Transformator Flux balancing capacitor selection

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For a full bridge phase shift converter I need to place a series capacitor to the bridge transformer . This will prevent dc current in the trnsformer core and avoid core saturation.

 

The bridge has a Bus voltage of 540VDC. The switching frequency is 50khz-100khz.

)

The capacitor triangle current is (+/-) 30A peak to peak. 

 

In steady state the capacitor voltage is low. But if the duty cycle change in a short time is high ,the voltage on the capacitor rises for a short period of time.

 

The capacitor voltage rating is 800V-1000V. (regarding dynamic state and worst case with safety margin.). In steady state the voltage rating of the capacitor is very low.

 

I investigated film capacitors. But I noticed that they have a sharp decline of voltage rating versus frequency. For example a MKV polypropylene capacitor with a voltage rating of 1000VDC have only 25VDC voltage rating when driven by 10khz.

 

I am afraid that the only choice is the ceramic MLCC.

 

2 questions:

 

1- Which capacitor type would you prefer.

 

2- Is it more economic to limit duty cycle change range so that the voltage rating of the capacitor will be less. Is this method reliable enough? My regulation loop does not need fast response. So I can limit duty cycle change for a given time frame. This will introduce some problems for short circuits. 

If I change my control scheme from voltage control mode to peak current control mode, I can get rid of the capacitor but I think that voltage mode control has more advantage and more easy to implement for my application (requires significant less engineering work)

 

Any recommendations?

 

Thanks for your input.

 

 

This topic has a solution.

________________________________ We dream of a world where current does not need the voltage to flow.

Last Edited: Mon. Feb 11, 2019 - 03:56 PM
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I don't think ceramics a particularly good at high voltages either, in that capacitance drops off like a stone at high voltages.

 

I did see an installation where power factor correction capacitors were fitted. They were huge with substantial screw terminals and no doubt frightfully expensive. IIRC they were metallised poly-something film but of course only had to work at 50Hz.

 

I think you're into specialist stuff here and you may as well be building a flux capacitor. Although having said that I wonder what solar panel converters use.

 

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The Bus voltage of the LC network is 540VDC. (3 phase 400VAc rectified). 

 

In the simulation , If I choose an overdimensioned C like 100uF the voltage on the capacitor does not exceed 15Vpeaktppeak. The huge part of the voltage stays on the inductor.

 

But some design paper suggest to use high voltage rated capacitors even if the capacitor voltage does not exceed 15Vpeaktopeak in steady state.

 

I do not trust the simulation software in dynamic state. I can avoid huge changes of the PWM duty cycle in the embedded software code. But even then there may be some situations like ex. where i should handle shorted secondary of the transformer and in this case there may be a huge fluctiuation in the volt-second balance of the transformer. This may increase the voltage on the series capacitor. But I am not sure of that.

 

The critical question is that in an LC network if we choose overdimensioned C (ex 100uF) and a small enough L, can we *always* guarantee that in all working condition (both steady state and dynamic ) the voltage on C stays below a certain limit (ex: 20V) 

 

I assume the obligatory condition is that we are working far away from the resonant frequecy of the LC network. But even then I am not sure if some complication can occur at startup and shutdown of the network.

 

My working frequency ist 50khz.  The resonance frequency of LC circuit ist at 3.5khz.

 

I fear if at startup or shutdown some portion of the morphing frequency tends to get some amplification nearing the resonance frequency and the capacitor is damaged because of high voltage. 

 

  

 

 

  

________________________________ We dream of a world where current does not need the voltage to flow.

Last Edited: Sun. Feb 10, 2019 - 02:31 PM
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Way out of my league!

 

That said, I would love to see a photo of the setup when you get it up and running!

 

I still recall a few exploding caps when I was learning how to build a Xenon Strobe driver for a vehicle lightbar.

350V-ish at mA's of current, not 30 A!!!

 

Please be careful!!

 

JC

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The first implementation will be up to 15A @50khz.

 

If I stay far from resonance frequency of 3.5khz, it seems that the cap voltage will never go beyond 20V.

 

I constructed a capacitor bank consisting of 50V,10uF MLCCs because of cost optimisation.

 

The group1 of capacitor bank is made of  4 series connected 50V 10uF (MLCC ,case 1206), each balanced with 47k paralel resistor network.

Group1 resulting cap is 200V 2.5uF

 

x10 group1 connected parallel so the resulting cap is 200V, 25uF.

