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In this paper a finite control set model predictive control is used to track a current reference in a power converter connected to an RL load. An artificial intelligence (AI) approach is presented for real-time determination of the weighting factor that regulates the average switching frequency, independently of the operating point. The paper focuses on the design, training, and digital implementation of an artificial neural network (ANN) that can be developed in a low-cost control platform. It is presented a sampling and offline ANN training procedure, together with a low-cost hardware implementation based on integer quantization of the ANN. The above approach provides a standalone application, serving as a framework for development of ANN applications for power-converters. The main advantage of the presented approach is that the ANN inference is executed in real-time. In this way, the weighting factor is automatically updated in real-time, allowing the system to quickly adapt to any reference step changes, and consequently provide the desired behavior. Executing the setup in laboratory prototype confirmed the theoretical analysis and successful tracking of the reference frequency.

This paper investigates the effects of the signal average power and the ambient temperature on the behavioral modeling and pre-distortion of high-power amplifiers concurrently. The measurement results showed that in addition to the signal average power, the behavior of a high-power PA is a function of ambient temperature as well. This paper proposes a novel smart Digital Pre-Distortion (DPD) model that considers both average Power and Temperature (PTI-DPD). The PTI-DPD is implemented using Artificial Intelligence (AI) based model and it benefits from sets of data formats containing the signal, its delayed versions, signal average power, and ambient temperature. The devised apparatus provides an uninterrupted linearization across the ambient temperature and signal average power span without need for any feedback or multiple models. A series of measurements have been conducted to study the PTI-DPD performance across the temperature and average power range. According to the results, the PTI-DPD achieves an average of -48.5 dBc Adjacent Channel Power Ratio (ACPR) across the average power and temperature span.

This paper proposes a low-profile coplanar magnetic coupling resonance wireless power transfer system, which can be expanded segment by segment to power more receivers over a long distance with load-independent constant current output. Due to the low structural profile, it can easily conform to the environment such as desktops, floors, and walls, occupying a small space. By placing low-profile ferrite plates on or under the junctions of adjacent coplanar coils, the main coupling coefficients of the adjacent coils are significantly enhanced and therefore the power transmission efficiency (PTE) of the system is greatly improved. With the fixed operating frequency, load- independent current characteristics, simple structure, coplanarity with the environment, good scalability and high PTE, the system can be easily utilized in various medium and long-range multi- load WPT applications. The paper describes its principle in detail and clarifies the influence of losses on system performance such as output current characteristics, PTE and the maximum number of the charging segments. The experimental platform with two and three receivers was established to verify the theory, and the measurement results are in good agreement with the theoretical analysis. The maximum measured PTE reached 93.8% and 93.6% for two and three receivers, respectively.

Ring and meshed dc distribution grids have attracted increasing interest lately. Their multi-point and multi-terminal structure facilitates flexible operational control and reliable power supply across the network. However, the systems implemented with existing power converters lack sufficient control freedoms for proper power flow adjustment; therefore, it is necessary to develop additional dc power flow controllers (DCPFCs) to be added to these grids for improved power flow control capability. Specific to multi-terminal dc networks built with modular multilevel converters (MMCs), this paper proposes an embedded DCPFC (e-DCPFC) directly integrated in the MMC topology. Unlike previously proposed solutions, the e-DCPFC configuration is derived from the conventional MMC and does not need any isolation transformers or external power supply. Its other main features include modular construction, convenience for multiport extension and bipolar regulating capacity. In this paper, the topology, working principle, and the coordinated control strategy for e-DCPFC and its host MMC are elaborated. Experimental results from a lab prototype verify the proposed topology and its performance under typical working conditions.

In this paper, a hybrid Modular multilevel converter (MMC) topology is proposed, in which two of the submodules (SMs) are based on SiC MOSFET, while others are based on Si IGBT. In the proposed hybrid topology, the capacitor voltage of SiC SM is controlled to be half of that of Si SM, which reduces the requirement for the SiC devices. Whats more, this paper improves the modulation scheme to move most of the switching actions from Si SMs to the two SiC SMs, which strengthens the merits and avoids the shortcomings of SiC MOSFET. Besides, to solve the voltage imbalance problem caused by the change of topology and modulation scheme, a specialized voltage balancing scheme is proposed. Finally, the simulation and experiment result proves the feasibility of the hybrid MMC and control scheme, and the comprehensive analysis verifies that the hybrid MMC can achieve a better balance among cost, loss and feasibility compared with others.

This paper proposes a straightforward and effective control strategy to reduce the periodic speed ripple of the permanent-magnet synchronous motor (PMSM). The control strategy can be described as injecting current harmonics whose amplitude and phase can be adjusted automatically to compensate for periodic speed ripple. Compared with the resonant controller with the Tustin transform, the method proposed in the paper can track speed ripple frequency without frequency displacement, realizing no steady-state error. Besides, the system stability is analyzed, and the phase compensation scheme is proposed to increase the phase stability. Moreover, the equivalence between the harmonic injection module and the resonant controller has been analyzed, which provides a simple way to understand the phase compensation of the resonant controller. The theoretical analysis and experimental results are presented to verify the feasibility of the proposed harmonic injection method.

This paper addresses the problem of proper flicker severity assessment by smart energy meters. Flicker severity occurs for a typical voltage clipped cosine distortion caused by operation of power electronic devices in the power grid. The voltage distortion caused only by higher harmonics does not cause voltage fluctuations, and therefore does not cause flicker. This paper presents the research results for some models of Advanced Metering Infrastructure (AMI) smart meters, for which irregularities are observed in the voltage variation severity assessment if the typical voltage distortion occurs in the power grid. Possible mistakes in implementation of flickermeter signal chain as defined by International Electrotechnical Commission (IEC) in smart meters that influence the measurement results have been explained. The analysis of the influence of typical voltage distortion on the indicator Pst measurement has been carried out analytically and in numerical simulation studies using the modeled flickermeter signal chain.

