Power Electronics

What is the basic principle of thyristor operation?

• A thyristor operates continuously without needing a gate current.

• A thyristor operates by being triggered into conduction by a gate current and remains on until the current drops below a certain level.

• A thyristor can only conduct when the voltage is above a certain threshold.

• A thyristor turns off automatically after a fixed time period.

Which is not an example of a static switch

• BJT

• MOSFET

• Inductor

• SCR

A power diode comes under which category

• Uncontrolled devices

• Partially controlled devices

• Fully controlled devices

• Bidirectional current devices

The normalised voltage of a single phase full converter is

Which is not a voltage control method of inverter

• Single Pulse Width Modulation

• Phase displacement control

• Multiple Pulse Width Modulation

• Series Resonant method

Identify a commutation technique used in thyristor circuits?

• Capacitive commutation

• Magnetic commutation

• Inductive commutation

• Natural commutation

How does the gate trigger current affect SCR operation?

• The gate trigger current is used to turn off the SCR.

• The gate trigger current turns on the SCR when exceeded.

• The gate trigger current is irrelevant to SCR operation.

• The gate trigger current only affects the voltage across the SCR.

Which feature is advantageous in using MOSFETs over BJTs in power applications?

• Higher conduction losses

• Slower switching speeds

• Higher input impedance

• Lower input impedance

Differentiate between half-controlled and fully-controlled rectifiers.

• Both half-controlled and fully-controlled rectifiers use only diodes for control.

• Half-controlled rectifiers use diodes and thyristors, while fully-controlled rectifiers use only thyristors.

• Half-controlled rectifiers control both halves of the AC cycle, while fully-controlled rectifiers control one half.

• Half-controlled rectifiers use only diodes, while fully-controlled rectifiers use diodes and thyristors.

the number of terminals for SCR is

• 2

• 3

• 4

• 5