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This paper proposed the integral-proportional-derivative (I-PD) as an extension of the conventional proportional-integral-derivative (PID) method that has been used in many brushless direct current (BLDC) applications to control the BLDC motor that can deal with desired speed (reference) changes. It has elucidated a comprehensive comparative analysis between PID, intending to delineate the most efficacious control approach based on a thorough evaluation. This paper scrutinizes four principal methods: proportional-integral (PI), integral-proportional (I-P), PID, and I-PD. Our findings indicate that in the presence of voltage spike constraints, I-P or IPD emerges as the optimum choice for both four-pole and six-pole motors. Where maximum difference (MaxDiff) is the principal consideration, PI, and I-P are identified as the most suitable methods. Conversely, when the primary objective is to minimize root mean square error (RMSE), PI proves superior for four-pole motors, while PID is preferable for six-pole types. Notably, I-P demonstrates excellent performance in terms of settling time for both motor types. In summation, I-P stands out as the preeminent choice if the objective is to select a singular method that ensures optimal performance across all parameters for a four-pole or six-pole motor. [ABSTRACT FROM AUTHOR]

With the growing demand and projected shortage of rare earth elements in the near future, the urgent task of developing energy-efficient electrical equipment with less dependence on rare earth magnets has become paramount. The use of permanent magnet-assisted synchronous reluctance motors (PMaSynRMs), which reduce the consumption of rare earth magnets, can help solve this problem. This article presents a theoretical analysis of the characteristics of PMaSynRM in a subway train drive. Options with rare earth and ferrite magnets are considered. Optimization of the motor designs considering the train movement cycle is carried out using the Nelder-Mead method. Characteristics of the motors, such as losses, torque ripple, and inverter power rating, as well as the mass and cost of active materials, are compared. [ABSTRACT FROM AUTHOR]

Energy harvesting from human motions can extend battery lifespan and enhance mobile device convenience, with promising applications in military and medical fields. Knee motion is an excellent candidate for energy harvesting due to its significant recoverable negative work. This paper aims to design an Electro-Magnetic Energy Harvester (EMEH) that captures power from knee muscle work during walking. We used 2D motion capture techniques to obtain input data, including knee angular rotation and muscle work during walking. Position vectors were extracted with a motion tracker, angular positions were formulated, and the data were imported into MATLAB® Simscape MultibodyTM to develop a walking-leg model. The model obtained angular velocity, torque, and power, revealing an angular displacement within −60-0°, a maximum angular velocity of 5.42 rad/s, a maximum torque of 30 Nm, and an average power of 15.9 W. These results indicated both positive and negative work phases in one gait cycle, consistent with reference data, helping determine the energy harvester’s operating range. The EMEH model in MATLAB/Simulink® predicted the system’s output voltage and power, guiding prototype construction. Performance tests of the prototype showed a peak power output of about 8 W, with cumulative energy harvested at 5.5 J per gait cycle. With a prototype mass of 1.35 kg, the design achieved an average power density of 3.12 W/kg. Thus, our compact and lightweight EMEH prototype successfully converted the motion of the human knee into electricity while walking, achieving a power output suitable for practical applications.

With the growing demand and projected shortage of rare earth elements in the near future, the urgent task of developing energy-efficient electrical equipment with less dependence on rare earth magnets has become paramount. The use of permanent magnet-assisted synchronous reluctance motors (PMaSynRMs), which reduce the consumption of rare earth magnets, can help solve this problem. This article presents a theoretical analysis of the characteristics of PMaSynRM in a subway train drive. Options with rare earth and ferrite magnets are considered. Optimization of the motor designs considering the train movement cycle is carried out using the Nelder-Mead method. Characteristics of the motors, such as losses, torque ripple, and inverter power rating, as well as the mass and cost of active materials, are compared.

The power tools industry has been propelled into a new era of innovation through the widespread integration of brushless motors. These sophisticated powerhouses have revolutionized the industry by delivering heightened efficiency, prolonged operational lifespans, and elevated power output, fundamentally reshaping the standards of performance. Despite these remarkable advantages, the journey toward excellence is not without its challenges. A central predicament lies in the intensified heat generation intrinsic to brushless motors, culminating in a complex phenomenon known as thermal expansion. This article embarks on an intricate exploration, shedding light on the transformative potential of real-time thermal expansion monitoring as a pivotal solution within the realm of brushless motors. [ABSTRACT FROM AUTHOR]

The power tools industry has been propelled into a new era of innovation through the widespread integration of brushless motors. These sophisticated powerhouses have revolutionized the industry by delivering heightened efficiency, prolonged operational lifespans, and elevated power output, fundamentally reshaping the standards of performance. Despite these remarkable advantages, the journey toward excellence is not without its challenges. A central predicament lies in the intensified heat generation intrinsic to brushless motors, culminating in a complex phenomenon known as thermal expansion. This article embarks on an intricate exploration, shedding light on the transformative potential of real-time thermal expansion monitoring as a pivotal solution within the realm of brushless motors.

