DC motor: the device, the work, the use of

paper discusses in this article unit depends entirely on the phenomenon of electromagnetic induction.This is a basic principle of the DC motor.It is generally known that the conductor with a current passing through it placed in the area of ​​the magnetic field exerts a force which can be determined in accordance with the left-hand rule: F = B * I * L, where -electric current I, B - induction field;L - the calculated length.Crossing the lines of magnetic force, the conductor becomes an electromotive force, which is in relation to the flow of current is directed against him, and called the reverse, or counter.DC motor converts mechanical power in the form of energy, but also part of its spending on heating.

On the surface of a mechanical device unit can be seen as follows: DC motor structure is relatively simple, it is represented by the inductor and the armature, which are isolated by an air gap.

inductor creates a stationary magnetic field of the machine and, in turn, consists of a frame, the pole

(main and supplementary).Pole mounted on the frame, and the substrate itself is involved in the magnetic circuit unit.The main pole of the field winding include creating a magnetic field, and the extra - coil to improve the connection.

DC motor is equipped with an anchor from separate sheets, coils of wire and a collector (fitted on the shaft cylinder of copper plates).Material removal is carried out using the current brush.They are fixed and are retained in a specific position that provides the required pressing force to the surface of the collector.

During DC motor moves the brush on the surface of circulating collector in such a way that they are constantly moving from one plate to the other.Since switching the parallel sections of the coil and the armature current are changed.The process, as well as phenomena associated with it, is called switching.EMF is an additional current, which has a non-uniform distribution of energy density on the surface of the brush.That is what is the main cause of sparking collector (the intensity of this phenomenon is estimated quality grading is determined by the switching and its degrees).

DC motor is able to undergo the excitement - the creation in it of a magnetic field required in the operation of the device.They are divided into four groups (by the method of excitation):

  • Independent, which coil is powered by an external source of direct current.
  • Parallel - winding is connected in parallel source of the armature coil.
  • consistent - consistently included.
  • Mixed (with serial and parallel excitation coils).

At first start-up anchor stationary and the battery voltage is equal to zero.Resistance is small, so the starting current can be 10-20 times higher than the rated.To ensure a smooth start-up resistor is used step, the resistance of which is elected for a possible starting current of the motor.