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This article proposes a novel method to reduce rotor movement when estimating magnetic flux models for interior permanent magnet synchronous motors (IPMSMs) and synchronous reluctance motors (SynRMs). A rotation reduction technique that considers the flux saturation effect is proposed. A hysteresis controller is used to inject voltages only into the q-axis and simultaneously into the dq-axes. The rotation of the IPMSM is reduced by calculating the current at the point where the integral of the q-axis current over time becomes zero. In the case of SynRM, the rotation is reduced by calculating the injection voltage magnitudes such that the oscillation frequency of the q-axis current is higher than that of the d-axis current. The effectiveness of the proposed method was experimentally demonstrated using an 11-kW IPMSM and 1.5-kW SynRM. The proposed technique can be used for the self-commissioning of IPMSMs and SynRMs at a standstill, without rotor locking, or position sensors. [ABSTRACT FROM AUTHOR]

Due to their robustness and adaptability, position estimators based on the extended Kalman filter have been used in permanent magnet synchronous motors for decades. The time has come to extend their use to reluctance motors as well and this work focuses on the elements that hinder the transition. All passes through the availability of an accurate and analytical magnetic model, which is obtained by Artificial Intelligence tools. It is proved that the sensorless control of synchronous reluctance motors using the extended Kalman filter is possible over broad speed and torque ranges. The experimental session compares different implementation possibilities, concluding with the proposal of a new hybrid algorithm that greatly reduces the computational load. [ABSTRACT FROM AUTHOR]

The goal of this article is to develop a new topology optimization framework that can secure the manufacturability of the synchronous reluctance motors (SynRMs) with multiple iron webs and bridges while satisfying the required electromagnetic and mechanical performances. In the SynRM, multiple iron webs and bridges are crucial to achieve a higher torque and a structural safety. A minimum thickness of the web and bridge should also be guaranteed to achieve manufacturability. To acquire the optimal SynRM that can satisfy the above characteristics, a two-stage topology optimization framework is proposed with an individual filtering-and-penalization scheme. This proposed scheme can individually control the number and thickness of multiple iron webs and bridges in the rotor to obtain the manufacturable and structurally safe SynRMs. For the abovementioned purpose, topology optimization is formulated to minimize a torque ripple while satisfying the desired average torque, structural compliance, and a rotational moment of inertia. Average torque and structural compliance are evaluated by performing the electromagnetic and structural finite element analyses, respectively, at each iteration of topology optimization. Here, design-dependent loads are considered in the radial and circumferential directions to reflect a high-speed rotation. Through investigating the optimized SynRM designs with various filter radii, the relationship among the torque, structural pattern, and stress distribution is examined. Finally, the experimental results with the manufactured prototypes validate the feasibility and potential of the proposed design method. [ABSTRACT FROM AUTHOR]

A novel position estimation strategy based on lag compensation-assisted adaptive quasi-fading Kalman filter (LC-AQFKF) is proposed for synchronous reluctance motor (SynRM) sensorless drive in this article. In LC-QFKF, the quasi-fading factor is derived to avoid the harsh assumptions of conventional adaptive fading Kalman filter, and accessibility of the method is improved while ensuring the estimation accuracy. The computational efficiency of LC-AQFKF is promoted by introducing the quasi-fading factor into the prediction error covariance matrix. Moreover, the frequency characteristic of AQFKF-based active back electromotive force observer is analyzed, and the phase lag problem in high-speed situations caused by the low-pass filtering property of AQFKF is overcome. In this way, the estimation accuracy of the rotor position is significantly enhanced. Besides, the double dynamic position compensation method is put forward to strengthen the position estimation performance of sensorless SynRM drive under dynamic conditions. The effectiveness of the proposed scheme is validated at a 1.5 kW SynRM drive. [ABSTRACT FROM AUTHOR]

This article presents a structural strength analysis and noise reduction method for high-speed long primary moving-magnet-type linear synchronous motors (MMT-LSMs) applied to electromagnetic launch systems under high acceleration. The stresses and deformations of the mover and frame at different mover offset distances are analyzed and calculated to reveal that the permanent magnets (PMs) placed ectally on both sides of the mover core are easily damaged and need to be protected by sleeves. Then, the mover stresses with different sleeve materials and varied PM-sleeve interference values are compared for subsequent optimization. Furthermore, tooth harmonic is the main cause of vibration and noise when electromagnetic force waves are exerted on this MMT-LSM. Three improved methods are discussed comprehensively to reduce vibration and noise, including pole/slot combination, slot width, and pole arc coefficient. Finally, the experiment platform is built with the implementation of the modal and vibration acceleration experiments to verify the proposed analysis method. [ABSTRACT FROM AUTHOR]

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]

This article presents the control of solar photovoltaic (PV) battery-fed reluctance synchronous motor drive for light electric vehicle. The system performance is evaluated based on the Indian driving cycle (IDC). This system uses a bidirectional dc–dc converter for regulating battery power for different operating conditions as per IDC. For augmenting the performance of the battery, a rooftop solar-PV panel is installed with a dc–dc boost converter for maximum power point tracking. The reluctance synchronous motor drive is operated using three-phase voltage inverter with hysteresis current control and energy regeneration of the stored kinetic energy of the system. The speed and position of the reluctance synchronous motor drive are also estimated using flux linkages, which makes this system cost effective. The reluctance synchronous motor drive is simulated in MATLAB/Simulink for dynamic and steady-state conditions of the vehicle. The system's applicability and performance are validated by test results recorded on a laboratory-developed experimental setup in detail. [ABSTRACT FROM AUTHOR]

