What Is the Difference Between AC Motors and DC Motors?

Electric motors are used in almost every industry and in a wide range of applications. Electric motors are available in a wide range of sizes and types. These motors can be selected based on their functioning, voltage, and applications. Using the proper motor with high-quality parts and performing regular maintenance keeps your motor running smoothly and protects endpoint equipment from wear and power spikes.

This article discuss about the major differences between the AC and DC motor.


Electric motor is a machine which converts electric energy into mechanical energy usually by employing electromagnetic phenomena. It works on the principle that when a current-carrying conductor is placed in a magnetic field, it experiences a mechanical force whose magnitude is determined by F = BIl Newton and whose direction is determined by Fleming’s Left-hand Rule.

The various types of electric motor differ in the ways in which the conductors and the field are arranged and also in the control that can be exercised over mechanical output torque, speed, and position. The following are the two main types of electric motors:

  • AC motors, which are powered by alternating current
  • DC motors, which are powered by direct current

Electric motors are available in a wide range of sizes and types. These motors can be selected based on their functioning, voltage, and applications. 


An electric motor is a device used to convert electricity into mechanical energy which is opposite to an electric generator. The field winding and the armature winding are two key components of every motor. The field winding’s primary role is to generate a fixed magnetic field, whereas the armature winding resembles a conductor organized within the magnetic field. They work on the basis of electromagnetism, which states that when an electric current is present in a magnetic field, a force is applied. This force produces a torque on the armature winding in the magnetic field, which causes the armature on the rotor or stator to rotate around the shaft.


An alternating current is required for the AC motor to rotate. Using electromagnetic induction, this motor transforms alternating current to mechanical power. Magnetic fields generated by coils wrapped around the output shaft provide energy to an AC motor. AC motors are efficient, long-lasting, quiet, and adaptable, making them a suitable option for a variety of power generation applications.

The stator, or fixed outer drum, and the rotor, or revolving inner section coupled to the motor shaft, are the two primary components of an AC motor. Rotating magnetic fields are generated by the stator and rotor The winding of the stator that creates the rotating field is created by alternating current.

When an AC supply flux is connected to the stator, an air gap is generated, which rotates the flux at a fixed synchronous speed, producing voltages in the stator and rotor winding.

DC Motor:

In DC Motors,Direct current electric energy is converted into mechanical rotational energy. You can also utilize the device in reverse to generate DC electrical power by turning a motor shaft (making the device function as a generator). 

The winding connections, in which the two coils in the motor are coupled to each other, can be used to classify DC motors.A magnetic field is formed in the stator of a DC motor when it is turned on. The field causes the rotor to rotate by attracting and repelling magnets on the rotor. The commutator, which is hooked to brushes connected to the power source, supplies current to the motor’s wire windings to keep the rotor revolving.

What is the Difference Between AC and DC motors?

DEFINITIONAn electrical machine that converts AC electrical energy into mechanical energy.An electrical machine that converts DC electrical energy into Mechanical energy.
TYPEThere are two main types of AC motors; Asynchronous (Induction) motor & Synchronous motor.There are two main types of DC motor; Brushed DC motor & Brushless DC (BLDC) motor
CURRENT INPUTOperated on Alternating currentMostly operates on DC current. In case of DC series motor, the motor might run with AC supply
INPUT SUPPLY PHASE AC motors can run on both single phase and three phase suppliesDC Motors are single phase having two lines as input (positive and negative)
COMMUTATOR & BRUSHESIn Ac motor, Commutators and brushes are absentIn DC motor, Commutators and carbon brushes are present
STARTING OF MOTORA three-phase AC motor is self-starting but the single phase AC motor requires a starting mechanismDC motors are always self-starting in nature
ARMATURE CHARACTERISTICSarmature is stationary while the magnetic field rotatesThe armature rotates while the magnetic field remains stationary.
INPUT TERMINALThree input terminals- RYBTwo input terminal- positive and negative
SPEED CONTROLIts speed is controlled by varying the input frequency. It uses VFD for controlling their speedIts speed is controlled by varying armature current. It is easier to control externally through PWM
LOAD CHANGESAC motors show a slow response to the change in loadDC motors show a quick response to the change in load
LIFE EXPECTANCY Since AC motors do not have brushes and commutators, they are very rigged and have a high life expectancyThe brushes and commutators in DC motors limit the speed and reduce the life expectancy of the motor
EFFICIENCYAC motor has relatively low efficiency due to the induction current lossesDC Motor has high efficiency because the magnetic field is generated by a permanent magnet
TorqueThe torque decreases with an increase in speedIt requires frequent & costly maintenance. thus they are costlier than AC
MAINTENANCEIt requires less maintenance & is cost-effectiveIt requires frequent & costly maintenance. thus they are costlier than AC
APPLICATIONSAC motors are required where there is a need for high speed and variable torqueDC motors are required where there is a need for variable speed and high torque
PRACTICAL USESUsed in large industries.Mostly used in small domestic appliances.

Hope, this blog helps you to understand the actual difference between AC and DC motor. We will be back with more informative blogs soon.

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