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This study focuses on using wireless power transfer (WPT) technology based on magnetic resonant coupling (MRC) to supply electric power to an endoscopic capsule to be used for the direct feeding of specific functions or for battery charging. One of the main limitations of the diffusion of endoscopic capsules is the limited autonomy of the internal battery. The aim of the paper is to present an innovative system to wirelessly power capsules using inductive coupling. Here, a new transmitting coil architecture is proposed to allow the wireless charging of the capsule equipped with a monoaxial receiving coil for any possible geometric position and orientation. The new wearable transmitting coil consists of four rectangular coils with independent excitations, and it is capable of producing a magnetic field in any direction. The obtained results in terms of electrical performance of the proposed WPT system and in terms of in situ electromagnetic physical quantities are compared with the basic restrictions of electromagnetic field (EMF) safety guidelines. The results obtained are very promising, as the proposed WPT configuration can transfer at least 250 mW in a capsule that travels along the entire gastrointestinal tract.

This study deals with the development of a new power supply system implanted in the human body to feed several implantable medical devices (IMDs). The power system is energized from outside the human body via a transcutaneous wireless power transfer (WPT) link implanted in a subcutaneous pocket. The internal power system is equipped with a backup battery and can continuously power multiple IMDs for a maximum power of 25 W. As a demonstration of the proposed solution, different IMDs are considered. An experimental setup was carried out and laboratory tests were performed on real devices to demonstrate the feasibility and efficiency of the proposed solution.

This article deals with the design of a wireless powering system for a left ventricular assist device (LVAD). The modern LVAD is mainly a miniaturized blood pump attached to the heart and is driven by an electric motor powered by a cable driveline that exits the patient's body through the skin to be connected with an external battery. The driveline is a portal to the exterior environment and this can cause frequent and severe infections. The goal of this article is the elimination of the cable link between the interior and the exterior of the human body. To this aim, an innovative powering design of the LVAD is proposed adopting the wireless power transfer (WPT) technology based on magnetic resonant coupling. The main challenges in the design of a WPT system for LVAD application are the considerable implantation depth (5-10 cm) and the relatively high power (≈5 W) required by the device to operate continuously. Two different design solutions are proposed: 1) a subcutaneous receiving coil connected to the LVAD by a short driveline completely inside the human body and 2) an LVAD with a receiving circuit and coil, both integrated on it.

This paper presents an automatic scanning solution for measuring nonuniform magnetic fields captured by a tri-axial sensor connected to a time-domain acquisition system over a robotic arm. The sensor has been realized and calibrated through a canonical configuration consisting of Helmholtz coils. The acquisition system is instead executed by a Red Pitaya, which is an FPGA-based board with high performance and reliability regarding the sampling rate of the input signal. A LabVIEW software has then been developed for the acquisition of the sampled signal over time, the calculation and post-processing of the magnetic field, and the data saving. Finally, an Arduino-based robotic arm has been employed to make the acquisition system fully automated. This is particularly useful for the compliance assessment against electromagnetic field exposures at workplaces.

Dynamic wireless power transfer (DWPT) of electric vehicles (EVs) is the future of urban mobility. The DWPT is often based on a series of short track pads embedded in road pavement that wirelessly transfers electrical energy to EVs equipped with a pickup coil for battery charging. An open problem with this technology is the variation of the coupling factor as a vehicle switches from one transmitting coil to another during its motion. This can cause a significant change in power with possible power spikes and holes. In order to overcome these issues, a new architecture is here proposed based on two pick-up coils mounted in the vehicle underneath. These identical receiver coils are placed in different positions under the vehicle (one in front and the other in the rear) and are activated one at a time so that inductive coupling is always good enough. This innovative configuration has two main advantages: (i) it maintains a nearly constant coupling factor, as well as efficiency and transferred power, as the vehicle moves along the electrified road; (ii) it significantly reduces the cost of road infrastructure. An application is presented to verify the proposed two-coil architecture in comparison with the traditional one-coil. The results of the investigation show the significant improvement achieved in terms of maximum power variation which is nearly stable with the proposed two-coil architecture (only 2.8% variation) while there are many power holes with the traditional single coil architecture. In addition, the number of the required transmitting coils is significantly reduced due to a larger separation between adjacent coils.

