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In this paper, an inductance on-line identification method is proposed for model predictive control (MPC) of vehicle-to-grid (V2G) inverter with enhanced robustness against grid frequency deviation. Firstly, a full-order sliding mode observer is established to observe the virtual-flux of the power grid. Secondly, a new inductance on-line identification method based on the dot product of the grid voltage vector and the observed virtual-flux vector is creatively proposed. A detailed theoretical analysis is carried out, which shows that the robustness of the proposed inductance identification method against frequency deviation can be enhanced by properly selecting sliding mode gains. Finally, by substituting the identified inductance into the MPC algorithm, the current control accuracy of the V2G inverter is improved accordingly. Detailed comparative experimental results verify the effectiveness and feasibility of the proposed strategy. When there is a frequency deviation of 5Hz, which may occur in a weak grid system, the inductance identification errors of the conventional gradient correction method, the forgetting-factor least squares method, and the direct calculation method are 2mH, 2.3mH, and 3mH, respectively, while it is reduced to 1.75mH for the proposed method.

This article deals with the problem of partial integrated guidance and control (IGC) design with fixed-time convergence. First of all, two new fixed-time stability systems are proposed, and a novel nonsingular terminal sliding mode with fixed-time convergence is constructed by switching the exponential term of system state variables, which can realize the transition from finite-time convergence to fixed-time convergence. Concurrently, in order to solve the singular problem of terminal sliding mode, a continuous piecewise function is used in the sliding mode surface design. Then, a novel nonsingular terminal sliding mode control with fixed-time convergence is proposed for partial IGC design; that is, the upper-bound of convergence time is independent of the initial states of both missile and target and can be set in advance. In addition, a radial basis function neural network (RBFNN) is used to adaptively estimate and compensate for the uncertainties caused by the target’s maneuvering, so that the design of fixed-time sliding mode controller does not need to know any information about the target maneuver in advance, which enables the proposed controller to be better with robustness. Finally, the effectiveness and merits of the proposed control strategy are shown by the numerical simulation results based on the nonlinear longitudinal model of missile.

This paper proposes a new extended state observer-based sliding-mode control strategy with prescribed-time convergence. Firstly, a novel prescribed-time extended state observer is designed, which estimates the disturbance accurately within a prescribed time and effectively solves peaking value problem. Secondly, a new type of second-order prescribed-time sliding-mode controller is designed to ensure system states converge within a prescribed time. Then, the proposed control strategy is applied to the design of partial integrated guidance and control with two-loop controller structure. Finally, the validity of the proposed methodology is verified through numerical simulation.

A model predictive control (MPC) strategy for grid-connected power converters is proposed in this article to reduce the current ripples without using ac voltage sensors. First, a sliding-mode observer is designed to estimate the grid voltage with an adaptive compensation algorithm. Thus, grid-voltage sensors are removed. The novelty of the proposed grid-voltage observation method is that it is inherent frequency adaptive without using the accurate grid angular frequency. By implementing the MPC strategy using the estimated grid voltage, the current ripples are reduced, especially under distorted grid-voltage conditions because of the low-pass filter used in the observer. Next, to further reduce the current ripples, a double-voltage vector-based MPC strategy is proposed based on the principle of the modulated MPC. Detailed theoretical analyses are also carried out to show its effectiveness for the first time. Finally, experimental studies are carried out to verify the validity of the proposed ac voltage sensorless MPC strategy.

In recent years, virtual synchronous generator (VSG) control algorithm has been widely studied in distributed grid-connected power inverters to deal with active and reactive power adjustment by simulating the operation principle of the actual synchronous generator. Nevertheless, once the current sensor fails, the grid-connected power inverter will lose its stability. To enhance the fault-tolerant operation ability of the grid-connected power inverter, a new inverter side current sensor-less model predictive control method based on sliding mode observer (SMO) is proposed. The stability of the SMO is analyzed by using the Lyapunov stability criterion. The gains of the SMO are then designed by analyzing their influences on the current and voltage observation based on the closed-loop transfer functions. Besides, to show the influences of the capacitance changes on the current observation, a detailed parameter sensitivity analysis is also carried out. Then, by using the estimated inductance current from the SMO, a current sensor-less model predictive control method is finally proposed. The main novelty of the proposed method is that both the output voltage of the inverter and the inverter side inductance are not required in the proposed SMO. So, the accuracy of current sensor-less control is improved. To verify the effectiveness of the proposed method, detailed experimental studies are carried out based on a Typhoon and PE-Expert 4 based experimental platform.

Modular multilevel converter (MMC) is a promising highly modular converter. However, the problems of voltage balancing control strategies in the MMC should be studied in detail. In order to improve...

