Electric Drives and Their Control

Q.1. (a) Explain the multi-quadrant operation of an electric motor driving a hoist load. Also discuss the different modes of operations of an electric drive. [8]

(b) Explain steady state stability. What is the main assumption? [8]

Q.1. (a) Explain the load equalization in electric drive. [8]

(b) What are the advantages and disadvantages of electric drives? [8]

Q.2. (a) Explain the dynamic braking of DC separately excited motor with speed torque characteristics. [8]

(b) What are the power limitations in armature voltage control in DC drives? [8]

Q.2. (a) Discuss operation of a dual converter in different modes, feeding a separately excited DC motor drive. [8]

(b) A 200V, 10.5A, 2000 rpm shunt motor has the armature and field resistance of 0.5 ohm and 400 ohm respectively. It drives a load whose torque is constant at rated motor torque. Calculate motor speed if the source voltage drops to 175V. [8]

Q.3. (a) Explain plugging braking for induction motor. What are the advantages and disadvantages of electric braking? [8]

(b) Explain the stator voltage control for speed control of induction motor. [8]

Q.3. (a) What are the advantages of the variable frequency control of induction motor drives? Explain the variable frequency speed control scheme. [8]

(b) Write short note on operation of Voltage Source Inverter (VSI). [8]

Q.4. (a) Explain the slip recovery scheme with Static Kramer Drive. [8]

(b) Explain using a power circuit, how the speed of an induction motor drive can be controlled by using current source inverter. [8]

Q.4. (a) Explain the slip power recovery scheme with Stator Scherbius Drive in brief. [8]

(b) Explain static rotor resistance control of induction motor drive. [8]

Q.5. (a) Explain the regenerative braking of synchronous motor with VSI. [8]

(b) Explain the control characteristic of an open loop V/f controlled synchronous motor. [8]

Q.5. (a) Describe the VSI fed self-controlled synchronous motor drive. [8]

(b) Write a short note on dynamic braking of synchronous motor with VSI. [8]