Showing papers on "Maximum power transfer theorem published in 2022"
TL;DR: In this paper , a two-stage algorithm is proposed to solve the above-mentioned problem by applying semidefinite relaxation (SDR), Gaussian randomization and successive convex approximation (SCA).
Abstract: This paper proposes a novel network framework of intelligent reflecting surface (IRS)-assisted simultaneous wireless information and power transfer (SWIPT) non-orthogonal multiple access (NOMA) networks, where IRS is used to enhance the NOMA performance and the wireless power transfer (WPT) efficiency of SWIPT. We formulate a problem of minimizing base station (BS) transmit power by jointly optimizing successive interference cancellation (SIC) decoding order, BS transmit beamforming vector, power splitting (PS) ratio and IRS phase shift while taking into account the quality-of-service (QoS) requirement and energy harvested threshold of each user. The formulated problem is non-convex optimization problem, which is difficult to solve it directly. Hence, a two-stage algorithm is proposed to solve the above-mentioned problem by applying semidefinite relaxation (SDR), Gaussian randomization and successive convex approximation (SCA). Specifically, after determining SIC decoding order by designing IRS phase shift in the first stage, we alternately optimize BS transmit beamforming vector, PS ratio, and IRS phase shift to minimize the BS transmit power. Numerical results validate the effectiveness of our proposed optimization algorithm in reducing BS transmit power compared to other baseline algorithms. Meanwhile, compared with non-IRS-assisted network, the IRS-assisted SWIPT NOMA network can decrease BS transmit power by 51.13%.
43 citations
TL;DR: The classification and types of UAVs, as well as various battery charging methods, are discussed in this paper, and a number of difficulties and solutions for safe operation are addressed.
Abstract: The groundbreaking Unmanned Aerial Vehicles (UAVs) technology has gained significant attention from both academia and industrial experts due to several applications, such as military missions, power lines inspection, precision agriculture, remote sensing, delivery services, traffic monitoring and many more. UAVs are expected to become a mainstream delivery element by 2040 to address the ever-increasing demand for delivery services. Similarly, UAV-assisted monitoring approaches will automate the inspection process, lowering mission costs, increasing access to remote locations and saving time and energy. Despite the fact that unmanned aerial vehicles (UAVs) are gaining popularity in both military and civilian applications, they have a number of limitations and critical problems that must be addressed in order for missions to be effective. One of the most difficult and time-consuming tasks is charging UAVs. UAVs’ mission length and travel distance are constrained by their low battery endurance. There is a need to study multi-UAV charging systems to overcome battery capacity limitations, allowing UAVs to be used for a variety of services while saving time and human resources. Wired and Wireless Power Transfer (WPT) systems have emerged as viable options to successfully solve this difficulty. In the past, several research surveys have focused on crucial aspects of wireless UAV charging. In this review, we have also examined the most emerging charging techniques for UAVs such as laser power transfer (LPT), distributed laser charging (DLC), simultaneous wireless information and power transfer (SWIPT) and simultaneous light wave information and power transfer (SLIPT). The classification and types of UAVs, as well as various battery charging methods, are all discussed in this paper. We’ve also addressed a number of difficulties and solutions for safe operation. In the final section, we have briefly discussed future research directions.
38 citations
TL;DR: A smart detection algorithm for identifying the positioning and orientation of receiver devices based on the input power information is presented and a novel power flow control with a load combination strategy to charge multiple loads simultaneously is explained.
Abstract: This article presents a control scheme for an omnidirectional wireless power transfer system. A system architecture is proposed to implement the current amplitude control. To focus power transfer towards targeted loads, a smart detection algorithm for identifying the positioning and orientation of receiver devices based on the input power information is presented. The system efficiency is further improved by a maximum efficiency point tracking function. A novel power flow control with a load combination strategy to charge multiple loads simultaneously is explained. Finally, the proposed control scheme is successfully applied to an example 6.78 MHz omnidirectional wireless charging bowl system. The experimental results confirm the accuracy of the load detection algorithm and validate the power flow control strategy.
25 citations
TL;DR: In this article, a parameter optimization method is proposed for the electrical field resonance-based six-plate coupler system, where the ratio of the reactive power in the compensation network to the system transferred power is set as the main optimization goal.
