Table of Contents
What is the reluctance torque?
Reluctance torque is the torque generated because the motor is moving to a position where the reluctance seen by the armature flux is declining. A simple application of this principle is the refrigerator magnet, which is held in place by reluctance force.
Why self reluctance torque is zero in rotating cylindrical machines how torque is produced in these machines?
This torque is created additional to the torque produced by the locking of excited poles with synchronously rotating magnetic field. This effect is absent in cylindrical rotor machine as the air gap is uniform.
Which components are responsible for generation of reluctance torque in salient pole machine?
The torque so developed by the interaction of stator and rotor magnetic field is the electromagnetic or interaction torque. Electromagnetic torque or interaction torque depends on the direction of current in stator and rotor windings.
What is reluctance in a motor?
A reluctance motor is a type of electric motor that induces non-permanent magnetic poles on the ferromagnetic rotor. The rotor does not have any windings. It generates torque through magnetic reluctance. Reluctance motor subtypes include synchronous, variable, switched and variable stepping.
What is reluctance torque draw the torque speed characteristics of a reluctance motor?
The torque speed characteristic of synchronous reluctance motor is shown in fig. The motor starts at anywhere from 300 to 400 percent of its full load torque (depending on the rotor position of the unsymmetrical rotor with respect to the field winding) as a two phase motor.
How reluctance torque is advantageous for EV motors?
Advantages and disadvantages A switched reluctance motor offers many benefits against other types of electric motors because of its control flexibility, simple structure, lower cost and high efficiency. Furthermore, it results in a rugged and simple structure and low manufacturing cost.
How is reluctance torque produced?
Reluctance torque or alignment torque is experienced by a ferromagnetic object placed in an external magnetic field, which causes the object to line up with the external magnetic field. An external magnetic field induces an internal magnetic field in the object and because of this torque is produced.
How does a reluctance switched motor work?
The working principle of the switched reluctance motor is, it works on the principle of variable reluctance that means, the rotor of this motor constantly tries to align through the lowest reluctance lane. The formation of the rotary magnetic field can be done using the circuit of power electronics switching.
Why the reluctance motor has low efficiency?
This is due to variable reluctance throughout a rotor revolution. There is no practical application for a large synchronous reluctance motor. Low power factor, low pull-out torque, and low efficiency are characteristics of the direct power line driven variable reluctance motor.
Why is the three phase reluctance motor preferred over single phase reluctance motor?
Why is the three phase reluctance motor preferred over single phase reluctance motor? Explanation: The reluctance motor is a small synchronous motor with salient pole rotor. Explanation: The power factor in the reluctance motor is lagging power factor. The efficiency of the machine is about 55-75\%.
What is the difference between reluctance motor and induction motor?
The motors start as induction motors. When they approach synchronous speed, the slots enable the synchronous magnetic field to lock onto the rotor. The motor then turns at synchronous speed so long as the required torque is low. In the reluctance motor, the rotor has projecting poles that resemble individual teeth.
How is reluctance torque developed?
How to calculate reluctance motor?
Reluctance Motor depends on the reluctance torque for its operation. it is calculated by the formula Where, T rel – average value of reluctant torque. Reluctance torque is mainly developed in the reluctance motor.
It shall also be noted from the reluctance torque term that Reluctance Torque, is independent of direction of current in stator and rotor windings. Last term i.e. IsIr(dMsr/dƟr) represents that component of total torque which depend on both rotor and stator current and also on the angular rate of change of mutual inductance Msr.
What is the difference between cylindrical and salient pole synchronous motors?
Because of this reluctance torque, a synchronous motor with the salient pole rotor can produce more torque than a synchronous motor with the cylindrical rotor. In addition, this motor has the output torque to drive a load even if the field current is zero.
What is the reluctance torque of a brushless motor based on magnets?
Here, the flux from the field sees about the same reluctance as the flux from the winding, because the permeability of magnet material for most modern brushless motors is so close to that of air. As a result, motors based on surface-mounted magnets do not produce substantial reluctance torque. Figure 15.27.