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This article proposes a magnetic flux saturation model that well represents the cross saturation of synchronous reluctance machines (SynRMs) and a parameter estimation method of the proposed saturation model. Existing magnetic flux models do not satisfy the reciprocity condition or express cross saturation well. The proposed flux saturation model consists of terms for self-saturation and cross saturation, and it expresses well the nonlinear relationship between current and flux of SynRMs, as well as satisfies the reciprocity condition. The data of flux saturation are obtained at standstill using the hysteresis voltage injection method. Using the flux saturation data, the parameters of the flux saturation model are estimated. Because the proposed magnetic flux saturation model includes an arctangent function, it is not possible to estimate parameters directly using the linear least-squares method (LSM). However, the proposed parameter estimation method integrates the self-saturation model and transforms it into a polynomial to which linear LSM can be applied. In addition, parameters related to cross saturation are also estimated using linear LSM. Therefore, the proposed parameter estimation method is easy to implement and can be applied to general-purposed inverter products. The effectiveness of the proposed model and its identification method are experimentally evaluated with a 1.5-kW SynRM. Additionally, the identified model is verified with the accuracy of the maximum torque per ampere table and the performance of sensorless control of the tested motor. [ABSTRACT FROM AUTHOR]

Most of the existing diagnosis techniques for interturn short circuits (ITSCs) in switched reluctance motors (SRMs) suffer from three major issues. 1) The problem of lower sensitivity where the system cannot detect an ITSC if a lower number of turns are short-circuited; 2) Interference of load variation on the detection reliability in which the fault index might initiate false alarm without any fault; 3) The dependency of the diagnosis system on the control strategy on which the motor is operating. This article proposes a novel method to diagnose ITSCs in SRMs independent of control schemes with better sensitivity and reliability using the signal injection technique. In SRMs, not all the phases take part in the torque production at any instant. The idle or inactive phase is injected with a high-frequency (HF) voltage signal for a preselected injection ratio within an electrical cycle. Any change in the winding parameters owing to an ITSC fault is deciphered by monitoring the HF currents generated in the phase windings. The results are validated experimentally for a four-phase 8/6 SRM employing two control strategies: 1) chopped current control and 2) angle position control. [ABSTRACT FROM AUTHOR]

In this article, a wireless resolver is proposed and implemented for wireless switched reluctance (SR) motors, which can detect the rotor position and transfer the information to the primary side without involving any battery storage or active components at the secondary side. The key is to integrate wireless power transfer (WPT) into a variable reluctance resolver to detect and transmit the rotor position. Compared with previous wireless SR motors adopting the Hall effect position encoder and Bluetooth communication, the robustness is highly improved, and the communication delay caused by the connection interval can be solved. Therefore, the proposed system takes the definite advantages of better dynamic performance and sealability. Besides, there is no need to specially design the SR motor, as all existing SR motors and other similar kinds of motors can readily employ this wireless resolver. An experimental prototype has been built for verification, which works well from 100 to 900 rpm with 20 mm WPT distance, and the additional power for position detection can be limited to 1.05 W while the motor consumes 54 W. [ABSTRACT FROM AUTHOR]

In this article, a simplified pulsewidth modulation (PWM) strategy is proposed for open-winding flux modulated doubly-salient reluctance motor (FMDRM) drives for switching action minimization and common-mode voltage (CMV) reduction. Conventionally, the open-winding converter topology is utilized to achieve the zero-sequence current flow path and dc-biased sinusoidal current excitation for the FMDRM, where the switching actions of power switches are doubled compared to the conventional modular three-phase converter, leading to higher switching losses. Different from the conventional space vector PWM scheme, the reference voltages of converter legs are directly calculated by the reference phase voltages in the proposed PWM scheme. In addition, a rotor-position-based sector division method is proposed to deal with the sector imbalance caused by the distorted back electromotive force (back EMF). Furthermore, different leg voltage clamping methods are respectively developed in odd and even sectors for switching action minimization, which can achieve voltage stress balance and CMV reduction. With the proposed scheme, the switching actions in each switching cycle can be reduced by half, which effectively increases the system efficiency of the FMDRM drive. Experiments are carried out on a three-phase 12/8 FMDRM prototype to verify the effectiveness of the proposed scheme. [ABSTRACT FROM AUTHOR]

In this article, a leaf spring insertion to the stator back iron is proposed to reduce vibration and acoustic noise in a switched reluctance machine (SRM). The back iron of the tooth tip is curved out and the material made up of carbon spring steel is placed to dampen the vibration due to radial force. A 6/4 stator/rotor pole SRM is designed and its natural vibration mode frequencies are determined through finite-element analyses. The optimal current waveform is applied to the SRM model using the multidisciplinary coupled simulation method to determine the radial force with the harmonic orders. In the final step, the proposed leaf spring architecture is optimized to achieve the most dampening for the effective radial force harmonic orders. The simulation and experimental results confirmed the effectiveness of the leaf spring insertion in reducing the noise and vibration in SRMs. [ABSTRACT FROM AUTHOR]