Abstract: Wireless power transfer (WPT) is more convenient and safer than conductive charging for power consumer electronics, biomedical devices, transportation systems, etc. Inductive power transfer is the most widely studied and commercialized WPT technique; however, capacitive power transfer (CPT) is becoming an attractive alternative, offering better misalignment tolerance and lower cost and weight. The electrical-field-resonance-based six-plate coupler system is one of the most typical configurations for high-performance CPT systems, but the associated large number of circuit parameters is always a critical issue for system design. In this article, a parameter optimization method is proposed for this topology. The ratio of the reactive power in the compensation network to the system transferred power is set as the main optimization goal. To solve the high-order optimization problem, a two-stage method is proposed to significantly reduce the optimization complexity while providing the optimized parameters of the whole system. To verify the effectiveness of this method, a 3-kW, 1-MHz CPT system with a 16-pF coupling capacitor is built. Both the simulation and experimental results show that the optimized parameters effectively improve the system efficiency, experimentally achieving 95.7% dc–dc overall efficiency under a 100-mm gap distance at the rated power.
24 citations
TL;DR: In this article , a compensation design method for achieving the maximum power of CPT systems under coupling voltage constraints is proposed, based on a simplified capacitive coupling model and thorough power transfer characteristics analysis, a family of compensation topologies are derived to maintain a 90° phase shift between the input and output voltages across the CPT coupler against load variations.
Abstract: It is well known that a high voltage across the coupling plates of a capacitive power transfer (CPT) system is beneficial to increase its power transfer capability, but a high voltage may lead to high insulation requirements and cause safety concerns. This article proposes a compensation design method for achieving the maximum power of CPT systems under coupling voltage constraints. Based on a simplified capacitive coupling model and thorough power transfer characteristics analysis, a family of compensation topologies are derived to maintain a 90° phase shift between the input and output voltages across the CPT coupler against load variations, so that the coupling voltages (which practically need to be limited) are fully utilized for power transfer purposes. A full design process for determining the compensation parameters is presented, and an example 2-kW CPT system is built and tested using LC compensation at the primary side to boost the input voltage to the coupler; and one of the proposed compensation topologies (CLC) at the secondary side for impedance transformation of a given load with a specified voltage and power requirements. Experimental results show a good agreement with theoretical analysis, which demonstrate the phase difference between the voltages before and after the coupler is kept nearly 90°, and a maximum possible power transfer of 2.039 kW is achieved under the given voltage limits and coupling conditions. A system end-to-end (dc–dc) efficiency of 90.29% is obtained when the air gap between the coupling plates is 150 mm, and the coupling capacitance is only 13.84 pF.
24 citations
TL;DR: In this paper , a genetic algorithm was used to optimize the side lengths of the transmitting and receiving coils of the Tx and Rx coils, respectively, to achieve better coupling performance in different misalignment situations.
Abstract: The misalignment between the transmitting (Tx) coil and the receiving (Rx) coil is an urgent problem in the drone charging system using wireless power transfer technology. The coupling coefficient is so low when the resonance coils is not aligned, which degrades the drone wireless charging performance. In this article, the optimization processes of the coupling mechanism are presented in detail. First, we illustrate the great superiority of unequally spaced Tx coil, compared with traditional uniformly spaced one. Then, a genetic algorithm to optimize the side lengths of the Tx coils is highlighted by discussing the main design considerations and methods in a comprehensive manner. Furthermore, the Rx coil with varying radius size per turn is proposed in terms of the distribution of magnetic field generated by the optimized Tx coil. Experimental results show that the optimized coils have better coupling performance due to small mutual inductance change under the condition of misalignment. Power transfer efficiencies in different misalignment situations are measured and the best power transfer efficiency improvement achieved by the proposed system can reach 56.23% in contrast with traditional coils. This drone charging system can transfer a maximum power of 100 W with the remarkable transfer efficiency of 92.41%.
23 citations
TL;DR: The outcome shows how the introduced energy harvesting technique manages to improve EE and SE compared with the conventional cooperative networks of the recent related work by 70%.
Abstract: In this paper, cooperative simultaneous wireless information and power transfer terahertz (THz)-nonorthogonal multiple access (NOMA) is considered to overcome the challenging shortages that THz communications have due to THz characteristics. The proposed system presents a noticeable improvement in energy efficiency (EE) and spectral efficiency (SE), in addition to other important metrics. By utilizing NOMA technology and THz frequencies, it aims to improve connectivity, resource management, SE, reliability, scalability, user fairness, and to enhance the overall performance of wireless communications. Accordingly, the outcome shows how the introduced energy harvesting technique manages to improve EE and SE compared with the conventional cooperative networks of the recent related work (e.g., cooperative MIMO-NOMA with THz) by 70%. The author also minimizes the transmission power and maximizes the EE by using a decode-and-forward relay rather than an intelligent reflecting surface, which aims to reduce the dissipation in the transceiver hardware, computational complexity, and improves reliability and transmission rate.
