20-12-2012, 06:20 PM
SWITCHED RELUCTANCE MOTORS
1SWITCHED RELUCTANCE.ppt (Size: 1.8 MB / Downloads: 31)
INTRODUCTION
Pple of stepper motor; magn material suspended in magn field align in direction of field due to torque
Basically stepper motor;i.e rotate through fixed angle [step angle] when input pulse is applied
Speed proportional to pulse frequency; pulse<200Hz-discrete rotation and pulse>16KHz-continous rotation
When step angle decreases,num of steps / rev increases
Stepper motors:#sr motors #pm motors #hybrid motors
PRIMARY CHOICE FOR SERVO APPLICATIONS
SIMPLE MOTOR CONSTRUCTION AND POWER CONVERTER MADE IT ATTRACTIVE ALTERNATIVE TO INDUCTION MACHINES
LIKE AC MACHINES,SRM DONOT REQUIRE COMMUTATOR AND BRUSHES
HIGH PEAK TORQUE,POWER DENSITY,TORQUE INERTIA RATIO
VARIABLE SPEED MACHINE
CONSTRUCTION
STATOR AND ROTOR ARE SALIENT IN STRUCTURE
STATOR WINDINGS ARE INDEPENDENT CONCENTRATED WINDINGS WHICH ARE EXCITED WITH SWITCHES FROM SOURCE
NO FIELD WINDINGS HENCE SINGLY EXCITED
DIAMETRICALLY OPPOSITE ARMATURE WINDINGS ARE CONNECTED TO FORM A PHASE
FOR BIDERCTIONAL CONTROL AND SELF STARTING,NUM OF ROTOR POLES ARE LESS THAN NUM OF STATOR POLES
M15,M17,M19 FOR HIGH SPEED AND HYPERCO AND VANADIUM PERMENDUR FOR HIGH PERFORMANCE
SINGLE STACK AND MULTI STACK CONSTRUCTION POSSIBLE
WORKING
FIG SHOWS AN 8/6 SINGLE STACK WHICH HAS 4 PHASES A,B,C,D
WHEN PHASE A IS EXCITED RELUCTANCE TORQUE CAUSES ROTOR TO TURN UNTIL IT ALIGNS WITH AXIS OF PHASE A.
EXCITATION IS CHANGED TO B AND A IS DEEXCITED BEFORE ALIGNMENT
ROTATION IS IN DIRECTION OF ENERGISATION
DIRECTION OF ROTATION REVERSED BY REVERSING SEQUENCE OF EXCITATION
SPEED DEPENDS ON MAGNITUDE OF INPUT
MICROSTEPPING CAN BE DONE
FOR SINGLE STACK ONLY 1 ROTOR AND STATOR