Wide Load Research Articles

An Economical DWPT System With Mutual Compensation of Segmented Power Supply Rails Based on LCL Topology

For high-power, long-mileage dynamic wireless power transfer (DWPT) system, its economy and adaptability to complex working conditions are the main factors limiting its popularization and application. In this paper, the compensation and power supply of segmented rails are studied, and a DWPT system with mutual compensation of segmented power supply rails based on LCL topology is constructed. By multiplexing components, the number, cost and volume of devices are reduced, and the economy of the system is improved. The power supply topology is optimized to achieve constant-current characteristics over a wide load range to generate a stable high-frequency magnetic field in space and avoid short-circuit current induced by mutual coupling of adjacent rail. The resonant control conditions of the system are derived, and a phase shift control method based on the three-leg inverter is proposed to realize the full range regulation of transmitter current and output power, and improve the adaptability of the system. The characteristics of the proposed DWPT system have been verified by an experimental prototype.

High performance vapor chamber enabled by leaf-vein-inspired wick structure for high-power electronics cooling

The boom of the advanced technologies, such as microprocessors, 5G, and big data, has led the thermal management to be a crucial factor in determining the operating speed, reliability, and efficiency as well as lifetime of electronic devices. As passive heat transfer devices utilizing the liquid–vapor phase change, vapor chambers are greatly attractive due to the high thermal conductivity and passive operation. Here, we present a novel vapor chamber with leaf-vein-inspired wick structure, which could effectively facilitate the condensate to flow back to the evaporation region. Besides, the capillary wick functioned as the supporting structure instead of traditional solid supporting columns to withdraw the deformation of the vapor chamber. The heat transfer performance of the proposed vapor chamber was experimentally investigated under forced water cooling condition, and the effects of the cooling water temperature and mass flow rate were analyzed systematically. The results showed that the vapor chamber could effectively tolerate a wide heat load range from 20 W to 500 W with no noticeable performance degradation, and a minimum thermal resistance of 0.029 °C/W was attained at 200 W. Additionally, increasing the cooling water temperature and decreasing the cooling water mass flow rate could lead to the increase of the total thermal resistance at all heat loads. Finally, compared to other reported works, the vapor chamber featured a lowest thickness and vapor chamber thermal resistance, demonstrating a promising solution for cooling high-power and miniaturized electronics.

A novel digital sensor-less synchronous rectification method for CLLLC resonant converters

With the rapid development of the renewable energy vehicles, pursuing the power converters with high efficiency and high reliability has caught more attention recently. In order to solve those problem with low cost, this paper proposes a sensor-less synchronous rectification method for the CLLLC resonant converters. The precise conduction time of the synchronous switches is obtained based on the analysis of the working principle of CLLLC resonant converter, and the relationship between the SRs switching time and the inverter switching time can be derived as well. To achieve the wide output voltage range, the converter requires wide working frequency. And the correct turn-on and turn-off time for the synchronous switches can be obtained respectively by calculation and piecewise linear function fitting methods within full working frequency range. Compared with traditional synchronous rectification control for CLLLC, which require additional high bandwidth voltage sensors or current sensors, the method proposed in this paper is realized by only one low-cost output voltage sensor. And the proposed method is suitable for high-power applications with a wide voltage and load variation. Moreover, because of the symmetrical topology, this method is valid in bidirectional power transfer. Additionally, the exist analog synchronous rectification control chips suffer from losing accuracy with wide bus voltage variation, however, this method can overcome this shortcoming. Thus, the proposed synchronous rectification method is a low-cost and suitable for high-power, high power density, high efficiency application which benefit from its simple algorithm. Finally, the proposed sensor-less synchronous rectification method is validated by the simulation results and experimental results. The results of simulation and experimental have shown the proposed method offers significant benefits which increases the efficiency of the whole CLLLC system by about 3%, and the reliability of the converter are greatly increased, due to the cooler SRs.