The paper deals with the application of the wireless power transfer (WPT) technology, based on near field inductive coupling, in implantable medical devices (IMDs). A transcutaneous WPT system is considered here to transfer a power of over 10 watts. The selection of the most adequate topology of the compensation network is a key point to mitigate the variation of physical quantities inside the human body, such as internal electric field E and specific absorption rate (SAR). An investigation is here provided to demonstrate the different behavior of each compensation topology in order to obtain compliance with ICNIRP limits in biological tissues.

This study deals with a preliminary analysis of the electromagnetic interference (EMI) produced by a dynamic wireless power transfer (DWPT) system on an underground traffic signal cable. The considered DWPT is composed by an electrified lane with short-track pads architecture. The induced effects in a multiconductor underground cable are calculated by the theory of field-excited multiconductor transmission line (MTL) where the distributed sources are derived from the electromagnetic field generated by the DWPT coils operating at 85 kHz and transferring a power of 10 kW. The obtained preliminary results, validated by comparison with other methods, show that the induced current on a traffic signal cable is small for higher odd harmonics, while it is negligible for even harmonics. Thus, only the first harmonic could produce EMI.

This study deals with the design of a near-field wireless power transfer (WPT) system applied to a left ventricular assist device (LVAD) to treat patients with heart-failure problems. An LVAD is an implanted electrically driven pump connected to the heart and is traditionally powered by batteries external to the human body via a percutaneous driveline cable. The main challenge of wirelessly powering an LVAD implanted deep in the human body is to transfer relatively high power with high efficiency levels. Here the optimal design of the primary and secondary WPT coils is proposed to improve the performance of the WPT, avoiding possible safety problems of electromagnetic fields (EMF). As a main result, an average power of 5 W is continuously delivered to the LVAD by the WPT system working at 6.78 MHz with a total (DC–to–DC) efficiency of approximately 65% for the worst-case configuration.

An uninterruptable wireless power supply is developed for a left ventricular assist device (LVAD), which is an implanted, electrically driven centrifugal pump used to treat advanced heart failure pathologies. The LVADs are currently powered through a cable driveline (DL) that exits the patient's body through the skin. Here, an innovative uninterruptable power supply is presented, based on a hybrid wireless/wired architecture: the electric power of 10 W is transferred by the near field wireless power transfer technology operating at 300 kHz, from outside the human body to an implanted subcutaneous receiver, and then by an internal cable to the LVAD. A significant improvement of the subcutaneous receiver is here proposed, based on the integration in the receiving coil of a battery pack providing the following benefits: no-break power supply for the LVAD; peak load management; enhanced system reliability; elimination of DL infection; enhancement of patient's quality of life. The proposed system is first designed and optimized, then a demonstrator is made and tested in a laboratory using the latest LVAD generation. The measured coil currents are used as sources for dosimetric analysis to assess the compliance of the system with the electromagnetic field safety and thermal regulations.

This article deals with an innovative wireless charging system for an implanted capsule robot. The transmitting coil is given by a combination of a Helmholtz coil and a birdcage coil. This coil configuration generates a magnetic field with all nonzero field components for any location within the human torso. Therefore, a single axis receiving coil wound around a cylindrical shaped ferrite core is able to receive a significant quantity of electrical energy for any capsule orientation and position. Design guidelines are provided and illustrative examples are given. Assuming a capsule of 2 cm length and 1 cm diameter we can transfer at least 1 W to the load with a minimum power transfer efficiency larger than 10% without considering electronic losses. Finally, compliance with electromagnetic field safety limits is assessed by a numerical dosimetric analysis.

This study focuses on the development of a new power supply architecture for an implanted cardiac defibrillator (ICD) and a left ventricular assist device (LVAD). In the proposed solution a transcutaneous wireless power transfer technology (WPT) based on magnetic resonance coupling is adopted assuming an on-body transmitting coil and a subcutaneous receiving coil. With this solution, the percutaneous driveline of the LVAD is eliminated, reducing the risk of infection. The WPT receiver is integrated with the ICD. The proposed power supply using a rechargeable ICD battery allows the LVAD to be continuously powered and the ICD battery to be recharged periodically.

