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Today, due to shop-floor uncertainties and widespread cross-enterprise collaborations, manufacturing systems of enterprises are increasingly demanded to be agile, adaptive, flexible and interoperable. Process planning systems are mission-critical constituent components of manufacturing systems in machining job shops of small and medium-sized enterprises in the machining and metal cutting sector. Cloud-based adaptive distributed process planning, which includes global supervisory planning in the cloud and local operation planning based on function block and cloud technologies, provides an effective approach for enhancing agility, adaptability, flexibility and interoperability of manufacturing systems. [ABSTRACT FROM AUTHOR]

This article deals with the problem of finding the maximum number of maximum cliques in a weighted graph with all edges between vertices from different d-division of a graph with the minimum total weight of all these cliques, and the problem of finding the maximum number of maximum cliques in a nonweighted graph with not all edges between vertices from different d-division of the graph. This article presents new ant algorithms with new desire functions for these problems. These algorithms were tested for their purpose with different changing input parameters, the test results were tabulated and discussed, the best algorithms were indicated.

Abstract Five‐phase permanent magnet synchronous machine (PMSM) can operate under open‐circuit faults with the appropriate current regulations. However, the traditional current regulations based on the five‐phase half‐bridge inverter have to satisfy the constraint of zero neutral point current, which limits the fault‐tolerant performance of the machine. Thus, this paper investigates the current regulation based on the five‐phase six‐leg (FPSL) inverter, which relieves the zero‐neutral point current limitation, and both current regulations considering the maximum torque (MT) and minimum copper loss (MC) are derived under different open‐circuit conditions. The cost of the system has increased, but with the new regulations, better fault‐tolerant operation capability of the machine can be obtained under all kinds of open‐circuit faults. Moreover, with the introduction of the neutral point current, the machine can work under triple‐phase open‐circuit faults. In conclusion, the proposed control scheme based on the FPSL inverter expands the fault‐tolerant operation capability of the five‐phase PMSM. The experiment results prove the effectiveness of the proposed current regulation on increasing average torque or reducing copper loss under fault‐tolerant operation.

Five‐phase permanent magnet synchronous machine (PMSM) can operate under open‐circuit faults with the appropriate current regulations. However, the traditional current regulations based on the five‐phase half‐bridge inverter have to satisfy the constraint of zero neutral point current, which limits the fault‐tolerant performance of the machine. Thus, this paper investigates the current regulation based on the five‐phase six‐leg (FPSL) inverter, which relieves the zero‐neutral point current limitation, and both current regulations considering the maximum torque (MT) and minimum copper loss (MC) are derived under different open‐circuit conditions. The cost of the system has increased, but with the new regulations, better fault‐tolerant operation capability of the machine can be obtained under all kinds of open‐circuit faults. Moreover, with the introduction of the neutral point current, the machine can work under triple‐phase open‐circuit faults. In conclusion, the proposed control scheme based on the FPSL inverter expands the fault‐tolerant operation capability of the five‐phase PMSM. The experiment results prove the effectiveness of the proposed current regulation on increasing average torque or reducing copper loss under fault‐tolerant operation. [ABSTRACT FROM AUTHOR]

AbstractRobotic Hand Grasping is a challenging task that is studied by different researchers, with contributions made to topics such as grasping quality measuring, synthesis, and mathematical models. However, these works usually consider grasping of only one object at time, which is not applicable when the hand must carry multiple objects. Multiple objects grasping problem can be approached as a packing problem, which consists in filling a container with objects of a determined geometry, using the space available in the most efficient way. The aim of this work is to obtain a design methodology for a two-finger gripper that optimizes the grasping capacity of slender cylindrical multiple objects, applying packing problem concepts. This case is of practical importance in grapple claws used in forest harvesting for picking logs. A mathematical model is presented that allows to obtain an optimized geometric configuration of the grapple claw for maximum grasping capacity and packing density for given numbers and sizes of logs. This model is analytically solved for the maximum radius of a set of logs that can be grasped. Alternatively, for a number of logs with a given diameter, the geometric dimensions of an optimized grapple claw can be obtained. The solutions are evaluated using packing density and Active Force Closure (AFC) as quality metrics, to show the benefits of adding them as design criteria in the design multiple objects grapple claws. [ABSTRACT FROM AUTHOR]

In the context of developing a machine to automatically crochet fabrics, a suitable design tool tailored to the new technology and enabling its application is crucial. The paper offers first insights into the prototype of the crochet machine and presents the approach of such a design tool implemented in Python for creating, modeling and generating the machine instructions. With a graphical user interface (GUI), a flat crocheted fabric can be designed by arranging international crochet symbols for slip stitch (SL), single crochet (SC) and half double crochet (HDC). Built-in error checking mechanisms, following the rules of crochet and the machine’s constraints, will aid inexperienced crocheters in this process. Based on the resulting computer representation as an array containing short strings for the respective stitches, a topology-based 3D model at the meso scale is automatically created as a preview of the designed crocheted fabric. Also, machine instructions to automatically crochet the fabric with the crochet machine prototype are generated by mapping the computer representation of the stitches to macros of G-code and appending them in a valid order. The straightforward design tool shows the capabilities of the crochet machine and is extensible for further enhancements. Through modeling, the structure of the machine-crocheted fabrics is presented for the first time. In comparison to manually crocheted fabrics, the machine-crocheted ones exhibit a technical front and back, since stitches are formed by the machine only from one side.

