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Enhancing the torsional capacity of reinforced concrete (RC) beams while maintaining reasonably economic and efficient cross-sections poses a practical challenge in the design of such elements. Thus, developing and testing economically viable reinforcing techniques for enhancing the torsional capacity of RC beams is a significant aspect. Among these techniques is the continuous spiral reinforcement system that has shown promising results in enhancing the torsional capacity of rectangular RC elements. In this study, the role of continuous rectangular spiral stirrups, as a transverse reinforcement with a controllable pitch (P) and inclination angle (θ), in enhancing the torsional behavior of rectangular solid and hollow RC beams has been investigated experimentally. The applied torque was directed to lock the spirals for all specimens. The experimental program of this investigation included testing of ten specimens of normal strength RC beams; two of which were solid with closed and spiral rectangular stirrups. While the rest of specimens were hollow specimens included one beam reinforced by closed stirrups and seven beams reinforced by rectangular spiral stirrups with different reinforcing ratios. Different variables were considered to develop a wide range of the beams’ reinforcing scenarios. This includes stirrups type (conventional closed stirrups and rectangular spiral stirrups), inclined stirrups ratio, pitch, inclination angle and finally the longitudinal reinforcement ratio. In addition, a three-dimensional finite element model using ANSYS-15.0 was developed to examine the capability of the model to capture the observed torsional behavior of the experimentally tested beams. The obtained results showed that using inclined spiral rectangular stirrups in reinforcing RC solid and hollow beams greatly enhanced the torsional capacity by about 16% and 18%, respectively compared to using the conventional closed stirrups. Moreover, the results showed that using that technique leads to higher twist- angles, more ductile failure and increased strain energy by about 27% and 16% for solid and hollow beams, respectively. Lastly, the comparison between the results obtained from numerical model and experimental results showed good agreement and thus the numerical model can be used to extend the experimental work for investigating different reinforcing schemes.

An adaptive wheel-legged shape reconfigurable mobile robot, based on a scissor-like mechanism, is proposed for an obstacle detecting and surmounting robot, moving on complex terrain. The robot can dynamically adjust its own shape, according to the environment, realizing a transformation of wheel shape into leg shape and vice versa. Each wheel-legged mechanism has one degree of freedom, which means that only the relative motion of the inner and outer discs is needed to achieve the transformation of the shape into a wheel or a leg. First, the force analysis of the conversion process of the wheel-legged mechanism is carried out, while the relationship between the driving torque and the friction factor in the non-conversion trigger stage and in the conversion trigger stage is obtained. The results showed that the shape conversion can be better realized by increasing the friction factor of the trigger point. Next, the kinematics analysis of the robot, including climbing the obstacles, stairs and gully, is carried out. The motion of the spokes tip is obtained, in order to derive the folding ratio and the surmountable obstacle height of the wheel-legged mechanism. The parameters of the wheel-legged structure are optimized, to obtain better stability and obstacle climbing ability. Finally, a dynamic simulation model is established by ADAMS, to verify the obstacle climbing performance and gait rationality of the robot, in addition to a prototype experiment. The results showed that the surmountable obstacle height of the robot is about 3.05 times the spoke radius. The robot has the stability of a traditional wheel mechanism and the obstacle surmount performance of a leg mechanism, making it more suitable for field reconnaissance and exploration missions.

Considering the innately connected neutral point in a multi-functional converter system (MFCS) fed three-phase surface-mounted permanent magnet synchronous machine (SPMSM) drive, this paper develops its fault self-tolerance towards open-phase faults (OPFs) without assisted hardware. First, the operating principle of the MFCS fed SPMSM drive is explained by building a zero-sequence model. Second, to achieve fault-tolerant operations, an unconventional current vector trajectory is proposed, aiming at maintaining the torque and average input power invariable. The shape of the proposed trajectory tends to be like a heart rather than a circle with the rise of motor speed. Moreover, d-axis and zero-sequence currents vary with the position of rotor. By considering the limits of inverter voltage and current, the post-fault output capability of the drive is explicitly analyzed. Third, a new fault-tolerant control strategy is thus proposed, in which the OPF is detected by comparing the deviation between predictive and actual currents. To track the time-varying current references, a differential flatness-based current controller is further developed. Finally, experimental results are given to verify the effectiveness.

Tire and rubber track interchangeable chassis combines the advantages of tire and rubber track, which can greatly improve the maneuverability of military construction machinery. However, there is almost no effective calculation model for the real-time static steering torque. When the relative sliding speed is greater than 0.01 m/s, the influence of friction heating can not be ignored. An improved LuGre model is established to calculate the static real-time steering torque of tire and rubber track interchangeable chassis. Firstly, the friction heating model between rubber and ground is established. Combined with the influence of temperature on the dynamic performance of rubber material, the influence of friction heating on the stiffness and friction coefficient of rubber track is analyzed, and the improved LuGre friction model is established. The steering torque of tire and rubber track interchangeable chassis is affected by rubber material properties, steering speed, pavement type, and ambient temperature. Compared with the original LuGre model, the improved LuGre model captures the change in friction torque during multiple in-situ turns due to frictional heating. The error with the experimental data is small, which verifies the effectiveness of the improved LuGre model.

Consequent pole (CP) permanent magnet (PM) machines offer scope to reduce the quantity of PM material and hence cost compared to more conventional PM machine topologies of the same rating. In this type of machine, the rotor pole arc is usually optimized to realize the largest output torque with pole shaping methods used to reduce torque ripple. However, such approaches tend to be limited by constraints imposed on the pole shapes. It is common practice to adopt similar PM and iron pole shapes, an approach which does not fully account for the different characteristics of PM and iron poles in CPPM machines, often leading to large even order harmonics in the airgap flux density. This paper proposes a shaping method with a variable rotor profile and pole arc span being established by means of optimization by a Genetic Algorithm. It is demonstrated that for a fixed quantity of PM material, different PM and iron pole shapes in combination with optimal PM and iron pole arc spans are essential for ensuring both maximum output torque and lower torque ripple when due account is taken of flux leakage. It also demonstrates that since the flux density in the region under a PM pole is governed by the magnetic potential produced by magnets while it is governed by magnetic reluctance under iron pole, different PM pole and iron pole shapes are necessary to reduce the even order harmonics in a CPPM machine and consequently to reduce torque ripple. The performances of optimized and more conventional CP machines are compared by finite element method on 12-slot/8-pole prototype motors.

