E. Pagano

Regenerative and plug braking operations of asynchronous drives for electric road vehicles

The paper presents a feeding algorithm for asynchronous motor drives which can be fruitfully used for road vehicles, because it enable the cars to run in driving and in braking operations. Plug braking operations are also possible: this means that by using of the suggested feeding algorithm, ballast resistances may be eliminated, thereby and therefore the saving usable space.

An algorithm for direct torque control of field oriented asynchronous motor drives

ContentsThe dynamic behaviour of fully digital control systems is strictly related to the duration of the sampling interval. The minimum length of this period depends exclusively on the time needed for the execution of all the required operations. Therefore, the minimization of computing time is one of the most important goals to be achieved in order to improve the accuracy of electrical drives with fully digitalized control systems. The best results can be obtained using fast programming languages and short sets of computing instructions. This goal is achieved using a proper feeding algorithm for asynchronous motor drives called “direct”, because it links directly the requested torque and magnetic flux to the input voltages.ÜbersichtDie Dynamik einer vollständig digitalen Regelung ist eng verbunden mit der Dauer des Abtast-Intervalles. Die Mindestdeuer der Periode hängt ausschließlich von der erforderlichen Rechenzeit ab. Deswegen ist die Minimierung der Rechenzeit eines der wichtigsten Ziele für die Genauigkeit elektrischer Antriebe mit vollständig digitaler Regelung. Die besten Ergebnisse können mit schnellen Programmiersprachen und kurzen Befehlssätzen erlangt werden. Das Ziel wird erreicht durch einen geeigneten Algorithmus für Asynchronmotoren. Dieser Algorithmus wird “direkt” genannt, weil er das elektromagnetische Moment und den magnetischen Fluss direkt mit den Eingangsspannungen verbindet.

Mathematisches Modell umrichtergespeister Gleich- und Wechselstrommotoren mit besonderem Augenmerk auf die Stromverdrängungsphänomene in den Ständer- und Läufernutenleitern

ÜbersichtIn der vorliegenden Arbeit wird ein mathematisches Modell vorgestellt, welches es gestattet, Stromverdrängungseffekte in Gleichstrommaschinen und Asynchronmaschinen zu berücksichtigen. Der Vorteil des mathematischen Verfahrens besteht in der Beschreibung des Skineffektes bei eingeprägten Spannungen und nicht bei eingeprägten Strömen, wie sonst in der technischen Literatur üblich. Das Modell führt auf Integral-Differentialgleichungen vom Faltungstyp. Es wird eine Lösung angegeben, und die numerischen Ergebnisse zeigen den Einfluß der Wirbelströme in umrichtergespeisten Gleichstrom- und Asynchronmaschinen.ContentsThe paper proposes a mathematical model which enables us to take into account the skin effect in de and ac machines. The advance of the mathematical procedure consists in describing the skin effect for impressed voltages and not for impressed current, as generally made in the technical literature. The model gives rise to integral-differential equations of delay-type. A solution is shown and numerical results are given to evidence eddy current influence in de and ac inverter-fed machines.

INSTABILITY REGIONS OF VARIABLE FREQUENCY SUPPLIED ASYNCHRONOUS MOTORS

The paper tries to answer the question if and when unstable opera-voltages. It is found and shown that unstable operating ranges are in practi-ce greatly reduced in comparison with theoretical evaluations, obtained by sim parameters. The reduction is effectively due to the restriction of these ran-ges, which is connected to the physical relations among motor parameters whichare taken into account by the designing techniques. It is also found that asgreater is the output constant as smaller is the possibility to obtain red unstable operations. Illustrative tables are shown to summarize the results obtained and to give a quantitative answer to the first mentioned questions.

Instability Regions of Variable Frequency Supplied Asynchronous Motors

Abstract The paper tries to answer the question if and when unstable operations occur in practice in asynchronous motors supplied by variable frequency voltages. It is found and shown that unstable operating ranges are in practice greatly reduced in comparison with theoretical evaluations, obtained by simply considering the independent variation of motor electrical and geometrical parameters. The reduction is effectively due to the restriction of these ranges, which is connected to the physical relations among motor parameters which are taken into account by the designing techniques. It is also found that as greater is the output constant as smaller is the possibility to obtain red unstable operations. Illustrative tables are shown to summarize the results obtained and to give a quantitative answer to the first mentioned questions.