Existing studies about the harmonic analysis of grid-connected converters (GCCs) mainly focus on the frequency range below Nyquist sampling frequency (NSF) or switching frequency (SF) to make full use of linearization. However, in some actual high-power industrial applications, e.g. electric railways or wind power generation, harmonic problems are challenging in a wide frequency that can be as high as thousands of hertz. This is much higher than the NSF and SF. In order to bridge the gap, this paper extends the harmonic analysis frequency to the entire frequency range by addressing the aliasing effect and sideband effect. These two effects can be neglected at the low frequency for simplification while they will make great differences at the high-frequency, as demonstrated in this paper, due to the frequency coupling and nonlinear characteristics. In this regard, a regression method based on an artificial neural network (ANN) is used to map the in-out relation of the pulse width modulation (PWM) process. By adopting the methodology of this paper, harmonic performances of GCCs can be analyzed comprehensively and explicitly in terms of harmonic instability, harmonic resonance, harmonic overvoltage, filter design and so on. Finally, Experiments are presented to verify the effectiveness and accuracy of the analysis.

In this paper, a novel optical rotary sensor based on laser self-mixing interferometry is developed for the full-circle rotation measurement. The proposed sensor is convenient to use for it does not need any contact with the target or a cooperative mirror. A prototype is fabricated and tested. The measured results demonstrate a good performance compared with other optical rotary sensors, in terms of the 0.1 μrad resolution, the 2.33×10-4 linearity and 2 μrad stability over one hour. Additionally, the repeatability error is below 14.66 mrad under 9-group full-circle tests, which exhibits the potential to be instrumentalized reliably. Error analysis and limitation discussion have been also carried out. Although the accuracy needs further improvement compared with the best rotary sensor, this method has its unique advantages of high resolution, non-cooperative target sensing and electromagnetic immunity. Hence, the proposed optical rotary sensor provides a promising alternative in precise rotation measurement, tremor tracing and nano-motion monitoring.In this paper, a novel optical rotary sensor based on laser self-mixing interferometry is developed for the full-circle rotation measurement. The proposed sensor is convenient to use for it does not need any contact with the target or a cooperative mirror. A prototype is fabricated and tested. The measured results demonstrate a good performance compared with other optical rotary sensors, in terms of the 0.1 μrad resolution, the 2.33×10-4 linearity and 2 μrad stability over one hour. Additionally, the repeatability error is below 14.66 mrad under 9-group full-circle tests, which exhibits the potential to be instrumentalized reliably. Error analysis and limitation discussion have been also carried out. Although the accuracy needs further improvement compared with the best rotary sensor, this method has its unique advantages of high resolution, non-cooperative target sensing and electromagnetic immunity. Hence, the proposed optical rotary sensor provides a promising alternative in precise rotation measurement, tremor tracing and nano-motion monitoring.

This paper focuses on solving the problem of precise peg-in-hole assembly. This paper aims at realizing the insertion assembly tasks of cylindrical or prismatic objects with clearance or interference fit. First, a feature space and a response space are constructed according to the relative pose and equivalent forces and moments. Then the contact states are segmented in the feature space and the segmentation boundaries are mapped into the response space. Further, a feature-based compliance control (FBCC) method is proposed based on boundary mapping. In FBCC method, a direction matrix is designed to execute accurate adjustment and an integral element is applied to eliminate residual responses. Finally, the simulations and experiments demonstrate the superiority and robustness of FBCC method.

This paper proposes a primary-side linear control strategy to realize the constant current (CC)/voltage (CV) charging for the wireless power transfer (WPT) system, based on the LCC-N circuit. Different from the conventional compensation topology used in control strategies, this paper combines magnetic integration structure on the primary side and non-compensation topology on the secondary side. Firstly, the LCC-N magnetic integration and non-compensation topology is introduced. An improved parameters identification method considering the non-pure resistive input impedance characteristics of the rectifier is proposed to identify the current, voltage and equivalent resistance of the load, based on the LCC-N topology. In the process of identification, the relationship between the input impedance of the rectifier and the load is needless. Then, according to the LCC-N output characteristics and identified load parameters, the relationship between the input voltage and load current and voltage is simplified to linear through the linear superposition of fundamental wave and third harmonic. A linear control strategy on the primary side is proposed to achieve CC/CV output. Finally, a 1 kW WPT prototype is built. The experimental results show that the maximum error of the output current and voltage are 1.8% and 1.2% during the CC and CV charging, respectively.

Vernier reluctance machine with DC field coils in stator is a competitive rare-earth-free design for variable-speed industrial applications due to its robust structure and controllable excitation, while its torque density is relatively disadvantageous. To address this issue, this paper proposes a new armature winding design method for VRM with DC field coils across two stator teeth. The key is to break the traditional winding design principle based on the flux modulation effect of fundamental DC field harmonic, and instead, reconstruct a novel harmonic winding to enhance the utilization factor of the modulated high-order DC field harmonics. By this means, the torque density can be improved by 75.6% compared to the existing poor counterpart. In this paper, the machine structure and operation principle are introduced, with emphasis on the high-order DC field harmonics distribution rule and its influence on the armature winding design. By finite element design and optimization, a comparative study is performed to evaluate the machine performance using two different winding configurations with variable slot pole combinations. A prototype is fabricated and tested, and the results agree well with finite element analysis, which verifies the feasibility and advantages of the proposed winding design method.

