A cooperative control of wireless power transfer system using two transmitters

In this paper, we first proposed a novel hybrid loop array (HLA) for low leakage electromagnetic field (EMF) level and high efficiency in a wireless high power transfer system. The proposed HLA effectively enhances the system efficiency and shields leakage EMF in a wireless power transfer (WPT) system using kHz range resonant frequency. The key originality of the proposed HLA is the combination of two types of loop coil; shielding loop coil (SLC) and amplifying loop coil (ALC). SLCs reduce leakage EMF, and ALCs significantly enhance the magnetic field from a Tx coil. The simulation and experiment results show that the proposed solution successfully overcomes the limitations of the existing solutions. Analytical modeling and design procedure are introduced and discussed. In addition, the experimental verification of the simulation result is included. We first designed and modeled an HLA considering the coupling effect of neighboring loop coils to evaluate its efficiency and leakage EMF. With the proposed HLA, we demonstrated a 9.36% improvement in the efficiency and 3 dBm reduction in the leakage EMF near the WPT system.

This paper investigated coexistence possibility of high efficiency Wireless Power Transfer (WPT) system and high-speed communication system in Short-range Wireless Communication and Power Transfer (WiCoPT) system. To realize both high power transfer efficiency and high data rate, this paper proposes the WiCoPT system, which is supported by the Short-Range Multiple Input and Multiple Output (SR-MIMO) transfer technique. Relationship between the antenna element spacing and the transmission performance was analyzed to clarify the maximum performances of the power transfer efficiency and the data rate. The paper analyzed and demonstrated a 4×4 MIMO WiCoPT system. The numerical analysis indicates that the antenna element spacing to maximize the power transfer efficiency is different from that to realize the highest channel capacity. In addition, the analysis clarifies there are two suitable antenna element spacing for high power transfer operation. Therefore, our proposing system chose the antenna element spacing to realize the second peak for the high-level power transfer efficiency simultaneously. The 4×4 MIMO WiCoPT system achieved a channel capacity of 45 bit/s/Hz and a power transfer efficiency of 64.8 %.

The cyber-physical system such as wireless information and wireless power (WIPT) transfer plays an important role in the internet of things (IoT) applications. The billions of smart objects and devices are connected to the global IoT platform. To get benefit from the IoT technology, smart customers and system operators demand to supply wireless power wireless for making electronic things alive. In this way, the IoT can make greener and smart city with an interconnected digital platforms. However, it is a very difficult and challenging task for supplying wireless power to the smart objects. In order to provide wireless power to the IoT enabled devices, the wireless power transfer system can play a vital role for providing greener and sustainable environment. In light of this demand, this paper provides a comprehensive literature review and potential research challenges for WIPT incorporating wireless power transfer (WPT) system. In order to supply energy to the devices, the electricity generating electronics circuit requires to know the operating conditions of the system state, which acts as a precursor to design the controller. To know the system operating conditions of wireless power transfer system, the distributed state estimation algorithm is proposed and it convergence is analysed. Finally, the proposed algorithm is verified considering the WPT system. For doing this, the state-space framework of the WPT system is developed. Numerical simulations results show that the proposed algorithms can able to estimate and stabilise the WPT system states within a short period of time. Therefore, this framework is valuable to design WIPT and IoT platform and provide a compressive of source for researchers.

Underwater wireless power transfer (UWPT) system has attracted widespread attention. It has been used for power delivery for underwater equipment in the marine environment with high safety and convenience. However, the material of metal plates and the shape which will affect the high frequency alternating electromagnetic fields and the high frequency alternating electric fields for the inductive wireless power transfer (IPT) system and the capacitive wireless power transfer (CPT) system. This paper presents the effects of the hull of the autonomous underwater vehicle (AUV) on the underwater wireless power transfer system including the underwater capacitive wireless power transfer (UCWPT) system and underwater inductive wireless power transfer (UIWPT) system. The features of underwater wireless power transfer systems have been carefully studied with simulation and experimental work. The experimental water tank has been constructed with the 35‰ salinity water. The hull of AUVs has been respectively simulated and built with rectangle metal plates and curved metal plates. The original experimental data and phenomenon have been presented in this paper. The different performance of the UCWPT system and UIWPT system is provided and discussed in this paper. The comparison work with the related paper has been analyzed. This paper could be acted as the reference for designing the underwater wireless power transfer system for AUVs.

