# EE6601 Solid State Drives Important Questions

**UNIT I**

**1. Derive the mathematical condition for steady state stability.**

**2. Briefly explain about the four quadrant operation of electric drive. (Or) Explain in detail**

**about multi quadrant operation of low speed hoist drive with neat diagram.**

**3. (a) Explain about all three modes of operation of electric drive.**

**(b) Briefly explain about types of braking of electric drive.**

**4. (i) Briefly analyze the load torque characteristics for all types of load.**

**(ii) Explain about the different classes of motor duty.**

**(iii) Explain about load equalization and derive the expression for moment of inertia of flywheel.**

**5. Describe the torque equation governing the motor load dynamics.**

**UNIT II**

**6. Describe the operation of single phase fully controlled rectifier control of separately excited**

**DC motor and obtain the expression for motor speed for continuous and discontinuous modes**

**of operations.**

**7. Explain the motoring and braking operation of three phase fully controlled rectifier control**

**of DC separately excited motor with aid of diagrams and waveforms(for a = 30°, 600, 90°,**

**120°, 150°, 180°). Also obtain the expression for motor terminal voltage and speed.**

**8. (i) Explain in detail about CLC and TRC methods.**

**(ii) Explain about the Ward —Leonard method of speed control of DC motor.**

**9. Explain the operation of four quadrant DC chopper.**

**10. Explain the operation of a two quadrant chopper fed DC drives.**

**UNIT III**

**11. Derive the transfer function of separately excited DC motor and load.**

**12. Explain in detail about design of speed controller and current controller. (Or) Describe the**

**closed loop speed control of separately excited DC motor by proportional controller. (Or)**

**Explain the current limit control of separately excited DC motor.**

**13. Write short notes on : (i) Field weakening mode control, (ii) Armature voltage control**

**14. Explain in detail about converter selection and characteristics?**

**15. Explain in detail the use of simulation software packages with flowchart.**

**UNIT IV**

**16. Explain in detail about Vector control of induction motor drive.**

**17. (i) Explain the operation of constant air gap flux control.**

**(ii) Explain the operation of constant slip speed control.**

**18. Explain the induction motor operation when the V / f ratio is held constant also derive the**

**expression for maximum torque?**

**19. Draw and explain the slip power recovery scheme applicable for three phase slip- ring**

**induction motor.**

**20. Using a diagram and speed- torque curve, explain the stator voltage control scheme for**

**the speed control of a three phase induction motor.**

**UNIT V**

**21. (i) Explain with the block diagram of marginal angle control of synchronous motor drive.**

**(ii) Explain Power factor control of synchronous drive.**

**22. (i) Describe the self control of synchronous motor.**

**(ii) Explain the operation of open loop (V/f) control / separate control of multiple synchronous**

**motors with Schematic diagram?**

**23. Explain the closed loop control system of adjustable speed synchronous motor drives.**

**24. Explain the construction and operation of permanent magnet synchronous motor.**

**25. Explain how three phase synchronous motor fed by a three phase inverter can be made to**

**behave like a simple DC motor. Hence is it proper to call them as a commutator less DC motor.**

**(Or) Explain in detail about the brushless DC motor drive.**

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