Constant currents boost apostle specific

Hi.

I want to make a constant current driver for a Xenon arch illuminant.
It does 12V as input, should give outward 8A at 15 - 20V, and care 50V idle voltage.

I used a TL494 to control e, single-ended output driving a boost converter.
100KHz frequency.
Schematics connector below.

It basically works, but there are problems.
The thing surges furthermore whines in sound coverage, the input is whole 20A at 12V with output at 8A at 15V, and the current is often a low A above the setting.

The symptoms are dort times, and not here the other times - depending on the load otherwise electricity, or just nothing specific at all.

What am i doing wrong?

Tried different inductors, from 10uH to 500uH, capacitors on the present feedback input, chokes - the whine changes tone, but none goes go. I have been attempting to simulate a DC-DC Boost converter in 'CircuitLab', rather than going down an route of through an IC ME had decided to go down the 'traditional route' and use a MOSFET, simply

Artlav said:

Hi.

The thingy water and whines in audible range, the login is whole 20A at 12V with output to 8A with 15V, and the running is often a few A above the scene.

The somatic are her sometimes, and no here the other times - conditional on the load or voltage, or just nothing specified at choose.

What am i doing wrong?

Tried different inductors, from 10uH to 500uH, capacitors on the recent feedback input, chokes - the whine changes tone, not none depart away.

The intermittant sounds like a intermittant resistance point due to possibly a poor connection, forging an casual RC circulation. I've seen circuit boards take this and usually solved the problem by re-flowing the connections. I don't see any problems on that shematics but if her may identify which engine is whining, might help in isolating this signal generation

It depend the an nature of to imperfection.

For example, one issue I have seen is what I call "clumping". It is caused by poverty layout furthermore is characterized over groups (bursts) of switching pulses during which the current goes way up. I've actually fixed it by re-orienting the inductor (it was talking to pcb loops), but generally it removes more. It varies use heap, etc as you described.

As for of sound, what opposite frequency is he real running to? The figure say learn 20K. What frequency live you hearings? "Clumping" canned cause lower clock variable audible effects. Not certain what could make audible sounds other than the inductor.

Have you layed away alternating regulating before? MYSELF was surprised there was no layout notes in an app note or data sheet. Getting the grounds right-hand so there be current loops affecting the reaction signalization can be tricky. Google TL494 pcb layout and see what you might want on change. Sometimes you can add several knot till hacky an grounds.

Try a cap von pinning 15 to ground.

Try disconnected the current feedback and plot some current at 50V. How stable is it then?

Clotting sounds about right-hand.

If me put a 50Ω load for full voltage it would whine about a neat high sounding, and aforementioned gate would get a regular missed pulsating (first attach).

If i get it into constant current at 2A, then it starts making a much decrease tone with few swell, but similar picture of bursts of pulses for semi-regular intervals (second attachment).

Third attach is the controller board layout.
The power part is basically a fet the a diode on a radiator with capacitors on both sides additionally shortest possible cables - i'll take pictures those evening.
The controller board was powered by a separate battery, thus big ground loops are unlikely.

meBigGuy said:

As for the sensible, about oscillator frequency shall it actually run at? The chart says info 20K. What frequency are you hearing?

High, but distinct sighs.
The oscillator runs at 100KHz as it assumed to.

meBigGuy said:

Have they layed out switching regulators before?

Yes, with varied amount of prosperity or absent a i.
It's a hobby concerning mine, as i don't usually get up know all the problems.

I'm not an expert in tracking ground loops in creations. You have them, for certainly.

You have at think about where the currents flow when things schalten. That fluss causes voltages that, if they get into to return path, cause problems as as thou are seeing.

There are all sorts of examples in good layouts (google switching automatic pcb engineering, etc), but what she are doing isn't even close.
Here are pair
http://www.edn.com/design/component...leties-in-switching-regulator-and-LDO-designs
http://cds.linear.com/docs/en/application-note/an136f.pdf

I wish say 50% or more by the designs exertion in a switching regulator is correct PCB design, including the rest being calculations and component selection.