Characterizing the temperature and strain rate dependent tensile strength of amorphous polymer by a theoretical model

AbstractThe temperature and strain rate dependent (TSRD) tensile strength of polymer closely concerns the service safety in wide temperature range and dynamic load. In this study, based on the decoupled modeling method, a theoretical model of TSRD tensile strength of amorphous polymer was established. The model quantifies the relationship between the TSRD tensile strength, Young's modulus, heat capacity, glass transition temperature and melting temperature of amorphous polymer. The model predictions demonstrated an excellent consistency with the experimental data. Furthermore, the influencing factors analysis regarding the TSRD tensile strength were conducted. This study contributes a theoretical method to conveniently predict the TSRD tensile strength of amorphous polymer, and would be helpful to the evaluation and application of polymer in extreme conditions.

Quad-Input Single-Resonant Tank LLC Converter for PV Applications

A quad-input LLC converter for photovoltaic (PV) application is proposed in this paper. In this topology, a single LLC resonant tank is utilized to transfer the energy from four PV panels to the output by using two Y configurations of switches. The PWM generation of all these switches depends on switching frequency and three phase shifts. An MPPT control strategy based on Perturb and Observe (P&O) method has been proposed in this paper to ensure the independent maximum power point tracking (MPPT) for all PV panels. The zero-voltage switching (ZVS) across all the switches for a wide input range and load variations is achievable with this topology. A detailed mode-by-mode analysis followed by the switching waveforms has been illustrated, which led to the gain equation derivation. In that context, a state plane trajectory has also been drawn according to the various modes of LLC topology. Finally, a 500W prototype has been built and tested to verify the operation of the converter. The achieved peak efficiency of the converter is 94.3% when all four PV panels track their maximum power point (MPP) individually.

A Reconfigurable Rectifier-Based Power Improving Method of Free-Standing Two-Coil Magnetic Field Energy Harvesters Over a Wide Load Range

Free-standing magnetic field energy harvesters (FSMFEHs) have promising potential in charging sensors used in electrical power grids. The output power of the FSMFEH is highly dependent on the load resistance. However, the load resistance of the sensors varies over a wide range during the operation process. Therefore, a crucial challenge for an FSMFEH system is to maintain high output power over a wide load range. In this article, an innovative reconfigurable rectifier-based FSMFEH system with two coils connected in parallel is proposed. First, a new structure of two identical coils in parallel is proposed in magnetic energy harvesting applications. Then, a reconfigurable rectifier with two operation modes is developed to incorporate the new coil structure. By switching between the full-bridge mode and the half-bridge mode according to the actual load demand, the proposed FSMFEH can maintain high output power over a wide load range. In addition, the mode transition can be easily achieved by shorting one of the diodes, leading to a simple and low-loss control. The effectiveness of the proposed FSMFEH system is verified based on a laboratory prototype. It is provided that the experimental result is consistent with the theoretical analysis. The output power can be maintained above 8.19mW within the 50Ω to 1500Ω range when the busbar current is 100A.

Damage evolution of the coating/substrate system TiN/X2CrNi18-9 under high indentation loads: experimental and numerical study

Hard coatings, in particular TiN, are widely used as coatings for cutting tools and in the agri-food industry. In the literature, however, few characterizations of hard coatings can be found which define the minimum applied load when the coating starts to fail. In the present study TiN coating was deposited on stainless steel X2CrNi18-9. Vickers and Brinell indentation tests with a wide load range were performed. The main results revealed that the increase of the applied load in Vickers and Brinell indentation influenced the coating and coating/substrate damage evolution. SEM investigation of the Vickers indentation area shows five modes of damage: inclined cracks, radial cracks, lateral cracks, edge cracks, and shear steps. Each damage mode occurs at a specific load range. Parallel cracks already appeared at the edges of the indents at the lowest load of 2 N. For Brinell indentation, cracks start in the coating only at loads higher than F = 307 N. The SEM examinations present damage modes such as circumferential cracks in the border and additional circular cracks in the center of the indent, creating a crack network. Numerical simulations of Brinell indentation were carried out in order to determine the stress distribution in the indent. The comparison of the numerical simulation results with the experimental findings revealed that the coating started to fail at a stress range above 5735 MPa which corresponds to a normal load range of higher than 307 N in Brinell indentation tests. At a load of 613 N cracks were observed.