This article proposes a simple method to calculate a current vector trajectory for the enhanced operation of the electric power generation system based on a synchronous reluctance machine (SynRM). Owing to magnetic saturation and cross magnetization, the performance and the torque capability of a SynRM vary according to the position and the value of the stator current. State-of-the-art control methods usually assume parameters with constant values, especially the inductance, neglecting saturation, leading to possible uncertainty in the machine operation. Therefore, a current vector trajectory to operate this type of machine, as a generator, in an extended speed range, with enhanced performance and considering magnetic saturation is proposed. A straightforward algorithm based on the inductance characteristic of the machine is used to calculate the trajectory of the stator current vector. This trajectory is evaluated via the numerical simulation of an experimentally validated finite-element model of a SynRM. The results show that the proposed current vector trajectory can improve the torque capability to 5% concerning the estimated trajectory without considering saturation. Experimental results are also provided to demonstrate the enhanced operation of the generator. [ABSTRACT FROM AUTHOR]

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]

In this article, a novel multiple three-phase PM assisted synchronous reluctance machine with delta windings is proposed for enhanced fault tolerance. The delta connected windings offer an additional degree of freedom of the phase currents. Hence, this machine drive could provide higher torque under phase open-circuit condition. More importantly, the delta windings inherently contain zero sequence current path and could help reducing the turn fault current in the event of the most challenging turn short-circuit fault. Owing to the zero sequence current, the residual flux linkage of the fault turn is more effectively nullified leading to lower fault current. The proposed machine performance together with fault tolerant capability under various fault scenarios are investigated and compared with the star connected winding machine by detailed finite element simulation and experimental tests. It shows that the two machines have the same performance under healthy condition whilst the delta winding machine exhibits higher fault tolerance. These advantages are achieved simply by changing the winding connections without any extra cost. Thus, it is more favorable for the fault tolerant applications. [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]

This article proposes a rotor attitude estimation (RAE) method for spherical motors using the multiobject Kalman kernel correlation filter (MKKCF) algorithm in monocular vision. A permanent magnet spherical motor (PMSpM) is adopted as the research object, and a monocular area scan camera is equipped in the RAE system with a visual feature component mounted on top of the rotor output shaft. In the proposed MKKCF algorithm, the Kalman filter is used to enhance the robustness and accuracy of KCF tracker for each object. To simplify the proposed algorithm verification, a one-object tracking comparison is conducted among the KCF algorithm, the fast discriminative scale space tracking (FDSST) algorithm, and the Kalman KCF algorithm, and the results show that Kalman KCF tracker is more applicable for RAE. In addition, an RAE test bench is developed, and the MKKCF-based RAE method and the micro-electro-mechanical system (MEMS) (MPU9250) method are compared when estimating the rotor attitude. To set a benchmark, the contact rotor position measurement with encoders is used. The comparison results indicate that the MKKCF-based RAE method works with higher accuracy than the MEMS method. Finally, a closed-loop PMSpM control experiment is conducted by using the proposed MKKCF-based RAE method, and the practicability of the proposed method is proved. [ABSTRACT FROM AUTHOR]

This article proposes an online diagnosis scheme for transistor faults of asymmetric half-bridge converter (AHBC) in switched reluctance motor (SRM) drives. In order to extract more information from the phase current to identify faults, based on the conventional current measurement method, two novel current measurement methods are presented by reconstructing current sensors. According to the novel current measurement methods, a current prediction method is raised. The phase current at the kth sampling time is available so that the estimated current can be calculated. The fault can be detected and located by analyzing the given and actual switching states, which are deduced by comparing the measured and estimated currents. Compared with existing methods, the proposed scheme can be applied to diagnosis of multiple faults in n-phase AHBC, which can operate at various control strategies and chopping modes. With a single current sensor in each phase, the scheme will not increase the cost and complexity of the SRM drive. Furthermore, the scheme does not require complicated computation, making it easy to implement online. The experimental results confirm the effectiveness and flexibility of the proposed scheme. [ABSTRACT FROM AUTHOR]

In this article, we deal with design considerations of a new ac hybrid-excitation permanent-magnet machine with axial stator. Due to the presence of an axial stator, the machine features a typical three-dimensional geometric structure and field distribution. A simplified reluctance-based network is developed to capture the main design features of the machine. The analytical equations are deduced relating the main geometric dimensions to the machine design criteria: speed, power, and flux regulation capability. The influence of key machine geometric parameters, i.e., radial/axial air-gap length, stack length, and bore diameter, on output power, flux density, and flux regulation capability is investigated. It is found that there is a design tradeoff between the machine power density and flux regulation capability. The d/q-axis inductance and its ratio, which has an influence on flux weakening capability and operation performance, is examined. Finally, a 6-pole/36-slot prototype is built. Intensive experimental tests are carried out to verify the machine characteristics. [ABSTRACT FROM AUTHOR]

