Operation

Typically, electric motors run by electromagnetism. However, there are also other types of motors that utilize electrostatic forces or piezoelectric effect. In the case of a PMDC motor, motion is produced by an electromagnet (armature) interacting with a fixed field magnet (housing assembly). Electrical current flows through the motor terminals in the endcap assembly that comes in contact with the commutator in the armature assembly through the carbon brushes or brush leaves. The electrical current powers the coils generating a magnetic field causing the armature to rotate as it interacts with the magnets encased in the housing assembly. Flemming’s Left Hand Rule helps to determine the direction of the force, the current and the magnetic flux.

3 Key Elements Interacting to Produce Motion

1. Magnetic Flux – The motor housing which contains the permanent magnets generate a magnetic field with the core or lamination stack forming a path.
2. Current – When electricity is applied across the motor terminals, current flows through from one end of the terminal to the brush, commutator then to the windings, back to the commutator and brush and out through the other terminal.
3. Force – The current that flows through the magnetic field then produces an electromagnetic force that causes the shaft to rotate. As conductor rotates to opposite pole, the commutator switches the direction of the current and continuously causes the shaft to rotate. This continuous switching of current produces the rotating force. This generated rotating force is called torque and this is usually measured at the shaft.