Recently, model predictive control has been widely used to control grid-connected inverters due to its advantages. However, the conventional model predictive control methods usually require two AC voltage and current sensors to sample the grid voltages and currents. Particularly, the DC voltage sensor is also required to calculate the values of the voltage vectors. The inverter will lose its stability once these sensors fail. Thus, in this study, to improve the operational reliability of the grid-connected inverters, a sliding mode observer-based AC voltage sensorless model predictive control is proposed. First, a sliding mode observer is designed to estimate the grid voltage. Next, a new adaptive compensation strategy is proposed to remove the phase and amplitude errors caused by the low-pass filter. The main novelty of this compensation strategy is that it is immune to the actual grid frequency. Therefore, the grid voltage can be identified accurately, even under frequency deviation conditions. Besides, the stability and parameter designing method of the sliding mode observer is also analysed to provide a theoretical basis for its implementation. Finally, based on the observed grid voltage, the AC voltage sensorless model predictive control is achieved. Detailed comparative experimental results show the validity of the proposed method.

To suppress the common-mode voltage (CMV) and reduce the current total harmonic distortions (THDs) and ripples of two-level voltage source inverters (2L-VSIs), a hybrid voltage vector (VV) preselection-based model predictive control (MPC) strategy is proposed in this article. Six synthesized VVs (SVVs) are first defined based on the six nonzero VVs of the 2L-VSIs and a new SVV preselection strategy is proposed to reduce the CMV spikes caused by the dead time effects. Then, by dividing the three-phase current plane into seven sectors with an asymmetric hysteresis, a hybrid-VV preselection-based MPC strategy is finally proposed by considering the one step delay effects to completely remove the CMV spikes. Moreover, to further improve the parameter robustness of the proposed method, a control error compensation algorithm is also designed in this article. Simulation and experimental results show that the proposed hybrid-VV preselection-based MPC strategy can not only completely restrict the CMV within ± u dc/6, but also reduce the current THDs and ripples significantly. Additionally, the influences of the parameter variation on the proposed method are also reduced obviously.

The reliability and stability of a grid-connected converter is vital to the power conversion system. The faults of switching device and current sensor lead to operation failure for a grid-connected converter. An improved model predictive power control (MPPC) based on reconstructed currents is proposed for fault-tolerant operation of a grid-connected converter. Firstly, the three-phase currents are reconstructed using the sampled dc current and normal sensor information according to the relationship between the voltage vector and output currents. Secondly, the predictive power model is built based on fault-tolerant three-phase four-switch topology. Then the reconstructed current is used for the MPPC method. To keep the balance of dc capacitor voltages, the cost function is optimised and the switching vector, which minimises the cost function, is applied to the fault-tolerant converter. Finally, the experiment platform and simulation models are built to verify the proposed method. The results show that the proposed MPPC using reconstructed currents can keep the fault-tolerant operation of the grid-connected converter with sinusoidal currents and stable output power. The proposed method achieves the fault-tolerant operation under switching device and ac current sensor fault, which improve the reliability of the system.

Reliable communication between the primary and the secondary side is a challenge for simultaneous wireless information and power transfer (SWIPT) system. Considering many factors, such as cost, device size, and transmission efficiency, the SWIPT system transferring multiple frequencies with a single inductive link is an effective scheme to integrate reverse data communication. However, those SWIPT systems change power transfer frequency or power carrier amplitude while transferring information, then information cannot be transmitted when the inverter does not work, which reduces the reliability of communication. To solve this problem, this paper proposes an idea of establishing an independent information transfer channel, the power and information transmits at different frequencies. The information transmitted in the reverse direction no longer flows through the primary side inverter. It is guided to an independent channel after being transmitted to the primary side through the common inductive link. Its equivalent circuit model is provided to analyze the transfer gain, power transfer performance, and the relationship between the information coupling circuit and information transfer characteristics. Finally, a SWIPT prototype is built to validate the proposed SWIPT system.

Inductive pulsed power supply (IPPS) is considered as an alternative to capacitive one due to its higher energy density. An opening switch is necessary for an IPPS because it interrupts the charging circuit and transfers the stored energy to the load. A major technical challenge inherent to the IPPS is the overvoltage across the opening switch, i.e., the open-circuit voltage. Moreover, obtaining a larger current, especially with a steeper rising edge, will further increase the open-circuit voltage. A novel IPPS based on a three-winding pulse transformer, consisting of two primary windings and one secondary winding, is presented in this article to improve the output current and reduce the open-circuit voltage. The two primary inductors adopted a parallel switching scheme, namely, series charging and parallel discharging. Its working principle is analyzed first in detail. The theoretical analysis and simulation results have verified the superiority of the novel IPPS in improving the output current and reducing the open-circuit voltage.

