Влияние временной последовательности чередования фаз семифазной обмотки на формирование результирующего вектора напряжения

Abstract

The subject of the study is a seven-phase symmetric winding, namely, its properties due to the possibility to alter the phase timing sequence. The seven-phase ABCDEFG winding can be connected to a symmetrical seven-phase voltage with different phase timing sequences: ABCDEFG, ACEGBDF, or ADGCFBE. In the study, the vector analysis methods, methods of expanding in a Fourier series, and grapho-analytical function analysis methods were used. The results of theoretical studies are confirmed by experimental data obtained on a prototype seven-phase engine sample. It has been found that with the phase timing sequence ACEGBDF of the seven-phase winding ABCDEFG, the operating space-time vector is the vector of the fifth harmonic component, which rotates in the opposite direction in comparison with the space-time vector that is produced with the phase timing sequence ABCDEFG. With this phase timing sequence, it is only the fifth phase voltage time harmonic component that produces the space-time vector. With the time sequence ADGCFBE, it is only the third time harmonic component that produces the resulting space-time voltage vector. By changing, using the converter control algorithm, the phase sequence, it is possible to obtain three values of the field rotation frequency with the same converter frequency value. These properties broaden the seven-phase machine control capabilities, a circumstance that can be used in implementing modern electric traction drives.