On Sat, 28 Mar 2015, Bertho Stultiens wrote: > On 03/28/2015 08:37 PM, kqt4a...@gmail.com wrote: >> I have a question about the voltage to drive a stepper motor >> 12 volts works but higher voltages make the motor weaker >> I am building a simple stepper driver >> A nema 23 2.7 amp stepper motor and 36 volt power supply >> The controls are hand held, forward ,reverse, stop, and speed >> I built the controls and driver using a 12 volt battery to test >> Now I completed the project and am using the 36 volt supply >> The motor runs at the same speed but it is so weak I can hold the shaft and >> stall the motor >> This is also the same with 36 and 24 volt batteries >> With a 12 volt battery I can not stall the motor >> I am using http://piclist.com/techref/io/stepper/SLAm/SLAm_bld.htm and an >> Arduino >> I would be happy if someone would point out my stupidity > > > The chip uses a constant current setup using PWM. When you raise the > supply voltage then the trip-current is reached sooner and recovery may > take too long for the next PWM cycle. > > The datasheet says that the off-time is between 7 and 12 microseconds. > Your high voltage level may cause a feed-through on the current-limiter > because of the increased rising flank of the current. This decreases the > on-time vs off-time and the effective current to the motor is reduced > which results in a lower torque. > > The problem may be in the physical setup, where too much noise is > propagated. You should check the wiring and use an oscilloscope to check > the signals for spikes etc.. >
I do not have an oscilloscope and I don't think noise is the problem I am single and it is usually pretty quiet around here :) ------------------------------------------------------------------------------ Dive into the World of Parallel Programming The Go Parallel Website, sponsored by Intel and developed in partnership with Slashdot Media, is your hub for all things parallel software development, from weekly thought leadership blogs to news, videos, case studies, tutorials and more. Take a look and join the conversation now. http://goparallel.sourceforge.net/ _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
