Post by thread:[OT]: Need ideas for supply for 90V motor drive...

Once again, I'm not looking for anyone to do my work for me - just hoping someone can give me a little push down the hill. I'm after the lowest cost way to make the 90V needed for a brush motor PWM speed control w/ current limit.....Any ideas as to where I might start looking? TA, Chris -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email spam_OUTlistservTakeThisOuTmitvma.mit.edu with SET PICList DIGEST in the body

Chris Loiacono wrote: > Once again, I'm not looking for anyone to do my work for me - just hoping > someone can give me a little push down the hill. > I'm after the lowest cost way to make the 90V needed for a brush motor PWM > speed control w/ current limit.....Any ideas as to where I might start > looking? You want to make the 90V, or the controller, or both? If you want to make the 90V, then what are you starting with? Do you want bidirectional operation? What type of motor is it? -- Mike Poulton .....mpoultonKILLspam@spam@mtptech.com MTP Technologies KC0LLX -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listservKILLspammitvma.mit.edu with SET PICList DIGEST in the body

I'm looking for nearly the same thing but for a 30-volt, 15-amp reverse capable PWM speed controller for brushed-DC permanent magnet type motors. The +-30V is going to be supplied by a big ni-cd pack. I've looked around on the PIClist site and found some promising things but they seem to lack reversability. Ideally, it'd be able to brake the motors with a PWM-to-ground short circuit type mechanism instead of trying to apply opposing voltage to get the motors to stop. Maybe someone else has already done this exact thing. Gladly take any suggestions! Chris Loiacono wrote: > Once again, I'm not looking for anyone to do my work for me - just > hoping someone can give me a little push down the hill. I'm after the > lowest cost way to make the 90V needed for a brush motor PWM speed > control w/ current limit.....Any ideas as to where I might start > looking? -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email .....listservKILLspam.....mitvma.mit.edu with SET PICList DIGEST in the body

At 05:21 PM 11/21/02 -0500, you wrote: >Once again, I'm not looking for anyone to do my work for me - just hoping >someone can give me a little push down the hill. Right there behind you. ;-) >I'm after the lowest cost way to make the 90V needed for a brush motor PWM >speed control w/ current limit.....Any ideas as to where I might start >looking? From 120VAC? FW bridge with appropriate fusing and surge suppression and EMI filtering, followed by a BFC filter. Limit the duty cycle of your PWM to less than about 55 or 60%. Optically isolate the PIC (presumably, eh?) controller and power it from a separate transformer power supply if possible. Best regards, Spehro Pefhany --"it's the network..." "The Journey is the reward" EraseMEspeffspam_OUTTakeThisOuTinterlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listservspam_OUTmitvma.mit.edu with SET PICList DIGEST in the body

Take a look at http://www.robot-power.com/ and the Open Source Motor Control (OSMC). They have the design published for a PWM power unit that is a 160 A, 50V H-Bridge. They supply both the schematic and a kit. I purchased the kit and assembled it with no problem. Unit works good. While you may not want the kit, the schematic should help you design what you need. The PWM control is from an Intersil HIP4081PWM controller that controls external FETs for power. I used it in another project (zero shift focuser for my telescope). David V. Fansler @spam@DFanslerKILLspamMindSpring.com http://www.DV-Fansler.com {Original Message removed}

>I'm looking for nearly the same thing but for a 30-volt, 15-amp >reverse capable PWM speed controller for brushed-DC permanent >magnet type motors. The +-30V is going to be supplied by a big >ni-cd pack. >I've looked around on the PIClist site and found some promising things >but they seem to lack reversability. Ideally, it'd be able to brake the >motors with a PWM-to-ground short circuit type mechanism instead of >trying to apply opposing voltage to get the motors to stop. This is exactly the area that the Intersil HIP4080 is great for. Colleagues of mine are using these to build a PWM driver to go on space craft to operate from 29V supply. In our case we need 10A peak, but for your use just use beefier output FETs. You will have the advantage of being able to use the most recent fast switching/low input capacitance FETs that will suit. -- http://www.piclist.com hint: To leave the PICList KILLspampiclist-unsubscribe-requestKILLspammitvma.mit.edu

