Re: [Emc-users] Signal generator for induction heating
On Mon, Feb 11, 2013 at 12:45 PM, Gene Heskett ghesk...@wdtv.com wrote: I was just about to say that, but Gene beat me to it. Had an interesting discussion on the Tektronix listserv last week about exactly the same thing. The shorter the ground lead, the better. If you have a ground next to your test points, a short wire wrapped around the grounding section on your probe to the ground works the best - ie, your grounding lead ends up being about 1 or less in length. Tek used to make a grounding lead the snapped onto the end of the probe, and the lead on that was about an inch in length, or maybe less. Mark I have some coil springs that wrap around the probe tip, with a leg that sticks out about the same as the probe tip. PITA to use but they work really well when you need them. Comes with the 200 mhz rated probes from MPJones. Cheers, Gene Those are rather handy. The Tek ones slide over the end, have two little crooks to offset the ground lead. I need to find some more of them in some of my other probe sizes. Mark -- Free Next-Gen Firewall Hardware Offer Buy your Sophos next-gen firewall before the end March 2013 and get the hardware for free! Learn more. http://p.sf.net/sfu/sophos-d2d-feb ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Signal generator for induction heating
On Sun, Feb 10, 2013 at 6:59 PM, Gene Heskett ghesk...@wdtv.com wrote: 1 microsecond can be an eternity to an IGBT. As for your spikes, make sure that the scope is /not/ grounded thru its power cordage, but is grounded locally to your circuit. Even a 6 ground lead can and often will show over voltage spikes where there really aren't any. I was just about to say that, but Gene beat me to it. Had an interesting discussion on the Tektronix listserv last week about exactly the same thing. The shorter the ground lead, the better. If you have a ground next to your test points, a short wire wrapped around the grounding section on your probe to the ground works the best - ie, your grounding lead ends up being about 1 or less in length. Tek used to make a grounding lead the snapped onto the end of the probe, and the lead on that was about an inch in length, or maybe less. Mark -- Free Next-Gen Firewall Hardware Offer Buy your Sophos next-gen firewall before the end March 2013 and get the hardware for free! Learn more. http://p.sf.net/sfu/sophos-d2d-feb ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Signal generator for induction heating
On Monday 11 February 2013 12:41:34 Mark Wendt did opine: On Sun, Feb 10, 2013 at 6:59 PM, Gene Heskett ghesk...@wdtv.com wrote: 1 microsecond can be an eternity to an IGBT. As for your spikes, make sure that the scope is /not/ grounded thru its power cordage, but is grounded locally to your circuit. Even a 6 ground lead can and often will show over voltage spikes where there really aren't any. I was just about to say that, but Gene beat me to it. Had an interesting discussion on the Tektronix listserv last week about exactly the same thing. The shorter the ground lead, the better. If you have a ground next to your test points, a short wire wrapped around the grounding section on your probe to the ground works the best - ie, your grounding lead ends up being about 1 or less in length. Tek used to make a grounding lead the snapped onto the end of the probe, and the lead on that was about an inch in length, or maybe less. Mark I have some coil springs that wrap around the probe tip, with a leg that sticks out about the same as the probe tip. PITA to use but they work really well when you need them. Comes with the 200 mhz rated probes from MPJones. Cheers, Gene -- There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order. -Ed Howdershelt (Author) My web page: http://coyoteden.dyndns-free.com:85/gene is up! My views http://www.armchairpatriot.com/What%20Has%20America%20Become.shtml The hardest thing in the world to understand is the income tax. -- Albert Einstein I was taught to respect my elders, but its getting harder and harder to find any... -- Free Next-Gen Firewall Hardware Offer Buy your Sophos next-gen firewall before the end March 2013 and get the hardware for free! Learn more. http://p.sf.net/sfu/sophos-d2d-feb ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Signal generator for induction heating
Well Indeed it was a scope problem measuring the IGBT drives, since today everything went alright by that side. The problem starts now when I plug the transistor gates. So as I talked whith Gene, I'm going to connect the drives directly to the gates using shielded wire. 2013/2/11 Gene Heskett ghesk...@wdtv.com On Monday 11 February 2013 12:41:34 Mark Wendt did opine: On Sun, Feb 10, 2013 at 6:59 PM, Gene Heskett ghesk...