Note on Apple Experience with Wireless Power Charging
Wireless charging uses inductive or capacitive technology to transfer power from the pad to smart phone. The charging pad and phone contain wire coils. Charging pad coils are transmitting and phone coils are receiving. Transmitting coils draw current from the power source and transmit to the coils in your phone.
If the receiving coil and transmitting coil are perfectly aligned (directly coupled) efficiency of power transfer could be higher than 96%+. If they are not perfectly aligned (indirectly coupled) efficiency goes down drastically and the wasted energy turns to heat which must be dissipated. Having multiple transmitting coils (normally three) increases efficiency but still not as good as directly coupled.
There are other issues like EMC that need to be resolved but those are standard electronic issues.
Now Apples plan seems to have been, based on their patent filings, to use multiple coils as shown below.
Using multiple charging coils Apple (I assume) was trying to create one large charging surface. Other than EMC the main challenge is current that needed to be pumped to transfer power any place on the pad at high efficiency. However, power losses turning to heat would still need to be quickly dissipated.
Refer Joanna Stern’s article ‘Apple’s Fix for Charging Hits the Laws of Physics in the Wall Street Journal. Cannot comment on Apple’s experience but other companies who are perfecting high power (< 250 W) wireless power transfer like Eggotronic, Power by Proxi, Po. Powercast, COTA and others. However, believe most of them are going for directly coupled, inductive or capacitive, wireless power transfer or charging.
Wireless Power Transfer (WPT) technologies allow to deliver power to any compatible device with no need of power cords that connect the source to the load.
All these WPT systems are based on inductive coupling between transmitter and receiver, sometimes exploiting resonance or near field, and allow to transmit power from few mm up to a few tens of cm in near field systems. One of the practical limitations in inductive WPT is that they do indeed require an almost perfect alignment between TX and RX.
Near field WPT systems could overcome such a problem, but they have certification problems due to EMI and potentially health hazard.
Application – In Car Seat Application for Level 3+ Semi-Autonomous and Autonomous Vehicles:
Electromagnetic induction distributes an electrical power current directly to modules, without any physical contact. It allows modules 
to be Contactless and slide-able by threading modules into a loop with one single 14 AWG stranded wire. Currently technology is being used for AC power but can be designed for DC.
Wireless Power transfer between seat receiver and transmitter integrated in the base plate under the moving seat. The concept will be as below but for maximum efficiency may need 2 to 4 transmitters to achieve 75%+ power transfer efficiency.
Rolling contact in seat rail to transfer power to seat module. Snaptron contacts or spring brushed contacts and other technology innovations is the key.
Eggtronic Capacitive Technology is nothing like the inductive WPT. It uses the capacitive coupling between conductive plates kept at a certain distance one from another with a dielectric material in between (e.g. air), thus exploiting the electric field in place of the magnetic field.
The capacitive technology has many advantages, especially in terms of:
- Efficiency: the efficiency is very high, because a capacitive WPT is not affected by a series of loss mechanisms typical of inductive systems, such as losses in the ferromagnetic material for hysteresis, Eddy currents or skin effect in the winding wire.
- EMI: the field is strictly confined in the volume between transmitting and receiving plates, so virtually there are no emissions.
- Volume: the TX circuit is very simple and compact
- Thickness: plates are extremely thin (<100um), the conductive layer can be plated in a structural support to get the smaller thickness possible
- Free positioning: it is very simple to achieve free positioning with a proper design of the transmitting and receiving plates (e.g. matrix layout)
- Robustness to scratches and localized damages: considering a matrix- based layout, even if one or more elements are damaged the TX can still work fine everywhere but in the damaged elements.
- Data transfer: being the capacitor a high-pass physical channel, it can reach a very high data transfer speed, comparable to the fastest wired buses currently available on the market.
- Low cost: the transmitting and receiving plates can be made with well- known and cost-effective manufacturing processes such as electroplating.
The oscillator block shown below represents the resonant high-
frequency circuit patented by Eggtronic’s to drive the capacitors created by the TX and RX plates tight together. The power transferred in the secondary through the C capacitances is collected by the RX plates and rectified to get a DC voltage for the load RL.
Eggtronic Concept #1 – Capacitive Seat:
The first proposal is a skid-mounted seat, able to move along the whole rail and simultaneously rotate on a central pivot.
As opposed to current standard seat disposition and movement capabilities, the capacitive seat allows a complete new freedom of seat movement in the next generation car, removing at the same time the need for cables and all the inconveniences that come from their presence (wear, space, cost).
In this concept, each seat is now able to move freely and independently on the direction of the green arrows in Figure below and at the same time to rotate clockwise or counterclockwise by any degree.
Mechanical constraints to movement can be embedded by system design. The capacitive technology is installed in the rail, in the seat structure and in the central pivot. Each seat is totally plug & play.
The rail embeds a capacitive transmitter.
The seat embeds both a receiver (to get power from the rail) and a transmitter (to transfer power to the central pivot).
The central pivot embeds a receiver to get power during the rotational movement of the seat itself.
The capacitive system is also capable of high bandwidth data transfer. Signals can be transferred to the seat directly from the main car BUS.
Features
- Remove dozens of cables from seats
- Reliable, no wear
- Free movement along the Y-axis
- Rotation (clockwise & counterclockwise)
- Receive signals/commands (for seat adjustment)
- Receive power to activate the actuators (for seat adjustment)
- Total plug & play seats.
Eggtronic’s Concept #2 – Capacitive Chassis:
This concept takes the capacitive application to the next level.
The whole inner car chassis embeds an extremely thin capacitive layer that can be used to transfer both power and data to every electrical/electronic component of the car, with no need of using any cables. Seats get power and data from the layer below and can move freely in the car
We have already studied smart & autonomous anchoring systems able to ensure maximum reliability and compliance to safety regulations.
For more information contact designhmi@gmail.com or Eggtronic at maurizio.persico@eggtronic.com.
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Recommend you click Wireless Power Transfer and Charging for additional information.
Wireless Charging and Power Transfer is known to all today. This paper is summary few innovators in this technology eco-system.
MagMIMO MIT’s new long-range wireless charging tech that works like WIFI as for current in market products you still must get your device close to the charger for it to work – refer 
https://www.extremetech.com. Innovations like Qi 1.2 promise to extend the range of wireless charging, but a team at MIT has unveiled a new wireless charging tech called MagMIMO. If this system can be perfected, you might not even have to take the phone out of your pocket to charge it — MagMIMO will simply detect the phone and project a cone of energy toward it to connect.
The version of MagMIMO current working in the lab can charge a phone from up to 30 cm (almost a foot) away. That compares with a little over 1 cm with current Qi-compatible chargers, and 4.5 cm with the upcoming 1.2 revision of Qi
ReVive is a low cost, easy to install, FLIway charging pad for your car that provides 36-watts of power, which is significantly higher than others.
For Power transfer though ceiling tiles please click Design HMI report out on COTA Tiles from 2017 CES. Click COTA – OSSIA Wireless Charging / Power Transfer
The advantages to products that work on wireless electricity are enormous in auto for charging electric cars and transferring power between power cords and in car assemblies. Another example could be supplying power to a rotating object like a wheel: with wireless electricity with no wires to tangle or break, and no slip contacts to wear out.
The ways in which wireless power transfer could improve design and make products smarter, smaller and more effective – both in function and cost – are almost endless.
Qi-compliant wireless power transfer receivers and transmitter circuits. The bq500410a is a Texas Instruments transmitter IC. Companion receiver ICs include the bq51050B, bq51051B, bq51011, bq5013, bq51013A, and bq51013B.
