Special Machine (EX-802 (B)) - Important Questions

Explain the different types of stepper motors, including single-stack and multi-stack, with a neat schematic diagram and working operation.

Explain how to control load angle in a stepper motor.

Discuss speed control methods of stepper motor.

A hybrid variable reluctance stepper motor has 8 stator poles castellated to 5 teeth each and rotor has 50 teeth. Calculate the stepping angle and excitation frequency for a rotor speed of 120 rpm.

Explain the principle of operation of a switched reluctance motor with cross-sectional diagram and state its advantages.

Explain briefly how torque is produced in a switched reluctance motor with expression, and explain shaft position sensing.

Explain the construction and working principle of a brushless DC motor.

Explain series and parallel winding pattern of brushless DC motor.

Explain commutation and armature reaction in a PMBLDC motor.

Compare between soft and hard ferromagnetic materials.

Differentiate between permanent magnet and hybrid stepper motor.

Explain the speed control methods and power controllers used for PMSM with necessary diagrams.

Explain sensorless control of PM synchronous motor.

Explain the construction and operation of a PM synchronous motor.

Write short notes on any two: (i) Motors suitable for electric vehicles (ii) PV-fed water pumping systems (iii) Applications of permanent magnet synchronous motor.