In this article, a method for topology optimization (TO) of a synchronous reluctance motor (SynRM) is proposed using deep reinforcement learning (RL). Due to the need for simulating a large number of finite-element models in a traditional TO task, incorporating a study involving a different problem formulation (such as a varying design domain) can be an overwhelming task. A neural network (NN)-based agent trained using an RL formulation is able to extend the knowledge from one TO design problem to other similar TO tasks. The applicability of such learning is performed using a sequence-based TO environment. It is observed that such an approach not only reduces the computation required for TO, but also introduces the capability to generalize RL to unseen TO scenarios. The proposed optimization method reduces computation time by 70%–90% when compared to a genetic algorithm-based implementation. [ABSTRACT FROM AUTHOR]

This article proposes a hybrid analytical modeling procedure for the performance parameter estimation of synchronous reluctance machine, including its operation in the region of magnetic saturation. The proposed model better estimated the torque profile through improved translation and stepped transition of rotor flux barriers. The non-linear operation is simulated by considering the global saturation and estimating the machine’s operating point on the magnetization curve of the core material. The procedure formulation focuses on improving the accuracy and rapidness of the iterative design process. The obtained results are validated against an already established design analysis technique, finite-element analysis, and the frequency spectrum analysis of practical machine results. With the improved accuracy and the least requirement of simulation runtime and computational resources, the modeling procedure can be utilized as an initial design iteration tool. [ABSTRACT FROM AUTHOR]

To meet the new international efficiency (IE) standards, line-start (LS) synchronous reluctance motors (SyRMs) are now being considered. Conventional star and delta windings are usually employed in LS SyRMs. However, combined star-delta winding has higher winding factor and lower magneto-motive force (mmf) harmonics compared to conventional star and delta windings. Hence, in this paper, LS SyRM and LS ferrite assisted SyRM with star and star-delta winding are analyzed and their performance indices are compared. A winding function analysis is used for the design of star and star-delta windings. Further, the effect of zero sequence current on the performance of the motors under comparison is presented in detail. Star and star-delta winding prototype LS SyRMs with and without ferrite magnets in the rotor are fabricated. Experimental studies are carried-out on these prototypes and the results are presented which are in close agreement with the simulation results. [ABSTRACT FROM AUTHOR]

Synchronous reluctance motors (SynRMs) with four layers of flux barriers are currently in practical use as high-efficiency motors for industrial applications. While SynRMs have higher efficiency than induction motors, they have a high torque ripple. In this study, an asymmetric rotor structure was designed to reduce the torque ripple of the four-layer SynRM, considering the mechanical strength. Two rotor structures with different flux barrier angles were combined in the stacking direction, and the ratio of the combination was optimized by finite element analysis. In addition, prototypes of the initial structure and proposed asymmetric structure were manufactured, and their torque and efficiency characteristics were measured. The experimental results show that the proposed asymmetric structure can reduce the torque ripple while maintaining the basic characteristics such as average torque and efficiency. [ABSTRACT FROM AUTHOR]

This article reviews the state-of-the-art back electromotive force (EMF) based sensorless schemes for synchronous machines. Field-oriented control (FOC) of a synchronous machine requires real-time rotor position for decoupled torque and flux control. Extraction of rotor position without a sensor or sensorless control has been an enabling technology for the past few decades. Sensorless control using back EMF voltage induced by rotor movement is the most widely used method. However, the connections and differences between different methods have not been thoroughly investigated and documented. This article first reviews basic sensorless methods. The two implementation forms of an observer are examined to facilitate analysis. A detailed analysis puts in evidence the connections behind different methods in both stationary and synchronous reference frames. A summary is drawn that is meant to offer a few key points regarding different sensorless methods. Finally, a conclusion is given to summarize the major contributions of this article. [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 presents a new type of double stator swing rotating permanent magnet spherical motor (DSSRPMSM), which can realize swing, rotation, and helical motion and is used in industrial robots, gyroscopes, satellite communications, and other fields. The proposed spherical motor consists of two stators and a hollow rotor with permanent magnet (PM) poles on its inner and outer surfaces. Compared with most spherical motor with hollow coil and traditional PM synchronous motor, the structure of the motor is different and novel, and it is difficult to find a more perfect design theory and method. Thus, this article introduces the new idea of motor design in detail. First, the structure and working principle of the motor are introduced, and the original design of the motor is carried out. The 2-D rough estimation and 3-D FEM accurate simulation calculation are carried out, and the electromagnetic characteristics of the motor are obtained, including magnetic flux density distribution, torque, and loss. The simulation results meet the design specifications of the motor. A prototype was built and tested. The experimental results are in good agreement with the 3-D FEM analysis. The design method provides a theoretical basis for the design of this kind of spherical motor. The research results lay a foundation for the subsequent optimization of the motor. [ABSTRACT FROM AUTHOR]