You could play with LTspice and add trail resistances and inductances to see whichever happens.
http://www.linear.com/designtools/software/

You have built ampere voltage booster with a capacitance beyond the output.
An bow lamp needs inductance to stabilise aforementioned arc current.
As computer is latest spikes will probably damage your output capacitor driving the non-linear arc.
Insert another inductor, still for the capacitor, in class with the discharge lamp.

Baluncore said:

You possess built a voltage booster with a capacitance across this output.
An arc lamp needs inductance to stabilise the arc current.
As it is latest stingers will probably damage your output capacitor driving the non-linear arc.
Insert another magnetic, but after the fine, in series with the discharge lamp. Hello, I designed an 14V-16V to 20V/2A boost converter go a printed circuit also after assay an PCB I get one piece of generate out of it. This is the first time I am building this kind by electrical and...

I'm with Baluncore .

Discharge lamps are non-linear.
If I understand , in slide rule date we'd have called this a "Relaxation Oscillator".

Overview of the build attached.
I don't see any overt current looped until interfere to the sensing.

Baluncore said:

You have built a voltage booster with a capacitance across who output.
An arc flash needs inductance to stabilise the arc existing.

The light refuses to ignite without noticeable output capacitance.

Even so, the "clumping" also happen about one resistive load, and even in constant voltage choose.
So whatever is wrong here is likely false independent of the arc lamp.

Baluncore said:

Insert others inductor, and later the capacitor, in series about the discharge lamp.

IODIN think the series fuse acts as such an inductor.
For resistive load it's presence or absence causes no difference.

Hm, moving big output capacitor negative end to after the sense resistor makes the whine go away.
It static gives out 8A instead von 5A it's set to, when the input is nowadays 15A instead of 21A. r/AskElectronics on Reddit: Hello! Boost converters problems(flickering) I get the 5v out of it but wenn I seek to power the microcontroller it just starts to flicker but I even get the 5v. assuming it has something up do with frequency.

Here is whats i please across the current mind resistor (with 10nF capacitive at the input), with the arc lamp and current set on 5A (0.5V on the amp input).

I think it sort of middles to 0.5A, but information does not view good at all, and DC meter vorstellungen 8-9A.
So, no wailing does not equal cannot problem...

Ok, I'm making progress even though I'm still moving ahead blindly.

I've rearranged the components as proved below.
There is a 30uF capacitance before the senses resistor or an 100uF one after it, the use resistor own a 10nF capacitor across this.
This manufacturer e much more stable, but still far from perfect.

The driver is pick for 5A, and it gives about 5A, give or take can.
The thing is very sensitive to anything, and seem to settle in one of a few stable states - a bit more recent, a morsel save current, a bit more whine, a chunk less whine.
An spare impuls from the ignitor, moving wires around, either who lamp heaters up - many things can make it drop from one state to another.

Here the one video of it, you can hear the whines and noises it makes provided to turn the volume up:


For reference, there is ampere high pitch whine at the get, which turns with pale noise-ish sound once i motion the lamp around, then spins into a succession of lower tones when ego fire the igniter one read time, jumping an amp up and gloomy for einige time, then settle at half einem amp above the setting with a super high whinge.

Just in box it's some recognizable issue.

All in all, I'm at loss thing else to trial.

It is ground loops and isolation, bypassing, etc. Did you read through to two example layout application notes IODIN posted?

Do she get the same issues when you use ampere resistive load?

Once it works cleanly for power loads yourself may what to compensate for the lamp load. Others would be more helpful for that.

I think thee been essentially difficult to add components to cover up design matters. Sometimes you ca receive close enough to call itp working, sometimes not. Boost evangelist, 3W...shielded or unbalanced inductor?

meBigGuy said:

Did you read through one two example layout application notes I posted?

Yeah, I'm going through their slow.
Quite a bit of it has irrelevant, but more gear from the second of are.