Abstract Deep Reinforcement Learning (DRL) has demonstrated its great potential for Adaptive Traffic Signal Control (ATSC) tasks at single‐intersection. In the transportation network multi‐agent environment, cooperative learning among multi‐agents has become a hot research topic. Based on the distributed control model, this paper presents a hybrid reward function model for the dynamic density method of intersections, which emphasizes the priority of emergency vehicles (EMV) while maximizing the traffic efficiency of social vehicles, and solves the problem of sparse reward due to the ambiguous guidance relationship between the multi‐agent Deep Reinforcement Learning (MDRL) state and reward function of the urban road network scenario. On the other hand, based on multi‐agent A2C (MA2C) algorithm, this paper presents Shared Experience MA2C (SEMA2C) between agents. In the transportation network, each intersection represented by an agent has similar task objectives. SMEA2C algorithm takes the current agent as the main body of self‐learning, and utilizes the principle of importance sampling to learn from the experience data of the agents located at adjacent intersections. The experimental results show that the proposed SEMA2C performs well in multi‐agent traffic signal control tasks, and has greater advantages than the similar algorithms.

The paper presents a novel control method based on a dual thread speed controller with modified multi-oscillatory control for speed ripple reduction in a switched reluctance machine-based drive. The method is based on on-line phase current shaping. The paper describes a dual thread angle-sampled multi-oscillatory control (ASMOSC) theory for speed ripple reduction of a switched reluctance machine under variable speed. Description of the entire cascaded speed control system with linear controllers is also provided, along with an implementation description for ASMOSC. This includes practical hints on how to apply the control system to a dual core microcontroller. The frequency-domain stability analysis for a designed control system under variable speed conditions is presented. The overall performance of the control system is verified numerically and experimentally on a laboratory setup with an 4-phase 8/6 SRM-based drive. • The speed ripple reduction control method for a switched reluctance machine is presented. • Angle sampled multioscillatory controller is used for on-line speed ripple rejection. • A new dual thread speed controller with angle sampling is described. • Practical hints on how to apply the dual thread control system are provided. • The system performance is verified numerically and experimentally on a 4-phase 8/6 switched reluctance machine. [ABSTRACT FROM AUTHOR]

Deep Reinforcement Learning (DRL) has demonstrated its great potential for Adaptive Traffic Signal Control (ATSC) tasks at single‐intersection. In the transportation network multi‐agent environment, cooperative learning among multi‐agents has become a hot research topic. Based on the distributed control model, this paper presents a hybrid reward function model for the dynamic density method of intersections, which emphasizes the priority of emergency vehicles (EMV) while maximizing the traffic efficiency of social vehicles, and solves the problem of sparse reward due to the ambiguous guidance relationship between the multi‐agent Deep Reinforcement Learning (MDRL) state and reward function of the urban road network scenario. On the other hand, based on multi‐agent A2C (MA2C) algorithm, this paper presents Shared Experience MA2C (SEMA2C) between agents. In the transportation network, each intersection represented by an agent has similar task objectives. SMEA2C algorithm takes the current agent as the main body of self‐learning, and utilizes the principle of importance sampling to learn from the experience data of the agents located at adjacent intersections. The experimental results show that the proposed SEMA2C performs well in multi‐agent traffic signal control tasks, and has greater advantages than the similar algorithms. [ABSTRACT FROM AUTHOR]

Principle of sequential excitation for stator windings of switched reluctance motor (SRM) causes many problems including torque ripples and substantial requirement for rotor position sensing. This paper presents an online torque sharing function (TSF) to minimize the undesirable torque ripples in SRM which operates under sensorless drive system. In classical TSF, variance between incoming and outgoing motor torque responses makes tracking of motor torque to reference torque cannot be achieved. Moreover, the TSFs are mainly designed for operating at rated speed. As motor speed changes, the torque ripples increase because the commutation period (CP) becomes inappropriate for commutation process. The proposed TSF is designed to guarantee the good matching between the motor torque response and TSF reference. So, a linear function is chosen as a torque reference for the incoming phase while an exponential function is selected for the outgoing phase. Additionally, the online tuning of commutation period is employed in the proposed hybrid TSF. The sliding mode observer (SMO) based model is formulated for rotor position and speed estimations purpose. The performance of the modified TSF is validated throughout computer simulations and experimental results. Furthermore, the comparisons between the proposed TSF and conventional TSF are carried out.

The technology of Internet of Things (IoT) can be integrated with systems of electrical machines, for electric drives and wind and solar generation systems, and advance controlling and monitoring. This work presented recent research and progress of electrical drives with IoT technology, regarding design, operation, and trial of the control system for induction motors (ΙΜ). Also, the developed software code and hardware units for speed control were detailed and the results obtained from tests of performance of the ΙΜ integrated with IoT were described. With the IoT integration set-up, the operator can control the frequency values, obtain real-time feedback of the process, and monitor the system during varying loads in steady state. The operation of the ΙΜ system driven by inverter and its monitoring over IoT was proven to have high-accuracy speed control and increased efficiency at supersynchronous speeds. Thus, IoT establishes potentials to become a multipurpose tool in the industrial control of electric drives. This paper established one case study of an IoT set-up and control technique for IM, which is suitable for energy engineering experts in the field of IoT control of industrial equipment. [ABSTRACT FROM AUTHOR]

