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Permanent magnet synchronous spherical motors can have wide use in robotics and industrial automation. They enable three-DOF omnidirectional motion of their rotor. They are suitable for several applications, such as actuation in robotics, traction in electric vehicles and use in several automation systems. Unlike conventional synchronous motors, permanent magnet synchronous spherical motors consist of a fixed inner shell, which is the stator, and a rotating outer shell, which is the rotor. Their dynamic model is multivariable and strongly nonlinear. The treatment of the associated control problem is important.

In this paper, the multivariable dynamic model of permanent magnet synchronous spherical motors is analysed, and a nonlinear optimal (H-infinity) control method is developed for it. Differential flatness properties are proven for the spherical motors’ state-space model. Next, the motors’ state-space description undergoes approximate linearization with the use of first-order Taylor series expansion and through the computation of the associated Jacobian matrices. The linearization process takes place at each sampling instance around a time-varying operating point, which is defined by the present value of the motors’ state vector and by the last sampled value of the control input vector. For the approximately linearized model of the permanent magnet synchronous spherical motors, a stabilizing H-infinity feedback controller is designed. To compute the controller’s gains, an algebraic Riccati equation has to be repetitively solved at each time-step of the control algorithm. The global stability properties of the control scheme are proven through Lyapunov analysis. Finally, the performance of the nonlinear optimal control method is compared against a flatness-based control approach implemented in successive loops.

Due to the nonlinear and multivariable structure of the state-space model of spherical motors, the solution of the associated nonlinear control problem is a nontrivial task. In this paper, a novel nonlinear optimal (H-infinity) control approach is proposed for the dynamic model of permanent magnet synchronous spherical motors. The method is based on approximate linearization of the motor’s state-space model with the use of first-order Taylor series expansion and the computation of the associated Jacobian matrices. Furthermore, the paper has introduced a different solution to the nonlinear control problem of the permanent magnet synchronous spherical motor, which is based on flatness-based control implemented in successive loops.

The presented control approaches do not exhibit any limitations, but on the contrary, they have specific advantages. In comparison to global linearization-based control schemes (such as Lie-algebra-based control), they do not make use of complicated changes of state variables (diffeomorphisms) and transformations of the system's state-space description. The computed control inputs are applied directly to the initial nonlinear state-space model of the permanent magnet spherical motor without the intervention of inverse transformations and thus without coming against the risk of singularities.

The motion control problem of spherical motors is nontrivial because of the complicated nonlinear and multivariable dynamics of these electric machines. So far, there have been several attempts to apply nonlinear feedback control to permanent magnet-synchronous spherical motors. However, due to the model’s complexity, few results exist about the associated nonlinear optimal control problem. The proposed nonlinear control methods for permanent magnet synchronous spherical motors make more efficient, precise and reliable the use of such motors in robotics, electric traction and several automation systems.

The treated research topic is central for robotic and industrial automation. Permanent magnet synchronous spherical motors are suitable for several applications, such as actuation in robotics, traction in electric vehicles and use in several automation systems. The solution of the control problem for the nonlinear dynamic model of permanent magnet synchronous spherical motors has many industrial applications and therefore contributes to economic growth and development.

The proposed nonlinear optimal control method is novel compared to past attempts to solve the optimal control problem for nonlinear dynamical systems. Unlike past approaches, in the new nonlinear optimal control method, linearization is performed around a temporary operating point, which is defined by the present value of the system's state vector and by the last sampled value of the control inputs vector and not at points that belong to the desirable trajectory (setpoints). Besides, the Riccati equation which is used for computing the feedback gains of the controller is new, and so is the global stability proof for this control method. Compared to nonlinear model predictive control, which is a popular approach for treating the optimal control problem in industry, the new nonlinear optimal (H-infinity) control scheme is of proven global stability, and the convergence of its iterative search for the optimum does not depend on initial conditions and trials with multiple sets of controller parameters. It is also noteworthy that the nonlinear optimal control method is applicable to a wider class of dynamical systems than approaches based on the solution of state dependent Riccati equations (SDRE). The SDRE approaches can be applied only to dynamical systems which can be transformed into the linear parameter varying form. Besides, the nonlinear optimal control method performs better than nonlinear optimal control schemes, which use approximation of the solution of the Hamilton–Jacobi–Bellman equation by Galerkin series expansions. Furthermore, the second control method proposed in this paper, which is flatness-based control in successive loops, is also novel and demonstrates substantial contribution to nonlinear control for robotics and industrial automation.

