Five-phase Synchronous Motor Research Articles

Пульсация потенциала общей точки трехфазной и пятифазной обмоток двигателя относительно «нуля» преобразователя

The aim of the study is to determine the parameters characterizing the ripple of a motor's three- and five-phase windings common point potentials (for the star winding connection diagram) with respect to the converter zero point. One of the reserves for decreasing electromagnetically induced vibration of an electric motor with a rotating field is to increase the number of working winding phases. The study subject is a five-phase motor winding connected to a bridge converter, namely, its ability to reduce electromagnetically induced vibration in comparison with that in using a three-phase winding. The common point potential ripple parameters are studied, and an approach is proposed to estimating the amplitude modulation of the space-time voltage vector of three- and five-phase windings under the influence of the common point potential ripple with respect to the converter zero point. Theoretical studies were carried out using the Fourier series expansion method and vector analysis methods. To confirm the theoretical results, experimental studies of the prototypes of three-phase and five-phase synchronous motors with inductors made on the basis of permanent magnets were carried out. The main results have shown the following. With increasing the number of phases of the rotating field motor working winding connected to a bridge converter, the common point potential ripple amplitude with respect to the converter zero point decreases, and the ripple frequency increases. The product of ripple amplitude by frequency remains unchanged. It is assumed that the common point potential ripple of the motor multiphase winding with respect to the converter zero terminal results in the amplitude modulation of the space-time voltage vector. With increasing the number of winding phases, the modulation amplitude decreases, and the modulation frequency increases. A five-phase motor has a lower level of the working winding common point potential ripple with respect to the converter zero point in comparison with a three-phase motor. Thus, it can be assumed that there will be a lower level of electromagnetically induced vibration in using a simple converter operation algorithm. The obtained results can be used in designing electric traction systems with vector control on the basis of multiphase motors. With increasing the number of phases, the common point potential ripple amplitude in a multiphase winding with respect to the converter zero point decreases, and the ripple frequency increases. Thus, the common point potential ripple amplitude in a five-phase winding is 5/3 times less than that in a three-phase winding, and the ripple frequency increases by 5/3 times, respectively. With increasing the number of working winding phases, the amplitude modulation of the resulting space-time voltage vector decreases. This circumstance has a positive effect on decreasing the electromagnetically induced vibration.

Synchronous-frame current control of multiphase synchronous motor under asymmetric fault condition due to open phases

In this paper, the synchronous frame current controller of a multi-phase synchronous motor with open phases is proposed. The proposed method can not only possess the superiority of a linear controller over the conventional hysteresis-type current controller but it also enables the current to be regulated without a steady state error. The key idea is that all the harmonics of the current and voltage, which can still contribute to the torque positively, can be equivalently represented as dc components even under asymmetric fault conditions. Through out this paper, a five-phase synchronous motor with one open phase is used as a practical example and the basic concepts can be easily extended into an n-phase ac motor with multiple open phases, which has the arbitrary number or configuration of the remaining healthy phases. Experimental results prove the validity of the proposed modeling and control algorithm.