Skin-Friendly and Wearable Iontronic Touch Panel for Virtual-Real Handwriting Interaction

Touch panels are deemed as a critical platform for the future of human-computer interaction and metaverse. Recently, stretchable iontronic touch panels have attracted attention due to their superior adhesivity to the human body. However, such adhesion can not be named "real wearable", leading to discomfort for the wearer, such as rashes or itching with long-time wearing. Herein, a skin-friendly and wearable iontronic textile-based touch panel with highly touch-sensing resolution and deformation insensitivity is designed based on an in-suit growing strategy. This textile-based touch panel endows excellent interfacial hydrophilic and biocompatibility with human skin by overcoming the bottlenecks of the hydrogel-based uncomfortable sticky touch interface and low mechanical behavior. The developed touch panel enables handwriting interaction with good mechanical capacity (114 MPa), nearly 4145 times higher than pure hydrogel. More importantly, our touch panel possesses intrinsic insensitivity to wide external loading from the silver fiber (<0.003 g) to even heavy metal block (>10 kg). As proof of concept, the textile-based iontronic touch panel is applied to handwriting interaction, such as a flexible keyboard and wearable sketchpad. This iontronic touch panel with skin-friendly and wearable qualitities is helpful for next-generation wearable interaction electronics.

A 13.56-MHz Wireless Power Transfer System With a Wide Operating Distance and Load Range for Biometric Smartcards

This article presents a wireless power transfer system for an increased dynamic range of link distance and load with extended controllability of transmitting power. Under wide link distance and load variation, rectification and regulation in a single-stage to provide a stable 3-V dc voltage <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$V_\text {L}$</tex-math></inline-formula> from a 13.56-MHz sinusoidal waveform at the receiver (RX) <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$LC$</tex-math></inline-formula> tank is performed. For high end-to-end power transfer efficiency and robust operation under link and load variations, the transmitting power <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$P_\text {TX}$</tex-math></inline-formula> is controlled by the reflected impedance from the RX to the transmitter (TX). To extend the controllability of the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$P_\text {TX}$</tex-math></inline-formula> , antennae with high quality factors and a series-connected RX <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$LC$</tex-math></inline-formula> tank structure are applied. A working-only-when-needed rising edge detector and a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\Delta \Sigma$</tex-math></inline-formula> -based falling edge detector for low power and accurate zero current detection are presented. A digital <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\Delta \Sigma$</tex-math></inline-formula> -based voltage regulation controller is adopted for stable dc supply with fast transient response. The implemented IC in a standard 65-nm CMOS process measures 0.14-mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^\text{2}$</tex-math></inline-formula> active silicon area. The proposed work operates under a wide range of link distance (30–185 mm) with a large load dynamic range (10000×, 60 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\Omega$</tex-math></inline-formula> –600 k <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\Omega$</tex-math></inline-formula> ).

Review and comparison of methods for limiting leakage currents in single-phase transformerless PV inverter topologies

Transformerless inverters are widely used in different photovoltaic nonisolated ac module applications, mainly in grid-tied photovoltaic (PV) generation systems, due to the benefits of achieving high efficiency over a wide load range, and low cost. Various transformerless inverter topologies have been proposed to meet the safety requirement of low ground leakage currents, such as specified in the VDE-4105 standard and low-output ac-current distortion. Topology modifications of transformerless full bridge inverters are designed to balance and maintain a constant common mode output voltage, thereby eliminating or reducing leakage currents. This article reviews and compares the different methods for limiting leakage currents in known topologies of the full-bridge transformerless inverters, such as: H4, H5, H6, HERIC, and their improvements. The main topologies and strategies used to reduce the leakage current in transformerless schemes are summarized, highlighting advantages and disadvantages and establishing points of comparison with similar topologies. To compare the properties of different medium to high power inverters, PV inverter topologies were implemented using IGBTs and tested with the same components, same simulation parameters in PSPICE to evaluate their performance in terms of energy efficiency and leakage current characteristics. The detailed power stage operating principles, extended PWM modulator, and integrated universal gate driver with galvanic isolation in the transmission path of control signal for all IGBTs of the inverter, as well isolated and floating bias power supply for gate drivers are described.