In wireless power transfer (WPT) system, communication between the primary and the secondary plays an important role in system status monitoring and operation control. Bidirectional information transmission is also essential to detect the working state and send control command in both sides. This article proposes a bidirectional simultaneous wireless information and power transfer method. The secondary has a simple structure and employs only one switch. The proposed WPT system can achieve bidirectional information transmission via a sharing inductive link. The forward information is transferred by using a single full bridge inverter based on selected harmonic elimination PWM (SHEPWM) control methods without other high-frequency signal sources. In the secondary side, uncontrolled rectifier and a parallel MOSFET are adopted to realize constant voltage output and backward information transfer. The backward information modulation is achieved by changing the switching frequency of MOSFET. The forward and backward information demodulation modules are designed and analyzed in details. A 30W experiment platform with forward communication rate 5 kbps and backward communication rate 10 kbps is built to verify this proposed method.

To improve the fault-tolerant operation capability of bidirectional voltage source converter (BVSC), an improved model predictive current control (IMPCC) for fault-tolerant BVSC, is proposed with balanced DC-link capacitor voltage under unbalanced grid voltage. The proposed method can maintain continuous operation even if power device faults and unbalanced grid voltage faults occur together. A current predictive model of the fault-tolerant BVSC is established. By using grid voltages and 90° lagging signals in the αβ stationary coordinate system, the reference current calculation method is designed for BVSC to eliminate power ripple under unbalanced grid voltage, which can avoid the complex positive and negative sequence extraction. DC-link split capacitor voltage balancing is achieved by the improved cost function. Based on the current predictive model and improved cost function, the optimal space voltage vectors are selected for fault-tolerant BVSC. Compared to the existing predictive methods, the proposed IMPCC can balance DC-link capacitor voltage and eliminate the power ripples for fault-tolerant BVSC under unbalanced grid with simple implementation. The experimental results validate the effectiveness of the proposed control scheme.

This paper presents a double-vector-based model predictive control method for three-phase grid-connected AC/DC converters. The conventional model predictive control (MPC) presents high steady-state ripples due to the application of only one voltage vector during one control period. To reduce the current ripples, a new MPC method is proposed. Double-voltage vectors are selected and applied it each control period in the proposed method. To reduce the calculation burden, the duration time of each voltage vector is calculated based on the principle of modulated MPC. Furthermore, the effectiveness of the proposed double-voltage vector-based MPC strategy is analyzed in theory for the first time. Then, it is further verified by comparative experiment studies.

To reduce the common-mode voltage (CMV) and eliminate the CMV spikes for two-level voltage source inverters (2L-VSIs), an improved model predictive control (MPC) based CMV reduction method is proposed in this paper considering dead-time effects. First, an improved voltage vector (VV) preselection strategy is proposed to reduce the CMV spikes caused by the dead time. Second, a new hybrid VV preselection strategy based on a delay compensation strategy and a modified current sector division strategy is proposed to completely eliminate the CMV spikes. As the proposed hybrid VV preselection based MPC strategy makes full use of the six nonzero VVs of the 2L-VSI, the current total harmonic distortions and ripples are reduced. The simulation and experiments are carried out to verify the effectiveness of the proposed strategy.

In this paper, a fixed-time salvo attack guidance scheme with impact angle constraint on maneuvering target is proposed for multiple missiles by using the cooperative control strategy. A fixed-time extended state observer is introduced to accurately estimate the target accelerations. The proposed guidance scheme is divided into parts, that is, the guidance law on the normal direction of the line of sight (LOS) and that along the LOS direction, of which the former one ensures the LOS angle converge to the desired value in fixed-time, and the latter one ensures the relative range consensus error converges to origin in fixed time, so as to achieve the salvo attack. Simulation results are given to demonstrate the effectiveness of the proposed scheme.

This paper proposes a new extended stateobserver-based sliding mode control strategy with prescribed finite-time convergence. Firstly, a novel prescribed finite-time extended state observer is designed, which estimates the disturbance accurately within a prescribed finite time and effectively solves peaking value problem. Secondly, a new type of second-order prescribed finite-time sliding mode controller is designed to ensure system states converge within a prescribed finite time. Then, the proposed control strategy is applied to the design of partial integrated guidance and control with two-loop controller structure. Finally, the validity of the proposed methodology is verified through numerical simulation.