In recent years, exterior-rotor brushless DC motors have become increasingly popular in robotics applications due to their compact shape and high torque density. However, these motors were originally used for continuous operation in drones. For applications such as exoskeletons, prostheses, or legged robots, short bursts of high power are often required. Unfortunately, vendors do not typically provide data on the motors' performance under these conditions. This paper presents experimental data on the torque–speed relationship, efficiency, and thermal responses of one of the most widely used outrunner-type brushless motors across its full operating range, including high-power short-duration operation. The results of this study can inform the selection and design of actuators for a range of robotics applications, particularly those that require high power output for brief periods of time. [ABSTRACT FROM AUTHOR]

A three-phase GaN-based motor inverter IC with three integrated phase current mirror sensors (sense-FETs or sense-HEMTs, 1200:1 ratio), a temperature sensor, and an amplifier is presented and experimentally operated. The three low-side currents are read out by virtual grounding transimpedance amplifiers. A modified summed DC current readout circuit using only one amplifier is also discussed. During continuous 24 V motor operation with space-vector pulse width modulation (SVPWM), the sensor signal is measured and a bidirectional measurement capability is verified. The measured risetime of the sensor signal is 51 ns, indicating around 7 MHz bandwidth (without intentional optimization for high bandwidth). The IC is operated up to 32 V on DC-biased semi-floating substrate to limit negative static back-gating of the high-side transistors to around −7% of the DC-link voltage. Analysis of the capacitive coupling from the three switch-nodes to the substrate is calculated for SVPWM based on capacitance measurement, resulting in four discrete semi-floating substrate voltage levels, which is experimentally verified. Integrated advanced power converter topologies with sensors improve the power density of power electronics applications, such as for low-voltage motor drive. [ABSTRACT FROM AUTHOR]

The present paper is focused on designing and manufacturing a remote-control test bench for RPA's brushless motors. The main components of the testing bench (structural, mechanical and electric components) are presented, how they are coupled, and the operating principle. The test bench is characterized by five emergency systems, one manual and four automated emergency systems that can stop the test under different conditions to avoid damaging the motor. To validate the testing bench, a SK3-5045 660 kV electric motor was selected along with a carbon fibre reinforced composite propeller. It was experimentally demonstrated that the test bench was fully automated, there were measured the propulsion force, current intensity, voltage, but also the consumed power of a motor intended for an RPA. The test results were used to determine the motorization performance and power consumption of an RPA designed with four electric motors (quadcopter type).

Motors with rare earth permanent magnets are the most compact and energy efficient in most applications. However, their use as traction motors for off-highway vehicles, such as mining dump trucks, is challenging not only because of the high cost of the magnets, but also because of the difficulty of providing a wide range of constant power speed control due to the unregulated permanent magnet flux. For this reason, induction motors remain the most popular type of motor for hybrid and all-electric mining dump trucks. However, the use of an induction motor results in increased power loss, increased current, and high temperature ripple of the power switches of the solid-state inverter when stopping on a slope with an electric brake. In this article, a theoretical comparison between an induction motor (IM) and a magnet-free wound rotor synchronous motor (WRSM) with a rotor DC-excitation in a mining dump truck drive is presented. Both motors have an identical stator outer diameter, and their geometry is optimized using the Nelder-Mead method. 2D finite element analysis in the time domain is used to calculate the IM characteristics. Steady-state characteristics of the motors such as efficiency, losses, torque ripple, required inverter power, dimensions, weight and cost of active materials are compared. In addition, losses and temperature ripples in the power modules of the semiconductor inverter, which affect the reliability of the drive, are compared when using the considered motors. The study demonstrates that the WRSM offers significant benefits such as reduced power loss, inverter power requirement, cost and mass of active materials, making it promising for use in mining trucks.

This review of the state of the art aims to collect the description and main research results in the field of development and validation of control algorithms with the main purpose to solve the problem of cogging torque and main sources of electromagnetic torque ripple. In particular, we focus on electric drives for advanced and modern mechatronic applications such as industrial automation, robotics, and automotive applications, with special emphasis on work that exploits model-based design. A great added value of this paper is to explicitly show the operational steps required for the model-based design design of optimized control algorithms for electric drives where it is necessary to make up for electromagnetic torque oscillations due to the main sources of ripple, particularly cogging torque. The ultimate goal of this paper is to provide researchers approaching this particular problem with a comprehensive collection of the most effective solutions reported in the state of the art and also a summary for effectively applying the model-based design methodology. [ABSTRACT FROM AUTHOR]

The magnetic coupling phenomenon widely exists in the type of double rotor motor, which is difficult to be eliminated completely due to the interactions between two layers of air-gap magnetic fields in a compact geometry structure. This article studies magnetic coupling in the perspective of air-gap harmonic groups, where the novelty is to propose the concept of positive coupling harmonics and the negative one. And, a double rotor flux-switching PM machine is chosen as the research subject. Then, the article begins with the analytical investigation of the modulation principle considering magnetic coupling, where the coupling harmonic group factor is defined. According to this factor, the coupling harmonics are analyzed and selected, and the positive and negative coupling harmonic groups are further determined. Next, the influence of coupling harmonic group on the machine performance is investigated in detail, including the back-EMF, torque performances, overload capability, and so on. The results show that the raise of positive coupling harmonic group factor brings the improvement of machine performances. In addition, a prototype machine is manufactured for experimental testing. Overall, theoretical analysis, simulation and test results verify the validation of the whole investigation to a large extent. [ABSTRACT FROM AUTHOR]

