4 Types of DC Motors and Their Characteristics

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DC Motor Characteristics

As you already know, there are two electrical elements of a DC motor, the field windings and the armature.The armature windings are made up of current carrying conductors that terminate at a commutator. DC voltage is applied to the armature windings through carbon brushes which ride on the commutator.

4 Types of DC Motors and Their Characteristics
4 Types of DC Motors and Their Characteristics (on photo: Incline Conveyor 72″ Long 7″ Wide 90 Volt DC Motor; credit:

In small DC motors, permanent magnets can be used for the stator. However, in large motors used in industrial applications the stator is an electromagnet.

When voltage is applied to stator windings an electromagnet with north and south poles is established. The resultant magnetic field is static (non-rotational).

For simplicity of explanation, the stator is represented by permanent magnets in the following illustration.

DC Motor Construction
DC Motor Construction

The field of DC motors can be:

  1. Permanent magnet (Permanent magnet stator),
  2. Electromagnets connected in series (Wound stator),
  3. Shunt (Wound stator), or
  4. Compound (Wound stator).

Let’s see the basics of each type as well as their advantages and disadvantages.

1. Permanent Magnet Motors

Permanent Magnet Motors
Permanent Magnet Motor

The permanent magnet motor uses a magnet to supply field flux. Permanent magnet DC motors have excellent starting torque capability with good speed regulation. A disadvantage of permanent magnet DC motors is they are limited to the amount of load they can drive.These motors can be found on low horsepower applications.

Another disadvantage is that torque is usually limited to 150% of rated torque to prevent demagnetization of the permanent magnets.

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2. Series Motors

Series DC motor
Series DC motor

In a series DC motor the field is connected in series with the armature.The field is wound with a few turns of large wire because it must carry the full armature current.

A characteristic of series motors is the motor develops a large amount of starting torque. However, speed varies widely between no load and full load. Series motors cannot be used where a constant speed is required under varying loads.

Additionally, the speed of a series motor with no load increases to the point where the motor can become damaged. Some load must always be connected to a series-connected motor.

Series-connected motors generally are not suitable for use on most variable speed drive applications.

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3. Shunt Motors

DC Shunt Motor
DC Shunt Motor

In a shunt motor the field is connected in parallel (shunt) with the armature windings. The shunt-connected motor offers good speed regulation. The field winding can be separately excited or connected to the same source as the armature.

An advantage to a separately excited shunt field is the ability of a variable speed drive to provide independent control of the armature and field.

The shunt-connected motor offers simplified control for reversing. This is especially beneficial in regenerative drives.

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4. Compound Motors

Compound DC motor
Compound DC motor

Compound motors have a field connected in series with the armature and a separately excited shunt field. The series field provides better starting torque and the shunt field provides better speed regulation.

However, the series field can cause control problems in variable speed drive applications and is generally not used in four quadrant drives.

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DC Motor – Explained (VIDEO)

Cant see this video? Click here to watch it on Youtube.

Reference: Basics of DC Drives – SIEMENS (Download)

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About Author


Edvard Csanyi

Edvard - Electrical engineer, programmer and founder of EEP. Highly specialized for design of LV/MV switchgears and LV high power busbar trunking (<6300A) in power substations, commercial buildings and industry fascilities. Professional in AutoCAD programming. Present on