PPT - DC Machines | Electrical Machines - Electrical Engineering (EE) PDF Download

 Page 1


DC Machines
Page 2


DC Machines
Direct Current (DC) Machines Fundamentals
? Generator action: An emf (voltage) is induced in a
conductor if it moves through a magnetic field.
? Motor action: A force is induced in a conductor
that has a current going through it and placed in a
magnetic field.
? Any DC machine can act either as a generator or
as a motor.
Page 3


DC Machines
Direct Current (DC) Machines Fundamentals
? Generator action: An emf (voltage) is induced in a
conductor if it moves through a magnetic field.
? Motor action: A force is induced in a conductor
that has a current going through it and placed in a
magnetic field.
? Any DC machine can act either as a generator or
as a motor.
Simplest rotating dc machine
? It consists of a single loop of
wire rotating about a fixed axis.
? The rotating part is called rotor,
and the stationary part is the
stator.
? The magnetic field for the
machine is supplied by the
magnetic north and south poles.
With uniform air gap, the
reluctance is same under the
pole faces.
Page 4


DC Machines
Direct Current (DC) Machines Fundamentals
? Generator action: An emf (voltage) is induced in a
conductor if it moves through a magnetic field.
? Motor action: A force is induced in a conductor
that has a current going through it and placed in a
magnetic field.
? Any DC machine can act either as a generator or
as a motor.
Simplest rotating dc machine
? It consists of a single loop of
wire rotating about a fixed axis.
? The rotating part is called rotor,
and the stationary part is the
stator.
? The magnetic field for the
machine is supplied by the
magnetic north and south poles.
With uniform air gap, the
reluctance is same under the
pole faces.
The Voltage Induced in a Rotating Loop
? If the rotor is rotated, a
voltage will be induced in the
wire loop.
? The voltage on each segment
is given by eind =(vxB).l
? The total induced voltage on
the loop is: eind =2vBl
Page 5


DC Machines
Direct Current (DC) Machines Fundamentals
? Generator action: An emf (voltage) is induced in a
conductor if it moves through a magnetic field.
? Motor action: A force is induced in a conductor
that has a current going through it and placed in a
magnetic field.
? Any DC machine can act either as a generator or
as a motor.
Simplest rotating dc machine
? It consists of a single loop of
wire rotating about a fixed axis.
? The rotating part is called rotor,
and the stationary part is the
stator.
? The magnetic field for the
machine is supplied by the
magnetic north and south poles.
With uniform air gap, the
reluctance is same under the
pole faces.
The Voltage Induced in a Rotating Loop
? If the rotor is rotated, a
voltage will be induced in the
wire loop.
? The voltage on each segment
is given by eind =(vxB).l
? The total induced voltage on
the loop is: eind =2vBl
The Voltage Induced in a Rotating Loop
? When the loop rotates
through 180°,
?segment ab is under
the opposite pole face
?the direction of the
voltage on the
segment reverses
?its magnitude remains
constant
The resulting voltage e
tot