This tutorial paper presents the mathematics behind the widely observed air-gap field modulation phenomena in electric machines and derives the duality between electric machines and switching converters. A bibliometric analysis of the existing research on various machine types is presented to show the historical development of electric machines from the perspective of the number of publications, showing the necessity and urgency of unifying the analysis of operating principles/torque production mechanisms before the development of the general air-gap field modulation theory in 2017. The theoretical framework and its applications are reviewed. Detailed examples of how to use the developed theory to analyze the operating principle/torque production, conduct the quantitative analysis of parameters and basic performance, and make innovations from topologies of typical electric machines, are also included for verification as well as self-study.

Magnetic gears perform the same function as mechanical gears using magnetic fields instead of interlocking teeth. A review of the design processes used in the literature demonstrates that a critical design parameter, pole pair count, is often given inadequate consideration. In addition to reviewing existing prototypes, this paper uses a parametric simulation study to analyze the impacts of pole pair counts on gear performance and illustrate how the optimal pole counts vary with gear ratio and various design parameters. This paper also introduces new ripple factors, which better correlate with torque ripple than the cogging factor used in previous papers, and illustrates why designs with non-integer gear ratios tend to have much smaller torque ripples than designs with integer gear ratios. While selecting the pole counts to minimize symmetry can reduce torque ripple, designs without any symmetry are shown to experience unbalanced magnetic forces on each rotor. Thus, it is recommended to select pole counts that result in an even number of modulators but not an integer gear ratio. This paper also reveals that, for a fixed gear ratio, a nontrivial optimum pole count minimizes the electromagnetic losses.

The paper demonstrates the potential of a hybrid Wind–PV farm as STATCOM (Static Synchronous Compensator) for damping and control of overall chaotic oscillations in a two-area power system. Kundur’s modified system associated with a hybrid Wind–PV farm is simulated in MATLAB to demonstrate the detailed performance assessment of the hybrid farm. A unique controller is deployed to regulate the AC and DC currents of the STATCOM using two PI controllers. A swarm-based hybrid metaheuristic optimizer PSO-BFOA optimally tunes and controls the PI controller parameters. The system is compensated to an optimum level of 85% and exposed to a 3-phase fault. Zero dampings are accompanied by additional disturbances of a 20% change in electric torque and the reference voltage. The disturbances are made to model the worst conditions to examine the rigorous performance of the hybrid Wind–PV​ farm in alleviating the overall chaotic oscillations. The simulation results for the performance assessment in different cases, i.e., without control, with Wind-STATCOM, with PV-STATCOM, and with the hybrid Wind–PV-STATCOM, reveal the potential of the hybrid Wind–PV Farm as STATCOM in alleviating the overall chaotic oscillations.

The magnetic gear integrated permanent magnet brushless machine (MG-IPMBM) is a kind of compact structure with high torque density and complex electromagnetic energy transfer. In order to analyze the transient characteristics of the machine, an analysis method of field circuit coupling is proposed. Both magnetic gear and permanent magnet motor are magnetized by Halbach array. Combining the analytical model of the magnetic gear magnetic field with MATLAB motor simulation module, a joint simulation model of field circuit coupling double closed-loop control system based on the Simulink-analytical method is established. The electromechanical transient response characteristics of machine under load starting, load mutation and overload self-protection are analyzed. The simulation results show that the output speed and torque of machine can accurately follow the given value, and its unique overload self-protection ability greatly improves the safety of machine operation. In addition, a prototype is made and an experimental platform is built. The experimental results show that the output torque follows quickly, the torque ripple is small, and transient performance of the machine is good.

This paper aims to investigate and reveal the torque enhancement mechanism in several emerging switched flux permanent magnet (SFPM) machines by employing a unified torque equation with an improved winding factor function. Based on a hybrid finite-element (FE)/analytical method, the torque contributions of the major air-gap field harmonics in the conventional, C-core and E-core, and consequent-pole (CP) SFPM machines are identified and quantified by taking a conventional 12-stator-slot/13-rotor-tooth (12s13r) SFPM machine as a benchmark, which shows that the dominant torque proportions are contributed by the low-order field harmonics due to the amplification effect of the gear ratio. Besides, a low-order field harmonic impeding effect is observed in the conventional and C-core SFPM structures, resulting in a compromised torque capability. Whereas, since the auxiliary teeth and stator iron bridge designs provide relatively lower magnetic reluctances for low-order harmonics, the E-core and CP structures can produce improved the low-order harmonics and higher torques than the conventional one. Finally, some experiments on a CP-SFPM machine are conducted to validate the theoretical and FE analyses.

The challenges found in geothermal well drilling have forced the industry to develop new significant cost effective, time savertechnologies to go for deeper geothermal resources beyond their traditional limits. To overcome these challenges, the new Dual String Drilling (DSD) technology which is based on penetration pathway of drilling fluid and rock cuttings during drilling a well. The principle of DSD employs drilling fluid flows through the annulus of inner and outer string pipe while cutting from the bottom of the well through inner pipe. The paper describes the novel Dual String Drilling (DSD) technology, predicting their occurrence and advantages on drilling of geothermal well. The outcome shows that with DSD approach a lot of time will be saved to circulate the kick out of the well. Additionally, the characteristic response of DSD enables to improve the hole cleaning capacity, to prevent pipe stuck, better well stability, reduction in torque and drag, to remove the dynamic equivalent circulating density gradient in geothermal wells. Moreover, the paper also depicts the system and method for dual coil tubing drilling of horizontal well which follows the same principle as DSD. The comparison of DSD with conventional drilling assesses that the DSD technology is affordable and appropriate for geothermal well drilling.