Abstract In order to deepen the understanding of power electronics circuits, in this study, a teaching method of adding simple small applications of circuits on the basis of basic verification experiments is proposed. Teachers teach basic principles and applications of circuits, and students conduct basic verification experiments of circuits in the laboratory. Simple application experiments are added after the verification experiments. The full‐bridge DC‐DC converter circuit is taken as an example to carry out practical teaching. After completing the function of the full‐bridge DC‐DC converter circuit, a load of DC motor is used. The full‐bridge DC‐DC converter circuit is used to control the speed of the DC motor so as to realise the simple application of the full‐bridge DC‐DC converter circuit with a motor speed control function. By comparing the experimental realisation rate, the correct rate of thinking questions and the in‐depth understanding of the application theory of two experimental classes, namely the class with simple applications and the class without simple applications, it is shown that the students with simple application experiments improved the correct rate of thinking questions and deepened their understanding of the applications. Compared with the situation in which most students in the class that did not conduct the application experiment did not know the application principle in detail, most students in the class that conducted the application experiment had a deep understanding of the applications. Through the questionnaire survey of students, it is observed that the method proposed in this study could deepen the understanding of circuits and the students had a simple and preliminary understanding of the applications of power electronics technology. It improved students' interest in the course and their practicing ability. The proposed teaching method had a good effect.

The number of auxiliary electric drives can exceed 100 for luxury cars. Due to their ever‐increasing prevalence, the electromagnetic emissions (EME) of these drives are becoming increasingly important. This work explores the influence of four different stator winding topologies on the electromagnetic emissions and the efficiency performance of fractional horsepower (FHP) brushless direct current (BLDC) drives. Two monofilar windings with a wire diameter of 0.15 and 0.27 mm, an untwisted bifilar winding, and a twisted bifilar winding are inspected. The parasitic stator to winding coupling capacitance is the motor's main source for common mode currents and thus, for radiated emissions. A three‐media capacitance model is introduced to allow estimating this coupling path in the design phase of the motor. Twisting the phases of a bifilar winding reduces the excitation of this path. Therefore, the radiated emissions are reduced by 5 dBμV/m ${\mathrm{B}}_{\mu \text{V/m}}$. The stator winding topology also affects the winding resistance and thus the efficiency. The monofilar winding with a wire diameter of 0.27 mm shows the lowest level of consumed power, followed by the monofilar winding with a wire diameter of 0.15 mm, the untwisted bifilar winding and the twisted bifilar winding. [ABSTRACT FROM AUTHOR]

Abstract In order to solve the problem of lacking active learning and independent problem‐solving ability in the verification experiment, an experimental teaching method of designing experiment from the perspective of the teacher is proposed, in which the roles of students and teachers are changed. Students are made familiar with the platform through a verification experiment in which the teacher gives the experiment guidebook and provides guidance. Then, the target of another experiment is given. The students design the experiment from the perspective of the teacher, and write the experiment guidebook, including the experimental objectives, the experimental contents and the implementation methods. Then the students do the experiment. The power electronics experiment course is taken as an example to introduce the proposed method. The Sinusoidal Pulse Width Modulation (SPWM) inverter circuit experiment is taken as the verification experiment. After the students are familiar with the platform functions, they design a DC motor speed regulation experiment with a full bridge DC‐DC circuit, write a guidebook, and complete the experiment according to the steps in the guide book. Finally, according to the success rate and the correct rate of the results, most students can complete the design experiment from the perspective of the teacher, and the answers to the thinking questions are basically correct. According to the questionnaire survey, the method proposed improves the students' ability of autonomous learning and problem‐solving with good results.

Abstract To improve the efficiency, a 13 kW used vehicle permanent magnet synchronous motor was remanufactured, whose stator core was replaced by a combination of amorphous alloy laminations and silicon steel laminations. But the speed regulation ability with field weakening of the remanufactured motor limits its development towards high speed direction. Taking the remanufactured motor as the object, based on the theory of speed regulation with field weakening, the maximum speed range was improved by increasing direct‐axis inductance, and the structural optimization parameters affecting the direct‐axis inductance were analysed. The two‐dimensional inductance superposition method was proposed to calculate the direct‐axis and quadrature‐axis inductance of the remanufactured motor, and its accuracy and feasibility were verified by finite element simulation. The segmented structure of the V‐type permanent magnet was used, and the motor structure was optimised from three aspects: the width and position of magnetic bridge and the magnetic pole implantation depth. The orthogonal experiments were designed to determine the best parameter combination. The results show that the direct‐axis inductance of the optimised remanufactured motor is increased by 16.33%, and the performance of speed regulation with field weakening is improved significantly.

Abstract The operation of parallel‐connected servo drives has the advantages of increasing the torque (hence the power) capacity, reliability, redundancy and modularity. However, smaller discrepancies of the system clocks of the independent microcontrollers, asynchronous pulse width modulation (PWM) carrier signals and hardware differences can make the output voltages of the parallel modules non‐identical, which results in circulating currents. These circulating currents limit the parallel operation, introduce additional power dissipation, cause unbalanced power distribution and degrade the control performance. To eliminate the circulating currents separated DC supplies, coupled inductors (CIs), PWM techniques, modified control techniques etc. are proposed in the literature. In this study, a fault‐tolerant parallel‐connected gallium nitride enhancement‐mode high electron mobility transistor voltage source inverter‐based servo drive scheme that eliminates the need for CIs and separate DC supplies and also enables the use of a standard proportional‐integral current control and a standard space vector PWM approach is proposed and tested. To evaluate the performances of the proposed scheme, up to six servo drives (limit‐6 × 7 Arms) are connected in parallel and tested under various conditions with a 24 V permanent magnet synchronous motor (nominal‐61.9 Arms). The results show that the parallel operation not only increases the torque capacity of the system but also increases modularity, flexibility, reliability and also redundancy.