 

The resulting PCB with heavy copper (105um) ist poured into resin epoxy.

 

Does anyone have experience with balancing the series connected capacitors through paralel resistor networks when working under high frequency?

________________________________ We dream of a world where current does not need the voltage to flow.

Last Edited: Sun. Feb 10, 2019 - 04:03 PM
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This bit came up at Dangerous Prototypes recently for TDK CeraLink Capacitors - DC link, filter or snubber applications.

 

        App note: CeraLink® Capacitors 

 

The dielectric is a PLZT ceramic (lead lanthanum zirconium titanate), where capacitance increases with bias voltage.

 

There are three basic values of 0.25, 0.5 and 1.0 µF  with rated voltages of 900, 700 and 500 VDC. Available singly or in flex assemblies of 2, 3 or 10 paralleled capacitors.

 

They're quite impressive and pricey.

 

Last Edited: Sun. Feb 10, 2019 - 06:23 PM
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incal wrote:
For example a MKV polypropylene capacitor with a voltage rating of 1000VDC have only 25VDC voltage rating when driven by 10khz.
This limitation is probably (I'm guessing here) due to heating.

Just for fun: Calculate the current through your capacitor @1000Vac and 10kHz.

 

incal wrote:
But some design paper suggest to use high voltage rated capacitors even if the capacitor voltage does not exceed 15Vpeaktopeak in steady state.
Yes, of course. Your capacitors will have to swallow high peaks during switching, and you want them to survive that.

 

It seems like tye MKV you selected earlier is perfect for the job. It can withstand the 500V peaks and during normal operation you apparently have 15Vac over your capacitor, which is also within your specified limits.

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Yes, I believe I should design the LC tank so that in steady state the capacitor voltage does not exceed 20V. At start up and shut down or for transformer secondary short circuit handling routines , there may be moments that the morphing frequency accidentally or mathematically gets near to resonance frequency. This can induce for a very short period of time a high voltage on the cap.

 

And for this purpose it seems that the polypropylene MKP is the right choice. It is also the most expensive solution. (everything has its price).

 

The regular MLCC (except the ones with special PLZ ceramics from sbennet's link above) are probably less reliable than MKP caps.

 

Thanks for the recommendation.

 

Edit:  this is the link of Kemet 1uF 1000VDC (275VAC) capacitor: At page 6.

 

At 10Khz Voltage Rating is 80Vrms

    20khz Voltage Rating is 45Vrms

    30khz Voltage Rating is 30Vrms

    50khz  Voltage Rating is 20Vrms.

 

At my working frequency of 50khz , it is suprisingly on the limit.  They cost 0.3Euro/each for a quantity of 1000 (mouser). So my 25uF cap. bank will cost 7.5 Euro.

I think this is the cheapest alternative.

 

 

http://eu.mouser.com/datasheet/2/212/KEM_F3030_R71-1314182.pdf

 

________________________________ We dream of a world where current does not need the voltage to flow.

Last Edited: Sun. Feb 10, 2019 - 08:59 PM
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They seem to be excellent capacitors. But IMHO for 25uF @1000V they will be much more expensive than the alternative film capacitors.

 

For this kind of severe current range jumping from -15A to 15A, I also can not predict if the ceramic body mechanically withstand the osscilations. A series connected pulse capacitor carrying the whole line current with a ripple current of +/-15A is a very different story from a smootening or snubber capacitor. 

 

They are really expensive:

 

700VDC 1uF cap cost around 13.5 Euro/each for a quntity of 1000. My 25uF cap bank should cost around 337.5 Euro. The film capacitor bank costs around 7.5 Euro, but is not the 1:1 alternative. 1000Vdc film cap has only 20V Voltage rating at 50khz. 

 

http://eu.mouser.com/ProductDetail/TDK/B58035U7105M062?qs=sGAEpiMZZMtGtrSL1omHbHPJTSb0%2fcOqdqjlg8RO1I8%3d

________________________________ We dream of a world where current does not need the voltage to flow.

Last Edited: Sun. Feb 10, 2019 - 08:59 PM
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When in the dark remember-the future looks brighter than ever.   I look forward to being able to predict the future!

