As I'm trying to get the whole picture I've had to dip into the electronic side of things. Now I've got offers for steppers, drives and torodial transformers, but I'm a bit unsure on how to size them properly, or specifically how to size the PSU. The specs are as follows:

- NEMA 24 closed loop steppers at 4.5Nm holding torque, 5A, 0.75ohms, 2.4mH (all phase values).
- Drives rated at 20-70VAC or 30-100VDC, 8A peak.
- 420W torodial transformer 220 to 70 VAC, 6 A

Firstly, as the drives can take AC, is there any need to convert the output current from the torodial transformer to DC? As I've understood in case I go for AC to AC I could simply connect the first winding to the mains (with fuse for safety) and the second directly to the drives? Also, assuming no DC conversion, is it safe to use a 70VAC rated torodial transformer to power the drives rated at max 70VAC?

Now, if I've understood correctly the total amps my 4 steppers will draw is roughly 2/3 of the sum of the rated amps of the steppers, i.e. 4*5A*2/3=13,33A. So the PSU would have to supply (rounded up) at least 14A? As the torodial transformer is rated at only 6A, should I consider wiring several in parallel to get more amps or would it be better to simply look for a beefier one to supply all the current i need?

And so the voltage. This has me the most confused, some recommend to not over do the voltage for fear of getting components burnt, while others prefer higher voltages in order to not lose out on max performance (however, in these cases drives usually have some sort of voltage regulators). Now, if I've done the math correctly the Vmax of my parallel wired steppers is 32*√(2.4mH) = 49.6V., so well within the 70VAC outputted by the torodial transformer so as to get the most out of the steppers, BUT (and see first question above) would I run the risk of overheating my drives/steppers with this setup? The drives I've been offered (Lichuan LCDA86H) do list "overvoltage protection", but this sounds to me more like a fuse type protection than active voltage regulation.