A detailed study was carried out on Permanent Magnet Brushless DC (PMBLDC) motor using Finite Element Method (FEM). The conceptual design of PMBLDC motor is analyzed by selecting various winding and magnetic materials, change in number of turns and altering the chemical compositions of stator material. An analytical approach has been proposed for the research carried out, especially for electrical vehicle applications. The problem and material definitions is given to the electromagnetic field simulation software named Infolytica ©/MagNet 7.1. In field solution, FEM is defined in two dimensional view. The geometrical 2D model, losses and cognitive torque is calculated for 4 pole, 350 W rated power at 1500 rpm speed motor. The analytical results with comparison for existing and proposed system are also presented clearly. The efficiency extracted from the proposed system is 96.4%.

This article proposes a novel drivetrain design of a solar-powered e-rickshaw with the controller. Hall-Effect position sensorless brushless dc (BLDC) motor drive often suffers from delayed commutation at high speed and even at low speed, conventional control does not work well due to low magnitude of back EMF. Here, the proposed sensorless control with commutation error compensation is implemented, which drives the motor over the entire range. A simple commutation error compensation algorithm is designed to detect the freewheeling pulses, reducing the control complexity for low-cost EV application and eliminating low pass filter requirement. Moreover, a zero-crossing detection (ZCD) algorithm is suggested, which inherently compensates the delay and removes the need of any additional phase compensator. A fixed delay digital filter is used to eliminate any unwanted spikes in ZCD circuit. For effective MPPT control, a modified Landsman converter is used, which provides ripple-free current at output and reduces the requirement of ripple filter at front end. The BLDC motor drive is capable of energy regeneration, which reduces the range anxiety for EV. The solar energy and the battery ensure that the vehicle never runs out of power irrespective of the climate conditions. The average distance covered by the vehicle on a single charge is improved. [ABSTRACT FROM AUTHOR]

This paper deals with the different control strategies used in the operation of Brushless motors, which generally refer to Permanent-Magnet Motors. These motors are becoming increasingly popular in industrial applications due to their high-efficiency, fast dynamic response and compact size. Until recently, programming and implementation costs of high-performance control algorithms for these motors have been prohibitive. However, great strides have been made by manufacturers such as Microchip, Freescale, IRetc to facilitate these algorithms in the architecture for their processors. This has brought down the development costs significantly and opened up whole new avenues for Brushless Motor. [ABSTRACT FROM AUTHOR]

Electrical energy is one of the energy that is needed in life. Greater attention should be paid to the use of non-renewable energy sources such as coal, natural gas and oil to generate electricity due to the limited supply of these energy sources and the environmental impact of residual waste from the production process. Therefore, another option that can be done is to use renewable energy. One example of renewable energy is solar energy whose utilization will have a more positive impact on the environment because this energy can be obtained from nature and never runs out. Environmentally friendly vehicles, both four-wheeled and two-wheeled vehicles based on hybrid and electric technology, have become one of the trends in which world transportation manufacturers are competing to develop transportation technology. The study conducted a design and numerical analysis for an electric motorcycle controller with a BLDC motor (brushless DC Motor). In this study using a BLDC motor because BLDC motors are superior to ordinary DC motors, these advantages include having higher efficiency, being durable, not using a brush, and almost not producing sound. In the experiment on June 1 at 14.00, the average solar panel voltage was 21.86 volts, the solar panel current was 1.71 Ampere, and produced 37.38 Watts of power, and from the BLDC motor rotation of 2215 Rpm. On average, BLDC motorcycles rotate bicycle tires every one hour interval from 08.00 to 17.00. In research, the best data from this study was obtained on the 6th day on June 6, 2022 with the 3 highest data, namely panel current of 1.861 volts, panel power of 35.84 amperes, and wheel rotation of 1841 Rpm. [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]

In recent years, exterior-rotor brushless DC motors have become increasingly popular in robotics applications due to their compact shape and high torque density. However, these motors were originally used for continuous operation in drones. For applications such as exoskeletons, prostheses, or legged robots, short bursts of high power are often required. Unfortunately, vendors do not typically provide data on the motors’ performance under these conditions. This paper presents experimental data on the torque–speed relationship, efficiency, and thermal responses of one of the most widely used outrunner-type brushless motors across its full operating range, including high-power short-duration operation. The results of this study can inform the selection and design of actuators for a range of robotics applications, particularly those that require high power output for brief periods of time.

