Choosing Full Bridge Driver.

Thread Starter

james31207

Joined Sep 19, 2018
72
I want to use the H-Bridge module shown in the attachment as a switch in a 12V DC circuit and would prefer if possible, for ease and simplicity, to use a full bridge gate driver such as the IRS2453DS [Data Sheet attached]. The H-Bridge comprises 4 IGBTs, rated for 75A, and the intention is for a very slow switching rate of 4 to 8Hz. From the data sheet [p.3], the gate capacitance of these IGBTs is about 4.3nF and gate charge 166nC. The saturation voltage is 15V and Vgs threshold is ~4V. (Gate-Source leakage current 120nA).

Because the switching rate is so slow -- on/off periods in the millisecond range --, my understanding so far is that the sink/source currents of this specific gate driver are sufficient to the gate capacitance involved. The bootstrap capacitor incorporated is 0.1 microF, well above the gate capacitance.

My question then is whether, broadly speaking (if such is even possible in electronics), this full bridge driver is even anywhere close to appropriate for such an application, and if not, why not? Any guidance would be much appreciated.
 

Attachments

LowQCab

Joined Nov 6, 2012
271
For what application ?????
You didn't state the problem you are trying to solve.
What is the "12 Volt Circuit" controlling ????
What are the Voltage and Current requirements ????
Is this mystery circuit supposed to be creating a square wave ???, for what purpose ???
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Thread Starter

james31207

Joined Sep 19, 2018
72
Well, the application of the full bridge driver would be to supply 15V between the gate and source/emitter pins of the high side IGBTs. I had intended to use separate gate drivers, specifically the UCC 5390 from TI about which I'd posted a previous thread here; but having discovered later that a 4 channel gate driver actually exists, wondered whether by sheer luck, there might be such a device which was appropriate for the switch I'm trying to design -- without as you probably appreciate any experience in electronics. It took me a year just to discover the H-Bridge.

The purpose of the H-Bridge switch is to reverse a 50A current at 12V in order to switch polarities in electromagnets powered by that current at 4 to 8 Hz in order to create a rotating magnetic field, and the shape of the resulting 12V DC wave doesn't matter too much for the purposes of the project and its prototype. I'm not even sure whether the H-Bridge can handle the back EMF arising from this switching, and will not proceed with the experiment without further technical assistance; although for the time being I'm presuming it can.

So, since all this seems on the face of it to be a fairly straightforward situation electronically, I'm asking mainly whether there is any obvious reason that a full bridge driver wouldn't be the best choice to provide the necessary voltage and current to these particular gates. My own unlearned impression is that it's probably simpler to use separate HS and LS gate drivers, and I'll be doing a bit of work on the LTspice simulator to figure that out too.

Any guidance informed by experience however would be much appreciated.
 

LowQCab

Joined Nov 6, 2012
271
You don'y necessarily want to SLAM those Coils with a sharp edged waveform.
Yes, that keeps the transistors cooler, but you may be setting up all kinds of other problems by doing that.
What RPM Range is this Motor going to be used in ?
Are you building a Motor from scratch, or are you using an existing design ?
Have you considered the level of RFI that you are going to have to filter to keep it out of the rest of the car ?
Hard/Fast switching with already fast IGBTs WILL generate noise and Ringing, and will generate additional HEAT.
The solutions to this need to be worked out in Simulation Software as accurately as possible,
then there's what actually happens in the real world.
Slowing Down the switching speeds can be very advantageous in many respects, when it comes to Motors.
This doesn't appear to be a 3-Phase Motor, how do you intend to start it ? A Rotary Encoder maybe ?
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Thread Starter

james31207

Joined Sep 19, 2018
72
It isn't a motor; it's an experimental apparatus whose central feature is a rotating magnetic field intended in the first place to drive a permanent magnet around on an axis at something like 500 rpm. If you're really interested, you can check out the presentation at; http:/magneticcorepropellergenerator.blogspot.com

It's an old blog from around 2012, but should give you a good idea of the thinking involved. I could have had the thing going 20 years ago if it weren't for the problem of a switch which, after exhausting electro-mechanical possibilities such as using commutating plates and brushes in the DC circuit to the 12 field coils shown, is inevitably an H-Bridge electronic switch.

