For many years, I designed three-phase high power circuits.
When a mistake is made (even a trivial one), the circuit literally blows up and almost everything in it is destroyed. People could be hurt. The driven motor could be damaged. Seldom there are second chances with power electronics, like on a logic circuit.
I would strongly suggest, that you name consistently every single component in the signal path. That includes the variable labels in software, ports, the analog channels, boards and of course the drivers and the power SCRs.
You could use any label you want, but I would use the standard three-phase nomenclature used in the country where you live, i.e: R,S,T or U,V,W or L1,L2,L3 or R,Y B.