@wdtv.com wrote: 1 microsecond can be an eternity to an IGBT. As for your spikes, make sure that the scope is /not/ grounded thru its power cordage, but is grounded locally to your circuit. Even a 6 ground lead can and often will show over voltage spikes where there really aren't any. I was just about to say that, but Gene beat me to it. Had an interesting discussion on the Tektronix listserv last week about exactly the same thing. The shorter the ground lead, the better. If you have a ground next to your test points, a short wire wrapped around the grounding section on your probe to the ground works the best - ie, your grounding lead ends up being about 1 or less in length. Tek used to make a grounding lead the snapped onto the end of the probe, and the lead on that was about an inch in length, or maybe less. Mark I have some coil springs that wrap around the probe tip, with a leg that sticks out about the same as the probe tip. PITA to use but they work really well when you need them. Comes with the 200 mhz rated probes from MPJones. Cheers, Gene -- There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order. -Ed Howdershelt (Author) My web page: http://coyoteden.dyndns-free.com:85/gene is up! My views http://www.armchairpatriot.com/What%20Has%20America%20Become.shtml The hardest thing in the world to understand is the income tax. -- Albert Einstein I was taught to respect my elders, but its getting harder and harder to find any... -- Free Next-Gen Firewall Hardware Offer Buy your Sophos next-gen firewall before the end March 2013 and get the hardware for free! Learn more. http://p.sf.net/sfu/sophos-d2d-feb ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- *Leonardo Marsaglia*. -- Free Next-Gen Firewall Hardware Offer Buy your Sophos next-gen firewall before the end March 2013 and get the hardware for free! Learn more. http://p.sf.net/sfu/sophos-d2d-feb ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Signal generator for induction heating
Thank you guys for your recomendations. I've been trying and succeded (more or less) using oscillators like the ones from the PC switching power supplies, all of this based on DIY circuits found on the internet. The thing is that, since I'm planning to use LCNC to move the coil along the part, it would be pretty awesome if the system could handle the heater control part too. Anyway, the real deal here is always how to have a clean square signal to fire the igbt's. I'm using dedicated IC's to turn on and of the transistors the one I used is TL494, but the matter is I always have little spikes at the output of the firing IC's, not at the oscillator's output. I couldn't attach a picture of the scope since is too big. Those spikes have a duration of about 1 uS, but I don't know if this is secure and I don't want to blow up the igbt's. In the picture there's only one of the signals, there's the other one 180º phased that has the same problem. Again thanks a lot for your help, I decided to talk here about this because I know there's a lot of people here with way too much knowledge about power electronics, so If you can help me a little I would be very thankful! Leonardo. 2013/2/8 Peter C. Wallace p...@mesanet.com On Fri, 8 Feb 2013, andy pugh wrote: Date: Fri, 8 Feb 2013 09:00:58 +0200 From: andy pugh bodge...@gmail.com Reply-To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net Subject: Re: [Emc-users] Signal generator for induction heating On 8 February 2013 00:29, Sebastian Kuzminsky s...@highlab.com wrote: Maybe a stepgen component in quadrature mode? That would let you easily control the frequency of the output signal. That would be 90 degrees phase-shift I think, so not quite right. siggen might be the way to go. I think there are bridge control chips that handle the dead-time in hardware, and that might be a more reliable approach. I think that the three-phase PWMgen on Mesa cards has complementary signals, with deadband, that might be worth putting an oscilloscope on. -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto This sounds like an ideal application for an Arduino (or cheaper microprocessor) with an _isolated_ serial link to set the parameters. Many little Micros have PWM hardware that will generate non-overlapping push pull drive though it may be harder to find one that can adjust the frequency and duty cycle independently. -- Free Next-Gen Firewall Hardware Offer Buy your Sophos next-gen firewall before the end March 2013 and get the hardware for free! Learn more. http://p.sf.net/sfu/sophos-d2d-feb ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users Peter Wallace Mesa Electronics (\__/) (='.'=) This is Bunny. Copy and paste bunny into your ()_() signature to help him gain world domination. -- Free Next-Gen Firewall Hardware Offer Buy your Sophos next-gen firewall before the end March 2013 and get the hardware for free! Learn more. http://p.sf.net/sfu/sophos-d2d-feb ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- *Leonardo Marsaglia*. -- Free Next-Gen Firewall Hardware Offer Buy your Sophos next-gen firewall before the end March 2013 and get the hardware for free! Learn more. http://p.sf.net/sfu/sophos-d2d-feb ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Signal generator for induction heating