Thanks to the absence of rotor windings and permanent magnets, switched reluctance motors have a small weight construction. The integration of a modular power converter in a switched reluctance motor leads to a highly compact and fault-tolerant motor drive with small weight and high power density. In this article, a polygon-retrofitted integration topology is proposed for switched reluctance motors. Both the switched reluctance motor and the power converter are cooled with one shared cooling circuit. The power converter is designed and implemented using silicon carbide technology for its low losses and small thermal resistance. The proposed integration topology is extensively studied using multiphysics modeling and experimental measurements on a fully integrated rotating setup. A highly compact and power dense drive of 3.1 kW/L is obtained. [ABSTRACT FROM AUTHOR]

In this article, a low-ripple continuous control set (CCS) model predictive torque control (MPTC) method for switched reluctance machines (SRMs) is proposed. The inherent high nonlinearity of the SRMs makes it difficult to solve the optimization problem in the CCS MPTC algorithm analytically. To address this issue, an equivalent linear SRM model is adopted, and the cost function is also properly modified. Then, with the torque boundary values provided by executing the voltage vectors of an improved switching table, the optimization problem in the CCS MPTC method becomes simple and analytically solvable. The Lagrange multiplier method is employed to solve this optimization problem analytically and generate the optimum torque reference values for the active phases. Based on the estimated torque variation rates, the duty cycles for each phase are calculated. Extensive simulation and experimental tests are carried out in a four-phase 8/6 SRM setup. These testing results reveal that the proposed CCS MPTC method shows much lower torque ripples and current ripples in a wide speed range with a low computational burden than the existing finite control set MPTC methods. [ABSTRACT FROM AUTHOR]

A typical flywheel energy storage system (FESS) includes an electrical machine, a flywheel, and magnetic bearings, which are independent of each other. Therefore, the structure of FESS is complicated, which leads to the problems of high cost and low integration. This article presents a novel stator PM excitation solid rotor machine (SPE-SRM) for FESS, which integrates an electrical machine, flywheels, and a magnetic bearing. The design method of the SPE-SRM is presented specifically. First, the structure and operation principle of the SPE-SRM are illustrated. Second, the design and optimization of the flywheel-rotor are presented with considering of power, energy storage, and mechanical strength. Third, the magnetic equivalent circuit of the SPE-SRM is established to simplify the design. Besides, the armature reaction and leakage flux factor are investigated. Fourth, the performance indexes, including torque, suspension force, no-load back electromotive force (back-EMF), losses, and temperature rise are fully analyzed by the finite element analysis. Finally, a 22 kW prototype is manufactured and tested. The rationality of the concept and design is validated by experiments. The SPE-SRM has the merits of high integration, robust structure, and low cost, so it has the potential for wide application in FESS. [ABSTRACT FROM AUTHOR]

The trend in the industrial power electronics electrical drives is to reach high power density and high efficiency in variable load conditions at cost-effective unwasteful designs. Currently, motors with permanent magnets (such as IPMSM and PMaSynRM) are of great interest because of compactness, low losses, and high-torque capability. The performance of a drive system can be predicted with a motor electromagnetic authentic nonlinear model. In this article, a novel, fast, and precise motor model of PMaSynRM based on virtual reluctance (VR) is proposed. It takes into account the cross saturation, winding distribution, space harmonics, slotting effect, and stepped skewing. The VRs are identified by finite element analysis (FEA) and implemented in the time-stepping simulation. The flux inversion is not required. The proposed concept is useful in the rotating field or phase quantities (for open phase simulation). The model is also discretized for SiL and HiL applications. Finally, the validation in FEA and experimental setup was performed. [ABSTRACT FROM AUTHOR]

This article proposes a new “switched lumped reluctance network”-based equivalent circuit for a switched reluctance motor (SRM) under saturation. The proposed circuit incorporates the effects of the position-dependent switching of the phase windings and changing position of the rotor with respect to the stator. This feature enables the analysis of non-uniform and dynamic variation of flux in motor iron sections along with that in the air gap and their effects on the phase current. The proposed model, thus, emulates the operation of an SRM, more truly, through an equivalent circuit approach. The accuracy of the proposed model is verified by comparing the analytical results of five different stator–rotor sets (having different air gaps and tooth angular widths) with the finite-element method (FEM) simulated results and found to be in excellent mutual agreement. The static and dynamic performance obtained using the proposed model has been validated by experiments on a four-phase, 1-kW, 300-V, 1000-rpm SRM. [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 work contributes for the development of a low-cost reliable switched reluctance motor (SRM) drive for domestic water supply requirements. The work presents an adaptive gain super twisting sliding mode observer (AGST-SMO) for SRM drive with an enhanced transient behaviour. An online updation of sliding gains is proposed while satisfying the stability conditions of the observer. Performance of this observer is compared with the existing sliding mode observers. The developed SRM drive has a dedicated-port configuration to integrate the sources with SRM-pump and a domestic equipment, with reliable operation at low cost. For grid-side power quality issues, an improved linear sinusoidal tracer (ILST) is employed for the control of voltage source converter (VSC). ILST has inherent merits like active harmonics filtering, power factor correction, and fast dynamic response. The control of the drive system is validated by developing laboratory scale prototype and the system performance is examined at different conditions. The drive is suitable to fulfil water requirements for various applications at the consumer-end. [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]

