Frequency Power Transfer Research Articles

Power transfer efficiency in an air-breathing radio frequency ion thruster

Abstract Due to a series of challenges such as low-orbit maintenance of satellites, the air-breathing electric propulsion has got widespread attention. Commonly, the radio frequency ion thruster is favored by low-orbit missions due to its high specific impulse and efficiency. In this paper, the power transfer efficiency of the radio frequency ion thruster with different gas composition is studied experimentally, which is obtained by measuring the radio frequency power and current of the antenna coil with and without discharge operation. The results show that increasing the turns of antenna coils can effectively improve the radio frequency power transfer efficiency, which is due to the improvement of Q factor. In pure N2 discharge, with the increase of radio frequency power, the radio frequency power transfer efficiency first rises rapidly and then exhibits a less steep increasing trend. The radio frequency power transfer efficiency increases with the increase of gas pressure at relatively high power, while declines rapidly at relatively low power. In N2/O2 discharge, increasing the N2 content at high power can improve the radio frequency power transfer efficiency, but the opposite was observed at low power. In order to give a better understanding of these trends, an analytic solution in limit cases is utilized, and a Langmuir probe was employed to measure the electron density. It is found that the evolution of radio frequency power transfer efficiency can be well explained by the variation of plasma resistance, which is related to the electron density and the effective electron collision frequency.

Rechargeable Active Implantable Medical Devices (AIMDs)

Active Implantable Medical Devices (AIMDs) act as lifesaving devices. They provide electrical signals to tissues as well as perform data-logging operations. To perform these operations, they need power. The battery is the only source for such devices, as they are placed invasively inside the human body. Once the battery drains out, the patient wearing the device has to undergo medical surgery for the second time, where there are many chances of infections, and it could be life-threatening too. If the AIMDs, e.g., pacemakers are designed using rechargeable batteries, then the devices can be recharged regularly, which can increase the life of the device as well as reduce its size. Wireless charging of AIMDs such as ICDs or pacemakers is proposed in this paper using magnetic resonant coupling. The selection of frequency for power transfer is the most crucial part, as the basic restriction (BR) criteria proposed by ICNIRP guidelines and the IEEEC95.1 standard need to be followed, which ensures the safety of the patient. This is suggested by considering some basic restriction parameters, such as specific absorption rate (SAR) and current density, as suggested by guidelines. In this paper, experimentation using two frequencies is shown, i.e., 1.47 MHz (the high frequency) and 62 KHz (the low frequency). For experimentation, goat flesh and saline solution are used. Secondary coil and flesh are dipped in the saline solution. Battery recharging performed at a lower frequency took less time than with a frequency in the MHz range. All BR criteria are fulfilled for both frequencies, so the proposed methodology is safe to use.

Capacitive Power Transfer System With Integrated Wide Bandwidth Communication

This letter proposed a novel method for compensation network design used in capacitive power transfer (CPT) systems to achieve simultaneous power and data delivery. The proposed method combines both ladder filter and resonant circuit designs, allowing the existing double-sided CL compensation topology to exhibit different characteristics under the power channel and the communication channel. The proposed system significantly reduces the design complexity and increases the bandwidth for data transfer while maintaining the circuit resonance at the wireless power transfer frequency. The system is compatible with both amplitude shift keying (ASK) and frequency shift keying (FSK) modulation methods, passing the high-frequency data carrier with an approximately unity gain. Detailed circuit parameter design and system performance analysis are presented, and a new metric power to signal is introduced to analyze the effect of the data communication on the power transfer. A prototype CPT system rated at 10 W is built, which demonstrates a 81.2% dc–ac efficiency and a data transfer rate of 10 kbps by using either ASK or FSK modulation techniques.

Undersea Wireless Power and Data Transfer System With Shared Channel Powered by Marine Renewable Energy System

Marine renewable energy (i.e., wave, tidal or ocean current, thermal gradient, and salinity gradient), can revolutionize ocean observing capabilities and marine power supply method. Under the marine environment, as the conductive feature of seawater, it has big challenge for wireless power and signal transfer under marine environment. To deal with this issue, this paper provides an undersea wireless power and data transfer system with the shared channel which powered by renewable system. The power and data could be transferred with the same channel based on the time division multiplexing theory. In one switching cycle, the power is transferred in the first half switching cycle and the data is transferred in the second half switching cycle. The data is modulated by frequency-shift keying (FSK) modulation method. The frequency for power transfer is set as 240 kHz. With the FSK modulation method, the two signal carriers’ frequencies are respectively set 10 MHz and 2 MHz. The data could be completely transferred with the high bandwidth. The glass tank experimental platform is constructed with the 35‰ salinity water. The simulated and experimental results verify the theory analysis and the calculation very well.

