Hello! I'm working on a project about positioning an RC car relative to a wireless charger. In the RC car, I will install a coil receiver and the car will move on the Qi standard wireless charger. Therefore, the question is, do you know of any sensor that can read changes in the strength of the magnetic field on the receiving coil during movement around Qi wireless charger?
An ADC can read the voltage across the coil, the peak magnitude of which is proportional to the strength of the magnetic field. Changing geometry will also affect the peak value, though.
The voltage will be AC and so must be offset for DC measurements.
thank you for your reply, but I don't understand the last sentence. I thought the voltage on the coil would be DC.
The field is AC from the charger and is received as such. Look at it as an air core transformer. The voltage in the secondary (your car) will be AC. Realize you will have to convert this to DC to charge the battery so measuring this voltage will give you a relative signal strength. It will change as the charge of the batteries changes. You might want to disconnect the charge circuit or place it in a constant current mode to make the measurement. If you want to measure the coil directly it is an AC voltage where one of the leads from the antenna goes plus and minus referencing the other lead.
Detecting the charge station from some distance looks hard to me. At a very short distance, yes. Better an IR transmitter on the charger and an IR receiver on the car.
I'm not sure if a hall effect sensor is accurate enough for this application, but if you use a 1 or 3 axis fluxgate magnetometer it's definitely possible. Note that you would first need to know the baseline magnetic field of the area the car is in plus what direction the magnetometer is facing relative to the car (i.e. how it's mounted).
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