Sub-resonant frequency controlled (SRFC) inductive wireless power transfer systems (IWPTS) have proven their effectiveness in applications requiring both constant current output and robustness to variations in load and coupling. Therefore, this approach offers an attractive alternative to conventional approaches. The natural limitation of such systems becomes apparent when they are required to operate in a constricted frequency band. Previous studies have explored methods for expanding the coupling tolerance of such systems under these conditions; however, these improvements were shown to come at the cost of reduced system efficiency, introducing an inherent performance trade-off. In this paper, a different approach is examined, in which the effect of allowing a controlled current derating on coupling tolerance is studied. The relationship between allowable current derating and achievable coupling tolerance is analytically derived, providing clear insight into associated system behavior. The proposed analysis is validated through simulations conducted in PSIM, demonstrating close agreement with theoretical predictions.

Active ripple suppression branches (ARSBs) are widely employed in switching power converters interfacing ripple-sensitive devices such as batteries, supercapacitors, hydrogen electrolyzers, fuel cells, and photovoltaic panels. Conventional ARSBs share the main converter DC-link voltage and require inductance comparable to that of the primary power stage, resulting in high semiconductor voltage stress and bulky magnetic components. Recent studies have proposed supplying the ARSB from a lower auxiliary voltage source, significantly reducing both inductance value and semiconductor voltage ratings. This paper shows, however, that lowering the ARSB rating while keeping the series capacitance value unaltered inherently increases residual current ripple, degrading ripple-cancellation performance. It is then demonstrated that this limitation should be overcome by increasing the ARSB capacitance in inverse proportion to the rating reduction, thereby restoring ripple suppression performance. Furthermore, it is revealed that for converters operating at a fixed duty cycle, a unique operating point exists where the ARSB capacitor can be eliminated without sacrificing the ripple attenuation ability of the circuit. The resulting capacitorless implementation reduces component count, size, complexity, and cost while improving ripple suppression. Simulation and experimental results validate the theoretical analysis and confirm the feasibility and effectiveness of the proposed capacitorless open-loop operating ARSB.

This article presents a hardware-efficient optimal error-priority control (OEPC) strategy for series-end voltage source inverters (SE-VSIs), enabling high-performance zero-sequence current (ZSC) suppression with minimal computational cost. Unlike conventional methods such as multivector MPC or 3-D-space vector modulation (SVM), OEPC eliminates complex real-time calculations and auxiliary compensators by using a compact 1-D lookup table (LUT) for direct phase-wise current control in ABC coordinates. This deterministic LUT-based approach achieves sub-microsecond execution on low-cost digital signal processor (DSPs) and is easily deployable on microcontrollers or programmable logic devices, making it ideal for cost-sensitive industrial applications. In addition, OEPC integrates adaptive switching frequency control to reduce switching losses and improve electromagnetic interference (EMI) performance. Comprehensive validation through digital simulations, controller-hardware-in-the-loop (C-HIL) tests, and laboratory experiments with physically unbalanced RL loads demonstrate robust ZSC suppression, superior current quality, and maximal DC-bus utilization under challenging conditions. A comparative analysis further confirms OEPC’s intrinsic fault tolerance against inter-turn short circuits (ITSCs), preventing the current runaway observed in conventional schemes. These results establish OEPC as a practical, scalable alternative to computationally intensive modulation-based strategies for industrial motor drives.

It is well-known that employing PI+Notch controller as DC link voltage regulator in power factor correction rectifiers (PFCR) permits attaining better transient response to step-like load variations compared to widely-used type-II controller under similar grid-side current total harmonic distortion (THD) and phase margin constraints. However, in case grid frequency uncertainty is considered, PI+Notch controller design process yields a system of four nonlinear analytical equations with five unknowns, giving rise to infinite amount of feasible coefficient sets. This work proposes a methodology for identifying the set optimizing PFCR transient response to a step-like load variation. Simulations accurately validate the proposed design methodology.