22 citations
TL;DR: In this article , a hybrid modulation control strategy based on a proper selection between the full-bridge and half-bridge modes of the inverter and active rectifier is developed, which can reduce the reactive power, maintain a constant output voltage, and realize the maximum system efficiency point (MEPT), with high efficiencies up to 94.29% in a wide load range.
Abstract: Traditional wireless power transfer (WPT) systems usually adopt the triple-phase-shift control method to maintain a constant output voltage, track the maximum system efficiency point (MEPT), and achieve zero-voltage-switching (ZVS) operation for various applications. However, these three targets are achieved at the cost of high reactive power on both primary and secondary sides, especially under light-load conditions, leading to low efficiency. This has become one of the challenges that hinder a further deployment of WPT technologies in practice. To address this vital problem, in this article, how the reactive power lowers the system efficiency is revealed based on a mathematical model established. Then, a hybrid modulation control strategy based on a proper selection between the full-bridge and half-bridge modes of the inverter and active rectifier is developed. An experimental prototype is constructed to verify the effectiveness of the proposed control method. Experimental results show that the proposed method can reduce the reactive power, maintain a constant output voltage, and realize the MEPT and ZVS operation, with high efficiencies up to 94.29% in a wide load range.
22 citations
TL;DR: In this article , the authors proposed a new transmission policy for intelligent reflecting surface (IRS) empowered wireless powered internet of things systems, where an energy station (ES) wirelessly charges for multiple IoT devices during downlink wireless energy transfer and then these devices deliver their own message to an access point (AP) during uplink wireless information transfer.
Abstract: This paper proposes a new transmission policy for intelligent reflecting surface (IRS) empowered wireless powered internet of things systems. Particularly, an energy station (ES) wirelessly charges for multiple IoT devices during downlink wireless energy transfer (WET) and then these devices deliver their own message to an access point (AP) during uplink wireless information transfer (WIT). Also, an IRS is deployed to improve energy harvesting and data transmission capabilities. To enhance self-sustainability of the IRS, the IRS harvests energy from the ES based on the harvest-then-transmit protocol. In this paper, we maximize the sum throughput via optimizing the phase shifts of the IRS, the transfer time scheduling as well as the power splitting ratio. Due to the non-convexity of the formulated problem, we divide the problem into two sub-problems, each of which can be handled separately. Then, we adopt an alternating optimization (AO) algorithm with the semidefinite programming (SDP) relaxation. Also, we consider a special case where the circuit power consumption of IoT devices can be neglected. In this case, we derive a closed form solution for the optimal transmission time slots, power allocation and phase shift by the Lagrange dual method. Finally, numerical evaluations validate effectiveness of the proposed scheme, which significantly benefits from the IRS in improving network throughput.
21 citations
TL;DR: This letter proposes a robust beamforming design to minimize the total transmit power by jointly optimizing the transmit beamforming and phase shifts of IRS subject to the outage rate probability constraints.
Abstract: In this letter, we study intelligent reflecting surface (IRS) aided simultaneous wireless information and power transfer (SWIPT) terahertz secure systems under a non-linear energy harvesting (EH) model. Assuming that the cascaded channel state information is imperfect, we propose a robust beamforming design to minimize the total transmit power by jointly optimizing the transmit beamforming and phase shifts of IRS subject to the outage rate probability constraints. We first transform the outage constraints into deterministic forms by using the Bernstein-type inequality. Then, we applying semidefinite programming to change the original non-convex problem into an equivalent convex problem, and develope an alternate iterative optimization algorithm to obtain a feasible solution of the original problem. Finally, simulation results validate the effectiveness of our proposed scheme.
21 citations
TL;DR: In this article , an arc-shaped underwater wireless power transfer magnetic coupler is proposed, which is suitable for AUV's curved shell and utilizes Fe-based nanocrystalline alloy soft magnetic material as the magnetic core.
Abstract: The underwater wireless power transfer (UWPT) technology provides a feasible way to solve the problems of the traditional power supply method of the autonomous underwater vehicle (AUV). The magnetic coupler is the most essential component in the wireless power transfer system. Its configuration determines its applicable scenarios, and its parameter design and optimization will directly affect the system's overall output power and efficiency. In this article, an arc-shaped underwater wireless power transfer magnetic coupler is proposed, which is suitable for AUV's curved shell. Especially, the proposed novel magnetic coupler utilizes Fe-based nanocrystalline alloy soft magnetic material as the magnetic core. Both volume and weight of the receiver are reduced compared with the traditional Mn-Zn ferrite material. Fe-based nanocrystalline alloy material provides a novel design idea for the magnetic coupler on electrical equipment with special-shaped shell due to its flexibility. A prototype of the UWPT system for 320 mm diameter AUV is built, and it can transfer 3 kW power in the experiment with a dc–dc efficiency of 91.9% at the forward maximum output power point. Compared with the structure with ferrite core, the volume of the proposed structure is reduced by 41.1%, and the weight is reduced by 42.6%, so that the expected effect has been achieved.