With high surrounding temperatures, winding resistance increases and thus lowers the operational efficiency of a motor. To meet the large application requirements and conform with the ever-increasing energy-efficiency regulations for pump equipment in the metals industry, consistent efforts have focused on producing single-phase motors that can deliver superior performance at a low cost. Because the steady-state rotational speed is synchronized and no driver circuit is required, a direct-on-line synchronous reluctance motor is a potentially viable alternative to the commonly adopted induction motors. Its inherently simple structure and comparably low operational speed necessitate a challenging structural design for accomplishing the high-efficiency objectives of pump applications. These challenges and their potential solutions are reported in detail. By employing a systematic design scheme and including thermal concerns of the performance, a competitive high-efficiency single-phase direct-on-line synchronous reluctance motor for pump applications in various metal industry equipment was offered. [ABSTRACT FROM AUTHOR]

This paper proposes a traction unit that combines an interior permanent magnet motor and a PM-assisted synchronous reluctance motor for electric vehicles to improve traction performance, enhance energy efficiency, and reduce cost. The characteristics of three traction units are analyzed and compared, including (a) rear-wheel-drive configuration using one IPM motor; (b) all-wheel-drive configuration using two interior permanent magnet motors; and (c) all-wheel-drive with a combination of one interior permanent magnet motor and one PM-assisted synchronous reluctance as proposed in this paper. The operational characteristics of each motor to achieve a wide constant power speed range are first investigated. Then, the Urban Dynamometer Driving Schedule is utilized to compare and evaluate the operational characteristics, energy consumption, and most importantly, the efficiency of the traction units. Simulation results reveal that the overall efficiency of the proposed traction unit can be improved compared to the other configurations. The advantages and drawbacks of the proposed traction unit are also investigated. Finally, experiments are conducted to validate the analysis. [ABSTRACT FROM AUTHOR]

A modified configuration for Permanent Magnet Assisted Synchronous Reluctance Motors (PMaSyRM) is studied in this paper. Conventionally, the PM materials are inserted in the flux barriers region of the rotor. Consequently, the PMs sizing parameters will be restricted to the available space that may limit the efficient use of PMs benefits. In this study, a portion of the rotor structure is replaced with an Interior PM (IPM) rotor so that an axially segmented integration of IPM and SyRM is obtained. Thus, the PMs design is performed specifically in the IPM segment independent of the SyRM scheme, while the SyRM segment remains PM-less. The main motivation of this concept is to improve the contribution of the PM material in the total torque as well as utilizing the special property of the proposed rotor configuration for pulsating torque reduction. A computationally cost-effective algorithm is proposed for the optimal design of IPM-SyRM motor by which a low-power design is carried out for a lightweight electric vehicle. The results for torque profile characteristics, PM volume, power-factor, and efficiency are compared with a conventional PMaSyRM that has been optimally designed as the reference case. Finally, a prototype is constructed to verify the theoretical analysis. [ABSTRACT FROM AUTHOR]

This article proposes a pseudo-random high-frequency triangular-wave current signal injection (PR-HFTCI) based sensorless control scheme for synchronous reluctance motor (SynRM) drives at zero-low speed domain to suppress the high-frequency (HF) loss and the HF audible noise which are introduced by the significant nonlinearities of SynRMs and the traditional constant amplitude HF square-wave voltage injection method. The pseudo-random HF triangular-wave current signal with random frequency and random phase is injected to eliminate the discrete spectrum of the current power spectra density (PSD) and the corresponding current PSD analysis is performed to evaluate it. In addition, the HF component amplitude of the d-axis voltage reference can be adjusted adaptively with the variation of load to maintain the HF current amplitude constant, it is easy to implement and does not require any extra regulator and signal processing. Hence, the HF loss and the HF torque ripple can be effectively reduced under the heavy load. Finally, the effectiveness and the correctness of the proposed PR-HFTCI based sensorless control scheme are validated with experiments on a 1.5-kW SynRM drive platform. [ABSTRACT FROM AUTHOR]

This article proposes a nonlinear controller based on feedback linearization (FL) for synchronous reluctance motor (SynRM) drives which takes into consideration the magnetic saturation. The proposed nonlinear FL control based control technique has been developed starting from the theoretical definition of an original dynamic model of the SynRM taking into consideration both the self- and the cross-saturation effects. Such a control technique permits the dynamics of both the speed and axis flux loops to be maintained constant independently from the load and the saturation of the iron core in both constant flux and variable direct axis flux operating conditions. Finally, sensitivity of the performance of the proposed FL control versus the variation of the main motor parameters has been verified. The proposed technique has been tested experimentally on a suitably developed test setup. The proposed FL control has been further compared with the classic field-oriented control (FOC) in both constant flux and variable flux working conditions. [ABSTRACT FROM AUTHOR]

This article proposes a new magnetic model self-identification technique for synchronous machines to build the flux-map look-up tables. Provided the shaft is free to turn, an alternating self-acceleration and deceleration sequence is envisaged for identification without a dedicated experimental rig or additional hardware. With respect to previous works, the stator flux and the stator resistance are adapted online during the run, thus eliminating the need for postprocessing and the sensitivity to winding temperature variations during the test. Experimental validations on a 1.1-kW synchronous reluctance and a 11-kW permanent-magnet-assisted synchronous reluctance motors are provided. [ABSTRACT FROM AUTHOR]