In this paper, four novel evaluation indices and corresponding hierarchical optimization strategies are proposed for a deployable solar array system considering panel flexibility and joint clearance. The deployable solar array model consists of a rigid main-body, two panels and four key mechanisms, containing torsion spring mechanism, closed cable loop mechanism, latch mechanism and attitude adjustment mechanism. Rigid and flexible components are established by Nodal Coordinate Formulation and Absolute Nodal Coordinate Formulation, respectively. The clearance joint model is described by nonlinear contact force model and amendatory Coulomb friction model. The latch time, stabilization time, maximum contact force and impulse sum of the contact force of the solar array system are selected as the four novel evaluation indices to represent the complex dynamic responses of a deployable solar array with clearance joints instead of the lock torque widely used in conventional works. To eliminate the gross errors caused by the nonlinear and nonsmooth mechanical properties, a hierarchical optimization strategy based on an adaptive simulated annealing algorithm and a nondominated sorting genetic algorithm is adopted for the solar array system with clearance joints. Results indicate that the effects of panel flexibility on the evaluation index responses and design optimization of the solar array system cannot be neglected. Besides, increasing the weight factor of the stabilization time index of the rigid system may compensate for the differences in optimal results of the rigid–flexible coupling system. That may provide some references for optimization design of deployable space mechanisms considering clearance joints.

International audience; This work proposes a new approach for the optimal energy management of a hybrid electric vehicle taking into account traffic conditions. The method is based on a bi-level decomposition. At the microscopic level, the offline part computes cost maps thanks to a stochastic optimization that considers the influence of traffic, in terms of speed/acceleration probability distributions. At the online macroscopic level, a deterministic optimization computes the ideal state of charge at the end of each road segment, using the computed cost maps. The optimal torque split can then be recovered according to the cost maps and this SoC target sequence. Since the high computational cost due to the uncertainty of traffic conditions has been managed offline, the online part should be fast enough for real-time implementation on board the vehicle. Errors due to discretization and computation in the proposed algorithm have been studied. Finally, we present numerical simulations using actual traffic data, and compare the proposed bi-level method to the best possible consumption, obtained by a deterministic optimization with full knowledge of future traffic conditions, as well as to an established solution for the energy management of a hybrid electric vehicle. The solutions show a reasonable over-consumption compared with deterministic optimization, and manageable computational times for both the offline and online part.

This article identifies the parameters of an induction machine using limited and nonintrusive observations of available input voltages, stator currents, and the rotor speed. Parameter extraction is formulated as a nonconvex estimation problem, which is then relaxed to a convex conic optimization problem. While the resulting relaxation could exhibit a satisfactory performance, there might be cases where the solution of convex relaxation fails to satisfy the dynamic equations of the machine. This is remedied through a local search approach initiated using the solution obtained from the relaxed problem. The proposed method is experimentally verified on a squirrel-cage induction machine with missing measured data. Using the measured signals as the benchmark, time-domain transients produced by the parameters estimated using the proposed method show almost 20% better match compared to time-domain transients produced by the parameters obtained via conventional testing.

Direct Torque Control (DTC) scheme introduces a robust and simple control of electrical drive. However, its shortcomings such as broad torque ripple and variable switching frequency have offered several improvements like Space Vector Modulation (SVM) strategy, multilevel inverter (MLI) topology, etc. The conventional DTC which is fed by the two-level inverter has limited voltage vector, results in some difficulties to optimize the operation, especially at low operating speed. In contrast to MLI, the abundant of voltage vector has provided various amplitudes and angles that can overcome the problem of conventional DTC. Thus, this paper introduces the selected optimal voltage vector obtained from five-level Cascaded H-Bridge (CHB) inverter that employs in DTC hysteresis-based to achieve better optimization that similar to the DTC-SVM. Initially, the research work begins with an investigation on the performance comparison between a DTC hysteresis-based between two-level inverter (conventional method) and a five-level CHB inverter (proposed method). Here, a DC generator acted as a load is employed to control the operating speed instead of the speed controller (speed controller is negligible). Hence, the DTC method is optimized by minimizing the torque ripple as well as retaining the torque control capability at constant torque region on several operating speed. The selected optimal vector from the look-up table DTC of five-level CHB inverter must be dynamically appropriate to any change of torque (increased or decreased torque). For simplicity, this paper will only discuss the experimental results for both topologies of drive system. From the experimental results, it is verified that the torque ripples by the proposed method have achieved 10% and 50% reduction at high and low operating speed respectively. It is found that the DTC hysteresis-based result simpler control method than DTC-SVM while maintaining similar output performance.

In dual-motor servo systems, several factors seriously affect the tracking performance especially in high-speed and high-accuracy situations, which include machinery flexibilities, torque disturbance, unmodeled dynamics, and motor parameter differences. Given these factors, this article investigates the command filtered backstepping synchronization control (CFBSC) method for a servo system driven by two motors synchronously. Command filters are used to deal with the virtual control signals in backstepping design process to avoid the computational burden causing by repeated derivatives, and a compensation system is applied to reduce the tracking error. Adaptive control is used to compensate the torque disturbance and unmodeled dynamics. In addition, the speed and torque synchronization control signals are designed to guarantee high synchronization performance. The stability of the dual-motor servo system is proved. And the effectiveness of the proposed controller is validated through experiments.

To investigate the effects of lift and propulsive force shares on flight performance, a compound helicopter model is derived. The model consists of a helicopter model, a wing model and a propeller model. At a low speed of 100 km/h, the Lift-to-Drag ratio (L/D) of the compound helicopter is improved when the wing provides 20.2% of the take-off weight. At high speeds, the L/D can be improved when the propeller provides the total propulsive force. Lowering the main rotor speed increases the wing lift share, however, the maximum L/D increases first and then decreases. The maximum L/D increases with decreasing the blade twist of the main rotor. Decreasing the blade twist from −16° to −8° increases the maximum L/D by 2.3%, and the wing lift share is increased from 65.0% to 74.7%. When the main rotor torque is balanced by the rudder, the maximum L/D is increased by 2.2% without changing the wing lift share. The wing should provide more lift as increasing the take-off weight, which reduces the induced power of the main rotor and increases the L/D. When increasing the take-off weight from 9500 kg to 11000 kg, the maximum L/D is increased by 6.5%, and the wing lift share is increased from 74.7% to 80.2%.

