Electromagnetic coil

About: Electromagnetic coil is a research topic. Over the lifetime, 187832 publications have been published within this topic receiving 1168432 citations. The topic is also known as: electromagnetic coil.

Transponder with overlapping coil antennas on a common core

Abstract: A wireless device includes an antenna assembly, including a core and one or more power coils, wound around the core on respective power coil axes, including at least a first power coil having a first power coil axis. One or more signal coils are wound around the core on respective signal coil axes, including at least a first signal coil wound so as to overlap the first power coil, the first signal coil having a first signal coil axis that is substantially parallel to the first power coil axis. Power circuitry is coupled to the power coils so as to receive therefrom first radio signals in a first frequency band, and to rectify the first radio signals so as to generate a direct current. Communication circuitry, powered by the direct current, is coupled to perform at least one of transmitting and receiving second radio signals in a second frequency band via the signal coils.

Formulas for the Skin Effect

Abstract: At radio frequencies, the penetration of currents and magnetic fields into the surface of conductors is governed by the skin effect. Many formulas are simplified if expressed in terms of the "depth of penetration," which has merely the dimension of length but involves the frequency and the conductivity and permeability of the conductive material. Another useful parameter is the "surface resistivity" determined by the skin effect, which has simply the dimension of resistance. These parameters are given for representative metals by a convenient chart covering a wide range of frequency. The "incremental-inductance rule" is given for determining not only the effective resistance of a circuit but also the added resistance caused by conductors in the neighborhood of the circuit. Simple formulas are given for the resistance of wires, transmission lines, and coils; for the shielding effect of sheet metal; for the resistance caused by a plane or cylindrical shield near a coil; and for the properties of a transformer with a laminated iron core.

Power source, charging system, and inductive receiver for mobile devices

Abstract: A power source, charging system, and inductive receiver for mobile devices. A pad or similar base unit comprises a primary, which creates a magnetic field by applying an alternating current to a winding, coil, or any type of current carrying wire. A receiver comprises a means for receiving the energy from the alternating magnetic field and transferring it to a mobile or other device. The receiver can also comprise electronic components or logic to set the voltage and current to the appropriate levels required by the mobile device, or to communicate information or data to and from the pad. The system may also incorporate efficiency measures that improve the efficiency of power transfer between the charger and receiver.

Apparatus and method for restricting the discharge of fasteners from a tool

Abstract: A device for discharging fastening elements, and a method of preventing a device from discharging fastening devices into human flesh, are disclosed. The device includes a coil proximate a location of discharge, a capacitive element coupled in parallel with the conductive coil to form a resonant tank circuit, an oscillator that drives the tank circuit, a frequency detector, an amplitude control circuit and a processor. The detector detects a frequency of oscillation of the tank circuit as affected by a material proximate the coil. In response to an electrical signal from the oscillator, the control circuit generates a control signal that is provided back to the oscillator. Based upon the frequency and an additional signal functionally related to the control signal, the processor provides an output signal that prevents the device from discharging when the material proximate the coil is human flesh.

Modern Advances in Wireless Power Transfer Systems for Roadway Powered Electric Vehicles

Abstract: Wireless power transfer system (WPTS)-based wireless electric vehicles, classified into roadway-powered electric vehicles (RPEVs) and stationary charging electric vehicles (SCEVs), are in the spotlight as future mainstream transportations. RPEVs are free from serious battery problems such as large, heavy, and expensive battery packs and long charging time because they get power directly from the road while moving. The power transfer capacity, efficiency, lateral tolerance, electromagnetic field, air-gap, size, weight, and cost of the WPTSs have been improved by virtues of innovative semiconductor switches, better coil designs, roadway construction techniques, and higher operating frequency. Recent advances in WPTSs for RPEVs are summarized in this review paper. The fifth- and sixth-generation online electric vehicles, which reduce infrastructure cost for commercialization, and the interoperability between RPEVs and SCEVs are addressed in detail in this paper. Major milestones of the developments of other RPEVs are also summarized. The rest of this paper deals with a few important technical issues such as coil structures, power supply schemes, and segmentation switching techniques of a lumped inductive power transfer system for RPEVs.