No abstract

This paper presents the modeling, simulation and control aspects of four-quadrant switched reluctance motor (SRM) drives. The design of SRM drive systems must be focused on application based appropriate control and engineering solutions needed to overcome the practical issues. A complex model, incorporating the important dynamics of the SRM, is described for the physical motor simulation. A simpler, but quite accurate, model is presented for the SRM controller. Various practical limitations have been incorporated in the simulation model to make it closer to the experimental set-up. The SRM control parameters are chosen based on torque-per-ampere maximization requirement. Experimental results for a 1.0 kW switched reluctance motor obtained on a digital platform are presented along with useful guidelines for prototype implementation.

Efficient use of fertilizer is needed to meet the increasing food demand, minimize negative environmental impacts, and maximize farmers’ profits. Fertilizer deep placement (FDP) could be one of the best management techniques to achieve these multiple benefits. Experiments were conducted in 115 farmers’ fields spread over 35 upazilas across eight districts over nine contiguous rice (Oryza sativa L.) growing seasons during 2009 to 2012 in southern Bangladesh to compare the effects of deep placement of urea briquettes (UB) and nitrogen–phosphorus–potassium briquettes (NPK), with farmers’ broadcast prilled urea (PU) on rice yield and net economic return. Deep placement of either UB or NPK significantly increased grain yields and net economic return across all the rice‐growing seasons and years compared to PU. Across the years, average yield increase in UB and NPK over PU was higher during the Aus and Aman (wet) seasons (21–31%) than in the Boro (dry) season (11–17%). In addition to increase in grain yield, deep placement of UB and NPK saved urea by 33 and 44%, respectively, during the Aus–Aman seasons, and by 35 and 28% during the Boro season. The deep placement of one 2.4 g NPK (∼44 kg N ha−1) for the Aus–Aman season and two NPK (87 kg N ha−1) for the Boro season would be more profitable for southern Bangladesh. The FDP also provides the greatest benefits under rainfed wet season conditions where farmers have little control of water management and timing of N application.

No abstract

A geometry based simplified analytical model that decouples the current and position effect on flux and torque in the switched reluctance motor (SRM) drives is presented in this paper. This model gives a direct relation between phase current and torque accounting for the high degree of nonlinearity of the machine. A simple flux model and its inverse relationship have been developed to meet the diverse requirements of controller design. The paper emphasizes and demonstrates the importance of these relationships for real time controller implementation of high performance SRM drives.