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Zeszyły Problemowe ~ Maszyny Elektryczne Nr 86/2010

ELECTRIC DRIVE SYSTEM FED FROM PV SOLAR CELLS AHD THE POWER GRID

Abstract: Within last few years the possibility of constmcting PV Iow power gcnerators used for electric driving systems feeding emerged. The amount of energy produced by these uncomentional energy sources depends on current weather conditions. In this article the electrical drive system fed both from PV arrays and the power grid has been described. It is based on industrial freąuency comerter with special MPPT contro] algorithm. This structure is designed to meet reąuirements of most drive systems, especially 3-phase air conditioning units. Defining the minimum level of output freąuency of the freąuency com erter allows to affecl on the amount of energy consumed from the power grid. Despite the weather condition (insolation) PV array always works with maximum possibie efficiency.

Andrzej Sikora, Barbara Kulesz Politechnika Śląska, Gliwice

WPŁYW PROCESÓW KOMUTACYJNYCH NA PRACĘ TRANSFORMATORA PROSTOWNIKOWEGO O NIETYPOWYM UKŁADZIE POŁĄCZEŃ

COMMUTATION PROCESSES IN NON-STANDARD RECTIFIER TRANSFORMER

Abstract: To obtain rectified voltage needed for d.c. traction networks, different types of energy' transforma-tion circuits may be used. This paper deals with 6- and 24-puIse transformer-rectified set operation imder different supply conditions. Commutation issues have been imcstigated for Yd transformcr supplied with sinu-soidal and distorted voltage. It lias been shown that supply voltage THD factor affecting rectified voltage ąuality is not sufficient to examine voltage transformation extensively; phase angles of tlie harmonics have been researched as well and their impact on commutation processes presented. For 24-pulse system it has been shown that transformer windings connection scheme giving the desired phase shifts between secondary side yoltages is not sufficient to achieve 24 pulses in rectified voltage. Due to commutatioa this sy stem produces 6 pulsc output voltage only. In order to modemise traction substation. simple switchover from 3-phase to 12-phase transformer with presented windings connection is not. therefore. possibie.

Andrzej Sikora, Adam Zielonka Politechnika Śląska, Gliwice

PORÓWNANIE DWÓCH WARIANTÓW ZASILANIA SILNIKA BEZSZCZOTKOWEGO

COMPARISON OF TWO DIFFERENT SUPPLY VARIANTS OF A BLDC MOTOR

Abstract: Two altemative methods of supply and spced control of BLDC motor are presented in the paper. The motoe is supplied via electronic commutator. which calculated rotor position on the basis of signals re-ceived from Hall sensors. The system consists of transistor bridge connecting tlie supply voltage to the motor windings in accordance with control seąuence. The bridge is controlled by microprocessor, which works out the control basing on rotor position signals and motor input current value.