The brushless doubly fed motor (BDFM) shows great potential for use in large medium-voltage adjustable-speed drive (ASD) systems due to its high reliability and cost benefits of a partially rated low-voltage power electronics converter. However, undesired performance caused by rich useless space-harmonics restricts the application of the BDFM in medium-voltage high-power ASD systems. In this article, a medium-voltage wound rotor BDFM consisting of specially designed stator and rotor windings is developed. First, the wound rotor with unequal turns and unequal pitches is designed and then compared with a nested loop counterpart. In addition, a 10 kV single-layer winding with shifted slot number in the stator is proposed to further reduce the space-harmonics by equivalent pitched effect. The finite element model of the BDFM is established to analyze electromagnetic performance and the influence of magnetic slot wedges. A lumped parameter thermal model is developed to quickly evaluate the average temperature rise of the proposed prototype. Field tests of driving a circulation water pump in a steel rolling mill were conducted to validate the feasibility of the proposed scheme. [ABSTRACT FROM AUTHOR]

The interior permanent magnet synchronous motor (IPMSM) has a structure, in which a permanent magnet is inserted inside the rotor and cogging torque is generated in its structure. To solve this problem, various methods for reducing the cogging torque are being studied. The first method is to reduce the cogging torque by increasing the air-gap length by applying tapering to the rotor or stator core. However, in case of reducing the cogging torque above a certain level, the tapering application method may cause a decrease in output because the position and shape of the permanent magnet are restricted. The second method is to apply skew to the stator or rotor. This is the most reliable way to reduce the cogging torque, but the magnetization rate of the permanent magnet is low, so the manufacturability is low. In this article, we describe a rotor with rotational tapering that fuses the advantages of tapering and skew and offsets the disadvantages. The motor design used 3-D finite element analysis (FEA), and the validity of this article was verified by making the final model and comparing it with the simulation results. [ABSTRACT FROM AUTHOR]

This article analyzed and compared the complex permeance model (CPM) and nonlinear analytical model (NAM) for surface-mounted permanent magnet (SPM) motor using a voltage source inverter (VSI). For linear CPM, the slotting effect is represented using the improved complex permeance function that describes the real slot shape rather than infinitely deep slot. NAM is extended from CPM and it replaces the magnetic potential drop of stator iron by the equivalent virtual current in the slot-opening and tooth-tip to account for the nonlinearity effect. The nonlinear inductance of SPM motor including the main phase inductance, slot leakage inductance, tooth-tip leakage inductance, and end winding leakage inductance is calculated using the frozen permeability method, which is the key to solve the electric circuit with VSI. The instantaneous back electromotive force (EMF) is calculated from the nonlinear back EMF coefficient and the back EMF neglecting iron nonlinearity. The electromagnetic torque obtained from motor model is used in the mechanical model and then the rotational speed and rotor position are obtained for the electric circuit model. Hence, the iterative solving process for the motor system is established to calculate the transient performance of SPM motor using VSI. Compared with CPM, NAM can greatly improve the calculation accuracy, which is also validated by both finite-element model and experiment. Besides, the proposed NAM is computationally efficient, which is useful for both motor design and motor control. [ABSTRACT FROM AUTHOR]

The diversity in torque-controlled actuators has enabled researchers to address numerous physical human–robot interaction applications with enhanced safety, dependability, and interaction capability. Yet, only a few torque-controlled actuators meet the challenging application requirements of mobility, improved torque/mass ratio, and structural integrability. To this end, series elastic actuators (SEAs) could meet these requirements , and they are extensively employed in state-of-the-art robot platforms –. As a result, SEA development is garnering interest in line with the growing need in related subfields in robotics. [ABSTRACT FROM AUTHOR]

This article deals with circuit modeling of power systems and more particularly of DC–AC converters used for controlling electric motors. The objective of the model is to be able to assess conducted emission currents at both inputs and outputs for fixed operating power in order to apply appropriate mitigation design rules, such as filtering. First, we propose a linear Thevenin block model of the converter considering it as a five-port linear black box allowing possible interaction between the DC and AC ports. To this extent, the block model is made of an impedance matrix and a Thevenin voltage generators vector. We also propose theoretical relationships allowing the processing of data to generate this model from measurements. Then, we test the linear simplifications on a real DC–AC converter and compare the results to measurements. For this, S-parameter measurements in off-mode and currents at the five ports in on-mode are used for the characterization of the model on a first test setup. The model is then applied and checked by comparing circuit simulated and measured current responses on a modified test setup for which the lengths of the connection cables are modified. Finally, the capability of this block model to extrapolate by calculation the response of other installation configurations is shown considering a filter and its insertion at input/output ports of the converter with much longer cables. [ABSTRACT FROM AUTHOR]

Permanent magnet (PM) motors have become great alternatives to traditional induction motors. Overhang, on either the rotor or the stator, is commonly used in PM motors. In this study, various alternatives of stator or rotor overhang in PM synchronous motors are investigated in detail. Both asymmetric and symmetric overhang cases are considered in the article. The impact of overhang on the torque quality and torque densities is investigated using 3-D finite element analysis (3D-FEA). Axial magnetic forces during assembly with and without overhang are also simulated and variation of axial force for different cases of overhangs is explored. A prototype PM motor with rotor overhang is used to validate the analyses experimentally. [ABSTRACT FROM AUTHOR]