It is well-known that fixed-frequency constant-coupling series-series capacitively compensated inductive wireless power transfer systems (IWPTSs) may be designed to operate with certain load independent voltage gain (LIVG) value within a region defined by loosely coupled transformer (LCT) parameters. Since LCT parameters values are not arbitrarily selectable in practice, the desired LIVG value may reside outside the attainable region. In such a case, utilizing an inductor (rather than capacitor) as one of the series compensation elements allows extending the attainable LIVG values range. Unfortunately, the method may also cause significant increase in reactive transmitting side currents, yielding overrating of inverter transistors, transmitter side LCT coil and compensation elements. As a remedy, this article proposes utilizing an additional capacitor across ac-side rectifier terminals, yielding two novel mixed inductive-capacitive compensation. The proposed topologies are then thoroughly analyzed providing expressions for IWPTS output voltage range and coil-to-coil, followed by compensation components selection and sizing guidelines. It is revealed that despite definite transmitting side components rating reduction, coil-to-coil efficiency is deteriorated in some cases (while improving in others) and corresponding criteria are derived. Analytical findings are accurately supported both by simulations and experiments, demonstrating a reduction of up to 73% in inverter current rms and a maximum efficiency increase of 41% under certain operating conditions.

The letter focuses on clamped-type passive magnetic energy harvester equipped with constant-valued series AC-side capacitor (cCs-MEH), supplying power to a constant voltage load (CVL) representing a battery or regulated DC bus, via diode bridge rectifier. Such an arrangement may serve as, e.g., powertrain of a platform for uninhabited aerial electrical vehicle batteries charging residing in the vicinity of overhead power lines. It was recently shown that series-connected capacitor addition allows to enlarge the harvested power by up to 27% due to decoupling of the load from the voltage applied to transformer core. However, the capacitance value must be adjustable to allow maximum harvested power increase under arbitrary primary current magnitudes, significantly complicating the system and reducing reliability. On the other hand, equipping the MEH with a constant-valued series capacitance seems to be more practical. Yet, harvested power boost is expected to be lower than the above-mentioned amount. This brief aims to bridge the gap by discussing sizing process of series capacitance value and assessing the power harvesting potential of a cCs-MEH driving a CVL within certain range of primary current magnitudes. Such an investigation has not been reported in the literature so far. In addition, it is revealed that a cCs-MEH would be outperformed by an optimally designed series capacitorless MEH (utilizing the same core) under low primary currents. Experimental results of a cCs-MEH clamped on conductor carrying 50-350 A, 50 Hz currents are provided to validate the findings.

The paper examines the performance of grid-connected power factor correction (PFC) front ends operating under an integrator-less DC-link voltage controller equipped with a notch filter. Unlike conventional controllers, which rely on integral action to eliminate steady-state voltage errors, the proposed approach removes the integrator term to improve dynamic performance. It is demonstrated that elimination of the integrator allows a significant increase in the achievable control bandwidth compared to existing solutions. As a result, the system exhibits a nearly transient-free response to step-like load variations, with substantially reduced settling time and voltage deviation. These benefits are achieved at the expense of a nonzero yet tolerable steady-state error in the average DC-link voltage, which is analytically found to be proportional to system loading. The analysis further shows that the magnitude of this error depends on the level of grid-frequency uncertainty. To facilitate practical implementation, a systematic controller design methodology is developed. Guidelines for deriving the controller coefficients are provided in the form of nonlinear analytical equations, considering grid-side current total harmonic distortion, phase margin of the DC-link voltage loop, and grid-frequency uncertainty as design constraints. Theoretical findings are validated through simulations and experiments. Close agreement between analytical predictions, numerical results, and experimental measurements confirms the validity of the proposed approach and demonstrates its effectiveness as an alternative to conventional integrator-based DC-link voltage control schemes for grid-connected PFC applications.

Sub-resonant frequency (SRF) operation of inductive wireless power transfer systems (IWPTS) allows attaining constant current (CC) output under varying coupling and output voltage conditions while minimizing transmitter volt-ampere (VA) rating. Unfortunately, SRF-operated IWPTS equipped with diode rectifier-based receivers are uncapable of reducing the output current freely below rated value. This drawback prevents their employment in applications where a wide range of output currents is essential (e.g. Li-ion battery charging, characterized by rated constant current output during constant current stage and gradually decreasing current output down to a near-zero value during constant voltage stage). To bridge the gap, this work proposes equipping the IWPTS with a semi-active rectifier (SAR) based receiver and utilizing SRF control of the transmitter in conjunction with phase-shift (PS) control of the receiver to attain full system controllability under different coupling and varying output voltage conditions. Feasibility of the proposed methodology is successfully validated by experiments.