Acquisition of the accurate phase currents is indispensable for the control and protection of switched reluctance motor (SRM) drives for electric transportation applications. Existing phase current reconstruction techniques for SRM are implemented under the current control techniques, which generate large torque pulsations. Therefore, the direct torque control (DTC) method can be adopted to minimize torque pulsations and to enhance transient performance in electrified vehicles. However, the existing current estimation methods cannot be applied to DTC strategies due to the simultaneous conduction of all phases at any switching instant. Furthermore, it offers a lower torque per ampere ($T/A$) ratio and draws a high source current. This article addresses the aforementioned concerns by proposing a cost-effective phase current reconstruction method with an improved DTC strategy for a 4-kW four-phase SRM drive. This method employs a 16-sector partition method with a new voltage vector selection by detecting zero-current regions of each phase. As a result, the long-tail currents can be avoided, thereby limiting the simultaneous conduction of all phases. The simulation and test results show that the proposed DTC has minimal torque pulsations, high $T/A$ ratio, low converter losses, and lower source current ripple in comparison to the existing DTC schemes under various operating conditions. Also, the proposed phase current estimation method effectively reconstructs the phase currents under both steady-state and transient operating conditions. [ABSTRACT FROM AUTHOR]

A novel electromagnetic force estimation using strain gauges attached to a laminated iron core method is proposed. Based on the strain gauge output, the electromagnetic force that occurs on the air-gap surface of the core is estimated with compensations for magnetostriction and nonuniform strain distribution. The proposed method is validated by comparing the electromagnetic force calculated in the finite element analysis and an experiment on a pair of C-shaped laminated iron cores. This article focuses on the force estimation in a pair of simple C-shaped cores, which are aimed at being a part of the stator and rotor of a switched reluctance machine. In future research, this basic approach will be extended to the estimation of the radial forces in switched reluctance motors to reduce the vibration and acoustic noise. [ABSTRACT FROM AUTHOR]

The present article proposes an effective model of synchronous reluctance machines. This model, called the Residual Magnetism (ReMa) model, takes into account not only residual magnetism within the rotor but also that within the stator. Electromotive forces generated by the ReMa model were composed of two frequencies and exhibited similar shapes as those measured in experiments. Resultant equations in a three-phase $(a,b,c)$ frame and in a Park reference frame $(d,q)$ were revealed. The comparison was made with the classical model of synchronous reluctance machine commonly used. Experimental tests were carried out to prove the effectiveness of the ReMa model which was also compared to a classical counterpart in the case where a synchronous reluctance generator was connected to a three-phase diode rectifier. [ABSTRACT FROM AUTHOR]

Vehicle to vehicle (V2V) energy sharing is emerging as an alternate solution to range anxiety and limited charging infrastructure challenges associated with electric vehicles (EVs). The existing off-board dc fast charging options for V2V application found in the literature are not effective due to the additional weight, size and cost of the external charger or interface. In this article, a new V2V interface is proposed in which both EV’s motor winding neutrals and negative rails of on-board drivetrains are directly connected to each other. This further helps in forming an integrated dual bidirectional dc–dc converter to control the direction of power flow. The proposed approach does not require reconfiguration of motor winding or mechanical clutch to arrest the motor from rotating and/or the reconfiguration of drivetrain inverter connections. The major hardware requirement for the proposed approach is, access to the already existing neutral connection of the EV motor phase windings. To achieve dc fast charging, all three-legs of voltage source inverter of energy Provider-EV are switched using interleaved pulsewidth modulation. Furthermore, finite element analysis is presented for 150 kW EV motor model and its performance validation with the high frequency dc current flowing in the motor windings during the V2V operation. A scaled lab prototype is developed to demonstrate the energy sharing between two Lithium-ion battery banks through the proposed direct V2V power transfer concept. [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]