Abstract The voltage‐controlled doubly fed induction generator (VC‐DFIG) is widely studied because of its self‐synchronous control characteristics and its ability to actively support the grid voltage and frequency. However, the VC‐DFIG is a multi‐loop and cascade‐controlled system, and the bandwidth design of each control loop is difficult. When the power instruction and grid frequency disturbances occur, the improper bandwidth designs will cause severe oscillation and overshoot. In this study, the Thevenin equivalent voltage model of DFIG is derived, combined with the characteristics of voltage control, and the control structure of VC‐DFIG is constructed. On this basis, a small signal model of active power dynamic response is established, which includes the characteristics of the voltage control loop and active power loop. For the parameter robustness and dynamic response of VC‐DFIG, the frequency damping control strategy and the lead‐lag correction control strategy are proposed. Finally, the enhanced VC‐DFIG technology was realised through the 2.0 MW DFIG experimental platform, and the effectiveness of the two proposed control strategies were verified.

Abstract This study proposes an integrated non‐linear modelling method for an electromechanical actuation system directly driven by the switched reluctance motor (SDEMA). The mathematical model of the SDEMA system is established by energy analysis and calculation according to the proposed method, which omits the complex analysis of force or torque transmission in the cascade modelling method. By using the Lagrange–Maxwell equation and establishing the energy models of non‐linear factors that include the friction, backlash, and flexibility, both the electromechanical coupling effects and the non‐linear factors of the SDEMA system are considered simultaneously in the proposed method. To verify the feasibility and effectiveness of the proposed method, three modelling methods of the SDEMA system are comparatively studied through the simulations and experiments. The results of the simulations and experiments indicate that the proposed integrative non‐linear model can reflect the dynamic performance of the SDEMA system more accurately.

Abstract This study presents an accurate motion control scheme using a modified non‐linear disturbance torque observer for a rail traction system driven by a dual brushless AC (BLAC) motor. The target application has two BLAC motors mounted on the top surface of the rail. The mover translation along the rail is handled solely by the traction motors without any external sensor. In the low‐speed range, however, the conventional disturbance torque observer is unstable due to the resolution of the Hall sensor and speed detection delay. To solve this instability problem, a simple weight function with the synchronisation of torque current and the delayed speed feedback is added to the proposed torque observer. This way, zero output can be created in the selected speed region for stabilisation and torque current can be compensated. Furthermore, simple balance error compensation to synchronise both motors is added to the proposed speed and position model reference adaptive control scheme. The experiments were performed to verify the proposed control method. The results show advanced performance with reduced position and balance errors between the two BLAC motors and an improved overall control performance of the rail mover.

Abstract During the operation of a permanent magnet synchronous motor (PMSM), the control system is impacted by changes in the internal parameters and by external disturbances, resulting in reduced accuracy. The robustness and anti‐interference ability of a PMSM can be improved using a speed loop‐current loop integrated predictive control method. First, a PMSM mathematical model is constructed considering parameter changes and external disturbances. Second, using only the input and output of the speed loop and the current loop, without involving any motor parameters, an ultra‐local model‐free predictive control model of the speed loop and the current loop is built; this model has a lower sensitivity to parameter changes. Finally, to improve the tracking accuracy for speed and current, an extended state observer (ESO) and a disturbance observation compensator (DOC) are established to observe the total disturbance of system in real time and perform feedforward compensation. The experimental results show that the control model has strong robustness and anti‐interference ability, high stability, high speed, and capable current‐tracking performance.

Abstract In the traditional finite control‐set model predictive direct speed control (FCS‐MPDSC), the coupling items in the current equation have been ignored because of predictive complexity, leading to imperfect prediction accuracy and control performance. Meanwhile, the current error and speed error are both included in the weighted sum cost function. The two types of errors lead to the difficulty of weight coefficients' distribution, which can only rely on subjective experiences. Thus, an FCS‐MPDSC strategy based on the 2nd‐Taylor‐series model with quadratic cost function is proposed. The dynamic performance has been greatly improved because the input variables of the Taylor series model are unified as the basic voltage vector with the same control period. And the static error is also reduced as the weight coefficient matrix of the quadratic cost function is solved offline. On this basis, the verification experiments are carried out. The results show that a better dynamic and static performance is achieved at the same time by the proposed strategy.

In order to deepen the understanding of power electronics circuits, in this study, a teaching method of adding simple small applications of circuits on the basis of basic verification experiments is proposed. Teachers teach basic principles and applications of circuits, and students conduct basic verification experiments of circuits in the laboratory. Simple application experiments are added after the verification experiments. The full‐bridge DC‐DC converter circuit is taken as an example to carry out practical teaching. After completing the function of the full‐bridge DC‐DC converter circuit, a load of DC motor is used. The full‐bridge DC‐DC converter circuit is used to control the speed of the DC motor so as to realise the simple application of the full‐bridge DC‐DC converter circuit with a motor speed control function. By comparing the experimental realisation rate, the correct rate of thinking questions and the in‐depth understanding of the application theory of two experimental classes, namely the class with simple applications and the class without simple applications, it is shown that the students with simple application experiments improved the correct rate of thinking questions and deepened their understanding of the applications. Compared with the situation in which most students in the class that did not conduct the application experiment did not know the application principle in detail, most students in the class that conducted the application experiment had a deep understanding of the applications. Through the questionnaire survey of students, it is observed that the method proposed in this study could deepen the understanding of circuits and the students had a simple and preliminary understanding of the applications of power electronics technology. It improved students' interest in the course and their practicing ability. The proposed teaching method had a good effect. [ABSTRACT FROM AUTHOR]

