This paper presents a new strategy for the analytic determination of the natural voltage balancing dynamics of three phase flying capacitor converters. The approach substitutes Double Fourier series representations of the PWM switching signals into a non-linear transient circuit model of the three phase converter. This results in a linearised state space model with the Fourier coefficients of the modulation strategy defining the state space matrix terms. The state space model can be readily developed for converters of any level, and allows for the rapid analytical investigation of the dynamic (and static) balancing behaviour over a wide range of operating conditions. Furthermore, the approach allows powerful linear analysis strategies such as root locus methods to be used to investigate the converter performance as a function of changes in parameters such as modulation index and load. The analysis approach has been fully verified by comparison with experimental results obtained on a low voltage three phase prototype converter.
SUMMARY
The paper describes the gross heart findings in 1,557 horses. Approximately 25 per cent had cardiac lesions, of which most were valvular. There was a marked predominance of left heart involvement and the aortic valve was the valve most frequently affected. Suggested explanations for these findings are briefly discussed.
RÉSUMÉ
L'article décrit les observations cardiaques macroscopiques faites chez 1557 chevaux.
Pour 25 pour cent environ, ces coeurs montrèrent des lésions dont la plupart affectaient les valvules.
Le coeur gauche parut être le plus souvent concerné et la valvule aortique parut être le plus fréquemment atteinte.
On donne des explications à ces constatations.
ZUSAMMENFASSUNG
Die bei 1557 Pferden makroskopisch nachgewiesenen Herzveränderungen werden beschrieben. In ungefähr 25 % der Fälle konnten Läsionen gefunden werden, die zum grössten Teil die Klappen betrafen. Das linke Herz erwies sich als viel häufiger erkrankt als das rechte und unter den Klappen war die Aortenklappe häufiger verändert als die anderen. Mögliche Erklärungen für diese Resultate werden kurz besprochen.
SUMARIO
El papel describe el total de resultades encontrados en 1557 caballos. Aproxomadamente el 25 % tenía lesiones cardiacas de la cuales la mayoría era valvular. Había gran predominancia sobre el corazón izquierdo, la válvula aórtica era la válvula más frecuentemente afectada. Se citan explicaciones sobre estos descubrimientos, son brevemente expuestos.
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