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

In transportation vehicles, the installation of force sensors for electromechanical brake systems causes cost issues and implementation difficulties. The elimination of the sensor is highly demanded. The main vulnerability of the existing force estimators is that the algorithms either rely on shifting characteristic curves or empirical data to determine the major quantities. Hence, they are less capable of dealing with initialization offset errors, fast-changing dynamics, and uncertainties. This article presents a novel super-twisting observer to accurately estimate the clamping force on the basis of a dynamic torque-balance model. In this observer, an extended state is defined on top of a super-twisting algorithm. The observer gains are computed through a smooth Lyapunov function to guarantee the fast convergence. It is experimentally validated that the observer enhances the performance required by the antilock braking systems in comparison with conventional methods. [ABSTRACT FROM AUTHOR]

Depending on the stator lamination manufacturing processes (e.g., punching, laser cutting, clamping, welding, interlocking, and bonding), the motor’s magnetic performance parameters, such as cogging torque, hysteresis torque, and iron losses, can vary significantly. In sub-fractional horsepower (SFHP) permanent magnet motors, the manufacturing influence is typically even more severe because, due to their small dimensions, practically, the whole stator material is likely to be affected. This article analyzes the magnetic performance parameters cogging torque, hysteresis torque, and iron losses of three different stator lamination stacks (i.e., M250-35A punched with interlocking, M250-35A laser cut with bonding, and NO10 laser cut with bonding) of an SFHP single-phase brushless permanent magnet motor often found in automotive fan applications. A rheometer is used for extremely accurate torque measurements in the sub-millinewton meter range, and electron backscatter diffraction measurements are performed to visualize changes in the grain morphology and crystal orientation. The findings reveal that the punched stator with interlocking is affected the most by the manufacturing process, showing the lowest cogging torque yet the highest average hysteresis torque and thus up to 40% higher iron losses. The results presented in this article allow for both making basic stator lamination design choices and translating the iron losses, as well as the hysteresis torque and cogging torque waveforms, of a laser cut and bonded prototype into those of its punched and interlocked mass-produced counterpart. [ABSTRACT FROM AUTHOR]

In this paper, a novel control scheme for a spin-coater machine is presented, based on Passivity and Sliding Modes. The machine is used to make semiconductor thin films with a centrifugation force. A brushless direct current motor was selected as an actuator, its mathematical model is presented, including the mechanical and electrical dynamics. The control objective is the rotor speed regulation, with maximum acceleration. Taking advantage of the energy properties of the system, a sliding manifold is selected and, in order to reject the matched perturbations, the Integral Sliding Modes technique is applied. Then, with the unperturbed system, a passivity feedback is applied, to guarantee the stability around the desired equilibrium point. To complete the control scheme, an observer is included to estimate the unmeasurable estates. To prove the effectiveness of the proposed control scheme, it was implemented in a spin-coater machine and compared with a gain scheduled PID. The experimental results show a good performance of the closed-loop system, in spite of perturbations.

Synchronous homopolar motors (SHMs) have been attracting the attention of researchers for many decades. Various mathematical models of SHM have been proposed to deal with its complicated magnetic circuit. Among them, there are time-consuming 3D finite element models (FEM), equivalent circuit models neglecting some significant features of the machine design, and 2D FEM models with virtual excitation winding distorting its magnetic field picture. This paper proposes a novel 2D FEM of SHM and shows that since there are no sources of excitation in the cross-sections of the rotor and stator stacks, no virtual elements are required. This model uses the general solution of the Gauss's law for magnetism containing excitation flux. The model is based on a set of magnetostatic boundary value problems for various rotor positions. The set of boundary problems is completed with the excitation equivalent circuit. The losses in the armature and field windings and the stator and rotor magnetic cores are computed in postprocessing. All these computations are carried out for a single combination of stator and rotor stack. A symmetrization algorithm is proposed to extend the obtained results to the whole SHM. A comparison of the theoretical and experimental data for a nine-phase three-section 320 kW SHM is carried out. These SHMs were used in a mining truck with a carrying capacity of 90 tons.

In this article, three 6-slot/2-pole high-speed permanent magnet motors with 1, 2, and 3 coil-pitch windings are optimized by the finite element method taking into account stator copper loss and iron loss. Their electromagnetic performances are analyzed and compared, including air-gap flux density, back electromagnetic force, electromagnetic torque, winding inductances, and various loss components. For high-speed application, compared with 1 and 3 coil-pitch windings, the proposed 2 coil-pitch windings have a good tradeoff between winding factor and end-winding axial length which are attractive for improved torque density. Finally, the experimental results are given to validate some of the finite element predicted results. [ABSTRACT FROM AUTHOR]