This article proposes a phase current reconstruction strategy for open-winding synchronous reluctance motor (OW-SynRM) drives with the dual-inverter topology and common dc bus. The traditional reconstruction strategy cannot be applied in OW motor drives because the dual-inverter modulation and zero-sequence current suppression strategies complicate the vector combinations and shorten their durations. Besides, additional sampling is required because the sum of the three-phase current is not zero. To solve these issues, the edge alignment algorithm is proposed to extend the duration of certain vector combinations, and the phase-shift strategy for the third sampling is proposed to obtain extra current information. In the case of the reconstruction failure in immeasurable regions, the corresponding compensation strategy is investigated. With the proposed reconstruction strategy, the system cost can be significantly reduced and the reliability can be improved, where only one current sensor is required. Besides, the single sensor can be reused for power detection and protection for the whole system by selective installation. Moreover, the proposed strategy is compatible with both the 180° and 120° assignment schemes, increasing the flexibility of application. Finally, experiments are carried out on an OW-SynRM to verify the high accuracy and feasibility of the proposed strategy. [ABSTRACT FROM AUTHOR]

According to International Electrotechnical Commission (IEC) 60034-1, in industrial applications not only efficiency but also power factors are important performance indexes. When comparing line motor to induction motor (IM), a line-start synchronous reluctance motor (LS-SynRM) has a high efficiency but a low power factor than that of IM. In this article, the analysis and design of LS-SynRM are carried out considering the rotor slot opening and bridges for improving the efficiency and power factor. The reference machine is selected with a 2.2 kW IM, and the performance of the reference model is analyzed based on finite element analysis (FEA). To analyze the effect of rotor slot opening and bridges, an optimal model of LS-SynRM is designed through a two-step design process. First, the design of rotor slot for synchronization is carried out, and second, the design of barriers using the response surface method (RSM) is carried out under the same conditions of the stator size of IM. Based on the basic model, the performances of LS-SynRM are analyzed according to the slot opening and bridges. Furthermore, the parametric analysis is carried out and the final model is designed considering the efficiency and power factor based on the design parameters. Finally, the final model is manufactured, and the experiment is carried out to verify the FEA result. [ABSTRACT FROM AUTHOR]

Synchronous reluctance motors show nonlinear behavior in the high torque region due to core saturation, especially on the $d$ -axis. In this study, the maximum torque per ampere (MTPA) solution is sought in the mathematical frame. First, flux linkage data are obtained from finite element method, and fitted as the plane functions of currents by the least square method. Thereafter, the inductances are derived as binomials in $i_d$ and $i_q$. These analytic expressions of inductances are used in deriving a necessary condition for the MTPA, and constructing an on-line MTPA control method. The effectiveness is verified through simulation and experimental results. [ABSTRACT FROM AUTHOR]

This article assesses the electromagnetic (EM) and thermal behaviors of a triple-redundant, 3×3-phase, permanent-magnet-assisted synchronous reluctance machine (PMASynRM) under a short circuit (SC) involving a few strands across a number of turns. Directly coupled EM-thermal simulation based on 2-D transient EM and 3-D thermal model with aid of a scripting file is adopted for analyzing thermal behavior under the most severe interstrand SC fault. The results provide a better understanding of more realistic SC behaviors in machines with stranded winding. It is shown that EM-thermal-coupled simulations are necessary to access the machine's thermal behavior under the fault conditions. [ABSTRACT FROM AUTHOR]

In order to design a high-performance synchronous reluctance motor (SynRM) drive system, a novel adaptive complementary sliding mode (ACSM) speed control and an effective d-axis current control (EDCC) are proposed in this article. First, a classical proportional-integral based field-oriented control of the SynRM drive with a constant d-axis current command is introduced. However, the constant d-axis current command is obtained by trial and error method or satisfying the minimum excitation current of the SynRM. More importantly, the constant value of the d-axis current command is not suitable for the highly nonlinear and time-varying SynRM drive at the varied load torque conditions. Therefore, an ACSM speed control with the d-axis current control (ACSMSC-DCC) system is designed for the speed regulation of the SynRM. The ACSM speed control is proposed to generate the q-axis current commands, and an EDCC by using the stator flux estimator is proposed to produce the d-axis current commands. Finally, the proposed ACSMSC-DCC system is implemented in a 32-bit floating-point digital signal processor TMS320F28075 and its effectiveness are verified by some experimental results. [ABSTRACT FROM AUTHOR]