Hello Andy. http://imagebin.org/246204 Here's a picture of what I scoped the other day, this is the signal coming out from the IC's that we use to fire the igbt's, as you can see those spikes are a little dangerous I think. I've talking a lot with Tim and he's a great help, he's always helping me with his advices and knowledge. About using an arduino or fpga, I've been thinking about that too, I need to catch on with VHDL since I've only made some simple counters and multiplexers but I really like the idea of make a whole system from an fpga. Anyway, the main problem here is after the firing IC's since the oscilator is generating a perfect square wave form. 2013/2/10 andy pugh bodge...@gmail.com On 10 February 2013 22:15, Leonardo Marsaglia leonardomarsagli...@gmail.com wrote: based on DIY circuits found on the internet. I guess you have seen: http://webpages.charter.net/dawill/tmoranwms/Elec_IndHeat1.html (Lots of clever stuff, much better done in software now) Anyway, the real deal here is always how to have a clean square signal to fire the igbt's. Sounds like a job for Arduino or FPGA. I can't help feeling that there ought to be a suitable Mesa module, but Arduino's have PWMs that share a clock, so for suitable thresholds are guaranteed not to overlap. I don't know how smoothly you can change frequency -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- Free Next-Gen Firewall Hardware Offer Buy your Sophos next-gen firewall before the end March 2013 and get the hardware for free! Learn more. http://p.sf.net/sfu/sophos-d2d-feb ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- *Leonardo Marsaglia*. -- Free Next-Gen Firewall Hardware Offer Buy your Sophos next-gen firewall before the end March 2013 and get the hardware for free! Learn more. http://p.sf.net/sfu/sophos-d2d-feb ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Signal generator for induction heating
leonardo have you seen this? http://www.fluxeon.com/Roy1200open.html there is a mailing list but I had a client problem and havent been able to resubscribe On Sun, Feb 10, 2013 at 6:00 PM, Leonardo Marsaglia leonardomarsagli...@gmail.com wrote: Hello Andy. -- jeremy youngs -- Free Next-Gen Firewall Hardware Offer Buy your Sophos next-gen firewall before the end March 2013 and get the hardware for free! Learn more. http://p.sf.net/sfu/sophos-d2d-feb ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Signal generator for induction heating
Hello Jeremy, Yes I've been asking some question around there, but lately since I'm using Tim's designs I talked mostly with him via email. I decided to ask here also because I know that there's a lot of people with plenty experience with power electronics, so I think it's a good place. The thing is that, everything from the calculations of the coil and capacitors to the control system is working ok, I'm not sure about feed the transistors because of those spikes, but may be I'll try tomorrow with really low voltage, just to see how it works and if it locks into the resonance frequency. 2013/2/10 jeremy youngs jcyoung...@gmail.com leonardo have you seen this? http://www.fluxeon.com/Roy1200open.html there is a mailing list but I had a client problem and havent been able to resubscribe On Sun, Feb 10, 2013 at 6:00 PM, Leonardo Marsaglia leonardomarsagli...@gmail.com wrote: Hello Andy. -- jeremy youngs -- Free Next-Gen Firewall Hardware Offer Buy your Sophos next-gen firewall before the end March 2013 and get the hardware for free! Learn more. http://p.sf.net/sfu/sophos-d2d-feb ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- *Leonardo Marsaglia*. -- Free Next-Gen Firewall Hardware Offer Buy your Sophos next-gen firewall before the end March 2013 and get the hardware for free! Learn more. http://p.sf.net/sfu/sophos-d2d-feb ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Signal generator for induction heating
On Sunday 10 February 2013 18:52:38 Leonardo Marsaglia did opine: Message additions Copyright Sunday 10 February 2013 by Gene Heskett Thank you guys for your recomendations. I've been trying and succeded (more or less) using oscillators like the ones from the PC switching power supplies, all of this based on DIY circuits found on the internet. The thing is that, since I'm planning to use LCNC to move the coil along the part, it would be pretty awesome if the system could handle the heater control part too. Anyway, the real deal here is always how to have a clean square signal to fire the igbt's. I'm using dedicated IC's to turn on and of the transistors the one I used is TL494, but the matter is I always have little spikes at the output of the firing IC's, not at the oscillator's output. I couldn't attach a picture of the scope since is too big. Those spikes have a duration of about 1 uS, but I don't know if this is secure and I don't want to blow up the igbt's. In the picture there's only one of the signals, there's the other one 180؛ phased that has the same problem. 1 microsecond can be an eternity to an IGBT. As for your spikes, make sure that the scope is /not/ grounded thru its power cordage, but is grounded locally to your circuit. Even a 6 ground lead can and often will show over voltage spikes where there really aren't any. Again thanks a lot for your help, I decided to talk here about this because I know there's a lot of people here with way too much knowledge about power electronics, so If you can help me a little I would be very thankful! Leonardo. 2013/2/8 Peter C. Wallace p...@mesanet.com On Fri, 8 Feb 2013, andy pugh wrote: Date: Fri, 8 Feb 2013 09:00:58 +0200 From: andy pugh bodge...@gmail.com Reply-To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net Subject: Re: [Emc-users] Signal generator for induction heating On 8 February 2013 00:29, Sebastian Kuzminsky s...