Search Results (791)

An adaptive super-twisting algorithm (ASTA)-based variable-damping strategy coordinated with five-vector model predictive current control (FV-MPCC) is proposed for a dual three-phase permanent magnet linear generator (DTP-PMLG) wave energy conversion system. In the upper-level controller, the power take-off (PTO) damping coefficient is adjusted online based on the captured power gradient, and finite-time convergence of the power-gradient variable is established via Lyapunov analysis. In the lower-level controller, four active voltage vectors and one zero voltage vector are applied in each sampling period, so that the d–q–x–y current components are directly included in the action-time calculation. Therefore, q-axis current tracking and x–y harmonic-current suppression are achieved simultaneously. Simulation results under two irregular-wave conditions show that the proposed variable-damping law approaches the optimal fixed-damping performance without requiring prior sea-state-specific damping selection, increasing the mean captured power by 2.38% and 3.44% relative to the optimal fixed-damping cases. Experimental results further confirm that the proposed FV-MPCC reduces the d-axis and q-axis current ripples by 35.92% and 40.66%, respectively, compared with conventional MPCC. Full article

Transimpedance amplifiers (TIAs) are the critical components for current-to-voltage interfaces in optical receivers, LiDAR front-ends, biomedical sensors, and unconventional applications such as magnetic-resonance receiver-coil arrays and wide-bandgap ultraviolet detectors, and their CMOS design is governed by a fundamental gain-bandwidth-noise trade-off whose structure is rarely made explicit. This review introduces a unifying framework rooted in three explicit assumptions underlying the classical shunt-feedback TIA limit: a single-pole core amplifier (A1), a resistive feedback element (A2), and the full input capacitance loading the feedback summing node (A3). Relaxing one or more of these assumptions is shown to be the common structural thread behind every class of bandwidth or noise enhancement in the recent literature, and all surveyed architectures are organized into a six-tier taxonomy, from Tier 0 designs operating within the classical limit to Tier 5 topologies that bypass all three assumptions simultaneously. This taxonomy is supplemented by an orthogonal configurability axis spanning single- and dual-control reconfigurable, variable-gain, and dynamic-range-extension designs. We further show that stability is not removed by these relaxations but migrates with the tier, from the global phase margin of the classical loop to a local regulating loop, a group-delay-flatness constraint, an input-passivity condition, or a multi-loop interaction, so that each architecture carries a predictable stability locus. The taxonomy is cross-referenced with application domains and closed-form noise-floor boundary plots parametrized by input capacitance and amplifier gain-bandwidth product, and with the CMOS technology landscape, where we argue that the most advanced node is not universally optimal and that node and topology act as complementary rather than competing levers. A single consistent figure of merit, applied uniformly to a representative set of CMOS realizations from 0.6 $\mathsf{\mu }$m to 16 nm FinFET, shows no monotonic improvement with publication year or node and is presented as a diagnostic indicator rather than an absolute ranking. The review closes with an outlook on 200 Gb/s/lane links, wide-bandgap sensor integration, and the FinFET-to-gate-all-around device transition. Full article

With the rapid development of DC grids, resonant DC circuit breakers (RDCBs) have become critical for fault isolation. However, existing RDCBs often suffer from severe energy mismatches, and components, including mechanical switches, resonant capacitors, and power electronic devices, suffer from excessive internal overvoltage during the current interruption process. To address these issues, a novel RDCB with a capacitor self-charging current excitation source (CES) is proposed in this paper. First, by controlling the charging process of CES by the fault current, the injected energy is matched with the commutation requirements, significantly reducing the transient recovery voltage (TRV) applied to the mechanical switch. Second, to suppress the voltage applied to the resonant capacitor, a metal oxide arrestor (MOA) should be connected directly in parallel with the resonant capacitor, avoiding overvoltage caused by the internal oscillation between the resonant inductance and the resonant capacitor. Furthermore, an anti-parallel magnetic core is designed for CES, ensuring dynamic current sharing among parallel IGBTs while maintaining a zero-inductance characteristic externally. Simulation results verify that the proposed RDCB reduces the peak TRV by at least 64% compared with existing RDCBs. Furthermore, the effectiveness of the proposed overvoltage suppression methods is validated, significantly improving the interrupting reliability. Full article