Communication between the primary and secondary sides is pivotal to the wireless power transfer (WPT) system. The system control commands and feedback information need simultaneous wireless information and power transfer (SWIPT). In this paper, a FSK-based SWIPT system with full-duplex communication via a shared channel is provided. Considering the complexity of the coupling relationship in this kind of full-duplex SWIPT system, this paper proposes an analysis method based on the transmission channel, studies the crosstalk between the power channel and the information channel, and between the forward and reverse transfer of information. A design method of full-duplex communication SWIPT system based on shared coupling channels is provided. A 60 W SWIPT prototype with a full-duplex communication rate of 20 kbps is built to verify the proposed method. Web of Science 14 16 art. no. 4918

Due to the large-scale renewable energy connected to the power grid by power electronic converters, the inertia and stability of the power grid is declining. In order to improve the inertia and support the grid recovery, the three-phase converter works as a virtual synchronous generator (VSG) to respond to the frequency and voltage changes of the power grid. This paper proposes a model predictive control for the virtual synchronous generator (MPC-VSG) strategy, which can automatically control the converter output power with the grid frequency and voltage changes. Further consideration of fault-tolerant ability and reliability, the method based on improved voltage vector selection, and reconstructed current is used for MPC-VSG to ensure continuous operation for three-phase converters that have current-sensor faults, and improve the reconstruction precision. The proposed method can respond to the frequency and voltage changes of the power grid and has fault-tolerant ability, which is easy to realize without pulse width modulation (PWM) and a proportional-integral (PI) controller. The effectiveness of the proposed control strategy is verified by experiment.

International audience; The detection of eye torsion is an important element for diagnosis of balance disorders, although it is rarely available in existing eye tracking systems. A novel method is proposed in this paper to provide robust measurement of torsional eye movements. A numerical approach is presented to estimate the iris boundary only according to the gaze direction, so the segmentation of the iris is more robust against occlusions and ambiguities. The perspective distortion of the iris pattern at eccentric eye positions is also corrected, benefiting from the transformation relation that is established for the iris estimation. The angle of the eye torsion is next measured on the unrolled iris patterns via a TM (Template Matching) technique. The principle of the proposed method is validated and its robustness in practice is assessed. A very low mean FPR (False Positive Rate) is reported (i.e., 3.3%) in a gaze test when testing on five participants with very different eye morphologies. The present method always gave correct measurement on the iris patterns with simulated eye torsions and rarely provided mistaken detections in the absence of eye torsion in practical conditions. Therefore, it shows a good potential to be further applied in medical applications.

Recently, model predictive control (MPC) methods have been widely used to achieve the control of two-level voltage source inverters due to their superiorities. However, only one of the eight basic voltage vectors is applied in every control cycle in the conventional MPC system, resulting in large current ripples and distortions. To address this issue, a dual-vector modulated MPC method is presented, where two voltage vectors are selected and utilized to control the voltage source inverter in every control cycle. The duty cycle of each voltage vector is figured out according to the hypothesis that it is inversely proportional to the square root of its corresponding cost function value, which is the first contribution of this paper. The effectiveness of this assumption is verified for the first time by a detailed theoretical analysis shown in this paper based on the geometrical relationship of the voltage vectors, which is another contribution of this paper. Moreover, further theoretical analysis shows that the proposed dual-vector modulated MPC method can also be extended to control other types of inverters, such as three-phase four-switch inverters. Detailed experimental results validate the effectiveness of the presented strategy.

Model predictive control (MPC) strategies have been frequently studied in recent years. To reduce the common-mode voltage (CMV) as well as the current total harmonic distortions (THDs) of the 2-level voltage sources (2L-VSIs), a new MPC strategy is proposed in this study considering both the dead-time and the one-step delay effects. First, the reference voltage vector (VV) prediction based MPC strategy is utilised as it is simple and accurate. Next, the VV preselection strategy is studied in detail to remove the CMV spikes. The effects of the dead time on the CMV are analysed, and an improved VV preselection strategy is presented to reduce the CMV spikes. Then, the one-step delay effects are also analysed, and further improvements are made to completely remove the CMV spikes. Moreover, the maximum variation of the current during one control period is studied in-depth to provide a solid theory foundation for dividing the current sector more accurately. As the six non-zero VVs of the 2L-VSI are fully used in the proposed method, not only the CMV but also the current THDs are reduced. Finally, comparative simulation and experimental studies are carried out to validate the effectiveness of the proposed method.

The hybrid electric bus (HEB) presents an emerging solution to exhaust gas emissions in urban transport. This paper proposes a multiport bidirectional switched reluctance motor (SRM) drive for solar-assisted HEB (SHEB) powertrain, which not only improves the motoring performance, but also achieves flexible charging functions. To extend the driving miles and achieve self-charging ability, photovoltaic (PV) panels are installed on the bus to decrease the reliance on fuelsbatteries and charging stations. A bidirectional front-end circuit with a PV-fed circuit is designed to integrate electrical components into one converter. Six driving and five charging modes are achieved. The dc voltage is boosted by the battery in generator control unit (GCU) driving mode and by the charge capacitor in battery driving mode, where the torque capability is improved. Usually, an extra converter is needed to achieve battery charging. In this paper, the battery can be directly charged by the demagnetization current in GCU or PV driving mode, and can be quickly charged by the PV panels and GCUAC grids at SHEB standstill conditions, by utilizing the traction motor windings and integrated converter circuit, without external charging converters. Experiments on a three-phase 128 SRM confirm the effectiveness of the proposed drive and control scheme.