Linear flux-switching permanent-magnet (LFSPM) motors have been proposed for electromagnetic launch system (EMLS). Benefiting from the permanent magnet (PM) settled on the long double-sided primary and the yokeless secondary, the proposed structure has the advantage of high thrust force density and simple structure compared with the traditional linear permanent-magnet synchronous motor (LPMSM) and linear induction motor (LIM), which makes it more suitable for the EMLS. However, it suffers from the deficiency of relatively high detent force due to the permanent magnets (PMs) settled on the primary, which will also exert an influence on the thrust ripple. Different from the traditional rotary motor, the linear motor also suffers from the end force caused by the end effect. So, a new structure of secondary, which is called symmetric unequally spaced (SUS) secondary in this paper, is proposed to improve the electromagnetic performance from the point of the detent force and thrust ripple for the motor. The thrust ripple and detent force are effectively declined by applying the proposed method without the sacrifice of the average thrust force. The validity of the method is verified by finite element analysis (FEA). A prototype with SUS secondary is manufactured to verify the simulation result. [ABSTRACT FROM AUTHOR]

This article presents a flux linkage-based direct model predictive current control approach that achieves favorable performance both during steady-state and transient operation. The former is achieved by computing the optimal time instants at which a new switch position is applied to the converter. To this end, the future current behavior is not computed based on the machine inductances or inductance look-up tables; instead, flux linkage maps are utilized to predict the trajectory of the magnetic flux linkage, and subsequently of the current. This is advantageous for electric drives with noticeable magnetic nonlinearity in terms of saturation and/or cross-coupling effects. Hence, by using flux linkage maps in the prediction process, the evolution of the stator current can be calculated more accurately, enabling the controller to make better switching decisions. Moreover, the discussed predictive controller exhibits excellent dynamic performance owing to its direct control nature, i.e., the control and modulation tasks are performed in one computational stage rendering a dedicated modulation stage redundant. Three different drive systems based on permanent magnet synchronous motors are examined to demonstrate the effectiveness of the presented control approach. [ABSTRACT FROM AUTHOR]

A direct-on-line synchronous reluctance motor (DOLSynRM) with a rotor topology defined by the natural flux line curve approach is studied as an alternative to an induction motor (IM) using a 1.5 kW, 50 Hz synchronous reluctance motor as an example. If an IM stator is used, a direct squirrel cage rotor replacement by a synchronous reluctance rotor equipped with a damper winding might not guarantee a sufficient starting performance. To ensure the strong enough starting capability, the natural flux line curve approach was modified in the motor design. The proposed approach was applied in the optimization of the DOLSynRM using a genetic algorithm. The optimization results show a clear tendency in the rotor design when trying to achieve a reliable starting capability and to maximize the steady-state performance of the DOLSynRM. Both the stator design and the rotor diameter of the optimized DOLSynRM are different from those of a corresponding squirrel cage IM. A DOLSynRM prototype was built and tested. It showed about a 5.4%-unit higher efficiency than the original prototype IM and acceptable starting performance under the rated load condition. The starting capabilities of the motors under study are considered with different loads. The locked rotor apparent power and current stay below permissible limits in both the IM and the DOLSynRM. [ABSTRACT FROM AUTHOR]

An 8-pole 48-slot dual three-phase synchronous reluctance motor has been tested under half control mode, that is, when only a single three-phase system is supplied while the other is not operating. Changing the terminal connections of the motor prototype available, two different winding configurations have been tested. This allows their performances to be experimentally compared. At first, the cross coupling effect between the axis in $dq$ reference is analyzed, by measuring the flux linkages for different current combinations. The torque characteristics are compared in terms of torque map, maximum torque capability and torque ripple. Then the finite element analysis has been used to explain the experimental results and to investigate the radial forces on the rotor. Finally, the impact of a lack of symmetry between the two three-phase system is investigated. [ABSTRACT FROM AUTHOR]

This article deals with the design of a synchronous reluctance (SynRel) motor for full-electric vehicle applications. In particular, the design is focused on “premium” vehicles and aims at the development of rare-earth free electric motor technologies featuring low cost manufacturing. Different solutions are proposed and compared with focus on the rotor design; the investigated topologies employ asymmetric rotor structures with “fluid shaped” barriers without radial ribs to maximize the average torque and minimize the torque ripple. As this choice is very critical for the mechanical strength of the rotor core at high speed, it has been decided to fill the flux barriers with epoxy adhesive resin. The use of the resin requires accurate mechanical analysis in order to assess the rotor robustness at high speed. The article presents the performance of optimized designs without radial ribs and it is focused on the identification of the best properties for an epoxy resin able to enhance the mechanical integrity of the rotor. Moreover, experimental tests on resin cylinder samples have been carried out in order to verify the contact pressure between the resin and a laminated core. The results of this study could be a useful guideline for the designers interested in using this technology for high speed SynRel motors. [ABSTRACT FROM AUTHOR]

In order to improve the performance (low torque ripple, low suspension ripple, and high power factor) of the permanent magnet assisted bearingless synchronous reluctance motor (PMa-BSynRM), the multiobjective optimal design based on fast nondominated sorting genetic algorithm (NSGA-Ⅱ) of PMa-BSynRM rotor topology is investigated in this article. First, the structure and operation principle of the PMa-BSynRM are introduced. Second, the initial rotor design that gives optimizer the ability to produce a variety of barrier shapes and the comprehensive sensitive analysis that evaluates the influence of each design variable on optimization objectives are presented. Third, the optimal design is selected from the Pareto front, which is generated by NSGA-Ⅱ, and validated by finite-element analysis. The simulation results confirm that the torque and suspension force capacity of optimal motor are improved significantly in comparison with initial design, whereas the value of power factor reaches 0.81. Finally, the optimal prototype motor is manufactured, and experimental results confirm the validity and superiority of the optimized design. [ABSTRACT FROM AUTHOR]