Obviously I cannot build an H-Bridge using MOSFETS so I settled for a prefabricated module using IGBTs; which should be alright once I figure out how to hook up the gate drivers, and bootstrap circuit; since the IGBT gates need 15V for Vgs. 'MaxHeadRoom' came through with his usual gem, so I might even end up trying the IR2110 HS/LS driver explained at Tahmid's excellent blog, if I can sort out whether it's suitable for these IGBTs -- which seems reasonably likely.

And yes, I've just discovered LTspice simulation, so I'll try to learn about that over this year. It's not easy learning new disciplines when you're virtually a geriatric. And sure, there'll be plenty of RFI if ever this ridiculous contraption starts spinning continuously, so I hope it doesn't knock any satellites out of orbit or anything.
 

LowQCab

Joined Nov 6, 2012
271
A conductive Ferro-Magnetic Fluid in a sealed hollow ring shaped pipe works better.
At around 8 feet in diameter, with a pipe size of ~10",
it works so well that it creates Gravitational Anomalies up to ~100ft. away,
right through steel reinforced concrete.

You will NOT FIND anything that actually works on the Internet.
All the stuff that works has been scrubbed and buried, usually along with its inventor.
But there's good news,
it will only be a short while now until these types of very interesting technologies are revealed to the Public,
but you'd have to have been following Politics, as well as Technological Advances, for decades,
before you could put 2 and 2 together.
Throw away your TV, and be careful,
because this Forum has a written policy of Censoring any information regarding the subject of your type of pursuit.
Ask me how I know .....
Pretty astounding really, it's right in the TOS for this site, in black and white, but few people have ever read it.
So, don't mention what it is that you are building here.
In fact, if I were you, I would go back and edit your post to remove any ""objectionable"" references or Links.
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Thread Starter

james31207

Joined Sep 19, 2018
72
It's nothing sinister, just an experiment really (and as far as I know, an original notion). I'm interested in the type of current that this apparatus might generate, and in particular if it is potentially useful in the more efficient electrolysis of water -- and at the moment, after meditating on it for decades, I can't imagine what other uses it might have. Also, I'm not the slightest bit interested in whatever other gizmos of dubious motivation and intent are advertised, publicised or otherwise promulgated on the internet. I'm here at this forum to learn something from people whose familiarity and expertise in electronics still astonishes me.
 
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LowQCab

Joined Nov 6, 2012
271
When it comes to Water,
the trick is to study-up on the separation angle of the Hydrogen Atoms and what affects it.
The Angle is not fixed, like many people assume,
and you want to do everything possible to make the angle as wide as possible
BEFORE you start using brute-force power to separate one of the Hydrogen Atoms.
Temperature is one key factor,
so using any form of wasted heat that you can collect to raise the temperature first,
is going to be a bonus.
I'm thinking that pumping the water through an extremely powerful pulsed Magnetic Field,
repeatedly, is going to be the trick to raising the efficiency of this process.
Finding the exact Resonant Frequency of the Molecules may play a pivotal role in how this may work.
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Thread Starter

james31207

Joined Sep 19, 2018
72
Yeah, it would be something like unscrewing the tendency for Hydrogen and Oxygen (in their local marriage of cosmic convenience) to assume the relative stability of 'oscillatory tetrahedra' (which is a loose geometric description of the fundamental form of a unitary universal oscillatory wave principle manifesting or focusing in its most rudimentary form), using the amazing leverage of a helical voltage waveform to untwist hydrogen bonds and then knock the hydrogen off its perch, where it would rather not be anyway, and put it to flight.

Obviously I have a somewhat more precise image of the physics of such a manoeuvre in mind (too cumbersome and outlandish to go into here), and the technical implementation of it would be far beyond my capacity even were the generator in question to yield the requisite output, but the evidence that every green leaf on the planet performs this process of hydrolysis continuously in the presence of light with presumably optimal efficiency by virtue of minuscule electromagnetic currents and fields is there for all to see, isn't it (as is the effect that the same process in reverse, that of reduction of Oxygen directly to water, is occurring continuously in the trillions of mitochondria in mammalian bodies; through the enzyme Cytochrome Oxidase with its peculiar helical structure and monovalent Fe+ and Cu+ ions ordering things there).

And you know, Hydrogen gas, while eminently useful, is just one thing -- but it'd be nice wouldn't it to be able to electrolyse salt water efficiently with extremely small electrical currents (from a generator powered by a DC battery hooked up to solar cells), transport it to a desert and use it as a fuel whose product is clean fresh water. First though, the switch for which I might end up using IR2110 drivers. Your thoughts are welcome and gratefully accepted. j.
 

shortbus

Joined Sep 30, 2009
8,429
check out the presentation at; http:/magneticcorepropellergenerator.blogspot.com
Not that crap again! No matter how many fancy words the guy put in his presentation it won't work. It was presented here before and shot down. Having permanent magnets rotating with the coil is not going to generate any electricity.
 

