Direct current electric motors are very common in portable motor equipment such as automobiles and other industrial equipment and toys. The stator of the DC motor provides constant magnetic field. The armature which is rotating part of this motor is consisted coil. This armature is energized through direct current supply.
Working Principle of Direct Current Electric Motors
When current flow into the armature coil, an electromagnetic force induced on the DC motor and the coil will start to rotate.
When the armature coil gets to rotate the commutator rings which connect with the DC power source of the opposite polarity. due to that the electricity of the armature coils always flow away and towards on separate side of the armature coil.
So the torque action is in the same direction through in the motion and coil will continue rotating. There are more loops add into the armature coil to create a smooth rotation of the motor. Those loops are also fit inside with highly permeable steel layers. This will use to enhance the magnetic effectiveness.
Commutator brushes are normally spring-load and this is used to feed supply into the motor. Permanent magnet dc motors are widely used in small motor equipment and applications. Electromagnetic DC motors are widely used for large industrial applications.
The field coil of the electromagnet is also power by the same direct current source of the armature supply.
Normally the field winding is connected to the armature winding of the DC motors on two separate ways such as parallel connection or series connection.
Types of DC Motors
These parallel and series connection create two different type of motor construction inside the motor.
Series Wound Direct Current Electric Motors
Series wounded direct current motor got good starting torque. When the load is applied to motor the speed is getting drop drastically.
Shunt Wound DC Motors
Compare the series wound DC motors shunt wound motors got low starting torque. The speed of this shunt wound motors are constant but when the load add the speed will get reduce
Unlike other motors, this direct current motor produces back emf. this back emf result to reduce the armature current on a large level. Normally back emf is proportional to the speed of the DC Motor. DC motor is also used as a universal motor which got potential to run on both AC and DC power.
Universal motors can able to run under both alternative current (AC) and direct current (DC) power supply. Normally these types of universal motors are used for so many domestic applications like portable drills, blenders, and vacuum cleaners.
As we learn on the Direct current motor this universal motor is DC Series motor which got special arrangement construction.
When this motor is rotated under AC supply speed of the rotor and the frequency the AC supply the torque action of the motor is the same direction. So this motor also run at AC power supply without any problem.
You can’t use DC series motor straight away for AC supply. There are few modifications you need to do for this DC Series motor for better performance.
Since Alternative current rate fluctuating magnetic field inside the motor the resulting eddy current is also getting bigger. So core layer of should laminate for better performance. Contact brushes of the universal motor need to be high resistant.