8i20 DC power supply companion board.
20 Jan 2020 15:39 #155262
by andypugh
Yes, on my mill the PSU drives 3 x 8i20 + 1 x STMBL.
Incidentally, I have the inrush current limiter resistor and the bypass on the AC side of the rectifier, IIRC. That lets me use a zero-switching device which helps a little with the inrush too (also I think that AC switching SSRs are a bit cheaper)
Replied by andypugh on topic 8i20 DC power supply companion board.
[As I look into this I start to realize what the idea of the 8i20 probably was. If you have multiple motors/8i20's in a single system, you might throw together a large single DC bus supply. Control the input with a contactor and do exactly as you have done, using one of the 8i20's bus voltage pins to control the inrush bypass through hal
Yes, on my mill the PSU drives 3 x 8i20 + 1 x STMBL.
Incidentally, I have the inrush current limiter resistor and the bypass on the AC side of the rectifier, IIRC. That lets me use a zero-switching device which helps a little with the inrush too (also I think that AC switching SSRs are a bit cheaper)
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20 Jan 2020 18:31 #155268
by blazini36
Replied by blazini36 on topic 8i20 DC power supply companion board.
DC SSR's are not very common or cheap at 400v. I have the inrush limiter on the DC side because the current thought is to use an IGBT which only works on DC. I have traics on the AC side for enabling the input voltage (AC SSRs probably are triacs with drivers in a case).
The thing about discrete components is an IGBT and triac is like $1 each.
The thing about discrete components is an IGBT and triac is like $1 each.
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26 Jan 2020 15:42 #155810
by blazini36
Replied by blazini36 on topic 8i20 DC power supply companion board.
Ran the idea through a thread on an electronics forum and I'm getting hammered by power factor correction nazis. Apparently it's not correct or proper just to throw some caps and a rectifier in a box and call it a DC power supply. PFC ics do provide a means to limit inrush so I might go down that rabbit hole but that's gonna take me a bit to figure out.
On a side note I'm starting to miss my 8i20. I'm using (or trying to use) a DMM servo drive just to realize it uses sinking I/O where the 7i76e I use obviously only has sourcing I/O so now I'm working on figuring out mb2hal to control it over rs232.
On a side note I'm starting to miss my 8i20. I'm using (or trying to use) a DMM servo drive just to realize it uses sinking I/O where the 7i76e I use obviously only has sourcing I/O so now I'm working on figuring out mb2hal to control it over rs232.
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28 Jan 2020 20:36 #156045
by andypugh
Replied by andypugh on topic 8i20 DC power supply companion board.
At your likely duty cycle and power rating, I would suggest ignoring them.
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13 Feb 2020 01:47 #157244
by blazini36
Replied by blazini36 on topic 8i20 DC power supply companion board.
Well like I said the PFC IC's handle inrush as a built in function so its the best bet rather than trying to design some bypass circuit.
I do find them a bit complicated though so it'll take a bit before I can get enough time to make a dent in this, but it's definitely something I'll get back to.
I do find them a bit complicated though so it'll take a bit before I can get enough time to make a dent in this, but it's definitely something I'll get back to.
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