SYNCHRONOUS MOTOR DRIVE QUESTION BANK

1.    Explain the self controlled  mode of operation of a synchronous motor                            

2.    Explain constant margin angle control technique of self controlled synchronous motor drive employing load commutated thyristor inverter.                                                    

3.     Discuss the advantages  and disadvantages of margin angle control                              

Advantages:

i) The commutation failure is prevented.

 ii) The maximum power output can be increased by simultaneous control of the field current to compensate for armature relation

iii) There is improvement in the power factor

iv) the torque pulsations under light load conditions are reduced. Also the ripple content of the dc link current decreases.

Disadvantages:

The main disadvantage is limited speed range. To avoid this the margin time is specified and it is kept constant.

4.    Briefly explain the types of PMSM                                                                                  

5.    Explain the vector control  of sinusoidal  SPM in constant torque region                      

6.    A 3 phase 400 V , 50 hz, 6 pole , a star connected  round  - rotor synchronous motor has Zs = 0+j2 Ω . Load torque, proportional to speed squared, is 340 Nm at rated synchronous speed.  The speed of the motor is lowered by keeping V/F constant and maintaining unit PF by field control of the motor. For the  motor operation  at 600 rpm, calculate i)  supply voltage ii)  armature current iii) excitation angle  iv) load angle  v) pull out torque .  Neglect rotational losses.                                                                    

7.    Brief about  trapezoidal PMAC motor drive                                                                    

8.    Explain the open loop V/F control  of synchronous motor drive                                    

9.     Explain the construction and working of permanent magnet synchronous Motor.     

10.  What is meant by commutatorless DC motor?                                                              

11.  Write in detail about power factor angle control of synchronous motors.                       

             With neat block diagram, explain the variable frequency control of multiple synchronous                          motors.