The purpose of this study is to propose an extended reliability method for an industrial motor drive by integrating the physics of failure (PoF).

Industrial motor drive systems (IMDS) are currently expected to perform beyond the desired operating conditions to meet the demand. The PoF of the subsystem affects its reliability under such harsh operating circumstances. It is crucial to estimate reliability by integrating PoF, which helps in understanding its impact and to develop a fault-tolerant design, particularly in such an integrated drive system. An integrated PoF extended reliability method for industrial drive system is proposed to address this issue. In research, the numerical failure rate of each component of industrial drive is obtained first with the help of the MIL-HDBK-217 military handbook. Furthermore, the mathematically deduced proposed approach is modeled in the GoldSim Monte Carlo reliability workbench.

From the results, for a 15% rise in integrated PoF, the reliability and availability of the entire IMDS dropped by 23%, resulting in an impact on mean time to failure (MTTF).

The integrated PoF of the motor and motor controller affects industrial drive reliability, which falls to 0.18 with the least MTTF (2.27 years); whose overall reliability of industrial drive drops to 0.06 if it is additionally integrated with communication protocol.

The study aims to show the influence of selected mechanical parameters of the rotor on the maximum speed and parameters of the electric motor.

A simplified mechanical analysis of the rotor of the electric motor was conducted, determining the safety factor of the motor. An analysis of the impact of key rotor parameters (significant from the mechanical strength perspective) on the electromagnetic parameters and the safety factor of the selected high-speed electric motor was carried out. The influence of changes in the rotor’s geometrical dimensions (centrifugal force) on the electromagnetic parameters of the electric motor was shown.

The study shows the impact of changes in selected rotor parameters on electromagnetic parameters and the safety factor of a high-speed electric motor (at its required operating point of 45,000 rpm). The dependence of the safety factor as a function of the maximum motor speed was determined for the proposed rotor modifications.

The proposed modifications can be used in larger drive systems. They have practically no impact on increasing the value of the motor’s moment of inertia (they do not degrade the dynamics of the motor’s operation).

It was proposed to use a new design coefficient which is in relation to the motor’s safety coefficient. It has been shown that a minimal modification of the motor rotor allows to increase its maximum speed by several dozen per cent (while maintaining the safety factor). It has also been shown that when operating at maximum speed within the safe range, the change in the geometrical dimensions of the rotor hardly influences the change in the value of the centrifugal force.

The purpose of this paper is to present the influence of inter-turn short circuit faults (ITSF) on electromagnetic vibration in high-voltage line-starting permanent magnet synchronous motor (HVLSPMSMS).

In this paper, the ampere–conductor wave model of HVLSPMSM after ITSF is established. Second, a mathematical model of the magnetic field after ITSF is established, and the influence law of the ITSF on the air-gap magnetic field is analyzed. Further, the mathematical expression of the electromagnetic force density is established based on the Maxwell tensor method. The impact of HVLSPMSM torque ripple frequency, radial electromagnetic force spatial–temporal distribution and rotor unbalanced magnetic tension force by ITSF is revealed. Finally, the electromagnetic–mechanical coupling model of HVLSPMSM is established, and the vibration spectra of the motor with different degrees of ITSF are solved by numerical calculation.

In this study, it is found that the 2np order flux density harmonics and (2 N + 1) p order electromagnetic forces are not generated when ITSF occurs in HVLSPMSM.

By analyzing the multi-harmonics of HVLSPMSM after ITSF, this paper provides a reliable method for troubleshooting from the perspective of vibration and torque fluctuation and rotor unbalanced electromagnetic force.

In this paper, an improved multiobjective particle swarm optimization (PSO) algorithm is proposed to optimize a three-phase, 12-slot, 19-pole, yokeless axial-field flux-switching permanent magnet (YASA-AFFSPM) motor.

Based on the structural characteristics of the YASA-AFFSPM, a mathematical model is established to calculate the main size of the YASA-AFFSPM motor. The split ratio, stator axial length, sandwiching pole angle, rotor pole angle, PM arc and number of conductors per slot are selected as optimization variables. Also, the efficiency, power factor, cogging torque and average torque are considered as the optimization objectives. The objectives are optimized by combining the improved multiobjective PSO algorithm with electromagnetic calculation.

Based on the proposed algorithm, the investigated motor is optimized. The on-load efficiency, power factor and average torque of the motor performance have increased by 0.87%, 3.13% and 10.39%, respectively. Moreover, the cogging torque and slot fill factor have undergone decreases of 8.57% and 3.34%, respectively. Finally, the effectiveness of the algorithm is verified using experiment results.