This article presents a fixed-time observer-based safety control strategy for quadrotor unmanned aerial vehicles (UAVs) against multiple actuator faults and unknown disturbances. The fixed-time sliding mode observer is designed to estimate the state residual and the unknown actuator fault. Unlike most of the existing safety control strategies, the estimation time of the fault parameters is independent of initial condition, which can be strictly ensured within a fixed upper bound. Besides, the transient estimation error is regarded as a disturbance. In this article, a retrofit control mechanism with integration of the fixed-time estimator and an integral sliding mode controller is devised against multiple actuator faults and disturbances. Finally, both simulation and experimental tests demonstrate the effectiveness of the proposed UAV safety control. [ABSTRACT FROM AUTHOR]

The paper presents a study of the permanent magnet brushless DC machine, from two perspectives - from authors’ own experience in designing and manufacturing such motors, as well as from actual published research. Various constructive topologies and how they influence BLDC operation, windings used with emphasis on slot, concentrated windings, are also presented. The following part describes current techniques used for enhancing BLDC limited maximum speed, such as phase advance and dwell control, somewhat similar to flux weakening in AC permanent magnet brushless motors. The paper concludes with presentation of several methods used for sensing BLDC rotor position. Overall, the authors’ intention publishing this paper w as t o provide an insight regarding current BLDC development, as well as to assist in making documented choices when using BLDC in specific applications. [ABSTRACT FROM AUTHOR]

In this article, a variable-saliency-ratio permanent magnet motor is designed and optimized considering driving cycles. To satisfy the demands of multi-operation conditions of EVs, a variable resistance is adopted and a new variable-saliency-ratio design concept is proposed to enhance output torque, widen speed range and lower irreversible demagnetization risk effectively. A multiobjective optimization considering driving cycles is proposed, where the design objective of saliency ratio is firstly selected and optimized with multiobjective genetic algorithm method. Then, the operation performances of the motor in different operation conditions are investigated in detail. Finally, a prototype motor is built and tested. Both the simulation and experimental results verify the validity of the proposed method. [ABSTRACT FROM AUTHOR]

As aerospace applications, high reliability and low power consumption operation of the brushless direct current (BLDC) motor for the magnetically suspended control moment gyro (MSCMG) is the primary consideration. To guarantee reliability, the sensorless control without position sensors is adopted. Due to the phase lag caused by hardware and software, the commutation error is inevitable. In order to reduce losses, this article proposes a fast commutation error compensation method to improve commutation accuracy. First, the control topology of the BLDC motor with a buck converter and the commutation point detection circuit are presented. Then, the conducting back electromotive force (EMF) contained in a novel derived dc-link voltage expression is estimated through an extended state observer (ESO). Finally, the commutation error is extracted from the conducting back EMF for compensation. Different from the conventional closed-loop correction method based on the back EMF symmetry, the proposed commutation error compensation method can obtain the commutation error within only one commutation cycle by a continuous estimation with the ESO. The effectiveness of the proposed fast commutation error compensation method was evaluated with an MSCMG system. [ABSTRACT FROM AUTHOR]

Open-loop control of stepper motors reduces system cost and complexity for positioning systems. To produce a precise current waveform, a novel open-loop control implementation of a hysteresis current controller is presented and compared to the existing pulse-width modulation method. The new method extends the resolution available for a given sampling rate, allowing finer control of the motor current. Applications for precision positioning minimize external disturbances but a real, nonideal, motor introduces vibration, and nonuniform motion. Microstepping of the drive waveform approximates a continuous motion to reduce these effects but they are not fully modeled or understood. The proposed current controller is assembled with a hybrid stepper motor to verify the method experimentally. A differential evolution optimizer is applied with the complete physical system in the loop. To measure vibration, a low cost contact microphone is used, eliminating the requirement for expensive rotational sensors. This method is shown to reduce vibration across different speeds. Comparing the microstep positions of a standard sinusoidal waveform and the waveform optimized to reduce vibration, an improvement in position accuracy is also found. [ABSTRACT FROM AUTHOR]

In this article, we introduce an easy-to-implement sensorless controller specifically designed for the regulation of the propellers of unmanned aerial vehicles (UAVs). As motivation, we present a comparison of the usual motor control architectures, i.e., field-oriented control (FOC) and brushless DC (BLDC) control, with special attention to the typical back-electromotive force shapes found in this application. In particular, we show that the adoption of sensorless FOC provides several advantages, both from the efficiency and the signal quality viewpoints, provided that accurate rotor position reconstruction is available. Therefore, a recently proposed observer is integrated into a nested FOC architecture, with formal stability guarantees and low computational effort, making the resulting strategy suitable for implementation in embedded computing systems. The algorithm is then compared experimentally to a sensorless BLDC controller and a high-end commercial drive, thus validating the previous results and showing effective time-varying speed tracking, as required for precise aggressive maneuvering. These features of efficiency, accuracy, and simplicity might prove instrumental in bolstering the introduction of a novel class of high-performance, robust UAV sensorless controllers in the forthcoming years. [ABSTRACT FROM AUTHOR]

In this paper, two well-known topologies of proposed Double Sided Field Excited Linear Flux Switching Machine with Segmented Secondary (FELFSMSS) i.e. Dual Stator and Dual Mover are quantitatively compared with a valid decision of selecting Dual Stator FELFSMSS (DSFELFSMSS) based on low numerical values of detent force, thrust force ripples, and normal force, and high values of open circuit flux linkage, average thrust force, and thrust force density. In order to uplift overall thrust force profile of selected DSFELFSMSS at the rate of minimum thrust force ripple ratio, geometry based deterministic optimization and appropriate selection of AC and DC current density approach is adopted. Finally, a novel technique of auxiliary end tooth DC winding is applied to limit thrust force ripple ratio less than 10 percent.

