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hamonic
Thank you for your advice, I think my motors can work from the driver.
it comes my interested to understand the logic and calculation.
let say, my single motor require 2.8V 1.68A.
If I have 12v PSU, the current I need for this motor is proportional to PSU, which is (2.8/12)×1.68A=392mA
and for same logic if using 24V, the calculation is (2.8/24)×1.68A=196ma
Above is correct situation for the driver work?
If you ran the motors at maximum current and the drivers were 100% efficient, that would be true. But you will run the motors at less than maximum current, because you don't need the full torque and they get very hot at full current. Also the drivers are not 100% efficient, more like 90%.
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hamonic
I though the driver would regulate power to the need/requirement of individual motor, even the input power is 12 or 24 or whatever voltage. Which mean if the motor need 2.8V, then the driver would automatically adjust voltage from 12 or 24V down to 2.8V, isn't it correct?
Correct, although the 2.8V is just the average voltage. In reality it will be switching rapidly between +12V and -12V, or +24V and -24V..
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hamonic
Another interesting question is,
for total power from PSU, if I am about making a super large print platform, something like 1meter by 1 meter hotbed, then I may need to have PSU exceed 120W x 25= 3000w (multiply by 25 because one regular hotbed is 200mm by 200mm, 1meter × 1meter is about 5×5=25piece of regular hotbed size)
do you think the mainboard can support that much power?
for people making that big platform, which kind of board can be an option?
For large heated beds, AC mains heating power is the practical solution. The mainboard is then used to drive a zero-crossig solid state relay (SSR), which in turn drives the bed heater. So the 12V or 24V power supply no longer has to drive the heated bed, just the hot end heaters, motors, electronics, fans etc. My printer with a 330mm diameter bed uses AC mains power for the bed heater, and a 12V 100W PSU for everything else. Of course, you need to take additional safety precautions when using AC mains voltage for the bed heater.