@highlab.com wrote: Maybe a stepgen component in quadrature mode? That would let you easily control the frequency of the output signal. That would be 90 degrees phase-shift I think, so not quite right. siggen might be the way to go. I think there are bridge control chips that handle the dead-time in hardware, and that might be a more reliable approach. I think that the three-phase PWMgen on Mesa cards has complementary signals, with deadband, that might be worth putting an oscilloscope on. -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto This sounds like an ideal application for an Arduino (or cheaper microprocessor) with an _isolated_ serial link to set the parameters. Many little Micros have PWM hardware that will generate non-overlapping push pull drive though it may be harder to find one that can adjust the frequency and duty cycle independently. Cheers, Gene -- There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order. -Ed Howdershelt (Author) My web page: http://coyoteden.dyndns-free.com:85/gene is up! My views http://www.armchairpatriot.com/What%20Has%20America%20Become.shtml Parkinson's Law: Work expands to fill the time alloted it. I was taught to respect my elders, but its getting harder and harder to find any... -- Free Next-Gen Firewall Hardware Offer Buy your Sophos next-gen firewall before the end March 2013 and get the hardware for free! Learn more. http://p.sf.net/sfu/sophos-d2d-feb ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Signal generator for induction heating
On Sunday 10 February 2013 19:01:08 Leonardo Marsaglia did opine: Message additions Copyright Sunday 10 February 2013 by Gene Heskett Hello Andy. http://imagebin.org/246204 Here's a picture of what I scoped the other day, this is the signal coming out from the IC's that we use to fire the igbt's, as you can see those spikes are a little dangerous I think. First, I am a CET, and a retired (mostly) broadcast engineer. 2nd, Correct, both the spikes, and all that racket on the falling edge bothers me, a lot. First on the overvolt spikes, I'd make sure the scope ground is floating so that you can attach it to the circuits common. They may not be near as pronounced if a ground loop is eliminated. 2nd, that double or triple shuffle on the falling edge isn't at all good. Its needless switching and heating in the transistors./ Perhaps the grounding and supply bypassing are both suspect. I'd check to see what effect a .1 paper/mylar capacitor across the buses might indicate poor bypassing. Do you have a URL to that circuit? I'll take a look at it if I can. I've talking a lot with Tim and he's a great help, he's always helping me with his advices and knowledge. About using an arduino or fpga, I've been thinking about that too, I need to catch on with VHDL since I've only made some simple counters and multiplexers but I really like the idea of make a whole system from an fpga. Anyway, the main problem here is after the firing IC's since the oscilator is generating a perfect square wave form. 2013/2/10 andy pugh bodge...@gmail.com On 10 February 2013 22:15, Leonardo Marsaglia leonardomarsagli...@gmail.com wrote: based on DIY circuits found on the internet. I guess you have seen: http://webpages.charter.net/dawill/tmoranwms/Elec_IndHeat1.html (Lots of clever stuff, much better done in software now) Anyway, the real deal here is always how to have a clean square signal to fire the igbt's. Sounds like a job for Arduino or FPGA. I can't help feeling that there ought to be a suitable Mesa module, but Arduino's have PWMs that share a clock, so for suitable thresholds are guaranteed not to overlap. I don't know how smoothly you can change frequency -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- Free Next-Gen Firewall Hardware Offer Buy your Sophos next-gen firewall before the end March 2013 and get the hardware for free! Learn more. http://p.sf.net/sfu/sophos-d2d-feb ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users Cheers, Gene -- There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order. -Ed Howdershelt (Author) My web page: http://coyoteden.dyndns-free.com:85/gene is up! My views http://www.armchairpatriot.com/What%20Has%20America%20Become.shtml It matters not whether you win or lose; what matters is whether II win or lose. -- Darrin Weinberg I was taught to respect my elders, but its getting harder and harder to find any... -- Free Next-Gen Firewall Hardware Offer Buy your Sophos next-gen firewall before the end March 2013 and get the hardware for free! Learn more. http://p.sf.net/sfu/sophos-d2d-feb ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Signal generator for induction heating
Hello Gene, and thanks for your answer.
I have the circuit in PDF format, would you like me to send it to you so
you can see it?
2013/2/10 Gene Heskett ghesk...@wdtv.com
On Sunday 10 February 2013 19:01:08 Leonardo Marsaglia did opine:
Message additions Copyright Sunday 10 February 2013 by Gene Heskett
Hello Andy.
http://imagebin.org/246204
Here's a picture of what I scoped the other day, this is the signal
coming out from the IC's that we use to fire the igbt's, as you can see
those spikes are a little dangerous I think.
First, I am a CET, and a retired (mostly) broadcast engineer.
2nd, Correct, both the spikes, and all that racket on the falling edge
bothers me, a lot.
First on the overvolt spikes, I'd make sure the scope ground is floating so
that you can attach it to the circuits common. They may not be near as
pronounced if a ground loop is eliminated.
2nd, that double or triple shuffle on the falling edge isn't at all good.
