Reverse design transformer modelling technique with particular application to partial core transformers.

Abstract

This thesis first describes the conventional transformer design method used for design iron-core transformers. Limitations associated with this design method is highlighted. In this thesis, an alternative transformer design method is presented. It is called the reverse design method. This new design technique is compared against the conventional design method, and validated with experimental results. The reverse design method is applied to partial core transformers. Modifications made to accommodate full-core equivalent circuit components to partial core transformers are discussed. Particular attention is given to the derivation of core loss resistance, core magnetising reactance and winding leakage reactances. The new reverse design partial core model is applied at 50Hz normal operating temperature applications. The model is verified with experimental results. Next the reverse design model is applied to transformers when immersed in liquid nitrogen. The accuracy of the model derived previously for normal operating temperatures is investigated. Necessary modifications are made to the model. The corrected model is again justified with experimental results. Finally, the model is used for the harmonic frequency analysis of partial core transformers. Capacitive components are included as part of the analysis. Frequency responses of transformers with relatively low turn ratio are analysed, followed by high voltage partial core transformers with large turn ratio. Comparisons are made between the model calculated and test results.