Abstract In normal operation mode, sensorless speed‐controlled motor drives should be more reliable, less expensive and less bulky than their counterparts with a speed sensor. The sensorless drive structure allows avoiding the electromagnetic and vibratory sensitivity of the mechanical sensor, the additional connecting circuits, additional space for the sensor, its price and maintenance requirements. However, in postfault operation mode, the robustness of speed sensorless control strategies has been poorly addressed in the study. Accordingly, this study deals with an experimental study of the robustness and the availability of speed‐controlled induction motor (IM) drives without speed sensor in the presence of inverter open‐switches faults. For that purpose, a super twisting algorithm‐based observer for motor speed estimation is proposed for experimental investigation. Experimental results are performed upon 3‐kW IM drive by using dSPACE digital signal processing controller board. Experimental investigations evaluate the performances of the method used for the control without speed sensor in prefault, postfault and regeneration operation modes.

Abstract Model predictive fault‐tolerant current control (MPFTCC) of permanent magnet synchronous generator (PMSG) drives can make a valuable contribution to improving the reliability and availability levels of wind turbines, because back‐to‐back (BTB) converters are prone to failure. However, MPFTCC suffers from excessive computational burden, because the BTB converter is treated as one system where all feasible voltage vectors (VVs) are used for prediction and evaluation. Accordingly, a computationally efficient MPFTCC algorithm for a PMSG drive is developed and proposed with the ability to handle insulated‐gate bipolar transistor open‐circuit faults. The candidate VVs of both machine‐ and grid‐side converters are separately predicted and evaluated, which significantly reduces calculation effort. The proposed reconfigurable converter is a five‐leg power converter with a common leg that connects the generator first phase to the grid three‐phase, ensuring proper postfault reconfiguration of the grid‐side inverter. Moreover, a three‐switch rectifier is adopted to achieve fault tolerance of the PMSG‐side rectifier. Performance of the considered MPFTCC strategies is evaluated by experimental means.

Abstract Permanent magnet synchronous motor (PMSM) shows the great potential for use in direct drive system because of its excellent low‐speed direct‐drive capability. However, it suffers from the adverse effect of the cogging torque in comparison with the asynchronous motor. Therefore, reducing the cogging torque, especially the external‐rotor PMSM (ERPMSM) for belt conveyor application, is necessary for enhancing the stable operation and precise positioning performances of the belt conveyor.Herein, a novel tangential magnetization low‐speed high‐torque ERPMSM is proposed and analysed. Furthermore, the expression of the cogging torque of the proposed ERPMSM is derived by energy method. Based on the special structure of the ERPMSM, a new method for cogging torque reduction is introduced. The comparative FEA results for four ERPMSM models are presented to verify the accuracy and effectiveness of this method. The accuracy of the cogging torque FEA results is confirmed by a prototype. Finally, the influence of this method on ERPMSM performance is also analysed carefully in this paper.

Abstract In this work, the electromagnetic torque and the unbalanced magnetic force (UMF) in eccentric consequent pole PM (CPPM) machines are investigated. For this investigation, in the first part of the paper, an exact analytical model is provided for the CPPM machine by solving the Poisson equation in the eccentric and salient air gap. In the analytical modelling process, the concept of equivalent magnetizing current (EMC), the subdomain technique, and a bilinear transformation are applied. The obtained model is verified by means of FEA. In the second part of the paper, by using the developed model, the relationship between the machine electromagnetic torque and the UMF to the d‐ and q‐axis components of the armature current is studied. It is shown that in CPPM machines, the influence of the q‐axis current on the electromagnetic torque is much higher than the effect of the d‐axis current. On the other hand, the eccentric machine UMF is strongly dependent on the d‐axis armature current while the variation of the UMF due to the changes in the q‐axis current is small. Therefore, in eccentric CPPM machines, UMF could be suppressed by injecting a negative d‐axis armature current (flux weakening).

Abstract In the last few years, the reduction of the dependency on rare‐earth magnets has been one of the main concerns for electrical machine manufacturers. Synchronous reluctance machines (SynRMs) and ferrite permanent magnet‐assisted synchronous reluctance machines (PMa‐SynRMs) are emerging as alternatives to permanent magnet synchronous machines (PMSMs) in several applications. In low‐speed high‐torque applications, PMSMs with large amounts of rare‐earth magnets are commonly employed. Thus, it is of particular interest to replace PMSMs by SynRMs or PMa‐SynRMs. This article studies the feasibility of using SynRMs and ferrite PMa‐SynRMs for a direct‐drive elevator system. The challenge lies in obtaining performance characteristics comparable to those of PMSMs, but without resorting to the use of rare‐earth permanent magnets. The main criteria for designing SynRMs and PMa‐SynRMs for low‐speed high‐torque applications are presented. Afterwards, a SynRM and a ferrite PMa‐SynRM are designed for 160 rpm 200 Nm rated conditions, and a performance and cost comparison between these machines and a commercial PMSM is conducted.

