Hybrid Wireless Power Transfer Research Articles

Enhancing Misalignment Tolerance in Hybrid Wireless Power Transfer System With Integrated Coupler via Frequency Tuning

Enhancing Misalignment Tolerance in Hybrid Wireless Power Transfer System With Integrated Coupler via Frequency Tuning

Energy-Efficient Hybrid Wireless Power Transfer Technique for Relay-Based IIoT Applications

This paper introduces an innovative hybrid wireless power transfer (H-WPT) scheme tailored for IIoT networks employing multiple relay nodes. The scheme allows relay nodes to dynamically select their power source for energy harvesting based on real-time channel conditions. Our analysis evaluates outage probability within decode-and-forward (DF) relaying and adaptive power splitting (APS) frameworks, while also considering the energy used by relay nodes for ACK signaling. A notable feature of the H-WPT scheme is its decentralized operation, enabling relay nodes to independently choose the optimal relay and power source using instantaneous channel gain. This approach conserves significant energy otherwise wasted in centralized control methods, where extensive information exchange is required. This conservation is particularly beneficial for energy-constrained sensor networks, significantly extending their operational lifetime. Numerical results demonstrate that the proposed hybrid approach significantly outperforms the traditional distance-based power source selection approach, without additional energy consumption or increased system complexity. The scheme’s efficient power management capabilities underscore its potential for practical applications in IIoT environments, where resource optimization is crucial.

A High-Efficiency Underwater Hybrid Wireless Power Transfer System With Low Plate Voltage Stresses

A High-Efficiency Underwater Hybrid Wireless Power Transfer System With Low Plate Voltage Stresses

A robust parity‐time‐symmetric hybrid wireless power transfer system with extended coupling range

SummaryInductive power transmission (IPT) and capacitive power transmission (CPT) are currently the two main wireless power transfer technologies. Hybrid power transmission (HPT) systems that combine IPT and CPT can improve transmission performance and are more attractive for some charging applications such as electric bicycles (e‐bikes). However, HPT systems are more sensitive to parameter variations, and the coupling mechanism is prone to misalignment during wireless charging. Therefore, achieving stable output power and constant transfer efficiency over a wide range of coupling coefficient variations is still a major challenge for HPT systems. In this work, the parity–time (PT) symmetry theory is applied to an SS‐type HPT system, and a circuit model of the PT‐based HPT system is developed by using coupling capacitance and coupling inductance. The effect of connecting the plates to the homonymous end or heteronymous end of the coupling coils on the PT symmetry range of the HPT system is discussed. It is found that the heteronymous end connection of the coils can effectively increase the range of constant output power and stable transfer efficiency. Finally, a prototype is built to verify the feasibility and effectiveness of the proposed PT‐based HPT system. The transfer power and efficiency remain constant in the PT‐symmetric range, and the inductive and capacitive coupling coefficients are smaller compared to IPT and CPT systems with the same parameters.

A Hybrid Wireless Power Transfer System With Constant and Enhanced Current Output Against Load Variation and Coupling Misalignment

A Hybrid Wireless Power Transfer System With Constant and Enhanced Current Output Against Load Variation and Coupling Misalignment

A Series of Hybrid WPT Systems With Automatic Switching Between Constant-Current and Constant-Voltage Modes on the Secondary Side

In battery charging applications, wireless power transfer (WPT) technology has unique advantages over wired power transmission. For stationary charging cars, it is necessary to overcome the system performance changes caused by coil misalignment, and the constant-current (CC) mode must be quickly and stably switched to constant-voltage (CV) mode to ensure battery safety. Based on a T-type network, this article presents the basic characteristics of a series of hybrid structures with high misalignment tolerance. Additionally, based on these structures, a series of methods to automatically and quickly switch from CC to CV by changing the resonance compensation structure on the secondary side is proposed without communication or complicated control methods. To verify the performance of the proposed structure, this article presents a reconfigurable system based on a hybrid structure and builds a set of experimental equipment with the power of 200 W. In the CC/CV mode, the misalignment tolerance in the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$X$ </tex-math></inline-formula> -axis can reach 50%, in the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$Z$ </tex-math></inline-formula> -axis can reach 33.33%, and the output current/voltage fluctuation range is less than 5%. In addition, the switching process is stable enough to satisfy charging requirements.

Domestic Induction Heating System With Standard Primary Inductor for Reduced-Size and High Distance Cookware

In this article, a hybrid wireless power transfer system, which combines induction heating (IH) and inductive power transfer functionalities, is proposed to improve the performance of a domestic IH application with small loads weakly coupled to distant inductors. Considering the basic single-inductor domestic IH application, the proposed system adds a secondary inductor with a series compensation capacitor directly attached to the small ferromagnetic cookware. The extended distance can be used to implement the glassless induction concept, where the ceramic glass of typical cooktops is substituted by the kitchen surface itself. The design of the secondary coil is carried out by means of a combination of finite-element and electrical simulations. A design process, including the housing of the resonant capacitors and the selection of the secondary winding number of turns and cabling, is presented. As a result, a prototype is implemented and tested under working conditions up to 1500 W at several distances. Experimental results validate the electrical modeling and simulation. Moreover, thermal results confirm the feasibility of the proposal and validate the adopted strategies for the capacitor housing.