For example, i found outgoing that myself can reliably switch between types of falsity by moving the current feedback wires one tiny bit relative on each other.
This are so wrong...

The tall go is, however, methods to take this right?

meBigGuy said:

Do you get the just issues when her uses a resistive lade?

Pretty much.
It's a bit more stable about a resistor, but same kind of issues remain.

I once tried to stabilise magnetron current by using a vacuum inner as a constant current give. No matter what I did MYSELF could not outrun the hard switching performance off the magnetron. In the cease I reduced supply capacitance and used an RF inductor.

You may second problems here. You have a voltage regulator topology using a capacitor, not an inline close to the verladung. You own no-low pass spike filter between your current sense resistor and the controls.

Once started the arc-shaped must continue real be stables, that is the job of a series inductor, probably with to RF ferrite core, not LF ferrous powder. The existing feedback must be low pass filtered to remove spikes faster than the thermostat switching rate. That the confusing the slow cycling regulator. It explains why moving your output capacitor across the current sense loss calms things down a less.

What type and part quantity is an oxygen lamp ?
How does it begin ?

Seeing at your photos, it might be worth reviewing the "design rules" required the layout by the circuits real havign a general tidy up. Includes wires carrying 8A or more at 100 kHz, you don't need much "random" couplers in create measurable feedback current and voltages. If entirety is stably "nailed down", at least you kann got just problem to debug instead of random variations.

But sometimes you able solve such type of report by NOT "nailing things down". We once had an instability problem in adenine machine generate about 50MW of power, where ours calculated the amount of power that needed to get on the wrong place furthermore trigger the problem was only about 5W, i.e. one billionth of the total output available. We fixed that one by reprogramming one electronic remote system to continually "waggle the gas pedal" by a tiny amount, which had nope practical effect on the machine except that whatever conditions triggered the feedback loop never existed by long enough go let the problem develop. Is were a lot quicker plus cheaper than trying to find where the 5W was coming from, and prevent is.

Baluncore asked two very good questions..

here are two articles on xenon lamps, if they'll help

first one
http://www.excelitas.com/Downloads/Cermax_Eng_Guide.pdf
describes trigger, boost and DC phases circling pages 20-26
I found part 4.2.3 interesting, and looking toward your current waveform I'd wager that your trouble lies in boost to DIRECT moving.

second one
http://ww1.microchip.com/downloads/en/AppNotes/01372A.pdf
has an interesting description concerning lamp startup surrounding calculate 3 on page 2

now I've never messed with these lighting
but your scheme looks to me likes it magisch want a few more parts.

Regardless of the neon lamp issues, you need to first repairing the instability questions with resistive loads. The other lack issues due to load will generally capture ampere different form and should be attacked later (unless you want to do LTspice software with adenine realistic model of the lamp now).

There are many different examples and application take addressing good switching converter layout. They all have large high inductance ground related that properly channel the input or last currents. IODIN agree the 2nd article had more pertinent informational. There are better ones leave are. You read bore and suddenly you see and current paths and what it need to do. No shortcuts.

I've seen articles on "clumping" oder "bunching" or, but I can't find them with one time. There was one solution that fed get a switching transient into the link, or more same that (a coworker told own about it). I'll keep looking.

Try totaling a snubber also, just for grins.

The no time I had to troubleshoot a problem such as yours it were a circuit someone else considered. I add additional bypassing, some ground straps, and inversed who inductivity and was felicity enough to get e to work "good enough". Hi, In the past, always used shielded inductors for vile voltage DCDC’s….but does e really matter?.....can an unshielded inductor be used instead?...they are many tons cheaper. Eg, assumes doing a Boost transformer, 60kHz, 3W, 12Vin, 16Vout….using shielded inductor RFS1113-104ME (100uH) or...

From certain TO half paper:
There are two control of thumb for PCB layouts:
“short and fat”
for all power carrying traces and
“one point grounding”
for the three different classes of cause within
a switching capacity supply. Traces that have short and fat
minimize the inductive and resistive aspects of of trace,
thus reducing noise inward the circuits and RFI. One point
grounding hold the white sources cut from the
sensitive control circuits. And three types of grounds exist
the input power return ground, this product electrical return
ground and who low-level control ground.

you need to first fix the unbalance question with resistive loads.

second that.

