Your SlideShare is downloading. ×
Dcmachine
Dcmachine
Dcmachine
Dcmachine
Dcmachine
Dcmachine
Dcmachine
Dcmachine
Dcmachine
Dcmachine
Dcmachine
Dcmachine
Dcmachine
Dcmachine
Dcmachine
Dcmachine
Dcmachine
Dcmachine
Dcmachine
Dcmachine
Dcmachine
Dcmachine
Dcmachine
Dcmachine
Dcmachine
Dcmachine
Dcmachine
Dcmachine
Dcmachine
Dcmachine
Dcmachine
Upcoming SlideShare
Loading in...5
×

Thanks for flagging this SlideShare!

Oops! An error has occurred.

×
Saving this for later? Get the SlideShare app to save on your phone or tablet. Read anywhere, anytime – even offline.
Text the download link to your phone
Standard text messaging rates apply

Dcmachine

6,697

Published on

Published in: Education
1 Comment
5 Likes
Statistics
Notes
  • See:
    http://winding.wix.com/design
       Reply 
    Are you sure you want to  Yes  No
    Your message goes here
No Downloads
Views
Total Views
6,697
On Slideshare
0
From Embeds
0
Number of Embeds
4
Actions
Shares
0
Downloads
521
Comments
1
Likes
5
Embeds 0
No embeds

Report content
Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

Cancel
No notes for slide

Transcript

  • 1. Direct-Current Machine
  • 2. Electric Machine
    • Electric machines can be used as motors and generators
    • Electric motor and generators are rotating energy-transfer electromechanical motion devices
    • Electric motors convert electrical energy to mechanical energy
    • Generators convert mechanical energy to electrical energy
  • 3. Electric Machine
    • Electric machines can be divided into 2 types:
        • AC machines
        • DC machines
    • Several types DC machines
        • Separately excited
        • Shunt connected
        • Series connected
        • Compound connected
        • Permanent magnet
  • 4. Electric Machine
    • All Electric machines have:
        • Stationary members (stator)
        • rotating members (rotor)
        • Air gap which is separating stator and rotor
    • The rotor and stator are coupled magnetically
  • 5.
    • Schematic representation of a DC Machine
    DC Machines Stator Rotor + V f - I f I f I f N  f 2 S
  • 6. Electric Machine
    • The armature winding is placed in the rotor slot and connected to rotating commutator which rectifies the induced voltage
    • The brushes which are connected to the armature winding, ride on commutator
  • 7. DC Machines
    • Elementary two-pole DC Machine
  • 8. Electric Machine
    • The armature winding consists of identical coils carried in slots that are uniformly distributed around the periphery of the rotor
    • Conventional DC machines are excited by direct current, in particular if a voltage-fed converter is used a dc voltage uf is supplied to the stationary field winding
    • Hence the excitation magnetic field is produced by the field coils
    • Due to the commutator, armature and field windings produce stationary magnetomotive forces that are displaced by 90 electrical degrees
  • 9.
    • The field winding is placed on the stator and supplied from a DC Source.
    DC Machines Rotor N  f 2 S Armature Winding x x x x x x x x
  • 10. Magnetic Flux in DC machines  f /2 rotor stator I f S N V f + - . . . . . . x x x x x x Armature Winding I f  a
  • 11.
    • The current is induced in the Rotor Winding ( i.e. the Armature Winding ) since it is placed in the field ( Flux Lines ) of the Field Winding.
    DC Machines  f
  • 12.
    • mmf produced by the armature and mmf produced by the field winding are orthogonal.
    Orthogonality of Magnetic Fields in DC Machines B I L F Magnetic field due to field winding Magnetic field due to armature winding 90 o
  • 13.
    • The force acting on the rotor, is expressed as
    DC Machines l f f T e T e = x f l
  • 14.
    • The Field winding is placed on the stator and the current (voltage) is induced in the rotor winding which is referred also as the armature winding.
    • In DC Machines, the mmf produced by the field winding and the mmf produced by the armature winding are at right-angle with respect to each other.
    • The torque is produced from the interaction of these two fields.
    DC Machines
  • 15.  
  • 16.  
  • 17. Transducer with stator and rotor windings
  • 18. Equivalent circuit for separately excited DC motors SEPARATELY EXCITED DC MOTORS
  • 19. Electric Machine
    • Conventional separately excited DC electric machine
        • Stator and rotor windings excited by dc current
        • The rotor has the commutator
        • Dc voltage to the armature windings is supplied through the brushes which establish electric contact with the commutator
        • The brushes are fixed with respect to the stator and they are placed in the specified angular displacement
        • To maximize the electromagnetic torque, the stator and rotor magnetic axes are displaced by 90 electrical degrees using a commutator
  • 20. Electric Machine
    • Electric machine can be either a motor or a generator depending on whether it drives a load or it is driven by a prime mover
    • The direction of the armature current is reversed when an electric machine changes from motor to generator operation
    • However line voltage polarity, direction of rotation and field current are the same
    • ( MOTOR ) If is greater than , the armature current is positive
    • ( GENERATOR ) If is greater than , the armature current is negative
  • 21. Electric Machine
    • Conventional separately excited DC electric machine
        • Using kirchhoff’s second law and assuming the differential equation of a motor
        • In motor application, the output is the angular velocity
  • 22. Equivalent circuit for separately excited DC generators SEPARATELY EXCITED DC GENERATORS
  • 23. Electric Machine
    • Conventional separately excited DC electric machine
        • Using kirchhoff’s second law and assuming the differential equation of a generator
        • The steady state operating condition for a generator are
        • In generator application, the output is the voltage induced
  • 24. DC Machines Energy stored in inductor is stored in the magnetic field within the coil The mutual inductance between the armature and field windings
    • The armature and field magnetic axes are displaced by 90 electrical degrees and the magnetizing reluctance is constant
  • 25. DC Machines
    • The torque equation
    • Electromagnetic power
    • Given that
    • Therefore
    • Electromotive force formula is given as
    • Substituting (2) into (1), yields
    using and Steady state relationship between the angular velocity end electromagnetic torque
  • 26.
    • The DC Machine Dynamic Equations for the circuit represented bellow is
    DC Machines
  • 27. DC Machines
    • The flux linkage equations are:
    Where L ff = field self-inductance L aa = armature self-inductance L af = mutual inductance between the field and rotating armature coils
  • 28. DC Machines - Shunt Connected
    • The Shunt Configuration for a DC Machine is as shown below,
  • 29. DC Machines - Shunt Connected
    • The Dynamic Equations (assuming r f ext = 0 ) are follows,
    Where L ff = field self-inductance L fa = mutual inductance between the field and rotating armature coils e a = induced voltage in the armature coils (also called counter or back emf )
  • 30. DC Machines - Shunt Connected
    • The torque equation for a Shunt Connected DC-Machine is
  • 31. DC Machines - Shunt Connected
    • For DC Machines ,
    mmf field mmf armature + -

×