Introduction: Limited evidence has been shown on ways to optimize the mechanical design of machines in order to minimize knee loads. Objective: This study compared six computer simulated models of open kinetic knee extension exercises for patellofemoral pressure and tibiofemoral forces. Methods: A musculoskeletal model of the lower limb was developed using six different cam radius to change resistive forces. A default machine, a constant cam radius, a torque-angle model, a free-weight model and two optimized models were simulated. Optimized models reduced cam radius at target knee flexion angles to minimize knee forces. Cam radius, human force, tibiofemoral compressive and shear force, and patellofemoral pressure were compared for the six models using data from five knee flexion angles. Results: Large reductions in cam radius comparing the free-weight model to other models (73-180%) were limited to the large human force for the constant cam model to other models (9-36%). Larger human force (13 -36%) was estimated to perform knee extension using a constant cam radius compared other models without large effects in knee joint forces. Conclusion: Changes in cam design effected human without a potential impact in knee loads. Resumo Introdução: As evidências são limitadas quanto às formas de otimização do arranjo mecânico das máquinas a fim de minimizar as forças na articulação do joelho. Objetivo: O presente estudo comparou seis modelos de extensão de joelhos realizados em cadeia cinética aberta sob a pressão aplicada nas articulações patelofemoral e tibiofemoral. Métodos: Um modelo do sistema musculo-esquelético do membro inferior foi desenvolvido utilizando seis desenhos de roldana com o objetivo de alterar as forças resistivas. Uma máquina referência foi utilizada, uma com uma roldana concêntrica, um modelo baseado na relação torque-ângulo dos extensores do joelho, um modelo de peso livre e dois modelos otimizando a aplicação de cargas foram simulados. A otimização foi aplicada visando reduzir o raio da roldana excêntrica e minimizar as forças aplicadas no joelho. O raio da roldana, a força produzida pelo executante, as forças compressivas e de cisalhamento nas articulações tibiofemoral e a pressão na articulação patelofemoral foram comparadas para os seis modelos de máquina utilizando cinco ângulos de flexão do joelho. Resultados: Reduções no raio da roldana foram observadas comparando o modelo de peso livre com os demais modelos (73-180%). Maior força produzida foi observada para o modelo de roldana constante comparado aos demais modelos (9-36%). Maior força produzida foi estimada para realizar a extensão do joelho utilizando a roldana constante comparada com os demais modelos (13-36%) sem efeitos sobre as forças no joelho. Conclusão: O arranjo mecânico das máquinas alterou a força produzida pelo executante sem afetar as forças aplicadas no joelho.

The paper proposes an adoption of slope, elevation, speed and route distance preview to achieve optimal energy management of plug-in hybrid electric vehicles (PHEVs). The approach is to identify route features from historical and realtime traffic data, in which information fusion model and traffic prediction model are used to improve the information accuracy. Then, dynamic programming combined with equivalent consumption minimization strategy is used to compute an optimal solution for real-time energy management. The solution is the reference for PHEV energy management control along the route. To improve the system's ability of handling changing situation, the study further explores predictive control model in the realtime control of the energy. A simulation is performed to model PHEV under above energy control strategy with route preview. The results show that the average fuel consumption of PHEV along the previewed route with model predictive control (MPC) strategy can be reduced compared with optimal strategy and base control strategy.

To face the demand for applications in which robots have to safely interact with humans and the environment, the research community developed new types of actuators with compliant characteristics. To embody compliance into the actuator, elastic elements with fixed or variable compliance can be used. Among the variable stiffness mechanisms, a popular approach is based on the agonistic-antagonistic (A-A) layout, where two prime movers are elastically connected to the output shaft of the actuator. Notwithstanding the conceptually simple realization of the A-A layout, one limitation is that, due to the nonlinear torque/deflection characteristic of the elastic transmissions and to the limited spring elongation, the stiffness range achievable at the output shaft reduces as the external torque increases. In this work, a novel layout, based on the A-A principle, is proposed to increase the torque/stiffness capability of the actuator. To achieve this result, we combine elastic transmissions with linear and nonlinear torque/deflection characteristics. The mathematical model of the new layout and a possible implementation are analyzed. Then, the design of a novel variable stiffness actuator is presented and experimental validations are shown to compare the new device with the benchmark.

This paper presents the design and validation of a backdrivable powered knee orthosis for partial assistance of lower-limb musculature, which aims to facilitate daily activities in individuals with musculoskeletal disorders. The actuator design is guided by design principles that prioritize backdrivability, output torque, and compactness. First, we show that increasing the motor diameter while reducing the gear ratio for a fixed output torque ultimately reduces the reflected inertia (and thus backdrive torque). We also identify a tradeoff with actuator torque density that can be addressed by improving the motor’s thermal environment, motivating our design of a custom Brushless DC motor with encapsulated windings. Finally, by designing a 7:1 planetary gearset directly into the stator, the actuator has a high package factor that reduces size and weight. Benchtop tests verify that the custom actuator can produce at least 23.9 Nm peak torque and 12.78 Nm continuous torque, yet has less than 2.68 Nm backdrive torque during walking conditions. Able-bodied human subjects experiments (N=3) demonstrate reduced quadriceps activation with bilateral orthosis assistance during lifting-lowering, sit-to-stand, and stair climbing. The minimal transmission also produces negligible acoustic noise.

This paper aims to speed up the response and alleviate the computing load of model predictive control (MPC) of permanent magnet synchronous machine (PMSM). For this purpose, the Laguerre functions were extended to MPC, creating novel linear controller (LMPC) for the PMSM model. Firstly, the differences of control variables between adjacent sampling periods were regarded as a unit impulse response of a stable system, which can be approximated by a few terms of Laguerre polynomials. In this way, the difference of control variables can converge to zero quickly through parameter adjustment. Then, the current and voltage constraints in the form of Laguerre functions were applied on PMSM to improve the current response to sudden changes of speed or load. Furthermore, the torque load was applied to the state space model of PMSM to optimize the response to external load. Simulation results show that the proposed LMPC controller can effectively reduce the computing complexity that restricts the application of MPC on PMSM.

This paper presents a proposal of an interfaced wind energy conversion system (WECS) using the switched reluctance generator (SRG). Unlike conventional approaches in the literature, in this paper, a bidirectional dc-dc converter is adopted as an interface stage to achieve optimal excitation voltage at the SRG side, while a voltage source converter regulates the dc-bus voltage. The SRG works with superior performance by using optimal excitation parameters, which is characterized by high efficiency and low torque ripple. In addition, the interface stage adds a filtering behavior, mitigating the voltage ripple produced by the SRG, thus improving the power quality reflected in the grid current. A comparison of optimized SRG systems, with direct connection and with interfaced connection, is conducted. Experimental results show that the interface converter improves the performance of the SRG in WECS. Although the extra converter efficiency is approximately 88%, the overall system efficiency is only reduced up to 2.5%m due the SRG optimum parameters. Nonetheless, as advantages of the method, the mechanical torque oscillation is reduced up to 9.5% in high speeds. In addition, due to the converter filtering behavior, the grid current harmonic content is reduced by up to 6% in the comparison.