This article deals with the electromagnetic interference (EMI) in a cardiac implantable electronic device (e.g., implantable cardioverter-defibrillator or cardiac resynchronization therapy) generated by a left ventricular assisted device (LVAD) powered by a wireless power transfer (WPT) system. Wireless LVAD, not yet available in the market, is currently being investigated for many aspects spanning from electronics, hydraulic, electrical feeding, mechanical, and its possible impact on other implanted devices, such as a cardiac implantable electronic device (CIED). No results are yet published on possible EMI effects produced by the WPT coil currents in the pacing leads of a CIED implanted in the same patient with the LVAD. To this aim, the next generation of wireless LVADs with transcutaneous WPT system is first described, and, then, used to predict the induced voltage by the WPT system on a CIED lead. The obtained results demonstrate as the proposed WPT system, tested in accordance with the ISO 14117 standard, does not interfere with other CIEDs.

This study deals with the analysis of an optimum configuration for a wireless powering system applied to a left ventricular assisted device (LVAD). The current models of LVAD are miniaturized pump that are attached directly to heart by mini-invasive technique and can be used to treat advanced heart pathologies. The pump is electrically driven by a DC brushless motor powered by an external battery connected to the motor by percutaneous driveline cable. This last is cause of many infections and should be eliminated. Aim of this work is the study of a wireless power transfer (WPT) system used to power the motor replacing the percutaneous driveline. Electrical performances, safety aspects and reliability of the system are all aspects of paramount importance. A backup battery integrated with the implanted secondary coil is also proposed. This solution permits to improve the system reliability with a minimum number of components that must be subcutaneously implanted.

This study deals with the optimization of a shielding structure composed by multiple active coils for mitigating the magnetic field in an automotive wireless power transfer (WPT) system at 85 kHz. Each active coil is independently powered and the most suitable excitation is obtained by an optimization procedure based on the Gradient Descent algorithm. The proposed procedure is described and applied to shield the magnetic field beside an electric vehicle (EV) equipped with SAE standard coils, during wireless charging. The obtained results show that the magnetic field in the most critical area is significantly reduced (i.e., approximately halved) with a very limited influence on the electrical performances (i.e., WPT efficiency decreases by less than 1 percentage point compared to the case without active shielding).

The shielding technique by active coils is proposed to mitigate the magnetic field produced by a dynamic wireless power transfer (WPT) system for wireless recharging the batteries of in motion electrical vehicles (EVs). Active planar coils mounted in an electrified road with multiple-pads architecture are proposed. The active coils are adequately powered so that the field in surrounding of the electrified road is compliant with reference levels (RLs) of ICNIRP 2010 guideline. The influence of the active shielding system on the performance of the WPT system is also investigated.

A novel design of active coil shielding is proposed to reduce the magnetic field generated by the currents flowing into the coils of a wireless power transfer (WPT) system for charging the batteries of an electric vehicle (EV). The main idea is to divide the traditional active loop used to shield a source in two separate shielding coils so as not to adversely affect the WPT performance. This concept is applied to shield the WPT coils, and, therefore, in the proposed design, there are active coils placed on the ground parallel to the primary coil of the WPT and some others on board below the vehicle, planarly located with the secondary coil. The currents on the active coils are optimized in order to minimize the magnetic field in the most critical zone accessible from humans, i.e., region besides the EV and in the cabin.

The artificial material single-layer (AMSL) method, recently proposed to model solid conductive shields in finite-element solvers without using a fine discretization, is here extended to model multilayer shields. First, the admittance matrix of a multilayer shield is analytically derived by the transmission line (TL) theory. Then, considering that the field through conductive shields propagates normally to the shield surface, the TL admittance matrix is equated to that of a 1-D finite element to extract the physical constants of a homogenized artificial material. These constants are adopted to model the multilayer shield region in the finite-element method (FEM) calculations by using only one layer of finite elements in the direction of the field propagation. By the AMSL-FEM, the field propagation through the multilayer shield is accurately modeled taking into account the skin effect and avoiding the fine discretization of the shield.