The technology of Internet of Things (IoT) can be integrated with systems of electrical machines, for electric drives and wind and solar generation systems, and advance controlling and monitoring. This work presented recent research and progress of electrical drives with IoT technology, regarding design, operation, and trial of the control system for induction motors (ΙΜ). Also, the developed software code and hardware units for speed control were detailed and the results obtained from tests of performance of the ΙΜ integrated with IoT were described. With the IoT integration set-up, the operator can control the frequency values, obtain real-time feedback of the process, and monitor the system during varying loads in steady state. The operation of the ΙΜ system driven by inverter and its monitoring over IoT was proven to have high-accuracy speed control and increased efficiency at supersynchronous speeds. Thus, IoT establishes potentials to become a multipurpose tool in the industrial control of electric drives. This paper established one case study of an IoT set-up and control technique for IM, which is suitable for energy engineering experts in the field of IoT control of industrial equipment.

Abstract Generalized predictive control (GPC) is promising for permanent magnet synchronous machine drive systems, due to its outstanding dynamic performance and disturbance rejection capability. However, the speed measurement noise introduced by the encoder and the unmodelled disturbances introduced by the non‐ideal machine characteristics deteriorate the performance of GPC. The noise and disturbance issues are studied in detail, and an enhanced GPC method is proposed to address them. For the noise issue, the mathematical model of the speed measurement noise is derived, and the noise spectra at different speeds are analysed. Then, a novel GPC with internal low‐pass filter is proposed to reject the influence of the noise. For the disturbance issue, the influence of the unmodelled disturbances on the speed performance is assessed when applying different noise rejection methods, and a resonant controller‐based speed ripple mitigation method is proposed and integrated to the GPC. Experimental results show that the proposed methods can effectively deal with the noise and disturbance issues, as well as providing better dynamic performance than the conventional PI based speed control.

Abstract Predictive current control (PCC) is a promising technique for adjustable speed drives due to its intuitive features such as quick response, easy inclusion of non‐linearities and constraints as well as multi‐variable operation. The conventional predictive current control (C‐PCC) employs a cost function to choose the optimum vector, which reduces the error between the reference and the predicted current. Even though the C‐PCC can achieve excellent dynamic performance with a single active voltage, the steady‐state performance is affected with larger torque and flux ripples. When two voltage vectors are applied in a control interval, the steady‐state performance is improved. This paper proposes a modified duty‐based PCC for permanent magnet synchronous motor (PMSM) drives, employing an active and null vector in control interval, where the duration for which the optimal active vector is applied is based upon a simple error based calculation. The proposed duty calculation requires a simple constant and eliminates the need for current slope calculation, which results in parameter insensitive operation. The proposed method is compared with C‐PCC and recently published works based on duty calculation. The simulation and hardware experiments conducted on a PMSM drive confirm the effectiveness of the proposed method with reduced torque and flux ripples.

Abstract This paper proposes a robust predictive resonant current control to improve the dynamic and anti‐disturbance performance of the permanent magnet synchronous linear motor (PMSLM). First, the disturbance caused by parameters variation is considered in modelling PMSLM. Based on this model, a robust predictive current control (RPCC) with mover current and disturbance estimation is derived, which is used to simultaneously overcome the time‐delay and estimate the parameters disturbance. Then, in order to further suppress periodic disturbance caused by voltage source inverter non‐linearity, an appropriate resonant controller is embedded in the RPCC. Finally, a precise test platform based on semi‐physical system AD5435 is established, and experimental results show the validity of the proposed approach.

In this paper, a five-phase permanent magnet synchronous motor (five phase PMSM) decoupled model is proposed to avoid the inaccuracy and computational complexity of conventional five phase PMSM model, which always ignores the mutual inductance between the fundamental and harmonic flux linkage. Unlike traditional inductances based five phase PMSM model, the proposed five phase PMSM decoupled model is built based on flux linkages. Moreover, to improve the accuracy of the proposed five phase PMSM decoupled model for model predictive control, a duel frame-frequency adaptive flux observer (DF-FAFO) is proposed, which can estimate both fundamental flux linkage and 3rd harmonic flux linkage online. The DF-FAFO can estimate the flux linkages accurately and minimize the unwanted harmonic ripple even if the torque is changed. The effectiveness of the proposed decoupled model and the DF-FAFO is demonstrated by simulations.

Excavators are essential equipment in construction sites, and machine guidance (MG) and machine control (MC) systems are employed in excavators to improve their earthwork performance. MG and MC systems provide the equipment operator with critical information, such as the excavation depth and slope angle required for earthwork operations, thus minimizing the assistance of a surveyor. In this study, we analyzed the performance improvement offered by MG and MC systems in earthworks compared to conventional excavation methods. We conducted performance analyses from two perspectives: productivity and accuracy. Productivity represents the quantity of earthwork in terms of time units, and accuracy reflects any deviations from the designed earthwork drawing. The analyses were conducted at a domestic trench experimental site, and the results show a highly reliable 81.12% improvement in productivity and an accuracy of ±2.1 m2 compared to traditional methods. [ABSTRACT FROM AUTHOR]

This article presents the theoretical aspects of developing a control system for the processing of frozen raw meat by cutters in automatic mode. The method for analytical calculation of the productivity rate of meat cutting by a cutter with a screw tooth provides an accuracy for which relative error does not exceed 6%. The authors show automatic process control in minced meat production using a control system computer (CSC), with the aim of building an automatic control system (ACS) for chopping raw materials frozen in the form of blocks. The task of ACS synthesis was solved: the system structure and its elements were chosen, the topology of their cause-and-effect relationships and an algorithm of control devices were developed, and their parameters were determined. The ACS’s control loop scheme for raw material cutting speed was realized, where an assembly of devices was chosen as the object of management (OM): the squirrel cage induction motor (SCIM) of the cutting mechanism drive; the frequency converter (FC) of the supply voltage, which changes the rotation speed of the SCIM (the rotation speed of the milling cutter); and the milling cutter of the chopper. The shaping filter method was used, to predict the size of the meat chips produced, to modulate the perturbation acting on the system from the load side. Based on the single-stage chopping of raw meat, an automatic line is created for producing meat products, with a minced meat quality management system based on artificial intelligence on the principle of ‘unmanned technology’.

