I am designing a Power Line Communication Network which has to power several LED lights, which will be consuming top 5A of current, and send their control information, RGB values for each light. The data rate does not need to be very high, 5kbps is enough. The modulation scheme is not designed yet, I am first evaluating the electrical technological feasibility. Therefore, I am planning on designing just specifying a frequency range where the data will be transmitted. The higher the frequency, the easier it is to distinguish the supply (Low frequency) from the data (high frequency), so I set a minimum frequency the data spectrum will occupy.
The application requirements are:
- 12V DC PLC or 24V AC PLC
- Max DC current: 5A
- Data minimum frequency: Flexible, but I'd like it to be around 100kHz (or less).
- Min Data Rate: 100bps
- As cheap as possible
The power supply side will be something like this, with a microcontroller generating the modulated data to send:
(Could also be an AC supply)
The main design challenge is the electrical summing operation to form the Supply+data PLC signal. Initially I wanted to use the MAX20340 IC, but it can't handle the current this application needs.
As a first approach, I am following this answer, the DC supply goes to a LPF, the data through a HPF and I get the superposition. I simulated that in LTSpice, being the filters a simple inductor and capacitor:
I think something like this could work, but I am not sure. For example, the gain peak caused by the LC resonation may cause problems. I'm also not familiarized with PLC-specific implementation problems. I thought about removing the inductor, what specs of the voltage source should I check to see if this is possible? I only thought about it's output impedance, which in this case I'd like it to be non-zero, but with the currents I'm handling I don't think this is really an option.
Another option I saw is using a transformer, but not in the PLC context. I'm not sure if I can isolate the data generation block's GND from the power supply GND.
I also saw PLC is used in Power Over Ethernet (POE), and that there they also use transformers, but using 4 instead of 2 wires: Source: https://kintronics.com/how-power-over-ethernet-works/
To sum up, I've thrown everything I've seen so far, but:
- I'm pretty lost when it comes to deciding if what I'm seeing is a viable solution or not.
- What aspects of the solution I choose should I analyze to know I won't have problems when implementing this.
As a side-comment, I read this answer and freaked out, that's why I am really doubtful about the solution I choose working in real life.
Edit1: I added the possibility of using AC supply and communication instead of DC, but I haven't researched it yet.
Edit2: I lowered the bit rate requirement to 100bps, I realized I could manage to work with this really low speed. This allows me to consider for example the X-10 protocol.