Its needless switching and heating in the transistors./
Perhaps the grounding and supply bypassing are both suspect. I'd check to
see what effect a .1 paper/mylar capacitor across the buses might indicate
poor bypassing.
Do you have a URL to that circuit? I'll take a look at it if I can.
I've talking a lot with Tim and he's a great help, he's always helping
me with his advices and knowledge.
About using an arduino or fpga, I've been thinking about that too, I
need to catch on with VHDL since I've only made some simple counters
and multiplexers but I really like the idea of make a whole system from
an fpga.
Anyway, the main problem here is after the firing IC's since the
oscilator is generating a perfect square wave form.
2013/2/10 andy pugh bodge...@gmail.com
On 10 February 2013 22:15, Leonardo Marsaglia
leonardomarsagli...@gmail.com wrote:
based on DIY circuits found on the internet.
I guess you have seen:
http://webpages.charter.net/dawill/tmoranwms/Elec_IndHeat1.html
(Lots of clever stuff, much better done in software now)
Anyway, the real deal here is always how to have a clean square
signal to fire the igbt's.
Sounds like a job for Arduino or FPGA. I can't help feeling that there
ought to be a suitable Mesa module, but Arduino's have PWMs that share
a clock, so for suitable thresholds are guaranteed not to overlap. I
don't know how smoothly you can change frequency
--
atp
If you can't fix it, you don't own it.
http://www.ifixit.com/Manifesto
--
Free Next-Gen Firewall Hardware Offer
Buy your Sophos next-gen firewall before the end March 2013
and get the hardware for free! Learn more.
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Cheers, Gene
--
There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order.
-Ed Howdershelt (Author)
My web page: http://coyoteden.dyndns-free.com:85/gene is up!
My views
http://www.armchairpatriot.com/What%20Has%20America%20Become.shtml
It matters not whether you win or lose; what matters is whether I I win or
lose.
-- Darrin Weinberg
I was taught to respect my elders, but its getting
harder and harder to find any...
--
Free Next-Gen Firewall Hardware Offer
Buy your Sophos next-gen firewall before the end March 2013
and get the hardware for free! Learn more.
http://p.sf.net/sfu/sophos-d2d-feb
___
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https://lists.sourceforge.net/lists/listinfo/emc-users
--
*Leonardo Marsaglia*.
--
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Buy your Sophos next-gen firewall before the end March 2013
and get the hardware for free! Learn more.
http://p.sf.net/sfu/sophos-d2d-feb
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Re: [Emc-users] Signal generator for induction heating
On Sunday 10 February 2013 20:58:28 Leonardo Marsaglia did opine: Hello Gene, and thanks for your answer. I have the circuit in PDF format, would you like me to send it to you so you can see it? Yes, please, PM because the server will strip attachments. Cheers, Gene -- There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order. -Ed Howdershelt (Author) My web page: http://coyoteden.dyndns-free.com:85/gene is up! My views http://www.armchairpatriot.com/What%20Has%20America%20Become.shtml Be open to other people -- they may enrich your dream. I was taught to respect my elders, but its getting harder and harder to find any... -- Free Next-Gen Firewall Hardware Offer Buy your Sophos next-gen firewall before the end March 2013 and get the hardware for free! Learn more. http://p.sf.net/sfu/sophos-d2d-feb ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Signal generator for induction heating
-BEGIN PGP SIGNED MESSAGE- Hash: SHA1 Post it online somewhere if you can and I'll review it as well. - From your scope image, I'd say it looks like you may have some grounding issues with your 'scope probe (as Gene mentioned, use a direct ground from the probe tip to a ground local to the signal you're probing...ideally within a cm or so), in addition to possible other problems. The over-shoot and under-shoot (ringing) are likely caused either by your scope probing techniques, by the signal transition speed, or possibly both. If better probe grounding still shows the ringing, you should try fix it...a couple possible options are: * Slow down the turn-on and turn-off transition times of your power devices, reducing di/dt. Note that this increases the time spent in the linear region, increasing power dissipation. * Add or improve the protection devices clamping over- and under-shoot, typically something like a high speed TVS zener diode. As for the second 'runt' pulse you're seeing, I suspect this is caused by your drive circuit...my first guesses would be magnetic feedback from the switched current or ground transients between the driver logic and the IGBT power devices, but without a circuit diagram and maybe a picture of the installed wiring, I'm just guessing. On 2/10/2013 7:40 PM, Leonardo Marsaglia wrote: Hello Gene, and thanks for your answer. I have the circuit in PDF format, would you like me to send it to you so you can see it? 2013/2/10 Gene Heskett ghesk...@wdtv.com On Sunday 10 February 2013 19:01:08 Leonardo Marsaglia did opine: Message additions Copyright Sunday 10 February 2013 by Gene Heskett Hello Andy. http://imagebin.org/246204 Here's a picture of what I scoped the other day, this is the signal coming out from the IC's that we use to fire the igbt's, as you can see those spikes are a little dangerous I think. First, I am a CET, and a retired (mostly) broadcast engineer. 