Brushless DC motors have been widely used in both industrial and non-industrial applications. Commercialization of these drives by reducing their price and increasing reliability, are among the main goals of manufacturers and researchers. These goals have been partially achieved by reducing the number of switches, current or voltage sensors, and elimination of position sensors. However, according to statistics the electrolytic capacitors are both costly and inherently have the highest potential of drive failure. In this study a new control method is proposed based on simultaneous control of speed and torque in order to eliminate the high capacity electrolytic capacitors, and use switching thin-film capacitor with low capacity in DC link instead. This reduces the torque ripples resulting from voltage fluctuations in the DC-link. The validity of the proposed method was demonstrated via simulation. A laboratory prototype of the drive was also implemented to verify the theoretical and simulation results.

In this letter, the attitude reorientation problem for over-actuated rigid spacecraft subject to multiple attitude constrained zones is studied. Considering the pointing direction deviation of sensitive equipments and constraint operating set, a robust potential function for attitude constrained zones is proposed and is further leveraged to design a high-level attitude controller, which achieves asymptotic convergence of attitude reorientation error while avoiding attitude constrained zones. Moreover, to distribute the desired control torque from high-level controller to each actuator dynamically, a finite-time adaptive control allocation is developed, resulting in an improved allocation error convergence rate when compared with existing control allocation methods. Simulation examples involving a rest-to-rest attitude maneuver are given to demonstrate the effectiveness of the proposed overall control strategy.

The Savonius rotor is one of the simple and cost-effective vertical axis drag type devices for hydropower generation. The main drawback of the Savonius hydrokinetic turbine is its low performance due to negative torque developed by returning blade profile. In this paper, the performance of modified V-shaped rotor blades with different V-angles ranging from 90° to 40°, by maintaining fixed edge length, arc radius and aspect ratio of 0.7 is investigated. The numerical analysis is carried out to estimate the optimum V-angle by maintaining 70 mm depth of water with an inlet velocity of 0.3090 m/s. The numerical study revealed that, for 80° V-angle rotor blade profile, the maximum coefficient of power was found to be 0.2279 at a tip speed ratio of 0.9. This optimum V-angle model was used for experimental analysis to study the effect of aspect ratio ranging from 0.7 to 1.75 using top, middle and bottom plates by maintaining 140 mm depth of water and inlet velocity of 0.513 m/s. The rotor blade with two endplates and one middle plate with an aspect ratio of 1.75 has shown a significant increase of performance by 86.13% at a tip speed ratio of 0.86 as compared to turbine blade with two endplates.

This letter discusses the eco-driving problem, considering both electric and conventional powertrains, and presents a pathway to solving it numerically using an indirect collocation method. Despite the low-order system dynamics, the piecewise fuel/efficiency map, gear shifting, and real-world traffic/road situations bring system discontinuities/switchings and pure state constraints into the problem formulation, which make the problem highly nonlinear and nontrivial to solve. This letter introduces smooth approximations to convert the original problem to an unconstrained (and penalized) smooth boundary-value problem. This approach eliminates the discussion of the switching structure and leads to a lightweight Newton-method-based solution procedure.

A comprehensive benchmarking study has been carried out to determine the influence of the mesh formulation and chip separation methods on the reliability and accuracy of finite element modelling of large diameter drilling operations. The Coupled Eulerian–Lagrangian and the updated-Lagrangian (with element deletion) formulations available in ABAQUS/Explicit, together with the updated-Lagrangian (with re-meshing) formulation in DEFORM 3D are compared by simulating through-coolant drilling of AISI 1045. The Johnson–Cook damage model was implemented by a sub-routine in DEFORM 3D to ensure a consistent damage model is implemented across the formulations. Experimentally measured drilling thrust force, torque, and chip thickness values were used to compare the models performance and assess the accuracy of the predictions. The updated-Lagrangian with dynamic re-meshing was found to be the best performing methodology concerning the accuracy of predictions, whilst the Coupled Eulerian–Lagrangian methodology significantly under-predicted the drilling thrust force and torque. Due to numerical instabilities and computational cost, the updated-Lagrangian with element deletion method is not recommended to model large diameter drilling.

A new hybrid magnetic source field modulation machine (HMS-FMM) is proposed in this paper, which can work in a wide speed range and guarantee high quality torque output. Due to the bidirectional flux modulation effect applied in HMS-FMM, a large number of working harmonics can be used to generate torque. Direct current excitation is employed to regulate airgap flux density at stator yoke for wide speed range and low harmonic distortion rate at flux weakening state. In order to improve the air gap flux density, the auxiliary tooth is introduced to connect ferrite and stator tooth for providing parallel magnetic circuit. The proposed topology, operating principle and key design parameters are described. Then, the electromagnetic performances are analyzed using finite element analysis (FEA) including magnetic field distribution, back electromotive force, torque characteristics and irreversible demagnetization assessment for magnets. The FEA-predicted results show that the proposed HMS-FMM is an appealing choice for electric vehicle application, which has the merit of high torque production with low torque ripple and safe operation without demagnetization risk in wide operation range.

In this article, a new torque sharing function (TSF) method is proposed for torque ripple reduction in switched reluctance machines (SRMs). The proposed TSF achieves lower current tracking error by establishing a new current reference generation strategy. The phase current reference is first derived from the torque command using offline calculations and also from the phase current response that is obtained from the dynamic model of the SRM. Then, an optimization problem is formulated to shape the current reference for the objective of minimizing the torque ripple and copper losses, while maintaining the required average output torque at the given operating speed. The dynamic simulation of the SRM model is also utilized in the optimization problem. Compared to the existing conventional and optimization-based TSFs, the proposed TSF exhibits lower current tracking error due to the consideration of the current dynamics. Better torque–speed performance with improved average torque and reduced torque ripple is also obtained, especially during commutation. Simulations and experiments under different operating conditions are carried out to verify the proposed TSF method.