This paper presents a partial-power post-regulated LLC resonant converter. In the proposed topology, the input power is first transferred to the secondary side of the transformer through the LLC-DCX converter to achieve galvanic isolation and voltage conversion functions. Then, most of the power is directly transmitted to the load side, and only a small portion of the power is converted to the output side by the partial-power processing converter (PPC). Therefore, unlike the two-stage solution, the converter proposed in this paper achieves output voltage regulation while minimizing the efficiency loss caused by the two-stage conversion. The operating principle of the proposed converter is analyzed, and the system prototype is constructed. Experimental result validates the correctness of the analysis and proves the feasibility of the proposed converter.

This paper proposed a simplified flying capacitor voltage (FCV) control strategy based on hybrid clamped three-level boost converter (HC-TLBC). Compared with the traditional control method, the proposed method does not need the sampling of the FCV and the extra FCV control loop. Hence, the software and hardware resources, like sampling circuits and control algorithm, can all be saved significantly especially in high voltage photovoltaic system (HVPS) with multiple dc inputs. In this paper, the balancing mechanism and control parameter design of the proposed method are presented in detail. With the proposed strategy, the FCV can be controlled around half of the bus voltage with error less than 2%. Besides, a pre-charge strategy for flying capacitor is also provided in this paper. The performance and analysis of the proposed strategy are verified by the experiments at last.

The three-phase dual active bridge (3p-DAB) is a popular topology suitable for high power DC-DC isolated conversion. This converter features bi-directional power flow, zero-voltage switching capability, and reduced transformer and filter volume. These features meet the requirements of several applications, such as solid-state transformers. But when operating under light load the resulting converter efficiency is highly degraded by the loss of soft-switching capability. This paper introduces the use of a Wye-extended-Delta (Y-e) transformer winding in the 3p-DAB converter, which increases the efficiency under light load, keeping the simplicity of phase-shift control. The framework developed allows a complete analysis of the converter, including the determination of the power and rms current, zero-voltage switching boundaries and the impact of the selected phase-shifting angle in the transformer design. Additionally, this paper presents a negative sequence modulation scheme, allowing maximum efficiency under light loads to be achieved for both direct and reverse power flows. The performance of the 3p-DAB with Y-e transformers is compared with previously reported winding options for 3p-DAB. The experimental results show a converter efficiency increase, up to 10\% for direct power flow and up to 9\% for reverse power flow, when operating at light load (10\% of nominal power).

Automotive applications demand high efficiency, good reliability, and a wide operating speed range within limited DC bus voltage constraints. In this paper, a zero degree displacement dual three-phase PMSM is derived from an original 3-phase PMSM to enhance the power rating as well as the operating speed range. The proposed topology can be used as an alternative to the conventional configuration of three-phase PMSM with a bidirectional DC-DC converter for electric vehicles. Even though the commonly used dual three-phase PMSM with split-phase winding eliminates the sixth harmonic torque pulsation, a large circulating current is generated during six-step operation, which results in additional stator copper loss. In this paper, six-step operation of the symmetric dual three-phase PMSM with zero degree winding displacement is proposed to achieve maximum inverter utilisation. Both harmonic circulating current and torque pulsation were observed to be within satisfactory levels using this configuration. A changeover algorithm is also proposed to enable a smooth transition between closed-loop current vector control during low and medium speed operation to open-loop six-step voltage angle control for high speed operation. The performance of the proposed method is experimentally validated on a 3kW dual three-phase PMSM drive.

This paper presents a ground breaking traction drive for fuel cell powered light rail vehicles based on a multilevel cascade converter with H-bridge cells. The converter provides dc-ac power conversion with unique buck-boost capability to compensate for the variation of fuel cell terminal voltage with the load power. In comparison to a conventional boost inverter, based on the cascade connection of a boost dc-dc converter and a voltage source inverter, the proposed converter has the significant benefits of much smaller inductor size, lower dc side current ripple, and multilevel voltage waveforms at the ac output. This paper presents the converter modelling and design of the boost inductor and sub-module capacitors, taking into account the full speed range of the motor. The concept has been fully validated on a bespoke experimental prototype driving a small induction motor, showing the suitability of the proposed converter as a traction drive for hydrogen-powered rail vehicles.

Magnetic bearing is an important part of modern high-speed rotating machinery. The performance of power electronic converter highly determines the quality of magnetic bearing drive. In this paper, a fault-tolerant converter with series-winding topology is introduced. Compared with the traditional topology, the current stress of the phase leg is reduced while the utilization of DC voltage is guaranteed, and fault-tolerant operation can be realized in the case of open circuit fault of the switching device. This paper introduces the characteristics of the series-winding topology and the current control method. Open circuit fault detection methods and countermeasures are also analyzed. Experimental results show the effectiveness of the proposed topology. Fault-tolerant experiments under static suspension and rotation of the rotor demonstrate the performance of the topology. This kind of series-winding topology provides a new scheme with good performance and high reliability for the design of magnetic bearing controllers.

In this paper, an effective solution is presented for efficient robotic object search by leveraging metric-topological map. Based on the reference of objects, we construct a novel metric-topological map that is particularly suitable for object search, where the topological nodes represent the object-related locations in the environment. To effectively determine the creation of nodes on the map, a rapid adjustment method of the robot viewing angle is introduced. Compared with traditional maps, the map built in this paper not only removes redundant nodes irrelevant to objects, but also facilitates the mobile robot to locate the target object. Besides, inspired by human search behavior, a search strategy is proposed by considering the tradeoff between the current position of the robot and the distance from the robot to the promising location of finding the target object, in order to further improve the search efficiency. The effectiveness and efficiency of our solution is verified through comparative experiments in both simulation and real-world environments. Results show that the presented approach always allows the mobile robot to find the target object efficiently and reliably, while achieving human-like search behavior.