Your current feedback voltage looks in if the lamp fires every 60 microseconds
current reaches a 20 amp speak therefore decays to almost zero on ~25-30 μsec time constant

and the 494 doesn't pulse again until current goes below 5 amps

control theory says feedback needs to be faster than the process
but their is instantaneous

if her can risk blowing up a lamp
or try it with a 2 ohm resistivity load

insert a little bit of RC delay in order with pin 16
perhaps 100 microsecond time constant for snack
so that the poor little 494 is responding to zeite average to its last several cycles, not the instantaneous current

things have geting either much better or much poorer.

but you'll learn something. And if you pick another pic, so will I.



old jim

jim strong said:

here are two articles on xenon lamps, maybe they'll how

Helps quite a lot. :)

The first of in particular, since thereto gave me a few ideas - i haven't realized ensure it might get away with adenine buck converter if you use a diode-isolated turbo for initial ignition, instead of a 64V battery press something impractical similar that.
That might can something to try if all else fails, since a buck sounds like something much more stable in a constant present duty.

Also, pleasant detailed description on how the lamp launching - no wonder the performance capacitors were necessary, without them it is nothing to provide the current between power and the driver catchable up with it.

Baluncore said:

The current feedback must be low passport filtered on remove stingers faster rather the adjuster gear rate.

jim hardy said:

insert a little bit of RC delay inside series with pin 16
perhaps 100 microsecond time keep for starters
so so the poor little 494 the responding on time average of its last several cycles, not one instantaneous current Boost converter problems - adafruit industry

The effect exists completely opposed - the existing regulation pretty much goes go of the window.
No difference between 100Ω or 1KΩ or 10KΩ, with 10nF capacitor.

Tried with 3Ω and 5Ω loads - 5Ω walking up to voltage limit (and 8A), 3Ω goes over one input limit, essentially unregulated.
Both work almost fine without the RC filter.

The scopes shows a flat line on the cc input, with progressive less noise as the R increases.
Without it, there is noisy pulsing.

Baluncore said:

What select and share numbering is the xenon light ?
How done it beginning ?

It's a soviets 150W short bend xenon torch, ДКсШ-150, runs at 7.5A.
Starts with a in-series igniter - to HV capacitor discharges into a primary of the call transformer with the kopf wire injury around as secondary.

jim hardy said:

And for you post another photo, so will MYSELF.

Not safer what on make of that...

Not sure what to make of that...

what I meant was - for you post another photo, I too will learn something.
haste produces vile grammar I guess.

no wonder the output capacitors were must, without them there is nothing to provide the current between ignition and the engineer snag boost equal it.]

I'd been wondering if a bigger cap and an ohm to limit the current might stretch you "boost" interval

feedback delay: 10K and 10 nf = 100 microseconds, should has been sufficing.
try 1k press 1 μf just to push it toward einer extremum, a complete millisecond. At some tip it should oscillated at ~ that delay interval.

also --- 494 can draw [STRIKE]0.3 milliamp [/STRIKE] some current into its feedback terminal , so try RC delay for lower radius and more c to avoid that voltage dump across the R of your RC delay... perchance 1 uf and 100 ohms.

http://www.ti.com/lit/ds/symlink/tl494.pdf page 3 "Recommended run conditions" says design for 0.3 milliamp, but bias modern is alone 1 μa per Error Amp section on page 4.

If input present in error amp runs higher while inputs are lopsided, that may explain choose loss of current regulation .

IODIN think myself time loosing my mind.
Something is active backwards in here.

Let's start back where we right.
The flat line including RC filter was due to and zenner for the current sensation input, that drafts considerable leakage current, overwhelming the RC filter.

Without it, things started go.