Linear transformer drivers (LTDs) offer significant advantages for pulsed power applications, but solid-state implementations typically rely on MOSFETs or IGBTs that impose current handling limitations. Thyristors provide substantially higher current handling capability compared to other solid-state switches, making them highly attractive for high-current pulsed-power LTDs. However, because they cannot be turned off through gate control, conventional pulse-width modulation is not possible, limiting their use in applications that require tunable pulse durations. This paper presents a method for achieving pulse width control in thyristor-switched LTDs by exploiting controlled magnetic core saturation. By varying the magnetic reset applied to the cores prior to discharge, the available flux swing and the resulting output pulse duration can be precisely controlled. A 10-stage thyristor-switched LTD was designed and constructed to validate this approach, utilizing SP245-03 thyristors and nanocrystalline magnetic cores. The results demonstrate continuous pulse width control from 540 ns to 1.7 µs at nominal 10 kV output voltage, with the output pulse duration exhibiting a linear relationship with applied reset time up to core saturation. The measured maximum pulse width agrees well with theoretical predictions based on Faraday’s law. This work demonstrates that thyristor-based LTDs can achieve flexible pulse width modulation while benefiting from the higher current ratings these devices offer, enabling new design possibilities for high-current pulsed power systems. Full article

Assessment of left atrial remodeling in atrial fibrillation (AF) has traditionally relied on anteroposterior diameter, left atrial volume (LAV), and indexed left atrial volume (LAVI). Although these measures remain clinically useful, they reduce a complex, asymmetric, and anatomically constrained chamber to scalar descriptors and therefore cannot fully capture the spatial substrate that underlies AF persistence, thromboembolic risk, or arrhythmia recurrence after catheter ablation. Three-dimensional left atrial reconstruction provides a more refined framework by preserving chamber shape, regional deformation, pulmonary vein (PV) orientation, left atrial appendage (LAA) geometry, posterior wall and roof configuration, left lateral ridge anatomy, wall-thickness heterogeneity, and computational surface features. In this review, we examine how three-dimensional left atrial geometry can extend conventional remodeling assessment from measurement of atrial size toward imaging-based substrate characterization. We discuss the relative strengths and limitations of computed tomography (CT), cardiovascular magnetic resonance (CMR), three-dimensional echocardiography, and electroanatomic mapping (EAM), and summarize key geometry-derived metrics, including LAV, LAVI, left atrial sphericity, asymmetry index, atrial eccentricity index, PV anatomy, LAA morphology, posterior wall geometry, wall thickness, radiomics, and artificial intelligence (AI)-derived shape descriptors. We further synthesize evidence linking geometric remodeling with atrial cardiomyopathy, mechanical dysfunction, fibrosis, low-voltage substrate, and catheter ablation outcomes. The clinical relevance of three-dimensional left atrial geometry may be further redefined by pulsed field ablation (PFA), whose non-thermal lesion biology and tissue selectivity may modify predictors of recurrence established in radiofrequency and cryoballoon cohorts. Finally, we outline the need for standardized segmentation, harmonized metric definitions, prospective multicenter validation, and integration with AI, digital twin modeling, biomarkers, EAM data, and wearable-derived AF burden. Three-dimensional left atrial geometry is not yet a standalone determinant of ablation strategy, but it may become a central component of individualized atrial phenotyping and rhythm-control decision-making. Full article

Wireless power transfer (WPT) technology offers reliability, safety, and ease of use for low-power charging applications. However, output regulation is difficult when the secondary side is inaccessible, because the magnetic coupling factor $k$ and the equivalent load resistance $R_L$may both be unknown and variable. This work addresses the two unknown parameters problem using only primary-side measurements of the DC-link voltage $V_{DC}$and the primary resonant current $I_1$. An initial calibration stage temporarily connects a known resistance on the receiver side, making it possible to estimate $k$ without a secondary-to-primary communication link. Then, during the charging stage, the previously estimated coupling is used to estimate the equivalent load resistance and to indirectly regulate the charger input voltage through a primary-side pre-regulator. The proposed system is intended for low-power WPT chargers, in which the receiver side must be simple and compact. A resonant DC converter prototype was experimentally implemented using a Class-E inverter, a Series-Series compensation network, a full-bridge rectifier, primary-side voltage/current sensing, and a pre-regulator. The experimental results show a maximum coupling identification error of 3.9% and a maximum load-resistance identification error of 10.67%. The resulting output voltage is not measured directly at the load; instead, it is estimated from primary-side variables and maintained within the 4–6 V input window of the target charger around a 5 V reference, with a maximum relative voltage error of approximately 10%. The work therefore presents a primary-side identification and control proof of concept without secondary-to-primary communication, while explicitly discussing the calibration requirement, equivalent-load validation, efficiency limitations, and the conditions under which recalibration would be required. Full article