Beam Shaping for Wireless Optical Charging with Improved Efficiency

Optical wireless charging is a nonradiative long-distance power transfer method. It may potentially play an important role in certain scenarios where access is challenging, and the radio frequency power transfer is less efficient. The divergence of the optical beam over distances is a key limiting factor for the efficiency of any wireless optical charging system. In this work, we propose and experimentally demonstrate a holographic optical beam shaping system that can restrict the divergence of the optical beam. Our experimental results showed up to 354.88% improvement in the charging efficiency over a 10 m distance.

Systematic Design and Analysis of Wireless Power Transmission and Energy Distribution

The paper reports a systematic design and analysis of two independent public utilities-wireless power transmission and renewable energy distribution. Wireless Power transmission means the transmission of power from the power source to the load circuit wirelessly. It is a complex process but the demand for electricity is more than the amount being produced. The principle of the Project is based on Faraday’s Law of Electromagnetic induction. In this project, we run the High AC Frequency power transfer operation. The second design discusses renewable energy sources. Now a day's power is the most required office for the person. All the standard energy assets square measure draining step by step. Along these lines, we've to move from standard to non-traditional energy assets. During this, the blend of 2 energy assets is happening for example wind and elective energy. This technique castigates the property energy assets while not harming the character. We will give continuous force by exploiting the half-breed energy framework. Essentially this method involves the combination of 2 energy systems that may provide continuous power. Star panels square measure utilized for changing elective energy and wind turbines square measure utilized for changing breeze energy into power. This force will use for varied purposes. Age of power happens at a cheap price. This project manages the age of power by exploiting 2 sources blend that winds up in produce power at a cheap price while not harming the character balance.

Self-Powered Implantable Medical Devices: Photovoltaic Energy Harvesting Review.

Implantable technologies are becoming more widespread for biomedical applications that include physical identification, health diagnosis, monitoring, recording, and treatment of human physiological traits. However, energy harvesting and power generation beneath the human tissue are still a major challenge. In this regard, self-powered implantable devices that scavenge energy from the human body are attractive for long-term monitoring of human physiological traits. Thanks to advancements in material science and nanotechnology, energy harvesting techniques that rely on piezoelectricity, thermoelectricity, biofuel, and radio frequency power transfer are emerging. However, all these techniques suffer from limitations that include low power output, bulky size, or low efficiency. Photovoltaic (PV) energy conversion is one of the most promising candidates for implantable applications due to their higher-power conversion efficiencies and small footprint. Herein, the latest implantable energy harvesting technologies are surveyed. A comparison between the different state-of-the-art power harvesting methods is also provided. Finally, recommendations are provided regarding the feasibility of PV cells as an in vivo energy harvester, with an emphasis on skin penetration, fabrication, encapsulation, durability, biocompatibility, and power management.

A Simultaneous Wireless Information and Power Transfer System With Independent Channel for Information Transfer

Reliable communication between the primary and the secondary side is a challenge for simultaneous wireless information and power transfer (SWIPT) system. Considering many factors, such as cost, device size, and transmission efficiency, the SWIPT system transferring multiple frequencies with a single inductive link is an effective scheme to integrate reverse data communication. However, those SWIPT systems change power transfer frequency or power carrier amplitude while transferring information, then information cannot be transmitted when the inverter does not work, which reduces the reliability of communication. To solve this problem, this paper proposes an idea of establishing an independent information transfer channel, the power and information transmits at different frequencies. The information transmitted in the reverse direction no longer flows through the primary side inverter. It is guided to an independent channel after being transmitted to the primary side through the common inductive link. Its equivalent circuit model is provided to analyze the transfer gain, power transfer performance, and the relationship between the information coupling circuit and information transfer characteristics. Finally, a SWIPT prototype is built to validate the proposed SWIPT system.

High rectification sensitivity of radiofrequency signal through adiabatic stochastic resonance in nanoscale magnetic tunnel junctions

Rectification is an important stage in electronic circuits for any wireless radio frequency power transfer application. Currently, Schottky diodes are widely used as rectifiers; however, they are inefficient at low power levels of microwatts or less (providing maximum sensitivities around 4 mV/μW). Nanoscale magnetic tunnel junctions can serve as alternative rectifiers by utilizing the so-called spin-torque diode effect, demonstrating a much higher rectification sensitivity (200 mV/μW) compared to Schottky diodes. However, for this mechanism to work, the signal frequency must match the ferromagnetic resonance frequency, which typically lies in the gigahertz range. For signals in the megahertz range or lower, Schottky diodes remain the only option for rectification. Here, we demonstrate a mechanism based on thermally activated adiabatic stochastic resonance in magnetic tunnel junctions to produce low frequency (up to tens of megahertz) signal rectification at low input power (submicrowatt), with a sensitivity of up to 35 mV/μW—higher than state-of-the-art Schottky diode rectifiers at this frequency and power range. These findings suggest magnetic tunnel junctions as potential alternatives to Schottky diodes for low frequency and low power applications.