2nd, Correct, both the spikes, and all that racket on the falling edge bothers me, a lot. First on the overvolt spikes, I'd make sure the scope ground is floating so that you can attach it to the circuits common. They may not be near as pronounced if a ground loop is eliminated. 2nd, that double or triple shuffle on the falling edge isn't at all good. Its needless switching and heating in the transistors./ Perhaps the grounding and supply bypassing are both suspect. I'd check to see what effect a .1 paper/mylar capacitor across the buses might indicate poor bypassing. Do you have a URL to that circuit? I'll take a look at it if I can. I've talking a lot with Tim and he's a great help, he's always helping me with his advices and knowledge. About using an arduino or fpga, I've been thinking about that too, I need to catch on with VHDL since I've only made some simple counters and multiplexers but I really like the idea of make a whole system from an fpga. Anyway, the main problem here is after the firing IC's since the oscilator is generating a perfect square wave form. 2013/2/10 andy pugh bodge...@gmail.com On 10 February 2013 22:15, Leonardo Marsaglia leonardomarsagli...@gmail.com wrote: based on DIY circuits found on the internet. I guess you have seen: http://webpages.charter.net/dawill/tmoranwms/Elec_IndHeat1.html (Lots of clever stuff, much better done in software now) Anyway, the real deal here is always how to have a clean square signal to fire the igbt's. Sounds like a job for Arduino or FPGA. I can't help feeling that there ought to be a suitable Mesa module, but Arduino's have PWMs that share a clock, so for suitable thresholds are guaranteed not to overlap. I don't know how smoothly you can change frequency -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- - Free Next-Gen Firewall Hardware Offer Buy your Sophos next-gen firewall before the end March 2013 and get the hardware for free! Learn more. http://p.sf.net/sfu/sophos-d2d-feb ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users Cheers, Gene -- There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order. -Ed Howdershelt (Author) My web page: http://coyoteden.dyndns-free.com:85/gene is up! My views http://www.armchairpatriot.com/What%20Has%20America%20Become.shtml It matters not whether you win or lose; what matters is whether I I win or lose. -- Darrin Weinberg I was taught to respect my elders, but its getting harder and harder to find any... -- Free Next-Gen Firewall Hardware Offer Buy your Sophos next-gen firewall before the end March 2013 and get the hardware
Re: [Emc-users] Signal generator for induction heating
Leonardo, if possible, I, too, would like to have the circuit diagram. I have done some experimenting on melting aluminum and brass with a copper coil driven by a 1800 W usual household induction heating plate circuit. Problem one is to bypass the security precautions, problem two is that the inductivity of my coil is much lower than the normal heating coils, so in order to keep the frequency of about 50 kHz I have to use much larger capacitors. This seems to change the complex resistance of the resonance circuit in a way to reduce effectivity. I want to get off the induction plate electronics. Thank you Peter Am 11.02.2013 02:40, schrieb Leonardo Marsaglia: Hello Gene, and thanks for your answer. I have the circuit in PDF format, would you like me to send it to you so you can see it? 2013/2/10 Gene Heskett ghesk...@wdtv.com On Sunday 10 February 2013 19:01:08 Leonardo Marsaglia did opine: Message additions Copyright Sunday 10 February 2013 by Gene Heskett Hello Andy. http://imagebin.org/246204 Here's a picture of what I scoped the other day, this is the signal coming out from the IC's that we use to fire the igbt's, as you can see those spikes are a little dangerous I think. First, I am a CET, and a retired (mostly) broadcast engineer. 2nd, Correct, both the spikes, and all that racket on the falling edge bothers me, a lot. First on the overvolt spikes, I'd make sure the scope ground is floating so that you can attach it to the circuits common. They may not be near as pronounced if a ground loop is eliminated. 2nd, that double or triple shuffle on the falling edge isn't at all good. Its needless switching and heating in the transistors./ Perhaps the grounding and supply bypassing are both suspect. I'd check to see what effect a .1 paper/mylar capacitor across the buses might indicate poor bypassing. Do you have a URL to that circuit? I'll take a look at it if I can. I've talking a lot with Tim and he's a great help, he's always helping me with his advices and knowledge. About using an arduino or fpga, I've been thinking about that too, I need to catch on with VHDL since I've only made some simple counters and multiplexers but I really like the idea of make a whole system from an fpga. Anyway, the main problem here is after the firing IC's since the oscilator is generating a perfect square wave form. 2013/2/10 andy pugh bodge...@gmail.com On 10 February 2013 22:15, Leonardo Marsaglia leonardomarsagli...