Anna University of Technology Tirunelveli 2011 B.Tech Information Technology B.e/ s, /e- - university paper

B.E/B.TECH DEGREE EXAMINATIONS, MAY/JUNE-2011
REGULATIONS 2008
SIXTH SEMESTER
EE 62 SOLID STATE DRIVES
ELECTRICAL AND ELECTRONICS ENGINEERING
Time: 3 Hours Maximum: 100 marks

ans ALL ques.
PART-A(10*2=20 marks)
1. What is dynamic torque in a motor- load system?
2. Draw the load torque- speed characteristics of traction load.
3. elaborate the reasons for discontinuous conduction in a controlled converter fed dc motor drive system?
4. elaborate the advantages of chopper fed dc drive over controlled converter fed dc drive?
5. elaborate the advantages of PI controller.
6. Write down the formula of fundamental rms component of the ac input current.
7. Write down the drawbacks of stator voltage control method.
8. describe unit vector.
9. What is the necessity of delay circuit in open loop v/f control of synchronous motor devices?
10. What is the need of continuous rotor position sensor in self control technique?

Part-B (5*16=80 marks)

11(a)(i) discuss the spped torque characteristics of multi quardant operation in speed torque plane.(8)
(ii) Derive the mathematical condition for steady state stability of equilibrium point.(8)

or

(b)(i) A motor drives 2 loads. 1 has rotational motion. It is coupled to the motor through a reduction gear with a=0.1 and efficiency of 90%. The load has the momentum of inertia of 10Kg-m2 and a torque of 10 Nm. Other load has translational motion and consists of 1000Kg weight of be lifted up at an uniform speed of 1.5 m/s. coupling ranging from this load and the motor has an efficiency of 85%. Motor has an inertia of 0.2Kg-m2 and runs at a constant spped of 1420rpm.Determine equivalent inertia referred to the motor shaft and power developed by the motro?(8)

(ii) discuss the various modes of operation of an electrical drive.(8)

12(a) discuss the continuous and discontinuous conduction modes of operation of three phase fully controlled converter fed separately excited dc motor drive steady state analysis(16)

or

12(b) (i) A 220V, 1500rpm, 11.6A separately excited motor is controlled by a single phase fully controlled rectifier with an ac source voltage of 230V, 50 Hz. Enough filter inductance is added to ensure continuous conduction for and torque, Ra=2ohm. compute the motor speed at the rated torque and a=160 degree for the regenerative barking in the 2nd quadrant(8)
(ii) discuss the control strategies of chopper in detail.(8)

13(a) discuss the step by step procedure of deriving the transfer function of separately excited dc motor load system with armature control.(16)

or

(b) discuss the design procedure of speed controller with 1st order approximation of inner current control loop.(16)

14(a)(i) Make a comparison ranging from star and delta connected ac voltage controller fed stator voltage control method.(8)
(ii) elaborate the reasons for keeping the v/f ratio constant in induction motor drives. (8)

or

(b) discuss the principle of operation of constant air gap flux control technique?(16)

15(a) (i) discuss the concept of open loop v/f control of synchronous motor drive (8)
(ii) write short notes on permanent magnet synchronous motor.(8)

or

discuss self control technique of synchronous motor with constant margin angle control. (16)

Earning:   Approval pending.