This document provides information about single phase DC motors, including: 1) It defines a DC motor as a machine that converts direct current into mechanical power and describes the basic components of a DC motor including the stator, rotor, yoke, poles, field winding, armature winding, commutator, and brushes. 2) It discusses the history of the DC motor, including the invention of the first commutator-type DC motor in 1832 and the first practical DC motor in 1886. 3) It covers various topics related to DC motors such as efficiency, speed regulation, torque-speed characteristics, back EMF, types of DC motors including permanent magnet, series, shunt,

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A DC motor is any of a class of electrical machines that converts direct
current electrical power into mechanical power. The motor that has
1 phase winding in stator field and fed from a single phase dc
supply, is known as Single phase DC motor.
The first commutator-type direct current electric motor
capable of turning machinery was invented by the British
scientist William Sturgeon in 1832.
In 1886 Frank Julian Sprague invented the first practical DC
motor, a non-sparking motor capable of constant speed under
variable loads.
A DC motor is a machine that deals in the conversion of electrical energy to mechanical
energy and this is essentially brought about by two major parts required for the construction
of dc motor, namely.
1) Stator: The static part that houses the field windings and receives the supply. And,
2) Rotor: The rotating part that brings about the mechanical rotations.
Other than that there are several subsidiary parts namely the
3) Yoke
4) Poles
5) Field winding
6) Armature winding
7) Commutator
8) Brushes
All these parts put together configures the total construction of a dc motor.
GREEN UNIVERSITY OF BANGLADESH
DEPARTMENT OF EEE
Single Phase DC Motor
Definition & History
Efficiency: Commercial or Overall efficiency (ηc) is defined as the ratio of mechanical power
out (c); by Electrical power in.
i.e. ηc = Mechanical Power Out (c) / Electrical Power In (A)
ηc = Mechanical Power Out (c) / VIa
SPEED REGULATION: The speed regulation of a rotor is the change in speed from full-load
to no-load and is expressed as a percentage of the speed at full load.
i.e. % speed regulation = { ( N0 – N ) / N } X 100
Construction
Principle
Principle: Whenever a current carrying conductor is placed in a magnatic field, it experiences a
force due to the magnatic field.
Fleming’s left hand rule: When the thumb, index finger, and the middle finger of
left hand are stretched perpendicular to each other; If the force finger represent
the direction of magnatic field, the middle finger represent the direction of current
then the thumb represent the direction of force.
How Rotor Rotate:
F = BI (Newton)
Back EMF: When the armature of a dc motor rotates under the influence of the driving torque,
the armature conductor move through the magnatic field and hence emf is induced in them, the
induced emf acts in opposite direction of the applied volyltage (lentz's law) and known as back
emf or counter emf.
Equation:
Classification
There are four types of DC motor. Those are-
1. Permanent Magnet Motor
2. 2. Series Motor 3. Shunt Motor
Eb = VT – Ia ( Ra + Rse ) Eb = VT – IaRa
4. Compound Motor
a) Long Shunt b) Short Shunt
Eb = IshRsh – IaRa Eb = VT - Ia ( Rse + Ra )
Characteristic Carve (Ta Vs. Ia )
Electric Electric
Power
Mechanical
Power Cu
Losses
Developed Iron and
Friction
Losses
Power
Input In Armature Output
Power Stages
Series = Ta ∞ Ia
2 Shunt = Ta ∞ Ia Compound = Ta ∞ ΦIa
2
Speed Control
N ∞ Eb / Φ
N = k {( V – Ia-R ) / Φ } ; where R = Ra + Rse
Therefore, speed of a DC motor can be controlled by :-
1. Flux Control Method: by varying the flux per pole Φ.
2. Armature Control Method: by varying the resistance in the armature ckt.
3. Voltage Control Method: by varying the applied voltage V.
4. Ward Leonard Method.
5. Series Parallel Method.
6. Multiple Method.
Application
1. Shunt Motor: It is a constant speed motor. Where the speed is required to remain almost
constant from no-load to full-load. Where the load has to be driven at a number of speeds and
any one of which is nearly constant. Industrial use:
a) Lathes Drills, b) Boring mills, c) Shapers Spinning and d) Weaving machines
2. Series Motor: It is a variable speed motor. The speed is low at high torque. At light or no-
load, the motor speed attains dangerously high speed.bThe motor has a high starting torque.
Industrial Uses:
a) Electric traction, b) Cranes, c) Elevators, d) Air compressor, e) Vacuum cleaner,
f) Hair drier, g) Sewing machine
3. Compound Motor: Compound motors are virtually suitable for almost all applications like
business machines, machine tools, agitators and mixers etc. Compound motors are used to
drive loads such as shears, presses and reciprocating machines.
Prepared By:
143010021 Md. Sahed Dewan 143010023 Sakib Abdul Ahad 143010024 Most Champa Khatun
143010027 Zisan Ahmed 143010031 Md. Nurullah Al Kawser 143010032 Md. Zahedul Islam
143010034 Saddam Hossain 130101084