I am currently trying to build the Wireless Charging Platform from scratch using Arduinos for my school project. The project requires 42 transmitter coils to be connected to a central processor and will be transmitting power by resonant coupling and also will be sending/receiving analog ping signals to receiver coil. The original idea was to use I2C connections on RPi4 but I learned very quickly that RPIs dont have analog io pins.
Furthermore, the typical coupling frequency for transmitter coils is 100khz. I was wondering if Arduino's can output such signals or I have to create a module.
Has anyone worked with such number of IO on Arduino? Which Arduino should I use?
That's too fast for a "regular" ATmega Arduino, especially 42 "channels" at the same time. I really don't know if any of the faster versions can handle it.
With slower signals or with a faster processor you can use an analog multiplexer to switch and read multiple analog inputs. I don't think you'll find one with 42 inputs but they can be combined and "expanded". (The ATmega chip actually has only has one ADC, multiplexed to multiple analog input pins.)
I don't know this works or exactly what you need to measure, but if you can rectify & filter the AC it will be easier and you don't have to read so fast. If you have enough voltage you may be able to use regular diode (or a Schottky diode) but you might need precision rectifier circuits made with op-amps and 42 of them would be a lot of circuitry!
Start with one coil on one Arduino. Make that work.
Then see how many coils you can sensibly connect to one Arduino - mind that you don't want very long cables between the coils and the Arduino. Physical size is a restraint as much as I/O ports and processing power are.
Have that Arduino talk to a central computer.
Then get enough Arduinos to do all those coils (by now it's getting easy).
Considering it's pumped into a coil, I think that very coil will act as an excellent filter to make it a sine. I think it will work just fine. I wouldn't be surprised if those coils are normally driven by a square wave to begin with, it is after all pretty common to drive coils with a square wave: such as inductors in buck converters, and transformers in switching power supplies, or even using an Arduino's PWM output to generate sound from a speaker.
100 kHz is indeed no problem for an Arduino. You just have to tweak the registers in order to get a clean 50% duty cycle.
All true, but missing the point. The OP needs to supply POWER, not a signal. There is NO power in a square wave. Consider computing the power delivered in a square wave. But we will see when the device is completed.
This is true. To add a bit more, I am transferring power over magnetic coupling. Its a little different from average induction and adds another dimension of frequency. I was concerned about the fact that Arduino's pins may not have enough power also.
Uh what? A square wave has more power (+3 dB more) than a sine wave of the same peak amplitude. The additional power is in all of the odd harmonics. It's not uncommon for power inverters to produce square waves or modified sine wave.
A quick Google search shows that there is more to wireless phone charging than just powering a coil. There are special breakout boards available, with processor and all the components.
Leo..
I need a processor to check responses from the receivers and also send power to the transmitter coils. I thought it would be best to have a central control because then I just need to write one big program. However, I have thought of using multiple Arduino or Micro processors in parallel?
What data transfer?
WPC standards have object detection protocols and this is done by sending analog packets between to receiver coil and transmitter coil to control the power level. I don't remember the structure at the top of my head but it is similar to computer network protocols, just analog and communicated wirelessly
How much power will you require from a power supply?
For now I believe 5W from one coil would be sufficient. The first step is to make the transmitter coil array to work with one receiver which is typically 5W. However, the final product may consume way over 5W as it can charge multiple receiver coils. Yet this post is just for my prototype so one receiver.
My Electronics, programming, Arduino, hardware experience is pretty limited. I have done extensive programming on C++, Python, and Matlab, but I never programmed for an Arduino. I have designed and tested a couple of hardware such as an audio amplifier but never took on a project like this one. Btw this is my senior capstone project. Imagine your average EE undergraduate level of knowledge and experience.
Yeah I can simply use the ones they provide, but Im trying to make the charging platform by Tesla and they use a coil array. I don't think I can integrate the breakout boards to the circuit because they were design to be used with one coil, instead of 42...
So in order to make a position free wireless charger, you need to have 3 layers of coil. My project will have 14 coils each layer so 42 coils.
The ping signals is a rough description of the info-packets that are being communicated between the wireless charger and receiver (phone) to make sure its receiving the right power level. It also functions as a way to tell that the object being charged is a receiver. Or else, eddy current and safety concerns.