TL;DR: This review focuses on the recent advances in metamaterials (MMs) for simultaneous wireless information and power transmission (SWIPT) technology and introduces the potential technologies for SWIPT.
Abstract: Abstract In the last two decades, metamaterials and metasurfaces have introduced many new electromagnetic (EM) theory concepts and inspired contemporary design methodologies for EM devices and systems. This review focuses on the recent advances in metamaterials (MMs) for simultaneous wireless information and power transmission (SWIPT) technology. In the increasingly complex EM world, digital coding and programmable metamaterials and metasurfaces have enabled commercial opportunities with a broad impact on wireless communications and wireless power transfer. In this review, we first introduce the potential technologies for SWIPT. Then, it is followed by a comprehensive survey of various research efforts on metamaterial-based wireless information transmission (WIT), wireless power transmission (WPT), wireless energy harvesting (WEH) and SWIPT technologies. Finally, it is concluded with perspectives on the rapidly growing SWIPT requirement for 6G. This review is expected to provide researchers with insights into the trend and applications of metamaterial-based SWIPT technologies to stimulate future research in this emerging domain.
TL;DR: In this paper , a multiple-output capacitive power transfer (CPT) system using the inline-formula compensation network for low-power battery charging application, e.g., consumer electronics, is proposed.
Abstract: This article proposes a multiple-output capacitive power transfer (CPT) system using the $LCCL$ compensation network for low-power (< 20 W) battery charging application, e.g., consumer electronics. For CPT, reliable operation is still a challenge under a wide range of receiver configurations due to the variations in receiver position or load impedance. In this article, employing the constant-voltage property of the $LCCL$ network, the proposed multiple-output CPT system is able to achieve output independence among different receivers. Moreover, based on the first-harmonic approximation (FHA), a design method is proposed and studied in depth to maintain minimal current stress on power devices and inductors, as well as zero-voltage switching (ZVS) within a defined range. The proposed method considers the impact of component value ratios to limit the resonant current magnitude and determine the phase angle and selects inductance values for the most efficient system operation. Finally, a constructed 10-MHz experimental prototype achieves CPT from one transmitter to three independent 5-W receivers, with plate voltages less than 55 V. The measured power efficiency of the prototype is up to 83.6% at the 15-W output.
TL;DR: This article optimizes the parameters and shape of the cubic-magnetic coupler for inductive power transfer (IPT) system, which has huge application potential in the charging field of moving targets.
Abstract: This article proposes a kind of cubic-magnetic coupler (CMC) for inductive power transfer (IPT) system, which has huge application potential in the charging field of moving targets. The CMC can still maintain sufficient coupling coefficient when used for long-distance wireless power transfer, it also has great capability of misalignment tolerance. Distance-to-diameter ratio (DDR) is defined to eliminate the impact of coil size and make the comparison between different couplers fairer and easier. This article optimizes the parameters and shape of the CMC. Then, the proposed coupler is compared with several existing couplers employed in long-distance IPT systems. Double-sided LCC compensation topology is chosen to limit the current flowing through the coupling coils. A CMC with an outer size of 180×180×180 mm3 was made, based on which an IPT prototype was built. The superiorities of the proposed coupler were verified by a series of experiments. When the DDR equals 3, the coupling coefficient of the CMC is 0.00985, and the maximum dc–dc and ac–ac efficiencies are 64.9% and 72.8%, respectively.
TL;DR: In this paper , the authors reviewed the methods and techniques used for wireless charging in electric vehicles and compared the two main types of wireless charging: capacitive power transfer and inductive power transfer.
Abstract: Electric vehicles require fast, economical and reliable charging systems for efficient performance. Wireless charging systems remove the hassle to plug in the device to be charged when compared with the conventional wired charging systems. Moreover, wireless charging is considered to be environment and user friendly as the wires and mechanical connectors and related infrastructure are not required. This paper reviews the methods and techniques used for wireless charging in electric vehicles. First, the general techniques for wireless power transfer are described and explained. Capacitive power transfer and inductive power transfer which are the two main types of wireless charging are compared and contrasted. Next wireless charging systems for electric vehicles are classified and discussed in depth. Both the stationary and the dynamic wireless charging systems are discussed and reviewed. In addition, a typical model and design parameters of a dynamic charging system, which is a wireless charging system for moving vehicles, are examined. Control system functions of a wireless charging system of an electric vehicle are important for an effective and efficient performance. These are also discussed in the context of better efficiency of power transfer and improved communication between the transmitter and the receiver side of a vehicle charging system. Battery is an important part of an electric vehicle as different parameters of a charging system depend upon the battery characteristics. Therefore, different battery types are compared and battery models are reviewed. Findings of this state of the art review are discussed and recommendations for future research are also provided.
