How Are Platform Power Requirements Driving Designs for Modular Systems for Air and Ground Vehicles?

Good morning and welcome to today's military and aerospace electronics webinar.

How are platform power requirements driving designs for modular systems for air and ground vehicles?

This event is sponsored by Elma Electronic.

I am Jamie Whitney, senior editor of military and aerospace electronics with Endeavor Business Media.

To begin, let me explain how you can participate in today's presentation.

First, if you have any technical difficulties during today's session, please note them in the questions window, and our technical experts will help you out.

We recommend disabling any pop up blocking software or extensions in your browser as these can cause issues with the webinar player.

Additionally, we welcome your questions during today's event. We will answer as many questions as possible during the q and a session that will follow the main presentation.

But please feel free to send in your questions at any time. To do so, simply type your questions into the question window on the side of your screen and hit the Submit button.

Also, please be aware that today's session is being recorded and will be available on the military and aerospace electronics website within the next twenty four hours. You'll be notified by email when the archive is available.

Now I would like to introduce our speakers for today's discussion.

As director of engineering for Bellman Electronics, David Gash has twelve plus years of experience in power supply solutions for various industries, including embedded systems and motor control.

He's an active participant in open systems standards, including Vita and Sosa.

David holds a bachelor's and master's degrees in electrical engineering from Stony Brook University.

Ken Grove is director of embedded technologies for Elma Electronic.

He is responsible for driving the company's integrated platform solutions.

He is a highly respected technical expert in embedded computing, open system architectures, and a leading contributor to Vita standards and the SOWSA technical standard.

Ken holds a BSEE from Drexel University in Philadelphia.

Welcome, David and Ken. Please go ahead.

Thank you, Jamie.

Hello, everybody. My name is David Gash. And as Jamie said, I am director of engineering for a company called BEMO Electronics.

And today, we're gonna be talking to you about how the platform power requirements of the various, military platform are driving the design for modular systems and particularly focusing on both the air and ground vehicles.

So to start, the the each platform has its own unique form of power generation, whether it's a fighter jet, aircraft carrier, helicopter, or, tank or ground vehicle. And all of these have different, parameters for which, a system that is designed to operate or capabilities of the power generation, thermal and mechanical, requirements, thermal and mechanical, requirements.

And they all have different varying levels of the quality of their source.

Obviously, the bigger the the platform, the more room can be dedicated towards generating the power, and so that generally means cleaner power. Whereas the smaller platforms tend to have, worse power generation and then and thus need have more requirements.

So we're gonna be as I said, we're gonna be focusing on the both the vehicle power, which is defined by MIL Standard twelve seventy five, and the aircraft power, which is defined by Mil Standard seven zero four. And we're gonna be talking about them in generalities as well as some specific challenges that these standards, pose that, make developing systems, for these platforms a challenge.

So, as I previously said, you know, vehicle platforms is not always a constant power. Just like if you have your your power from your wall, you know, you like to say that it's, constant, but it varies a lot depending upon, what else is going on in the on the system. For example, you can have a large load that is turned on and off, which is creating either sags or spikes to your your line.

You could have, platform specific performance parameters such as perhaps needing to operate while turning over, combustion engine or transferring from one power source to another power source.

And these are different for every different platform because the way that the platforms generate electricity is different. For example, on a vehicle ground vehicle, you typically have a battery and an alternator that is used to generate, power. Whereas on an aircraft, you you are likely to have, some sort of auxiliary power unit or a generator built off of the the engines.

So for a lot of military systems, people want, you know, what they say what they call twenty eight volts in. And that twenty eight volts, even under normal conditions, is not always twenty eight volts or very, very likely to be. So this is kind of a snapshot of general, requirements for both Milstead and seven zero four, which is the standard that specifies basically the power that's on an on military aircrafts, and Milestone twelve seventy five, which is similar for vehicle power.

So you could see here that top line, steady state voltage. That basically means that it in that the, that the bus can be indefinitely between those two ranges. So you can see on an aircraft, it can be between twenty two and twenty nine. And on a vehicle, it can be between twenty and thirty three. So you can see right off the bat, the power on a airplane is different than the power on a ground vehicle even just in where it normally lies.

Beyond that, there's other finer details that are different.

For example, the ripple, is different based off of what platform it is and, as well as the transient voltage. So how how why can the voltage go temporarily?

On an aircraft, the latest versions of the standard, have it go up to fifty volts. And on the vehicle, they can go as high as a hundred. And the all all equipment needs to not to, not necessarily operate but not be damaged by any of these transients. So, looking at this, you can see that a a vehicle power, system has to be more operationally resilient than potentially one for an aircraft.

