Category: DC MOTOR DRIVES

Closed Loop Speed Control of DC Motor

Closed Loop Speed Control of DC Motor: Closed Loop Speed Control of DC Motor – The converters (rectifiers and choppers) are built using semiconductor devices, which have very low thermal capacity. Consequently their transient and steady state current ratings are same. The dc motors can carry 2 to 3.5 times the rated current during transient […]

Chopper Control of Series Motor

Chopper Control of Series Motor: Motoring : Chopper Control of Series Motor and va and ia waveforms will be same as shown in Fig. 5.41. Va is given by Eq. (5.113). However, e is not constant but varies with ia. Due to saturation of magnetic circuit, relationship between e and ia is non-linear. The approximation is already […]

Drawbacks of Rectifier Fed DC Drives

Drawbacks of Rectifier Fed DC Drives: Drawbacks of Rectifier Fed DC Drives are as follows: 1. Distortion of Supply: Source current of a rectifier has harmonics. In a weak ac source, with high internal impedance, current harmonics distort source voltage. Furthermore, temporary short circuit of lines during commutation of thyristors, causes sharp current pulses, which […]

Rectifier Control of DC Series Motor

Rectifier Control of DC Series Motor: Single-phase controlled Rectifier Control of DC Series Motor are employed in traction. A single-phase half-controlled Rectifier Control of DC Series Motor is shown in Fig. 5.37(a). Equivalent circuit of motor is also shown. Since back emf decreases with armature current, discontinuous conduction occurs only in a narrow range of […]

Four Quadrant Drive With Field Reversal

Four Quadrant Drive With Field Reversal: Four Quadrant Drive With Field Reversal as shown in Fig. 5.36, armature is fed from a fully-controlled rectifier and the field from a dual converter so that field current can be reversed. With field current in one direction, the motor operates is quadrants I and IV. When field current […]