control for DC motor drive with DC-DC Converter.
[4 marks]Explain single phase fully controlled converter based drive for separately excited DC motor.
[7 marks]State the advantages of three phase controlled rectifier over single phase controlled rectifier for drive system.
[3 marks]IGBT is superior to power BJT and power MOSFET: Justify with advantages.
[4 marks]Using relevant circuit diagram and waveforms, explain regenerative braking control in DC machines using chopper circuit.2
[7 marks]