So on on this slide, you can see here the envelope for Milstern twelve seventy five. And on the right hand side, you can see kind of the, the the nominal range of twenty to thirty three. And then as you go, you can see the extremes of the the transient performance with the, the x axis being the time.

This is basically the description of, where where the white is, basically, is where you expect to be operating.

And where the gray is on the bottom, it's indicates that you may lose performance.

And on the gray on the top means you may damage the the power, the product.

Milestone twelve seventy five also has other various, requirements. One of them, which is probably the most has the most effect on system design, is the what they call the initial engagement cert and cranking search.

So, when you turn over your vehicle, the starter, which is an electric motor, has to pull lots of current to be able to turn over the the internal combustion engine. And as such, the voltage, of that battery, drain, sags quite a lot.

You could probably have noticed this in your vehicle at home if you try to turn over the engine and you can see the lights dim on the the dashboard or your radio turns off.

It's the same concept here.

And critical equipment on on the vehicle, must remain operational. And this poses a big challenge because, that voltage can go as low as twelve volts.

And, looking at this curve, you can see here that twelve volts can be present for a second.

As far as electrons are concerned, one second is a very long time. It it basically means you have to be able to operate as, for all intents and purposes, a steady state at that level.

This poses a very large challenge from the power systems perspective as the, the the current required to basically go down to twelve volts, the the current that you need to pull increases because for a power is equal to voltage times current. So for equivalent power level, the lower the voltage, the more current you have. This puts a lot more stress on the components and, the power supply in general, and, thus, it makes a much, makes a challenge, usually requiring derating of the product, for operation.

Milestone seven zero four is a little bit more of a less targeted standard because aircrafts have many different, power buses.

They're they could have twenty eight volts, two seventy volts, three phase AC, single phase AC, and there's, upwards of eight different power forms that are available on an aircraft. For the purposes of this conversation, we're just gonna talk about the twenty eight volts. And, similar to the twelve seventy five curve that we saw, we see the same kind of curve for the seven zero four twenty eight volt bus with the peak of fifty volts and the the trial of eighteen here. Again, if it operates above this line, it isn't expected to be, you you can't expect the product to necessarily survive.

Below this line, you would expect you can't expect it to be operating. And then in between, you would expect it to be this normal operating envelope.

Milestone o four does have a special, consideration that is unique to itself, which is, what is typically called hold up, but it's actually officially called power transfer in the standard. And, essentially, what that is is when you're on, when you're on the ground on an airplane, the ground station is gonna be providing you power for your electronic equipment. You'll have an umbilical that goes to, whatever, equipment you have on the side, and that will be used to power while you're on the ground. When you, are preparing to taxi and take off, you will transfer powers from that ground station onto the onboard APU, at which point that transfer takes a period of time. And it's usually characterized as being fifty milliseconds, and that's where the the the colloquial name for this as being fifty millisecond holdup comes from.

This, on the, this basically poses a challenge from a swap perspective because the energy that is required to basically operate your system during this transfer has to be held contained onboard. And in most cases, this is in the form of capacitors, and they're just a physical constraint that you have to have so much capacitance and so much energy storage devices on this product to on this platform to be able to provide the holdup that you need that it basically drives mostly the size and the weight of the product as you have to have extra elements that may not necessarily be needed if you didn't have to meet this requirement.

Here you can see, a what we what Bellman would call a hold up card, which is kind of a power conditioner, which accepts seven zero four power at the input and provides seven zero four power at the output, but it provides hold up, for that power. So you can see this teal line, and you can see here that while the dark blue is going to zero, the teal does not reach zero, thus allowing the back end system to continue to operate.

So how are these challenges being solved by MOSA?

So the VIDA, committee, VIDA sixty, VIDA sixty two dot o is a power a standard that defines a bunch of power modules or power supply cards.

These provide many different options for the user to be able to select and includes power supplies that have various different input power forms as well as power, power conditioners and energy storage modules that can help meet these, requirements. And whether that's a hold up card, as we discussed previously, or a transient for suppression device that might provide some protection over those, hundred volts or fifty volt transients or other types of modules in there. And this ecosystem, has developed with multiple vendors providing solutions.

And in a lot of cases, these, different solutions can be drop in replacements for each other because of the way that n c v s sixty two dot o is written.

This standard has also been leveraged by the SOST technical standard and is used in and is, leveraged by that and defined further inside of the SOST technical standard.

So as an example here, we have, two different products, what we call the VPX three hundred d IQI and the VPX five hundred m sorry, DW IQI.