@gmail.com wrote: based on DIY circuits found on the internet. I guess you have seen: http://webpages.charter.net/dawill/tmoranwms/Elec_IndHeat1.html (Lots of clever stuff, much better done in software now) Anyway, the real deal here is always how to have a clean square signal to fire the igbt's. Sounds like a job for Arduino or FPGA. I can't help feeling that there ought to be a suitable Mesa module, but Arduino's have PWMs that share a clock, so for suitable thresholds are guaranteed not to overlap. I don't know how smoothly you can change frequency -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- Free Next-Gen Firewall Hardware Offer Buy your Sophos next-gen firewall before the end March 2013 and get the hardware for free! Learn more. http://p.sf.net/sfu/sophos-d2d-feb ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users Cheers, Gene -- There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order. -Ed Howdershelt (Author) My web page: http://coyoteden.dyndns-free.com:85/gene is up! My views http://www.armchairpatriot.com/What%20Has%20America%20Become.shtml It matters not whether you win or lose; what matters is whether I I win or lose. -- Darrin Weinberg I was taught to respect my elders, but its getting harder and harder to find any... -- Free Next-Gen Firewall Hardware Offer Buy your Sophos next-gen firewall before the end March 2013 and get the hardware for free! Learn more. http://p.sf.net/sfu/sophos-d2d-feb ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users -- Free Next-Gen Firewall Hardware Offer Buy your Sophos next-gen firewall before the end March 2013 and get the hardware for free! Learn more. http://p.sf.net/sfu/sophos-d2d-feb ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Signal generator for induction heating
On Fri, 8 Feb 2013, andy pugh wrote: Date: Fri, 8 Feb 2013 09:00:58 +0200 From: andy pugh bodge...@gmail.com Reply-To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net Subject: Re: [Emc-users] Signal generator for induction heating On 8 February 2013 00:29, Sebastian Kuzminsky s...@highlab.com wrote: Maybe a stepgen component in quadrature mode? That would let you easily control the frequency of the output signal. That would be 90 degrees phase-shift I think, so not quite right. siggen might be the way to go. I think there are bridge control chips that handle the dead-time in hardware, and that might be a more reliable approach. I think that the three-phase PWMgen on Mesa cards has complementary signals, with deadband, that might be worth putting an oscilloscope on. -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto This sounds like an ideal application for an Arduino (or cheaper microprocessor) with an _isolated_ serial link to set the parameters. Many little Micros have PWM hardware that will generate non-overlapping push pull drive though it may be harder to find one that can adjust the frequency and duty cycle independently. -- Free Next-Gen Firewall Hardware Offer Buy your Sophos next-gen firewall before the end March 2013 and get the hardware for free! Learn more. http://p.sf.net/sfu/sophos-d2d-feb ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users Peter Wallace Mesa Electronics (\__/) (='.'=) This is Bunny. Copy and paste bunny into your ()_() signature to help him gain world domination. -- Free Next-Gen Firewall Hardware Offer Buy your Sophos next-gen firewall before the end March 2013 and get the hardware for free! Learn more. http://p.sf.net/sfu/sophos-d2d-feb ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Signal generator for induction heating
I retrofit an induction heat treat machines that operates in exactly the same manner. The machine I worked on was made by Inductoheat. I replaced the motion controller with a PC running Mach3 ( this was years ago.. before I saw the light.. ;-) ) I tied into the existing heater controls. Be careful how you run your wires. The induction heating circuits thrown off intense magnetic fields. Dave On 2/7/2013 5:04 PM, Leonardo Marsaglia wrote: Hello everybody. This may be a weird question but I think with a little help of you this could be very doable with EMC. Turns out that I'm making tests with induction heating to set up a machine that will use a ballscrew to position a coil wich will heat a part between centers. Anyway, the idea was always to use LinuxCNC to control de position of the coil, and activate the power to heat, then the timer, and then turn on the shower to cool the part, and so on. I was thinking and this is the hardest part. Would it be possible to control the induction heater using signals coming from and to LinuxCNC?. The basic thing that I need is a Square wave generator, that outputs 2 signals one at 180º from the other, and with a duty cycle less than 50%. This is to avoid complications with the switching transistors. I'm almost sure that hal could do this, even read the signals to adjust the frequency. The only thing I'm not sure about is if I could use components like SIGGEN, because for example this one does not allow me to change the duty cycle, and if I use PWMGEN I can change the frequency at any time but only when I load the component. May be I will need to make a custom component, but that's not a problem. What do you think guys? Thanks in advance as always. -- Free Next-Gen Firewall Hardware Offer Buy your Sophos next-gen firewall before the end March 2013 and get the hardware for free! Learn more. http://p.sf.net/sfu/sophos-d2d-feb ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Signal generator for induction heating
