Showing papers in "Iet Electric Power Applications in 2004"

Analytical estimation of torque enhancement of the SR machine with saw-shaped (shark) pole surfaces

Abstract: The paper presents an electromagnetic analysis of the switched-reluctance (SR) machine with saw-shaped (shark) pole surfaces. This design aspect facilitates an increase of the ‘maximum/minimum’ inductance ratio, relative to the flat-pole structure, and, as such, it has drawn attention as a concept for the enhancement of the ‘torque/volume’ ratio. The analysis is based on the analytical model for estimation of the minimum and maximum inductances, which determine the extreme flux-linkage against current characteristics. These characteristics are used to predict the average phase torque at a constant current, from a given set of geometric parameters and the B–H curve describing the machine. The optimisation of the axial airgap profile is carried out by varying the tooth angle and the axial airgap pitch of the shark structure, while the other geometric parameters were kept the same as in the conventional (flat-pole) machine, which was optimised to produce the maximum torque/volume ratio. The maximum torque achievable with the shark machine is compared with the torque of the conventional SR machine at their rated currents.

Coast control for mass rapid transit railways with searching methods

Abstract: With daily commercial and social activity in cities, regulation of train service in mass rapid transit railways is necessary to maintain service and passenger flow. Dwell-time adjustment at stations is one commonly used approach to regulation of train service, but its control space is very limited. Coasting control is a viable means of meeting the specific run-time in an inter-station run. The current practice is to start coasting at a fixed distance from the departed station. Hence, it is only optimal with respect to a nominal operational condition of the train schedule, but not the current service demand. The advantage of coasting can only be fully secured when coasting points are determined in real-time. However, identifying the necessary starting point(s) for coasting under the constraints of current service conditions is no simple task as train movement is governed by a large number of factors. The feasibility and performance of classical and heuristic searching measures in locating coasting point(s) is studied with the aid of a single train simulator, according to specified inter-station run times.