This paper presents a ripple-free DC/DC converter tailored for fixed duty-cycle applications where current ripple reduction is critical. Conventional interleaved converters achieve ripple mitigation only at specific operating points and require multiple synchronized power legs, while stacked topologies extend cancellation over the full duty-cycle range but rely on series capacitors, large inductors, and high-voltage switches. The proposed solution overcomes these limitations by introducing a ripple cancellation branch that operates without a series capacitor and is electrically decoupled from the main DC-link. This configuration enables the use of small inductors and low-voltage switches while eliminating the need for PWM synchronization. Simulation results confirm that the proposed topology achieves complete ripple suppression with reduced complexity and component stress, making it a compact and efficient alternative for fixed-duty-cycle power conversion.

Recently, a family of single-phase inverters achieving output switching-ripple cancellation by employing active and passive ripple elimination branches was revealed and demonstrated. This work develops analytical expressions for device stresses in switching-ripple-free inverters with either active or passive ripple elimination branches. Simulation results are shown to accurately match corresponding analytical predictions, validating the proposed methodology.

It was recently demonstrated that addition of an AC side series-connected capacitor allows to enlarge power throughput of a passive magnetic energy harvester (MEH) due to decoupling of the voltage applied to transformer core from the load. The capacitor absorbs part of the load-imposed voltage, yielding core saturation entrance delay. On the other hand, output characteristics of a series capacitor-equipped MEH (cCs-MEH) are shown to be different from its capacitor-less counterpart. This brief reveals that optimal (in terms of harvested power) load for a cCs-MEH possesses constant resistance characteristics when operating above certain primary current magnitude, as opposed to constant-voltage characteristics load optimal for a capacitor-less passive MEH. Analytical expressions are derived for both optimal constant resistance load value and corresponding average harvested cCs-MEH power. Experimental results accurately validate the presented findings.

It is known that general resonant power conversion circuits are typically driven by square wave inverters, where measured signals are generally well-aligned with expected waveforms in low-power applications. However, in practical pulsed high-power applications (e.g. nuclear fusion plasma heating), inverter output voltage is often distorted and does not maintain the square wave shape due to parasitic components of printed circuit board (PCB) typically imposed by conductor traces and switching devices. The paper proposes a simple procedure for quantifying parasitic components values from experimental data thus improving modeling accuracy. Simulations and experiments are carried out to support the proposed methodology.

This paper presents a control strategy for a Dual-Winding Active Magnetic Energy Harvester (D-AMEH) designed to supply a constant power DC load while safely charging a battery. By modulating the power transfer window on the battery side, the system dynamically regulates power flow through a digital controller operating in three modes: Maximum Power Point Tracking (MPPT), Constant Current (CC), and Constant Voltage (CV). This control method ensures efficient energy extraction and battery protection under varying power line conditions. The proposed method is validated through PSIM simulations, demonstrating robust operation across different current amplitudes and battery states.

The paper proposes a methodology for deriving static control-to-input average power and control-to-output average power characteristics of an active magnetic energy harvester (AMEH) clamped on sinusoidal current-carrying conductor (e.g. overhead power line) while feeding a constant voltage type load (e.g. uninhabited aerial vehicle battery). Transfer window opening instant serves as the control variable while corresponding closing instant is imposed by AMEH parameters to impose full magnetic core utilization. Analytical expressions for average power harvested by the AMEH from a current-carrying conductor are derived first within feasible range of control input variable values. Then, corresponding conversion losses are assessed to estimate the amount of average power provided by the AMEH to a load. It is revealed that control-to-output power characteristic is non-monotonical for a given value of primary current magnitude, possessing a single maxima. Finally, the paper demonstrates that the output average AMEH power may be smoothly regulated between zero and the maximum level only within a limited region of control input variable values. Presented analytical findings are accurately supported by experimental results of an AMEH clamped on a conductor carrying 100A - 300A, 50Hz currents (typical for medium voltage power line).

