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Tesla shares 48V architecture with other automakers

electrek.co

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Re: Tesla shares 48V architecture with other automakers

#331

Post by Moto7451 »

sbierwagen wrote: post #238
Moto7451 wrote: post #189

Audi also has a 48v architecture in use for mild hybrids like my SQ5. This is an older article but explains it well https://www.greencarcongress.com/2017/06/20170602-audi.html My 2021 is fully 48v except for an inverter for necessary 12v circuits (like cigarette outlets and the jumper pins) and a small motorcycle battery that is used for minimal 12v functionality. The mild hybrid battery is under the rear seats and s…

>and the jumper pins It can be started through the converter? That takes something like a hundred amps. It must be pretty beefy.

In the case of my Audi, the starter motor is 48v so the 12v system charges the 48v system enough to start.

In EVs the 12v system is used to power a contactor that connects the EV battery to the drive system. That’s the clicking sound you hear on power on and power off and another contactor can be heard clicking during charging.

Re: Tesla shares 48V architecture with other automakers

#332

Post by bsder »

horacemorace wrote: post #280
klysm wrote: post #278

Earlier quoted context omitted.

Why is it inherently noisier?

Faster slew rate for all switch supplies in the system. Nothing directly runs 48v.

Not true.

Your motors and actuators operate directly on 48V (in fact, most actuators would prefer a higher voltage like 96V). That's really significant.

Microelectronics is effectively a "don't care" since everything is behind a regulator or a PHY.

Yeah, 48V tolerant switching regulators are going to be a bit more expensive until the volume gets rolling, but that problem solves itself while ethernet and CAN PHY chips are already 48V tolerant.

Re: Tesla shares 48V architecture with other automakers

#333

Post by Turskarama »

masklinn wrote: post #326
Turskarama wrote: post #264

Earlier quoted context omitted.

Two motors is great and all, but that only provides motor redundancy and won't help if something happens to the electrical system. Planes are fly by wire but that's because they literally have to be, no amount of gym time will let you move the rudder on a 737 by hand.

The 737 is not fly by wire.

Ok fair enough, it is hydraulic assisted instead but for the point I'm trying to make it's essentially the same thing in so far as it requires power.

Re: Tesla shares 48V architecture with other automakers

#334

Post by Turskarama »

Moto7451 wrote: post #324
Turskarama wrote: post #218

Earlier quoted context omitted.

They're getting mixed up, the 400-800V systems are _only_ for the motors, everything else in the car still uses low voltage. In fact, afaik every single electric car has two separate systems. There's a high voltage system (the main battery and motor(s)) and the low voltage (almost always 12v) system, usually with a traditional lead-acid 12v battery that is charged via a DC-DC converter connected to the high voltage b…

I’m speaking about the power planes. What they drive is irrelevant from the standpoint that higher voltage systems create safety issues that lower voltage systems do not have. No one is going to be ok with “occasionally being shocked by 48v” or “occasionally seeing arcing in their car from a high voltage system.” Running 48v to a radio is not an engineering marvel. Running it safely and reliably in an automotive envi…

I feel like you're mixing up points now, running 48V is fine _because_ the voltage is low enough that it's unlikely to kill anyone if you mess it up. The 400V system in the meantime has a lot more care taken and limiting the systems it works on to ONLY high power systems lessens the number of things that can go wrong.

Re: Tesla shares 48V architecture with other automakers

#335

Post by jdewerd »

accrual wrote: post #310
1970-01-01 wrote: post #192

Earlier quoted context omitted.

>potentially improves overall electrical efficiency Looks like he understood it the entire time :)

I wasn't sure, so I asked: > Higher voltage systems experience lower power losses over the same distance compared to lower voltage systems. This is due to the fact that power loss in a conductor is proportional to the square of the current. By using higher voltage, you can transmit the same amount of power with less current, reducing resistive losses in the wires.

12 Volts is 12 Watts per Amp.

48 Volts is 48 Watts per Amp.

Re: Tesla shares 48V architecture with other automakers

#336

Post by imp0cat »

panick21_ wrote: post #72
bryanlarsen wrote: post #67

Earlier quoted context omitted.

It'd be cheaper to delete the 12V bus entirely and add 48V -> 12V converters in front of legacy components, even if they needed several dozen of those converters.

I expect Tesla to still have a few components like that in the car.

Isn't that the point of the article though? That they run everything on 48V?

Re: Tesla shares 48V architecture with other automakers

#337

Post by londons_explore »

KaiserPro wrote: post #104
londons_explore wrote: post #21

Earlier quoted context omitted.

Most MOSFETS are 50 volt rated. 50 volts is a sweet spot for switching the most powerful load with the smallest and cheapest switch.

if you're switching 48v, you'd want a mosfet rated for way more than 50v. On a car you'd want 200% headroom at least.

With totally uncontrolled bus capacitance and inductance, sure.

But when you're using the same bus for Comms you need to have control of high frequency spikes, and low frequency spikes are easily handled by a bidirectional DC/DC. Therefore I could imagine peak to peak ripple on this bus to never exceed 1 volt.

Re: Tesla shares 48V architecture with other automakers

#338

Post by jdewerd »

DannyBee wrote: post #272
mmaunder wrote: post #246

Many comments here seem to be confusing the accessories circuit voltage with the electrical vehicle motor and drive system. The vehicle motors have a combined power output of 450KW which requires a high voltage 800V system or the wiring would be so heavy it would not be feasible. This spec appears to be the accessories circuit with Tesla pushing for a new 48V standard. That’s super smart because it immediately means…

48V has been considered for automotive for decades. The problem was not know how. It simply has never been worth it before to retool things in practice. It's also electrically a lot more noisy. The limit of what is considered low volt is like 60v or something.

It was never worth it to retool for decades?

Or was there a pathological lock-in between suppliers and manufacturers that prevented even the most obvious innovations from happening if they required any amount of coordination?

Re: Tesla shares 48V architecture with other automakers

#339

Post by hulitu »

mmaunder wrote: post #246

Many comments here seem to be confusing the accessories circuit voltage with the electrical vehicle motor and drive system. The vehicle motors have a combined power output of 450KW which requires a high voltage 800V system or the wiring would be so heavy it would not be feasible. This spec appears to be the accessories circuit with Tesla pushing for a new 48V standard. That’s super smart because it immediately means…

> Tesla pushing for a new 48V standard. That’s super smart

48V is a dangerous voltage. Better not touch any wire.

Re: Tesla shares 48V architecture with other automakers

#340

Post by kelnos »

bsza wrote: post #217
jmrm wrote: post #141

>48V architecture also potentially improves overall electrical efficiency for reasons that I am not sufficiently qualified to explain beyond a kindergarten level This is double bad in a green energy and EV website: On one hand, they admit they don't now why that happens, but on the other hand, they also didn't research just a bit more on that, and that's bad journalism. Most of the comment threads in this HN post are…

> they admit they don't now why that happens No, they said “not sufficiently qualified to explain”. Which is not the same as not knowing, given that the same phenomenon can be explained on a lot of different levels depending on when you get tired of asking “why?” - see this video of Richard Feynman “explaining” magnets: https://m.youtube.com/watch?v=MO0r930Sn_8

To me that difference doesn't really matter. At the very least they should have educated themselves, and then provided links to resources to allow people to understand if they didn't feel comfortable explaining it directly.
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