Corvis (temp bot name) rough ideas.

[Bacon Wizard]

It just seems a bit "over-engineered" ie...why do you need an inductor simply to bring in more voltage (which you could do with a simple remote switch)? As engineering apprentices at 16 we were given the train of thought that in most cases simplicity will equate into reliability.

That might be right. I'd just like to smooth the supply out after the result, and I don't want to treble the voltage at a third of the duty-cycle or third of the amperage, either. It seems to me that an inductor is useful.

[daveimi]

If you want to run 24V with bursts of 72V, surely it's as simple as using a remote switch to bring the other two packs in series with the circuit?

I understand you want bigger and badder, it's the DC - AC conversions and Inductor packs I don't see the point of. It's quite probably in my ignorance, but is there a benefit to using inductance and ac-dc conversion to achieve the step up in voltage?

[Max]

All you have to do is turn the supply on to charge caps, and turn it off again to discharge them. You don't even have to turn the DC off, just re-route it if it were really necessary. If that were considered AC, then anything binary in nature will need to be banned.

Ok that's fine, I thought you were converting it to AC and didn't want you to be caught out by the rules. Although I imagine this concerns the "loopholes" part of the rules so you should ask if it is acceptable before building and I would also ask the event organisers if they are happy to have a 200kg robot in their arena- there aren't any superheavyweights for a reason.

[Bacon Wizard]

Ok that's fine, I thought you were converting it to AC and didn't want you to be caught out by the rules. Although I imagine this concerns the "loopholes" part of the rules so you should ask if it is acceptable before building and I would also ask the event organisers if they are happy to have a 200kg robot in their arena- there aren't any superheavyweights for a reason.

It's a walker. double weight allowance. I think it's pretty much established that a 200K walker is ok, if it's within the regs.

It's not the weight of the robot that's a problem per-se I don't think, it's the power of weaponry and mass of flying bits against the arena wall. But yeah, EO always get the final say of course.

I bet the whole voltages thing is about fire safety more than anything, but I'm in the habit of asking these things, yeah.

[Bacon Wizard]

If you want to run 24V with bursts of 72V, surely it's as simple as using a remote switch to bring the other two packs in series with the circuit?

I understand you want bigger and badder, it's the DC - AC conversions and Inductor packs I don't see the point of. It's quite probably in my ignorance, but is there a benefit to using inductance and ac-dc conversion to achieve the step up in voltage?

Not using AC conversion.

But in answer to your question, the regs limit the number of battery cells that can be wired in-series. You can't get anything like 72v by doing that.

[daveimi]

Oh ok that's cool.

I wasn't trying to come across as an idiot and appear to be putting down your design, it was just trying to understand the reasoning for the inductors and so on

[Shakey]

DC-DC inductor boosting is fine just needs some careful thought. The tricky part is getting the circuit to handle the current needed. You can't get around the basic physics that a weapon using x amps at y voltage is after the inductor is going to demand 1/3Y and 3X before it. Also DC-DC boosting is prone to failing or overheating in high power setups. Just suggesting that you make sure that this setup will definitely be able to provide the power needed.

Sources: DC boosting is very common in coilgun making, spent my last few weeks researching it.

EDIT: The voltage limits are to do with regulations concerning what is low/high power equipment. I believe the 72V is the threshold. If there were robots using over 72V it would affect the event insurance or precautions needed to be taken I presume.

You can pretty much boost up to a few kV still with minimal fire risk.

[Bacon Wizard]

Forewarned is forearmed, cheers.