Unit - 3

Induction Motor Drives I

Q1) With the help of neat block diagram, explain the closed loop speed control of self controlled synchronous motor drives fed from VSI.

Q2) With the help of neat block diagram, explain the closed loop speed control of self controlled synchronous motor drives fed from CSI.

Q3) What is the selection criterion for motors? How ratings of the motor subjected to variable load duty is decided?

Q4) Write in brief about topology, control and applications of AC servo motor drives.

Q5) What is the V/f control strategy? Explain with necessary diagram V/f control method using power control devices.

Q6) A drive has following parameters: J=10 kg-m2 , T = 100-0.1N, N-m, passive load torque T1= .05N, N-m, where N is speed in rpm. Initially the drive is operating in steady state. Now it is to be reversed. For this motor characteristics is changed to T= –100-0.1N, N-m. Calculate the time of reversal.

Q7) Explain closed loop control speed control of DC motor with inner current control loop. How below and above speed control is obtained.

Q8) Explain DC dynamic braking in detail.

Q9) Write short note on: Plugging and regenerative braking.

Q10) Compare VSI and CSI.

Q11) Find motor phase current if dc link current is 10mA.