As the commutator rotates it connects and disconnects these segments through the brushes, applying power to different pairs of segments. To fix this we use the commutator, which is a conductive copper sleeve around the axle of the rotor, physically and electrically divided into segments. That’s all very well but if we just used regular wires to connect the rotor windings to the power supply, once the rotor has turned far enough its magnetic force would effectively reverse direction – so the rotor would just move back and forth, instead of rotating in one direction. The stator can be a permanent magnet or electromagnet, depending on the requirements of any particular application. When we send current through the rotor windings, the field generated interacts with the stator's field and creates the force that turns the rotor. The rotor consists of one or more windings of wire wrapped around a core made of a ferrous metal, usually iron, and connected to power with a metal ‘brush’. This interacts with the primary magnetic field to create an opposing force that moves one part of the motor, usually causing it to rotate around an axle.īrushed DC motors consist of four key components the stationary magnet (called a stator), the rotor, the commutator and the brushes (see Figure 1). The current flowing through the wire generates the second magnetic field. It does this through the interaction between magnets, one of which is typically created by passing a current through wire bound around a ferrite core. Going back to basics, the fundamental principle of an electric motor is, of course, that it converts electricity into motion. We’ll also introduce brushless DC motors and their pros and cons. In this article, we’ll explain the basics of brushed DC motors, and then look at the circuitry required to drive them. Brushed motors are lower cost and are simpler to drive, so they remain a popular option. More recently, brushless DC motors have become increasingly popular but for many applications brushed DC motors are still the right choice. By David Birks, Applications Engineer, Diodes IncorporatedĭC electric motors have been around for nearly two hundred years, with a steady series of refinements in that time.
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