So, if I understnd you correctly, simply make DC from the line and since it will be more than 120V, limit the max pwm output to equal 90V.........is that what you mean? Certainly sounds inexpensive. I'll have to see how much resolution this will take away.... > From 120VAC? FW bridge with appropriate fusing and surge > suppression and > EMI filtering, followed by a BFC filter. Limit the duty cycle > of your PWM > to less than about 55 or 60%. Optically isolate the PIC > (presumably, eh?) > controller and power it from a separate transformer power > supply if possible. -- http://www.piclist.com hint: To leave the PICList RemoveMEpiclist-unsubscribe-requestTakeThisOuTmitvma.mit.edu

What's the load (5A? 50A?), and the required regulation (5%, 10%, in the neighborhood, etc)? If 10% under is ok, then make a full wave rectifier from AC mains. 120V RMS = 169.68V p-p Full wave with appropiately sized caps = ~84vdc -Adam Chris Loiacono wrote: {Quote hidden}>Once again, I'm not looking for anyone to do my work for me - just hoping >someone can give me a little push down the hill. > >I'm after the lowest cost way to make the 90V needed for a brush motor PWM >speed control w/ current limit.....Any ideas as to where I might start >looking? > >TA, >Chris > >-- >http://www.piclist.com#nomail Going offline? Don't AutoReply us! >email spamBeGonelistservspamBeGonemitvma.mit.edu with SET PICList DIGEST in the body > > > > > > > -- http://www.piclist.com hint: To leave the PICList TakeThisOuTpiclist-unsubscribe-requestEraseMEspam_OUTmitvma.mit.edu

I really like this idea.... almost too simple! The motor is a 1.75 HP gear motor. I'll have to check on the gear ratio to see if I can achieve the speed range in the spec. since it could be only 81V if the line is as low as 115VAC.... I don't have a specification for the regulation, but my guess is that it is in the 5 to 10% range since it is for a small roll converting machine.... {Quote hidden}> > What's the load (5A? 50A?), and the required regulation (5%, 10%, in > the neighborhood, etc)? > > If 10% under is ok, then make a full wave rectifier from AC mains. > > 120V RMS = 169.68V p-p > Full wave with appropiately sized caps = ~84vdc > > -Adam -- http://www.piclist.com hint: To leave the PICList RemoveMEpiclist-unsubscribe-requestTakeThisOuTmitvma.mit.edu

At 09:19 PM 11/22/02 -0500, you wrote: >What's the load (5A? 50A?), and the required regulation (5%, 10%, in >the neighborhood, etc)? > >If 10% under is ok, then make a full wave rectifier from AC mains. > >120V RMS = 169.68V p-p You're off by 2:1, it's about 340V p-p. Best regards, Spehro Pefhany --"it's the network..." "The Journey is the reward" speffEraseME.....interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com -- http://www.piclist.com hint: To leave the PICList EraseMEpiclist-unsubscribe-requestmitvma.mit.edu

> >What's the load (5A? 50A?), and the required regulation (5%, 10%, in > >the neighborhood, etc)? > > > >If 10% under is ok, then make a full wave rectifier from AC mains. > > > >120V RMS = 169.68V p-p > > You're off by 2:1, it's about 340V p-p. > And with full wave rectification and filtering there will be about 169.68VDC. Not good for the 90V motor ;-) Paul -- http://www.piclist.com hint: To leave the PICList RemoveMEpiclist-unsubscribe-requestEraseMEEraseMEmitvma.mit.edu

