Wireless Power Transmission Research Articles

Soft ferrite 3D printing of magnetic couplers of inductive power transfer systems

AbstractTraditional soft ferrite manufacturing is limited to simple geometries and materials, while 3D printing offers greater flexibility for complex designs. Notably, soft ferrites are crucial for magnetic couplers (pads) in inductive power transfer (IPT) systems to achieve efficient wireless power transmission. The adoption of soft ferrite 3D printing in IPT systems could lead to significantly improved magnetic coupler design, yet research in this area is limited. Hence, the paper first makes a comprehensive comparison of the existing soft ferrite 3D printing methods to ascertain their suitability for magnetic couplers in IPT systems, and then proposes the binder jetting (BJT) as a potential 3D printing approach that could be appropriate for IPT magnetic coupler implementation being versatile, cost‐effective, and suitable for large‐scale manufacturing with high precision. This paper explores the suitability of BJT by 3D printing toroid cores with Mn–Zn ferrite powder under different sintering temperature profiles. Experimental results are presented to show that toroid cores can be 3D printed with high printing precision, mechanical strength, and a relative permeability of 10. This paper also highlights the impact of sintering temperature on 3D‐printed cores, the challenges, limitations, and future research directions of soft ferrite 3D printing for IPT magnetic couplers by the BJT method.

A double half-bridge series-matrix converter with symmetric modulation for single-stage wireless power transmission without polarity detection

A double half-bridge series-matrix converter with symmetric modulation for single-stage wireless power transmission without polarity detection

Three-dimensional transmitter for omnidirectional wireless power transmission: design and experiment

Three-dimensional transmitter for omnidirectional wireless power transmission: design and experiment

High-Performance Wireless Power and Data Transmission System for Medical Implant Devices Using ASK Modulation

Wireless power and data transmission (WPDT) solutions for medical implants are highly desired. However, achieving a high-power transmission efficiency and data rate simultaneously over an inductive link remains a significant challenge. This paper presents an innovative WPDT circuit that incorporates additional MOSFETs with an inductor in a Class-E power amplifier (PA), achieving amplitude-shift keying (ASK) modulation to address this issue. Firstly, the efficiency of the inductive power transmission link and Class-E PA was analyzed, providing design insights. Then, leveraging the insights, the proposed circuit was designed in such a way that it could effectively switch between two load networks to maintain high transfer efficiency for ASK modulation. Based on the load networks, the relationship between introducing the inductor’s value and the data modulation index (MI) was derived to help achieve the desired high-power transmission efficiency. Additionally, the design and calculation of the proposed circuit are also presented. Finally, the proposed circuit was validated through simulations and experiments, demonstrating a power delivery to a load of 84.1 mW with a power transmission efficiency of 70.8% at a data rate and carrier frequency of 3 Mbps and 16 MHz, respectively. Furthermore, the bit error rate (BER) is less than 10−6 with an MI of 10%.

Dielectric Resonator Antennas for RF Energy-Harvesting/Wireless Power Transmission Applications: A state-of-the-art review

This article presents an overview of dielectric resonator (DR)-based sensing elements and their applications in RF energy-harvesting (RFEH) and wireless power transmission (WPT) systems. With increased wireless applications, the demand for electrical energy goes up, thereby enabling the development of various energy sources. RF energy is widely available and the most efficient energy source. Although DR antennas (DRAs) have been studied extensively in the last few decades, they have not been employed in RFEH and WPT applications. The intention of the proposed article is 1) to provide an overview of the DRA for RFEH and WPT applications; 2) to accommodate various performance enhancement approaches for the DRA; and 3) to highlight the research gap for developing a complete rectenna system that helps future researchers. We believe that this survey may help the DRA.

Design of Magnetic Coupler for Wireless Power Transmission System Based on Magnetic Field Reconstruction

Design of Magnetic Coupler for Wireless Power Transmission System Based on Magnetic Field Reconstruction

Rotation-Tolerant Wireless Power Transmission Scheme with Smart Positioning for Cognitive Research on Moving Animals.

This article presents a novel wireless power transmission scheme designed for moving loads. Specifically focused on compensating for the tilt misalignment of the receiver. By utilizing phase-shifted excitation signals from an array of transmitters, the proposed scheme effectively mitigates the impact of misalignment, locally. The application of this scheme holds particular relevance for studying the behavior of moving animals in cognitive research. The system incorporates a cage with two transmitter arrays positioned on the top and bottom sides. To smart determining the receiver's position, the proposed structure utilizes current feedback from the driving circuits and employs SVM (Support Vector Machine) classification algorithms for positioning. Furthermore, when the receiver coil is tilted, a phase shift mechanism significantly enhances the power delivered to the receiver. Additionally, the use of an overlapped transmitter array enhances rotation tolerance and improves the uniformity of the magnetic fields for moving objects. The performance of the proposed scheme is validated through extensive simulations and measurements using a fabricated prototype. Notably, the designed system achieves a power delivery of 296 mW to the load at a 90° angular misalignment, compared to 1.67 µW delivered by conventional array system.