Commonly, healthy five-phase permanent magnet assisted synchronous reluctance machines (PMaSynRMs) are modeled in harmonic fixed rotating (dq1dq) reference frames. Such approaches feature several levels of detail, namely, constant parameters or saturation in four axes, i.e., 4-D saturation or cross-saturation effects in conjunction with space harmonics in 5-D models. In this article, a 6-D model is proposed that comprises all aforementioned nonlinearities not just in faultless but also in open-phase fault conditions. Moreover, magnetic axial asymmetry introduced by discrete skew is taken into account and included in the investigated modeling. The proposed 6-D model is based on flux maps obtained from static Finite-Element program posteriori modified to comprise the skewing effect. Very close to finite-element precision is guaranteed and experimental validations have been performed to confirm the authenticity and contrast the effectiveness of the open-phase model with skew. [ABSTRACT FROM AUTHOR]

The rotor flux linkage of permanent-magnet synchronous motor (PMSM) is of great importance for monitoring and high-performance control. However, most of the existing online estimation methods need prior knowledge of other PMSM parameters such as stator resistance and dq axis inductance, which are difficult to realize in the rank-deficient models of electrical machines. This article proposes a simple online estimation method of rotor flux linkage for the dual three-phase surface-mounted PMSM (SPMSM) drives with the assistance of injected position offset. The independent estimation model has been developed for the rotor flux linkage by appropriate setting of positon offset between two sets of three-phase windings of dual three-phase SPMSM drives. The proposed method not only has little influence on the output torque and high signal-to-noise ratio for observation, but also offers the superior performance in estimation accuracy irrespective of the influence of VSI nonlinearity. In addition, the proposed position-offset-based method is suitable for the full-speed region including the field-weakening operation. Finally, comprehensive experimental results are presented to verify validity of the proposed method under different working conditions. [ABSTRACT FROM AUTHOR]

In this article, a new fault-tolerant control strategy for a triple redundant 3 × 3 phase permanent magnet assisted synchronous reluctance motor under a single-phase open-circuit fault has been proposed. In order to reduce the cost of the system, a two-level three-phase inverter is constructed to drive the parallel-connected motor under normal and fault-tolerant conditions. In normal operations, the current and torque are equally distributed to the three modules of the motor, while in a fault-tolerant state, they should be redistributed according to a specific ratio. The optimal ratio is obtained by investigating the control strategy of minimum copper loss and minimum torque ripple. The torque ripple of the normal module is increased to offset the torque ripple of the fault module, thereby reducing the total electromagnetic torque ripple after the failure. It means that no auxiliary switching devices need to be added even if the failure happened, which can significantly reduce the complexity and improve the reliability of the control system. To verify the theoretical analysis, simulations and experiments have been conducted. The results are in good agreement with that of theoretical analysis. [ABSTRACT FROM AUTHOR]

In this article, a new controllable leakage flux multilayer barrier permanent magnet (PM) motor is proposed by adopting a new design concept of controllable leakage flux, where the PMs are uniquely placed in the d-axis magnetic circuit of the synchronous reluctance motor (SynRM). Compared to the conventional q-axis PM placement SynRM, the higher PM utilization and better flux-weakening capability can be obtained. For further comparison and verification, both of the controllable leakage flux multilayer barrier PM motor and the motor with traditional q-axis PM setting are designed. In addition, a multiobjective optimization method based on the correlation analysis method is proposed to obtain the optimized output torque and flux-weakening performances. Then, the performances of the two optimal motors are analyzed and compared in detail. Finally, two prototype motors are manufactured and tested. Both the theoretical and experimental analyses verify the effectiveness of the flux-weakening enhancement design and the proposed motor. [ABSTRACT FROM AUTHOR]

This article proposes a new asymmetric modular permanent magnet assisted synchronous reluctance motor (PMaSynRM) to offer low torque ripple and high reliability. First, the stator is segmented into three modules without magnetic coupling. The influence of flux gaps between modules is investigated on torque performance. For the torque improvements, the multilevel optimization strategy is conducted, which simultaneously enhances the fault-tolerant capability. Besides, the torque ripple reduction methods are proposed with the asymmetric rotor and shifted end-slots. The analytical formulae of asymmetric flux barrier angle are derived. Then, the asymmetric flux barrier is designed to reduce the 12th harmonic, and the end-slots are shifted to minimize the additional 2nd harmonic component caused by flux gaps. Finally, the enhanced fault-tolerant capability of the proposed modular PMaSynRM is also evaluated. The effectiveness of the proposed approach is verified by both simulation and experiment. [ABSTRACT FROM AUTHOR]