This paper establishes a test bench for a free piston expander–linear generator (FPE–LG) system coupled with the drive motor (DM) to promote the application of FPE–LG on vehicle. Firstly, it discusses the operating characteristics and output performance of the FPE–LG under the simulated operation conditions of vehicle. Meanwhile, it investigates the operating characteristics of FPE–LG under different torques and expansion times. Finally, this paper analyzes the influence of different torques and expansion times on the operating frequency of FPE–LG. The experimental results show that the operating frequency of FPE–LG is related to the expansion time and torque. The power output of the DM decreases as the torque increases, the power output of the DM increases first and then decreases as the expansion time increases. Therefore, the selection of suitable expansion time under different intake pressure plays an important role in improving the power output of the DM. The maximum of the peak power output of DM is about 25.8 W, when the intake pressure is 4 bar, the expansion time is 30 ms and the torque is 0.00571 N m.

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

Recent studies in wave energy have highlighted the need for a structured innovation approach in wave energy converter (WEC) design because cost-of-energy estimates have remained high. One such innovation being investigated by the National Renewable Energy Laboratory is WEC geometry control, which uses control surfaces in combination with an oscillating surge WEC (OSWEC) to increase device availability and power generation while limiting structural costs. This study performs the first analysis of annual performance for a novel OSWEC with geometry control to understand how the geometry control affects availability, annual power generation, and structural loadings like the power-take-off (PTO) torque or surge foundation force. Device hydrodynamic coefficients are calculated using linear potential theory for six geometry configurations. A nonideal PTO system is assumed and quadratic viscous damping losses are considered. Annual performance is evaluated and compared for three U.S. wave energy sites. The WEC geometry and PTO system are controlled on a sea-state basis to optimize for power capture while remaining under limits set on motion amplitude and structural loads. Results indicate that geometry control can increase availability up to 25 days in an average year depending on design limits, increase average power generation, and significantly reduce peak structural loads.

Ribbon mixers are used in various industries for the mixing of particle matter. The discrete element method (DEM) is used to investigate the effects of the particle size and density on particle mixing in a laboratory-scale ribbon mixer. The mixer consists of a ribbon impeller with spokes and a horizontal cylindrical vessel. The particle size varies from 5 to 15 mm, and density from 417 to 2500 kg/m3. A particle-scale index is used to analyse the mixing state, and the impeller torque is used to evaluate the mixer's mechanical performance. The results show that the mixing rate generally becomes slower at a given density when the particle size is reduced with the fill-level fixed. For small particle sizes, the density effect was negligible, and the particle-size effect was described by an empirical equation, which was also extrapolated for much smaller particles. Effects of particle size and density on the impeller torque were also investigated.

In this article, an improved direct instantaneous torque control (DITC) based on adaptive terminal sliding mode control (ATSMC) is proposed to suppress torque ripple and enhance the anti-interference ability for switched reluctance motors (SRMs). The proposed speed controller used in the outer loop of DITC is based on the rate of change in load torque. The state of the system converges quickly to the equilibrium point and realizes fast output of the given torque without known disturbance upper bound. Moreover, a novel reaching law is proposed to reduce torque ripple and startup time. The stability of the adaptive terminal sliding mode motion is verified by using the Lyapunov function. The improved DITC system is implemented on a 16/10 segmented-rotor SRM. Compared with sliding mode control and terminal sliding mode control, the proposed ATSMC in the DITC system behave with better performances in aspects of the speed and torque response, antiinterference ability, robustness, and torque ripple suppression. Simulation and experimental results are given to verify the effectiveness of the improved DITC.

Topology optimization is recently employed for the design of light-weight manipulator-link that enhances energy-efficiency. However, the optimized topology at one angular-position is non-optimal for others because of dynamic loading. In this work, two approaches are proposed to synthesize ‘a single optimized topology’ that performs best for all angular-positions. The first approach is based on a weighted-density parameter, where highly sensitive elements are given high weightage to the final topology. The second approach is based on the superimposition of optimized topologies, followed by normalization and re-penalization to achieve desired volume fraction. An image-processing based techniques are also performed for reduction of stresses and geometrical complexities. 1-degree-of-freedom (DOF) manipulator-link is considered for topology optimization using an objective function as minimum compliance; deflection, stress, and torque are selected as performance values. The dynamic model is prepared considering the link-trajectory of 360° rotation. A 3-phase AC-servomotor and programmable logic controller based experimental setup are devised with online measurement of strain, torque, current, and position. The theoretical performance of the synthesized link using MATLAB code is validated through simulations (ANSYS-Workbench) and experiments. The synthesized-link through the proposed approaches shows similar deflection and 36% less stress compared to the conventional method. A reduction of 50% volume fraction minimizes joint torque by 43.6% within the permissible levels of a rigid link. The proposed method is illustrated on a 1-DOF link, which can be extended to the multi-DOF system and 3-dimensional links.

In this letter, a novel lookup table (LUT)-based direct torque control (DTC) strategy is proposed for dual-inverter fed open winding permanent magnet synchronous motor drives. Torque and flux linkage are regulated by tracking the reference voltage vector (VV) on the space VV plane according to a simplified LUT. The simplified LUT is established by dividing the space VV plane into 19 regions and each region corresponds to a basic VV. The optimal VV can be obtained by locating the corresponding region of the reference VV, which significantly decreases the complexity of LUT design and maintains the simplicity of the DTC strategy. A group of optimal switching states that minimize the transition times is selected. Meanwhile, the elimination of the hysteresis controller can further decrease the switching frequency. Experimental results show that the torque ripple, current harmonics, and switching frequency of the proposed strategy are reduced compared with the traditional DTC strategy.

In this article, a novel online optimal tracking method is proposed for permanent magnet synchronous machine drives for maximum torque per ampere (MTPA) and flux-weakening (FW) operations. The conventional model-based optimal tracking methods impose heavy computational burden, because the optimality criteria are usually used along with related boundaries to develop different optimization problems for different operation regions. Compared with the conventional methods, the proposed method reduces the mathematical complexity of the optimization problem and improves the computational efficiency in real-time implementation. Only one optimization problem is solved in both MTPA and FW regions, while the enhanced projection operations are developed to ensure the current references are within the voltage and current constraints. Magnetic saturation, phase winding resistance, nonlinearity of the inverter, and dc-link voltage variation are all taken into consideration. The feasibility of the proposed online optimal tracking method has been validated on an interior permanent magnet synchronous machine (IPMSM) test bench with an off-the-shelf motor control unit. The execution time and convergence rate of the proposed method have also been evaluated with benchmark conventional methods and presented in this article.

