Investigations on the behaviour of switched reluctance generator in normal and field weakening mode of operation

Abstract

With the increasing consumption and utilization of electrical power newlineglobally, there is a steady increase in demand for power generation. About newlineone-third of all primary energy is converted into electricity of which about newlinetwo-third is used in electric motors and drives. To enhance the compactness newlineand effectiveness of the power generation and utilization switched reluctance newlinemachine can be chosen. Switched reluctance machine appears as the most newlinepromising one due to both technical and economical factors. The machine is newlinequite rugged and has many attractive features like high torque-to-inertia ratio, newlinefault tolerance and high efficiency. The low inertia of the rotor results in fast newlinedynamic response for rapid variation in the load.Like any salient pole machines, switched reluctance motor can be newlinesubjected to field weakening mode of operation to extend the rotor speeds to newlinetwo to five times beyond the rated value. Further it is interesting to extend newlinefield weakening mode of operation to switched reluctance generator also. This newlinehas been the motivation for this research work. Two experimental set-ups are newlinechosen for this purpose. First set up is chosen for low power and high speed newlinemachine to test the functioning of switched reluctance machine as a motor. newlineThe second set up is chosen for high power and low speed machine to test the newlinefunctioning of switched reluctance machine as a generator. The test machine newlineparameters are obtained through suitable finite element analysis and newlinelaboratory tests. The behavior of switched reluctance motor is analyzed in different newlineoperating regions of the Torque Speed characteristics. Region I represents a newlinestandstill condition where the torque offered by the motor is very high. As the newlinespeed increases, back-EMF increases in a linear fashion. In Region II, newlinecurrents are chopped to obtain constant torque characteristics. The non-linear newlineeffects of saturation have been addressed in Region-III when the motor newlinereaches its base speed at rated voltage and enters into angle control mode to newlinemaintain constant power.