Power Electronics Viva Questions with Answers
Power Electronics Viva Questions and Answers
 What are the advantages and disadvantages of Flyback converter?
(1) No inductor is required at the output which is compulsory is the other converters topology.
(2) Number of components are less.
(1) Useful for low power applications(50W to 100W)
(2) Output load is compulsory otherwise output capacitance may get overcharge.
 What is meant by Constant Current Source?
A voltage source that has a very high internal impedance as compared with external load impedance is considered as a Constant Current Source( the source which can provide constant current to the load).
 What is the difference between silicon diode and germanium diode?
- Generally Silicon diodes have higher PIV (Peak Inverse Voltage) and current rating than germanium diodes.
- Peak Inverse Voltage (PIV) ratings
for silicon diodes is nearly 1000 V, whereas
for germanium diodes is maximum 400 V only.
- Silicon diodes can work in wider temperature ranges. Temperature range
for Silicon diodes is about 200°C, whereas
for germanium diodes is maximum 100°C.
- The disadvantage of silicon diode is the higher knee voltage (forward-bias voltage required to reach the region of upward swing). Typically the knee voltage
for Silicon diodes is 0.7V, whereas
for germanium diodes is 0.3V.
 What is the difference between Resistor, Rheostat and Potential Divider?
A fixed resistor connected permanently in the circuit for the purpose of limiting the current is called as resistor.
A variable resistance with a sliding contact is known as rheostat. The current flowing through the circuit is restricted by inserting and varying the resistance with the help of the sliding contact.
When a resistance is used to develop a voltage drop, it is called as a potential divider.
 What are the characteristics of ideal Opamp?
- Infinite open loop voltage gain
- Infinite input impedance
- Zero output impedance
- Infinite Bandwidth
- Zero offset voltage
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