Pneumatically driven soft robotic grippers have been extensively studied in recent years. A majority of the grippers, especially those entirely composed of soft materials, can adapt to and handle various objects. However, there are limited studies regarding the realization of arbitrary grasping postures and twisting manipulation. Furthermore, the handling efficiency or the takt time of a handling task has not been investigated frequently. Therefore, this article proposes a circular shell gripper that consists of a rigid external shell and four soft internal air chambers. The soft chambers can be pneumatically inflated, thereby enabling it to grasp an object with a large contact area. The rigid shell allows the gripper to generate a large grasping force, while providing rigidity. This allows it to achieve arbitrary handling postures and twisting manipulations. A finite element model was constructed to simulate the chamber inflation, contact area upon grasping, lifting force, and twisting torque. An analytical model was formulated to quickly predict the lifting force and the twisting torque required to manipulate a known object. The models were validated via experimental tests on the lifting and twisting of a rigid cylinder. The experimental results indicate that the shell gripper can generate a maximum lifting force and twisting torque of 50.97 N and 0.73 Nm, respectively, with an input pressure of 10 kPa. Experimental tests on a variety of food and drink products revealed that the gripper could handle deformable, heavy, and irregularly shaped objects as well as realize arbitrary manipulation posture and twisting motion. The takt time for a pick-and-place task was found to be ∼2-5 s, using an SCARA robot; this time can be further optimized (less than 1 s) by using a parallel robot. However, the gripper was unable to handle low-profile objects, due to the downward pressing force; this was identified as a limitation of the proposed design.

Based on piezoelectric ceramics' piezoelectric effect, a new type of piezoelectric ceramic friction damper (PCFD) is designed and manufactured to provide a reliable energy dissipation device for structural response control. In the PCFD, high-strength bolts limit the deformation of piezoelectric ceramics under voltage, and the resulting reaction force changes the preload of high-strength bolts, thereby realizing real-time adjustment of friction by adjusting the positive pressure on the friction surface. The influence of friction plates with different materials on the hysteretic performance of friction damper under different tightening torque is investigated by cyclic loading test to determine the friction plate's selection in the PCFD. The hysteretic performance test is carried out to evaluate the energy dissipation capacity of PCFD with different voltages, and the experimental results are compared with the theoretical values. The finite element model of PCFD is established to analyze the stress distribution of each component of the PCFD under different voltages. Based on the semi-active control characteristics of PCFD, the Takagi-Sugeno fuzzy neural network semi-active control system for frame structure with PCFD is designed. The adaptive learning function of the adaptive network-based fuzzy inference system (ANFIS) is used to generate fuzzy rules and fuzzy neural network controller (FNNC). Finally, the semi-active control simulation of three-storey frame structure model under seismic excitation is carried out by Simulink. The experimental and numerical results show that the PCFD designed in this paper has good energy dissipation capacity, and the maximum control force increases linearly with the increase of voltage. The combination of FNNC, which is established by ANFIS, and PCFD can effectively reduce the structure response.

In this article, an optimization design method of power factor is proposed for vernier permanent magnet (VPM) machine, in which the key is to analyze and investigate the power factor from the perspective of air-gap flux harmonic modulation. To improve the design efficiency, air-gap harmonics are analyzed and serve as the crucial bridge between power factor and machine geometry. It is noted that, during the operation of the VPM machine, more attention is required for the power factor of low-speed operation area. Based on the popular new European driving cycle of the electric vehicles, three low-speed driving conditions are chosen for the optimization design. For the systematic investigation, a V-shape VPM machine is selected as an optimization example. In order to evaluate conveniently, the comprehensive power factor is defined and sensitive air-gap flux harmonics of different conditions are selected as the optimization objectives, for improving the power factor characteristics in low-speed conditions. In addition, power factor and machine performances are evaluated to validate the proposed method. Finally, the prototype machine is built and tested. Both the simulation and experimental results reveal the feasibility and effectiveness of the proposed method and investigated VPM machine.

This article presents an active ball joint mechanism (ABENICS) enhanced by interactions of spherical gears. The gear-based joint drives three rotational degrees of freedom (RDoF) without slippage. The capabilities were inspired by the unique interactions between two different innovative gears [the cross spherical gear (CS-gear) and monopole gear (MP-gear)] and the superimposition of those interactions by the CS-gear's quadrature spherical tooth structure. One MP-gear constrains two of the three RDoF of the CS-gear. The driving module which drives the MP-gear converts this “constraint” into a “drive” and drives the CS-gear with two RDoF. The CS-gear orthogonally superimposes the interactions caused by two MP-gears to achieve three RDoF driving forces. The principle was revealed by analyzing an equivalent linkage modeled on the mechanism of ABENICS. The linkage also led to the kinematics and torque equations. The theory and physical characteristics of ABENICS were verified in comprehensive and continuous positioning experiments on manufactured prototypes. The flexibility of the actuator placement was also verified in different configurations of the driving modules. The active ball joint, ABENICS can transmit high torque and reliable positioning in three RDoF without an orientation sensor, which applies to robot joints and orientation control mechanisms.

The thruster fault diagnosis problem of the satellite attitude control system is investigated in this article. This challenging problem is first changed into the binary image classification issue. A deep learning based data-driven fault diagnosis approach is then presented. It benefits from this approach that the stuck-open and the stuck-close faults of thruster are detected, diagnosed, and located online with high accuracy. The proposed method is purely data-driven and directly implemented by using raw measurement data only. It is independent of the dynamics of the thruster and the mathematical model of the satellite attitude control system. The effectiveness of the proposed approach is finally demonstrated on a satellite example.