On 07.02.13 19:04, Leonardo Marsaglia wrote: The basic thing that I need is a Square wave generator, that outputs 2 signals one at 180º from the other, and with a duty cycle less than 50%. This is to avoid complications with the switching transistors. I'm almost sure that hal could do this, even read the signals to adjust the frequency. If a frequency of twice the desired output rate is used to clock a JK flip-flop, the result is two antiphase 50% MS ratio clocks, from Q and Q' respectively. The less than 50% duty cycle that you refer to is called dead time, and typically ensures that totem-pole connected power devices do not conduct at the same time, shorting out the power supply. While that can be added by simple diode/resistor networks when driving power MOSFETs, it is already included in many gate drive chips, such as the IR2111, which provides a deadtime of 650 ns, typical. (Others are adjustable, IIRC.) All that would be required then, is a 2x clock from LinuxCNC, or just a DC enable, if a gated oscillator were simply turned on and off by LinuxCNC. That would be much more robust than generating the antiphase clocks in software, where a software hiccup could lose the deadtime, destroying the power devices, or melting other gear. (Just my $0.02. :) It sounds like a very interesting project, and a lot of fun, but susceptible to the wrong things glowing red hot. Erik -- A good scare is worth more than good advice.(Proverb) -- Free Next-Gen Firewall Hardware Offer Buy your Sophos next-gen firewall before the end March 2013 and get the hardware for free! Learn more. http://p.sf.net/sfu/sophos-d2d-feb ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Signal generator for induction heating
On 2/7/2013 10:39 PM, Erik Christiansen wrote: On 07.02.13 19:04, Leonardo Marsaglia wrote: The basic thing that I need is a Square wave generator, that outputs 2 signals one at 180º from the other, and with a duty cycle less than 50%. This is to avoid complications with the switching transistors. I'm almost sure that hal could do this, even read the signals to adjust the frequency. If a frequency of twice the desired output rate is used to clock a JK flip-flop, the result is two antiphase 50% MS ratio clocks, from Q and Q' respectively. The less than 50% duty cycle that you refer to is called dead time, and typically ensures that totem-pole connected power devices do not conduct at the same time, shorting out the power supply. While that can be added by simple diode/resistor networks when driving power MOSFETs, it is already included in many gate drive chips, such as the IR2111, which provides a deadtime of 650 ns, typical. (Others are adjustable, IIRC.) All that would be required then, is a 2x clock from LinuxCNC, or just a DC enable, if a gated oscillator were simply turned on and off by LinuxCNC. That would be much more robust than generating the antiphase clocks in software, where a software hiccup could lose the deadtime, destroying the power devices, or melting other gear. (Just my $0.02. :) It sounds like a very interesting project, and a lot of fun, but susceptible to the wrong things glowing red hot. Erik You guys are braver than me. I did some service on the machine I retrofit later when they blew a scr in the power cabinet. I swapped out the entire rectifier/scr stack with identical parts from another machine. The semi conductor devices were about the size of hockey pucks and there was a stack of them probably 16 tall with several interconnections to buss bars and trigger circuits. I got the machine running again for a while, but then something else failed and they called in Inductoheat to find the cause of the problem. I was fine with that. That machine has a walk in power cabinet with a large 480 volt disconnect switch (I think it was 400 amp) that feeds the cabinet. The machine has its own cooler on the plant roof to keep the power circuits and the liquid quench tank cool. (Many of the buss bars are hollow and coolant flows through them to keep them from melting)The machine brings a 1.25 diameter steel bar from room temp to red hot in a couple of seconds. Yep, better be sure that power control is correct or else you might have a lot of melted copper in the bottom of the power cabinet! Dave -- Free Next-Gen Firewall Hardware Offer Buy your Sophos next-gen firewall before the end March 2013 and get the hardware for free! Learn more. http://p.sf.net/sfu/sophos-d2d-feb ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
Re: [Emc-users] Signal generator for induction heating
On 8 February 2013 00:29, Sebastian Kuzminsky s...@highlab.com wrote: Maybe a stepgen component in quadrature mode? That would let you easily control the frequency of the output signal. That would be 90 degrees phase-shift I think, so not quite right. siggen might be the way to go. I think there are bridge control chips that handle the dead-time in hardware, and that might be a more reliable approach. I think that the three-phase PWMgen on Mesa cards has complementary signals, with deadband, that might be worth putting an oscilloscope on. -- atp If you can't fix it, you don't own it. http://www.ifixit.com/Manifesto -- Free Next-Gen Firewall Hardware Offer Buy your Sophos next-gen firewall before the end March 2013 and get the hardware for free! Learn more. http://p.sf.net/sfu/sophos-d2d-feb ___ Emc-users mailing list Emc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/emc-users
