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The low-cost magnet less switched reluctance motor (SRM) speed-torque characteristics are perfectly suited for electric vehicles (EVs) drive performances are better than polyphase machines. The main drawback of SRM for EVs is torque ripple, it can be mitigated by optimal design aspects. In this study, to design SRM by changing the position of the stator and rotor pole, an increasing number of poles are investigated with optimum geometry. This paper presents the design procedure for EV applications of 250 kg mass, developed power of 2.9 kW and acceleration of 30 kmph. SRM rotor modification with two different cases of design of SRM with exterior rotor case with three-phase stator configuration 8/6, 10/6 and design of SRM with an interior rotor with three and four phases stator configuration 6/4, 8/6. The simulation was carried out using an electromagnet infolytica simulation package. The conditions of flux linkages, static torque, and rotor configurations are obtained using finite elements. FEA is used to verify the design of the SRM from an electrical standpoint. The results and performance analysis of the SRM drive were compared and analyzed for both cases. It is observed during the static and transient analysis that, the torque ripple in the 8/6 interior rotor design is lesser than in the exterior rotor design. The Interior rotor configuration 8/6 model may best be suited for EV’s high-speed application due to its low torque ripple characteristics compared to other models.

Summary: The switched reluctance motor (SRM) is a prominent electrical machine drive with low cost and good performance in different drive applications. This machine's main drawbacks are torque ripple and flux ripple. However, the existing SRM‐operated direct torque control (DTC) Voltage vectors (VVs) give high torque ripples due to improper sector division and minimum selection of VVs switching states. On the other hand, a two‐level hysteresis torque band can result in torque ripples. Therefore, this paper proposed DTC using 16 partitions, active small and large VVs, and a multilevel hysteresis torque band (MHTB) strategy to mitigate the torque ripple further. More active VVs (i.e., 16) are employed in the modified sector‐based switching tables, suppressing the torque ripples. The proposed strategy is verified and validated using MATLAB/Simulink. The detailed result discusses the response of torque, flux, and speed of SRM. The DTC‐operated SRM drive experimental results prove the effective minimization of torque ripples in the proposed DTC compared to the existing DTC. [ABSTRACT FROM AUTHOR]

Robust data on the spatial distribution of land degradation is important for resource conservation planning. Spatial land degradation status of India was mapped using multi-temporal Linear Imaging Self Scanning Sensor (LISS-III) data acquired from Resourcesat-1/2 during 2005-2006 and 2015-2016 under the Natural Resources Census programme of the Indian Space Research Organisation. Heads-up on-screen visual interpretation of multi-season satellite data was carried out, supported by digital elevation model and other historical maps available. Visual interpretation cues were developed and employed across various partner institutions to achieve consistency in mapping. The outputs were subjected to two-stage quality check. Results indicate that the total land degradation of India was 91.2 M ha (27.77% of the geographical extent of the country) during 2015-2016 against 91.3 M ha during 2005-2006. During the ten-year period, there was an overall decrease of around 0.1 M ha in degraded land. However, noticeable intra- and inter-class changes were observed in land degradation during the ten-year period. Major reclamation was noticed in sand dunes which were converted into crop lands by levelling them. Substantial decrease in severity and extent of salt-affected soils was noticed in Uttar Pradesh. [ABSTRACT FROM AUTHOR]