Dc-field excited modular variable flux reluctance machines (VFRM) are passive salient-pole rotor and independent stator winding, which makes it suitable for aerospace applications. Fault-tolerant operation is commonly required to improve its reliability. Hence, the performance under winding open-circuit faults is analyzed and the fault-tolerant control strategy is presented to increase the output capacity in this article. First, the dc-rectified output voltages and power of the VFRM under both normal and open-circuit faults are derived. Then, phase angle control strategy of the fault-tolerant operation for a 12-slot-14-rotor-pole (12s14r) modular VFRM is proposed, where the control sequence is optimized to achieve the maximum output power of the generation system. Compared with the classical fault-tolerant method, a higher applicability of the proposed method in terms of the types of fault-tolerant operations can be achieved. The electromagnetic properties, including the armature current and the capacity of electrical power output, are analyzed with finite-element analysis. The effectiveness and feasibility of the proposed fault-topology and control strategy are verified by the 12s14r VFRM prototype in normal, fault, and fault-tolerant operation. [ABSTRACT FROM AUTHOR]

Rotor angle is essential in permanent-magnet (PM) brushless machines. Recently, an embedded magnetic encoder (EME) scheme, consisted of linear Hall sensors installing inside of the PM machines, has been proposed to sense the flux density and consequently provides rotor position. Compared with traditional optical encoder and resolver, the linear Hall sensor prevails over in both space and cost. The aforementioned scheme is employed successfully in rotor-PM machines, where a PM-excited field rotates at the synchronous speed. In this article, the feasibility of EME in stator-PM flux-switching machine is validated, where PMs are located in stator, resulting in a stationary PM field. The stator slots are selected as installation position of linear Hall sensors to avoid changing the existing structure of machines. The variation of linear Hall signal is due to the changing reluctance of rotor rather than rotating PMs. Then, a decoding algorithm is designed based on an add-up operation, a complex coefficient filter, and a synchronous reference frame phase-locked loop. Finally, experiments on a prototype machine are conducted to validate the effectiveness of EME scheme under both speed-varying and load-varying conditions. [ABSTRACT FROM AUTHOR]

In this article, a novel fault-tolerant design process of the spoke-type interior permanent magnet (IPM) motor is proposed to prevent the increase of cogging torque and torque ripple due to partial demagnetization fault and to minimize the motor size. First, unlike other research papers on the irreversible partial irreversible demagnetization of permanent magnet (PM), in this article, the effect of partial irreversible demagnetization faults on the cogging torque and torque ripple for the fault cases is investigated. Then, a novel fault-tolerant design process is proposed to solve the problem of partial demagnetization faults that increase the cogging torque and torque ripple. In the novel fault-tolerant design process, first, to solve the problem of increasing cogging torque and torque ripple due to the partial demagnetization fault, a process for implementing a uniform irreversible PM demagnetization is proposed. Second, to compensate for the motor torque constant decreased by degraded PM, which is caused by irreversible demagnetization of PM, a torque compensation coefficient is also proposed. The proposed fault-tolerant design process is applied to the motor design for the integrated electric brake (IEB) system that requires high torque density. In the optimal design process, Latin hypercube sampling (LHS), a kriging method, and a genetic algorithm are utilized. To verify the effectiveness of the proposed fault-tolerant design process, it is compared with the conventional optimized design results in which irreversible demagnetization of PM is not allowed at all to prevent the partial demagnetization faults. As a result of comparing the optimal design results, the proposed optimization model utilizing the fault-tolerant design process can significantly reduce the motor volume by 12.9%, compared to the conventional optimization model. [ABSTRACT FROM AUTHOR]

This paper presents a novel active power control scheme for SRMs that are used as S/G units at MEAs; the proposed method uses a vector-controlled SAF, facilitating the acceleration of the SRM during starter mode and the efficient power control of the SRG at various operational points during generator mode. Moreover, an energy storage unit is incorporated in the SAF, aiming at enhancing the SRM's starting torque production and taking full advantage of the SRG's energy generation capability, through the appropriate phases’ magnetization regulation that is imposed by the developed adaptive SAF vector control. In addition, the proposed scheme provides enhanced FRTC during both modes of operation. The mathematical analysis is verified through MATLAB/Simulink simulations, while the performance of the S/G concept under study is evaluated via real-time CHIL tests, with the use of the dSPACE 1202 (MicroLabBox) platform and the 16-bit dsPIC30F4011 microcontroller. [ABSTRACT FROM AUTHOR]

As one of the promising power interfaces between the energy storage components and the dc link, dual active bridge (DAB) converters have gained extensive researches. Its reliability and healthy operation under one or even multiple unexpected open-circuit faulty conditions have become one of the main design challenges. Conventional fault detection (FD) and fault isolation (FI) methods exhibit obvious limitations in terms of detection speed, number of FD signatures, universality, accuracy, computational burden, and implementation cost due to the added sensors. To fill in this gap, this article presents a robust, fast, accurate, and low-cost FD and FI method for DAB converters, which is applicable under various operational conditions. The proposed method will adopt the differential switch node voltage between the primary and secondary bridge of DAB converters as the universal fault signature for complete FD and FI. The corresponding fault diagnostic circuit is simple, compact, low cost, and easy in implementation. This sensorless fault diagnostic technique can detect the switch open-circuit fault within a quarter of a switching cycle and realize the fault isolation accurately. A DAB prototype with a fault diagnostic circuit was designed, and main experimental results under various faulty conditions were provided to validate the advantages of the proposed method. [ABSTRACT FROM AUTHOR]