In this paper, a novel zero-voltage switching (ZVS) full-bridge converter is proposed to overcome the disadvantages of traditional phase-shifted full-bridge (PSFB) converter. In the proposed converter, a half-bridge (HB) converter with center-tap rectifier (CTR) is integrated into the traditional PSFB converter by sharing the lagging-leg switches and output filter. The HB converter operates with full duty cycle to ensure continuous energy transmission and the output voltage is regulated by adjusting the phase-shifted time of FB converter. The proposed converter has many advantages such as reduced filter requirement, wide ZVS range and low primary circulating current. In addition, the rectifier in the proposed converter is composed of a full-bridge rectifier (FBR) section and a CTR section. This feature makes the proposed converter well appropriate for the medium output voltage applications. Key operation principle and characteristics are fully discussed in this paper. The effectiveness of proposed converter is verified using a 1.2-kW prototype circuit with 280 V input voltage and 60-120 V output voltage.

On-line detection of rotor and load faults in permanent magnet synchronous motors (PMSM) based on spectrum analysis of current or vibration is not capable of identifying the root cause of the fault, since all faults produce identical fault signatures. The sensitivity of fault detection also depends on the motor and controller design making fault detection unreliable. In addition, operation under variable frequency and load limits the effectiveness of spectrum analysis based methods. In this paper, airgap flux monitoring is investigated as an alternative for providing reliable identification of rotor and load faults in PMSMs. Based on the analysis of airgap flux under partial and uniform demagnetization, dynamic eccentricity and load unbalance, an airgap search coil voltage based method for detection and classification of the faults is proposed. The claims made in the paper are verified through experimental testing on an IPMSM under emulated fault conditions along with a comparison to vibration and current spectra-based detection. It is shown that the proposed method provides reliable on-line identification of the faults for cases where conventional spectrum analysis based methods fail.

This paper proposes a coupled-inductor-based soft switching non-inverting Buck-Boost Converter (NIBBC) with reduced auxiliary component count. Instead of using multiple auxiliary passive components to achieve soft switching, the proposed coupled-inductor-based NIBBC uses the coupled inductor as the main inductor, and the auxiliary current generated by the magnetic coupling effect is used to obtain the soft switching for all switches. With simple PWM modulation under fixed frequency, full load range ZVS can be obtained under wide voltage range. Unlike the conventional method utilizing the coupled inductor only to generate non-active power, the coupled inductor of the proposed converter also takes participant in the power transmission. Besides, the added diode can achieve zero current turn-off which avoids the diode recovery issue. The operating principle, the soft switching and parameter designs are analyzed in this paper. Finally, experimental results have verified the effectiveness of the proposed solution.

Low-voltage multi-terminal DC system is one of the important forms in distribution network. Its stability issue has drawn worldwide attention for the characteristics of low inertia and weak damping. This paper aims to analyze the interactive behavior between the voltage source converter (VSC) and the oscillation mode of the DC network. First, this paper proposed a modeling method for DC voltage control loop considering the time-lag effect of inductor energy storage behavior on the AC side of the VSC. Based on this model, the interactive behavior between VSC and DC network including the influence of droop coefficients and load power under DC voltage-AC power (Vdc-Pac) droop control mode and under DC voltage-DC power (Vdc-Pdc) droop control mode is studied. Then, the overall state-space model of the system is established. Furthermore, the stability of a low-voltage three-terminal DC system under different control modes and parameters is compared and detailed analyzed. Finally, the corresponding simulation and experimental verification validate the theoretical analysis. The research results show that under the same capacity and control parameters, Vdc-Pac mode can better improve the capability of power regulation and system stability. This research can provide an effective method for system control modes design.

This paper focuses on the modeling and stability analysis of the typical single-phase phase-locked loop (PLL) based on second-order generalized integrator (SOGI). Traditionally, SOGI-based PLL (SOGI-PLL) is linearized as the linear time-invariant (LTI) model for the stability analysis and parameter design. Yet, the PLL has periodical nature due to the periodical variation of the grid voltage. The traditional LTI model for PLL thereby reduces the precision of stability analysis. For addressing this problem, an accurate linear time-periodic (LTP) model of the single-phase SOGI-PLL is proposed in this paper. The proposed model can precisely characterize the coupling nature of phase, frequency, and amplitude estimated by SOGI-PLL. A precise stability region of SOGI-PLL thereby can be derived from the proposed LTP model. The effectiveness of the proposed LTP model for SOGI-PLL is verified by simulation and experimental tests.

Railway power conditioner (RPC) can provide comprehensive reactive power, unbalanced current, and harmonics compensation in the traction power supply system (TPSS). Under full compensation (FC), RPC can increase the three-phase power factor (PF) to unity but leads to high current rating and operation loss. In previous studies, partial compensation (PC) for the reduction of RPC current rating was proposed. An analytical solution of partial compensation coefficients was used, which limits design freedom since identical PF is required at three-phase. This uniform power factor partial compensation (UPFPC) limits RPC in achieving a further reduction in its current rating. This paper proposes a nonuniform power factor partial compensation (NPFPC), which can further reduce RPC current rating within the acceptable power factor region and under the voltage unbalance threshold. However, determining an analytical solution under NPFPC is complicated, considering three degrees of freedom. This is achieved so in this paper by defining the lower boundary of grid side PFs and optimizing by particle swarm optimization (PSO). It is found through investigations that NPFPC can effectively reduce the compensating current rating by 56% compared to FC mode and 53% compared to UPFPC. Simulation and experimental results verify the validity of the proposed NPFPC.

