• DEVRAJ ROY

      Articles written in Sadhana

    • A novel and precise on-line digital measurement of unsaturated phase inductance of a switched reluctance motor

      DEVRAJ ROY MAINAK SENGUPTA

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      This paper presents a simple and accurate method for the on-line measurement of the unsaturated phase inductance of a switched reluctance motor (SRM). The basic principle behind the approach is to obtain the instantaneous flux linkage of the phase, which when divided by the instantaneous current of the correspondingphase will dynamically generate the phase inductance for that rotor position. A numerical division process, based on Newton–Raphson (N–R) iterative method, has been implemented using the sensed current and estimated flux linkage on an FPGA platform to generate the inductance value at each instant. It is ensured in the practical implementation that the iron parts do not saturate. It has been also verified through simulation using standard finite-element method (FEM) software packages. Further, it has been established that the effect of mutual inductance is negligibly small. The proposed method will give the true value of the unsaturatedinductance of the phase identified for diagnosis/measurement. Practical results, for the experiments conducted on an existing 4 kW, 1500 rpm Oulton-make SRM, have been also presented. They are further validated against the results obtained from FEM analysis and against previously published results of the phase inductance values for this SRM. The results are found to be in very good agreement.

    • Investigations on current waveform unbalance in a conventional switched reluctance motor even under healthy operating conditions at steady state

      DEVRAJ ROY MAINAK SENGUPTA

      More Details Abstract Fulltext PDF

      This paper presents a detailed analysis of current unbalance in a conventional switched reluctance motor (SRM) even under healthy operating condition at steady state. It is pinpointed that the phenomenon is quite expected and originates from inherent unbalance in the flux path variables. The phase currents of the motor are found asymmetric with different peak values during the normal operation, which is apparently paradoxical. Interestingly, it is also noted that the difference between the peak phase current values is varying with the load.FEM based analysis has been performed with two different terminal connection of the phase windings to the power electronic converter. The simulation results have established the effect of terminal connections of the phase winding to the power electronic converter in motor current profile. These effects are duly explained using magnetic circuit concepts and thereafter justified through detailed analytical derivations. mmf drop calculations convincingly established that the phase current unbalance arises from inherent flux path asymmetries during phase switching. The results from mathematical analysis and simulations are corroborated by accurate experimental results.

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