SYNCHRONOUS RELUCTANCEMOTOR Syllabi Types Axial and Transverse laminated motors Operating principle Reluctance Phasor diagram Characteristics Vernier motor . Classification of AC Motors . Types of Rotor Three different types of SynRM with anisotropic rotor structures a) b) c) Simple salient pole (SP) rotor Axially laminated rotor Transversally laminated rotor . Simple salient pole (SP) rotor • The salient pole rotor as the first possibility is made by removing some iron material from each rotor in the transversal region. Four-pole conventional salient pole design . Axially laminated rotor • In the axially laminated rotor. the laminations (iron) are suitably shaped at each pole and insulated from each other using electrically and magnetically passive materials (insulation) and the resulting stacks are connected through pole holders to the central region to which the shaft is connected. which is the second type of SynRM. Four-pole axially-laminated rotor design . Thin ribs are left when punching. Four-pole transversally-laminated rotor design . thus the various rotor segments are connected to each other by these ribs.Transversally laminated rotor (Mostly Employed) • In the third type of rotor the laminations are punched in the traditional way. it becomes a permanent magnet assisted synchronous reluctance motor (PmaSynRM).Permanent magnet assisted SynRM • When PMs are inserted into the rotor flux barriers of a synchronous reluctance motor. • The polarity of magnets is chosen such that counteract the q-axis flux of the SynRM at rated load Four-pole transversally-laminated PM assisted rotor design . PMs can be mounted in the rotor core of the axially or transversally laminated structure. is a concept used in the analysis of magnetic circuits. but rather than dissipating electric energy it stores magnetic energy. . • Magnetic field causes magnetic flux to follow the path of least magnetic reluctance. or magnetic resistance. • It is analogous to resistance in an electrical circuit.Reluctance • Magnetic reluctance. projecting) electromagnet poles. such as laminated silicon steel. which has multiple projections acting as salient magnetic poles through magnetic reluctance. • Stator consists of multiple salient (ie. • The rotor consists of soft magnetic material. similar to a wound field brushed DC motor • Ferromagnetic rotor(non-permanent magnetic poles) • Torque is generated through the phenomenon of magnetic reluctance. . which minimizes torque ripple. • Number of rotor poles is less than the number of stator poles.What is synchronous reluctance motor? • A reluctance motor is a type of synchronous electric motor. the rotor torque is in the direction that will reduce reluctance. commutation gives significant control advantages for motor starting.Operating Principle When a stator pole is energized. thus constantly "pulling" the rotor along. speed control. Thus the nearest rotor pole is pulled from the unaligned position into alignment with the stator field (a position of less reluctance). In order to sustain rotation. . the stator field must rotate in advance of the rotor poles. . During run up it behaves as an induction motor but as it approaches synchronous speed. the reluctance torque takes over and the motor locks into synchronous speed.Characteristics of synchronous reluctance motor The synchronous reluctance motor is not self starting without the squirrel cage. Phasor Diagram Pm =3VIcos Pm T= ωm 3V 2 T= ωm X sd -X sq X sd *X sq . 5. 2. Synthetic fiber manufacturing equipment Wrapping and folding machine Auxiliary time mechanism Synchronized conveyors Metering pumps . 4.Applications of syrm 1. 3. hence synchronous reluctance. 2. There need be no excitation field at zero torque. 3. 4. High cost than induction motor. 2. SyRM rotor can be constructed entirely from high strength. Lower torque ripple. Disadvantages of SyRM 1. There is no concern with demagnetization. Need speed synchronization to inverter output frequency by using rotor position sensor and sensor less control. Compared to induction motor it is slightly heavier and has low power factor. .Advantage & Disadvantage of SyRM Advantages of SyRM 1. 3. low cost materials. thus eliminating electromagnetic spinning losses. • A Vernier Motor is an unexcited reluctance type Synchronous motor which has the feature of high torque at low speed .Vernier Motor • It is an unexcited reluctance type sync. • The peculiar feature of this motor is that a small displacement of the rotor produces a large displacement of the axis of maximum and minimum permeance.motor. • Thank U .