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Researchers have recently attached more attention on permanent magnet brushless AC motors for electrified propulsion. Considering the further improvement of torque density, this paper proposes a novel pulse width modulation (PWM) magnet array and quantitatively analyzes the magnetic field with different magnet configurations. It is a good potential for reducing the magnet volume. Based on a slotless motor design which eliminates the influence of additional harmonic sources except for that from magnets, investigations on motor performance with proposed magnet array are made. Also, the improvement of torque density is discussed and verified.

This paper is to present an unmanned aerial vehicle (UAV)-oriented wireless power transfer (WPT) system which accommodates with an energy-efficient receiver. Actually, the key is to use a buck converter to greatly reduce the current through the receiving coil and the rectifying diodes. As a result, the total power loss on the receiver is effectively reduced. First, to realize the proposed design, the whole system is modeled to analyze its system-level performance. Then, the loss on the receiver is modeled to instruct the parameter design of the buck converter, namely the duty ratio and switching frequency. After that, an experimental prototype is developed to validate the effectiveness of the proposed system. Results show that the proposed WPT system can achieve a dc-to-load efficiency of 82%, which is 9% higher than the case without the buck. Moreover, when the charging current is 6 A, the total loss on the receiver is reduced up to 14.4 W by properly configuring the buck converter.

Subjective cognitive decline (SCD) is the preclinical stage of Alzheimer's disease (AD). Abnormal brain glucose metabolism and Aβ depositions can be observed in SCD subjects. Nevertheless, there was not cognitive impaired performance in standardized neuropsychological in these subjects. Cognitive reserve (CR) could be the reason to explain this phenomenon. However, correspondence between CR and SCD was still uncleared. In this study, we attained 74 subjects underwent 18FFDG PET scans (SCD1 group) and 38 patients underwent 18FAV45 PET scans (SCD2 group) from Xuanwu Hospital, Beijing, China. First, SCD1 group was divided into SCD1H (high CR, n=33, educational years>12) and SCD1L (low CR, n=41, educational years 12) and SCD2L (low CR, n=21, educational years

Human behavior recognition is a hot issue in the field of computer artificial intelligence recognition. However, most of the algorithms currently use only RGB or deep video sequences, and they are rarely combined for behavioral artificial intelligence recognition. Therefore, the algorithm relies on the firefly optimization algorithm. The two algorithms of robust depth map and RGB image are effectively combined. The SVM classifiers with multiple different kernel functions are used to evaluate them on the DHA dataset. The experimental results show that the performance of the proposed behavior description algorithm is better than some The performance of representative algorithms is better. At the same time, the performance of the algorithm is further improved after the fusion of depth data and RGB images, and it has better distinguishability and robustness.

To improve the efficiency of the tidal energy conversion system, high power density and high efficiency direct-drive permanent magnet synchronous generators are required. Therefore, this paper combines the magnetic-gearing effect with the generator and proposes a novel six-phase vernier generator topology. First, the topology is introduced and the operation principle is described. Second, the paper focuses on the induced voltage optimization by different methods, including parametric optimization, response surface method, and harmonic winding suppression. Also, the induced voltage performance is validated by FEM. Finally, the optimal design is proposed and the conclusions are drawn upon.

Outer loop PI controllers have been widely applied before the inner model predictive torque control (MPTC) to determine the torque reference, which could increase the number of tuning parameters for the total control scheme. In this paper, to simplify the structure of total control scheme and improve the performance of MPTC in dual three-phase permanent-magnet synchronous motor (DTP-PMSM), the conventional PI controller is replaced by a nonlinear function to determine the output torque reference, which has only one adjustable parameter. Then, the additional offset is necessary to compensate the speed residual error. Furthermore, a torque load observer is designed to observe the torque and determine the value of offset. Finally, the simulation is given, which demonstrates the effectiveness of the proposed method.

This paper presents a new selectable regional charging wireless power transfer (SRC-WPT) system, which can charge multiple receivers simultaneously. Meanwhile, they are put on the charging area of the system. This SRC-WPT system employs a transmitter array for WPT, which rows are controlled by relays. Furthermore, the transmitters in each row have different frequency characteristics, which can be used as the natural switches. Thus, this SRC-WPT system can selectively activate the charging region for the receivers through the different frequencies and relays. Besides, when compared with the existing multi-to-multi WPT designs, the proposed control method of the SRC-WPT system is much more simple and reliable. Finally, a model is built to verify the performances of the proposed system and the corresponding control method.