TL;DR: An improvement of SNR for SWPDT system with full-duplex communication mode with double-sided LCCL compensation topology and a novel data transmission based on the dual-resonant structure is proposed to suppress the ipsilateral interference.
Abstract: The power interference is always inevitable in the simultaneous wireless power and data transfer (SWPDT) system resulting in the lower signal to noise rate (SNR) and may cause the failure of communication. Besides, the interference between bidirectional data source is also the problem during the full-duplex communication. To solve these problems, in this article, an improvement of SNR for SWPDT system with full-duplex communication mode is proposed. In the power transfer channel, the double-sided LCCL compensation topology is selected due to its good performance of blocking the power interference on data transmission. Besides, the constant current characteristic of primary coil could guarantee the stability of power transmission. In the data transfer channel, a novel data transmission based on the dual-resonant structure is proposed to suppress the ipsilateral interference, and the full-duplex communication is achieved by two different frequencies. An optimization method of power and data transfer channel to improve SNR further is proposed after the analysis on interferences of power transmission and ipsilateral data source. Finally, the feasibility of proposed topology and the correctness of the parameter design method are verified by the simulation and experimental results.
TL;DR: In this paper, an extendable planar Tx-coil array architecture was proposed to achieve high spatial freedom of power transfer and compact and lightweight designs for MHz WPT systems.
Abstract: Wireless power transfer (WPT) systems operating at several MHz are known to be advantageous for realizing high spatial freedom of power transfer and compact and lightweight designs. The combined use of multiple transmitting (Tx) coils for magnetic field shaping is expected to further increase the spatial freedom. This article studies an extendable planar Tx-coil array architecture. This architecture provides new conveniences for the MHz WPT systems to efficiently charge devices in 3D space. Time-domain and phasor-domain modelings are carried out in turn to analyze the magnetic field shaping effect under the current phase shift modulation of the Tx coils. An overlap design of the Tx-coil layout is also developed to minimize the cross coupling between the coils, which reduces the interference between Tx coils. Finally, the above concepts are experimentally implemented. The results clearly demonstrate the new advantages of the planar Tx-coil array-based magnetic field shaping, in terms of spatial freedom of the power transfer, efficiency, and output power capability, when charging receivers with six-degrees-of-freedom positions and orientations in 3D space. For instance, a perpendicular receiver in the center of the Tx-coil array can be charged with 82% dc–dc efficiency and 45 W, which is difficult for a conventional single Tx-coil solution.
TL;DR: This work aims to maximize the system efficiency of a single-stage inductive power transfer (IPT) charger by minimizing the overall losses using a CP charging scheme and proposes a novel optimal control strategy to maintain CP output and maximum efficiency throughout the charging process.
Abstract: A typical battery charging process consists of a constant-current (CC) charging phase which is followed and completed by a constant-voltage charging phase. Moreover, replacing the CC charging by constant-power (CP) charging can eliminate thermal problems and enhance the cycle life of the battery. This work aims to maximize the system efficiency of a single-stage inductive power transfer (IPT) charger by minimizing the overall losses using a CP charging scheme. The single-stage CP IPT charger employs series-series compensation and adopts an active rectifier on the secondary side. Based on a time-domain model, the conditions of zero voltage switching (ZVS) and minimum circulating reactive power are derived. Then, the power losses in the magnetic coupler, inverter and active rectifier are analyzed and optimized under CP output condition. Combining the conditions of ZVS, minimum circulating reactive power, and minimum overall losses, we propose a novel optimal control strategy to maintain CP output and maximum efficiency throughout the charging process. In addition, the proportional integral controller is not needed. Finally, a 120-W experimental prototype is built to verify the performance of the proposed control strategy. Experimental results demonstrate high precision CP output and an efficiency of around 87.5 $\%$ for the proposed single-stage inductive power transfer battery charger.
01 Apr 2022
TL;DR: In this article , the authors provide a methodology to systematically construct suitable domino-type IPT topologies with multiple load-independent constant-current (CC) or constant-voltage (CV) outputs.