So far, no comprehensive report has been observed on the optimization of the YASA-AFFSPM motor using evolutionary algorithms and the study of the effect of the motor parameters. Therefore, in this paper, the authors decided to investigate the effect of YASA-AFFSPM motor parameters and improve motor performance with the improved PSO method.

The purpose of this paper is to take second-hand vehicles at judicial auctions in China as the primary research direction and to explore the impact of purchasing restriction policy and city size on the relationship between the appraisal price and transaction price of second-hand motor vehicles in the context of auto purchase restriction in China from a microscopic angle. It attempts to broaden the pricing ideas of judicial appraisal enterprises in providing appraisal prices of second-hand motor vehicles and to put forward suggestions for the optimization of appraisal prices and appraisal standards of judicial appraisal enterprises.

With the help of Python, this paper crawls 59,038 lines of valid data from three leading internet judicial auction platforms, namely “Ali Auction,” “China Beijing Equity Exchange” and “Gong Pai Wang,” as research samples. Besides, this paper forms a database containing judicial auction used car appraisal prices, transaction prices, motor vehicle purchase restrictions and whether the motor vehicle carries a license plate. By constructing a multiple regression model, the impact of automobile purchase restriction policy on the price of motor vehicles appraised by judicial appraisal enterprises is investigated.

With the help of the multivariate regression model, it found that under the same condition, the city where the auction took place implemented the automobile purchase restriction before the end of the auction. The court has specified that the buyer could directly obtain the license plate after the auction. The transaction price and the evaluation price ratio will be statistically larger, which proves that the license plate has an evident value in the transaction and is traded as subject matter by the residents, and consequently brings a higher premium to the price of automobile transaction in internet judicial auction. Meanwhile, the purchase restriction policy in the first-tier cities has resulted in a significant premium on automobile license plates, which is much higher than the automobile license plate premium level in non-first-tier cities under the same conditions.

Car ownership continues to rise with rapid economic development worldwide. Control the growth of car ownership, some countries and regions mainly restrict the issuance of motor vehicle license plates, which indirectly leads to vehicle license plate indicators becoming a scarce resource. National laws permit judicial auction as a means for the people's courts to settle creditors' claims in enforcement procedures of civil cases. In the judicial auction process, the People's Court introduces third-party evaluation enterprises to appraise, assess and audit the subject and obtain the appraisal price, which guides the bidding behavior of used car buyers and indirectly affects the transaction price of used cars.

As the only subject capable of assessing the value of used cars at judicial auctions, judicial appraisal enterprises have received widespread attention for their appraisal results. This paper researches this field by screening the factors affecting the ratio of motor vehicle transaction price to the appraised price. It also analyzes how the ratio of motor vehicle transaction price to appraised price is affected by motor vehicle purchase restrictions and the situation with license plates. This paper examines the existence of premiums for motor vehicle transactions with license plates, evaluates the purchase restrictions in cities with motor vehicle purchase restrictions and verifies that the premiums for motor vehicles at judicial auctions are affected by purchase restriction policies as well as the influence of city class. These studies have important implications for judicial appraisal enterprises to establish reasonable appraisal mechanisms and optimize appraisal prices. They also provide new ideas and methods for appraisal enterprises to assess the value of used vehicles at judicial auctions.

Recently, the convolutional neural network (ConvNet) has a wide application in the classification of motor imagery EEG signals. However, the low signal-to-noise electroencephalogram (EEG) signals are collected under the interference of noises. However, the conventional ConvNet model cannot directly solve this problem. This study aims to discuss the aforementioned issues.

To solve this problem, this paper adopted a novel residual shrinkage block (RSB) to construct the ConvNet model (RSBConvNet). During the feature extraction from EEG signals, the proposed RSBConvNet prevented the noise component in EEG signals, and improved the classification accuracy of motor imagery. In the construction of RSBConvNet, the author applied the soft thresholding strategy to prevent the non-related motor imagery features in EEG signals. The soft thresholding was inserted into the residual block (RB), and the suitable threshold for the current EEG signals distribution can be learned by minimizing the loss function. Therefore, during the feature extraction of motor imagery, the proposed RSBConvNet de-noised the EEG signals and improved the discriminative of classification features.

Comparative experiments and ablation studies were done on two public benchmark datasets. Compared with conventional ConvNet models, the proposed RSBConvNet model has obvious improvements in motor imagery classification accuracy and Kappa coefficient. Ablation studies have also shown the de-noised abilities of the RSBConvNet model. Moreover, different parameters and computational methods of the RSBConvNet model have been tested on the classification of motor imagery.