To further enhance the safety, energy efficiency, and riding comfort of autonomous ground vehicles (AGVs), an overactuated AGV (OA-AGV) driven by four in-wheel motors and two steering motors is developed. Benefitted from the overactuation, three main advantages of the OA-AGV over conventional AGVs are demonstrated in this article. First, the lateral stability of the OA-AGV can be significantly enhanced with the additional rear wheel steering system. Second, the energy consumptions of the OA-AGV are reduced for lateral maneuvers compared with a conventional AGV with only front wheel steering. Third, the riding comfort of the OA-AGV, described by the lateral acceleration and jerk in lateral maneuvers, can also be improved. To evaluate and validate these three advantages of the OA-AGV, both simulation and experimental results are demonstrated and discussed. The conclusion is that the redundant actuators, together with sensor fusions and path planning strategies, can significantly enhance the capabilities and potentials of AGVs on safety, energy efficiency, and riding comfort. [ABSTRACT FROM AUTHOR]

Transverse flux motor (TFM) has been proven to be the ideal choice for high-torque direct drive applications, thanks to its higher specific torque density than the conventional radial flux machine. This article investigates the suitability of using TFM as the drive motor for precise position control based spacecraft applications, where mass and power reduction are the everlasting demands. Comparative configuration studies have been carried out to find the suitable type of permanent magnet motor for this application. Surface mounted TFM (SM-TFM) outweighs its competitors with lower power requirement and higher average torque, but with increased ripple content. Parametric studies of SM-TFM have been carried out to arrive at an optimal design of variables. To further increase the torque density, flux concentrated (FC) configurations of TFM have been analyzed. Average electromagnetic torque of FC and claw pole type TFM is higher than SM-TFM, with corresponding increase in the cogging torque. Electromagnetic simulation is carried out using Maxwell 3-D simulation software. Two variants of SM-TFMs are realized and the design is evaluated. Effect of Number of poles, material annealing, and strength of permanent magnet on the developed torque of SM-TFM are experimentally validated in the realized motor. [ABSTRACT FROM AUTHOR]

Brushless servomotors are widely used in industry and in all domains that require precise and easy position/speed/torque control. To further improve the performance of these motors, the segmentation of the stator core is taken into account. This approach to core construction provides a high slot fill factor, compact design, and efficient use of materials. This paper aims to present that the manufacturing constraints and tolerances of this particular core construction can increase unwanted effects in brushless motors, like cogging torque, torque ripple and their influence regarding the back-EMF. Two models for a 12slots-10 pole configuration, one with segmented core and one with standard laminated core are compared and analysed using the FEA (Finite Element Analysis) method. The influence of the additional air gaps that occur in such constructions is investigated to provide an overview for the design of segmented motors. Various lengths for air gaps between the segments of the core are taken into consideration and non-uniform distribution of such gaps. The paper also provides further steps that must be taken in order to verify/validate the studied model’s impact on motor design. [ABSTRACT FROM AUTHOR]

In electric vehicles (EVs), the major role of BLDC motor is controlling the speed of a vehicle and effective breaking. This can be achieved by reducing the torque and managing the current flow in the motor. In recent researches, current-controlling methods in BLDC give the better way in controlling the speed of a motor. This research work focuses on the design of the speed control system. In this, EV is run by the battery connected with the photovoltaic (PV) system. The proposed work optimally controls the switching devices to manage power for BLDC motor. This extracts the properties of PV system with feedback signals of the bidirectional converter and motor terminals to evaluate the energy transfer level to EV. This can also reduce the decaying effect of battery, which is connected parallel to the converter. Since the proposed controller truncates the error signal with varying angle of vector quadrant named as Truncated Angle Variant (TAV) controller, this can also monitor the accelerator frequency that refers to the required speed of the BLDC motor. The experimental result shows the performance of proposed TAV-based controlling technique and the comparison of parameters with state-of-the-art methods is also made. [ABSTRACT FROM AUTHOR]

In this article, a 48 V, 4 kW brushless fast starter (BFS) system for automotive start/stop applications is presented. The design and analysis of the machine, inverter, controller, and control algorithm are discussed in detail. The inverter and motor are integrated within the same size housing as the original brush-type starter to enable a drop-in replacement. Simulation models were used to assess the performance benefits of the brushless drive during engine autostart events and key start were compared to the conventional starting system with brush-type dc motors. To further verify the concept, a prototype BFS system was built. Both conventional 12 V brushed and proposed brushless starter were first tested on two different engine start carts. The performance in terms of autostart time, noise vibration and harshness, power consumption is compared. The proposed starter is then tested in a crossover vehicle with four-cylinder engine. Simulation and experimental results proved superior engine autostart and key start performances due to lower inertia, higher torque, and power capability of the brushless motor, especially at higher speeds. [ABSTRACT FROM AUTHOR]