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Thanks for the links. I have investigated the above links a while ago. The problem is :

 

If you increase C the voltage stress on c decreases, but you will need to increase the resonant inductor so that the minimum current where the soft switching begins remains low. This is not so straighforward. They don't explain in the paper (chineese) how they overcome the problem that the minimum current for the soft switching becomes too high. It would be better that they give the Lr and Cb values so that I could simulate it to see if the claims are justified.

 

If you decrease the value of C, you have more room for soft switching because the inductor has enough energy to balance the enegry stored in Capacitor. But then you face 2 main problems: 1-The voltage rating of the capacitor will be very high and it will be very expensive. 2-This will also limit the power transfer and duty cycle.

 

All these can be overcomed by nearing to resonance frequency and controling the power flow through a kind of frequency modulation. It is the famous LLC converter. But it has also drawbacks. 

 

Short: Nothing is perfect.  

________________________________ We dream of a world where current does not need the voltage to flow.

Last Edited: Sun. Feb 10, 2019 - 10:34 PM
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incal wrote:
25uF @1000V 
Aah, a value for a capacitor.

 

If I remember well, and toying a bit with Octave:

 

octave:1> f= 10000
f =  10000
octave:2> W= 2*pi*f                  # W = Omega, my greek ain't too good.
W =  62831.85307
octave:3> C=25e-6                    # 25uF Capacitor.
C =  0.000025000
octave:4> i
ans =  0 + 1i                        # Gosh, Octave understands complex numbers (Never tried that before).
octave:5> Z= -i/(W*C)
Z = -0.00000 - 0.63662i              # Impedance of capacitor.
octave:6> abs(Z)
ans =  0.63662
octave:7> 1000/ans                   # Voltage / impedance = Current.
ans =  1570.8

I think it's somewhat understandable that a cap that can handle 1500 Amps @ 1000V is going to cost some money, and even at 20V you're looking at serious currents. ( 31.416 A).

I may have made some gross error in this calculation, my head has been a bet cloudy lately, so please check the numbers.

A maximum of 30A sounds reasonable though for a "normal" capacitor.

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Yes absolutely true,

 

Q=C.V

 

And unfortunatelly, it is not a resisitive element. It means any fluctuations in V means the existence of current. they are connected.

 

dQ/dt = C. dV/dt

 

And if we are talking abaout frequency, it means that dV/dt must be huge so the term dQ/dt. dQ/dt is nothing others than the  I, current.

 

Passing huge amounts of current through huge dV/dt means extreme power dissipation:

 

W= 1/2 * C* V^2.  This is the stored energy, but the dissipation is also very high because of very high ripple currents.

 

Thanks for your input.

 

 

 

 

  

 

________________________________ We dream of a world where current does not need the voltage to flow.

Last Edited: Mon. Feb 11, 2019 - 06:30 AM
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have you actually tried looking at sites of manufacturers directly?

 

I have found in the past that although you give a number of parameters in a distributors search engine that all the results come up.

you could try avx, kemet, panasonic, tdk, Yageo see if they have capacitors in their inventory. Then with the real part numbers check at the distributors end if they have them or similar ones.

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I investigate the distrubutors inventory (mainly mouser). 

 

My main problem for MLCC ceramics is that the ESR is not well defined.

 

For example for the film cap 1uF, 1000VDC the internal ESR is given as 9mOhm. If I=15A. I can calculate that the power dissipation is 15x15x0.009= 2watts. The case of film caps are huge (27.5mmx10mmx15mm). So I can be sure that 2W is compatible for the dimension of the case.

 

But for the ceramics there is a problem with the ESR. Ok, we know that it is very low, but as far as I noticed in the datasheets it is also heavyly frequency dependant.  I can not calculate it precisely. Is it 10mOhm or 1mOhm?. Not clear from the logaritmic graphs that is available in the datasheets. The case of the ceramics are also very small. So any misscalculation of the effective ESR will destroy the chip . think how small is the 1206 case. It can definitely not dissipate 2W. There is also the risk of a mechanical crack.

 

I investigate further.

________________________________ We dream of a world where current does not need the voltage to flow.

Last Edited: Mon. Feb 11, 2019 - 07:23 AM
This reply has been marked as the solution. 
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Some folks have a hobby of heating things with an induction coil.

The Chinese accomodate this by making ver cheap kits.

They consist of a tank circuit made from an inductor in the form of a copper pipe and fairly beefy film caps.

(They also have some MOSfets to pup power into the circuit).

