DC motor, how it works?
- Machine tools
- Air compressors
- Motor starters in cars
How a DC motor actually works
The rotor is normally located on the inside of the motor, while the stator is located on the outside. The rotor contains coil windings that are powered by the DC current and the stator contains either permanent magnets or electromagnetic windings. When the motor is powered by DC current, a magnetic field is created within the stator, attracting and repelling the magnets on the rotor. This causes the rotor to start rotating.
To keep the rotor rotating, the motor has a commutator. When the rotor aligns with the magnetic field, it would stop spinning, but in this case the commutator would reverse the current through the stator and this way reverse the magnetic field. This way the rotor can keep spinning. See the image on the right for a schematic display of how the dc motor works.
Four types of Direct Current (DC) motors
There are four types of DC motors. All four types work in roughly the same way, as a Direct Current motor always consists of two main parts: a rotor and a stator.
- Permanent Magnet DC motor
- Series motor
- Shunt motor
- Compound motor
Advantages and disadvantages of a DC motors
When it comes to starting and regulating speed, brushed DC motors have a good performance. The torque density is relatively high for these motors. A Direct Current motor runs smoothly and the range of speed regulation is wide. The overload capability is strong and the electromagnetic interference is small. A disadvantage of the DC motor is the structure. There is a sliding contact between the commutator and the brush. This causes sparks and mechanical wear. Direct Current motors have relatively short life expectancy because of this and the motor has high maintenance cost. It also raises reliability concerns.