Abstract: The ability to concurrently power multiple loads has been a new feature for the inductive power transfer (IPT) system in more applications, such as the gate driver powering in the modular multilevel converter. As one of the applicable configurations, the domino-type IPT system cannot only transfer power over a longer distance but also achieves load-independent outputs. This article reviews the existing multiple-load IPT systems and aims to provide a methodology to systematically construct suitable domino-type IPT topologies with multiple load-independent constant-current (CC) or constant-voltage (CV) outputs. There are three innovative contributions. First, three kinds of resonant circuits are summarized to achieve the compensation network, including the series–series, T-type, and Π-type topologies. Second, nine CC and nine CV topologies are proposed, analyzed, and evaluated as candidates for various applications. The optimal CC and CV topologies are identified, and the integrated magnetic coupler designs are provided accordingly. Third, the power transfer capability is investigated, considering the parasitic resistances of passive components. The attenuation of load currents/voltages and the system efficiency relationship with load resistance, coupling coefficient k , quality factor Q , and load number N are analyzed, providing the guideline to design the load-independent domino system with high system efficiency. A single-input-four-output domino-type IPT system is implemented to validate the effectiveness of the proposed design methodology. Experimental results have shown consistency with the analysis results, and the efficiency can reach 89.79% when k = 0.193, Q = 320, and N = 4.
TL;DR: A new closed-form quasi-static model of the PCB resonators is derived and a fully automated simulation-driven optimization framework is constructed to enhance the quality factor of the resonator.
Abstract: The expanding functions of the emerging smart grid have posed new technical challenges on the power supplies for online monitoring systems in the transmission and distribution networks. A recent study has suggested that magnetic energy around the transmission line can be harvested and delivered wirelessly to the monitoring equipment through printed circuit board (PCB) resonators embedded inside an insulation rod. This article presents a rigorous analysis, modeling, and optimization of such PCB resonators. A new closed-form quasi-static model of the PCB resonators is derived. A fully automated simulation-driven optimization framework is constructed to enhance the quality factor of the resonator. Practical measurements show that the optimal design improves the quality factor ( $Q$ factor) from 52 to 132 as compared to the existing trial-and-error design. The corresponding wireless power transfer efficiency in a 20-W prototype across a 1.14-m distance improves significantly from 11 to 46%.
TL;DR: In this paper , a new IPT system with dual transmitters and dual receivers with integrated decoupling coils is introduced, where the proposed decoupled coils are also taking part in power transmission.
Abstract: To ensure the effectiveness of the inductive power transfer (IPT) systems for high-power applications, multiple coils are being used. However, cross couplings among the same-side coils reduce the efficiency of the system. Thus, decoupling coils are commonly used to mitigate the same-side couplings in a multiple-transmitter and multiple-receiver system. The decoupling coils are either used outside of the main coils or concentric with the main coils. In both cases, these decoupling coils do not take part in the power transmission and have some adverse effects on the system performance. In this article, a new IPT system with dual transmitters and dual receivers with integrated decoupling coils is introduced. Besides mitigating the mutual inductances of the same-side coils, the proposed decoupling coils are also taking part in power transmission. In addition, the proposed coils also have good misalignment performance. A 3-D finite-element analysis tool ANSYS MAXWELL is used to investigate the proposed magnetic coupler. A scaled-down experimental setup is used to verify the feasibility of the proposed structure. The maximum dc–dc efficiency of this system is 93.14% while delivering 700 W to the load with a 200-mm air gap. Besides, zero-voltage switching is also achieved in the experiment, which suggests that the proposed system can be an effective solution for the current drawbacks of the multiple-transmitter and multiple-receiver system.
TL;DR: Faraday coil transfer-power measurement (FC-TPM) employs non-contact, open-circuited sense coils to measure the electromagnetic field from WPT and calculates the real power propagating through the air gap between the transmitter and receiver coils.
Abstract: Wireless power transfer (WPT) is emerging as the preeminent way to charge electric vehicles, but there appears to be no fair way to measure the power transfer. In this article, Faraday coil transfer-power measurement (FC-TPM) is presented. FC-TPM employs non-contact, open-circuited sense coils to measure the electromagnetic field from WPT and calculates the real power propagating through the air gap between the transmitter and receiver coils. What is measured is the real electromagnetic power, representing the pure dispensation of energy that unambiguously demarcates the losses on either side. FC-TPM was demonstrated to be 0.1% accurate in hardware over an Rx coil misalignment of up to 10 cm using a 1-kW WPT system. Fair metering incentivizes businesses and individuals to make choices that conserve energy and advance technology by providing more information and by properly assigning the financial loss. This article is accompanied by a video highlighting the essential contributions of this article.