Wireless Power Transfer Through Inductive Coupling For Aimds

For the patients with some cardiovascular diseases, implantable devices like implantable cardiac pacemakers and implantable cardioverter defibrillators play a very important role. The life of implantable device is limited by the life of battery and the size of implanted device is dependent on size of battery. More life of battery demands larger battery size. Since these devices are implanted inside the human body, they must be small in size as well as of long battery life. Wireless re-charging of such devices can only be the solution to reduce the size and increase life of AIMDs. Wireless recharging by magnetic resonance coupling in less time is expected and hence this topic is considered for more research to have uninterrupted power supply from battery. Selection of operating frequency for transfer of power wirelessly is of great concern as it requires attention towards certain guidelines as basic restrictions provided by International Commission on non-ionizing Radiation Protection (ICNIRP). With lower frequencies used for power transfer, the efficiency would be less whereas with higher frequencies efficiency would be higher but with the use of higher frequencies for power transfer certain biological issues needs attention like tissue heating. In the technique of wireless power transfer, the transmitting coil is assumed to be outside the body and receiver coil is considered to be inside the human body above the pacemaker shell. The efficiency of power transfer is affected by frequency for power transfer and distance between the two coils.

A 50-V Isolation, 100-MHz, 50-mW Single-Chip Junction Isolated DC-DC Converter With Self-Tuned Maximum Power Transfer Frequency

A fully integrated, point-of-load, low-noise, isolated dc–dc converter for supply regulation of high dynamic range analog and mixed-signal isolated sensor signal-chains is presented. The isolated dc–dc converter utilizes an integrated planar air-core micro-transformer as a coupled-resonator and an isolation barrier, and enables direct connection of low-voltage mixed-signal circuits to higher supply rails for current and voltage sensing. The transformer is driven at its resonant frequency of 100 MHz to achieve maximum power transfer. A mixed-signal perturb-and-observe-based frequency search algorithm is developed to improve maximum power transfer efficiency by 60% across the isolation barrier compared to fixed driving frequency method. The switching ripple at output is reduced by 11 dB utilizing spread spectrum clocking in the driver, and 21 dB using a low-dropout regulator. Conducted and radiated EMI distribution on the IC is measured by a set of proposed ring oscillator-based noise sensors with −68-dBm noise sensitivity. The proposed isolated converter achieves the highest level of integration compared to state-of-the-art integrated isolated converters, and provides 50-V on-chip junction isolation using standard CMOS technology.

Investigation of the power transfer efficiency in a radio-frequency driven negative hydrogen ion source

The radio frequency power transfer efficiency is experimentally and numerically investigated in an inductively coupled negative hydrogen ion source. The discharge is operated in a low pressure range of 0.1–3 Pa at a driving frequency of 2 MHz and an applied power of up to 6 kW. In the experiment, the power transfer efficiency value is determined by measuring the applied power and current through the antenna coil both with and without discharge operation. Fundamental properties, such as electron density and effective electron temperature, are obtained by means of a Langmuir probe. The effect of the antenna coil turns, N, is also studied in a range of 5–9 turns. It is found that more coil turns can significantly enhance the power transfer efficiency due to the remarkably increasing quality factor of the system. Moreover, the experimental results show that the power transfer efficiency first increases and then reaches the maximum with increasing applied power, while it first increases quickly and then rises at a slower rate with increasing gas pressure. In order to give a comprehensive knowledge of the power absorption mechanism, a self-consistent hybrid model is developed. It is found that the numerical results are in reasonable agreement with that measured in the experiment. The numerical results and the analytic solutions in the limit cases of low and high pressures can well explain the various trends of the power transfer efficiency obtained in the experiment. These trends mainly depend on the quality factor Q, the electron density, and the effective electron collision frequency.

A Simultaneous Power and Downlink Data Transfer System With Pulse Phase Modulation

This brief presents a pulse phase modulation scheme for simultaneous wireless power and downlink data transfer system through the same inductive link. It is proved that the impact of data transfer on power transfer can be minimized when using the proposed pulse phase modulation. A prototype is built up with 1-MHz resonant frequency for power transfer. It shows that the data can be successfully transferred while achieving a data rate of 125 kb/s, which is 1/8 of carrier frequency, and a bit error rate (BER) of $4.5\boldsymbol {\times } 10^{\boldsymbol {-6}}$ . Furthermore, compared with the case without data transfer, the input powers and the output powers are almost unchanged, respectively.

