I bit of information from Polulu's web site. They say.. "*While VNH3SP30’s over-voltage shutoff doesn’t activate until 36 V, in our experience, shoot-through currents make PWM operation impractical above 16 V.*"
This seems reasonable for the intended automotive use case where a lead/acid battery is supplying the power. but there may be transient up to 3X the nominal battery voltage. I've never run these using more than the nominal 15.7 volts I get from a fully charged LiPo battery and when bench testing I use a 12 volt power supply that does about 13.5 volts. Try running your motor on 12 volts I think the way to go is to just buy from Polulu and not try to sav $2 on eBay. Polulu actually offers support Here is one that seems to actually handle higher volts https://www.pololu.com/product/1457 Or you just buy four MOSFETS and build you own switch Another one I was not going to recommend because of the cost is really excellent and again their support os excellent. I had a problem and they offered to replace the unit. They will also talk with you about software. But you pay for the support in the product price. This unit has input from the quadrature encoders and runs the PID loop itself. The computer (That would be some HAL component in LCNC) sends only the desired position or the desired velocity of one of the interfaces. There are a few to choose from, RS232, USB, PWM and analog. ThePID has an autotune feature that can get you in the ball-park I use one of these to drive a mobile robot's traction motors. It pushes a lot of complexity out of my control computer because this controller does the encoder processing and PID control . But these are $90 devices and I've switched to using these https://protosupplies.com/product/vnh2sp30-dual-monster-motor-shield/ The above is the EXCELLENT tutorial on using the VNH3SP30 chip and the dual-chip version attached to an Arduino-like board with zero wires or solder. It just plugs in. But I buy the dual-chip boards from China for $7 each. Much cheaper than the 90 Roboclaw units. These dual-chip drivers are widely cloned because the design is Open Sourced. The Egle design files are available So my now-standard motion control setup is one of these: ebay.com/itm/Dual-VNH3ASP30-... <https://www.ebay.com/itm/Dual-VNH3ASP30-replace-VNH2SP30-Stepper-Driver-Module-30A-Monster-Moto-Shield/291549918162?hash=item43e1bab3d2:g:14wAAOSwVb5d8guN> plugged into one of these you can get for about $14. www.st.com/en/evaluation-tools/nucleo-f446re.html My experience is that I can drive this with a lipo battery for hours and the chips are not even warm. That may change as my current project is a Kidie car conversion. It is the kind of toy car that hold two 6-year old kids and goes up to 6 MPH on the sidewalk. Fisher-price sells them www.target.com/p/power-wheels-tough-talking-jeep-powered-ride-on-black-red <https://www.target.com/p/power-wheels-tough-talking-jeep-powered-ride-on-black-red/-/A-53016862#lnk=sametab> The car is being adapted to autonomous self-drive and will do laps around the block with no driver. These VNH3SP30 chips (and the nucleo-f446re) will power the rear drive wheels. The car's total weight (including a lead/acid marine battery) is about 100 pounds. The driver chips really can handle maybe 100W per chip or 50W continuous On Wed, Oct 28, 2020 at 1:04 AM Gene Heskett <ghesk...@shentel.net> wrote: > On Tuesday 27 October 2020 09:33:41 Gene Heskett wrote: > > Hooked up the 420 watt driver. Can't find any input high pass filter, > so I am feeding it a low frequency square wave of up to 80 mv peak to > peak. It took a couple hours of diligent net search to find a copy of > that chips docs. Apparently the car amplifier folks still think, 5 years > after this chip was first shipped, class D is still a proprietary > secret. Rated at 33db of gain, an 80 mv signal should drive it halfway > to the rails. > > AC from a big toroid power tranny is about 53 volts with a grounded > center tap, shows about 10 volts per rail less that the 42 volt warning > some guy on u-tube claimed. > > From the lack of input filter, I get the impression this thing will > amplify a dc error. But the output is both low and noisy, and both > terminals are in phase. Which makes zero sense. Running its class D at > 250 kilohertz, and zero drive, the heat sink sits at 126F and doesn't > get a lot warmer with 2 or 3 volts of drive. And while it might make the > motor tick occasionally, it doesn't move the motor. Rated to drive > speakers down to 2 ohms, 4 preferred, 8 tolerable, this motor is 2.7 > ohms stopped. Ought to be right at home. So the results are "puzzling". > > Previous playing with the 150 watt driver says it can absolutely hammer > that motor, but with a single ended supply, it has a high pass filter in > its input so it can be driven with ground referenced audio. > I'll play some more, and read the 42 page doc I found for clues after > I've gotten some more sleep time. > > Cheers, Gene Heskett > -- > "There are four boxes to be used in defense of liberty: > soap, ballot, jury, and ammo. Please use in that order." > -Ed Howdershelt (Author) > If we desire respect for the law, we must first make the law respectable. > - Louis D. Brandeis > Genes Web page <http://geneslinuxbox.net:6309/gene> > > > _______________________________________________ > Emc-users mailing list > Emc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/emc-users > -- Chris Albertson Redondo Beach, California _______________________________________________ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