I think by "full wave rectification" he means using a center-taped transformer with two diodes, NOT a four diode bridge. That does indeed divide the voltage by two. Sean At 11:16 PM 11/22/2002 -0500, you wrote: {Quote hidden}> > >What's the load (5A? 50A?), and the required regulation (5%, 10%, in > > >the neighborhood, etc)? > > > > > >If 10% under is ok, then make a full wave rectifier from AC mains. > > > > > >120V RMS = 169.68V p-p > > > > You're off by 2:1, it's about 340V p-p. > > > >And with full wave rectification and filtering there will be about >169.68VDC. Not good for the 90V motor ;-) > >Paul > >-- >http://www.piclist.com hint: To leave the PICList >RemoveMEpiclist-unsubscribe-requestspam_OUTKILLspammitvma.mit.edu -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

At 05:21 PM 11/21/02 -0500, Chris Loiacono wrote: >Once again, I'm not looking for anyone to do my work for me - just hoping >someone can give me a little push down the hill. > >I'm after the lowest cost way to make the 90V needed for a brush motor PWM >speed control w/ current limit.....Any ideas as to where I might start >looking? If this is something like a treadmill motor, all you should need is a phase controlled full wave bridge rectifier (2 diodes, 2 SCRs) operated directly from the 120 Vac line. This is how most tread mills do their speed control. The 90V rating on the motor comes from full wave rectifying the incoming 120 Vac but not filtering it; and operating a somewhat less than the full 180 degree conduction for each half-cycle. Most older blueprint machines use similar motors (smaller, of course) and control techniques. For a simple test, just grab a fan-motor rated speed control and connect it to a bridge rectifier feeding the motor. Should work just fine. dwayne -- Dwayne Reid <RemoveMEdwaynerTakeThisOuTspamplanet.eon.net> Trinity Electronics Systems Ltd Edmonton, AB, CANADA (780) 489-3199 voice (780) 487-6397 fax Celebrating 18 years of Engineering Innovation (1984 - 2002) .-. .-. .-. .-. .-. .-. .-. .-. .-. .- `-' `-' `-' `-' `-' `-' `-' `-' `-' Do NOT send unsolicited commercial email to this email address. This message neither grants consent to receive unsolicited commercial email nor is intended to solicit commercial email. -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

Thanks, Dwayne. Not only is this simlpe and inexpensive, but it lets me use some h/w & code from recent projects to modernize the basic idea. I remember fixing bench-top machines that formed axial component leads with this type of driver back in the 70's. It may not be as efficient as PWM driving via FET's, but I can see how it would be clean and simple. For this little laminating machine it should be fine. Now for the catch - current limiting - at AC freq it's always fun getting a good running current averaging circuit with impedance a PIC ADC will handle..... But then again, I did ask for a starting point....... Chris {Quote hidden}> > If this is something like a treadmill motor, all you should > need is a phase > controlled full wave bridge rectifier (2 diodes, 2 SCRs) > operated directly > from the 120 Vac line. This is how most tread mills do their > speed control. > > The 90V rating on the motor comes from full wave rectifying > the incoming > 120 Vac but not filtering it; and operating a somewhat less > than the full > 180 degree conduction for each half-cycle. Most older > blueprint machines > use similar motors (smaller, of course) and control techniques. > > For a simple test, just grab a fan-motor rated speed control > and connect it > to a bridge rectifier feeding the motor. Should work just fine. > > dwayne > > -- > Dwayne Reid <EraseMEdwaynerspamspamBeGoneplanet.eon.net> > Trinity Electronics Systems Ltd Edmonton, AB, CANADA > (780) 489-3199 voice (780) 487-6397 fax > > Celebrating 18 years of Engineering Innovation (1984 - 2002) > .-. .-. .-. .-. .-. .-. .-. .-. .-. .- > `-' `-' `-' `-' `-' `-' `-' `-' `-' > Do NOT send unsolicited commercial email to this email address. > This message neither grants consent to receive unsolicited > commercial email nor is intended to solicit commercial email. > > -- > http://www.piclist.com hint: The PICList is archived three different > ways. See http://www.piclist.com/#archives for details. > > -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.