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In interior permanent magnet synchronous motor (IPMSM) position‐sensorless drives, the high‐frequency (HF) square‐wave voltage injection method is often used to estimate the rotor position and speed in low‐speed range by tracking the salient polarity of the motor. In order to reduce the torque ripple caused by HF signal injection, a strategy to update the magnitude of the injected signal online by back propagation neural network is proposed in this paper. With the proposed method, the neural network can update the magnitude of the injected signal online according to the d‐axis current and the position error information. It can not only ensure the accuracy of position extraction but also effectively reduce the current harmonics caused by the injected signal, and then the torque ripple can be reduced. In addition, the proposed method is easy to implement, resulting in low computation burden. Finally, the experiments are implemented on a 1‐kW IPMSM drive. The experimental results show that compared with the conventional fixed magnitude injection, the peak‐to‐peak value of the torque ripple is reduced by nearly half along with the decrease of the injected magnitude. [ABSTRACT FROM AUTHOR]

This article proposes and investigates two asymmetric consequent-pole hybrid excited flux reversal machine (AS-CP-HEFRM) topologies, which have same numbers of iron poles and permanent magnets (PMs) with concentrated ac and dc windings on each stator pole and a salient pole rotor. If PM number on one stator pole is larger than 1, PMs are magnetized radially in the same direction on one stator pole, while opposite on adjacent stator poles. The phenomenon of the phase shift between the flux linkages of dc and PM excitations in the AS-CP-HEFRMs is revealed for the first time, which will weaken the regulation of dc excitation field to PM produced field. The elimination condition of the phase shift is derived and verified by finite-element analysis in this article, which can be considered as design guidelines in AS-CP-HEFRMs. Airgap magnetic field space harmonics of AS-CP-HEFRM are also investigated and verified by finite-element analyses. Meanwhile, the relationship between the rotor pole number and the stator pole arc (PM ratio) is derived and verified by global optimization based on genetic algorithm for maximum average torque. The influence of stator/rotor pole number combinations is also studied and compared in terms of torque, torque ripple, and flux regulation capability. The torque components produced by airgap magnetic field space harmonics are calculated and compared. A prototype has been built and tested to validate the finite element calculations. [ABSTRACT FROM AUTHOR]

The induced voltage ripple in DC field windings can cause many problems in hybrid excitation machines (HEMs). It can generate ripple current in field winding, thus causing unsteady magnetic field excitation and hence additional torque ripple and losses. Besides, the torque and power density of hybrid excitation machines may be deteriorated as a result of the influence of the induced voltage ripple on field winding's excitation circuit, particularly under high-speed conditions. Based on a hybrid excitation switched flux machine (HESFM), the influence of stator slot and rotor pole number combination on no-load and on-load field winding induced voltage ripples are studied and compared by the finite element method (FEM). It reveals that the harmonic content and thus the peak-to-peak value of the field winding induced voltage ripple are closely related to the stator slot and rotor pole number combination at both no-load and on-load operating conditions. The FEM calculations are verified by experiments on a prototype HESFM. [ABSTRACT FROM AUTHOR]