SUBJECT CODE : EE6703

SUBJECT NAME : Special Electrical Machines

STAFF NAME : Mr.U.Nagabalan

INTRODUCTION

SYNCHRONOUS RELUCTANCE MOTOR -

- It is similar to the salient pole synchronous machine except that the rotor does not have any field winding.

RELUCTANCE TORQUE -- The tendency of the salient poles to align themselves in the minimum reluctance position.

FLUX BARRIER -- It is another approach is to use laminations. The lamination required for the shaft weaken the rotor .It is used for low speed design.

AXIAL AIR GAP MOTOR -- It is another approach is to use laminations. The torque ripple and iron losses are more in axially laminated rotor than radiallylaminated.

INTRODUCTION

EXPLOSION BONDING -- First sheets of

ferromagnetic and nonmagnetic steel are bonded .The

bonded sheets are then cut into rectangular blocks which

are the machined into the desired rotor.

SALIENT ROTOR -- Salient rotor shape such that

the quadrature air gap is much larger than the direct air

gap. It is used for high speed application.

CONSTRUCTION OF SYNCHRONOUS

RELUCTANCE MOTOR

CONSTRUCTION OF SYNCHRONOUS

RELUCTANCE MOTOR

The stator has three phase symmetrical

winding, which creates sinusoidal rotating

magnetic field in the air gap.

Reluctance torque is developed because the

induced magnetic field in the rotor has a

tendency to cause the rotor to align with the

stator field at a minimum reluctance position

CROSS SECTIONAL VIEW OF

SYNCHRONOUS RELUCTANCE

MOTOR

CROSS SECTION OF AXIALLY

LAMINATED

CROSS SECTION OF RADIALLY

LAMINATED

CONSTRUCTION OF SYNCHRONOUS

RELUCTANCE MOTOR

ROTOR DESIGN

Salient rotor (Segmental)

Radially Laminated Rotor (Flux Barrier)

Axially Laminated Rotor

ROTOR DESIGN - SALIENT ROTOR

(SEGMENTAL)

RADIALLY LAMINATED ROTOR

(FLUX BARRIER)

AXIALLY LAMINATED ROTOR

NEW ROTOR DESIGN

EXPLOSION BONDING

WORKING OF SYNCHRONOUS

RELUCTANCE MOTOR

PHASOR DIAGRAM

TORQUE EQUATION

V = E – j Isd Xsd – j Isq

I = Isd + Isq

where., V is the Supply Voltage

Is is the stator current

E is the excitation emf

Ȣ is the load angle

ɸ is the phase angle Xsd and Xsq are the synchronous reactance of direct and quadrature axis

Isd and Isq are the direct and quadrature axis current

TORQUE EQUATION

TORQUE ANGLE

CHARACTERISTICS

TORQUE – SPEED CHARACTERISTICS

ADVANTAGES & DISADVANTAGES ADVANTAGES

There is no concern with demagnetization; hence synchronous reluctance machines are inherently more reliable than PM machines.

There need not be any exciting field as torque is zero, thus eliminating electromagnetic spinning losses.

Synchronous reluctance machine rotors can be constructed entirely from high strength, low cost materials.

DISADVANTAGES

High cost than induction Motor.

Need Speed synchronization to invertor output frequency by using rotor position sensor and sensor less control.

Compared to induction motor it is slightly heavier and has low power factor.

By increasing the saliency ratio Lds/Lqs, the power factor can be improved.

APPLICATIONS

Metering pumps.

Auxiliary time mechanism.

Wrapping and folding machines.

Proportioning devices on pumps or conveyors.

Synthetic fiber manufacturing equipment.

Processing continuous sheet or film material.

APPLICATIONS

APPLICATIONS - WRAPPING AND FOLDING

MACHINES