please send me the ppt on two quadrant chopper for controlling the speed of dc motor

http://seminarprojectsimages/smilies/confused.gif

The basic principle of the DC motor is a device which converts DC energy into mechanical energy. When the current carrying armature is connected to the supply end though commentator segment, brushes are placed within the North South Poles of permanent or electromagnets. By using these electromagnets operating principle is depends on the Fleming’s left hand rule to determine the direction of the force acting on the armature conductors of the DC motor.

Speed Control Methods of a DC Motor

Speed of a DC motor can be varied by varying flux, armature resistance or applied voltage. Different speed control methods for different DC shunt and series methods are there.

Speed Control of Shunt Motors

Flux control method
Armature and Rheostatic control method
Voltage control method
Multiple voltage control
Ward Leonard system
Speed Control of Series Motors

Flux control method
Field diverter
Armature diverter
Trapped field control
Paralleling field coils
Variable Resistance in series with motor
Series -parallel control method
Flux Control Method

In this flux control method, speed of the motor is inversely proportional to the flux. Thus, by decreasing flux and speed can be increased vice versa. To control the flux , he rheostat is added in series with the field winding will increase the speed because of this flux will decrease. So, the field current is relatively small and hence I2R loss is decreased. This method is quite efficient.