Endless Sphere

My vesc used discrete drivers and amplifier.It's cheap and stable. That's really neat and but has jack all to do with the original question, why is the drv8302 "not good"? Personally I use a TD350E in several designs up to around 25kW, it's old, low cost and very robust (Miller clamp, negative gate...

I noticed that current drawn affected that magnitude of the spikes more than anything else. This makes sense being that the spike is a reaction to parasitic inductance which in turns increases in severity when there is more current involved. That is expected, but take a look at what happens when yo...

TEK0000.JPG Vsupply = 50.4V, I Motor = 46A continuous So I did a test at 50.4V with the motor under load. I picked up spikes of 61.6V under these conditions. Note that I could not use low-induction/low-noise measurement techniques as I did before for this test. I estimate at least 3V are attributed...

I'm using 10ohm resistors right now for the gates but maybe i'll try higher. I figured I would try and keep the rise/fall time combined under 1% of the switching period. This was some guidance given to me earlier in this thread. Not sure why 1% was suggested for this application, but typically you ...

You could reduce your ringing and possibly the need for snubbers by slowing down your switch off time. Looks like you are switching <100ns and you really don't need to. A good practice is to start around 800ns and start reducing the gate resistor from there. You should only switch as fast as you nee...

The conduction losses are the primary source of heat and only depend on current. Switching losses will go up with voltage. Overall, you won't see much change with higher voltage unless your switching times are too slow. I^2*R loses are dominant at high duty cycle, but at low DC Vds (diode) loses do...

10cm is not an issue for gate drive as long as it is over the proper ground plane (not possible on current design). Another possible compromise is to use twisted pair for your gate drive and eliminate the traces all together. The twisted pair will be much less likely to experience ringing. It also h...

One thing to keep in mind if you do not try to cancel these fields is you will become an intentional radiator. It doesn't look like it would take much to include a overlapping bus design while keeping that same style layout. Caps would most likely need to go on a carrier board with mechanical connec...

When I read about how they heat stuff I started wondering if they warm up the IGBTs to get them into their positive temp coefficient operating area. Something I've thought about doing previously when I finally jump to paralleling IGBTs vs MOSFETs.

No leboski your numbers are overly optimistic. Truth is you forgot the sag... Likely a 100v battery will sag to 90v under load. Also you will never get a 100v fet to survive at its limits with a 100v battery. The numbers for this would be 84v absolute max fully charged and that will sag to ~75v und...

They turn on and off with RF level speeds. This sounds like a nice idea, but makes them a bit of a challenge to control in practice. I went to an IEEE presentation on High Electron Mobility Transistors (GaN) devices a while back. After the presentation I was speaking with one of the people that doe...

The inertia run issue was most likely due to the dyno control loop and the your motor drive control loop finding an unfortunate resonance with each other. I wouldn't be surprised if your motor drive can respond much faster to load changes than a dyno typically used for ICE cars (it might not have en...

Are you on bias play tires "slicks" or radials? Curious as a drag radial would also give you a little more MPH. Traction is all about suspension setup, read up on what the fast FWD guys are doing and adapt it to your setup.

When you get your 60's down the MPH will come up as well since they are really bad right now. It has really good MPH already which is what really shows the power (i've seen several 13 sec 130MPH passes on Supra's and Civics).

Congrats!

Had to convert the part of the chip dealing with impedances to floating point (hand-made floating point as the chip has no hardware floating point). So far it has added 1200 lines of (assembly) code, I expect to need another few 100. Rom is at 94% full now... Are you going to port the code to a pro...

I have a modded 72150 sabvoton that has been unlocked to do 200A. I was wondering if there is a way to do slide regen and brake/button regan. that way I would have two levels of regen. One to slowly stop me and another the stop me much faster. P.S. aliexpress has my modded controller for $275. Tota...

How are you making the DC link capacitor connection to the copper bus and the power devices? I've always found this to be somewhat challenging. I have proper soldering tools that allow me to solder to thick copper bus, but this technique does not seem good for production. I'm interested to see what ...

That is funny right there. I wonder if the marketing department reviewed the datasheet and modified a few things to improve sales. Reminds me of one of my favorite jokes: “Milk production at a dairy farm was low, so a farmer wrote to the local university to ask for help. A multidisciplinary team of ...

marcos wrote: Vishay sells an equally magic 2512 6W* resistor.

* = 6W rating only valid on 0 ohm values

Since resistor inductance and wattage are possible issues, why not place 3 in parallel? Populate them all so the inductance drops and wattage dissipation increases. I like the 2512 footprint myself for its large surface area (thermal management). Of course this depends on space available, but the bo...

Lockout = preventing the adjacent side from tuning on if one side is active, i.e. when the high side is active, the low side is locked out from turning on. Not sure why you need the logic gates myself or how they would interfere with the differential signal, but personally I would leave the driver c...

Marcos, I believe the reason for the external circuitry is to address a fault before it occurs. It seems more relevant to a design that uses separate High/Low gate drives vs one that has them both integrated into a single chip that has a lockout type function. Highhopes also uses that input techniqu...

not sure what you mean. we program for 21kHz instead of 20 kHz. or 18kHz instead of 20khz. 18, 21 .. both evenly divisible by 3. so your question is will the processor be stressed if it tries to generate a 21kHz frame rate as compared to a 20kHz. or 18khz as compared to 20khz. so here we are talkin...

HighHopes wrote: you mean 21kHz. keep the switching frequency as a value evenly divisible by 3 and this will magic out some harmonics

In order to do this, wouldn't the PWM need to be generated with 1Hz accuracy? That could be asking a lot from the controller.

Oh, okay okay, I'll keep that in mind. Battery pack is not laid out yet. To avoid what Njay is referencing (great point Njay!) you must keep the batt to controller leads as short as possible (reduces stray L) minimize their loop area. Inductance + loop area = the enemy, at least from battery to con...