This paper deals with the extension of the artificial material single-layer (AMSL) method, recently developed to model electromagnetically a thin conductive material using the finite-element method (FEM), to the more general case of transversally anisotropic shields. The analogy between the field equations and the multiconductor transmission line (MTL) equations is here used to calculate the admittance matrix of a thin anisotropic material. This admittance matrix is then imposed to be that of an equivalent circuit with lumped parameters. Thus, it is possible to synthetize the AMSL tensors containing the specific constants to be used in commercial software tools. The adoption of the AMSL method in FEM simulations avoids a fine discretization inside the thin conductive anisotropic material required at high frequency. Simple tests are finally carried out to validate the proposed method.

This paper deals with the numerical evaluation of the magnetic field emitted by a wireless power system (WPT) in an electric vehicle (EV). The numerical investigation is carried out using a finite element method (FEM) code with a transition boundary condition (TBC) to model conductive materials. First, the TBC has been validated by comparison with the exact solution in simple computational domains with conductive panels at frequencies used in WPT automotive. Then, the FEM with TBC has been used to predict the field in an electric car assuming the chassis made by three different materials: steel, aluminum, and fiber composite. The magnetic field source is given by a WPT system with 7.7 kW power level operating at frequencies of 85 or 150 kHz. The calculated magnetic field has been compared with the International Commission on Non-Ionizing Radiation Protection (ICNIRP) reference level demonstrating compliance for an EV with metallic (steel or aluminum) chassis. On the contrary, a fiber composite chassis is much more penetrable by magnetic fields and the reference level is exceeded.

This paper deals with the intrasystem electromagnetic interference (EMI) in a pacemaker equipped with a wireless power transfer (WPT) charging system. The WPT application to pacemakers is very new, and no results are yet published on possible EMI effects produced by the WPT coil currents in the pacemaker pacing leads. To this aim, an efficient and original co-simulation circuit/field method is proposed to predict the induced voltages on a pacing lead. In the numerical calculation, the pacemaker with WPT secondary coil and a pacing lead is implanted in a sophisticated human body model. The numerical results are validated by measurements showing a good agreement. The proposed approach would be a useful tool for pacemaker EMI compliance tests and safety assessment evaluations.

This study deals with the inductive-based wireless power transfer (WPT) technology applied to power a deep implant with no fixed position. The usage of a large primary coil is here proposed in order to obtain a nearly uniform magnetic field inside the human body at intermediate frequencies (IFs). A simple configuration of the primary coil, derived by the Helmholtz theory, is proposed. Then, a detailed analysis is carried out to assess the compliance with electromagnetic field (EMF) safety standards. General guidelines on the design of primary and secondary coils are provided for powering or charging a deep implant of cylindrical shape with or without metal housing. Finally, three different WPT coil demonstrators have been fabricated and tested. The obtained results have demonstrated the validity of the proposed technology.

A novel design of active coils is proposed to reduce the magnetic field generated by the currents flowing into the coils of a wireless power transfer (WPT) system for recharging the batteries of an electric vehicle (EV). The main idea is to split the traditional active loop, in two separate shielding coils. They have semi-annular shape and are placed on the ground pad around the WPT primary coil. The geometry and excitation of the active coils are varied to minimize the magnetic field beside the active coils without degrading the WPT electrical performance.

A near-field wireless power transfer (WPT) technology is applied to recharge the battery of a small size drone. The WPT technology is an extremely attractive solution to build an autonomous base station where the drone can land to wirelessly charge the battery without any human intervention. The innovative WPT design is based on the use of a mechanical part of the drone, i.e., landing gear, as a portion of the electrical circuit, i.e., onboard secondary coil. To this aim, the landing gear is made with an adequately shaped aluminum pipe that, after suitable modifications, performs both structural and electrical functions. The proposed innovative solution has a very small impact on the drone aerodynamics and the additional weight onboard the drone is very limited. Once the design of the secondary coil has been defined, the configuration of the WPT primary coil mounted in a ground base station is optimized to get a good electrical performance, i.e., high values of transferred power and efficiency. The WPT design guidelines of primary and secondary coils are given. Finally, a demonstrator of the WPT system for a lightweight drone is designed, built, and tested.