A Survey on Market Based Economic Security Dispatch (MBESD) Policy in Supply Chain Power Market

Abstract: Power System safety and financial dispatch is principal intention to restructuring of electricity system. Economizing on gas price and minimizing emission of gases (CO, CO2, NO2, SO2) are one approach of to maintained safety of machine however solely this system are no longer archived this label of security. Now in pandemic state of affairs when energy financial increase is falling down then it is very tough to maintained desirable device security. In this pandemic scenario country wide load dispatching centers play essential position to overcome this situation. This paper is excessive lightening and mentioned some new current procedural schemes. We are additionally put into effect a new idea (MBED).This paper is exposes special method to enhancement of Power Policies. This method shall be relevant to all thermal ISGS (Inter –State – Generating Station) that are regional entities collaborating in RRAS mechanism and whose tariff is decided or adopted with the aid of the CERC (Central Electricity Regulatory Commission) for their full capacity. Here we are mentioned all on the foundation of NLDC, RLDC, RPCS, SCED exclusive adopting schemes and comparative studies.

An overview of analysis methods and evaluation results for caching strategies

We survey analytical methods and evaluation results for the performance assessment of caching strategies. Knapsack solutions are derived, which provide static caching bounds for independent requests and general bounds for dynamic caching under arbitrary request pattern. We summarize Markov and time-to-live-based solutions, which assume specific stochastic processes for capturing web request streams and timing. We compare the performance of caching strategies with different knowledge about the properties of data objects regarding a broad set of caching demands. The efficiency of web caching must regard benefits for network wide traffic load, energy consumption and quality-of-service aspects in a tradeoff with costs for updating and storage overheads.

Mechanical behavior of nanorubber reinforced epoxy over a wide strain rate loading

Nanorubber/epoxy composites containing 0, 2, 6 and 10 ​wt% nanorubber are subjected to uniaxial compression over a wide range of strain rate from 8 ​× ​10−4 s−1 to ∼2 ​× ​104 s−1. Unexpectedly, their strain rate sensitivity and strain hardening index increase with increasing nanorubber content. Potential mechanisms are proposed based on numerical simulations using a unit cell model. An increase in the strain rate sensitivity with increasing nanorubber content results from the fact that the nanorubber becomes less incompressible at high strain, generating a higher hydro-static pressure. Adiabatic shear localization starts to occur in the epoxy under a strain rate of 22,000 s−1 when the strain exceeds 0.35. The presence of nanorubber in the epoxy reduces adiabatic shear localization by preventing it from propagating.

Ink Based on the Tunable Swollen Microsphere for a 3D Printing Hydrogel with Broad-Range Mechanical Properties.

The development of the effective 3D printing strategy for diverse functional monomers is still challenging. Moreover, the conventional 3D printing hydrogels are usually soft and fragile due to the lack of an energy dissipation mechanism. Herein, a microsphere mediating ink preparation strategy is developed to provide tailored rheological behavior for various monomer direct ink writings. The chitosan microspheres are used as an exemplary material due to their tunable swelling ratio under the acid-drived electrostatic repulsion of the protonated amino groups. The rheological behaviors of the swollen chitosan microsphere (SCM) are independent on the monomer types, and various functional secondary polymers could be carried at a wide loading ratio by the acid driving. The SCM reinforces the hydrogel as the sacrificial bonds. With the adjustable composition, the 3D printing hydrogel mechanical properties are tunable in wide windows: strength (0.4-1.01 MPa), dissipated energy (0.11-3.25 MJ m-3), and elongation at break (47-626%). With the excellent printing and mechanical properties, the SCM inks enable multi-functional integration for soft device production, such as 4D printing robots and wearable strain sensors. We anticipate that this microsphere mediating 3D printing strategy can inspire new possibilities for the design of the robust hydrogels with a broad range of functionalities and mechanical performances.