An Interoperable Wireless Power Transmitter for Unipolar and Bipolar Receiving Coils Based on Three-Switch Dual-Output Inverter

An Interoperable Wireless Power Transmitter for Unipolar and Bipolar Receiving Coils Based on Three-Switch Dual-Output Inverter

Thermal stability of triple-junction gallium arsenide cells.

Laser wireless power transmission (LWPT) systems have significant applications in the field of wireless energy transmission, including spacecraft sensor networks, satellite-to-satellite communication, and remote power supply. However, continuous laser exposure increases the temperature of the photovoltaic (PV) cells in the LWPT system, thus decreasing the electrical output performance. This work, which we believe is a new approach, is on the basis of a notch film designed by a combined merit function proposed to maintain the electrical output performance while under 1064-nm continuous laser irradiation. Moreover, the thermal stability of PV cells under laser irradiation was investigated, which revealed the recoverability of the open-circuit voltage (Voc) of the cells at different temperatures, and the thermal damage to cells was a gradual process. This process began with the vaporization of the encapsulation adhesive, followed by a decline in, but still recoverable and functional, electrical performance, and finally, the cell was completely damaged. The thermal stability of the PV cells coated with the notch film increased ten-fold compared to those without it. Furthermore, the correlation between the minimum Voc and maximum temperature of the cells with notch films of different performances was established. These investigations serve as references for further optimization of LWPT.

Dual‐Function Microwave Devices Based on Metamaterials

AbstractMicrowave detectors play a crucial role in modern technological applications, but traditional detectors suffer from limited functionality, limited detection accuracy, and difficulties in large‐scale deployment. This study proposes a dual‐function microwave detector based on metamaterials, capable of simultaneously measuring microwave power and polarization angle. The detector consists of a metal disc with 12 concave grooves, a dielectric layer, a metal reflector, and a resistive network. The designed detector achieves efficient absorption of 93.54% of microwave energy, with 75.4% dissipated in the resistive component and converted into heat. By detecting the temperature using a thermocouple thermometer, the incoming wave power can be determined, and by discriminating between different resistive temperatures, the polarization angle of the incoming wave can be identified. Simulation and experimental results demonstrate the outstanding detection efficiency and stability of this detector. It exhibits a linear response to different incident power densities and polarization angles, showing potential application value in the field of microwave wireless power transmission.

A Self‐Powered Reconfigurable Intelligent Metasurface

AbstractIn recent years, reconfigurable intelligent metasurface (RIS) has gained much attention due to its flexibility in modulating the phase, amplitude, and polarization of electromagnetic waves. It is widely used for wireless power and information transmission. However, RIS requires an external wired power supply or batteries to activate their modulation capabilities, as they do not generate the required energy themselves. This paper presents a self‐powered RIS that does not require an external wired power supply or batteries. The modulation capability is activated by harvesting radio frequency (RF) energy. The self‐powered RIS consists of an energy‐metatom, which is loaded with a PIN diode for flexible phase modulation. The inclusion of an absorber/energy port on the energy‐metatom allows for independent RF energy harvesting. The RIS consisting of energy‐metatoms can cut out all wired power supplies and batteries so that it can dynamically regulate electromagnetic waves by self‐powered means. As a proof‐of‐concept, a prototype composed of 10 × 10 energy‐metatoms is fabricated. The measured results are in good agreement with the simulated. This self‐powered RIS can be used as an “infinite‐lifetime” power supply for dynamic electromagnetic modulation in the RIS.