The paper proposes a novel dual-winding active magnetic energy harvester (D-AMEH), clamped around single power line conductor carrying AC currents with time-varying magnitude while supplying a constant power DC load via an uncontrolled rectifier (e.g. 24/7 aerial marker ball lighting). To allow continuous power flow to the load despite intermittent nature of power line current magnitude, an energy storage unit (rechargeable battery) is integrated into the system via an additional secondary winding, creating an AC-coupled, isolated hybrid energy system with completely decoupled battery and load voltages. The D-AMEH simultaneously harvests the maximum power from the current-carrying conductor and feeds the load with constant power, letting the battery to seamlessly match the difference between harvested and consumed power. Analytical expressions for system currents and voltages are developed, followed by conversion losses estimation. The revealed findings are accurately supported by experiments, demonstrating close matching with corresponding analytical predictions.

In many practical applications, such as electric vehicle charging and smart transformers, reverse power flow is significantly lower than forward power flow. Designing a full-rated bidirectional DC/DC converter in such cases leads to increased hardware costs. To address this, recent research has explored isolated topologies that support asymmetrical bidirectional power flow at reduced cost. This manuscript investigates an asymmetrical bidirectional DC/DC (AB-DC/DC) converter that integrates a partial-scale active bridge and a partial-scale diode bridge connected in parallel on the secondary side. Passive power sharing between these bridges is controlled by selecting appropriate coupling inductors, but practical magnetic tolerances cause power imbalances. To mitigate this, a novel modulation technique is proposed to enable active power sharing, allowing power transfer from the diode bridge to the active bridge. The study covers various operating regions, including discontinuous conduction mode (DCM), continuous conduction mode (CCM), dual-active-bridge (DAB) mode, and two hybrid regions, where the diode bridge operates in DCM and the active bridge in CCM. Closed-form power expressions and boundary conditions are derived for all modes. The proposed strategy is validated through simulations and experimental measurements on a hardware prototype, demonstrating consistent waveform behavior and confirming the feasibility of active power transfer from the diode bridge to the active bridge.

The paper quantifies controllability of power harvested by a clamped-type active magnetic energy harvester (AMEH), supplying power to constant voltage load (CVL) via controlled rectifier. The AMEH is assumed to be clamped around a 50Hz power line conductor carrying relatively high currents. Transfer window opening instant is considered as the system control input and its influence on harvested AMEH power within feasible operation range is derived analytically and validated experimentally. Experimental results are shown to accurately verify corresponding analytical predictions.

The paper establishes an analytical relation between the power supplied to a certain constant voltage load (CVL) by a pre-designed clamped-type active magnetic energy harvester (AMEH) and the transfer window opening instant, serving as the system control input, for different values of primary current magnitude. Feasible control variable regions are identified and analyzed thoroughly, demonstrating the possibility of smooth output power regulation from maximum value down to zero level. Such a feature is useful in applications where load capability to absorb power is limited (e.g. battery charging). Experimental results accurately match corresponding analytical predictions.

It is well-known that in high-current high-frequency resonant power conversion applications, values of components may differ under load from the values in rest. Consequently, it would be beneficial to develop a simple yet accurate methodology for extracting components values from experimental data. The paper proposes such a procedure, allowing to quantify the value of parasitic inductance typically imposed by relatively long cables in addition to actual load inductance and resonant capacitance under load. Simulations and experiments are carried out to support the proposed methodology.

The paper presents theoretical analysis and practical design of 150W, 48VDC-to-200VDC strongly-coupled inductive wireless power transfer link (IWPTL) for a through-glass AC power delivery system into existing wireless-ready sealed industrial glove box. One of the wireless-ready glove box walls comprises pre-installed dual-side identical transmitting and receiving coils (to assure direction-insensitive installation and confusionproof repair). The load residing within the enclosed compartment requires a 120V, 60Hz AC voltage supply, created by an off-the-shelf buck-topology inverter powered by the proposed IWPTL operating in loadindependent output voltage (LIVO) mode without any feedback. It is shown that due to adoption of symmetrical coils and operation under high coupling coefficient, it is impossible to attain the required voltage gain employing classical series (capacitor) - series (capacitor) compensation. Consequently, the recently revealed series (capacitor) - series (inductor) compensation is adopted in order to attain the required voltage gain value. It is further shown that the output voltage of a practical capacitor-inductor compensated IWPTL remains loaddependent even under LIVO frequency operation, yet residing within a certain range defined in the paper. Expression for coil-to-coil efficiency of the proposed arrangement is also established in this work. Functional feasibility of the proposed system is accurately supported by simulations and experiments.