TL;DR: In this article , a comprehensive review has been performed on the history of the evolution, working principles and phenomena, design considerations, control methods and health issues of IPT systems, especially those based on EV charging.
Abstract: Nowadays, Wireless Power Transfer (WPT) technology is receiving more attention in the automotive sector, introducing a safe, flexible and promising alternative to the standard battery chargers. Considering these advantages, charging electric vehicle (EV) batteries using the WPT method can be an important alternative to plug-in charging systems. This paper focuses on the Inductive Power Transfer (IPT) method, which is based on the magnetic coupling of coils exchanging power from a stationary primary unit to a secondary system onboard the EV. A comprehensive review has been performed on the history of the evolution, working principles and phenomena, design considerations, control methods and health issues of IPT systems, especially those based on EV charging. In particular, the coil design, operating frequency selection, efficiency values and the preferred compensation topologies in the literature have been discussed. The published guidelines and reports that have studied the effects of WPT systems on human health are also given. In addition, suggested methods in the literature for protection from exposure are discussed. The control section gives the common charging control techniques and focuses on the constant current-constant voltage (CC-CV) approach, which is usually used for EV battery chargers.
TL;DR: In this article , the authors present existing issues and challenges related to the state-of-the-art solutions used for harvesting energy to power implantable devices and provide a brief overview of various power architectures found in the literature.
Abstract: For implantable medical devices, it is of paramount importance to ensure uninterrupted energy supply to different circuits and subcircuits. Instead of relying on battery stored energy, harvesting energy from the human body and any external environmental sources surrounding the human body ensures prolonged life of the implantable devices and comfort of the patients. In this article, we present existing issues and challenges related to the state-of-the-art solutions used for harvesting energy to power implantable devices. In addition, the details on existing energy storage technologies and various wireless power transfer techniques incorporating external or internal energy sources and sensors have been discussed. The authors have outlined the performance and power constraints of existing biomedical devices and provided a brief overview of various power architectures found in the literature. This survey has been conducted on existing implantable solutions in terms of output voltage, current, device dimension, application, generated power, energy density, and so on. Finally, the advantages and drawbacks of different solutions have been discussed and compared. Therefore, this article can be considered as an expedient reference for researchers conducting research in the field of energy scavenging, internal energy storage, wireless power transfer techniques, and power management of implantable medical devices.
TL;DR: In this article , the authors proposed an EV charging station recommendation algorithm to balance the regional load profiles of the power grid and the electric vehicle charging activity in order to transfer energy between the unbalanced distribution grids.
Abstract: Energy demand and supply vary from area to area, where an unbalanced load may occur and endanger the system security constraints and cause significant differences in the locational marginal price (LMP) in the power system. With the increasing proportion of local renewable energy (RE) sources in microgrids that are connected to the power grid and the growing number of electric vehicle (EV) charging loads, the imbalance will be further magnified. In this article, we first model the EV charging network as a cyber–physical system (CPS) that is coupled with both the transportation networks and the smart grids. Then, we propose an EV charging station recommendation algorithm. With a proper charging scheduling algorithm deployed, the synergy between the transportation network and the smart grid can be created. The EV charging activity will no longer be a burden for power grids, but a load-balancing tool that can transfer energy between the unbalanced distribution grids. The proposed system model is validated via simulations. The results show that the proposed algorithms can optimize the EV charging behaviors, reduce charging costs, and effectively balance the regional load profiles of the grids.
TL;DR: In this article , a cubic-magnetic coupler (CMC) was proposed for long-distance wireless power transfer, which has great capability of misalignment tolerance, and the distance-to-diameter ratio was defined to eliminate the impact of coil size and make the comparison between different couplers fairer and easier.
Abstract: This article proposes a kind of cubic-magnetic coupler (CMC) for inductive power transfer (IPT) system, which has huge application potential in the charging field of moving targets. The CMC can still maintain sufficient coupling coefficient when used for long-distance wireless power transfer, it also has great capability of misalignment tolerance. Distance-to-diameter ratio (DDR) is defined to eliminate the impact of coil size and make the comparison between different couplers fairer and easier. This article optimizes the parameters and shape of the CMC. Then, the proposed coupler is compared with several existing couplers employed in long-distance IPT systems. Double-sided LCC compensation topology is chosen to limit the current flowing through the coupling coils. A CMC with an outer size of 180×180×180 mm 3 was made, based on which an IPT prototype was built. The superiorities of the proposed coupler were verified by a series of experiments. When the DDR equals 3, the coupling coefficient of the CMC is 0.00985, and the maximum dc–dc and ac–ac efficiencies are 64.9% and 72.8%, respectively.
