Grant from Sullair Corporation


This report contains results from a finite element study of the SR machine whose dimensions were provided by Mr Lewis Unnewehr of Sullair Corporation. The objective of the study is to determine the static and steady-state operational characteristics of a given machine design to see if it meets certain design specifications. The study made use of a two-dimension, finite element program that has been developed and described in [1-3]. The same set of references also contained information on the simulation methods and types of control used in this study. Part I of this report presents the basic input data used in this study. The iron parts, including that of the shaft, are assumed to have the magnetic characteristics of M19 steel. The current distribution in the stator coils is assumed to be uniform. Part II contains the results from the FEM calculations: included in here are static characteristics of the flux distribution at several rotor positions, and computed profiles of the flux linkages, the induced emf, and the static torque as a function of rotor position for a range of current excitation. These static characteristics are for the base case design given in Table 1 and are obtained with only one stator phase energized at a time. Part III of the report contains results from sensitivity studies to determine the effects of variations in the airgap, in the relative width of the stator to rotor poles, in the shape of rotor poles, and in the skewing of the rotor poles. Unless otherwise stated the curves and data presented in this report are for the base case dimensions given in Table 1. Sensitivity analysis on airgap length, pole shape, and pole width have been obtained by making the appropriate changes on the rotor pole, the stator dimensions remained the same as those given in Table 1. Also presented are a set of static characteristics for a machine with a smaller airgap length of 0.5 mm. Finally, Part IV of report contains steady-state operational characteristics of the stator current and shaft torque of the machine operating in the current- and angle-control modes as predicted from a steady state simulation assuming a constant input dc voltage. In the steady state simulation the electrical condition of the machine and its torque output are modeled by the appropriate flux linkage, induced emf, and developed torque profiles given in Part II. At the end of the report is a brief discussion on some of the effects that we have studied, and the conclusion that the basic design, with standard angle and current controls, appears to be capable of delivering the desired torque.

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