Compared with the traditional control method, the direct torque control and direct force control method significantly reduces the torque ripple and the root-mean-square current of the phase winding in the single-winding bearingless switched reluctance motor. However, due to the unreasonable selection of voltage vectors and full cycle control, this method has some problems, such as too many control objects, excessive switching times, and low torque–ampere ratio. This article proposes an improved method for the abovementioned problems. First, the turn-on angle and conduction region of each phase winding are chosen as the control targets, and the operation principle is introduced accordingly. Second, according to the difference of the torque generated by the neighboring phases, the output torque can be distributed more properly to obtain the higher torque–ampere ratio in the commutation region. Finally, the sectors divided in the electrical space are reorganized and the corresponding voltage vectors are optimized. Experimental results show that the proposed method can secure lower torque ripples, fewer switching times, and copper loss. In addition, the torque–ampere ratio is improved as well. [ABSTRACT FROM AUTHOR]

Multiphase dc-excited Vernier reluctance machine (DC-VRM) exhibits the merits of robust structure, small torque ripple, and good fault-tolerant ability. Developing advanced sensorless drive methods can further promote its application in the safety-critical system. In this article, pulse injection sensorless drive methods are optimized in a six-phase DC-VRM parallel H-bridge drive system to strengthen their acceleration performance and fault-tolerant ability. The acceleration performance studied in this article corresponds to the acceleration speed during the startup stage. By the full-phase alternative pulse injection method (APIM), each phase can be excited independently to avoid mutual-inductance influence on position estimation, but this method suffers from a long communication delay and relatively poor acceleration performance. A reduced-phase APIM can reduce detection time, but the lack of detected phase may influence position estimation accuracy and fault-tolerant ability. To solve these problems, a novel vertical-axis synchronous pulse injection method is proposed and compared with previous methods in this article. The key is to inject detection pulses into vertical-axis phases simultaneously, thus reducing the detection time and improving the torque generation. It is proved that the influence of mutual inductance on position estimation can be ignored, and the detection accuracy and acceleration performance can be improved without deterioration of fault-tolerant ability. [ABSTRACT FROM AUTHOR]

In this article, a novel instantaneous electromagnetic torque modeling technique and current component distribution strategy are proposed for torque ripple reduction in three-phase flux modulated doubly-salient reluctance motor (FMDRM) drives. First, the analytical model of the instantaneous electromagnetic torque of a three-phase FMDRM is established, where the contributions of current components and harmonic inductance components are considered. The generation mechanisms of the average torque and torque ripple components are investigated in detail. Furthermore, based on the analytical instantaneous electromagnetic torque model, a simplified current component distribution strategy is proposed to further reduce the torque ripple of the FMDRM. Taking the torque ripple minimization as the optimization objective, the current advanced angle is optimized and the corresponding current component distribution strategy is carried out to reduce the torque ripple. The magnetic circuit saturation effect is also taken into account. Compared to the conventional scheme, the control freedom degree of the three-dimensional current controller in the FMDRM drive is fully utilized and the torque ripple of the FMDRM can be significantly reduced without the sacrifice of output torque capability and system efficiency. Experimental results are carried out on a three-phase 12/8 FMDRM prototype to verify the effectiveness of the proposed control strategy. [ABSTRACT FROM AUTHOR]

This article presents a maximum torque per ampere strategy for a five-phase synchronous reluctance drive. The approach is developed considering general machine parameters and is formalized as a constrained optimization problem. The optimal solution is found analytically by using Lagrange’s multipliers method and is based on the computation of the eigenvalues and eigenvectors of the inductance derivatives matrix. The proposed approach is evaluated both numerically and experimentally. It is also compared with other current references control strategies, effectively showing a reduction of the machine rms currents for the same developed torque. The same approach can also be extended to machines with a different number of phases. [ABSTRACT FROM AUTHOR]

This article proposes a novel dual-three-phase high-power high-speed permanent magnet assisted synchronous reluctance starter generator (PMaSynR SG) for aviation application, which has the characteristics of high efficiency, high power density, high reliability, and excellent antishort-circuit ability. The proposed PMaSynR SG can obtain higher efficiency and power density by embedding permanent magnet in the rotor topology compared with the synchronous reluctance generator, and has better antishort-circuit ability compared with the permanent magnet synchronous starter-generator. Moreover, design of dual-three-phase winding is adopted, which not only reduces the phase current, but also improves the reliability. In this article, the topological structure, characteristics and principle of PMaSynR SG are systematically studied at first. Second, a simplified dq-axis equivalent magnetic circuit model is established, and the expressions of dq-axis inductance and permanent magnet flux linkage are derived on the basis of the basic parameter selection. Then, combined with parameter sensitivity analysis, the influence law of rotor structural parameters on antishort-circuit ability and electromagnetic performance is revealed. Finally, a 40 kW 24 000 r/min PMaSynR SG is designed and manufactured. The simulation and experimental results show that the proposed PMaSynR SG has excellent electromagnetic performance with the power density of 3.1 kW/kg and the efficiency of 94%, while the short-circuit current is only 59% of its rated value. [ABSTRACT FROM AUTHOR]