The permanent magnet synchronous linear motor (PMSLM) is a key technology for the ultra-high-speed acceleration in maglev transport systems over short distances. It has attracted significant research interest owing to its high power density, high efficiency, and excellent control performance. Nevertheless, the design of such motors faces several challenges. These include the accurate calculation of inductance parameters and the achievement of high thrust force density. To overcome these issues, this study first derives analytical expressions for per-unit-length inductance and thrust force. Based on these, key electromagnetic parameters and structural parameters of the motor are designed. A segmented design scheme is also proposed. A finite element model of a bilateral long-stator PMSLM is then established using Ansys Maxwell. Simulations are performed to analyze the motor’s back electromotive force (EMF), electromagnetic thrust force, inductance distribution, and induced voltage. The results show a good agreement between the simulation and theory. The error in inductance calculations ranges from −5.5% to +6.65%. The absolute error between the calculated and simulated thrust force values is below 0.8 kN. Furthermore, the non-uniformity in inductance distribution and the causes of thrust force fluctuation are investigated. Odd-order harmonics, such as the third and fifth, are identified in the induced voltage. This research offers a design methodology and simulation verification for ultra-high-speed PMSLMs. It lays a foundation for the future development of end-effect compensation and harmonic suppression strategies. Full article

Stator winding reconfiguration technology has attracted increasing attention because it can modify the torque–speed output characteristics of motors online and extend the high-efficiency operating region. However, conventional winding switching methods suffer from several limitations, including long transient duration, typically at the millisecond level; difficulty in precise control; current interruption or asymmetric operation during the transient process; and the resulting torque loss and torque fluctuation. To address these issues, this paper first proposes a seamless winding switching method. The core idea is to complete the switching within the zero-vector interval of a single SVPWM period, thereby eliminating potential surge voltage without requiring a snubber circuit. The proposed method reduces the transient duration to only 5 μs, eliminates current interruption and current asymmetry, and suppresses the associated torque ripple. Furthermore, a deadbeat predictive control strategy is employed. By directly controlling the voltage vector, the proposed strategy enables fast and accurate current tracking within one sampling period after reconfiguration, thereby avoiding current overshoot, oscillation, and the corresponding torque and speed fluctuations. In addition, a voltage feedforward compensation method is proposed to pre-compensate the voltage applied during the PWM period in which the winding reconfiguration is performed, thereby preventing the application of voltage vectors that are inconsistent with the actual motor winding connection. With these three innovative measures, fast, smooth, and robust winding reconfiguration is achieved. The mechanisms and implementation procedures of the proposed strategies are described in detail, and their feasibility and effectiveness are verified through experiments. Full article

Outer rotor permanent magnet synchronous motors (OPMSMs) are widely preferred in applications requiring high torque at low speeds due to their structural advantages. This study presents a co-simulation-based field-oriented control (FOC) of an OPMSM using ANSYS Maxwell, Twin Builder, and MATLAB/Simulink environments. The motor is modeled using the finite element method in ANSYS Maxwell, while the power electronics and control system are integrated through a co-simulation framework, enabling a realistic and high-fidelity analysis. The main objective of this study is to comparatively evaluate sinusoidal pulse width modulation (SPWM) and space vector pulse width modulation (SVPWM) techniques within the same control framework. To enhance the effectiveness and reliability of the FOC controller, a genetic algorithm (GA)-based optimization is employed to tune both conventional PI and fractional-order PI controllers in the speed control loop for the SVPWM method. The findings clearly show that SVPWM beats SPWM in all measured parameters, including current THD, DC-link voltage usage, and torque ripple, which is consistent with the well-known theoretical advantages stated in the literature. Furthermore, the GA-optimized fractional-order PI controller outperforms standard PI controllers in terms of overshoot, settling time, and torque ripple. Overall, the suggested co-simulation framework provides an effective platform for comparing modulation strategies, as well as illustrating the role of GA-tuned controllers in high-performance OPMSM drive systems. Full article