These are products that are drop in replacements for each other, but, are targeted towards different platforms. So if you have a system for which you need to put it on an airplane, you could plug in the VPExtra eight hundred d I q I, and it will, provide all the all the enter all the needs that you need for that. But if you wanna take that system and put it on a vehicle, all you would need to do is unplug the five hundred DW and plug in the unplug the Ender d and plug in the five hundred DW, and you would get a power supply that meets the millstone twelve seventy five along with the cranking and initial engagement search specifications.

The one thing you will notice that, as we discussed, because of the need for going down so low, you do trade output power capacity for being able to do that. The the vehicle version is lower power because of that.

So, with that said, I'm gonna turn it over to Ken who's gonna then who's gonna discuss how to take these most of the solutions and integrate them into the system.

Thanks, Dave.

So, David's, in his introduction, gone over the different requirements that we have for the power supplies and vehicle applications versus aircraft applications. So I'm gonna speak to now how, what the system can some of the system considerations are when we're looking at applying power supplies that meet those specifications at the next higher level.

So as Dave mentioned, the power supplies are typically designed to v two sixty two, and this defines or or provides the definition for the power supply, including its size and how its, interface is defined between it and the rest of the system. So the picture to the right is a a chassis. And when we consider, building a system, we need some place to hold the cards that implement it and a package that's appropriate for mounting in the platform.

Then we also need to consider how we make the power supply and how we connect it into the system. So the, green section on the right side, top right, is called a backplane, and this is how we interface the cards together in the system, plugging them into slots. In this case, it's defined, through the OpenVPN standards.

The connector on the far right, the black one, is actually how we interface the power supply.

What's convenient about this is that power supplies are defined in a three u plug in, and we have a mating connector that plugs into the backplane. So the power supply is basically modular.

It's removable, and it's pluggable.

The chassis that we're showing is conduction cooled, meaning that the cards are designed for conduction cooling. So we have a channel or slot that the power supply plugs into and heat's transferred away from the power supply through the rails and then to the outside world.

So the good thing about this is the power supply's modular, and to connect it is all that one needs to do is, simply plug it into to the slot.

So other considerations, as David pointed out, would be, holdup and how that's implemented.

The holdup solution's usually implemented in a separate module, so we need to find a space for it in the chassis. And, in this case, we're showing the holdup module mounted on a plate that's in the front. The holdup modules can that, provide additional energy storage, for the system during, events, can be mounted fixed or they can be removable. So you can plug them into a slot and they can be removable just like the power supply or they can be fixed mount. They're available both ways.

So a benefit of following the v two sixty two standard and defining the the power supplies in a pluggable module format is that one solution or one physical implementation can be used to multiple platforms, this being aircraft or ground.

So, as Dave discussed, we've got some tradeoffs to consider, in the power supply design.

When we're considering the standards, vehicle standard twelve seventy five versus aircraft standards, we've got issues like, engagement or starting, which, pulls a lot of current at a lower voltage causing it to sag. What this causes us to do is look at how a power supply is designed internally because we've got the needs to operate at a a lower input voltage for a period of time driving more current. So what has to happen is that the power supply itself is beefed up. It's gotta be able to have heavier components because of the currents that it's handling in those conditions.

So this is not typical of all inputs. What this does is it puts pressure on the total amount of power that we can deliver from that power supply.

So it's reduced. What this is doing the the designer of the system is making them consider how do they get enough power from a power supply, into the system and consider that for a wider range supply, potentially, they'll have less of an output than they may have, say, for this MIL Standard seven zero four supplies Dave showed before. When we're looking at the wide range supplies, we might get about five hundred watts out of the supply. And when we're looking at the power supplies for MIL STD at seven zero four, we get around seven hundred or eight hundred watts.

Another consideration in the system implementation is something called chassis management.

Chassis management, when we're looking at SISO and CMOS systems, is a requirement. This is a two wire interface that connects the PECs, the boards that are in the system, to the other boards that are in the system along with now an intelligent power supply that must also be able to communicate on this intelligent platform management bus. But this allows the system manager or the chassis manager to do is communicate with the power supply, get information from it to see that it's okay, also be able to send certain control signals on it and actually be able to, turn it on and off or inhibit its operation.

Use of the pluggable supplies aligned with V2-sixty two is something we've talked about, whereas V2-sixty two is actually the standard that defines how the power supply is implemented, its size and, its characteristics and the signals and the voltage rails that are implemented in that.

One other thing that we might need to consider or two would be scaling. For instance, if one supply doesn't supply enough power for you, then you may actually have to include more than one, which is allowed and doable.

