FSAE and EPA Regulation

[coleasterling]

I don't mean to get too far off the topic, but ~300V has been pretty normal for hybrids. An interesting note is that many of them use boost converters to up battery voltage to the inverter. The older Prius boost converter takes voltage from ~200V to ~500V. I believe it was rated for 20kW? The Lexus RX450h ups that to boost to 650V for their rear diff motor.

I don't have much of an opinion as to whether higher voltages should be allowed or not, although I do see some extra safety concerns. What I would really like to know is why European teams feel the need to run such high voltages, anyway. I would understand if teams were using salvage EV motors that were designed for 500V+, but teams are getting custom motors, anyway. Torque density, assuming the same stator and rotor configuration, is directly related to copper fill and that's (probably?) not significantly changing between winds. Heavier cables?

[Swiftus]

@Julian - The European teams are certainly further ahead than the rest of the world. But thats what you get when your have manufacturers willing to sponsor 4x€10K for motors + 4x€YK for the controllers + €10K for the battery pack. That probably approaches €75K and you haven't put them drivetrain into a chassis yet.

But! If the electric competition were closer to what companies in the US are actually using in their vehicles, I think it would be easier to gain sponsorship of the expensive stuff for teams in the newly EPA-regulated world of motorsports. Maybe once the Gigafactory from Tesla comes online they might be willing to become a title sponsor of the competition and give everyone cells. That would equivalent to what, 4 Models Ss? I know they are still losing money, but it might be a good investment.

@coleasterling - I didn't know about the boost converters - good to know! I just read the spec sheets of all of the car's battery packs to see their nominal voltage. I think that argument is still valid but the voltage converters still wouldn't be legal under the current rules.

Higher voltages do a lot of things that benefit electric motors... which are not at all my specialty but I'll give the summary a go. The TLDR is power equals Torque * rotations and higher voltages let you stick in more power in a system to get out more rotations. Gear that to give you more torque and you're in business. Additionally, race cars need to be light. P = V^2/R, so if you want to shove the same amount of power into a motor winding, a 12V motor would need wires with 100 times less resistance than a 144V system. That's additional weight to handle the same power output. There are certainly diminishing returns when you go higher and higher in rpms because of emf etc, but I think the crossover point for efficiency with current tech still points to higher voltages than 300V being ideal, which must be why ever car manufacturer has packs at a higher voltage.

[nat45928]

I am in agreement on the reasons for the voltage limit in the US. Speaking as a US team, we would get whipped by anyone from the top 10 in Europe. We just have not had the time to create solid cars and have not been able to improve on performance yet.

Even with that established, I am not sure it was a good idea to impose the limit instead of outlawing the European teams IF that was actually the end goal. The electric teams over here have now bought and designed systems to work with 300V, if they suddenly bump it to 600V now tools and electrical devices like chargers may have to be repurchased. I personally would have rather seen the limit set at 400V or 600V to help encourage different powertrain designs out of the gate and try to accelerate us to the European level of performance. To go along with this most systems you can purchase, like a new team would, are designed for lowerish voltages or above 300V. You end up with systems that are under performing and have more performance left that you cannot use with the rules as they are(extremely frustrating). It's a major hindrance right now.

To everyone says to have Chevy or Tesla donate cells: Remember the accumulators in these cars are VERY custom. A pack built by a big name that is already in production for a consumer vehicle wont be able to compete with a solid design from a team. The cell donations would be a huge help though. As long as the teams can package them.

@Jay you're on the right track. The high voltages let us use less current which translates to lighter components and more efficient designs. Comp limits the power used and the voltage used, with that you can easily figure out the current needed to apply max power at competition. Also remember your battery voltage will drop as power is drawn and the pack empties so that increases currents if you want the same power (this is why some EVs slow down as endurance finishes). It all ends in high currents which require special, heavy and hard to find parts. There's a reason Formula E uses ~1000V system: it's light and powerful.