High gradability and wide operating speed range are critical requirements for heavy-duty trucks and off-road electric vehicles. The motor power rating used for such applications can be reduced by selecting a motor with a wide constant power speed range (CPSR). However, permanent magnet synchronous motors (PMSMs) with wide CPSR have limited overloading capability. The operating speed range, as well as the overloading capability, can be improved by increasing the base speed of a low CPSR three-phase PMSM, which results in overdesign. Further, using multigear transmission to achieve a wide operating speed range with a low power motor increases system weight, drivetrain complexity, and maintenance requirement. This article proposes a dual three-phase interior PMSM with an unequal split winding configuration and zero degree winding displacement (uneq0-PMSM) to extend the constant power region and improve the overloading capability without any machine overdesign. The winding split ratio for the proposed configuration is decided to achieve the desired torque-speed characteristic shape for a given requirement. Further, a transition algorithm for smooth changeover between two-winding operation during low-speed and one-winding operation for high-speed is also proposed. The proposed concepts are experimentally validated on a 1.5-kW uneq0-PMSM with 1:3 winding split ratio. [ABSTRACT FROM AUTHOR]

This article focusses on power quality issues related with the operation of a wind energy conversion system employing a doubly fed induction generator (DFIG), integrated with a solar photovoltaic array, under unbalanced, and distorted grid conditions. The multiple-order DFIG electromagnetic torque ripples and grid active power ripples, resulting from the unbalanced and distorted grid, can be mitigated, however, at the cost of highly unbalanced and distorted currents. This article provides a possible solution towards a tradeoff by developing a flexible ripple minimization technique based on a cross-feedback extended second order generalized integrator for harmonics sequence separation (CextSOGI-HSS). The CextSOGI-HSS based current compensation enables a controlled minimization of ripple as per the customizable flexibility quotient. Furthermore, the current compensation technique employs an improved recursive least squares (IRLS) adaptive filtering algorithm for processing DFIG stator currents and local load currents. The IRLS algorithm improves grid currents harmonics spectra by filtering-out higher order harmonics from DFIG stator currents and nonlinear load currents, meanwhile, the effects of any load or stator currents unbalance on grid currents are also mitigated. Test results from a developed laboratory prototype confirm the efficacy of the presented flexible ripple minimization control technique. [ABSTRACT FROM AUTHOR]

This article proposes a multiobjective optimization design framework for a double stator brushless hybrid excitation motor (DSBHEM) to provide high torque, wide flux regulation ability and low torque ripple. The design variables are divided into sensitive level and insensitive level by sensitivity analysis. The response surface model (RSM) and nondominated sorting genetic algorithm 2 (NSGA2) are organically combined to generate a set of Pareto solutions for the sensitive level variables, from which the optimal values of the sensitive level variables are obtained. In addition, the optimal values of insensitive variables are obtained through single parameter scanning optimization, and a set of final optimal design variables are obtained. The electromagnetic performance of the initial design and the optimal design are compared with finite element analysis. Finally, a prototype is manufactured to verify the proposed concepts. [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]

This article reveals the flux leakage design and modeling principle of a flux leakage controllable permanent magnet (FLC-PM) machine by considering driving cycles. The key is to obtain the relationship between flux leakage characteristics and multiple operating conditions. Based on the flux leakage controllable concept, an FLC-PM machine with an artfully designed flux leakage region is proposed. The design principle of the machine is investigated by analyzing the magnetic circuit of the machine in multiple operating conditions. The flux leakage factor is introduced to characterize the variable magnetic field in multiple operating conditions. On this basis, the mathematical model of the FLC-PM machine is deduced, and the driving characteristics of the machine are studied in detail. In order to evaluate the presented principle of the FLC-PM machine, a prototype is manufactured for experiments. Through the theoretical analysis and experimental testing, it is verified that the proposed principle is feasible and effective. [ABSTRACT FROM AUTHOR]

In this article, an integrated drive converter of segmented double-stator switched reluctance machine (SDS-SRM) with isolation and nonisolation charging capabilities for electric vehicle (EV) is presented. The proposed converter can not only reduce the number of the power switches, but also implement multiple operation modes. In nonisolation charging mode, the motor windings and existing power switches constitute a buck/boost converter to charge the battery. The appropriate rotor positions are obtained to achieve torque-free control, and the interleaved phase currents control method is introduced to reduce the charging current ripples. In isolation charging mode, the inner-stator is powered by the utility grid to drive the middle-rotor, and converts electrical energy into mechanical energy, while the outer-stator is operated in generation mode to convert mechanical energy into electrical energy. The SDS-SRM is served as a rotating transformer to transfer the electric power to charge the battery with the galvanic isolation function. A low power proof-of-concept prototype platform is built and experiments are carried out to verify the effectiveness of the proposed integrated drive converter and the corresponding control schemes. [ABSTRACT FROM AUTHOR]