Thread Starter

james31207

Joined Sep 19, 2018
72
Now now Shortbus, that's just your opinion; and nothing was ever 'shot down' here. You may be right of course, but I don't think you've really looked very closely at the whole design.

I don't really want to argue about it here either, but you should realise that just because the winding is rotating with the helical magnetic core does not mean that that winding is not exposed to significant changes in magnetic field flux [dB/dt] arising between the permanent magnets in the core and the external magnetic field produced in the 12 surrounding electromagnets (also driving that core around), both at the points at which the winding abuts the core (which are pinion points for the rest of the effect) and more importantly in the rest of the winding more remote from the core, which is most of the winding: lots of oblique components being generated at all times in the rotation cycle over the entirety of the winding. The only question is whether they integrate within a singular dynamic effect; which sounds like an interesting experiment doesn't it. ''Come on!''

There is no doubt that some sort of current will be generated in that continuous singular progressive lap-type and therefore coil-like winding -- it's like a real coil --, and it is the simple aim of the experiment to determine its character and properties. That's all. Oddly too, a few months ago I came across 'Faraday's paradox', so you might want to apply your mind to that at some point as well. Faraday.

In the meanwhile, I'm very grateful for your help trying to build the switch necessary to drive the core, which already goes through 135 degrees without any trouble until it stalls because the polarities in the EMs need to reverse. However, I'm working only intermittently on the whole project and in quite isolated circumstances, so everything takes forever to get done. Maybe you're right that it will all come to naught in the end, but it will not be because I was either daunted by anyone's impression that it wasn't worth pursuing the idea, or because I just gave up trying like a pussy.

So, concerning the high side gate driver, are you saying that in order to use the same 12V source for the H-Bridge and the output side of the driver, I'd basically wire them in parallel from common +/-- terminals?
 
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shortbus

Joined Sep 30, 2009
8,429
Now now Shortbus, that's just your opinion; and nothing was ever 'shot down' here. You may be right of course, but I don't think you've really looked very closely at the whole design.
Were/are you the guy who was posting about this before? Oh I did look at and read the link, several times, when this idea was on the forum before. Like I said he uses some real pretty words, and some pretty drawings, but when you read it with an open mind and looking at both physics and how things work in the real world, pretty is all it is. The whole thing is nonsense. If it works and he has made it work, why doesn't he show it? Why hasn't he ever gone past the stage of making it from wooden parts? Why if this is a viable machine do all other alternators use iron in the rotor to make use of all of the available magnetism? Are you saying you will get more power out of this than you put into the driving solenoids? Just too many questions that no one seems to have an answer to.

As far as you trying to do this with discrete components, why not just use a stepper motor driver? That will give you all of the reversal of poles fairly easy and with no building.
 

LowQCab

Joined Nov 6, 2012
271
I would generally tend to agree that much of these types of pursuits do look somewhat absurd,
but I would never tell anyone not to keep pushing the envelope of possibility.
Only 300 years ago you would have been put to death for committing heresy if you
simply stated that the Earth was round, or that you could produce Lightning in a bottle.

Likewise, today you can be "disappeared" if you become too successful at the "wrong thing".
I spent ~3 years researching why no one had come up with my Engine Invention decades earlier than me,
and that is specifically why I did not apply for a Patent.
I did the research at the Patent Office in DC, and there is nothing even close to my invention on record,
but I did find plenty of completely impractical "Rube Goldberg Devices" supposedly to
replace our ridiculous, ~130 year old Piston Engines.

All of these current bad/stupid, circumstances/situations, will be changing drastically within the next 2 years.

I think James needs to be thinking in the direction of 3-Phase AC, rather than a Square Wave.
In that case, a 3-Phase Motor Speed Controller is all that is needed to control
both the Voltage/Current, and the RPM/Direction, of the Rotating Fields.
I'm sure one could be found used on Ebay, or a cheap new one from China on Ali-Express.
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PRASS

Joined Feb 22, 2018
30
Yes & no at the same time.
I myself am trying to construct 200VDC Bridge Driver to run a DC motor.
After I have tried a IC type drivers I was extremely dissapointed that the slow rate of discharge combined with the ESD from the motor itself causes gate threshold breakdown & short circuits.
I have even tried building them from 2 N chanel & 2 P channel mosfets straight bridging the gates with the same short circuit results.
I have now resigned to the fact I will be using the same 2N & 2P mosfets but will be using an external microprocessor like an Arduino to drive them so I can give a small wait time to let everything discharge before switching polarities.
 