This paper proposes a simplified and improved model predictive current control (MPCC) scheme for grid-connected bidirectional voltage source converter (GC-BVSC) when the unbalanced grid voltages occur. In conditions of unbalanced grid voltage, the current harmonic components of the GC-BVSC increase significantly, and twice grid-frequency ripple exist in both active power and reactive power, which influence the output power quality. To reduce harmonic currents and power fluctuations, an improved MPCC (IMPCC) method is proposed, and a two-step predictive model of GC-BVSC is put forward. The current compensation values are expressed by grid voltages and their quadrature signals that lag 90 electrical degrees in the αβ stationary coordinates system. The cost function reducing both the power ripple and current distortion is designed. Compared to conventional methods, phase-locked loop, pulse width modulation, and complex positive and negative sequence extraction of grid voltage are not required. In addition, IMPCC presents a better performance by reducing both grid-connected current harmonics and power ripple of GC-BVSC with flexible bidirectional power regulation capability. Simulation and experimental results on power electronics-professional (PE-PRO) platform verify the effectiveness of the proposed scheme under both single-phase and three-phase unbalanced grid voltages.

By virtue of the method of integration within ordered product (IWOP) of operators we find the normally ordered form of the optical wavelet-fractional squeezing combinatorial transform (WFrST) operator. The way we successfully combine them to realize the integration transform kernel of WFrST is making full use of the completeness relation of Diracʼs ket–bra representation. The WFrST can play role in analyzing and recognizing quantum states, for instance, we apply this new transform to identify the vacuum state, the single-particle state, and their superposition state.

The bidirectional ac/dc converter is widely used to realize the power conversion between ac and dc microgrid, but the faults of switch devices and unbalanced grid voltages may lead to the decline of power quality and affect normal operation of the converter. The four-switch three-phase (FSTP) fault-tolerant structure is reconstructed from a six-switch three-phase structure with switch device fault. In order to reduce harmonic currents and output power fluctuations under unbalanced grid voltages, finite states model predictive direct power control (MPDPC) with power compensation method is proposed for FSTP structure and predictive power model of the bidirectional FSTP ac/dc converter is established. The power compensation values are expressed by grid voltages and their quadrature signals that lagging 90 electrical degrees in the αβ stationary coordinate system. Compared with the conventional method, phase-locked loop, pulse width modulation, and complex positive-/negative-sequence extraction of grid voltage are not required. Ripples of active power or reactive power under unbalanced grid voltages are eliminated. The proposed fault-tolerant MPDPC with power compensation method ensures the continuous and reliable operation of the bidirectional ac/dc converter with high power quality. Simulation and experimental results are presented to validate the proposed control strategy under symmetrical unbalanced grid voltages with switch device faults.

Pneumoconiosis remains one of the most common and harmful occupational diseases in China, leading to huge economic losses to society with its high prevalence and costly treatment. Diagnosis of pneumoconiosis still strongly depends on the experience of radiologists, which affects rapid detection on large populations. Recent research focuses on computer-aided detection based on machine learning. These have achieved high accuracy, among which artificial neural network (ANN) shows excellent performance. However, due to imbalanced samples and lack of interpretability, wide utilization in clinical practice meets difficulty. To address these problems, we first establish a pneumoconiosis radiograph dataset, including both positive and negative samples. Second, deep convolutional diagnosis approaches are compared in pneumoconiosis detection, and a balanced training is adopted to promote recall. Comprehensive experiments conducted on this dataset demonstrate high accuracy (88.6%). Third, we explain diagnosis results by visualizing suspected opacities on pneumoconiosis radiographs, which could provide solid diagnostic reference for surgeons.

The wireless power transfer (WPT) technology has the advantages of convenience, safety and reliability due to its non-metal contact power supply and has a broad application prospect in many occasions. In practical applications, the information communication between the primary and secondary side is necessary for output voltage control, load detection, condition monitoring and other functions, which makes the WPT system more intelligent and convenient. A simultaneous wireless information and power transfer (SWIPT) system with controlled chopper circuit receiver is proposed in this paper. The load voltage remains constant by adjusting the pulse width of the secondary controlled device through feedback control. The information bidirectional transmission methods and two modes are proposed, considering different application scenarios. Simulation and experiment results validate the proposed topology and the method of information bidirectional transmission.