A Link-Independent Hybrid Inductive and Capacitive Wireless Power Transfer System for Autonomous Mobility

A link-independent hybrid wireless power transfer system (HPT) that uses both capacitive and inductive action for autonomous vehicle charging application is presented in this article. A three-leg inverter topology is utilized here. Two legs of the inverter, switched at 85 kHz, are used for inductive wireless power transfer (IPT) and the third leg, switched at 1 MHz, is used for capacitive wireless power transfer (CPT). The three-leg inverter module is realized using SiC and GaN switches. The dual switching frequency operation of the converter enables independent compensation techniques to be adopted for IPT and CPT, bringing the modularity feature in the HPT. The circular inductive-link outer diameter is 460 mm and the parallel plate capacitive-link dimension is 600 mm × 600 mm. The power transfer distance or air gap is 100 mm between both links. The output power ratio of IPT to CPT is 2:1. The effectiveness of the proposed topology is validated experimentally. The advantages of this HPT system are modular-link architecture, improved misalignment performance, and distinct frequency of operation for each link that allows the inductive link to meet the SAEJ2954 standard frequency limits compared with the existing HPT systems proposed for electric vehicle charging to support autonomous mobility.

An efficient design of LC-compensated hybrid wireless power transfer system for electric vehicle charging applications

Wireless power transfer (WPT) is the technology of transferring the electric power through a time-varying electric or magnetic field acting as a transmission medium. A combination between the inductive power transfer (IPT) and the capacitive power transfer (CPT) has been recently developed to benefit from the merits of both systems in order to realize high power transfer with high efficiency through large air gaps and misalignment distances. The output power capability of the existing designs is still limited and needs further enhancement. In this paper, a new hybrid inductive and capacitive wireless power transfer model is proposed, analyzed and simulated. The inductive part composes of a circular spiral coil integrated with a helical coil and supported with cross shape ferrite bars in order to enhance the magnetic coupling ability. The capacitive part consists of four cylindrically evacuated square plates compatible with the inductive part size to facilitate the combination process. Firstly, the system structure is designed using Maxwell-3D simulation tool, then an equivalent circuit model is derived in detail to explicate the working principle. Secondly, a 10.1 kW hybrid system is designed and simulated using MATLAB/Simulink and ANSYS/Simplorer. Excluding the inverter and the rectifier internal losses and considering only the AC losses of the coils represented in their parasitic resistance, a high resultant efficiency equal to 99.37% at a resonant frequency of 1 MHz is achieved. Generally, the results show that the hybrid system could perform better under different air gaps and misalignments than the inductive and the capacitive systems separately.

Throughput performance for full-duplex DF relaying protocol in hybrid wireless power transfer systems

Most of the existing studies on energy harvesting (EH) cooperative relaying networks are conducted for the outdoor environments which are mainly characterized by Rayleigh fading channels. However, there are not as many studies that consider the indoor environments whereas the state-of-the-art internet of things (IoT) and smart city applications are built upon. Thus, in this paper, we analyze a namely hybrid time-power splitting relaying (HTPSR) protocol in a full-duplex (FD) decode-and-forward (DF) battery-energized relaying network in indoor scenarios modelled by the unpopular log-normal fading channels. Firstly, we formulate the analytical expression of the outage probability (OP) then the system throughput. Accordingly, we simulate the derived expressions with the Monte Carlo method. It is worth mentioning that in our work, the simulation and the theory agree well with each other. From the simulation results, we know how to compromise either the power splitting (PS) or the time splitting (TS) factors for optimizing the system performance.

A Dual Frequency Tuning Method for Improved Coupling Tolerance of Wireless Power Transfer System

This letter proposes a dual-frequency tuning method for improved coupling tolerance of an inductively coupled wireless power transfer (WPT) system by exploiting the fundamental and third-order harmonic components of a square-wave voltage out of a full-bridge inverter. A dual-frequency hybrid compensation topology is designed to simultaneously utilize the characteristics of series-series (SS) and LCL-S networks under the two different frequencies. Consequently, the output power of the proposed system under a fixed load is maintained approximately constant against coupling variations. A practical hybrid WPT system with a 100 kHz square-wave excitation and a 10.5 Ω resistive load is built to verify the theoretical modeling and analysis. Experimental results show that the system achieves an approximately constant output voltage and power of around 39 V and 150 W against a coupling coefficient variation from 0.52 to 0.72, with maximum fluctuations less than 5% and 10%, respectively.

Design and Analysis of a New Hybrid Wireless Power Transfer System With a Space-Saving Coupler Structure

This article is to present the design, analysis, and verification of a new hybrid wireless power transfer (HWPT) system, which has a space-saving coupler structure. The key of the design is to simplify the two coupling capacitor plates into one single frame-shaped plate at each side. Then, the coupling coil for inductive power transfer (IPT) is embedded into the metal frame to form a compact hybrid coupler. Meanwhile, the coupling polarity between the coils is specified to realize the superposition of the inductive and capacitive coupling. As a result, the proposed HWPT system can offer a good comprise of efficiency promotion and a space-saving coupler structure simultaneously. To illustrate the system working principles, the equivalent circuit model is first derived. Then, a detailed analysis is conducted in terms of the reflected impedance. Consequently, the mechanism of the efficiency promotion can be clearly explained. Finally, a prototype is constructed with several experiments, which validate the effectiveness of the proposed HWPT system. Results show that an efficiency increase of 14% over the pure IPT is obtained at 35-cm distance. Moreover, the effects of varying the resonant frequency are also carried out to instruct the practical system design.