Thread Starter

james31207

Joined Sep 19, 2018
72
@james31207 Did you find a solution to your bridge driver problem? Was Max Headroom's link in post #4 what you needed?
Max's link was exactly what was required, especially because at my level of inexperience, I can follow the sense of the circuitry; I have studied it and wanted to ask a couple of questions. For example, when I first began investigating gate drivers, people here immediately suggested isolated gate drivers, while elsewhere others have noted that for a 12V supply to the H-Bridge -- Vds [or Vce] --, an isolated gate driver is not needed. The IR2110 is not an isolated gate driver, so I wonder whether it is suitable to drive these IGBTs.

The other thing concerns the capacitance of the C1. Tahmid seems to use a rule of thumb relating the size of this to frequency, which means that if the calculation he's using is broadly linear, I'd need about 0.5 mF. The further part of this is that, if C and Resistance are related C x R = t, does t then refer to the turn on period of the high-side gate [Q1], which at a frequency of 5Hz for example is 200 milliseconds; and if so, does this imply a total resistance in the output side of the gate driver circuit of 400 Ohms in that case? Or what? Evidently not [See Edit below].

That's mainly what I need to know just now if you've got a moment.

EDIT: This relation of C and R seems to apply to the specific case of charging and discharging the capacitor C in a circuit -- an RC circuit -- with a switch and resistor R in which the voltage across the capacitor Vc reaches equilibrium with the source voltage V. The time t for charging or exponential decay of the capacitor charge correlates with the time constant T of the system.
 
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Thread Starter

james31207

Joined Sep 19, 2018
72
Were/are you the guy who was posting about this before? Oh I did look at and read the link, several times, when this idea was on the forum before. Like I said he uses some real pretty words, and some pretty drawings, but when you read it with an open mind and looking at both physics and how things work in the real world, pretty is all it is. The whole thing is nonsense. If it works and he has made it work, why doesn't he show it? Why hasn't he ever gone past the stage of making it from wooden parts? Why if this is a viable machine do all other alternators use iron in the rotor to make use of all of the available magnetism? Are you saying you will get more power out of this than you put into the driving solenoids? Just too many questions that no one seems to have an answer to.

As far as you trying to do this with discrete components, why not just use a stepper motor driver? That will give you all of the reversal of poles fairly easy and with no building.
Same guy, same idea (which is not to produce large quantities of electrical power or motor torque)-- and yes, the relation between the rotor core (permanent magnets) and the stator coils is similar to a stepper motor; however the design is not intended as a motor, but as a generator in which the winding is placed between the two, carried on the rotor. Since the structure of the core is critical, there is no place for soft iron etc. in that rotor core; and it is also important to appreciate the geometric configuration of the field coils to see how these will drive the rotor, and act as the principal part of the inductive field.
I have NOT managed yet to make the rotor spin past 135 degrees for want of the switch I need to build or otherwise acquire -- which is why I'm asking questions here in as sensible and useful a fashion as I can. And if ever the contraption 'works', meaning that some discernible current, however small, is generated in the winding -- which I reiterate is exposed in its entirety to a changing magnetic field at all times (unlike conventional machines) --, you'll be the first to know. At no stage incidentally have I suggested that this is in any sense a 'greater than unity' device and wonder why people are forever suspicious of such intent in the face of unfamiliar notions. And it's an experimental apparatus, singular; wood is good enough for that single prototype.

Your suggestion of a stepper motor driver might be just what's required; and I wish you'd mentioned it earlier. As you realise, the rotor needs to spin in one direction continuously, and this requires that all the electromagnets [6 N, 6S] are switched on at all times, each set of 6 switching polarity every half-cycle of 180 degrees, but each set 90 degrees out of phase with the other. Bearing in mind then that this set-up would be akin to driving a bipolar permanent magnet stepper motor except that the electromagnets must be charged continuously -- not on/off etc. --, can you suggest a stepper motor driver that can be programmed to do that?

Can you clear up the question I asked you though, whether the driver output circuit and the H-Bridge are basically in parallel?
 
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