Different from the typical topology derivation of power electronics converters (PECs) depending on manual effort, this paper aims to explore a programmable method based on graph theory for multi-port dc-dc converters with reduced switches. By mathematically modelling converters with graph theory and transforming their working criterions into the corresponding graph constraints, the topology derivation can be automatically and conveniently solved with the aid of computer program. In the paper, principle of the proposed graph theory based programmable method is firstly introduced in detail. Then, it is employed to derive multi-port dc-dc converters with reduced switches and a diversity of new topologies are simultaneously excavated, among which a favorable one is selected to be theoretically introduced and experimentally verified. The proposed method remains relatively simple with the increasing number of ports, as the graph constraints of working criterions are almost the same for different number of ports. More importantly, because PECs can be essentially regarded as graphs with different components and their connecting relationships, the proposed method is applicable for many various converters.

In this paper, two novel approaches for identifying the synchronous generator (SG) parameters are presented. The proposed approaches use an experimentally obtained armature current during the short-circuit test as input data. Both approaches are simple, cost-effective, and practical since they do not require any additional equipment for signal generation nor applying any of the advanced control techniques. The first approach relies on fitting the analytical total armature current waveform with the experimental one, while the second approach relies on matching the observed waveform with an analytical waveform of asymmetrical and alternating components. Instead of traditional graphical methods typically used in standardized procedures, this paper also proposes a novel hybrid metaheuristic algorithm to identify the SGs parameters. The experimental verification of the proposed methods is carried out on 100 MVA SG at the Bajina Basta hydropower plant (HPP) in Serbia.

The performance of fault diagnosis and prognosis (FDP) relies greatly on the model that describes the fault behavior and dynamics under study. In the past decades, many researches focused on establishing reliable, robust, and accurate models to describe fault growth dynamics. However, uncertainties in modelling process severely affect the accuracy and precision of FDP results. A major challenge in FDP is how to deal with the uncertainties that affect the performance of the system. For commonly used state space model, uncertainties exist in both the state transition equation and the measurement equation. In this paper, the influence of uncertainties on FDP results are studied and compared in terms of accuracy and precision. Furthermore, this paper proposes a differential model decomposition approach, which can automatically acquire appropriate model parameters and uncertainties for state space model. The effectiveness and advantages of the proposed method are verified and demonstrated with three different application scenarios, including comparison studies on public data and online experimental verification.

In this paper, we propose the dynamic coverage control method based on K-means. In the traditional coverage control, Voronoi partition method is used to assign the coverage positions for intelligent units. However, the Voronoi partition method requires that the space to be covered is compact and convex, and it is difficult to realize the coverage control of high-dimensional space. Therefore, in this paper we propose a dynamic coverage planning algorithm based on K-means, which relaxes the requirements on the coverage objects and can calculate the optimal coverage positions of the intelligent units. In addition, we also design a dynamic coverage control law based on discrete sliding mode control to drive the intelligent units to the optimal coverage positions. Through the combination of planning algorithm and control law, the optimal coverage control performance can be achieved for the specified targets and the specified area, which can be discrete, non-convex and high-dimensional. The stability of the planning algorithm and the control law are proved by theoretical deduction. And the effectiveness and superiority of the dynamic coverage control method are verified by two examples.

This paper analyzes the conventional dq-frame model-based deadbeat predictive current control (DBPCC) methods for high-speed permanent magnet synchronous machine (PMSM) drives with low switchingtofundamental frequency ratios (SFRs). It shows that the state-of-the-art compensation schemes of control delay and rotor movement effect can improve the control performance but the problem would still arise at very high speeds with very low SFRs. Therefore, this paper presents a novel DBPCC method for high-speed PMSM drives. The proposed method tracks the machine stator flux vector in the stationary frame to achieve deadbeat control of the dq-axis currents. The control delay and rotor movement effect are both precisely considered. Consequently, the control performance and stability of the proposed DBPCC can be guaranteed at high speeds. Extensive simulations and experiments have been performed on a prototype high-speed PMSM drive. The effectiveness of the proposed method and its superiorities against the field-oriented control (FOC) and the conventional DBPCCs have all been demonstrated.

This paper proposes and implements an output-controllable efficiency-optimized wireless power transfer scheme using hybrid modulation. The key is to combine pulse frequency modulation (PFM) and on-off keying (OOK) modulation and to utilize feedback control. Among them, PFM is used for the output voltage regulation of the inverter to adjust the rectified output voltage on the receiver side, while OOK modulation is adopted to convert the load resistance to be close to the optimal resistance value so that the system efficiency can be effectively optimized. When the relationship between the input and output voltages reaches a ratio related to system parameters, it can be considered that the load resistance has reached the optimal state. Hence, the feedback output voltage is utilized to help convert the load resistance into an optimal value and only one voltage acquisition circuit is needed. In this paper, theoretical analysis and practical experimentation (using the LED lamp as a nonlinear load and the 102- resistance as a linear load) are both given to verify that the proposed scheme can help to maintain high system efficiency during the output voltage regulation process.