With the development of power electronics, wireless power transfer (WPT) technology has been widely used in many fields because of its convenience and safety. In this paper, a multi-frequency wireless power and information transfer system with common inductive coils is proposed by using the multi-frequency programmed pulse width modulation (MFPWM) technology, which applies double modules to realize the power and data transmission with a single full-bridge inverter. The performances of the power and data transfer, as well as the principles of the control strategy are analyzed in detail. It shows that the power and data can share a pair of common couple coil and a single inverter. A simulation model is designed to verify the effectiveness of the proposed method and structure. The system demonstrates stability and feasibility under this control strategy.

In the three-phase four-wire power distribution system under unbalanced power grid, the neutral line current generates zero sequence current due to increasing nonlinear and unbalanced loads. A model predictive control (MPC) strategy is proposed and applied to the split-capacitor-type structure. To compensate the zero-sequence current, an optimal voltage vector which can minimize the cost function is selected and then applied to the next period. Finally, the simulation results show that the proposed control strategy has good practicability.

In the conventional structure of simultaneous wireless information and power transfer (SWIPT) system, the information channel depends on power transmission, which means if there is no power transfer, then all switches in the inverter are turned off, it is impossible to transfer information anymore. Therefore, an improved structure of SWIPT system with independent information channel is proposed in this paper. This paper establishes the model of the structure and analyzes the power and information channel of the system to verify the feasibility of the structure. Theoretical analysis and simulation results validate the proposed conception of information transmission with an independent channel.

In this paper, a novel wireless power transfer (WPT) system is proposed. It realizes the WPT on the shared channel with the capability of full-duplex signal transmission. The main structure of the system contains two dual full bridges topology to achieve bidirectional and controllable power transmission. Signal transmission is coupled into the circuit using four tightly coupling transformers (two transmitters and two receivers). Based on this structure, the influence of signal channel on the power transmission is analyzed. The forward and reverse information transfer gains are analyzed separately to obtain their Bode diagrams, which proves that the different frequencies could be transferred through the common shared channel simultaneously. Simulation results validate the feasibility of the proposed scheme.

In wireless power transfer (WPT) system, the primary and secondary sides employ full bridges to transfer power. The direction of power transmission is controlled by shifting the phase angle. In this paper, a method of bidirectional power trabsfer and information reverse transmission is proposed for the bidirectional WPT system with dual active bridges through a shared inductive channel. In order to realize the information reverse transmission during power transfer, a new magnetic coil is added to the main circuit. The analysis of transfer function validates the shared channel carrying two frequencies is able to transfer power and information simultaneously. The simulation verifies the proposed method of information reverse transmission.

Bidirectional AC/DC converter can be reconstructed as a three-phase four-switch (TPFS) fault-tolerant converter when leg fault occurs to enhance its fault tolerant operation capability. In this paper, to further improve the control performance of the TPFS fault-tolerant converter, a new model predictive control (MPC) method is proposed. Considering that there are only four voltage vectors for the TPFS fault-tolerant converter, to reduce the current ripples, double voltage vectors are selected and applied per control period in the proposed method. To reduce the calculation burden, the duration time of each voltage vector is calculated based on the principle of the modulated MPC. Furthermore, the effectiveness of the proposed double-voltage vector based MPC strategy is analyzed in theory in detail for the first time and then it is further verified by comparative simulation studies.

To identify the grid impedance accurately, high frequency non-characteristic harmonic voltages and currents are often injected into the grid by the power converter firstly. Then, digital signal filters are used to extract the high frequency voltages and currents from the sampled voltages and currents at the point of common coupling. Finally, the grid impedance can be calculated. Due to effects of the grid background harmonics, such as 5th and 7th harmonic, the grid impedance identification precision is usually poor. In this paper, to improve the grid impedance identification precision, a new complex coefficient filter-based grid impedance identification method is proposed considering the effects of the grid background harmonics. To reduce the influences of the grid background harmonics, such as 5th and 7th harmonic, an improved complex coefficient filter is proposed by adding a 5th and 7th harmonic suppression module to the conventional complex coefficient filter. The filter characteristic of the proposed complex coefficient filter is analyzed in detail to show its properties. Additionally, a simplified implementation method of the proposed complex coefficient filter is also proposed to reduce the calculation burden. Finally, simulation studies are carried out to further show the effectiveness of the proposed grid impedance identification method.

Communication between primary and secondary side controllers is essential in practical applications of inductive power transfer (IPT) systems, which is generally realized by specific modules. However, such additional components increases the cost and the volume of the receiver. Therefore, this paper develops a novel simultaneous wireless information and power transfer (SWIPT) technique through a single-switch active receiver. The desired output voltage can be obtained by regulating the duty ratio of secondary side switch, and the information can be transmitted to the primary side by controlling the frequency of that switch. The proposed receiver advances in cost reduction, simple design, and easy realization of information exchange and power regulation. Experimental results are added to verify the proposed system.