In a high-mix low volume production environment, time to market is a key factor. However, one bottleneck lies in the often times manual parametrization of machines for new or modified designs. A truly flexible manufacturing environment therefore requires a continuous data flow from the design stages to the shop floor. This paper presents a concept for the automated parameterization of machines at a large automotive plant. It describes the interface requirements of the stakeholders involved as well as the overall system architecture. Finally, the paper presents first results of a prototype tested in serial production, spanning more than 100 machines. [ABSTRACT FROM AUTHOR]

Cascading faults of computer numerical control machine tools will lead to frequent machine faults, but an effective fault analysis and control strategy can significantly reduce the frequency of such cascading faults. The numerous studies have focused on faulty parts using established fault diagnosis models centered on faulty parts and developed measures for controlling machine tool reliability from the parts' perspective. However, the internal parts of machine tools are strongly coupled, and when one part or assembly begins operating abnormally, it can easily initiate the abnormal operation of other parts or the entire assembly, which can lead to failures. Thus, a fault diagnosis method that considers only individual faulty parts ignores the problem of fault propagation between parts, which may lead to failure to locate the root cause. To address this problem, this paper proposes a cascading fault analysis and control strategy based on meta action. First, the functional components are decomposed into meta actions using the “function-motion-action” principle. Second, the directed edges and hierarchical digraph of meta action fault propagation are obtained. Third, the PageRank algorithm is used to calculate the fault propagation impact degree of each directed edge, and the key paths of meta action fault propagation are extracted based on the hierarchical digraph and the impact degree. Finally, the fault tree analysis method is applied to analyze the meta action on key paths, and feasible machine control measures are developed. The feasibility and effectiveness of the method are demonstrated using an example machining center.

This study proposes an improved power density permanent magnet synchronous motor (PMSM) for more electric aircraft (MEA) and conducts a design study on aerospace motors. To improve the power density of PMSM, a dual permanent magnet structure using high‐temperature resistant high‐performance permanent magnets and high‐performance soft magnetic alloy material is creatively designed. Methods of lightweight structure designed in both stator and rotor meanwhile are combined as another mean to increase power density. The optimisation models for 6‐slot/8‐pole and 12‐slot/10‐pole configurations are first established based on finite element analysis. Methods of improving the power density of PMSM are then given, including minimum core back yoke thickness and lightweight structure design. The electromagnetic characteristics of the optimised machine are analysed by finite element analysis software, including back electromotive force (back‐EMF), inductance, and power loss. The configuration of 12‐slot/10‐pole is selected as the best design scheme for MEA, based on which a prototype is manufactured and tested. The experiment results of cogging torque and line back‐EMF are in good agreement with the simulation results, which shows the rationality of the designed new machine. The design proves to be effective for improving the power density of aerospace motors. [ABSTRACT FROM AUTHOR]

Compared with the conventional three‐phase motors, the dual three‐phase permanent magnet synchronous motors (PMSMs) have many advantages and have been widely used in various drive fields. However, one major disadvantage of these machines is that they are easy to generate large stator current harmonics, which makes it difficult to have an excellent performance in the drive field. To solve this problem, this study introduces a current harmonic elimination method based on a spatial analytical model of flux linkage. The study reconstructed the analytical model of flux linkage from finite element analysis. The analytical model can describe the spatial harmonics of flux linkage by considering the rotor position information. Based on the model, an active feedforward controller was proposed to eliminate current harmonics by actively injecting the corresponding voltage harmonics, the voltage harmonics are calculated by the model of flux linkage. The performance of the proposed method in eliminating current harmonics is verified by simulations and experiments. [ABSTRACT FROM AUTHOR]

High frequency (HF) sinusoidal pulsating voltage injection is a reliable method for position sensorless control in low speed range. For HF voltage injection based methods, position signal demodulation plays a key role. However, the conventional sinusoidal demodulation suffers from long settling time and limited bandwidth because of requirement of a low‐pass filter (LPF) to suppress HF harmonics in the estimated position. Additionally, the overall performance is deteriorated due to the characteristic of linear demodulation. To address these issues, the cube of q‐axis HF current instead of itself is used as the carrier of position estimation error. In this way, the input variable for phase‐locked loop (PLL) is the cube function with respect to the position deviation. During steady state, the equivalent gain in PLL is very small and thus the estimated position is non‐sensitive against high‐frequency harmonics, thereby the LPF is no longer required in the proposed method. While during dynamic process, the equivalent gain is increased leading to a fast converging rate when compared with the conventional method. The stability and dynamic performance are theoretically analysed by the magnitude–frequency diagram. The superiority of the proposed method was experimentally justified and the obtained results show that both steady‐state and dynamic performance are improved when compared with the prior art. [ABSTRACT FROM AUTHOR]