In this paper, we investigate a novel multi-sensor odor detection system (electronic nose) for low concentration volatile organic compounds (VOCs). In order to break through the limitation for detecting low concentration volatile organic compounds, we design a conformal symmetric pre-concentration unit structure based on the finite element method. A typical application for exhaled breath is developed to investigate the proposed scheme. The designed pre-concentration system can increase the concentration of the concentrated substance, so that the sensor can detect it. Besides, we choose the alveolar gas at the bottom of the human lung, which can better represent the health status of the human body, to carry out the effectiveness test of the system. In order to combine the gas acquisition system with the pre-concentration system, this paper further designs a cost-effective alveolar gas collection device by a doubled adaptive Pulse Width Modulation (PWM) operation. Finally, the effectiveness of the pre-concentration system is judged by the detection results of gas chromatography-mass spectrometry (GC-MS). We also use the classical algorithm to classify lung cancer and non-lung cancer patients, which proves the effectiveness of our proposed integrated design system and shows the potential of practical application of the system.

This paper analyzes the effect of discretization in the frequency-adaptive flux observer (FAO). Although FAO has structural simplicity and ease of implementation, the discrete-time FAO has phase and gain errors in fundamental flux estimation. As a result, the estimated flux might be erroneous, especially in the high-speed region. For accurate flux estimation, this paper analyzes how the voltage synthesis in the pulse-width-modulation (PWM) affects the stator flux. Through the analysis, the backward Euler method is selected for the primitive stator flux estimation. To mitigate the FAOs discretization error, the proposed FAO utilizes the integrators constructed at the rotor reference frame. Since the discretization error comes from the approximation error of the continuous-time integrator at the operating frequency, the proposed FAO conducts the fundamental flux extraction at the rotor reference frame, where the operating frequency components are treated as a dc signal. Thanks to the coordinate transformation, the FAO can be discretized with no error while keeping the structure of double integrators. The proposed method is verified through the computer simulation and experimental test.

This paper proposes a new combination of correlative statistical analysis and the sliding window technique to detect incipient faults. Compared with the existing monitoring methods based on principal component analysis and transformed component analysis, the combination fully uses the information from the process and quality variables. The sliding window, however, inevitably increases the computation burden due to the repeated window calculations. Therefore, a recursive algorithm is proposed in this paper, which has been shown to have less calculation complexity. Furthermore, a randomized algorithm is proposed to determine the width of sliding window. A numerical example and the thermal power plant process are presented to show the effectiveness and advantages of the proposed method.

In this paper, a nite-time trajectory tracking control problem is studied for a rodless pneumatic cylinder system with disturbance in an inner-outer loop framework. In the inner loop system, the generalized nonlinear extended state observer and the inner-loop controller are designed to estimate and compensate the matched disturbances, respectively. The generalized nonlinear extended state observer designed in this paper achieves desired convergence performance under relaxed existence conditions. In the outer-loop system, a super-twisting extended state observer and an outer loop controller are designed to estimate and compensate the unmatched disturbances, respectively. The super-twisting extended state observer is designed to realize nite-time stable by using the super-twisting technology. Finally, experiment results are shown that finite-time control performances are obtained by the proposed control strategy.

The security of data propagation is a critical challenge for the widespread use of networked control systems (NCSs), while the conventional strategies based on estimation techniques cannot solve this issue well. Furthermore, the contradiction between the security and real-time nature of the control method has not been settled yet. The aim of this paper is to propose a novel real-time control method empowered by blockchain technologies to resolve the security problems of NCSs under potential cyberattack. To facilitate the analysis of blockchain-assisted NCSs, a cyber-authentic-physical system (CAPS) framework is proposed. One of the significant features of CAPS is that the defense of NCSs against attacks is built by introducing a blockchain protocol. Theoretical analysis reveals the relationship among the scale of the peer-to-peer (P2P) network, the security of CAPS, and the latency of NCSs, as well as clarifies the impact of the introduction of blockchain mechanism on the performance of NCSs. With the networked secure control mechanism designed in this paper, the security and stability of NCSs can be achieved simultaneously, and sufficient conditions of which are also given. Finally, simulations and practical experiments are presented to show the efficacy of the suggested secure control strategy.

LLC half-bridge converters have been extensively studied in low power industrial applications. However, the phase shift angle between the voltage and current of the LLC resonant network makes the converter have power circulation, that is, backflow power. The increase of the backflow power will increase the converter conduction loss, which restricts the improvement of the converter efficiency. The existing literature often improves the backflow power from the control aspect, which greatly increases the control complexity. To solve this problem, this paper proposes an LLC half-bridge resonant converter analysis method that takes the backflow power into account. Based on the analysis of operating mode and AC equivalent model of the converter, backflow power is indirectly characterized by the phase-shift angle of the resonant network voltage and current. Based on this, this paper analyzes the internal relationship between resonant parameters and backflow power to reduce backflow power by optimizing resonant parameters. Under the setting operating conditions, converter can achieve ZVS switching, voltage gain conditions and minimum backflow power. Compared with the existing methods, the proposed optimization method avoids additional auxiliary circuits and control complexity, improves the stability of the circuit. Experimental results verify the accuracy and feasibility of the theoretical analysis.

This paper presents an improved current reconstruction technique with current prediction for a permanent magnet synchronous motor (PMSM) drive system. In some conventional single current sensor (SCS) techniques, current fluctuations occur at sector switching period (SSP) due to current holding between two adjacent sampling interval, which can cause current distortion and introduce much current harmonics especially when the motor speed is very high. Focusing on that, a current prediction method is proposed in this paper to prevent the current fluctuation happening at SSP. The SSP is divided into two independent parts for the accurate calculation of output voltage vector and actual three-phase currents at SSP are determined on account of both the predicted dq-axis currents and the measurable ones. As a result, compared with previous current holding strategy, the current fluctuations can be fundamentally eliminated under the proposed method with less current harmonics introduced, further improving the control performance of the whole system. The accuracy and practicability of the proposed method is verified by experimental results.