Research on Metal and Living Foreign Object Detection Method for Electric Vehicle Wireless Charging System

In the electric vehicle wireless power transmission system, the high-frequency alternating magnetic field between the transmitter and receiver can have a certain impact on the health of living organisms and may even lead to lesions. In addition, metal foreign objects in an alternating magnetic field can cause their own heating or even cause fires due to the eddy current effect, so foreign object detection is an essential function in the wireless power transmission system of electric vehicles. In order to prevent metals and living organisms from entering the charging area and causing harm to the charging system and living organisms, this paper proposes a method for detecting living organisms and metal foreign objects. Firstly, the equivalent circuits for the detection systems of the living organism foreign objects and metal foreign objects are established, respectively, and the working theory of the detection system is analyzed by deriving equations. Secondly, the comb capacitor simulation model was constructed, and the comb capacitor electrode spacing, wire thickness, and capacitor spacing were designed based on the scale factor γ to explore the effects of the height and bottom area of the living organism’s foreign object on the comb capacitor. We constructed a simulation model of the detection coil and designed the inner diameter D, the number of turns N, and the wire spacing S of the detection coil according to the scale factor β. An arrayed detection coil and comb capacitor combination mode is proposed to realize the function of the simultaneous detection of metal and living organism foreign objects, and a compensation capacitor is introduced to keep the detection system in a resonant state. Lastly, a platform for foreign object detection experiments was set up to detect metal screws and beef chunks compared to the detection area without foreign objects. Metal screws entering the detection area cause a 20% voltage drop in the detection circuit resistor, and beef chunks entering the detection area cause a 30% voltage drop in the detection circuit resistor, so the detection method is effective in detecting both metals and living organisms. The feasibility of the combined mode of arrayed detection coils and comb capacitors was verified.

Stable dynamic wireless power transfer via a space-extendable high-order Non-Hermitian system

A prominent problem in wireless power transmission systems is the sensitivity of the mode frequency to changes in position. While a feedback system can address this issue, it also introduces complexity to the system, potentially giving rise to additional problems. Typically, more complex systems exhibit unique properties, and there are modes suitable for power transfer in high-order PT systems.In this paper, we propose a dynamic wireless power transmission system with hybrid coupling, utilizing odd coils only. This approach offers a feasible solution for dynamic wireless power transmission systems. We calculate the eigenvalues of the system and observe that the eigenvalue of a mode does not change as the load moves, remaining a pure real number. In our study, the system’s transmission efficiency can be maintained at a high and stable level at a fixed working frequency, even as the load position changes. This capability can be employed for stable dynamic charging.

Capacitive-Coupling-Responsive Hydrogel Scaffolds Offering Wireless In Situ Electrical Stimulation Promotes Nerve Regeneration.

Electrical stimulation (ES) has shown beneficial effects in repairing injured tissues. However, current ES techniques that use tissue-traversing leads and bulky external power suppliers have significant limitations in translational medicine. Hence, exploring noninvasive in vivo ES to provide controllable electrical cues in tissue engineering is an imminent necessity. Herein, a conductive hydrogel with in situ electrical generation capability as a biodegradable regeneration scaffold and wireless ES platform for spinal cord injury (SCI) repair is demonstrated. When a soft insulated metal plate is placed on top of the injury site as a wireless power transmitter, the conductive hydrogel implanted at the injury site can serve as a wireless power receiver, and the capacitive coupling between the receiver and transmitter can generate an alternating current in the hydrogel scaffold owing to electrostatic induction effect. In a complete transection model of SCI rats, the implanted conductive hydrogels with capacitive-coupling in situ ES enhance functional recovery and neural tissue repair by promoting remyelination, accelerating axon regeneration, and facilitating endogenous neural stem cell differentiation. This facile wireless-powered electroactive-hydrogel strategy thus offers on-demand in vivo ES with an adjustable timeline, duration, and strength and holds great promise in translational medicine.

Increasing the robustness of electrodynamic WPT systems with hybrid electromechanical transduction

In this paper, we compare the electrical damping capability of low-frequency electrodynamic wireless power transmission (EWPT) systems based on a resonant electromechanical receiver in the context of increasing their mechanical robustness. This study is carried out for piezoelectric (PE) and electrodynamic (ED) transducers. The receiver studied, excited by a distant transmitter coil, consists of a magnet and a resonant cantilever beam, and both ED and PE transducers (hybrid system). A strategy based on dual energy conversion is proposed that takes advantage of each transduction characteristic: the receiver with high-quality-factor is sufficiently sensitive to very weak excitation fields far from the transmitter, while it is robust to strong magnetic fields close to the transmitter by damping its motion. This approach is particularly relevant to increase the robustness of resonant receivers powering moving sensor nodes as the field strength seen by the receiver can vary greatly. This paper aims to evaluate three energy transduction strategies (PE-only, ED-only and hybrid) to both harvest more power and increase EWPT systems robustness by overdamping. An analytical model of the system is presented along with comparison with experimental results from a 71.7 cm3 prototype. When the motion amplitude is limited to 0.7 mm to limit aging, the receiver output 19 mW which outperforms the PE and ED modes alone by a factor of 1.5 and 1.8, respectively. Furthermore, the hybrid receiver can limit the amplitude of motion to 0.7 mm under a magnetic field up to 3.6 mT, which is 2.5 and 1.2 times higher than PE and ED alone, respectively.