TL;DR: In this paper , a parameter optimization method is proposed for the electrical field resonance-based six-plate coupler system, where the ratio of the reactive power in the compensation network to the system transferred power is set as the main optimization goal.
Abstract: Wireless power transfer (WPT) is more convenient and safer than conductive charging for power consumer electronics, biomedical devices, transportation systems, etc. Inductive power transfer is the most widely studied and commercialized WPT technique; however, capacitive power transfer (CPT) is becoming an attractive alternative, offering better misalignment tolerance and lower cost and weight. The electrical-field-resonance-based six-plate coupler system is one of the most typical configurations for high-performance CPT systems, but the associated large number of circuit parameters is always a critical issue for system design. In this article, a parameter optimization method is proposed for this topology. The ratio of the reactive power in the compensation network to the system transferred power is set as the main optimization goal. To solve the high-order optimization problem, a two-stage method is proposed to significantly reduce the optimization complexity while providing the optimized parameters of the whole system. To verify the effectiveness of this method, a 3-kW, 1-MHz CPT system with a 16-pF coupling capacitor is built. Both the simulation and experimental results show that the optimized parameters effectively improve the system efficiency, experimentally achieving 95.7% dc–dc overall efficiency under a 100-mm gap distance at the rated power.
TL;DR: In this article , an improved hybrid parallel compensator (IHPC) was proposed for enhancing the power transfer capability of a photovoltaic (PV) grid-connected inverter.
Abstract: This article proposes an improved hybrid parallel compensator (IHPC) for enhancing the power transfer capability of a photovoltaic (PV) grid-connected inverter. A thyristor switched capacitor (TSC) module is used in series with a conventional inductive-coupling voltage source inverter to reduce the dc-link voltage. Under a low dc-link voltage, the voltage across the insulated gate bipolar transistor (IGBT) will also be low, which will reduce the voltage stress of the IGBT, thereby improving the reliability and reducing the loss of the voltage resource inverter. First, the mechanism of reactive compensation for improving the PV inverter power transmission capability is analyzed. Then, the circuit configuration and operating principle of the IHPC are introduced. After that, an optimal control strategy for the IHPC is proposed to address the resonance problem caused by the TSC connected in series with the L filter and to improve the compensation performance of the IHPC. Finally, the effectiveness of the proposed IHPC and the control method is validated by the simulation and experiments. The results show that the IHPC with optimal control strategy can achieve continuous reactive power compensation under a low dc-link voltage, thereby enhance PV power transfer capability.
TL;DR: In this paper, a three-stage five-coil inductive power transfer (IPT) system which is based on cylindrical solenoid coupler (CSC) is proposed.
Abstract: A three-stage-five-coil inductive power transfer (IPT) system which is based on cylindrical solenoid coupler (CSC) is proposed in this article. The shape and parameters of the CSC are optimized. The five litz coils compensated by series capacitors are considered to form an IPT system based on equivalent CLC/S/CLC compensation topology with constant voltage characteristics. The mutual inductance between compensation auxiliary coil (CAC) and power transfer coil could be changed by moving the position of CAC, and the freedom of parameter design is enhanced. Mathematical model and loss model of the system are established, and power transfer characteristics of the system are analyzed. The system is considered to be used as a power source for state detection equipment of high-voltage (HV) device to achieve long-distance IPT, the effect of the coupler on the HV electric field is verified. Finally, a prototype with a length of 1.54 m was built. Based on the platform, output voltage and dc–dc power transfer efficiency curves with changed input voltage and load are obtained. The maximum efficiency of the dc–dc system can reach about 60%.
TL;DR: In this article , a new accurate method is presented for foreign object detection based on an electromagnetic model for wireless power transfer (WPT) systems, which can detect a 2 cm diameter U.S. nickel coin, a small disposable lighter, and a saline proxy for a living animal in a kilowatt-level WPT system, using a prestartup power of only 7 W.
Abstract: Foreign objects near wireless power transfer (WPT) systems are fire hazards that must be detected. In this article, a new accurate method is presented for foreign object detection based on an electromagnetic model for WPT. Foreign objects are detected by quantifying the deviation from a normal model. This deviation is caused by the foreign object's additional electromagnetic coupling. Advantages of this new method include invariance to receiver coil misalignment, and power level, allowing low-power detection prior to startup. Electromagnetic model-based foreign object detection was demonstrated in hardware to detect a 2 cm diameter U.S. nickel coin, a small disposable lighter, and a saline proxy for a living animal in a kilowatt-level wireless power transfer system, using a prestartup power of only 7 W. Furthermore, foreign objects can be detected regardless of an Rx coil misalignment of up to 10 cm. This article is accompanied by an instructional video.