A study of phase advance networks for A.C. control system stabilisation

Abstract

The M.;.bs oarriet dOnrd± system is discussed and varioUs methods Of applying stabilisation are considered. The brldged-T neIWOrk Is designed to produce the characteristic notch response and the resulting modulating frequency characterlston is discussed; The filter is considered from a pole-zero aporoach and the limitations and effects caused by temnerature, component tolerances and carrier frequency drift are considered in detail.
In chapter 3 an active filter that will produce a symmetrical response is discussed and this provides an improved phase advance chtracteristic when compared to that of the asymmetrical notch response of the bridged-T filter. It is also shown that the modulating frequency characteristics of a network which has a linear phase and constant-amplitude characteristic will be virtually unaffected by temperature, component tolerances and significant changes- in carrier frequency; a cascaded filter is designed to produce this type of response.
The cascaded filter is designed by considering the locations of the poles, and zeros, and a dominant zero analysis technique is developed to obtain an optimum filter response. Chapter 4 considers in detail the experimental results for this filter.
In chapter 5 the response of the cascaded and bridged-P networks to frequency changes is analysed and the theoretical and experimental results compared. These networks are then senarately included in a com -olete a.c. servo system and the response of the system analysed. The thesis concludes with a general discussion of the project and analyses the significance of the results.