This paper proposes a novel wireless power transfer system, which can deliver three different resonant frequencies to four receivers with only two transmitting coils. It uses a three-phase high frequency inverter and two transmitting coils to deliver power to different loads with different resonant frequencies. It can realize four operating modes, including three independent resonant frequencies transmission and concurrent double frequency transmission. All these four modes are analyzed in detail. In addition, a prototype is built to verify the proposed system experimentally.

With increasing penetration of distributed renewable energy, microgrids emerge to protect the main grid from the risk caused by the intermittence of distributed renewable generation. Also, the controllable loads in microgrid provide an opportunity for operators to schedule more efficiently and economically. So, this paper proposes a price-based hour-ahead demand response program to maximize the benefit of all the suppliers and consumers in a microgrid with wind power generation. The electricity prices are designed by the convex optimization algorithm, namely the PCPM method. This distributed algorithm only requires the local information and neighboring communication, which protects the privacy of participants and promotes the marketization of microgrid. In optimization process, the power flow constraints and power loss minimization are also considered. Finally, the demonstration cases are given to validate the effectiveness of the proposed demand response program.

Electrification of the propulsion motor for electric aircraft has become an emerging research hotspot recently. In fact, the direct-drive system on the electric aircraft is to coaxially connect the motor with the propeller to produce the thrust or lift force. Also, aircraft propulsion requires high speed, high power density, high efficiency and ultra-light weight for direct drive motors. This paper focuses on the slotless and coreless stator topologies to achieve smooth propulsion. First, the machine models are proposed and compared, with explanations of unique designs. Then, since the slotless windings are very different with slotted stator windings, the winding analysis is carried out, including the arrangement, flux linkage and induced voltage. Furthermore, the no-load and rated load performances for the proposed machines are implemented by FEA tools. Finally, comparison results are used to validate the superiority of the proposed machines.

This paper aims to suppress the resonant frequency drifting of the transmitter of the one-to-multiple wireless power transfer (OWPT) system, which is caused by the reflected impedances of the unselected receivers. To overcome the frequency drifting of the transmitter and realize the full resonant of the whole circuit, it is necessary to dynamically change the compensation capacitor with tuning the circuit of the transmitter. However, with more receivers, the range of capacitance of the compensation capacitor increases. So, it leads to the increasing of the difficulty in making the capacitor array. In this paper, to cancel the unexpected frequency drifting and narrow the range of the compensation capacitor, as well as to decrease the size of the capacitor array of the transmitter, the using of hybrid compensation topology in receivers is proposed. First, based on the existing OWPT system, the hybrid compensation topology is proposed and analyzed in details. Then, the guidelines for parameters design of the transmitter is presented and analyzed in details. Finally, the simulation results are given to validate the proposed method.

This paper presents a harmonic modeling for two types of magnetic gears (MGs) by considering the nonlinear B-H curve for soft magnetic material. A convolution matrix of permeability is introduced to obtain the relation between the magnetic flux density and magnetic field strength. Subsequently, the magnetic field distribution and electromagnetic performance of MG can be calculated by solving the matrix equations in MATLAB. Then, the finite element analysis (FEA) is introduced to verify the accuracy of the proposed method. And a good agreement can be observed. Finally, based on the MG models, a PI control is simulated to evaluate the dynamic performances of MGs when used in the servo system.

Multiphase machines are welcomed for many special occasions due to their distinct merits of high torque density, high power density, high efficiency, high reliability and low torque pulsation. This work is to present an outer-rotor nine-phase dual-PM vernier (DPMV) machine with PMs on both stator and rotor sides, which can provide the high torque density and low torque pulsation. First, the machine topology and operation principle are presented and analyzed. Then, the operation performance of the machine is simulated by the finite-element method (FEM). The demonstration results shows the effectiveness and validity of the proposed machine design.

Control strategies for dual three-phase permanent magnet synchronous motors (PMSMs) mostly focus on the reduction of harmonic currents and torque ripple. But the investigation on the control approach on the dual three-phase PMSM in high-speed region has not been well discussed before. This paper aims to present a new flux weakening control scheme for a dual three-phase PMSM. Actually, the control scheme is expanded from the traditional three-phase PMSM counterparts. First, the limitation of voltage and current in dual three phase PMSMs is discussed. Then, a flux weakening control scheme is designed, which is to utilize the limited cycle to improve the high speed performance of dual three-phase PMSM. Finally, this control scheme is verified through the demonstration. The result proves the feasibility of the proposed method.