Wireless Power Transfer (WPT) systems are considered as sophisticated alternatives for modern day wired power transmission. Resonance based wireless power delivery is an efficient technique to transfer power over a relatively long distance. This paper presents a summary of a two-coil wireless power transfer system with the design theory, detailed formulations and simulation results using the coupled mode theory (CMT). Further by using the same theory, it explains the four-coil wireless power transfer system and its comparison with the two-coil wireless transfer power system. A four-coil energy transfer system can be optimized to provide maximum efficiency at a given operating distance. Design steps to obtain an efficient power transfer system are presented and a design example is provided. Further, the concept of relay is described and how relay effect can allow more distant and flexible energy transmission is shown.

This paper presents an approach for concurrent power transfer to wired and wireless systems using just a single inverter. The approach utilizes a novel carrier phase-shift (CPS) method that independently controls the inverter output voltages at the fundamental and switching frequencies. This proposed method can be a cost-effective solution to wireless power transfer (WPT) systems used in contactless slip rings (CSR), which transfer power to auxiliary loads such as sensors, radars, and IoT devices. There are two separate converters in conventional CSR systems: one is for the motor drive, and the other is for the WPT system. It is proposed that the switching harmonics of the motor drive can also be utilized to excite the WPT system while the low-frequency component can still be used to drive the motor. In order to control these independently, the CPS method is introduced. The proposed method is investigated analytically for sinusoidal-PWM (SPWM). Then, an experimental setup consisting of a 3-phase 3-wire GaN-based inverter and a 3-phase motor is built. Experimental results show that the WPT and motor systems are operated concurrently, and their powers are controlled independently by the proposed method.

High-efficiency medium-range wireless power transfer using magnetically coupled resonators requires a wireless data link between the contactless coils to regulate power. Multiplexing the power transfer channel as the information channel is a cost-effective solution for the communication. However, existing technologies cannot transmit data across the medium-range magnetically coupled resonators channel without substantially affecting power transfer. Here we show a power-electronics-converters based wireless power and information dual transfer system in which the information signals are modulated on one dc side of the inverter/rectifier, and transmitted through a conventional medium-range wireless power transfer system, and then demodulated on the other dc side. Using the frequency mixer characteristic of the inverter/rectifier, information is modulated onto the sideband of the power carrier and transmitted through the medium-range channel. Finally, we prototyped a 6.78 MHz system capable of transferring 45 W power across a one-meter distance with 62% efficiency and 60 kb/s bitrate for half-duplex communication.

This paper is proposed the efficiency improvement in wireless power transfer system is applied sensor device in IoT system. The study and design of the metamaterials structure to be applied with antennas in wireless power transfer (WPT) system at 2.45 GHz (ISM band) are performed to improved efficiency of power transfer. The two types of metamaterial are applied to the wireless power transfer. 1)The Artificial Magnetic Conductor (AMC) type, it is designed to be placed behind the antenna of transmission part. The Microstrip antenna is used in this paper. This AMC is use as the in-phase reflector to increase radiation intensity and efficiency of the transmit antenna. 2) Metamaterials structure type of Multiple Split-Ring Resonators (MSRR) that have negative refraction index is placed between the transmit antenna and the receiving antenna. This feature of the structure reduces the evanescence of the electromagnetic wave. From the results, it is found that the metamaterials can be optimized for both antennas in a wireless power transfer system at 2.45 GHz and improved the efficiency of wireless power transfer system

