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Torque smoothness is a strict requirement for synchronous reluctance motor (SynRM) industrial applications. The speed fluctuations induced by the high-frequency and low-frequency torque ripples deteriorate the drive performance. To suppress high-frequency torque ripples chronically omitted by conventional high-frequency signals injection methods at low-speed operation, this article proposes a bi-axes high-frequency signals injection (Bi-HFSI) scheme. A novel signal injection method is adopted, and the torque power spectrum can be broadened with discrete peaks effectively suppressed. In addition, aiming at decreasing low-frequency torque ripples, the Fourier iterative learning control algorithm that is effective in suppressing periodic disturbance is applied. It is combined with the Bi-HFSI scheme which mainly limits torque ripples at low frequencies including 1st, 2nd, and 6th harmonics. Theoretical analysis is presented, and the proposed method is verified by experiments on a 3-kW SynRM drive platform. [ABSTRACT FROM AUTHOR]

This paper presents a novel position sensorless control for 6/4 switched reluctance motors (SRMs) using only one-phase current sensor in medium and high speed. In order to eliminate phase voltage sensors, a virtual phase voltage is established to replace the real-time phase voltage in the whole conduction cycle, so as to calculate the phase flux linkage which is called virtual flux linkage. A nonlinear model is utilized to estimate the reference flux linkage-curve of any rotor position. With only one-phase current sensor, the determination of turn off angle position and phase commutation position is achieved by the comparison of reference flux linkage and virtual flux linkage. The speed estimation is performed by two reference flux linkage-current curves at particular rotor positions. Based on the obtained turn off pulse of the present phase and the turn on pulse of next phase, the remaining trigger pulse signals of three phases are derived from a delay-time strategy. The proposed scheme requires only one-phase current sensor, without any pulse injection or complicated decoupling algorithm, achieving a simple and cost-effective drive. Simulations and experiments are carried out on a 6/4-pole prototype SRM drive system to verify the correctness and effectiveness of the proposed sensorless control scheme. [ABSTRACT FROM AUTHOR]

This paper proposes a new robust field-weakening approach for reluctance synchronous motors regulated by direct torque and flux control. Compared to the existing direct torque and flux control based field-weakening methods that cannot achieve maximized DC-link voltage utilization and are parameter dependent, the proposed approach contributes to improve the field-weakening performance of reluctance synchronous motor in two aspects. First, it extends the constant power speed range through autonomous stator flux reference adjustment, which maximizes the dc-link voltage utilization. Smooth transition between the maximum torque per ampere trajectory and field-weakening trajectory is also realized. Second, it enhances the parameter robustness of drives in very high-speed region by employing a torque reference adjustment scheme. This effectively avoids the instability of drives caused by machine parameter variations. The proposed approach is verified experimentally on a laboratory setup. [ABSTRACT FROM AUTHOR]

As a kind of traction device, interior permanent-magnet synchronous machines (IPMSMs) are widely used in modern electric vehicles. This paper performs a design and comparative study of IPMSMs with different rotor topologies (spoke-type PMs, tangential-type PMs, U-shape PMs, and V-shape PMs). The research results indicate that the IPMSM with V-shape PMs is more satisfying with comprehensive consideration. Furthermore, the IPMSM with V-shape PMs is investigated in detail. The influences of geometrical parameters (magnetic bridge and angle between the two V-shape PMs under each pole, etc.) on the performances of V-shape motor are evaluated based on finite-element method (FEM). For accurate research, the effects of saturation, cross-magnetization, and the change in PM flux linkage on d- and q-axis inductances are considered. The back-electromotive force (EMF), flux leakage coefficient, average torque, torque ripple, cogging torque, power per unit volume, power factor, and flux-weakening ability are investigated, respectively. The experimental results verify the validity and accuracy of the process presented in this paper. [ABSTRACT FROM PUBLISHER]

The design of multipolar ferrite-assisted synchronous reluctance (FASR) machines is formalized via a two-step procedure. At first, one rectified machine pole is analyzed, and key figures of merit are expressed in equations to derive general guidelines for high-performance designs. Then, rotating machines are modeled as the combination of multiple rectified poles within a stack cylinder having constrained outer dimensions. It is demonstrated that, at a given output torque, the number of poles can be optimized to minimize either the Joule loss or the magnet remanence. The design approach is both finite-element analysis and experimental testing on an FASR machine, rated 795 \N\cdot \m at 168 r/min. It has been prototyped to compete with a previous solution based on rare-earth magnets, which shows similar performance. [ABSTRACT FROM PUBLISHER]

In permanent-magnet (PM) synchronous machines, when using integral-slot windings, the torque computed by using the d–q-axis theory is almost independent of the variation of the flux linkage with the rotor position. This is not verified when fractional-slot PM motors are used. The iron saturation greatly affects the torque behavior, increasing the torque ripple significantly. Particular care is necessary to determine the average torque and the torque ripple when dealing with fractional-slot PM motors. The analysis is carried out by means of a finite-element (FE) model. Since, in synchronous PM machines, the current control imposes constant d- and q-axis currents, the FE solutions are strictly related to the classical d– q-axis theory. The impact of iron saturation is taken into account, comparing a 24-slot 4-pole integral-slot machine and a 24-slot 20-pole fractional-slot-winding machine. Particular attention is given to the interior PM machines. [ABSTRACT FROM PUBLISHER]