Wearable robots like ankle exoskeletons have demonstrated the capability to enhance human mobility and to reduce biological efforts of human locomotion. The type of assistance provided by ankle exoskeletons could influence the lower leg muscle activities during human walking. This article aimed to systematically evaluate the lower leg muscle activities under different ankle exoskeleton assistance conditions. We measured multiple electromyography-based metrics of five lower leg muscles, while the participants walked with an ankle exoskeleton on a treadmill. Nine assistance conditions, which combined three peak times (46%, 49%, and 52% of stride time) and three peak torque levels (0.3, 0.5, and 0.7 N $\cdot$ m $\cdot$ kg $^{-1}$), are applied to assist plantarflexion during ankle push-off. Nine healthy subjects participated in the experiments. Of all investigated muscles, the activity level of l.SOL is influenced the most when exoskeleton assistance is applied. The root mean square of l.SOL activity reduces by 33.6 $\pm$ 14.0% under one assistance condition compared to walking without the exoskeleton. Our results can be used to guide studies on mechanical and control designs to improve neuromuscular interactions between exoskeletons and wearers. [ABSTRACT FROM AUTHOR]

The initial state is very important for a single-phase brushless DC (BLDC) fan motor when starting, especially in fan application with a nonstatic motor. The direction of self-rotation caused by the external thrust needs to be considered to avoid the starting fail or wrong running direction. This article proposes an initial states recognition (ISR) method to smartize the starting procedure. However, the self-rotation direction identification of single-phase BLDC motors is a challenge, which is even more difficult in some applications without rotor position sensors. The unequal air gap, which is designed by the geometric variation on the pole shoe to form the asymmetric stator, is generally the necessary design for the single-phase BLDC motor to dodge the null torque position (dead point) and determine the operation direction; and it will further form the asymmetrical waveform of the back electromotive force (EMF) voltage. The asymmetric distribution of back EMF waveform will be opposite in half cycle (positive or negative half cycle) with the rotation direction. The proposed ISR method utilizes this trait to achieve the self-rotation direction recognition before starting a dynamic single-phase BLDC fan motor. Finally, under the architecture of Hall-sensor-less control, the experimental results prove that the proposed method is reliable and feasible. [ABSTRACT FROM AUTHOR]

This article proposes a design method for a high-speed response motor system consisting of a motor and load. Various methods have been studied to improve the speed response of the motor system, but the main focus was previously advanced control techniques. However, the dynamic response of the controller can be further improved with the high-speed response motor system. The proposed method improves the speed response by increasing the bandwidth of the motor system, which is the plant of the servo system. Thus, the relationship between the bandwidth, which is an indicator of speed response and the motor system, is investigated. The motor system consists of the electrical and mechanical parameters. As both electrical and mechanical parameters affect the speed response and bandwidth of the motor system, the correlation of the time constants and bandwidth is analyzed. Based on the analyzed results, the process of designing a motor system with maximized bandwidth is introduced. An experimental based friction model is proposed to estimate the accurate speed responses and required torque of the motor system. Therefore, a motor system with maximized bandwidth is designed using the proposed design process and friction model. Finally, the rated power and speed response of the motor system are verified through simulations and experiments. [ABSTRACT FROM AUTHOR]

Nondestructive THz imaging technology is a promising technology in several industrial applications such as process monitoring and quality control. To further popularize the application of this technique in the industry, we developed photonics-based devices such as a dual-mode laser, uni-travelling carrier photodiode, and Schottky-barrier diode that enable the realization of a compact, low-cost, multifunctional continuous wave (CW) THz system. To develop CW THz reflective imaging systems with these devices, a telecentric f-θ lens and novel two-dimensional (2D) beam scanner were developed. A high-speed, low-cost 2D reflector with a 4-sided polygon mirror, a brushless DC (BLDC) motor rotating at approximately 2,990 revolutions per minute (RPM) and a stepping motor was designed to ensure that a THz image sized 500 × 400 pixels could be scanned in approximately 2 s. However, it is difficult to maintain a constant speed in high-speed rotating BLDC motors. The measured maximum deviation is approximately 0.7%, which results in distorted images. To compensate for this distortion, a sync signal reflector was designed to monitor the real-time RPM of the BLDC motor. Using the novel 2D beam scanner and sync signal reflector, the distorted images could be corrected simply, enabling the development of a 2D THz reflective imaging system using a single emitter and detector; this system could exhibit a higher speed and was more cost effective than the existing system. Although further improvements to photonics-based THz technologies are necessary, we believe that these efforts will begin an era of THz technologies as a widely used industrial technique. [ABSTRACT FROM AUTHOR]