I am currently working on a 3 phase energy meter project. I don't have a lot of experience in designing power supply circuits (AC/DC) let alone a 3 phase 4 wire one (L1,L2,L3 and N) with a transformer to be galvanically isolated. Since energy measurement is being done for all three phases, the metrology (Microcontroller + metering IC) part must be able to measure energy even if two phases go out, so AC supply must come from all three phases. I've scoured the internet and found a few approaches, some used a transformer, some didn't.
1. My findings
1. My findings
- A fellow user here asked the same question but had a cumbersome solution(3 transformers) and didnt want an isolated supply.
- TI and AD have a few application notes for whole energy meters but their power supplies are transformer-less (bummer).
- ST has a lineup called VIPER (rectification then flyback DC/DC) which has a transformer based schematic but for prototyping i think the design will take some time to perfect and i'm looking for a faster temporary solution to focus on the computing part of the system for now.
- Can i use something like this ( IRM-20-12 ) for the time being or if there is a better model please let me know. If the answer is yes then i think the next question is how do i connect it to all 3 phases since the power module only take Line and Neutral ?
- If the answer for the previous question is no, what would be my options for a prototyping stage and another for a cost efficient and not so brutal to design ?