This paper proposes a complementary-structure-stator flux-modulated permanent magnet (CSS-FMPM) machine. With the complementary-stator structure, the flux line distributes more evenly and the effective space for the flux line is broaden. It extensively improves the torque performance of the machine. In addition, another two contrast DS-FMPM machines are employed and discussed, which accommodates the same inner and outer stators. After the torque optimization, the average torque of the proposed machine is up to 46.4 Nm, possessing 66% and 129% higher than the contrast two machines, respectively. Also, the torque ripple of the proposed machine is only 3.6%, while those contrast machines are 6.2% and 5.0%. Finally, the demonstration results verify the feasibility of the proposed machine design.

The paper proposes the DC-bias operation of a new double-stator hybrid flux switching permanent magnet (DSH-FSPM) machine. Firstly, by directly injecting the DC current into the armature windings, the DC-bias strategy contributes both the flux enhancing (FE) and flux weakening (FW) capabilities to the machine design. Under the FE operating mode, compared with the pure-armature-slot-winding and pure-DC-slot-winding conditions, the DC-bias operation increases the average steady torque by 41.3% and 65.5%, respectively. Under the FW operating mode, the rotational speed can be greatly expanded from the rated 500 r/min to 1865 r/min. Besides, with the integration of the double-stator structure and FSPM topology, the proposed machine combines the benefits of high power density, high efficiency, and flexible controllability.

This paper presents a sensitive and high cost-effective dual-parameter measurement technique, which is capable of measuring current and temperature based on Johnson noise thermometry (JNT) with the single tunneling magnetoresistive (TMR) sensor. The key is to utilize a TMR sensor with high sensitivity of 250 mV/V/mT to measure the current as well as temperature. Also, an ultra-low noise preamplifier with the equivalent noise as 3.1 nV/√Hz (@ 1 kHz) and a precise 10 µA constant current source are designed to implement the JNT and current measurement. Furthermore, a high-speed FPGA combined with ADC modules is used to carry out the signal processing algorithm and finally to calculate out the parameters of current and temperature. Finally, the dual-parameter sensing is verified by measuring current in the range of ±10 A and temperature ranging from −40 °C to 160 °C, respectively.

This paper presents a method to measure the velocity of permanent magnet synchronous motors (PMSMs) by sensing the external stray magnetic field (SMF) outside the stator surface. First, a magnetic circuit model of PMSM was developed to analyze the distribution of SMF. The key is to sense the SMF by a magnetic sensor and extract the frequency through a zero-crossing comparison to obtain the velocity. Then, the proposed method was validated by the finite-element-method (FEM). Moreover, a 5.5 kW three-phase PMSM testbed was built up for experimental verification. A triaxial tunneling magnetoresistive (TMR) sensor was utilized to sense the SMF in the testbed. The experimental results demonstrate that the measurement accuracy is less than ±0.15% in the range from 100 rpm to 1000 rpm. Thus, it verifies the proposed methodology can provide a cost-effective and high-accuracy alternative to the velocity measurement for PMSMs.

This paper presents a study on design parameters of a permanent magnet vernier motor (PMVM), to discuss their influences independently for motor performance improvement, where the electromagnetic torque and torque ripple are mainly taken into consideration. Basic model of the PMVM is designed with dual-stator, axial-flux topology, spoke-type magnets array, which has the feature of high torque density and relative high power factor at low speed for the direct-drive systems. Compared to a radial-flux motor, the axial-flux motor has non-equal radii in inner side and outer side, which results in extra design considerations in terms of stator slot shape, rotor core shape, and asymmetric overhang lengths. Therefore, the design parameters of slot shape, winding method, rotor core, and rotor overhang length are discussed based on the basic model of axial-flux PMVM under the constraint of motor volume. Motor characteristics are illustrated and analyzed using three dimensional finite element method (3D FEM). Finally, one prototype of optimal designed model is manufactured and tested to verify the improved motor characteristics.

This paper is to present an effective wireless power transfer (WPT) system to recharge the battery of electric unmanned aerial vehicle (e-UAV). The proposed system can generate an approximately even magnetic field which allows the e-UAV to get enough energy at different points above the charging pad. Also, based on the design, the proposed system is capable to transmit enough power at a high efficiency. Both simulation and experimentation are carried out to prove the validity of the proposed WPT system for e-UAV charging.

