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Recently, model-based predictive current control (MB-PCC) has been presented as a good alternative to classical control algorithms in terms of simplicity and performance reliability. However, MB-PCC suffers from the high dependence on system parameters, which may deteriorate its performance under parameters variations. On the other hand, synchronous reluctance motors (SynRMs) are susceptible to suffer from inductances variations due to the magnetic saturation. Accordingly, in this article a new model-free predictive current control of SynRMs based on a recurrent neural network (RNN-PCC) is developed and proposed. The proposed RNN-PCC relies on the identification of the SynRM currents without considering any parameters. Simulation and experimental results show that both RNN-PCC and MB-PCC have similarly excellent dynamics, while better control performance and tracking errors can be achieved thanks to the proposed RNN-PCC. [ABSTRACT FROM AUTHOR]

Multiphase machines with a prime number of phases (five and seven) have shown better torque density than machines with other phase numbers. Unfortunately, these machines require a special stator design. Hence, this article proposes general rewinding techniques to obtain a five-phase winding from the existing standard three-phase stator frames. The proposed rewinding techniques are applied to construct a five-phase star-connected synchronous reluctance machine (SynRM 1) and a novel combined star-pentagon winding (SynRM 2). Simple mathematical formulations are introduced to compute the equivalent winding factor. The performance of five-phase SynRMs is analyzed using two-dimensional Ansys Maxwell transient simulations under the same copper volume for both healthy and faulty cases. SynRM 1 and 2 provide 6.56% and 13.35% higher torque compared to the three-phase SynRM at rated current and at optimal current angle. The torque ripple is decreased by 17% and 30%, respectively. Moreover, SynRM 1 and 2 offer a better performance at the faulty case; e.g., at one phase opened, the average torque of SynRM 1 and 2 is 82% and 108% higher compared to the three-phase SynRM. In addition, the torque ripple is reduced by about 63% and 81%. Finally, experimental results are done to validate the proposed winding techniques. [ABSTRACT FROM AUTHOR]

This article deals with an improved control for synchronous reluctance motor (SyRM)-based photovoltaic (PV) water pumping system, eliminating the speed controller of position sensorless field-oriented control (FOC) of SyRM. The solar water pump drive involves two stages of power conversion. The reference quadrature axis current of FOC is estimated from available PV array power that is being continuously tracked for maximum power point. This eliminates the requirement of an additional speed controller. This improves the transient behavior of overall control under dynamic conditions such as varying solar radiation. A pole is eliminated from overall characteristic equation of open-loop dc link voltage control transfer function. As a result, a single proportional integrator controller satisfactorily controls the whole pumping system. The system is much easier to tune, and by default, immune to aging and variation in pump's constant. This improves fidelity and reduces the overall cost of the system. Performance of this system is validated through a developed laboratory prototype of solar PV array-fed SyRM drive for water pumping. The overall system performance is examined under different environmental conditions. [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]

This paper explores the leakage inductance of a single-tooth wound synchronous reluctance motor and its influence on motor performance. It is shown that the stator leakage inductance heavily influences the true saliency ratio in synchronous reluctance motors and a large stator leakage inductance has a serious detrimental impact on the operating power factor. It is also shown through analytical and finite element analysis analysis that synchronous reluctance motors with single-tooth windings suffer an inherent high stator leakage inductance that is dominated the air-gap harmonic leakage component, derived from the significant stator MMF harmonics experienced with this winding type. This explains for the first time the experimental results showing a low operating power factor compared to a distributed wound machine. Measurement of the stator leakage inductance is attempted on a prototyped machine and the standardized method is found to be lacking when single-tooth windings are employed. [ABSTRACT FROM PUBLISHER]

The high-frequency signals normally used for sensorless operations in anisotropic permanent-magnet synchronous motors cause unwanted torque ripple, noise, and vibrations. The target of the present research is to extend downwards the speed range in which the sensorless drive can work without any signal injection. Specifically, this paper proposes a new back-electromotive force observer that eliminates the instability that may arise in conventional observers when the motor drive operates in generating mode. Two different versions of the observer are proposed and discussed, to include motors with high harmonic content in the back-electromotive force. The detailed mathematical analysis of the proposed observer is supported by simulations and the practical feasibility is proven through experimental results. [ABSTRACT FROM AUTHOR]

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]

The reluctance synchronous motor (RSM) is identified to be well suited for the variable-gear (VG) electric vehicle (EV) drive. It is shown in this paper, however, that the RSM drive's position-sensorless capability is limited at zero or very small current magnitudes due to a limited saliency magnitude. In this paper, a novel epoxy–resin-casted rotor with no iron ribs is proposed to increase the saliency of the RSM at zero reference current. This rotor RSM is simulated in finite-element (FE) analysis, built, evaluated, and compared with conventional flux barrier rotor RSMs. The effect of rotor skewing on the position-sensorless control (PSC) capability of the RSM is also evaluated by means of FE analysis and measurements. Other performance aspects are also considered in this paper. It is concluded that, overall, the skewed epoxy–resin-casted rotor RSM drive has no PSC problems in the entire load and speed regions and is well suited for VG EV drives. [ABSTRACT FROM PUBLISHER]