← All revision guidesSEMESTER 6 · 4360905
6FLASHCARDSElectrical Drives
Drive selection, motor control, braking and converter-fed operation.
Drive dynamics
Q1What are the main parts of an electrical drive?
A supply, power modulator, motor, load, sensing elements and control unit form the drive system.
Q2State the drive acceleration equation.
Accelerating torque equals motor torque minus load torque, and is equal to J multiplied by angular acceleration.
Q3What is four-quadrant operation?
It describes forward and reverse motoring and braking, according to the signs of speed and torque.
Control and braking
Q1What is regenerative braking?
The motor develops braking torque while operating as a generator and returns electrical energy to the source.
Q2Why is V/f kept approximately constant in an induction-motor drive?
It maintains air-gap flux near its rated value below base speed and avoids saturation or torque loss.
Q3What does a closed-loop speed drive add to an open-loop drive?
It measures actual speed, compares it with the command and corrects the error through feedback control.