Radiated Power ?
The energy is transferred with a pure magnetic field, not to be confused with radiative systems or radio waves.
The effective radiated power, responsible for the range of radio, is determined with the product of the electric- and the magnetic field-components which are perpendicular in polarization.
With Wireless Energy, this far-field electric field and the radiated power are almost zero, far below the RF-radiation limits for industrial equipment.
Such decaying magnetic fields can be generated with antenna coils much smaller than the wavelength,
with a low feed-impedance, balanced and eventually shielded to prevent emission of electric fields.
Electric power is coupled from transmit-coil to receiver-coil by pure inductive coupling.
The coupling-factor, defined as the part of the transmit-flux which passes at the receiver-coil,
can be very low compared to transformers, usual between 0.01 or 0.1.
The low coupling-factor is compensated with low loss, or resonance with high Q-factors in both coils.
The receiver-coil should be precisely tuned, which can be a challenge in mass-production.
With precise tuning the power-efficiency is substantially higher than the coupling-factor.
Unique matching circuits provides power-transfer independent on tuning and coupling.
Comparable with Qi or PMA ?
With these popular Wireless-energy standards, the coils are not tuned in resonance. The power-efficiency and range are limited by the coupling-factor. These systems are not more than switching converters, where the transformer is split apart in 2 parts, primary and secondary. A necessary fixed coupling limits the distance between the primary and secondary coil of the transformer in both parts.
In our wireless-energy solutions resonance with high Q-factors is an important part of the system.
Magnetic resonance not only compensates the effects of low coupling-factor, but also limits the emission-spectrum to one single working-frequency, where the harmonics originating from drivers and rectifiers are filtered. At ISM-frequencies more radiation and magnetic fields-strengths are possible without interference to other systems. Magnetic resonance will be incorporated by PMA, with A4WP.
The power from the magnetic field is only available within a limited distance around the antenna. This range is determined with its dimensions and shape. Outside this range the field-strength will decrease rapidly with distance in the 3rd or 4th power, as long as the effective radiated power is zero. At a distance equal the size of the antenna´s, an overall power-efficiency of 90% or better is possible.
With advanced antenna-design, the magnetic field can be zero at specified distances and directions, to prevent unwanted couplings to sensitive electronics.
We can make wireless-energy systems for any distance, greater than antenna-size, and different from any standard.
— Medical implants
— Industrial sensors
— RFID-chips with extra power
— Wireless table-lights
— Floating Lamp
— Battery chargers:
Inductive charging without cables and connectors can be more reliable and easy.
With the antennas integrated on PCB´s, no power-cables are needed at all.