This paper proposes an improved model predictive torque control (MPTC) method for an open-end winding permanent magnet synchronous motor (OEW-PMSM) with reduced computation time. First, a basic predictive torque control algorithm is derived, which is based on the discrete system model and cost function. Then, a direct torque control (DTC) based switching table is developed to reduce the computation time. In addition, a weighting factor elimination method is adopted to avoid the tuning work, which is based on the equivalent reference vector of the reactive torque. Also, the optimal switching state selection strategy based on the principle of least switching losses is introduced. Simulation results are offered to verify the proposed method.

Direct-drive robotics is quite attractive because of its high efficiency, high robustness and wide application prospect. This paper is to propose a new double-stator hybrid flux switching permanent magnet (DSH-FSPM) machine for the direct-drive robotic applications. The key is to integrate the distinct merits of high torque density, flux-modulation capability, high fault-tolerant capacity and low torque ripple together. First, the machine design and flux switching principle are analyzed to illuminate the basic operation principle. Also the machine performance shows that the inner and outer torque ripples offset with each other and contribute to the low torque ripple less than 7%. Furthermore, with the addition of the DC current, the machine flux and EMF can be weakened, which can enlarge the flexibility and stability for the machine operation. The performances of the machine verify the feasibility of the new topology for the direct-drive robotics.

With the electric vehicle (EV) market growing fast, the emerging wireless EV charging technology has attracted more and more attention in recent years. As a key part of wireless charging system for EVs, the coil design is indispensable for improving the system performance. This paper presents an overview of coil designs for wireless charging of EVs, which addresses their basic structures, operating principles, and distinct features. The basic topologies including the circular rectangular pad (CRP), circular pad (CP), homogeneous pad (HP), double-D pad (DDP), double-D quadrature pad (DdQp), and bipolar pad (BP), are introduced and discussed. Also, the corresponding advantages and limitations of each topology are analyzed and discussed. Besides, some key issues of practical design problems are compared in the coil topologies. Finally, the human exposure issues are revealed.

In the present, unmanned aerial vehicles (UAV) has arisen more and more attention due to the high efficiency, ease and safety in completing complex missions [1][2].

Recently, wireless power transmission technologies have been demonstrated that they have wide applications, such as micro medical robotics and electric vehicles [1] – [5].

This paper presents three configurations of direct- drive stator permanent magnet generators (SPMGs) as potential candidates for electric power generation. The design principles are discussed with details, while the proposed configurations are analysed by using the finite element method (FEM). In particular, the no-load electromotive forces (EMFs), the steady torques, the cogging torques, the flux densities and the output powers can be analysed thoroughly. Consequently, the quantitative comparisons are concluded among three proposed generators.

This paper proposes a temperature measurement method using a giant magnetoresistive sensor as a sensing resistor based on Johnson noise thermometry. Experiments were performed to verify this approach. The results demonstrate the reliability of this approach with error less than 2.3% in the temperature range from 303 K to 423 K, which can enable a multifunctional spintronic sensor detecting temperature and magnetic field.

In this work, a novel graphene oxide (GO)/Poly(ethyleneimine) (PEI) layered film was prepared on the quartz crystal microbalance (QCM) by feasible spray process for the humidity detection. The morphology of sensitive film was analyzed by field emission scanning electron microscopy (FESEM). it was worth mentioning that a chemical bonding could be formed at the interface between PEI and GO sheets due to the acylation reaction, which was proved by the Fourier transform infrared (FTIR) transmission spectrum characterization. The humidity-sensing results showed that the frequency shift of sensors exhibited the excellent response and reproducibility, which might be partly ascribed to the effective interaction between PEI and GO. Meanwhile, an instant recovery time (5s) and negligible humidity hysteresis (less than 1%RH) were achieved. Furthermore, the mechanism of performance enhancement of layered film sensors was analyzed.

This paper presents a quantitative comparison of three topologies of double-sided long-stator type permanent magnet linear machines (PMLMs) as possible candidates for the ropeless elevator propulsion system. First, the parameters of each PMLM topology are designed using the same criteria. Then the finite element method (FEM) is employed to evaluate the performance of each topology. Specifically, the translator mass, propulsion forces, detent forces, and no-load EMFs are analyzed and compared. The quantitative comparison results show that the Halbach array PMLM configuration is preferable for the ropeless elevator application because of its small detent force as well as low total mass.