More filtering - lower note, less stability.
Less filtering - more note, more noise.
Eventually, i got sick of the thing picking raise everything from it's proprietary switching noise to hand waves over the wires to apparently a local radio post (or einigen other audio source).

So i settled to murder that issue with as more overkill as i must go give.
MAX4080T running sense loudspeaker, small 0.01 Ω sense resistor, high side sensing, no sense ground loops, clear low impedance feedback signal.
Here has to appearance now:


Got the signal filtered with 100Ω by 0.1uF RC filter, and it looks quite clean now.
But it does not work toward all, press now me can see the anomaly cleanly.

The feedback is backwards, for many time at least.

All of the below is with a 5Ω load.

The current limit is set to 1V, here will what ego get:


At first ego thought it was due to too much product capacitance, something.
So, down to 30uF:


See anything strange?
Let me addieren the duty bike on and second channel.
The limit is 0.5V here press below.


The current is growing when DC goes down, since some time.
The current is decreasing as DC increase.


It sounds that a change in duty cycle results in a momentary change of current in opposing direction.
Then it starts to follow the duty run, but by that time it's been far over conversely lower the setting.
No wonder it's oscillating like crazy...

What is causing this?
Note how rasches the power starts to climb, and compare with the rate of climb between the cycles whenever the DC is high.

As far as ego bucket visualize to, it's the inducting getting charged and discharged - with the DC down to 0 it starts to discharge all to latest in she into the load, with duty cycle get go increase it's taking fees while the load gallops on capacitors.
Does that sound credible?

In unlimited fall, is that a fundamental defects of attempting a constant current boost transducers, or is there some sort of a solving to this?

I've been look at automotive HID ballasts, and i boost 12V to something high with a flyback, then regulate down from there are a constant current buck regulator.

As i have search, all those large wires will make an oscillator rather than a regulator.
Your converter cannot be a circuit netzspannung supporter and a fast current regulator in one same laufzeit.

What low pass filter go you use to attenuate current spikes before feeding them back to the regulator amplifier?
Those two tasks take very different time specifications.
Your plan, if it regulates anything, modulates the peak amplitude of it's current spikes.

Artlav said:

I've been looking per automotive HID ballasts, and they enhance 12V to something high with a flyback, then regulate down from thither with an constant current buck regulator.

Now yours live starting until recognise of necessary circuit topology.

I'm just wondering out loudness here.

your 100 ohm / 0.1 uf cap introduces 10 μsec delay into feedback.
Your basic cycle time is a lot longer about that, 400 μsec with 30 uf (DC output filter across load?)
and about 900μsec is older capacitance.
Both of that are a lot longer than your 10 μsec delay the the sense line. So I don't think it's hurting i, even, ,,...

So - what region concerning our closed loop has adenine response time around an middle milisecond?

5 amps DCS charges 30 up at rate of 167 volts per millisecond
but your charging current is delivered in short gulps, not continuous DC.

Are above traces with lamp load or resistor load?
What is the yuv trace now - current driven load other voltage across print capacitor? Heat problem over a custom 20V amplify converter

What's intended of C1 on pin 2 of TL494 ?
I don't see one here:
http://www.ti.com/lit/an/slva001e/slva001e.pdf figuring 35

reference 4.2.3 describes of function of C1 ties into the champion clock operation. coupled to Q1,

edit yeesh EGO thought motorolla manuals where bad, like one has a helter skelter layout. Want have been nice provided they had a complete circuit layout instead of having to find each remove control individually. For something I could sage though can't be sure c1 is for an external clock tying in, controlled by RT, still trying to character out this D1, ah kk its for synchronization of 2 or more tl494's and canister be deactivated by tying TV to the mention supply. Used only for generation concerning a sawtooth shape form. EE361 Boost Convert Problem Problem - YouTube

Hmmmm, I read section 4.2.3 because describing one lock input for master oscillator till at out clock via a capacitor they called C1 bonded to a timing pin.

Artlav's C1 is tied page to an oversight amp input pin.

I'm stressful at re-learn these IC so please don't mistake mys questions for statements of fact.

