Electric Drives — Summer 2022

Draw speed torque characteristic of DC separately excited, shunt and series motor with proper labeling.

Enlist methods for speed control of DC motor. Explain any one in brief.

Describe four quadrant operation of a dc motor.

Give of comparison between converter fed dc drives and chopper fed dc drives.

Explain dynamic model of DC motor drive.

Explain chopper controlled DC shunt motor drive operation for motoring mode and regenerative mode.

Adc chopper is used for regenerative braking of a separately excited dc motor. The dc supply voltage is 400 V. The motor has r =0.2 Ω, a k =1.2V-s/rad. The average armature current during regenerative m braking is kept constant at 300 Awith negligible ripple. For a duty cycle of 60% for a chopper, determine: (a) power returned to the dc supply

equivalent load resistance of motor acting as a generator (c) minimum and maximum permissible breaking speeds and (d) speed during regenerative braking.

Draw the circuit and waveform of 1-ɸ dual converter drive for the speed control of separately excited dc motor.

Explain the closed loop speed control technique for DC motor.

Discuss chopper controlled Separately excited DC motor drive operation for motoring mode.

Define the principle of vector control.

Compare DC Drive with AC Drive.

Explain closed loop speed control of induction motor using slip control scheme.

Discuss the points to be considered while selecting carrier frequency for inverter.

Compare VSI with CSI fed induction motor drives.

Draw and explain block diagram of CSI variable frequency drive with current control.1

List advantages of V/f control over scalar control.

Discuss effect of various harmonic torques of VSI based induction motor drive.

Explain the feature of PWM inverter fed Induction motror drive.

Explain the effect of non-sinusoidal supply on VSI.

Explain stator voltage control of induction motor.

Explain constant air gap flux control scheme for induction motor drives.

Explain operation of doubly fed induction machine in sub synchronous mode.

Compare scalar control and vector control.

Apply the slip recovery scheme for speed controlling of induction motor drive.