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I'm currently working on a project involving three 90V 5A DC stepper motors controlled by G320 Geckodrives and powered using a single 90VDC 13.5A power supply. I'm working with a mentor who suggested I use a rack of 250V electrolytic capacitors to manage the peak currents drawn by the motors. I imagine that these capacitors would be placed across the power terminals of the Geckodrives and I understand that in this configuration at full charge the capacitors would maintain a constant 90V but I'm not sure how they would help manage current. If anyone has an explanation to this concept or can steer me in the right direction that would be greatly appreciated. I also wanted to ask what is a typical charge time for the capacitors to design for?

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  • \$\begingroup\$ If the peak current is higher than 13.5A, but the average current is lower than 13.5A, then the capacitors could help to supply the current that cannot be supplied by the supply. \$\endgroup\$
    – user57037
    Commented Apr 12, 2016 at 3:07

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I don't see any benefit in using 250V capacitors if the supply voltage is only 90VDC, it's waste of money. I have installed Sanyo Denki motors with RTA drive, where in manual says: $$C=\sqrt{N}*C_{min}$$, where N is the number of drivers and $$C_{min}=4.7mF$$, therefore approx 8 mili farad is required.
http://www.metalwork.it/download/manual/PLSAME04.pdf

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  • \$\begingroup\$ Wouldn't there be enough back emf generated, at times, to bump the voltage in a surge to double the normal voltage? and your formula is for capacitance, not voltage. \$\endgroup\$ Commented Apr 11, 2016 at 23:53

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