This paper presents a novel design concept for Synchronous Reluctance (SynRel) machines aimed at reducing the torque ripple. Two general sizing approaches based on the homothetic scaling principle are defined and compared. An in depth analysis on the torque ripple, for a wide range of scaled geometries, evaluated by finite element, has been carried out at different operating conditions. A further analysis is performed on 4 scaled geometries that have been optimized starting from 4 random rotor geometries. It is shown that the main rotor geometrical variables converge to similar values for all scaled machines. The accuracy of the proposed model is then validated by comparing the FE simulated torque ripple waveforms with the experimental data carried out, for a range of operating conditions, on a machine prototype. The outcome of this work is a fast and accurate scaling technique for the preliminary design of SynRel machines with reduced torque ripple. [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]

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]

The use of permanent magnet-assisted synchronous reluctance motor (PMA-SynRM) is increasing due to its advantages and superiority over induction motors. The undesirable effects of the encoder measurement error on the drive systems especially during low-range speeds may cause disorder in drive performance and sometimes its instability. For the low-cost application that requires a low-resolution encoder, this problem is felt obviously. This article presents a mathematical solution in order to compensate for the instability problem of a PMA-SynRM control at low speeds based on an augmented state unscented Kalman filter (ASUKF). First, a mathematical analysis for the effect of encoder error on the speed control instability is performed, and then an augmented nonlinear dynamical model for the PMA-SynRM is derived. Using an ASUKF on the presented augmented model of the PMA-SynRM, the error of the encoder is detected and accurately estimated. Using the estimated errors and pure motor state variables, the accuracy and robustness of the control are increased and its stability is guaranteed. The experiments performed for a 0.35 kW PMA-SynRM confirm the performance validity of the proposed method. [ABSTRACT FROM AUTHOR]

This article proposes a novel transient 3-D lumped-parameter (LP) thermal model and a 3-D finite-element (FE) thermal model of a triple redundant nine-phase permanent magnet-assisted synchronous reluctance machine to predict the asymmetric temperature distribution under various fault conditions. First, the predicted transient and steady-state temperatures are compared between the 3-D LP and the 3-D FE thermal models under fault conditions with uneven loss distribution. Also, the temperatures predicted by the LP and FE thermal models, which account a number of practical issues are comprehensively compared with the test results under healthy and short-circuit fault conditions. The relative merits of the two thermal models are discussed. It is shown that both models have reasonable accuracy in predicting the machine's thermal behavior under fault conditions and can be chosen according to the requirements. [ABSTRACT FROM AUTHOR]

This article proposes a novel topology optimization method using the Gabor filter, which is widely used in the field of image processing. The proposed method is applied to the optimization of a synchronous reluctance motor; its average torque is maximized, and simultaneously, the torque ripple is minimized. It is shown that the proposed method results in a motor with thin layer-shaped flux barriers, which achieves a better torque performance in comparison with a conventional model and a motor optimized using normalized Gaussian network (NGnet). [ABSTRACT FROM AUTHOR]

Electric motors used for irrigation applications contribute to a major part of worldwide energy demand. Efficiency improvement of motors used in these applications is the need of the hour. Usually, line-start (LS) induction motors are used in these applications. However, they are relatively inefficient compared to permanent magnet (PM) motors. On the other hand, PM motors have high initial cost compared to induction motors. In view of this, magnet-less machines like synchronous reluctance motors (SyRM) and PM assisted SyRM are being preferred. SyRM has poor power factor compared to induction motor and hence PM assisted SyRMs are becoming popular. In this article, a 2-pole multi-barrier LS ferrite assisted SyRM is proposed for a bore-well submersible water pump. Two-pole rotor geometry is not extensively studied for LS SyRMs. Further, the issues of ferrite magnet demagnetization for 2-pole LS applications are not explored. A separate cage is avoided by utilizing the rotor flux barriers as a cage, thereby reducing the number of ribs while housing the magnets. This improves the power factor and efficiency of proposed motor. Analytical and finite element analysis (FEA) are used for design of the proposed motor. Further, a prototype is fabricated and experimental results are presented. [ABSTRACT FROM AUTHOR]

This article proposes an alternative for robust control of synchronous reluctance motors using linear matrix inequalities to obtain fixed gains that ensure current and speed regulation, under parameter uncertainties and variations. The proposed design procedure is based on a polytopic model, which takes into account: i) uncertainties and variations of the mechanical and electrical parameters of the motor, ii) one step delay from digital implementation of the control law, and iii) internal model based controllers to guarantee reference tracking. Less conservative linear matrix inequalities, relying on slack variables, ensure robust pole location and certify the closed-loop stability for the entire domain of uncertain and time-varying motor parameters, based on parameter-dependent Lyapunov functions. The linear matrix inequalities ensure a fast and systematic computation of the control gains, that are also easy to be implemented, not adding computational complexity when compared, for instance, to usual strategies based on PI controllers. Experimental results for a 2.2 kW commercial motor are provided, validating the proposed procedure, and illustrating good tracking of currents and speed references, with suitable dynamic responses and reduced cross-coupling effects, when compared to sliding mode and PI controllers. [ABSTRACT FROM AUTHOR]