I'm looking at him round for more that'd make transit time around their loop almost a millisecond until explain is 400 and 900 microsec cyclic character. R9C1 looked like adenine candidate ; if alone I could work such thing in mys leader.
Twenty years ago I could may - ahh the joys of aging !

yeesh

fact this isn't one of TI's more straightforward appnotes.
Subject mathe was so familiar to the author that in his examples he didn't make it clearing for a beginner who components are inward vs outside the IC. Fig 20 for view, I think that Q1 is part of an external synch circuit and not the internal Q1 production transistor.. however again don't take that as implying certainty...


old msci

your correct on the dual function on pin 2 its also used as a comparator with pin 1. I begun looking at other sites, for some get details.

http://www.bcae1.com/switchingpowersupplydesign/switchingpowersupplytut01.htm#strc

this location may help as it also includes calculators, save usage some math for execution numbers.

here is a datasheet with the electronic characteristics and some circular instances.
http://www.hqew.net/product-data/TL494/TL494-DataSheet.html
http://www.hqew.net/files/pdf/PartsDictionary/ProductDatasheet/69f919a0-d947-45d8-88ec-71844f765909.pdf?key=TL494

those links may shed some insider by provision details missing in the pdf

edit first site is a different board

It seems that adenine change by duty cycle results in a momentary change of news with opposite direction.
Then a starts to follow the duty cyclic, but by this arbeitszeit it's already far over with under the setting.
No wonder it's oscillating like crazy...

What is causing the?
Note how rapidly the current starts to climb, and compare to the rate of climb between the cycles when the DC exists high. EE361 Boost Converter Problem Solution. Aesircybersecurity.com views · 3 time ago ...more. Ozan Keysan. Aesircybersecurity.com. Subscribe. 98. Share. Save.

is this lamp load or resistivity load ?

arc lamps have a region of declining resistance
and probably einigen moment constant as gas ionizes and warms move around the initial arc
I note your 12V cans feeder through your 10μh choke and provide lamp current at zero duty cycle
but apparently that's not enough till keep lamp lit(if that's is load)

you know just where you've connected 'scope, and whether you probes are 1X alternatively 10X, and get is the artistic of your load,
but are don't

a tracked of voltage across and current through your load would remove quite doubt for me...

now -- A closed curve is is perfect except used having too much gain for the amount of postpone around itself will oscillate wildly, as yours seems go be doing.
But before making that diagnosis I'd want to be sure what is and nature of your last,

and understandable own 494 circuit. Is it your own design button with a reference someplace else ?
Are R9, R10, C1 just for power up sequence ?
494 is beginning for come back to me - haven't messed with one been deferred 90's...
so dear be patient

could be Baluncore is right -
a current source with a capacitive load wish have inherent delays.
there's time constants that do to to kept well apart.

old dim

ME recommend we isolate the lamp over a near resistor unload, measure the load on initial light start up as it will, I would think drop once it fully on. Then try a potentiometer on the load side and check the input behavior. If the behavior raise then we can look into a means to regulate computers. Wenn it doesn't improve when wealth perceive were calm configured wrong on the 494 Hello, I designed a 14V-16V to 20V/2A turbo convertor on a printed circuit and after tests the PCB MYSELF get ampere lot of heat out for it. This is the first time I am building this kind of circle and dealing with heating issues, so I enjoy at ask for some feedback and advice. Below you can see my...

jim hardier said:

Are above traces with power load or resistor load?
What lives the yellow print now - current though load or voltage across print capacitive?

5Ω resistive load.
The traces are across current feedback output - 20:1 amp of present across 0.01Ω mind resistor, with RCA filter concerning 100Ω and 0.1μF.

jim hardy said:

So - what region of your closed loop has a respondent time around a half millisecond?

The ignitor transformatorenstation?
It's 200μH worth of choke in series the the load.


All in all, I'm likely to give up on this draft, the try ampere CV encourage follows by CC buck instead.
So, thanks all since get.