Self-image-guided ultrasonic transceiver design for reliably powering mm-sized implants

This paper presents the design of a self-image-guided ultrasonic (SIG-US) transceiver for reliable wireless power transmission (WPT) to miniaturized biomedical implants. In the receiver (RX) mode, this paper proposes a method for high precision time interval measurement (TIM) between two signals independent of their amplitudes. In the transmitter (TX) mode, a 15 V Class-DE driver by stacking 3.3 V transistors of 180 nm standard CMOS technology is designed to drive a 32-element linear array. The designed TX efficiency is 90.93%. The post-layout and the Matlab k-Wave toolbox simulation results show that the designed system is capable of transmitting power to the implant with less than 0.9% reduction compared to the ideal SIG-US system over the ±45° steering range. Considering the mismatch effect between transistors, the power reduction is less than 2% in the worst case. The RX with a power consumption of 628.83 μW from a nominal supply voltage of 1.8 V, is capable of detecting time delays between two signals over the input range of 1 mV to 10 mV, with high accuracy.

Dead-Time Effect in Inverters on Wireless Power Transfer

This paper presents a comprehensive analysis of the dead-time effects in wireless power transfer systems based on LCC-S topology. In these systems operating at high frequencies, the ratio of dead-time versus the operating period becomes critical, and the dead-time issue can cause certain problems regarding power quality, efficiency, and output voltage ripple. The impact of input quantities such as voltage and switching frequency on the efficiency and output power of the LCC-S-tuned WPT system was also investigated. The optimal combination of these parameters used to achieve the maximum efficiency for a target output power and to set the appropriate value of the dead time were determined by running multiple simulations using the MATLAB R2023b software platform. It was also shown that the output voltage remained unchanged with and without a load and up to 1200 ns of dead-time, which provides a simple implementation of the corresponding mathematical model. In the recommended interval of 600–1500 ns, the influence of the dead-time on the value of the output voltage amplitude is less than 10%. The validity of the proposed method was confirmed through the implementation of the experimental prototype, a 5 kW wireless power transmission system, and the obtained results were in accordance with the simulation results.

Analysis of a transformer designed for wireless power transmission system for different distance and alignment conditions and optimization with a developed algorithm

Analysis of a transformer designed for wireless power transmission system for different distance and alignment conditions and optimization with a developed algorithm

Mirror Symmetry Coils for Foreign Object Detection and Location with Wireless Power Transmission

Background: Wireless power transmission technology effectively avoids safety issues caused by accidental contact, wire aging, and friction. However, due to the presence of foreign objects, other severe accidents such as fire hazard can occur, and the charging system can be interfered with and even damaged by the foreign objects. background: As a new charging technology, the wireless power transmission (WPT) technology has shown some favorable application prospects on safety, reliability, and convenience. Method: Therefore, this paper proposes (MSD) mirror symmetry detection coils to detect and locate foreign objects. First, we conduct theoretical analysis and derive formulas to validate our proposed method. Next, we employ ANSYS Maxwell to simulate the (WPT) wireless power transmission system, considering various sizes and materials of foreign objects and comparing them to a system without foreign objects. Result: Furthermore, we conducted experiments using mirror symmetrical detection coils to detect and locate foreign objects, providing additional verification for our proposed method. Conclusion: The simulation and experimental results show that the proposed method of mirror symmetry detection coils can effectively identify and locate the foreign objects.

A Flexible Wireless Sacral Nerve Stimulator Based on Parity–Time Symmetry Condition

Lower urinary tract dysfunction (LUTD) has a great effect on patients’ daily life and mental health. Currently, the most mature invasive treatment is sacral neuromodulation (SNM) that needs to be implanted into buttocks and work for 1–2 years. However, most existing SNM stimulators use disposable batteries with a limited lifespan. And existing stimulators are rigid and lack biomechanical compatibility. To address the above problems, wireless power transferring (WPT) is proposed for SNM based on parity–time (PT) symmetry principle to meet buttocks application requirements, where has thick fat and skin tissue. The receiver coil in the SNM stimulator is designed to be as small and flexible as possible to fit implantation. PT technology allows for efficient and stable wireless power transmission without being significantly affected by the misalignment and bending caused by body movement and can penetrate 15 mm fat–skin tissue and achieve 78% transmission efficiency. Furthermore, the flexible wireless sacral nerve stimulator is developed, and the effectiveness of the system is verified. The system could potentially reduce patient discomfort because the implanted device is flexible and can output a stable voltage stimulation signal.