A Load Adaptive Hybrid DPS Control for DAB to Secure Minimum Current Stress and Full ZVS Operation Over Wide Load and Voltage Conversion Ratio

Wide variations in voltage conversion ratio and loading are the most important parameters to consider when designing off-board EV chargers to achieve high power density and efficiency. Dual phase shift (DPS) modulation provides a better way for dual active bridge (DAB) DC-DC converter operation when load side parameter variation is utmost important. To accomplish this, conventional DPS control is modified to ensure zero voltage switching (ZVS) across the entire load range despite wide variations in voltage conversion ratio. The designed control provides ZVS of all FETs as compared to the conventional DPS control over full loading range. For this, magnetizing inductance of HF isolation transformer is utilized and designed to shape the secondary side current for getting ZVS for both active legs. The light loading performance of the converter is improved with the bidirectional conduction angle control. The hybrid utilization of DPS control is incorporated with minimum peak current stress considerations. A Karush-Kuhn-Tucker (KKT) method based on Lagrange's multipliers is used for mathematical derivation of optimized solution of both control parameters. Performance of designed control is verified using experimental results for wide variation in battery terminal voltage. For validation, a 1250 W laboratory prototype is developed. A comparison of ZVS regions among the conventional and designed modulation technique, shows the effectiveness under wide voltage and loading scenarios.

A Hybrid Load Matching Method for WPT Systems to Maintain High Efficiency Over Wide Load Range

The efficiency of a wireless power transfer (WPT) system is highly dependent on the load resistance. However, the load resistance, such as the battery, is not constant during the charging process. Therefore, a crucial challenge for a WPT system is to keep high efficiency over wide load range. In this work, a hybrid load matching method for WPT systems is proposed to achieve high efficiency. The basic principle of this system is to use a hybrid load matching method, i.e., adding an <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${L}$ </tex-math></inline-formula> – <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${C}$ </tex-math></inline-formula> resonant matching network and choosing the rectifier operation modes (full-/half-bridge), to convert the load to an optimal range. Then, the system efficiency can be kept at the top regions of the efficiency curves. Finally, a prototype is built to validate the performance of the WPT system with the proposed approach. The experimental results show that the optimal load of the WPT system can be transformed from 30 to 60, 120, and 240 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Omega $ </tex-math></inline-formula> , and the efficiency of the proposed system can be maintained above 89% from 10 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Omega $ </tex-math></inline-formula> (527.8 W) to 600 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Omega $ </tex-math></inline-formula> (8.64 W).

A Bidirectional Onboard Charger With Multistep Constant Current Charging Capability

This article realizes a bidirectional onboard charger (OBC) for light electric vehicles (LEVs), with multistep-constant-current (MSCC) charging capability. In this MSCC charging operation, the battery current is reduced during the peak-load hours and resumes the rated charging operation amid the off-peak load hours. Since this MSCC operation is a wide load range operation, the controllers of the front-end converter (FEC) and back-end converter are modified. In this context, a Hermite polynomial-derived functional link neural network (H-FLNN)-based deadbeat predictive current controller (DPCC) is introduced to improve the performance of the FEC of the OBC. Moreover, the HFLNN-based DPCC for the FEC regulates the grid current quality during MSCC and distinct operating conditions such as grid voltage sag and swell, distorted grid voltage, and the presence of dc offset error in the measured grid voltage. A laboratory prototype of a 1.1-kW rating is developed to verify the efficacy of the H-FLNN DPCC to keep the grid current power quality (PQ) within the International Electrotechnical Commission (IEC)-61000-3-2 standard throughout the operation. Moreover, the effectiveness of the design is verified amid the grid voltage sag and swell and distinct operating conditions. The experimental analysis depicts that the rated efficiency of the developed laboratory prototype is 90.18% and the analytical power density is 64.16 W/in3. Furthermore, the vehicle to grid (V2G) operation validates the satisfactory design of OBC for bidirectional operation. At last, the comparison of the presented system with existing systems is given to summarize the advantages of the presented system over the existing systems.

