Tesla Model 3, 400V 500A 3-phase inverter, description and annotated images,
Earlier we were discussing, struggling how to best get the heat from SMT mounted DPak transistors onto a heatsink, likely one on the bottom of the PCB.
Images 6 to 9 shows Tesla's approach, with 24 GK026 ST SiC MOSFETs (they don't show up on ST's webpage).
Breeding resistors? Oh, I see, China.
Jeroen Belleman
Winfield Hill wrote in news: snipped-for-privacy@drn.newsguy.com:
It looks like a really bad design. Notice that they were too lame to encapsulate the HV section and only put little drips and drabs of RTV over specific areas. Likely with zero RTV primer applied.
That RTV stupidity alone is a failure mode waiting to happen and likely to happen... soon.
And those three tabs look like they can do 500A (maybe), but NONE of the rest of that little bitty circuit looks like it could churn a
100% duty cycle at those numbers. Of all the places to worry about weieght or heft. That thing should be a lot beefier. Just look at the stuff the kids at MIT makes for their robot competitions.Looked like a lot of the rest of the circuit could have problems too. Banks of resistors? All just so the guy could keep it all SMD? Not sure I agree with the minimalist, just barely makes the number design paradigm here. To me 400V 500A unit would be a lot bigger than that. I am skeptical.
Winfield Hill wrote in news: snipped-for-privacy@drn.newsguy.com:
0.2 MW?I am skeptical from the start.
Somebody moved a decimal too many places to the right somewhere.
100% duty cycle? That's only needed for what 3 to 7 seconds? Oh, wait, gotta double that for braking.
They label it 300kW. But 400*500 = 200kW. Divide by 750 watts/HP and take off 10%, get 240 HP. Hey, pretty impressive, but in the territory for these cars. The Bolt has similar numbers. According to Weber Auto, Chevy's electric motor was supposed to be the equal of the big engines and increasingly replace them in the full lineup.
Here's what I don't get. It looks like they have SiC modules bolted to something, with heat sinks on the other side in circulating coolant. The modules have gate-drive pins (and a drain pin to check for de-saturation?) sticking up, soldered into the PCB from underneath. I used that scheme on my AMP-70, but had PCB holes to tighten the mounting screws. See photos here, showing what I'm talking about.
To assemble it, you turn the board over and inset all the MOSFET leads. Then you screw the MOSFETs to the tapped heatsink holes, with the board still loosely in place. Finally you solder the pins, and can unscrew the FETs and remove the board for work.
But Tesla has no access holes in the PCB. How do they align 24 sets of MOSFET pins into the bottom of the PCB after they've mounted the MOSFETs?
the electronics looks IN accessible for repair
m
You must be joking. They'll just replace the whole assembly and toss the old.
Jeroen Belleman
Jeroen Belleman wrote in news:q709l7$1f75$1 @gioia.aioe.org:
One would think they would make it similar to the alternators of the '70s. They were fully serviceable on the most often failed parts... the rectifiers.
In ths case, I think they should have an integrated device for collecting braking force energy as well as the device for charging the batteries with that collected energy, as well as the electronics for feeding the motor loads. Banks of supercaps couls store up momentary braking juice and then deliver properly regulated charging voltages to the batteries in a 'batch mode' type thing.
The output block should be 100% serviceable on those elements which would fail most often.
The thow the whole assembly out and replace is for wristwatches, not high end motor driver modules.
His crap is looking like a tinker toy encapsulated in a high end, well designed Aluminum cast water jacket case. Wow... they now how to design a case.
They are violating the one-resistor policy.
Teslas seem to be fairly reliable, at least in the drive train.
torsdag den 21. marts 2019 kl. 14.41.58 UTC+1 skrev snipped-for-privacy@decadence.org:
why? it matches the specification 211kW/283hp and performance 0-60 in ~5sec of the car
it wouldn't do 0-60 in 5 second with 20kW
A surprisingly large number of components compared to VFDs with similar power ratings.
Just wondering how this inverter will survive in the tropics. The PCBs don't even appear to be coated.
On Mar 21, 2019, snipped-for-privacy@downunder.com wrote (in article):
In Kalifornia, we don?t need no coatings. (c;
Lasse Langwadt Christensen wrote in news:b3d8cae2- snipped-for-privacy@googlegroups.com:
I'd bet that I could make my bicycle do it.
snipped-for-privacy@downunder.com wrote in news: snipped-for-privacy@4ax.com:
One of the pics looked like it had UV clear cote encapsulant sealing it.
Looks like each MosFet has a square glue pad. Some type of theraml epoxy maybe. Probably used a jig to align everything.
Cheers
A VFD is only PFC and inverter
Tesla has PFC, DC/DC converter, Charger converter, Inverter (bidirectional due to breaking energy)
Looks ok to me
For a very high efficiency converter, you need to play tricks that violates easy assembly (most notably secondary side leakage induction minimization)
Cheers
Klaus
I'm surprised they didn't provide for easy removal of the board and SiC modules. It's easy to identify bad SiC FETs: most likely failures are drain-gate shorts. They could have used hex-head screws and provided small access holes for the hex driver.
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