 

"ZVS" (Zero Voltage Switching) is a good magic word to find them:

https://www.aliexpress.com/wholesale?SearchText=zvs+induction

 

These boards come in lots of different sizes.

The Capacitors all the different Chinese use for these things look like:

(Often thyey are black instead of blue)

 

 

This is a fairly big picture, which makes the markings on the capacitors good readable:

MKPH

630V ac/dc

(1200 V - )   ???

50kHz

From what I know these capacitor have higher specifications than regular MKP's, which would probably desolder themselves due to internal heating.

 

 

I'm under the impression that Western shops ( MOuser, Digikey, Farnell and all the others) have gone completely bonkers.

Sometimes I think the've made a Kartel to keep prices high, but it could be that they are just doing what their neighbour is doing, or following 30 year old traditions.

Just take one of those shops and look at prices of small SOT-23 Fet's.

They are somewhere between 20ct and 45ct each. 

Buying such components from (possibly unerilable) shops on Ali they tend to cost around 2ct each (in strips of 50 or 100).

Reputable stores such as LCSC in China is a bit less cheap (around 3 to 7 ct) but still almost 10x cheaper than the regular western shops.

They also simply do not sell separate SOT-23 chips, it's not worth it. Pricing starts at cut tape of 10 pcs.

The regular western shops sell single pieces (which I find fairly redicilous) and if you look at their 1000 or 10000 up price they often do not drop much.

 

Therefore I recommend to have a look at LCSC for the capacitors you want.

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Last Edited: Mon. Feb 11, 2019 - 06:52 PM
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Perhaps have a look at the vendors directly.

I have had in the past that I gave a couple of search criteria and nothing would pop-up. Then when I went to a vendor directly they had what I was looking for. typed that order number in then farnell and all of the sudden they had them in their product portfolio.

Also have had that while typing that specific ordernumber I saw that they did not have the exact match, but a couple of alternatives came up that I checked and could use.

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incal wrote:
They seem to be excellent capacitors. But IMHO for 25uF @1000V they will be much more expensive than the alternative film capacitors.

What is driving your price decision? Are you planning to build hundreds of these units?

Scotty: A good engineer is always a wee bit conservative, at least on paper.

Always design for the worst case scenario, better to have the best design, rather then the cheapest, as it is your reputation that is at stake!

 

Sounds like a very interesting project, good luck with it!

 

Jim

 

 

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incal wrote:

The first implementation will be up to 15A @50khz.

 

If I stay far from resonance frequency of 3.5khz, it seems that the cap voltage will never go beyond 20V.

 

I constructed a capacitor bank consisting of 50V,10uF MLCCs because of cost optimisation.

 

The group1 of capacitor bank is made of  4 series connected 50V 10uF (MLCC ,case 1206), each balanced with 47k paralel resistor network.

Group1 resulting cap is 200V 2.5uF

 

x10 group1 connected parallel so the resulting cap is 200V, 25uF.

 

The resulting PCB with heavy copper (105um) ist poured into resin epoxy.

 

Does anyone have experience with balancing the series connected capacitors through paralel resistor networks when working under high frequency?

I am fascinated by the thought of distributed capacitors.

 

I suspect that they will fail in a sequence as opposed to a BFC that just explodes with a single bang.   e.g. electrolytic

 

Film capacitors probably self heal but I certainly don't want to be near your product.

The effective capacitance will be reduced as the holes develop (assuming the heat has not caused catastrophic failure)

 

When you are dealing with 440V 3-phase power components are inevitably more expensive than AA-powered consumer devices.

Price competition is not that fierce in the industrial market.    But your company's reputation would be ruined by a serious accident / failure.

 

David.

Last Edited: Mon. Feb 11, 2019 - 02:20 PM
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It is not just the cost issue, it is more a design issue. Some TI documents and other reserch papers claim that the voltage on this capacitor stays very low. 

 

Think abaout a simple LCR tank with 200uH + 47uF + 0.1 Ohm.

 

Let the bus Voltage be 540VDC. you have the bridge semiconductors switching (50khz) far from resonance frequency of the LC network. (Fres=1.64Khz)

 

If we think pure mathematically, it is not possible that the voltage on C goes above 20Vpeaktopeak. At these frequencies all the voltage stays on the inductor.

 

I investigate the possibility if there is real life any scenario that C goes above 20Vpeaktopeak. 

 

If I can be sure of the start up and shut down sequences, I will construct a MLCC capacitor bank and try it.

