What are the different excitation methods for DC motors?
The power supply method for the excitation winding is called the excitation method. The excitation methods for DC motors include the following:
(1) Separately excited type. The field winding of a separately excited DC motor is powered by another power source and is not connected to the armature winding. Permanent magnet DC motors also belong to this category because the main magnetic field of a permanent magnet DC motor is established by a permanent magnet and is independent of the armature current.
(2) Shunt-wound type. The excitation winding and armature winding are connected in parallel. The excitation current of the DC motor with this connection is related to the voltage across the armature.
(3) Series winding. The field winding and armature winding are connected in series.
(4) Compound-wound DC motor. A compound-wound DC motor has both shunt and series windings, both wound on the same main pole core. In this case, the magnetomotive forces of the shunt and series windings can be added or subtracted; the former is called cumulative compound winding, and the latter is called differential compound winding. The shunt winding can be connected to the armature using either a solid line or a dashed line; the former is called short-term compound winding, and the latter is called long-term compound winding. In fact, there is little difference in operating performance between long-term and short-term compound-wound DC motors; only the current in the series winding is slightly different.