In this paper, a new hybrid-excited flux-switching (HEFS) machine is proposed with the outer-rotor configuration, which possesses the distinct feature of fault-tolerant operation. Comparing with the conventional permanent-magnet (PM) machine, it combines merits of flux control, high mechanical integrity, and low-cost. Furthermore, its fault-tolerant feature ensures its continuous operation in the event of winding faults. Hence, a new 12/10-pole HEFS machine is designed and implemented in this paper. By using time-stepping finite element method, open circuit (OC) fault and short circuit (SC) faults on the armature winding are investigated in the proposed machine for the fault-tolerant operation. The phase-current reconfiguration and flux control are applied for the remediation of the OC fault, while the SC faults is remedied by the phase-current reconfiguration merely. Both approaches demonstrate their good performances for the fault-tolerant operation.

The proposed fault-tolerant flux-reversal doubly-salient (FT-FRDS) magnetless motor drive consists of armature winding for driving and DC-field winding for field excitation. The purpose of this paper is to investigate two remedial strategies for fault-tolerant operations of the proposed motor drive under short-circuit faults. First, short-circuit phase can be disabled and the short-circuit fault can then be regarded as the open-circuit fault. By reconstructing the healthy armature phases, the reduced torque can be remedied and this is known as the fault-tolerant brushless AC (FT-BLAC) operations. Second, short-circuit fault can also be remedied based on the DC-field regulation alone, and this is known as the fault-tolerant DC-field (FT-DC) operation. These two remedial operations are compared and verified by the finite-element-method (FEM).

Reduced graphene oxide/titanium dioxide (rGO/TiO2) layered film was firstly utilized through simple spray method for trace detection of formaldehyde (HCHO) at room temperature. A remarkable sensitivity of layered film (0.8 ppm−1) was identified in the concentration range of 0.1 ppm to 0.5 ppm, which was higher than that of rGO-based sensor (0.5 ppm−1). It was worth noting that an interesting abruption behavior of rGO sheets during the thermal reduction process was observed. However, the collapse of rGO honeycomb network during temperature-rise period could be prevented due to the introduction of TiO2 nanoparticles. Furthermore, a novel mechanism based on aie combination of catalytic reactions and supporting function of TiO2 nanoparticles was introduced to explain the enhanced sensing performance of rGO/TiO2 layered film in contrast to bare rGO film.

This paper proposes an encrypted contactless charging system for roadway-powered electric vehicles (EVs), where the energy can be specifically transferred from the electric supply to authorized EVs. The key of the proposed energy encryption scheme is to utilize the random-like Gaussian map as the security key to chaotically regulate the charging circuit of the electric supply. In such way, the energy can be wirelessly transferred to authorized EVs, while unauthorized EVs cannot illegally acquire the electric energy without knowledge of the security key. Hence, the proposed energy encryption scheme can significantly improve the secure performance of the roadway EV charging system. In this paper, the simulated and experimental results are both provided to illustrate the effectiveness of the proposed the encrypted contactless charging system for multiple roadway-powered EVs.

Upon the increasing attentions on energy efficiency and hence environmental protection, the development of the electric vehicles (EVs) has been accelerating [1]. Particularly, the electronic differential (ED) system has been developed to eliminate the heavy gearbox for the curvilinear movement [2]. Yet, the traditional ED system is achieved by controlling each of the wheels independently, while fatal accidents might occur, followed by any calculation or feedback signal errors.

Mechanical gearbox, which plays significant roles in vehicular transmission system, inherently suffers from the drawbacks of wear-and-tear and regular maintenance [1]. Magnetic gears are considered as the preferred gearing device for vehicular transmission system because they have the merits of silent operation, maintenance free and physical isolation. However, the gear ratio of magnetic gear is fixed whereas the gear ratio in vehicular transmission system needs to be can be flexibly varied to fulfill for different driving requirements and road conditions.

In this paper, a new hybrid-excited flux switching (HEFS) machine with outer-rotor is proposed, which possesses distinct feature of high fault-tolerant operation. Comparing with the conventional permanent-magnet (PM) machine, it combines the merits of flux switching, low-cost, and high mechanical integrity [1]. Furthermore, its fault-tolerant feature ensures its continuous operation in the event of winding faults [2]. Hence, a new 12/10-pole HEFS machine is designed and implemented. The proposed machine showed in Figure 1 (a). The outer-rotor is merely a single piece iron, the stator contains 12-slots armature coils, 12-slots field excitation coils (FECs), and 12-pole PMs, where armature coils and FECs are located in alternate way.