This paper introduces the first reported electrically small Huygens dual-functional wireless power transfer (WPT) and communication system operating in the 915-MHz ISM band. It is realized by the seamless combination of a Huygens linearly polarized (HLP) antenna and a highly efficient HLP rectenna. The configuration consists of two orthogonally oriented HLP subsystems. Each one intrinsically combines two pairs of metamaterial-inspired near-field resonant parasitic elements, i.e., an Egyptian axe dipole (EAD) and a capacitively loaded loop (CLL). Through the development of a very tightly coupled feed subsystem that includes the WPT mode's rectifier circuit and the communications mode's feedline while preserving their isolation, the independent operation of both functions is facilitated in an electrically small volume (ka <; 0.77). The measured results of its fabricated prototype agree well with their simulated values. The communications mode antenna resonates at 910 MHz and radiates a cardioid-shaped Huygens pattern with the peak gain of 2.7 dBi. The Huygens-based WPT rectenna achieves an 87.2% peak ac-to-dc conversion efficiency at 907 MHz. The dual-functional system is an ideal candidate for many emerging Internetof-Things (IoT) wireless applications that require simultaneous wireless information and power transfer (SWIPT) and wirelessly powered communications (WPC).

The wireless power transfer systems are very often used to charge high-tech devices nowadays. To obtain a high performances wireless system it must be properly designed in order to have a power transfer from the emitter to the receiver as higher as possible taking into consideration all the specifications and parameters of the devices for which it is construct. This paper presents a way to optimize a wireless inductive power transfer system for the charging device. The physical limitations of the application require that the coils and electronic circuit be in optimal shape to maximize the output power delivered to the load and the power transmission efficiency of the wireless power system. The paper also includes numerical results for different working distances between the coils, ranging from 1 mm to 20 mm, and explores the response of the system at different frequencies.

This paper proposes a miniaturized fractal rectenna to address the demands of integration and small size in wireless communication and wireless power transfer (WPT) system. The miniaturized fractal antenna adopts a three-layer symmetric stacked structure, all fabricated by felt material that provide mechanical stability and electromagnetic isolation. The radiation patch layer uses a square patch with slots etched at the centers of its four sides to optimize miniaturization and radiation performance; the transmission line layer employs two vertically placed parallel lines to enhance electromagnetic coupling attenuation and reduce port crosstalk; the ground layer uses a PEC plate matching the substrate size to ensure good grounding and electromagnetic shielding. For the WPT system, a rectifier is integrated to convert the AC power received by the antenna into usable DC power. In terms of performance, the antenna with two ports both resonates at 2.45 GHz, with a high-gain of 3.8 dBi and 3.8 dBi; the integrated WPT system effectively achieves power reception and conversion via the rectenna, enabling 65% conversion efficiency. This miniaturized fractal rectenna can potentially provide structural design references and performance data support in wireless communication fields (e.g., small-scale IoT devices, portable communication terminals) and low-power SWIPT scenarios (e.g., wirelessly powered sensors, wearable electronic devices).

To ensure electric energy supply at arbitrary directions, omnidirectional Wireless Power Transfer (WPT) system is gaining increasing attention. The cubic structure with three orthogonal coils is becoming one of the optimal technical solutions for omnidirectional WPT system. In this paper, the transfer characteristics, such as load resistance changing and coupling coefficient changing, of a three-transmitter and three-receiver WPT system are analyzed and compared with those of a conventional single-transmitter and single-receiver WPT system. According to the electric circuit theory and 1:1 WPT system model, the theoretical model of M:N WPT system is derived and generalized. And then, a set of 3D orthogonal coils is designed and trial-manufactured for testing the transfer characteristics of the 3:3 WPT system. At last, an experimental platform is built up to test and compare the transfer characteristics of both 1:1 and 3:3 WPT systems. The tested results show that the theoretical analysis is correct and the maximal transmission power is 150W and the maximal transmission efficiency is 43.6% when the 3:3 WPT distance is 20cm. Furthermore, the designed 3:3 WPT system can realize full-space energy transmission for electronic equipment and the output stability can maintain high when the coil spatial offset occurs.