Induced Current Calculation in Detailed 3-D Adult and Child Model for the Wireless Power Transfer Frequency Range

Induced current density in the human body is the basic restriction of the electromagnetic field protection guidelines for frequencies . Due to the difficulty of measurement, numerical methods are often used for assessment of basic restrictions. In this paper, induced current distributions are calculated in the high-resolution 3-D adult and child models exposed to magnetic fields between 100 kHz and 10 MHz, which is the frequency range of the resonant wireless power transfer (WPT) systems. For this frequency range, it is difficult to apply the conventional finite-difference time-domain (FDTD) method for bioelectric field computation. Thus, the quasi-static FDTD method is used to reduce the number of time steps. The results are analyzed according to different human models, grounding conditions, organs, frequencies, and orientations of the incident magnetic field. In addition, the plane wave exposure is compared with exposure to magnetic field of transmit coil of WPT system. Using the calculation results, the feasibility of the magnetic field reference level in the International Commission on Non-Ionizing Radiation Protection guideline is analyzed.

Feeding System of a High-Frequency Accelerating Cavities of the Novosibirsk Microtron-Recovery Unit for The Fel. Divider of a High CW Power on the Basis of a Rectangular Waveguide

The article is devoted to the system of the Radio Frequency power transfer and distribution between accelerating cavities of the ERL for FEL of the Siberian center of SR and THz Radiation, SB RAS, Novosibirsk. The system of dividing is built on the basis of a rectangular waveguide, associated with each cavity of a coaxial line by the coaxial-to-waveguide adapter (CWA). It is shown that under a certain choice of waveguide sizes and CWA, the equivalent circuit of the CWA can be represented by a current source. The analysis of the properties of such a system has been carried out and shown its advantages. Also it is discussed the experimental results and the experience of the operation of the device. The article presents the basic design parameters of a waveguide divider 600 kW of continuous power, running at a frequency of 180.4 MHz

Supplying the Power Requirements to a Sensor Network Using Radio Frequency Power Transfer

Wireless power transmission is a method of supplying power to small electronic devices when there is no wired connection. One way to increase the range of these systems is to use a directional transmitting antenna, the problem with this approach is that power can only be transmitted through a narrow beam and directly forward, requiring the transmitter to always be aligned with the sensor node position. The work outlined in this article describes the design and testing of an autonomous radio frequency power transfer system that is capable of rotating the base transmitter to track the position of sensor nodes and transferring power to that sensor node. The system's base station monitors the node's energy levels and forms a charge queue to plan charging order and maintain energy levels of the nodes. Results show a radio frequency harvesting circuit with a measured S11 value of −31.5 dB and a conversion efficiency of 39.1%. Simulation and experimentation verified the level of power transfer and efficiency. The results of this work show a small network of three nodes with different storage types powered by a central base node.

Adaptive transcutaneous power delivery for an artificial anal sphincter system

For controlling anal incontinence, a novel artificial anal sphincter system with sensor feedback based on transcutaneous energy transmission was developed. The device mainly comprises an artificial anal sphincter, a wireless power supply subsystem, and a communication subsystem. A transcutaneous power delivery system employing a class-E power amplifier, based on the adaptive control technique, is discussed in this paper. Amplitude modulation of the class-E power amplifier is integrated in the system and applied for the adaptive transcutaneous power delivery. Optimization of the power transfer efficiency and the misalignment tolerance is obtained. Experiments show that the system is capable of delivering at least 150 mW, with a power transfer efficiency of 41% over a distance of 3 cm, which can meet the electric power requirements of the artificial anal sphincter system. The power transfer frequency is 760 kHz.

An inductive power system with integrated bi-directional data-transmission

An inductive powering system is presented, capable of remotely powering implantable monitoring and stimulating devices. The system is capable of delivering at least 50 mW, with an efficiency of 36% over a distance of 3 cm. The power transfer frequency is 700 kHz. Optimisation of the power transfer efficiency and the misalignment tolerance was obtained using a self-developed design tool. Bi-directional data-transmission is integrated in the system: amplitude modulation is applied for the downlink transmission, absorption modulation for the uplink transmission. Our new system is capable of transmitting data at a maximal bit rate of 60,000 bits/s.

A comparison of minimum propagation delay and unity power transfer frequency of submicron MOSFETs

A comparison of minimum propagation delay and unity power transfer frequency of submicron MOSFETs