This study deals with the design of a wireless powering system for a left ventricular assist device (LVAD). The proposed system uses the wireless power transfer (WPT) technology based on the magnetic resonant coupling. For this kind of application two main aspects must be taken into account. First, the LVAD is implanted in the heart, so the power must be wirelessly transferred at a significant depth inside the human body. Second, the LVAD requires a much higher power than other active implantable medical devices (AIMDs) and for 24 hours per day, 365 days a year. To this aim an adequate design of the electrogeometrical configuration of the WPT coils is proposed. A feasibility study is therefore carried out to define possible solutions for WPT application to an LVAD.

The shielding technique by active coils is proposed to mitigate the magnetic field produced by a wireless power transfer (WPT) system based on near field coupling. General guidelines are provided for the active shielding design to shield the source for emission reduction or to shield the victim for immunity enhancement. Then, a method is proposed to identify the suitable excitation of the active coils. The proposed method permits the mitigation of the magnetic field in a specific point or of the induced effects in a loop area. Furthermore, the influence of the active shielding on the performance of a WPT system is also investigated. Finally, the proposed solution for active shielding is validated by measurements. A shielding effectiveness (SE) of about 20 dB on the considered area is obtained with a negligible degradation of the WPT system efficiency.

An innovative shielding configuration of active coils is proposed to mitigate the magnetic field around an electric vehicle (EV) with a wireless power transfer (WPT) system during battery charging. The active coil is designed to reduce the risk for patients with pacemakers or similar devices produced by the time varying magnetic field generated by the 85 kHz WPT coil currents. A numerical analysis of the magnetic field levels is carried out solving the magneto-quasi-static (MQS) equations by a FEM-based commercial tool. The calculated field which exceeds the limits of electromagnetic compatibility (EMC) and electromagnetic field (EMF) safety standards for human exposure is mitigated by active coils. The magnetic field levels in the environment and the induced peak-to-peak voltage in the pacing lead is predicted in presence and in absence of active shielding.

Numerical dosimetry makes it possible to evaluate the influence of electromagnetic fields on the human body. The interest of performing numerical dosimetry starting from data coming from general purpose software or measurements is constantly growing. This paper compares two available methods that make dosimetry starting from the knowledge of the magnetic flux density. The quality of results is analyzed considering both exact and uncertain inputs stressing out when one method should be preferred over the other. Finally, the methods are validated using real measurements obtaining good results.

An innovative coil configuration for inductively-based wireless power transfer (WPT) technology is presented to recharge the battery of a compact unmanned aerial vehicle (UAV) (i.e., a remotely controlled drone). To improve the tolerance of the WPT system to coil misalignment caused by imperfect landing, a large primary coil is proposed in combination with a single turn, secondary coil. The on-board secondary coil is integrated in a part of the drone used as protection of the propellers. The single turn configuration of the secondary coil is efficient from an electrical point of view and very convenient as the additional weight installed on-board the drone is very limited.

The paper provides a parametric investigation on the magnetic field produced by a wireless power transfer (WPT) system to recharge the battery of an electric vehicle (EV), varying the position of the secondary coil in the car underbody. The considered WPT charging system operates at the frequency of 85 kHz with a power of 7.7 kW. The WPT system creates a very strong magnetic field that can be critical for human exposure to electromagnetic fields (EMF) and for immunity of implanted medical devices. The presence of the conductive body-frame of the vehicle permits to shield the magnetic field inside the cabin, but beside the vehicle the field level is significant. Several factors (installation position of the secondary coil; coil alignment; vehicle shape and dimensions; ground clearance; body material; etc.) that influence the magnetic field behavior are considered. Different EV-WPT coil configurations are examined and the magnetic field levels are predicted by numerical simulations. From the obtained results general guidelines for the optimal position of the WPT system are provided.