This study proposes an integrated self-aligning-torque energy recovery and DC-bus voltage stabilization strategy for a permanent-magnet synchronous motor (PMSM)-driven steer-by-wire system in new energy vehicles. During the front-wheel return-to-center process, self-aligning torque may provide excess mechanical energy to the steering actuator. Instead of dissipating this energy through a braking resistor, the proposed strategy converts part of the self-aligning-torque-induced mechanical energy into electrical energy and feeds it back to the low-voltage DC bus. To avoid ambiguity in the operating-mode description, this paper distinguishes the standard PMSM torque–speed quadrants from the mechanical stages of the steering process. Regenerative operation is defined according to the condition ($T_e{\omega }_m<0$), corresponding to the second or fourth quadrant of the PMSM torque–speed plane, whereas the return-to-center regenerative stage refers to the self-aligning-torque-dominated stage of the steer-by-wire motion. Based on this definition, an electromechanical energy-flow model is established to describe the transfer path from self-aligning torque to the PMSM and then to the DC bus. Considering that regenerative energy injection may cause DC-bus voltage fluctuation or braking-resistor activation, a single-loop bus-voltage stabilization method based on active disturbance rejection control is developed. A third-order linear extended state observer is adopted to estimate the lumped disturbance caused by self-aligning-torque variation, current coupling, load variation, parameter uncertainty, and inverter loss. The observer bandwidth, controller gains, current limitation, and overvoltage protection mechanisms are further discussed to improve the practical implementability of the proposed control strategy. In addition, an energy-accounting method is introduced to distinguish total steering energy consumption, available self-aligning-torque mechanical energy, gross recovered electrical energy, system losses, net recovered energy, and recovery efficiency. Simulation and experimental results show that the proposed strategy can suppress DC-bus voltage rise, reduce braking-resistor energy dissipation, and achieve measurable steering-actuator-level energy recovery during repeated return-to-center maneuvers. The results verify the feasibility of using self-aligning-torque-induced regenerative energy in PMSM-driven steer-by-wire systems, while the actual vehicle-level energy benefit depends on the driving cycle, low-voltage load demand, battery charging acceptance, and converter efficiency. Full article

Voltage control of magnetic anisotropy in nanoscale heterostructures plays a pivotal role in the design and realization of magnetic random-access memories. To achieve low-voltage operation with high reversibility, we introduce an ion-conducting TiO₂ layer capable of storing lithium ions atop a Ta/Pt/CoNi heterostructure. During the discharging process, lithium ions migrate into the TiO₂ layer. The resulting interfacial electric field between TiO₂ and CoNi induces a reversible evolution of magnetic anisotropy from the out-of-plane direction toward the in-plane direction. Within a voltage window of 1.5 V (from 3.0 V to 1.5 V), both remanent magnetization and coercivity are suppressed to zero. Furthermore, consecutive charge–discharge cycles indicate the reversibility in the modulation of remanent magnetization and coercivity. These findings highlight that ion migration at the magnetic interface enables efficient and reversible control of magnetic anisotropy, opening new opportunities for the development of low-power spintronic devices. Full article

Microscopic magnetic stimulation (MSTI) induces electric fields without direct charge injection and can shape localized field gradients with asymmetric micro-coils. Most demonstrations still rely on external drivers, off-chip hardware, or separated coil validation, so the CMOS integration boundary remains poorly characterized. This work presents a fabricated $2\times 1 {\mathrm{mm}}^2$ $0.18 \mathsf{\mu }\mathrm{m}$ CMOS magnetic-stimulation SoC that co-integrates ASK-compatible command decoding, FSM and register-based parameter control, a programmable current–voltage–current triangular driver, and a bent top-metal micro-coil, and it characterizes the on-chip driver-to-coil path together with a substrate-aware field model. Sensing-load reconstruction confirms command-to-waveform programmability, including duration-window decoding, burst-count control, and polarity reversal, with measured slew targets that give a peak current of $I_{\mathrm{pk}}=3.72$–$21.6 \mathrm{mA}$. A quantitative comparison contrasts the current-mode triangular driver with conventional electrode stimulators, a coil-impedance measurement shows the coil stays resistive across 1 to 10 MHz, and the measured total SoC power is about 41 mW. Substrate-aware simulation at a $15 \mathsf{\mu }\mathrm{m}$ target plane shows that the grounded p-substrate retains $35.1$–$40.5\%$ of the no-substrate peak x-directed field-gradient metric. The prototype establishes this electrical programmability and the substrate-aware gradient-transfer loss as a compact design-margin metric for CMOS-integrated magnetic stimulation. Direct biological activation is not claimed and is left to future in vitro validation. Full article

