Year

1997

Degree Name

Master of Engineering (Hons.)

Department

School of Electrical, Computer and Telecommunications Engineering

Abstract

The work presented in this thesis is aimed at the design and optimization of an interior permanent magnet (IPM) synchronous motor. Emphasis is placed on reducing the quadrature axis inductance, by means of which better vector control and faster dynamics of the machine is achieved. The reduction in q-axis inductance is obtained by shaping the airgap. A general mathematical model for both the uniform and shaped airgap machines, having a hypothetical stator winding distribution is derived in this thesis. From the mathematical model, some of the important design parameters such as q-axis inductance and torque are calculated for the IPM machine. The mathematical models are then validated using finite element analysis. The developed mathematical model is applied to two prototype machines each having different frame sizes. Calculated results from the application of the mathematical model to the prototype machines indicate that the q-axis inductance for the shaped airgap machine is reduced by about 45% when compared to the q-axis inductance of the uniform airgap machine. Calculated results from the finite element models applied to the existing prototype machine indicate that the q-axis inductance for the shaped airgap machine is reduced by about 41% when compared to the q-axis inductance of the uniform airgap machine. The percentage reduction between the shaped and uniform airgap machines, obtained from the application of finite element models to the 5.5kW prototype machine, is found to be equal to 33%. The difference in the percentage reduction between the finite element results in relation to the two prototype machines is attributed to the assumptions that are used in the winding distributions employed in the finite element models.

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