And another point would be if you're looking to to improve your overall, let's say, availability or reliability, you have the option to do something called n plus one, which is to replicate a power supply, not use more than one supply supplies as far as power, and then have another one that's sort of a standby unit that will take over in case one of the two set power supplies, fails. So these considerations are built into the designs of the power supplies to allow them to be able to be scaled or allow them to be able to be used in n plus one configurations.

So digging down a little bit deeper, what does v two sixty two do for us, and what what are some of the characteristics of the of the power supplies themselves when we build them into a power system?

When we look at, the SIRS and CMOS specifications, they're now specifying that power supply should be twelve volt centric.

What this means is that the rail scheme has changed now, and the newer go forward strategy is to have a two rail implementation, providing twelve volts as the primary and then three point three aux. Prior, power supplies had multiple rails, plus five, plus three, plus minus twelve, etcetera, and that's called the legacy implementation.

Both of those implementations still exist, but when one designs for a current system around the twelve volt centric supply, you have to realize that, in fact, that supply now provides two rails where if you were going to mix these supplies, you have to think about, that there's two different definitions for them today. So there's a, a legacy definition and a twelve volt definition. So, typically, we'd use all of one type in a system where the power supplies are twelve volt and three point three.

When we look at what VDA62 and the new definition has done, there's some other features that have been added. One is this MVMO signal. It's been added as a requirement which, protects the, information that's stored in memory devices and makes it, write protected.

And then, we've also seen considerations for the intelligent platform management bus for smart power supplies to add intelligence to the supplies.

So what's been removed is the plus and minus twelve volt rail and the, or the plus and plus twelve and minus twelve, rails are removed in it for one common supply rail of twelve volts, where we used to have, five, twelve, minus twelve, and three point three and three point three aux.

So another consideration of the power supply are share lines that are used for current, current sharing between the lines. And, typically, manufacturers there's these lines that are defined, and manufacturers develop a a strategy to make their power supply zero current so that you can scale multiple power supplies, in a power system.

So what you end up with is a more, let's say, simplistic approach and a two rail design, intelligence being added through v dif forty six dot eleven, and then the NVMRO signal added for write protect.

And and as I said before, one needs to be thinking that you need to be careful you don't mix, the two, like, types of plot supplies that might be out in the market. If you need multiple rails, they're still available. If you want twelve volt centric, that's a specific implementation under the VITA sixty two specification.

So looking and taking another look at how we mount these, look closer view here of the backplane, mounted inside the chassis, and we can see the v two sixty two connector. And to the right, what we see is how that power supply looks when it's bounded into the conduction slot and plugged in and mated, with a connector on the backlink. The beauty of that is it's simple, it's easy to replace, easy to insert.

There's no extra wires that you have to worry about because this is a pluggable interface that's designed to carry the current. That's another consideration in the backplane that we have high currents coming out of the, pins on the v two sixty two connector, and we need to have appropriate power plane designed designs to transfer the power down through the backplane to each one of the slots that are in it where each card in that, backlink is taking power from the backlink provided by the power supply to power the card.

So the beauty of following a standard like v two sixty two and, the benefit would be that you can have one type of supply or supply, let's say, building blocks that are allowed, the power supply itself, the hold up module, etcetera, and be able to use them in different types of chassis. So the chassis size and envelope may differ for the application. In this case, what we're showing on the left is a supply a chassis that's designed for vehicle application designed to the save specification where it's got an isolation plate and, it's mounted on that plate in a specific envelope.

If we were looking at a a chassis for an aircraft application, in this case on the right, it can use the same kinds of supplies that can be used in the vehicle application on the left.

So you sort of have one approach for the way that the power supplies are packaged and, the way that the interfaces are defined. And we can use them and then in different types of chassis, in this case, an ATR for the aircraft application that mounts differently in a different space envelope because of what the platform requires.

So it gives us a family of common building blocks, that makes it easier to produce power systems that can align with various applications that are out there, with one approach.

So where we end up is a well defined, implementation, this two rail design with three point three aux with intelligence and the ability to share, share, current to be able to scale. And we implement v to six forty six dot eleven or the chassis management interface, for systems management so that we have some way to look at these power supplies for reporting and for control.

So that brings us to the end. So just taking a, wrapping up here and looking at what we've talked about today.

Power requirements vary, as we discussed, on depending on the platform and the application. So for aircraft, requirements are driven by MIL STD seven zero four and for vehicles MIL STD twelve seventy five.

As, Dave showed in his charts and described that the input quality varies depending on the platform and the range of the transients also vary. And then we have various, things to consider such as switchover interruption in aircrafts when you're transferring from ground power to aircraft power. And then in the vehicles, a different type of requirement that is driven by the starting engagement, where we have a heavy current demand on the vehicle battery system pulling down the voltage, which makes us have to consider operating at much, wider ranges on the, input voltage to the supplies.