This article presents an accurate analytical model (AM) for synchronous reluctance machine (SynRM) that incorporates the effect of stator slots on the air gap flux density and torque waveforms. From the formulation of magnetic potential in the air gap for both the stator and rotor, the flux density is obtained, considering the first harmonic of the flux density and the electric loading, the average torque is calculated using the Lorentz’s force. The ripple torque is obtained from the energy stored in magnetic circuit. The method is developed for a rotor with one flux barrier per pole and then extended to a larger number of barriers. To validate the results obtained by the AM proposed finite element analysis have been carried out. Several comparisons have been derived considering different rotor positions as well as different harmonic orders, and the pros and cons of the method are highlighted. The model performs fast and can predict results with high accuracy, and can be adopted to speed up the preliminary design and optimizations of this type of motors, with respect to finite element. In addition, from the analytical expressions it is possible to obtain all the correlations between electrical, magnetic, and geometrical characteristics of the machine, with the advantage of enabling a faster machine design. [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]

In current engineering, the skewing slots approach is commonly used for permanent magnet synchronous motor (PMSM) to reduce torque ripple and electromagnetic vibration. However, this approach may limit the axial length of the motor and increase the manufacturing cost. This article studies a segmented rotor with different pole widths approach to mitigate torque ripple and electromagnetic vibration for PMSM, which has a lower implementation cost and facilitates mechanized production. The mapping relationship between geometric dimensions and torque performance is obtained, and the optimal dimensions are determined. An 8-pole/48-slot V-shaped PMSM is taken as the original motor, and the influence of engineering error on the torque performance of the presented approach is discussed. The electromagnetic performances and vibration responses of the motor with the presented approach are compared with that of the skewing slot motor to verify the effectiveness of the presented approach. Finally, prototypes are built, and intensive experimental tests are carried out to verify the analysis and comparison. [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]

In this article, we propose an interactive visualization method for motor design. We have proposed a visualization system for education using augmented reality (AR) and virtual reality (VR). As a further development of this, we are working on motor design as an industrial application. There are two issues in achieving high-speed interactivity. One is a fast mesh modification method in finite element analysis, and the other is a fast solving method. We propose a high-speed mesh modification method that utilizes regularly arranged grid points and coordinate transformation. In the proposed design system, the user can immediately observe the analysis result of the design change. Furthermore, if the proposed system is executed in cooperation with the projector, designers can change the design of the motor with their fingers and discuss it on the board. Furthermore, since this system can be executed on a Web browser, it can also be executed on a smartphone or tablet PC. [ABSTRACT FROM AUTHOR]

This article studies the transmit beamforming security in the dual-functional radar-communication (DFRC) system, where the radar beam also serves as the artificial jamming to suppress potential eavesdropper channels. Unlike previous researches, which assumed that the lone target might be a potential eavesdropper on the adversary side, this paper analyses a more generic scenario in which the eavesdroppers’ channel state information (CSI) is unknown. The eavesdropping rate should be limited to guarantee transmission confidentiality, which is intractable owing to the unknown CSI. To address this issue, we present the long-term eavesdropping signal-to-interference-plus-noise ratio (SINR) as a more tractable security metric. Based on the long-term eavesdropping SINR, the sum rate maximization (SRM) and jamming power maximization (JPM) transmission scheme are investigated. For the SRM scheme, we propose a zero-forcing (ZF) suboptimal algorithm to solve the non-convex fractional programming (FP) problem, and for the JPM scheme, the resultant problem is solved via the semidefinite relaxation (SDR) technique. Finally, numerical results validate the effectiveness of the proposed beamforming approaches. [ABSTRACT FROM AUTHOR]

This article proposes an improved method for the position signal evaluation of a switched reluctance motor (SRM) drives. It can perform accurate position signal reconstruction based on the inductance, and greatly increase the fault tolerance of SRM in complex environments. It includes the position signal fault diagnosis (PSFD), position signal estimation, and fault-tolerant control (FTC). First, the installation and principle of the position sensor is introduced to show the function of the position signal in SRM drive system. Then, to overcome the limitation of application range of the conventional diagnosis method, a new PSFD method based on grey prediction model is proposed. Besides, a position estimation method based on the inflection point of the inductance is proposed. According to the estimated position, FTCs are carried out when position sensors are faulty. Finally, experiments are carried out to validate the effectiveness of the proposed position signal fault-tolerant control method based on a 12/10 six phase SRM. [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]