 

Just from the mathematical part, do you think that there is danger at start up and shut down of the system. The system starts with a phase shifted full bridge with truely %0 duty cycle and ramps up to %50 duty cycle with fine increments. And the shut down is vice-versa. There are also freewheeling diodes. 

 

Anybody have a sense and feeling if there is a mathematically a possiblity that the voltage on C increase above 20V. I am %90 certain that the inductor will not let that happen. smiley

 

Any ideas?

 

 

 

 

________________________________ We dream of a world where current does not need the voltage to flow.

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There is no 20V voltage limit.

 

The "20V limit" you found in the datasheet is most likely because of the current.

25 uF capacitors have very low impedance @ 50KHz.

In #12 I showed that you need more than 1000A to get a significant voltage over your cap at 50KHz.

 

If you want to increase the robustness of ceramic capacitors it can help to have a big PCB area for cooling and also lots of solder on the ends.

 

Some time ago I worked with a "soft starter" (for a 5kW induction motor). Instead of a big piece of aluminimum with loads of cooling fins it had just a blob of aluminimum with some small fins.

The idea was that the thermal capacitance of the aluminimum absorbs all the heat during a start event, and then can dissipate it to the surroundings at a leasurly rate.

These "soft starters" are often rated for only a few starts in a short time.

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Dear paulvdh,

 

I also trust the mathematics that the voltage on the cap has a severe limitation at 50khz.

 

What do you think abaout this ceramic bank:

 

group1 : 10x 1210 50V 10uF paralel

 

2x group1 series placed on heavy copper pcb. Resulting 100V 50uF.

 

The whole pcb will be dipped into a special resin with a very high thermal conductance and at the same time a very high insulation resistance. This mixture resin is also my amateur construction with a mixture of epoxy resin mixed with very fine 5um aluminium oxide powder. (Al2O3)

 

Do you think that this capacitor bank can handle +/-15A continiously. 

 

I could not find any ESR data for standart MLCC 50V 10uF. Anyone has a guess?  1mOhm? 5mOhm?

 

Each cost 0.071 Euro. And the capacitor bank costs in total 1.4 Euro.

 

http://eu.mouser.com/ProductDetail/Taiyo-Yuden/UMK316BBJ106ML-T?qs=sGAEpiMZZMs7ZEmUmaUL05pJtAILgU%252bsqWuaovKYFnU%3d

 

Datasheet: I find nothing abaout the ESR.

 

http://eu.mouser.com/datasheet/2/396/mlcc02_e-1307760.pdf

 

 

________________________________ We dream of a world where current does not need the voltage to flow.

Last Edited: Mon. Feb 11, 2019 - 06:31 PM
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I don't think 7ct capacitors are going to perform very well in your application.

From the datasheet you linked:

Charge/discharge current 50mA max. 

I also do not have any experience with your: "full bridge phase shift converter" but I guess you need the high voltage ratings of your capacitor for robustness during switching events.

 

Doing magic with a USD 7 Logic Analyser: https://www.avrfreaks.net/comment/2421756#comment-2421756

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Dear Paulvdh,

 

I looked at the datasheet and it seems that the test for withstanding voltage and insulation resistance are performed with 50mA charge discharge condition.

 

I am not sure but they may not be the current rating of the capacitor but the test current where the withstanding maximum voltage and the maximum insulating resistance tests are performed.

 

50mA discharge current is for a 50V 10uF MLCC unreasonable low.

 

I find it very suprising that MLCC manufactorers does not mention proper ESR value. 

________________________________ We dream of a world where current does not need the voltage to flow.

Last Edited: Mon. Feb 11, 2019 - 08:24 PM
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You should take it as a hint that those capacitors are not tested nor specified beyond those 50mA.

Then compare it with the data found in the datasheets from the capacitors (such as) from post #16.

incal wrote:
I find it very suprising that MLCC manufactorers does not mention proper ESR value. 
They do specify a Q factor @1MHz for those capacitors, you can back calculate some ESR value Equivalent from that. The Yageo link below also gusstest that ESR for MLCC's is not a constant, but varies with frequency.

Or it is so inherently low that it is not measurable in a meaningfull way.

Have a look at various datasheets of MLCC's of different manufacturers. Sometimes you find for example graphs where impedance versus frequency is plotted.