So things we need to make sure we cover is that wide input voltage range in both applications, a little different for each one. And then the whole whether a holdup system is necessary in vehicles, it typically is. And how we implement that. In the case of the vehicle design, there's not enough room in the power supply to do it, to package the voltage. So we're doing it with something called a holdup module, which is an additional component that's considered in the power supply implementation.

So, VU-sixty two provides the standard for the modular power supply designs in the form factor. And as discussed, this can be used in both aircraft applications and chassis designed for aircraft as well as in vehicle applications.

COSA has sort of advanced the power scheme and moved those recommendations or requirements that are in COSA to VITA where they've been incorporated in VIDA sixty two, which gives a newer twelve volt centric approach to the power supplies and also options for intelligence included through forty six point one one.

Then lastly, the VITA sixty two family of pluggable supplies and holdup modules provide an off the shelf implementation that makes it a little easier for system, builders to take products that are predefined by the ecosystem to apply to implement the power supply systems that are required, for various applications.

So with that, I'll turn it back to Jamie for Q and A.

Thank you.

Alright. Thank you so much, Ken and David.

A few of you have already submitted questions, so we're gonna jump right in.

As a reminder, if you would like to submit a question, type your question into the question window on the side of your screen and hit the submit button.

I would also like to note that material from today's presentation, including the slides used by Ken and David, are available for download, And today's presentation will be available on the military and aerospace electronics website within the next twenty four hours.

Okay. And our first question, what if my system does not require operation during vehicle startup or power transfer?

David?

So one thing that's good about this whole, modular approach is that if you don't need something, you just don't need to use it. So for example, if you're deploying a system on an aircraft, but you don't have a requirement that your system operates through the power transfer, you could just not use the holdup module, and, the power supply portion of that will handle everything else. So while you may not need to use the power transfer, but you, operate during that power transfer, and therefore not need all that energy storage, you will still need to operate through all those transients that were shown in the the presentation.

So you still you can't get away with, you know, a a very simple power supply. You still need something that's somewhat ruggedized, but you you don't need to have pay the, the swap penalty for having all that energy stored up. On the opposite side for the vehicle, for the, startup initial engagement surge and cranking, Again, if you don't need to operate when the voltage drops below eighteen volts, you can then just use a a power supply that has that does not have the low wide range input rate, which then probably means that you can use a higher power product. And, again, the beauty of this modular system is that it's you unplug one, and you plug in another, and you're you're good to go.

Great. Thank you. And, Ken, a question for you.

Can I combine power supply plugins to increase the overall system power available?

Yes.

The design considers that they could be scaled, so you can you can plug in say you need the power of two supplies. You know, if you're in the wide range, you might need a thousand watts, and you could do do that by combining two. You can actually use more than two if you need you you need more than two. So yes.

Thank you. And what about surface ship and submarine applications? David, do you have any thoughts on that?

So, yeah, this presentation is mainly focused on Milstaron seven zero four and Milstaron twelve seventy five, which are the the the specs for aircraft and vehicle respectively. There is actually one for, naval applications, which is Milstaron thirteen ninety nine. That one, is largely similar in its content, although the power forms on a ship don't necessarily align completely with the ones that, like they do, for example, comparing the twenty volts between a vehicle and a plane.

As such, equipment that goes on, an able ship is typically a little bit more, is is not necessarily directly comparable.

And, also, because it because typically the ships have more space, not only is the power better behaved, but the equipment itself can be physically larger, to meet the same requirements.

Got it. So so Milstar and thirteen ninety nine would be the standard that you would look at, and they would contain a lot of the same information that you that we discussed here today.

Oh, thank you. And, Ken, can the power supplies be monitored by a chassis manager?

Yeah.

So as the power supplies have evolved, not all power supplies prior had this capability. It wasn't really deemed necessary till more recently. But now for intelligence, the power supply has to have, like, a small microprocessor in it to be able to respond to commands that have to do with monitoring that would be coming from a chassis manager that's mounted somewhere in the system. That chassis manager would be communicating with the PICs, the other cards in the system, as well as the power supply. He'd be looking for things like, nominal voltage rail, compliance that that the power supply is within tolerance.

And it can also do things like, communicate to the power supply and, give it a command to, maybe turn itself off or turn itself back on, for instance.

Alright. Well, gentlemen, thank you so much for your time and your expertise.

That concludes today's presentation.

On behalf of Military and Aerospace Electronics, I would like to thank our speakers, Helma Electronics for sponsoring today's webinar, and of course, all of you for joining. Have a great rest of the day.

Thank you.

Thank you. Have a good day.

‍