This paper proposes a low-complexity residual-corrected loss-minimization current-reference generation method for permanent magnet synchronous motor (PMSM) drives. Existing loss-minimization control (LMC) methods often rely on lookup tables, numerical optimization, high-order algebraic equations, or explicit approximations based on maximum torque per ampere (MTPA) and maximum torque per voltage (MTPV) references. While effective, these simplified approximations often introduce residual errors relative to the true loss-optimal conditions. To address this, this paper adopts a more consistent iron-loss equivalent-circuit objective and analytically eliminates the torque equality constraint, reducing the LMC problem to a one-dimensional scalar minimization problem of the d-axis current. This paper demonstrates that this reduced objective is strictly convex over the admissible scalar domain, allowing for an exact benchmark solution via a scalar convex solver. The proposed method constructs a resistance-aware initial reference from explicit MTPA and MTPV approximations and then applies a one-step scalar Newton-type residual correction using the gradient and Hessian of the reduced loss objective. The initial reference reproduces the known exact surface-mounted PMSM (SPMSM) LMC solution in the SPMSM limit. The correction direction is proved to be a strict descent direction, and a safeguarded step-size ensures loss reduction compared to the initial approximation. The main novelty is the use of the scalar LMC optimality residual as a fixed-cost correction layer for explicit LMC references. The numerical validation is interpreted as steady-state current-reference mapping accuracy and model-based controllable loss-objective verification against the exact scalar optimum, not as hardware drive-efficiency validation. Tests including the no-MTPV case show reduced current-reference and loss-objective gaps while retaining a fixed-cost structure that may support future embedded implementation after validation; hardware transient and efficiency validation under inverter nonlinearity, temperature variation, saturation, and PWM effects remains for future work. Full article

The LC-filtered permanent magnet synchronous motor (PMSM) drive system presents challenges due to its high-order characteristics, as well as the phase delay and voltage drop introduced between the inverter side and the motor side. These issues make traditional sensorless control methods difficult to apply directly. To address this, this paper proposes a sensorless control strategy based on a second-order generalized integrator (SOGI)-assisted high-order extended state observer (HOESO). This strategy relies solely on DC bus voltage and inverter-side currents to realize precise observation of the motor-side current and back electromotive force (BEMF), thereby significantly reducing system cost. Furthermore, the method enables gain parameter tuning merely by adjusting the observer bandwidth, and it also demonstrates that the system is stable when the estimated current is used to drive the capacitor current feedback active damping (CCFAD). In addition, the voltage differential components are extracted using the SOGI, effectively suppressing high-frequency noise interference. Experimental results obtained on an LC-filtered PMSM platform show that, under a 0.8 N·m step load at 600 rpm and 1200 rpm, the maximum motor-side current estimation errors are 0.66 A and 1.24 A, respectively, and the steady-state rotor position estimation errors are kept within 10°. Compared with direct differentiation, the SOGI-based differential extraction reduces the maximum BEMF estimation errors from 20.16 V and 47.54 V to 10.08 V and 12.96 V, respectively. Full article

To address the structural complexity, limited detection sensitivity, and environmental susceptibility of the stable operating point in conventional fiber-optic current transformers for low-current detection, this study proposes a fiber-optic current transformer based on the coupling of an extrinsic Fabry–Perot interferometer (EFPI) and a lead zirconate titanate piezoelectric ceramic (PZT). In the proposed sensor, a toroidal magnetic core and an induction winding are used as the current pickup unit to convert the measured alternating current into an induced voltage. This induced voltage directly drives the PZT to generate axial displacement, causing periodic variations in the length of the air Fabry–Perot cavity formed between the fiber end face and the coated quartz diaphragm. As a result, the current signal is converted into an optical interference intensity signal. To prevent the static operating point from deviating from the optimal linear region during EFPI intensity demodulation, a DC-component-feedback-based operating point control method is proposed. By adjusting the driving voltage of the fiber Fabry–Perot tunable filter, the center wavelength of the incident narrowband demodulation light can track the optimal operating point of the interference spectrum, thereby improving the stability of the intensity demodulation process. Experimental results show that the fabricated sensor can generate a stable reflected interference spectrum and exhibits a relatively flat frequency response within the range of 0–7 kHz, indicating its potential for power-frequency current detection under the present laboratory conditions. When the measured current is 0.13 mA, the sensor can still produce a distinguishable sinusoidal output signal. When the measured current increases to 75 mA, obvious nonlinear distortion appears in the output signal, indicating that the sensor is approaching the boundary of its linear detection range. Within the linear operating region, the output peak-to-peak value shows good linearity with the measured current. The results indicate that the proposed EFPI-PZT fiber-optic current transformer has the advantages of a relatively simple structure, clear low-current response, and adjustable structural parameters, providing a reference for the miniaturized design and further development of new fiber-optic current sensors. Full article