Design of high efficiency active class E rectifier using PMOS switch for hybrid wireless power transfer

The wireless power transfer (WPT) circuits are very promising to conduct therapy in several conditions especially in neurological stimulation. In the WPT designs, a high efficiency rectification and a DC output regulation are performed simultaneously using active rectifier without the need of an additional regulating circuits. However, the significant ripple appeared at the DC output voltage waveform so that reducing the efficiency of the rectifier. This is due to the application of NMOS as a switching device, where the threshold voltage of NMOS is strongly influenced by the body bias voltage. In this paper, the design of the active class E rectifiers using PMOS switch produces the DC output voltage waveform with an average ripple over 0-100% duty cycle is 16.7%. With simple structure and compact size, this proposed active class E rectifier can be applied for the future Hybrid WPT applications especially in low power operations.

Analysis and Design of Inductive and Capacitive Hybrid Wireless Power Transfer System for Railway Application

Inductive power transfer (IPT) and capacitive power transfer (CPT) are mainly two effective ways to achieve wireless power transfer (WPT). IPT system needs capacitor to compensate the system, while the CPT system requires inductor to tune the system. Therefore, IPT coupler can be used to compensate the CPT coupler and vice versa. In this article, an inductive and capacitive hybrid wireless power transfer (HWPT) system is proposed to improve the system coupler antimisalignment ability. The couplers of IPT and CPT are employed together to compensate each other and transfer power together. Superposition theory is used to analyze the system working principle in detail. With the analysis results, a scaled-down system is built to validate the performance of the proposed approach. Experimental results show that the proposed HWPT system can achieve 653 W output power with 87.7% dc–dc efficiency at the well-aligned condition, and the maximum variation of the output power is 8.3% with the coupler misalignment from 0 to 270 mm (halfwidth of the coupler), which agree well with the analysis results.

Coil Inductance Design for Low Power Hybrid Wireless Power Transfer

This paper presents a coil inductance design for low power hybrid wireless power transfer (WPT). The proposed coil inductance design of transmitter and receiver circuits of 7.1 μH are designed using handmade copper wire structure. Several coils with the variations of wire diameters, coil loop radius, and numbers of loops are proposed to find optimum structure in the low power hybrid WPT. The optimum coil structure is obtained at wire diameter of 0.5 mm, 2.25-inch coil loop radius and 1 MHz operation frequency. The measured transceiver coil design has exhibited peak power transfer efficiency (PTE) of 33.1% at 1 cm distance between Tx and Rx. Therefore, the proposed coil design is applicable to low power hybrid wireless power transfer circuits.

Hybrid coupler for 6.78 MHz desktop wireless power transfer applications with stable open‐loop gain

The open-loop gain of capacitive power transfer (CPT) circuit, especially for applications like wireless charging of laptop or keyboard, is sensitive to the changes of coupling capacitance, which makes the regulating of output voltage and output power difficult. Hybrid coupler has been proved to be able to combine the advantages of both inductive power transfer (IPT) and CPT. In this study, a hybrid coupler is designed with the aim of keeping a stable open-loop gain when the coupling capacitance changes. The structure as well as the operation principles of the hybrid coupler is explained firstly. Then, the open-loop gains of CPT, IPT and hybrid wireless power transfer (HWPT) are derived and followed by a simplified design guideline of the whole HWPT system using the proposed hybrid coupler. Finally, the proposed coupler is verified with a 40 W, 6.78 MHz experimental prototype.

Hybrid Bidirectional Wireless EV Charging System Tolerant to Pad Misalignment

Electric vehicles (EVs) are becoming increasingly popular as a means of future transport for sustainable living. However, wireless charging of EVs poses a number of challenges related to interoperability, safety, pad misalignment, etc. In particular, pad misalignments invariably cause changes in system parameters which in turn lead to increase in losses as well as reduction in power throughput, making the charging process long and inefficient. Consequently, wireless charging systems that are less sensitive to pad misalignments have become preferable. This paper, therefore, presents a hybrid wireless power transfer (WPT) system that charges EVs at constant rate despite large misalignments between charging pads. The proposed charging system uses a combination of two different resonant networks to realize a constant and efficient charging process. A mathematical model is also developed, showing as to how the two resonant networks can be combined to compensate for pad misalignments. To demonstrate the validity of the proposed concept as well as the accuracy of the mathematical model, theoretical performance is compared with both simulations and experimental results of a prototype 3.3 kW hybrid bidirectional WPT system. Results clearly indicate that the proposed hybrid WPT system is efficient and offers a constant charging profile over a wide range of spatial (three-dimensional) pad misalignments.