Based on the experimental results, the RSBConvNet constructed in this paper has an excellent recognition accuracy of MI-BCI, which can be used for further applications for the online MI-BCI.

This paper aims to propose a novel simple and efficient structure for line-start axial-flux permanent magnet (LSAFPM) synchronous motor, especially regarding the permanent magnets (PMs) demagnetization reduction.

At first, a primitive raw scheme of the new structure for the LSAFPM motor is introduced. Considering this raw scheme, the levels of irreversible demagnetization in various regions throughout the entire volume of each PM are evaluated using 3 dimensional (3D) finite elements analysis (3D FEA) in full loading condition during startup until reaching steady state. Based on the results of these analyses, the primitive structural scheme is then modified through segmenting (cutting into four pieces) each PM from where the worst irreversible demagnetization levels occurred.

As will be demonstrated by the results of 3D FEA, the proposed modified structure is not only capable of successful startup and synchronization of the motor but also it considerably reduces the PM demagnetization level. Thus, the performance of the motor is significantly improved.

The demagnetization of PMs is an important effect in PM synchronous motors, which can greatly affect motor performance. Therefore, it is necessary to be considered in the motor design processes. This effect becomes much more significant in the line-start PM motors because the usual high-magnitude startup induction current produces a strong armature-reaction magnetic field, which may cause the PMs to be irreversibly demagnetized. The approach proposed in this paper provides a structural solution to mitigate the PM demagnetization effect and thereby improve the performance of an LSAFPM motor through modifying the structure of the LSAFPM motor according to an FEA-based PM demagnetization analysis. As a considerable contribution, in this analysis, the variation of demagnetization level between different areas inside each PM is computed and is considered as a basis for proposing an appropriate structural modification to mitigate the PM demagnetization effect as much as possible.

This paper aims to analyze the evolution and interaction over time of the functions of a technological innovation system (TIS) based on the concept of an innovation motor.

It is a case study of the innovation system associated with the technology for producing cage-free pullets for laying eggs in Pelotas/Rio Grande do Sul (RS).

The motors proposed by the TIS approach evolve sequentially and are associated with cumulative causality mechanisms. The study's results identified two functionalities: analysis of the chain as a whole and coordination of the actors involved in the system. The study's results also identified the presence of inflection points at the beginning of each of the motors.

The absence of a more accurate detailing of the market motor in discussions of the evolution of the motors and functions of TIS cage free Pelotas.

Innovation Motors as a new guiding approach for participatory innovation initiatives in rural areas.

Application of the TIS approach in agribusiness and proposition of two new functions for motor analysis, in addition to including inflection points as activation triggers in the evolution between motors.

In order to reduce CO₂ emissions of new cars many hydraulic and mechanical systems like e.g.: water pump, oil pump, power steering, clime compressor have been exchanged with pure electromechanical systems, which are driven only on request. This helps to reduce fuel consumption. This trend requires of utilization of modern brushless electric motors, which are controlled from power electronic control unit – ECU. In today's car can be found between 30 to 150 electric motors. Many of them are still simple brush type with ferrite magnets. Also in this area, drift in the direction of brushless motors can bee seen, because of higher efficiency, longer lifetime, lower noise, better EMC and more controllable torque vs speed characteristic. There are different technological solutions, which can been used in the area of brushless motors in order to reduce size and cost of single component. One major factor of BLDC/AC motor is rear earth permanent magnet material used during production. A magnet material cost could be in the range from 30 percent (basis price 2010) up to 90 percent (basis price 2011) of total material motor cost, depends on actual rear earth material price level. In order to reduce magnet cost, the aim of this paper is to find the most robust motor design, which can be resistant against maximum temperature and phase current amplitude for the same magnet material properties, coercive force – Hcj. This behaviour is called demagnetization property.

Analysis was performed based on review of literature, own theoretical and practical research and experience in the area of electromechanical systems for automotive application. During motor analysis computer numerical simulation method, CAD and experiment were used.

As a result, comparison of different motors' topologies with different properties of magnet materials is presented. The worked out methodology shows very good correlation between simulations and measurements. This work can be used in order to reduce test effort and reduce cost of design.

The presented methodology reduces for new designs test effort and development cost and gives an implication of robust motor topology for demagnetization effects.

It is the first paper where demagnetization effects have been studied theoretically and in laboratory in order to find the most robust design, reduce magnet cost by reduction of dysprosium content and develop simulation procedure for analysis of demagnetizations behaviours of interior and surface permanent magnet.