This paper presents a novel concept of switch-mode DC-DC boost converters with reduced switching losses. The converters use an auxiliary switching cell (ASC) to achieve zero voltage switching (ZVS) during the turn-off of a transistor. The novel concept facilitates an increase in the efficiency or switching frequency of an IGBT-based boost converter. The paper discusses the converters topology, the principle of operation, and issues related to the reduction of power losses, the range of optimal operation and selection of components. The concept of the converter was verified through simulation and a series of experiments that demonstrate the process of zero-voltage turn-off and the efficiency of the converter.

Conventional ultrasound probes have inherent limitations in some application scenarios. Because of their fixed shapes and sizes, they can hardly pass through small orifices to examine the target closely. With the recent development of micro-electro-mechanical systems (MEMS) and flexible electronic technologies, collapsible and self-assembling devices are being considered as a potential approach to address this problem. This paper presents an innovative transformable ultrasonic transducer (TUT), which can transform between a 1D linear array and a 2D planar array with the ability of switching between different functions including 2D/3D imaging and high-intensity focused ultrasound beamforming. The transforming process is accomplished with a specially designed flexible printed circuit board inspired by paper-folding mechanism. The electrical and acoustic properties of the developed transducer along with the acoustic field distribution in its different forms have been characterized. The 2D/3D imaging performances of the TUT have been also evaluated under 1D and 2D configurations, respectively. In addition, the performance of a focused concave transforming mode has been also discussed. The evaluation results suggest that TUT can maintain its performance under different structures with precise transforming control. The TUT device has the potential to considerably expand the applications of industrial and clinical ultrasound.

The design and analysis of megawatt power electronics systems calls for an accurate and efficient simulation approach that can consider the switching transients. However, the state-of-the-art simulation methods and tools exhibit low efficiency in megawatt power electronics systems, even with ideal switch model. It is hardly possible to perform physical-switch-model-based simulation due to the time cost and the convergence issue. This paper proposes a switching transient simulation approach based on the discrete state event-driven approach. The proposed method is composed of a switch-pair-based modeling method and a time-scale-decoupling simulation method. In the example of a 2 MW power electronics transformer composed of 576 semiconductor switches, the proposed method enables the switching transient simulation of a 0.2-second dynamic within 10 minutes and is free of convergence problems. The speed is 20-fold faster than commercial software adopting ideal switch model. The accuracy is attested to by comparisons with both experimental and commercial software results. Meanwhile, this paper demonstrates the application in system efficiency evaluation. Due to the speed gain and the ability of capturing switching transients, the proposed method enables simulation of the efficiency curve, and hence the locating of the maximum efficiency point and optimized design of the conversion system.

In the sensorless control system of an induction machine, the rotor speed value is not measured but reconstructed by an observer structure. The rotor speed value can be reconstructed by the classical adaptive law with the integrator. The second approach, which is the main contribution of this paper, is the non-adaptive structure without an integrator. The proposed method of the rotor speed reconstruction is based on an algebraic relationship – the rank of the mathematical model of the observer system is not increased. However, the problem with the stabilization of the observer structure does exist. For near to zero rotor speed or in the regenerating mode of an induction machine, the speed observer structure can be unstable. Therefore, in this paper, the new stabilization functions are proposed. The stability is provided by the Lyapunov theorem and the practical stability theorems in which the uncertainty of parameters is considered. In the proposed solution, the newly introduced stabilization functions guarantee observer stability during both the motoring and regenerating conditions at the chosen low rotor speed ranges and for different load torque values. All the theoretical considerations were confirmed by simulation and experimental tests during the chosen working modes and uncertainties of nominal parameters of the induction machine.

In this paper, a Phase-shift-modulated (PS) Resonant Two-switch Boosting Switched-capacitor Converter (RTBSC) and its modulation map are proposed. Compared with the traditional RTBSC, all diodes are replaced by active switches and then phase-shift modulation is applied. The advantages of the modified topology are obtained as follow. 1) The voltage gain can be regulated efficiently either below or above the nominal value even at light-load condition, making it suitable for applications with voltage fluctuations; 2) The conduction loss is reduced by replacing all diodes in RTBSC with low turn-on resistance transistors, especially for high-order and high-gain configuration; 3) All switches achieve the zero-voltage-switching (ZVS) turn-on operation; 4) The soft-charging property smooths the current profile. Aside from the topology modification, a comprehensive analysis of operation principle, voltage gain, component stress and ZVS region is given. On the basis, a modulation map with the optimal operation region is proposed. It provides a guideline to operate and design such converters in the target gain range, low component stress and ZVS region, making up for the lack of modulation map and design guideline in aforementioned literatures. A 120W prototype with low-voltage side 43-60V and high-voltage side 150V was designed to verify the above analyses.

Mission profile emulation for submodules (SMs) in the modular multilevel converter (MMC) is a crucial step before a full-scale system is put into field operation. Existing methods suffer from limitations of the testing accuracy due to the staircase-like arm voltages which result in distorted loading current and require large filter inductance. This is especially the case when limited number of SMs are under test. In this paper, an efficient MPE method is proposed to emulate the loading behaviors of multiple SMs in MMC. The testing circuit allows two arms of MMC with flexible SM number, operating in inverting and rectifying mode under nearest level modulation (NLM), to be tested simultaneously with reduced DC supply voltage. A common H-bridge circuit is introduced in the testing circuit, with each arm of the H-bridge circuit functioning as the voltage compensator by using feed-forward control. In this way, the current distortion can be significantly suppressed and testing accuracy can be guaranteed in a cost-efficient manner even though no large inductor is included in the testing circuit. The proposed method allows SMs under test to be loaded as in the actual back-to-back MMC system. Simulations and experimental measurements are given to validate the proposed method.