Part-load performance prediction of a novel diluted ammonia-fueled solid oxide fuel cell and engine combined system with hydrogen regeneration via data-driven model

This paper proposes a novel diluted ammonia-fueled solid oxide fuel cell and X-type rotary engine (SOFC-XRE) combined system with hydrogen regeneration sub-system to realize high energy conversion efficiency. The combined system key design parameters and geometric parameters are optimized. The influences of SOFC inlet temperature, stack fuel utilization ratio, stack excess air ratio and pressure ratio across membrane for permeating hydrogen on system off-design performance are investigated. Meanwhile, the improved off-design performance of combined system is revealed by comparing with standalone SOFC. The data-driven neural network model (NNM) is established for predicting system part-load performance based on the off-design performance datasets. The optimal system operation parameter combinations and performances in a wide power load range are obtained by combining data-driven NNM with particle swarm optimization (PSO) algorithm. The results show that the cell stack temperature gradient decreases with decreasing fuel flow rate coefficient. The stack fuel utilization ratio has a larger effect on combined system energy efficiency than the fuel flow rate coefficient. The optimal membrane pressure ratio and fuel flow rate coefficient decrease with decreasing power load. The combined system energy efficiency is increased by 5.94% as the power load is decreased by 75%, while it is decreased by 2.1% as the power load is increased by 20%. The combined system energy efficiency is 10.9–12.2% higher than standalone SOFC in a wide combined system power load range of 120–25% without carbon emission.

Improved Dynamic Performance of the Fuel Cell-Fed Boost Converter Using Super Twisting Sliding Mode Control Strategy

Nonlinear controllers are useful if the equations governing the system dynamics are nonlinear. The fuel cell (FC)-fed boost converter is a nonlinear system as the VI characteristics of the fuel cell and the output voltage to duty cycle transfer function of the boost converter are nonlinear. The choice of a nonlinear controller depends on the dynamic performance of the FC-fed boost converter for wide load variations. This paper compares the performance of the system using conventional sliding mode control (CSMC) and super twisting sliding mode control (STSMC) strategies for tight voltage regulation for the load disturbance and reference voltage tracking. Simulation and experimental results of the fuel cell-fed 600 W boost converter prove the supremacy of STSMC strategy over CSMC strategy in terms of overshoot, undershoot, settling time and chattering reduction.

Power-Spilt-Based Wireless Charging System With Communication-Free Coordination Control

In this article, a power-split-based wireless charging system (WCS) with communication-free coordination control is proposed to combat wide load and coupling variations. By using a magnetic integrated inductor, two power delivery channels are created from a single receiver coil. Large portion of received energy is directly delivered to the load. Small amount of energy is converted by using a low-voltage low-power dc–dc converter to regulate the output voltage or current achieving constant voltage (CV) or constant current (CC) charging operation. This proposal achieves higher power conversion efficiency than the traditional two-stage cascaded converter WCS. Since the dc–dc converter only processes partial power of the WCS system, this proposal reduces the voltage stress of the devices and design difficulty. A communication-free coordination control is applied, which is established by sensing the input current drop caused by the burst operation of the partial-power dc–dc converter. Thus, the CC-CV charging is realized by PWM control at the receiver (Rx) side, and the inverter is regulated with subharmonics control scheme to maintain nearly constant Rx coil current. Simulation results for both high-voltage high-power scenarios and low-voltage low-power (LVLP) scenarios are provided to investigate the operation of the proposed WCS. Finally, experimental results are captured from a 250 W/60–84 V LVLP prototype to validate the feasibility and practicability of proposed concept.