Electric Propulsion

Question 1

Discuss some reasons that might be given to justify the use of electric propulsion despite the extra complexity.

Answer 1

Low noise and vibration, good for structure and passengers/crew, good for oceanography ships and warships.
High power to weight ratio, smaller Diesel engine.
Less emissions, renewable energy less diesel.
Can store energy, batteries electric flywheels etc.
Ease of control, through variable frequency, increase thrust by changing shaft speed.
Layout, engine room wherever, no shaft limiting, good for nav arch and performance enhancing.

Question 2

Give some disadvantages of a cycle converter

Answer 2

Max frequency is only 1/3 of supply frequency.

Harmonics.

Question 3

Give some disadvantages of a synchro converter

Answer 3

Has to operate with synchronous motor. High harmonic content.

Question 4

Give som advantages of a synchro converter.

Answer 4

4 quadrant motor operation. Output frequency can be varied from 0 to supply frequency.

Question 5

Give the equation for V in a shunt motor in armature terms

Answer 5

V=IaRa+E

Question 6

Give the equation of V in a shunt motor in field terms

Answer 6

V=IfRf