To meet the severe operating conditions in the metal industry, more thorough design and operational assessments about those implemented electric motors for specific applications must be emphasized. With its inherent robust structure, the induction motor is generally adopted to fulfill such driven objective. However, due to global warming and energy conservation concerns, those strictly enforced regulations have potentially increased the complexity and cost of high efficiency induction motor. Since the synchronous reluctance motor (SynRM) has relatively simpler structure with no copper loss in its rotor, it is a very attractive alternative for accomplishing the high-efficiency objectives of those common hoist, punch, roller, and pump applications. In addition, to eliminate drive circuits that can further reduce the overall system construction costs, the rotor barriers of the SynRM can be equipped with direct-on-line capability (DOL_SynRM) with conductors filled in. The impacts to the operational performance of these DOL_SynRMs for different applications will all be thoroughly investigated. The competitive high-efficiency DOL_SynRMs for driving various metal industry equipment can thus be offered. [ABSTRACT FROM AUTHOR]

This article compares the characteristics of a dual three-phase synchronous motor under different operating conditions such as healthy, half-control, and postfault conditions. The inductances are analyzed to confirm the interaction between two three-phase systems, and induced voltages of each phase are measured to verify the interaction behaviors. The postfault characteristics are analyzed under open-circuit faults (single-open-switch and single-open-phase faults) and short-circuit faults (single-short-switch and one-three-phase-short faults). The predicted results are validated by experimental tests. Moreover, the half-control mode is investigated as a strategy to operate with high efficiency and tolerant mode. [ABSTRACT FROM AUTHOR]

The Ironless Permanent Magnet Linear Synchronous Motor (ILPMLSM) with nonoverlapping windings is widely used in precise applications due to its simple structure, low thrust ripple, and fast response, while the disadvantage is low thrust density. The novel asymmetrical double-layer winding ILPMLSM with quasi-Halbach magnets can improve the thrust density while keeping simple structure. However, the double-layer windings are asymmetric and the primary has finite length. To solve the problem of this asymmetry and investigate its influences on electromagnetic characteristics, an improved 2-D analytical model is proposed, which introduces “virtual periodic primary” and solves the magnetic field of each winding layer. By the results of finite element and experiments, the proposed analytical model is verified. Moreover, the analytical model requires less computation time, which is helpful for optimizing design of this motor. [ABSTRACT FROM AUTHOR]

Three-phase line-start synchronous reluctance motor (LS-SynRM) is started by asynchronous torque generated by the rotor conductor bars, and runs synchronously by reluctance torque generated by the inductance difference. In this article, the rotor structure of an LS-SynRM is designed and optimized, based on the theory and characteristics of LS-SynRMs during starting and steady-state operation. First, the influence of the number of rotor flux barriers and the flux barriers ratio on the dq-axis inductance is simulated, and a better structure of rotor flux barriers is obtained. Second, according to the transient theory, a method of separating each torque during the starting process of LS-SynRMs is proposed, and the main reason for the poor starting ability of the initial LS-SynRM is analyzed. Based on the optimized structure of rotor flux barriers, the influence of the area and distribution of the rotor conductor bars on the starting ability of the LS-SynRM is studied, and the structure of rotor conductor bars under the condition of starting with heavy load (constant load) is determined. Finally, through the prototype test, the rated efficiency of the LS-SynRM is 2.8% higher than that of the SCIM is replaced by three phase squirrel cage induction motor (SCIM), which verifies the accuracy of the simulated results. At the same time, the starting current and the pull-in torque under a specific inertia are tested, and the improved effect of the synchronization ability of the improved LS-SynRM was verified. [ABSTRACT FROM AUTHOR]

This article deals with an intelligent grid integrated solar photovoltaic (PV) powered water pumping system driven by three-phase reluctance synchronous motor (RSM) drive. Here, a dc–dc converter is utilized for executing maximum power point tracking algorithm. A voltage source inverter is used for feeding the dc power to a three-phase RSM, from a solar PV array. A three-phase voltage source converter is used at the grid side for a bidirectional power transfer among the utility grid, water pump, and the PV array. This system provides rated water discharge throughout the day despite change in atmospheric conditions and feeds the surplus power to the three-phase utility grid. Moreover, during fault in any of the sources, the performance of the water pump remains unaffected. A high efficiency RSM drive without position/speed sensor is utilized here to drive the water pump. An intelligent power sharing concept, between the PV array and the grid, is used here, in which, automatic switching among all operating modes happens according to the availability of the PV array power and the grid supply. Moreover, the preference is given to the PV array power over the grid supply because of its availability at no cost. This control provides inherent power quality improvement and unity power factor operation at the grid side in all operating modes. The suitability of the system is tested through test results recorded on an experimental setup developed in the laboratory. [ABSTRACT FROM AUTHOR]

The synchronous reluctance motor is becoming a very attractive alternative to the ac induction machine. This is due to the lack of rare-earth metals in their construction and a higher efficiency, which was brought about by recent progress in rotor design. However, in order to achieve an efficient and low-cost operation of the synchronous reluctance motor drive, an adaptive sensorless algorithm should be utilized to cope with machine nonlinearities. This article describes an adaptive observer, which can provide an estimation of rotor position and speed, as well as core loss and inductance parameters. A modified pulsewidth modulation (PWM) switching scheme and a current derivative measurement method are proposed, together with an extended Kalman Filter design. Experimental results are shown to demonstrate the method performance and feasibility. [ABSTRACT FROM AUTHOR]