The traditional manipulator obstacle avoidance dynamics control method ignores the acceleration constraints and speed constraints of the joint obstacle avoidance, and judges the equivalent moment of inertia inaccurately, which leads to large fluctuations in the driving torque of the manipulator motor, and high maximum driving torque and acceleration peaks. Therefore, a dynamic control method of manipulator avoiding obstacles based on space operator algebra is proposed. Using the space recursion method, according to the dynamic space operator algebra system, the manipulator dynamics model is obtained, PID parameters are adjusted, and the model is controlled by three-loop closed-loop PID control to obtain the joint torque under different obstacle avoidance states, and calculate the torque feedforward. The channel transfer function enables the moment to act on the joints of the manipulator to achieve the equivalent moment of inertia control target, to identify and finely control the moment parameters, and to plan the obstacle avoidance trajectory of the manipulator. A parallel manipulator was selected for comparison experiments. The results show that the design method reduces the motor torque ripple, the maximum driving torque, and the acceleration peak in the motion trajectory plane, so that the manipulator has better motion smoothness, reduces motor energy loss, and improves dynamic performance.

Aiming at tracking control with bounded torque inputs of the flexible-joint robot manipulators, we propose a generalized saturated adaptive controller based on backstepping control, singular perturbation decoupling and neural networks. First, by using the singular perturbation theory, the full-order rigidflexible dynamics of the robot manipulator is decoupled into a slow subsystem and a fast subsystem. Second, saturated sub-controller by backstepping method is proposed for the slow subsystem, where the projection-type parameter adaptation and a class of saturation functions are applied to make the torque inputs bounded, and a saturated neural network approximator is involved to simplify the control law and to compensate for the uncertain nonlinearity. Third, for fast subsystem, a new filtered tracking error of the elastic torque is used in the fast control law to make the boundary layer subside quickly. In addition, explicit but strict stability analysis is given for the system. Finally, comparisons indicate that the proposed controller results in a more satisfactory tracking performance with keeping the control inputs bounded within the given range all the time and superior anti-disturbance capability.

During braking with ABS (Anti-Lock Brake System), low braking initial speed causes to build-up and reduce brake pressure in longer time period due to extending application time of brake pressure and response time of solenoid valve. Also, the decision about speed and acceleration variations of wheel becomes very difficult due to weak speed signals arising from low speed. This results in lower braking torque than needed on the wheels. Therefore, effects of weak wheel speed signal become more pronounced in critical road conditions due to sudden changes in wheel speed. In this study, the effects of these problems occurring in low speed were investigated on both control and braking performance of ABS under critical road conditions. For this, ABS tests were carried out for low and high speeds on four different road types, which include slippery, wet and mu-jump tests (from wet to slippery and from slippery to wet). In this way, the results were compared to both vehicle speed and road type. The test results show that the low speed worsens braking stability, control and braking performance of ABS, regardless of road conditions. For this reason, it is proposed that ABS control algorithm must be divided in two parts as low and high speed control. (C) 2021 Karabuk University. Publishing services by Elsevier B.V.

Space manipulator with free-swinging joint failure simultaneously contains kinematic and dynamic coupling relationships, so it belongs to a new underactuated system. To allow the manipulator to carry on tasks, an effective robust underactuated control method for the space manipulator with free-swinging joint failure is studied in this paper. Considering the effect of model uncertainty and joint torque disturbance, a robust underactuated control system based on the Terminal Sliding Mode Controller (TSMC) is designed, but two drawbacks are discussed: (A) Robustness depraves with eliminating chattering. (B) Control parameters are difficult to be determined under unknown uncertainty and disturbance. To improve the TSMC, the adaptive fuzzy controller is introduced to estimate the real effect of unknown uncertainty and disturbance according to deviations of sliding mode and its reaching law. The estimated result is directly compensated into active joints torque. In simulation, the space manipulator with free-swinging joint executes tasks based on the TSMC and the Adaptive Fuzzy Terminal Sliding Mode Controller (AFTSMC) respectively. Same tasks can be finished with smaller joints torque and stronger robustness based on the AFTSMC. Therefore, AFTSMC can serve as an effective robust control method for the space manipulator with free-swinging joint failure under unknown model uncertainty and torque disturbance.

In this paper, the new closed-loop current harmonics compensation strategy is introduced in the switching-table-based direct torque control (ST-DTC) of dual three-phase permanent magnet synchronous machines (dual 3-ph PMSMs). The harmonic current distortion is the major problem of ST-DTC of multiphase machines and is typically caused by the lack of control in the auxiliary x-y subspace under the vector space decomposition model. The synthetic vectors to obtain average zero voltage in the x-y subspace can be a solution. However, this cannot compensate for current harmonics, for example, due to dead-time and backelectromotive force distortion, which are also mapped into the x-y subspace. Therefore, in this work the x-y voltage references are obtained by the closed control loop that controls x-y currents to zero. To modulate the non-zero x-y voltage reference, the new modulation approach employing voltage vector groups in x-y subspace together with the new switching table is developed and incorporated into ST-DTC. Meanwhile, the analysis of the two available sets of twelve voltage vector groups illustrates a trade-off between linear range in x-y subspace and the DC link voltage utilization rate. Finally, the effectiveness of the proposed ST-DTC strategy is verified through experiments and simulation.

In this article, an adaptive repetitive learning control (ARLC) scheme is proposed for permanent magnet synchronous motor (PMSM) servo systems with bounded nonparametric uncertainties, which are divided into two separated parts. The periodically nonparametric part is involved in an unknown desired control input, and a fully saturated repetitive learning law with a continuous switching function is developed to ensure that the estimate of the unknown desired control input is continuous and confined with a prespecified region. The nonperiodically nonparametric part is transformed into the parametric form and compensated by designing the adaptive updating laws, such that a prior knowledge on the bounds of uncertainties is not required in the controller design. With the proposed ARLC scheme, a high steady-state tracking accuracy is guaranteed, and comparative experiments are provided to demonstrate the effectiveness and superiority of the proposed method.

Accurate rotor position estimation is important to ensure the high-performance operation of position sensorless permanent magnet synchronous motor (PMSM) drives. To suppress the estimated rotor position offset error (RPOE) caused by the cross-saturation effect and other factors in high-frequency signal injection based methods, a current vector angle adaptive adjustment based online compensation method is proposed. This method can accurately detect and compensate the RPOE online only using two current vectors and has low sensitivity to the motor parameters, which improves the robustness of the system. Additionally, the two current vector angles can be adaptively adjusted according to the load conditions to improve the signal-to-noise ratio and reduce the current amplitude fluctuation during the RPOE detection process. Since neither offline measurement nor finite-element analysis is required, this method has superior adaptability and universality for applications. The effectiveness and feasibility are verified by experiments on a 2.2-kW interior PMSM drive platform.