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Large DC motors with separately excited fields were generally used with winder drives for mine hoists, for high torque as well as smooth speed control using thyristor drives. These are now replaced with large AC motors with variable frequency drives. If external mechanical power is applied to a DC motor it acts as a DC generator, a dynamo. This ...
A motor requiring a DC power supply for operation is termed a DC motor. DC motors are widely used in control applications like robotics, tape drives, machines and many more. Separately excited DC motors are suitable for control applications because of separate field and armature circuit. [1] Two ways to control DC separately excited motors are ...
Separately-excited generators like this are commonly used for large-scale power transmission plants. The smaller generator can be either a magneto with permanent field magnets or another self-excited generator. A field coil may be connected in shunt, in series, or in compound with the armature of a DC machine (motor or generator).
A DC motor's speed and torque characteristics vary according to three different magnetization sources, separately excited field, self-excited field or permanent-field, which are used selectively to control the motor over the mechanical load's range. Self-excited field motors can be series, shunt, or a compound wound connected to the armature.
In vector control, an AC induction or synchronous motor is controlled under all operating conditions like a separately excited DC motor. [21] That is, the AC motor behaves like a DC motor in which the field flux linkage and armature flux linkage created by the respective field and armature (or torque component) currents are orthogonally aligned such that, when torque is controlled, the field ...
Batteries are direct-current (DC) devices, so an EV's power electronics include a DC-AC inverter to provide the stator with the AC current necessary to create the all-important variable RMF.
The intermediate DC circuit's voltage variation is automatically taken into account in the algorithm (in voltage integration). Thus no problems exist due to dc voltage ripple or dc voltage transients; Synchronization to rotating machine is straightforward due to the fast control; Just make the torque reference zero and start the inverter. The ...
Doubly fed generators are another solution to this problem. Instead of the usual field winding fed with DC, and an armature winding where the generated electricity comes out, there are two three-phase windings, one stationary and one rotating, both separately connected to equipment outside the generator.