# DC motor

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## DC-motor

Using the DC motor the speed and torque can easily be controlled and therefore these type of motor is built in all sizes. These motors are used in precision engineering or in large machines with a power supply of 1500 V and an output power of more than 10,000 kW.
Permanent magnet-excited motors are used for smaller power and are primarily used in automotive engineering as windscreen wiper, blower or servo motors. In industry, you find these motors in machine tools, conveyor systems or rolling mills. Furthermore, they are used in local trains as a part of the drive system.

### How a DC motor works

The following video is to discuss the functioning of an DC motor. From the content:

• How a DC motor gets its torque
• Flemings Left Hand Rule
• Reverse the direction of a DC motor

• 0:00 Introduction DC motors
• 0:29 How torque can be created
• 1:50 Permanent Magnet DC (PMDC)
• 3:00 Controlling with H-Bridge
• 4:46 Series DC motor
• 7:36 DC Shunt motor
• 9:26 Others (Compound DC motor, Universal motor)

#### Have a closer look at the operating principle:

Operating principle of a DC-motor

A torque is built up via the electrodynamic law. Hereby a force acts on a current-carrying conductor loop within the magnetic field:

F = I * L * B

In addition, we can see that a current-carrying conductor is surrounded by a circular magnetic field. A force on the conductor loop is created by superposition of the external magnetic field (generated by the field magnet) and the internal magnetic field (generated by the conductor loop).

!  How must a motor be dimensioned mechanically so that a large torque can be built up?