I personally cannot wait for that voltage limit to be lifted. In the mean time though the US is a pretty level field which should be interesting this year. If the EPA regulations actually hit we are going to see a HUGE transition in the US, they will wreck the US competitions.

[coleasterling]

I'm not sure I agree with that line of thought, at least without seeing the math. Some things are simple like cables. Yes, they have to be bigger, that's obvious. How much weight does that actually add?

Look at the accumulator to start. For a given pack capacity using the same cell, assuming similar cooling efficiencies, heat wasted in the cells is going to be approximately equal in either low or high voltage configurations. How good are your cell to cell connections? Take a very low voltage system, let's say 100V. That's around ~24 series cells vs. ~140 for 600V. You have around the same number of total connections, but far fewer series cells to contribute to the IR, with better current sharing for more parallel cells. Total pack resistance is easy to drastically increase from cell connections that are sub-par.

On the motor side: For a given stator and rotor configuration, torque is going to be equal, neglecting difference in copper fill. You probably would gain some torque with a higher voltage wind since copper fill would be slightly better with more turns of smaller diameter wire, but is it significant?

I don't know enough about the inverter design to make any comments on it. I'd love to hear about why higher voltages helps/hurts inverter efficiencies, though!

[JT A.]

If the reason for the 300V limit really is to keep the Europeans out so they don't beat up on us, I would have to say that is a very "un-American" attitude, for lack of a better word. The best way to speed up progress is better competition, is it not? It may also get US industries to kick up their support for American teams. Imagine if we had a competition in the US where American teams and European FSE teams competed under the same rules. What would Ford, GM, and Tesla think when they saw the results? Probably something to the effect of "Shit, we have to recruit engineers from these teams that are DNF'ing 75% of the events, while BMW and Mercedes are getting the kids from Delft, Stuttgart, Munich, & AMZ". If they want a better pool of engineers to hire from, they need to help more Universities get teams started (the cost is a major barrier to starting an Electric team) and get more students involved with internships / technical partnerships to help our students catch up.

[Swiftus]

I'll second what JT A. has to say. We know this competition was created to get student engineers experience working in larger groups on difficult and long term projects that have a tangible deliverable - something sorely missing in most University systems. And use of 'motorsport' and 'racing' would act as a draw to instigate more involvement and harder work out of the students. We all get competitive so why not use that to teach us some useful skills?

But many of the companies sponsoring and recruiting out of these events want to not only see students learning to work in a more real-world environment solving difficult problems, but they want students learning those lessons with the technology they use or produce. Thats a huge reason for sponsorship. When you have 2 applicants for a job with similar skill and experience levels, but one has worked in modern EFI and one has worked in modern EMI (what is a punny way to say electric powertrain?) and you are a company like Tesla, you'll hire the person who knows more about EMI since they can start making you money sooner.

It will be interesting to see how the US FSAE competitions are affected by these potential EPA regulations. Will there be an 'educational' addendum so it does not apply? Will the competition have to sniff the emissions of the cars? Scrut, Tilt, Sound, Sniff, and Stop might be the new order of technical inspections? Could be interesting.

Maybe if the electric car rules were loosed up the largest companies in the world might be interested in sponsoring the FS competitions? Google and Apple are hiring automotive engineers.

[Kevin Hayward]

The costs for competitive EV cars are high enough to destabilise the competition if there was no petrol option. Unless some sort of reasonable cost restriction is enabled, such as spec or control batteries (or many other ideas) the EV comp will remain the playground of the minority. Assuming 600 teams 75k per team for a powertrain is over 45 million Euro. The equivalent for a $10k petrol powertrain would be in the order of 6 million Euro.

I would also hope that everyone here is aware that 60kW electric is significantly better than what any decent petrol car can produce.

The current top end EV competition is awesome. In many ways Formula Student is leading the larger automotive world. However if it becomes the only option then costs need to come down a lot. I would hope that these over-reaching EPA regulations do not cause such a thing to happen.