Safety problem is of great importance for the wireless EV charger since a paperclip is overheated in several minutes for 6.6 kW wireless power transfer (WPT). In this paper, a statistical model of foreign object detection (FOD) is proposed to improve the sensitivity of metal detector and to reduce false alarm. The basic detection principle is to use the induced voltage signal of differential coils placed on the surface of ground side (GA). A pair of DQ coils was fabricated for collecting signal. A normal distribution is assigned to the signal while generalized likelihood ratio test (GLRT) is applied to figure out the detector with the best performance. Based on the proposed model, the effect of power swing originated from maximum efficiency point tracking can be effectively eliminated. In the experiment, many hazardous metallic objects can be well detected on the surface of GA. It is proved that this model is suitable for FOD function in high power WPT system.

To ensure alignment during wireless power transfer (WPT) of electric vehicles (EVs), position detection (PD) during parking is needed. In this paper, a low frequency (LF) positioning method based on eigenvector lookup is proposed, which is suitable for complex environment and easy to implement with simple algorithm. To reduce the calibration work and data storage, this paper proposes a simple method to decoupling the position and the rotation angle of vehicles by finding an eigenvector only corresponding to the position, independent of the angle. The real-time position is determined by comparing the similarity between the target vector formed by current induced voltages on sense coils and the eigenvector. A simple method of calculating rotation angle is also proposed. The feasibility of the proposed methods has been verified by simulation and experiments. The accuracy of detected position is less than 5% and the angle deviation is less than 10 degrees.

Sliding mode observers are often utilized to achieve the speed sensorless control of permanent magnet synchronous motors. However, due to the nonlinearity of the sampling channel, DC offset is often contained in the sampled voltages and currents of the permanent magnet synchronous motor, which may further reduce the speed sensorless control accuracy. Besides, the speed sensorless control accuracy is usually very poor due to the low signal-to-noise ratio in the low speed region. In this paper, to improve the speed sensorless control accuracy in the low speed region and remove the effects of the DC offset, a new super-twisting sliding mode observer based speed sensorless control method is proposed for permanent magnet synchronous motors. First, based on the concept of the equivalent feedback, a new super-twisting sliding mode observer is proposed. Second, the effects of the DC offset on the speed sensorless control are analyzed in detail, and a second-order generalized integrator is used to remove the DC offset contained in the observed equivalent feedback signal. Then, a phase-locked loop is used to estimate the speed and the rotor position to achieve speed sensorless control. Finally, the effectiveness of the proposed control strategy is verified by a 6.6 kW permanent magnet synchronous motor speed sensorless control system.

Time geography represents the uncertainty of the space–time position of moving objects through two basic structures, the space–time path and space–time prism, which are subject to the speed allowed in the travel environment. Thus, any attempt at a quantitative time-geographic analysis must consider the actual velocity with respect to space. In a trip, individuals tend to pass through structurally varying spaces, such as linear traffic networks and planar walking surfaces, which are not suitable for use in a single GIS spatial data model (i.e., network, raster) that is only applicable to a single spatial structure (i.e., point, line, polygon). In this study, a velocity model is developed for a traffic network and walking surface-constrained travel environment through the divide-and-conquer principle. The construction of this model can be divided into three basic steps: the spatial layering of the dual-constrained travel environment; independent modelling of each layer using different spatial data models; and generation of layer-based time-geographic framework by merging models of each layer. We demonstrate the usefulness of the model for studying the space–time accessibility of a moving object over a study area with varying spatial structures. Finally, an example is given to analyse the effectiveness of the proposed model.

So as to reduce the current harmonics and power ripple after bidirectional AC/DC converter bridge arm fault, a multi-vector model predictive fault-tolerant control method is proposed. First, the system of bidirectional AC/DC converter with a bridge arm fault is reconstructed. Then the operation mechanism of fault-tolerant converter structure and the relationship of voltage vectors are clarified. Second, the power prediction model under the converter fault-tolerant operation mode is established. Multiple voltage vectors are used in a switching cycle. The new synthetic vector is used to track the optimal vector. The switching order of each vector is fixed to realize switching frequency concentrate. Third, the simulation model is built. The results show that the bidirectional AC/DC converter can operate fault-tolerant operation after the bridge arm failure under the control strategy proposed and the output current harmonics and power ripples are reduced. The system has good steady-state and dynamic performance.

