John Rosa

Utilization and Rating of Machine Commutated Inverter-Synchronous Motor Drives

For a dc-link type variable frequency inverter-synchronous motor drive, the relationship between the operation of the machine commutated thyristor inverter and the characteristics of the synchronous motor are analyzed. The factors of maximum motor utilization, the required rating of the machine-side converter (inverter), and the rating and input power factor of the line-side converter (rectifier) are established. The effect of four different firing angle control principles applied to the machine converter on rating and performance is analyzed.

Calculation of flux linkages in multiwinding transformers

Numerous power electronic applications necessitate the use of multiwinding transformers. Transformers having n windings per phase have (n−1)2 leakage inductances. Of these, n−1 are self inductances, the rest are mutuals. This paper presents an equivalent circuit for the multiwinding transformer and outlines a method of calculating the leakage inductances for a given transformer of specified winding structure and dimensions. Examples are presented illustrating the effect of winding arrangements on the leakage inductances.