Difference Between DC Motor vs. AC Motor

Main Difference

More often than not people are confused about the difference between AC and DC motor while even professionals are sometimes unsure about the utilization of these two types of motors. The primary function of both types of motors is same, and they work to provide the same output. There is no comparison between the two as both have their own uses but the main difference to simplify what separates the two is that AC motors are the ones run by alternating current while DC motors are operated by direct current. There is also alterations in the way both these motors work and what kind of devices they are suitable for. AC motors are better for small scale services which do not require a significant output while DC motors are mostly used for more major applications as they can work better for such functions. Both are used to control the speed of the system, in the case of AC motors, this is done by changing the frequency of the electricity being supplied to the system, while DC motors the speed of system depends on the direct voltage that is applied. Ac motors cost more while DC motors are easy to manufacture. There are two main types of AC motors named as induction motors and synchronous motors. For DC motors, there are four different kinds which are called Permanent magnet stator, electromagnetic wound stator, shunt and compound motors. AC Motors have their own advantages such as giving acceleration in a controlled manner, the speed and torque can be changed according to the requirement and has low power requirement in the beginning. DC motors, on the other hand, are used in many toys and other industrial objects such as machines, vehicles, and other significant items. They are also of an advantage since their speed is controlled easily with the help of winding and can also be installed quickly. Both types of motors have their own benefits and drawbacks, but they are being used in various fields because of unique characteristics.

Comparison Chart

DC MotorAC Motor
UsageUsed for large scale applicationsUsed for small scale applications
PowerVariable in large rangebetween 1 to 100 Watts.
StructureComplexSimple
Productive RatioDC motors are cheaper but are heavier in comparison and are larger in sizeAC motors are more expensive but have a structure which is lighter

Definition of AC Motor

There are two main parts of an AC motor known as a stator and rotor. The stator is the stationary part that has coils around it which create a magnetic field with the help of this, the rotor moves when the torque is applied. There are other components of AC motor including bearing, frame, and winding which assist in the working. The two types of motors work on their own principles. Induction motor uses the rotor, and the magnetic field which is created by the help of induced current, this type of motor is also known as an asynchronous motor. The second type of motor, synchronous, does not depend on induction and uses the frequency of the rotor and the magnetic field which in this case is formed with the help of permanent magnet and have a faster speed as compared to the induction motor. There are no brushes and springs in these types of motors which save some maintenance costs.

Definition of DC Motor

There are six main parts of a DC motor which are rotor, stator, commutator, axle, magnetic field and brushes. Its primary function is to produce mechanical energy with the help of current provided. The magnetic field is created with the support of two powerful agents present at both ends. The stationary part of the motor is known as a stator which has the magnetic field and two magnets along with the casing. The axle and commutator help the rotor to rotate according to the magnetic field from the stator. The commutator is attached to the stator with the aid of winding through which electricity flows. When the current is applied, due to the difference in the extreme values of winding and magnets the rotor moves along with the stator causing the motor to perform its functions. Different types of motors for DC work differently according to the requirements, but the basic principle stays the same. The presence of springs and other components increase the cost in some respect and the sizes are greater.

Differences in a Nutshell

  1. AC motors are used for small scale applications where the output is between 1 to 100 Watts. DC motors, on the other hand, are used for bigger applications and to get a greater power output.
  2. The efficiency of AC motors is less as compared to DC motors and ranges around 10 to 20%. DC motors usually have higher efficiency.
  3. The structure of an AC motor is simple, but the structure of a DC motor is more complicated.
  4. AC motors do not have to be checked for maintenance regularly and have greater stability, but DC motors have to be maintained properly because of the presence of a commutator and are less stable.
  5. AC motors have a more complicated control structure while DC motors can be monitored easily.
  6. AC motors are more expensive but have a structure which is lighter, better and efficient. DC motors are cheaper but are heavier in comparison and are larger in size.

Comparison Video

Conclusion

Most of the people have a general idea about what a motor is, but they are usually lost for words when it comes to going into the detail of the types. AC and DC motors are the two basic ones which give people a headache when they want to explain them. This article, however, makes things easier by explaining the two types in simple way.