This paper proposes an alterable structure power router (PR) topology which shares the ability of general Alternating Current (AC) and Direct Current (DC) port. This alterable structure PR aims to better implement the interconnections among micro-grids, renewable energy, and traditional grids. The PR’s converter structure is alterable according to the system power. Based on the operation analysis of the PR, the mathematic model of the power router is established and the relationship between switch states and port voltage is analyzed. According to the PR mathematical model, the control method is designed to realize current control in both AC and DC mode. With the proposed power router topology, the PR’s port can be used in both AC and DC situations, which saves the cost of traditional PRs and increases economic efficiency. The simulation and experimental results prove the good steady-state and dynamic performance of the proposed power router topology.

To better implement the interconnections among micro-grids, renewable energy and traditional grid, a novel power router topology is proposed in this paper. It enjoys the advantages of bidirectional power flow, plug-and-play and a general AC and DC port. The power router consists of a converter, a filter and a standard information interface. The converter’s topology has various choices according to the power level of the system. The output filter switches between LC filter and LCL filter according to the converter’s operation mode. The standard information interface grants the power router the ability of plug-and-play. The filter is designed to give the best transient response. Simulation results are presented in this paper to prove the effectiveness and feasibility of the proposed power router topology.

This study establishes a short-time stochastic subspace identification (ST-SSI) framework to estimate bridge frequencies by processing the dynamic response of a traversing vehicle. The formulation uses a dimensionless description of the response that simplifies the vehicle-bridge interaction (VBI) problem and brings forward the minimum number of parameters required for the identification. With the aid of the dimensionless parameters the analysis manages to successfully apply ST-SSI despite the time-varying nature of the VBI system. Further, the proposed approach eliminates the adverse effect of the road surface roughness using a transformed residual vehicle response obtained from two traverses of a vehicle at different speeds over the bridge. The study verifies the proposed ST-SSI approach numerically: it first performs the dynamic VBI simulations to obtain the response of the vehicle, and then applies the proposed ST-SSI method, assuming the dynamic characteristics of the vehicle are available. The numerical experiments concern both a sprung mass model and a more realistic multi-degree-of-freedom (MDOF) vehicle model traversing a simply supported bridge. The results show that the proposed approach succeeds in identifying the first two bridge frequencies for test-vehicle speeds much higher (e.g., 10 m/s = 36 km/h and 20 m/s = 72 km/h) than previously considered, even in the presence of high levels of road surface roughness.

In wireless charging devices, a transmitter that applies a single inverter to output dual-frequency can effectively solve the charging incompatibility problem caused by different wireless charging standards and reduce the equipment volume. However, it is very difficult to solve the switching angle of the modulated dual-frequency waveform, which involves non-linear high-dimensional multi-objective optimization with multiple constraints. In this paper, an improved differential evolution (DE) algorithm is proposed to solve the transcendental equations of switching angle trains of dual-frequency programmed harmonic modulation (PHM) waveform. The proposed algorithm maintains diversity while preserving the elites and improves the convergence speed of the solution. The advantage of the proposed algorithm was verified by comparing with non-dominated sorting genetic algorithm II (NSGA II) and multi-objective particle swarm optimization (MOPSO). The simulation and experimental results validate that the proposed method can output dual-frequency with a single inverter for wireless power transfer (WPT). Web of Science 13 9 art. no. 2209

In order to keep the load voltage stable in the simultaneous wireless information and power transfer (SWIPT) system, the information transmission between the primary and secondary sides is required. A SWIPT system with controlled chopper circuit receiver is proposed in this paper. The secondary side has only one controlled power electronic device that enables chopper control. The relationship between the primary phase angle, the secondary controlled device voltage angle and the load voltage is obtained through theoretical analysis. The secondary side adjusts the voltage angle of the controlled device through the feedback control to achieve a stable load voltage. The signal is modulated by changing the power transmission frequency and the switching frequency of the secondary full controlled device to transfer the information forward and backward respectively. Simulation proves that the proposed structure can realize a stable output of 50V load voltage and bidirectional transmission of information at a rate of 2kbit/s.

Recently, wireless power transfer (WPT) systems with active receivers have been proposed for conduction loss reduction, bidirectional power transfer and efficiency improvement. However, the synchronization of WPT systems is complex in nature with the selection of high operating frequencies. Without proper synchronization, power oscillations appear and the system can become unstable. In this paper, a detailed analysis of different WPT systems is presented and the essence of the synchronization technique is derived as being composed of two functions: independent frequency locking and reference phase calibration. The voltage across the receiver-side compensation capacitor is divided and utilized for frequency locking, whereas the reference phase calibration is realized through software code. The proposed method is effective and easy to implement, with a lower overall cost due to its simplicity. The technique can work effectively at high frequency and withstand large variations of operating frequency, load and mutual inductance. In addition, it can address the synchronization problem of multiple active receiver WPT systems with and without cross coupling among the receiving coils. Theoretical analysis and experimental results validate the proposed technique.