Differences between regulations in different countries is not great though, and serious moves should be made to bring them into line. This might mean limiting the performance of the Euro's (while reducing cost) and bringing up the US teams. It is worth noting that the rules were changed early and dramatically in FSAE to limit vehicle powertrain performance. As good as petrol FSAE vehicles are I am not aware of any world records they could hold, unlike the EV acceleration show-down.

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US teams should make their thoughts known to their local representatives with well reasoned arguments. FSAE is a great training ground for future community leaders, and maybe letting someone else deal with the problem might impact you more than you would want.

Kev

[Claude Rouelle]

Doctor Hayward,

Stop whining (for once) and start winning. The money is there, even more in Australia: you just do not know how to find it. Think outside the box.

Claude

[jd74914]

Wow. Talk about a slap in the face comment for all those hardworking, clever, teams which have not found the magical sponsor unicorn.

After having participated in FSAE in the US for 9 years and personally secured many unique (read: non-automotive) sponsors, I really cannot even fathom how certain schools could come up with that amount of specialty funding (in-kind or monetary).

As far as I've seen, you really need a very special type of university support to do that. Around here most companies with heavy purses would rather sponsor graduate research. The same is true of high-tech companies (batteries, etc.). Without some champion pushing funding away from graduate research and onto undergraduate projects like FSAE I really do not see how funding levels like this are possible. Perhaps there are differences in Europe or other parts of the USA, but these are my observations from living/studying/working in the aerospace belt.

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On a separate note, I totally agree with Dr. Hayward's post. I would love to participate in FSE; the level of controls tuning really brings performance to the next level. Additionally, I think it allows better integration of electrical and software disciplines which seems to be lacking in combustion competitions. My working experience has been that these disciplines could use practical, hand-on experience even more than the ME-types.

[Kevin Hayward]

Doctor Hayward,

Stop whining (for once) and start winning. The money is there, even more in Australia: you just do not know how to find it. Think outside the box.

Claude

Claude,

I am not sure what was whining in my post. My issue is largely about what should be spent on these cars rather than what can be spent. Building a new car every year is an inherently wasteful exercise, and I have concerns about how much should be spent on these cars each year. My desire is to see as many students run through this program as practically possible. An increase in cost (and undue difficulties) make this less likely to happen.

If we take your view that every team should be gathering sponsorship at the level achieved by some teams (lets say $200k) that works out at $120 million per year for 600 teams. Add to that the costs absorbed by Universities and we would be likely above $200 million per year or more to run this competition. My objection to that amount of money spent on this competition is both moral and economical.

Morally as it represents a large sum of money that can be used elsewhere for more benefit to humanity. Economically, because it does not need to cost that much to achieve the desired educational outcomes.

On a related note a good friend of mine has just completed his PhD at John Hopkins University dealing with Global health issues. During the process he had some involvement with the Bill & Melinda Gates Foundation. An interesting point he makes regards how much money is spent on individuals in Western Health systems vs what is spent in third world countries. The cost of improving quality and length of life for a few could save the lives of many. There is nothing inherently wrong with the former, but the disparity is obscene.

I think the same is true of budgets in FSAE. Ultimately this competition is for the educational benefit of the next generation of engineers. Competition helps this as they enter a highly competitive industry. However as a program it should make economic sense. If the same outcome can be met by lower costs (both dollars and time) then it is silly not to do so.

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For the record I will say that I have been involved with two teams that would have been considered well funded by most teams. Both have been successful, which you are well aware of, hence my confusion about your exhortation to win rather than whine. We are currently in a position that if we wished to push for the extreme budgets required to be a top level EV team we almost certainly could. Although the extra funds would not improve the educational benefit proportionally and doing so would sideline funds from some programs that offer greater benefits to society.

I will admit that arguments about trying to reduce wealth disparity and caring for the wider population are somewhat socialist in nature. For that feel free to label me as a Formula Student socialist. Our difference of opinion on this matter may be as much political as anything else. Maybe I am the Bernie Sanders to your Trump. While you perceive my attempts to encourage inclusion and accessibility as being whining you should note that I see your constant calls for teams to stop being lazy and raise more money as a more destructive form of whining.

Kev