DC microgrid as a micro-scale power system, has drawn growing attention for its various applications which calls for good power quality, proper power sharing, and fast response property. However, the existing researches aren't yet able to achieve the purpose in a predefined time. In this paper, a new predefined-time secondary controller is proposed for DC microgrid to realize the objectives of both voltage regulation and current sharing among distributed generators within a predefined time. The controller is designed by employing a sign function and a $K^1$ function and by defining a new composite error, which does not need to sample the voltage of DC bus or the current of neighbors, but only the local current and voltage. The upper bound of the convergence time of both the voltage and current in the DC microgrid is just related to one parameter which can be predefined and is independent of initial error. The effectiveness of the proposed controller is verified by multiple simulations and experiments built on MATLAB/Simulink and a hardware-in-the-loop experimental platform. The conducted simulations and experiments include several typical scenarios together with a comparison, which illustrate the advantages of the proposed controller such as fast convergence rate and small overshoot.

In this paper, a fault-tolerant model-free predictive controller (FT-MFPC) for cascaded H-bridge multilevel inverters (CHMLIs) is proposed. FT-MFPC is based on an association of model-free predictive controller (MFPC) and a PI-like structure known as current variation controller (CVC). As in MFPC, the dynamic structure (DS) which is used for prediction of the system output is obtained from past measurements of current variations, but CVC modifies the dynamics before they are stored for prediction. As a consequence, even if the converter operates with bypassed modules, FT-MFPC adapts its DS to represent the real dynamics of the system and enables a closed-loop response with balanced load currents in unbalanced CHMLIs. Simulation and experimental results validate the adaptability of the proposed strategy to operate a seven-level inverter under various configurations of bypassed H-bridge modules. The experimental results show that, for different post-fault operations, the maximal current THD and imbalance factor at steady state in the worst-case scenario are below 5% and 2%, respectively.

In this paper, a novel method is proposed to design a hybrid network (HN) to increase isolation and shape radiation patterns for multiple-input multiple-output (MIMO) antenna systems. The HN is a combination of a decoupling feeding network (DFN) and a defected ground network (DGN), which are populated by several surface-mounted reactive components whose reactances are determined by the N-ary optimization algorithm. Two decoupling examples are presented to validate the design methodology and elaborate on the design procedure. Measurement results show that the HN helps to realize impedance matching with reflection coefficients below -10 dB, isolation improvement from -5.4 dB/-8.9 dB to below -20 dB, and low envelope correlation coefficient below 0.06 for MIMO antennas with the element separation of 0.160/0.240. Moreover, in both examples, the decoupling case with omnidirectional radiation patterns achieves a better throughput performance, compared with another decoupling case with directional radiation. In comparison to prior decoupling networks only focusing on isolation enhancement, the proposed HN achieves high isolation and desired radiation patterns simultaneously with a very accurate design methodology.

The paper proposes a new Vector Analysis based Model Predictive Control (VAMPC) method for multilevel converters with four different switching configurations. It is based on track of an error vector using fundamental state vectors, and can achieve deadbeat control of four switching states multilevel converters with multiple control objectives. Compared with conventional finite control set model predictive control (FCS-MPC) method, VAMPC can achieve excellent spectrum characteristics in the case of a slight increase in computational burden. The VAMPC method is experimentally validated on a 100 kHz GaN-based 3-level flying capacitor (FC) converter. Compared with the FCS-MPC, VAMPC leads to significant reduction in steady-state control errors. For example, the inductor current total harmonic distortion (THD) of the FC converter is now reduced by more than 60%.

Space vector modulation (SVM) is a mature modulation scheme, which is widely used for voltage sourced inverters. In this paper, a flexible online SVM scheme is proposed for a cascaded H-bridge multilevel inverter (CHMI) under short-circuit and open-circuit switch as well as cell failure conditions. The proposed scheme directly calculates all the active redundant switching states and the dwelling duty cycles of the three space vectors enclosing the reference vector for a CHMI such that balanced line-to-line voltages and currents under failure conditions are generated. Accordingly, the resultant switching sequences are determined to meet any specific requirement, e.g., even-order harmonics elimination and minimization of switching losses. Furthermore, in order to reduce voltage stress on the semiconductors under short- and open-circuit switch conditions, an equal power distribution criterion is introduced. The proposed SVM scheme is fast and independent of the number of levels. Experimental results are presented to demonstrate performance and effectiveness of the proposed scheme.

The safety and energy efficiency of autonomous vehicles in the vehicle-following driving scenario is seriously affected by the decision-making framework. This paper proposes a safe and energy-saving decision-making framework for autonomous vehicles to avoid the potential rear-end collision and improve the energy efficiency in vehicle-following driving scenario. To realize this framework, the vehicle longitudinal dynamics model is first presented, and the autonomous vehicles requirements from the safety and energy efficiency perspectives are comprehensively analyzed in the vehicle-following driving scenario. Then, a two-stage decision-making framework is designed. The first stage determines the safety region in the powertrain control domain, and the second stage determines the optimal energy efficiency in the safety region. Based on the two-stage decision-making framework, the perspective of safety first principle can be enforced by simultaneously considering the driving safety and energy efficiency. Finally, the experiment is conducted to demon-strate the advantages of the proposed method by com-paring it with two other state-of-art methods.