VOLTAGE RATIO IN SYNCHRONOUS CONVERTERS 233 



In order to change the relative voltage ratio from i to .9 by third 

 harmonic control, involves a 10 per cent third harmonic in the 

 diametral tap E.M.F., which corresponds to about 30 per cent third 

 harmonic in flux distribution curve. To make the same change by 

 seventeenth harmonic control, involves a 12 per cent seventeenth 







-.1 



1.3 



1.2 



1.1 



. 

 Km 



i ? f * 



Qm^ffo Harmonic in 



180 



FIG. 32. 



harmonic in diametral tap E.M.F., and a seventeenth harmonic in 



I 2 



the flux distribution curve of 7 per cent. For twenty slots per 



r!7 



pole, this would mean a 150 per cent seventeenth flux harmonic. A 

 combination of harmonics produces about the same result as a single 

 one of the same total per cent magnitude. 



