DC motor is the electrical machine that converts DC electrical energy into mechanical energy. In this article you will get dc motor working principle and construction detail explanation.
construction of dc motor
Stator : stator is the stationery part of DC motor it will remain fix at one place it will not move or rotate. stator core is made up of laminated Silicon Steel that supports magnetic field lines due to high permeability property .
Frame : frame is also known as yoke that supports the stator core and protect the internal assembly of the DC motor , it provides easy path for magnetic flux that will produced by field winding placed on field pole. Outer frame of DC Motor is made up of cast steel .
Pole : poles are present at the inner portion of a stator where field winding remain placed . This portion of pole is known as pole shoe that supports the field coil . DC motor working principle also reducing the reluctance of magnetic path by increasing the area , due to more space reluctance of magnetic path get reduced .
Field winding : field winding place on field pole at inner portion of a stator core.
Armature : armature is the rotating part of DC motor , armature core is also made up of laminated soft Steel lamination is the arrangement of various thin sheets were all lamination sheets are insulated by the coating of varnish and clamped together. Armature of motor is also known as roto that placed on shaft . Insulated copper conductor place on the outer portion of armature. That play very important role in the DC motor working principle and it is known as armature winding. To insulate the winding varnish material is used we provide coating on armature winding
there are two type of windings are used on armature that is either lap winding or wave winding
Commutator : commutator is the important part of armature that behave like mechanical rectifier. Carbon brushes are attached with commutator. We give dc supply in armature by the help of commutator and carbon brushes. Commutator is the copper segment where each segment is connected to end of the armature coil. Construction of DC motor is just like DC generator but working of both machine is different. DC motor convert DC electrical energy into mechanical energy while DC generator converts mechanical energy into DC electrical energy
dc motor working principle
First of all we give DC supply to the field winding that place on stator pole so due to DC supply and inductive copper winding constant magnetic field produces.
and as well as we innergize the armature winding with DC supply through commutator and carbon brushes . So according to working principle of DC motor from lorentz law “whenever current carrying conductor placed in magnetic field conductor experience electromagnetic force in tangential direction” here also current carrying armature is placed in magnetic field produced by field winding so torque acts on the armature conductor in tangential direction and armature starts to rotate where direction of rotation is determined by Fleming left hand rule .
commutator and brushes plays very important role in dc motor working principle , it reverse the current at half rotation so that armature rotate in same direction. This is dc motor working principle
Back EMF in dc motor
during operation of DC motor when armature cuts the stationery magnetic field then EMF induces due to generator action where produced back EMF opposes the supply voltage . When are major
rotates and cuts the constant magnetic field produced by field winding self EMF induces in the armature conductor from Faraday’s law of electromagnetic induction. And induced EMF opposes the supply voltage.
magnitude of back EMF is given by
Eb = NPØZ/60 A
- Eb – back emf
- A – number of parallel path
- P – number of poles
- N – speed of armature
- Z – total number of conductor in armature
Applications
- DC Motors are used in lifting equipment specially DC shunt motor they are used in Elevators and lifts because they have a smooth speed control and constant speed characteristics.
- DC motor is used in steel and paper mills due to their high torque and smooth speed control ability.
- this type of electric motors are used in conveyor belts robotics and other automation system due to their good performance that we have already discussed in dc motor working principle
- DC Motors are used in pumps and compressors in various industrial application including hydraulic system climate control system and chemical processing.
- in dc motor working principle we have already discussed how DC Motors work smoothly so they are used for metal cutting machines.
- DC Motors are used in electric vehicles and hybrid cars where it act as primary power source in electric vehicles and it provide regenerative breaking in hybrid cars.
- DC motor is used in cooling fan windshield wipers
- DC Motors are used in Robotics renewable energy sources for solar energy tracking wind turbine blade adjustment or for battery charging.
- these Motors are used in household appliances like fans electric toothbruses and hair dryer also it is used in medical equipments in portable medical devices.
Advantages
- DC motor can produce high level of torque or high starting torque this property makes them ideal for that type of application where need of quick acceleration and heavy loads.
- we can easily control the speed of DC motor by controlling applied voltage or current so we can say it have simple speed control.
- DC motor operates precisely that makes it suitable for the application of robotics and and Industrial automation.
- it has less maintenance required and easy to install there are not need of skilled person to install DC motor.
- DC motor is more suitable for that type of application where requirement of high torque at low speed.
- According to requirement DC motor can quickly response so we can say it have fast response time.
Disadvantages
- More expensive to manufacture DC motor especially that uses commutator and brushes, compare to AC motor DC motor have more components that make it expensive.
- compare to AC motor DC motor has more Complex structure and requirement of maintenance due to commutator and brush assembly.
- it have requirement of Replacement the commutator and brushes over periods of time. Due to rany wea and tear we have to replace carbon brushes and commutator that make it costly.
- DC motor – VIDEO