Wireless power transfer (WPT) has garnered significant interest as a potentially transformative technology in the energy sector, as it presents a novel approach to powering and charging devices. The functionality of this technology is predicated upon the utilization of electromagnetic coupling to facilitate the wireless transmission of energy between two entities. Despite the considerable potential, wireless power transfer (WPT) faces significant obstacles that restrict its practical feasibility. One notable challenge that arises is the decrease in power transfer efficiency as the distance between the transmitter and receiver increases. Moreover, the wireless power transfer (WPT) technology is further limited by its reliance on accurate alignment between the transmitting source and the receiving device, thereby posing challenges for its practical implementation. The issues present substantial obstacles to the widespread commercialization of wireless power transfer (WPT). This study seeks to improve the efficacy of power transfer by optimizing the resonance frequency of the power transfer in response to the challenges. By systematically manipulating various parameters including coil dimensions, input voltage levels, and operational frequency, a novel approach is proposed to enhance the efficiency of power transfer. The study additionally offers valuable insights regarding the correlation between the distance separating the coils and the efficiency of power transfer. The findings of this study offer a thorough empirical analysis and are supported by a strong theoretical framework, resulting in a substantial coefficient of determination (R2 = 0.937118). This finding suggests that the linear regression model under consideration could account for approximately 93.7118 percent of the variability observed in the distance. The findings of this study establish a pathway toward enhanced and feasible wireless power technology, thereby establishing a robust basis for the prospective commercial implementation of wireless power transfer (WPT) systems.

Inductively coupled resonant wireless power transfer (WPT) systems can be used as a wireless power and information transfer (WPIT) system by properly adding the function of varying Rx loads. A new metric for the figure of merit for information transfer from Rx to Tx is proposed as the ratio of Tx input impedances for the Rx shorted and optimum loads to systematically assess the information transfer. While most of WPT and near-field communication (NFC) devices have been adopted for very short distances between Tx and Rx, this work shows that the WPIT systems using inductively coupled resonant structures with high Q-factor coils enable much longer working distances with the best power transfer efficiency and information transfer capability. Several design examples show that the newly proposed figure of merit for information transfer is an essential metric in the understanding and design of WPIT systems. The theory is validated with circuit and electromagnetic simulations for various system configurations.

This paper presents the design of a bidirectional wireless power and information transfer system. The wireless information transfer is based on near-field technology, utilizing communication coils integrated into power transfer coils. Compared with conventional far-field-based communication methods (e.g., Bluetooth and WLAN), the proposed near-field-based communication method provides a peer-to-peer feature, as well as lower latency, which enables the simple paring of a transmitter and a receiver for power transfer and the real-time updating of control parameters. Using the established communication, control parameters are transmitted from one side of the system to another side, and the co-control of the inverter and the active rectifier is realized. In addition, this work innovatively presents the communication-signal-based synchronization of an inverter and a rectifier, which requires no AC current sensing in the power path and no complex algorithm for stabilization, unlike conventional current-based synchronization methods. The proposed information and power transfer system was measured under different operating conditions, including aligned and misaligned positions, operating points with different charging powers, and forward and reverse power transfer. The results show that the presented prototype allows a bidirectional power transfer of up to 1.2 kW, and efficiency above 90% for the power ranges from 0.6 kW to 1.2 kW was obtained. Furthermore, the integrated communication is robust to the crosstalk from the power transfer and misalignment, and a zero BER (bit error rate) and ultra-low latency of 15.36 µs are achieved. The presented work thus provides a novel solution to the synchronization and real-time co-control of an active rectifier and an inverter in a wireless power transfer system, utilizing integrated near-field-based communication.