The direct torque control (DTC) of permanent magnet synchronous motor (PMSM) drives is a noticeable practice in industrial applications due to its quick dynamic performance. However, due to the presence of hysteresis controllers and inaccurate switching tables especially for the multilevel fed DTC drives are facing higher ripples in torque and flux response. An improved DTC for three‐level open‐end winding PMSM drive is proposed in this article and features reduction of flux and torque ripples. The torque and flux performances of the PMSM are directly controlled by the calculated reference voltage vector in the stationary reference frame. The voltage vector tables are proposed based on the length of the voltage space vectors and the actual voltage vector nearer to the calculated reference voltage vector is selected so that the minimum ripples exist in flux and torque responses. The steady‐state and dynamic conditions of the proposed DTC method are verified in the real‐time experiment and also compared with the conventional DTC as well as the recently developed control methods. [ABSTRACT FROM AUTHOR]

The magnetic effects and consequently the radial force are the main causes of noise in switched reluctance motors (SRMs). In this study a new design for SRM is developed in order to reduce acoustic noise. In this research a new design for SRM is developed in order to reduce the acoustic noise. In this investigation, at first, different SRM structures are simulated using JMAG software. An 8/6‐pole SRM is designed and built with special modification in the rotor and stator structures. For increasing mechanical strength, trapezoidal stator and rotor pole shape with poles arc βr = βs = 21° are proposed. In this design the taper angles of stator and rotor poles are equal. For noise reduction, the mechanical restructuring is done according to stress analysis. The new designed SRM are simulated and tested experimentally under no‐load and full‐load conditions. The results are shown and compared. Comparison between these results and the results of other structures shows that the acoustic noise of the newly designed motor is reduced considerably. The results show an acoustic noise reduction of ∼72% in new structure SRM. [ABSTRACT FROM AUTHOR]

Power converter faults represent about 12% of electrical system faults. More than 31% of these converter faults are caused by the transistors in the converters. These transistor failures are classified into open‐gate and short‐gate faults. A fault diagnostic and tolerant control system is proposed in this study for an open‐gate fault of a three‐phase voltage‐source inverter (VSI). The system under study is an induction motor fed by a VSI. The diagnostic technique uses a detection method of positive and negative sequence components, which requires only the measurement of motor currents. The diagnostic signals are derived from the negative sequence components of the motor currents. These signals are then compared using logic functions to trigger the tolerant control. In the case of an open‐gate fault, the tolerant system converts the inverter topology from six switches to four switches where the faulty inverter leg is disconnected. The proposed control method was evaluated under steady‐state and transient conditions through simulation and experiments. The results confirm an effective and reliable performance of the motor under an open‐gate fault. [ABSTRACT FROM AUTHOR]

In this study, the non‐linear deadbeat direct torque and flux control (N‐DB‐DTFC) scheme is proposed for switched reluctance motor (SRM) to achieve torque and flux precise control. For torque control part, the Fourier series form of inductance is used to establish the non‐linear torque model of SRM. As for the flux control, stator flux‐oriented is adopted to achieve the flux control and simplified calculation in N‐DB‐DTFC. In addition, the synthetic voltage vectors are applied by pulse‐width modulation. In order to assess the performance of N‐DB‐DTFC, the comparison of torque ripple is analysed among the traditional deadbeat controls in the simulation and experiment. Although, for the torque transient response, three deadbeat controls show the strong robustness and adaptability. In the results, the proposed N‐DB‐DTFC strategy shows better reflection in terms of lower torque ripple. Moreover, the results of simulation and experiment are based on a three‐phase 12/8‐poles SRM. [ABSTRACT FROM AUTHOR]

Doubly-fed induction generators (DFIGs) have drawn prominent interest in the field of wind power generation, but they are vulnerable to grid faults. Grid codes mandate DFIGs to employ a sort of fault ride-through (FRT) technique during faults. Fault current limiters (FCLs) always help to augment the FRT capability of DFIGs and a non-linear controller boosts their performances. In this study, a non-linear auto-regressive moving average-L2 (NARMA-L2) controller-based bridge-type flux coupling non-superconducting FCL (BFC-NSFCL) is proposed to enhance the FRT capability of the wind farm. The authors analysed the performance of the proposed NARMA-L2-based BFC-NSFCL (NL2-BFC-NSFCL) against that of the conventionally used series dynamic braking resistor (SDBR), bridge-type FCL (BFCL), and proportional–integral (PI) controller-based BFC-NSFCL (PI-BFC-NSFCL). They tested the performance of the NL2-BFC-NSFCL through multiple temporary and permanent fault scenarios and carried out the mathematical and graphical analysis in MATLAB/Simulink platform. They found that the proposed NL2-BFC-NSFCL's performance surpasses the performances of the SDBR, the BFCL, and the PI-BFC-NSFCL. Moreover, the NL2-BFC-NSFCL has faster system recovery capability after the occurrence of any fault than other competitors. [ABSTRACT FROM AUTHOR]

This study proposes a model predictive control (MPC) method with a fixed weighting factor for three‐phase four‐switch inverter‐fed permanent magnet synchronous motor drives to suppress the capacitor voltage offset. The prediction model of the capacitor voltage difference is obtained based on the relationship between capacitor voltage and phase current. Then by analysing the relationship between basic voltage vector, electromagnetic torque and flux amplitude, the control of electromagnetic torque and flux in the model predictive torque control is transformed into the control of the voltage vector. The dimension of the capacitor voltage difference is the same as that of the voltage vector, hence the cost function with the fixed weighting factor is defined with the consideration of the capacitor voltage offset suppression. The effectiveness of the proposed MPC method is validated by the simulation and experiment. [ABSTRACT FROM AUTHOR]