A quick search:

https://duckduckgo.com/html?q=MLCC+ESR

Finds:

https://www.murata.com/en-us/support/faqs/products/capacitor/mlcc/char/0016

This PDF from Yageo has some graphs where ESR is plotted over frequency, and has other interesting background info about MLCC's.

http://www.yageo.com/exep/pages/download/literatures/High%20Capacitance%20MLCCs_2012.pdf

 

I like the info regarding capacitance variance versus bending stress and mechanical stability of these capacitors.

The ceramics is quite brittle, sometimes there are somewhat elastic layers added between the ceramics and the solder pads to reduce sensitivity to the scenario's below.

 

 

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Dear Paulvhd, thank you for the excellent link , simsurfing.

 

MLCC 50V 10uF  case 1206   ESR @20kHz = 30mOhm     (suprisingly high, higher than film capacitor which was 9mOhm)

 

MLCC 50V 10uF  case 1206   ESR @50khz =  10mOhm

 

MLCC 50V 10uF  case 1210   ESR @20khz = 6mOhm

 

MLCC 50V  10uF  case 1210  ESR @50kHZ = 3 mOhm.

 

This shows that if MLCC is chosen 1210 case is the way to go.

 

Through this data the problem reduces itself to mechanics if I look at the bending positions on the illustration above.. 

 

The current rise is:  30A/10us = 3A/us . How big is the effecting force on ceramics (whole capacitor bank) when stressed by 3A/us ?. this is an important question. 

 

Some 50V 10uF cermaics had a very loud sound. I thought that the circuit is malfunctioning. But it was not the case. Thay have a very high piezoelectric ultrasonic sound radiation. If you place one at top and another at bottom side of PCB they tend to cancel the vibrations. But it is always a risk.

 

The volume of MLCC capacitor bank is x100 smaller than the film capacitor bank of 25uF. 

 

MLCC has excellent electrical characteristic. But the mechanical crack risk is the biggest question.

 

Film capacitor (even the cheap chineese MKPH) has big volume but is mechanically more reliable.

 

As Jim (ki0bk) expressed, If i feel the risk, I will tend to use the most reliable solution even if the volume is x100. 

 

I tend to feel that the relative bullet proof selection is the Film capacitor. 

 

My device is a constant current supply delivering 1000A @10V having a volume of 3.6 dm3.

 

Just the Film capacitor will increase the device volume up to 4 dm3.

 

The 1000A units are paralel stackable to form a current output up to 50.000A.  

________________________________ We dream of a world where current does not need the voltage to flow.

Last Edited: Tue. Feb 12, 2019 - 07:59 AM
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incal wrote:
The 1000A units are paralel stackable to form a current output up to 50.000A.

WTF: You were seriously considering delivering that amount of power through a few 1206 ceramics.

 

BTW: I investigated the generic solar panel converter I mentioned in #2. It seems these are now at the pinnacle of design in terms of cost/size/MTBF/temperature-range. It seems they could only achieve the highly demanding requirements by going transformerless alongside active control of the H bridge by a microcontroller.

 

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N.Winterbottom wrote:

incal wrote:
The 1000A units are paralel stackable to form a current output up to 50.000A.

WTF: You were seriously considering delivering that amount of power through a few 1206 ceramics.

 

BTW: I investigated the generic solar panel converter I mentioned in #2. It seems these are now at the pinnacle of design in terms of cost/size/MTBF/temperature-range. It seems they could only achieve the highly demanding requirements by going transformerless alongside active control of the H bridge by a microcontroller.

 

 

Transformerless is for me no option because my secondary current is very high and secondary Voltage is very low. 

 

I believe that mathematically and especially from the electrodynamic aspect, it is possible to pass 10kW of power @50khz through a capacitor bank of x20 MLCC 50V 10uF ,case 1210 (x10 parallel) x 2 series acting as a part of LCR network supplied by 540Vpeaktopeak at 50khz.

The major part of the 540Vpeaktopeak stays on the inductor. 

 

But I believe the main problem is the mechanical brittleness of the ceramics. They are not reliable. But pure electrically, 50uF 100V MLCC capacitor bank can pass 10kW @50khz. (inductor part carries the most part of the network voltage at roughly 525Vpeaktopeak because at 50kHZ, we are very far away from the natural resonance of the LCR network which is at 1.64Khz) 

 

________________________________ We dream of a world where current does not need the voltage to flow.

Last Edited: Tue. Feb 12, 2019 - 10:06 AM