Search found 831 matches

by Njay
Mar 31 2015 7:28pm
Forum: Motor Technology
Topic: Arlo's power stage Leaf controller runs and drives page 103
Replies: 2595
Views: 245902

Re: Arlo's power stage.... New pics on page 78

You're measuring Vds at the FET's legs or drain to GND somewhere in the board?
by Njay
Mar 31 2015 6:21pm
Forum: Motor Technology
Topic: Arlo's power stage Leaf controller runs and drives page 103
Replies: 2595
Views: 245902

Re: Arlo's power stage.... New pics on page 78

How much current is going through the FET's drain, Arlo?
by Njay
Mar 30 2015 5:53pm
Forum: Motor Technology
Topic: Exploding FETs
Replies: 26
Views: 3524

Re: Exploding FETs

Do you have apropriate caps at the DC rails very near the FETs?
by Njay
Mar 24 2015 10:31pm
Forum: Motor Technology
Topic: Arlo's power stage Leaf controller runs and drives page 103
Replies: 2595
Views: 245902

Re: Arlo's power stage.... New pics on page 34

I brought up the reverse recovery during commutation to the conducting IGBT because I believe that is what causes the big spike. To be the Irr, wouldn't it have to be at FET turn-on? How much current are you switching in that test, Arlo? Can you get a big horizontal zoom of the spike like in the ar...
by Njay
Mar 24 2015 4:08am
Forum: Motor Technology
Topic: Arlo's power stage Leaf controller runs and drives page 103
Replies: 2595
Views: 245902

Re: Arlo's power stage.... New pics on page 34

Why don't you try as you said, switching slower, with the ge cap or increasing the gate resistor. One thing at a time.
by Njay
Mar 16 2015 7:21pm
Forum: Motor Technology
Topic: Post double-pulse test scope shots of your diy controllers
Replies: 22
Views: 2417

Re: Post double-pulse test scope shots of your diy controlle

Ok. This is a old shot of the current commutation, around 15A at the end of the cycle (yellow trace). Also lots of interference at the comutation points. ab20_____.png As for the ringing, ok, it's your coil. I never saw anything similar; my shunt is between DC Link caps and FETs so I can't watch bat...
by Njay
Mar 16 2015 3:40pm
Forum: Motor Technology
Topic: Post double-pulse test scope shots of your diy controllers
Replies: 22
Views: 2417

Re: Post double-pulse test scope shots of your diy controlle

Hey, nice, thanks :) . I was referring 2nd pulse current coming down in an slight arc and not straight, but now you already said you topped your current sensor, explained. I don't know exactly what to think about the shots, they are at way higher current I've ever tried. The crazy current ringing at...
by Njay
Mar 13 2015 8:39am
Forum: Motor Technology
Topic: Arlo's power stage Leaf controller runs and drives page 103
Replies: 2595
Views: 245902

Re: Arlo's power stage.... New pics on page 34

Thanks. I found blink without delay is what I need anyways. When using Delay the whole Arduino is froze during the delay and I need it to keep watching things and hold the reset pin low. So I need to use miLLis which I'm learning now... :) Thanks for pointing that out. http://embeddeddreams.com/sit...
by Njay
Mar 11 2015 7:11pm
Forum: Motor Technology
Topic: Post double-pulse test scope shots of your diy controllers
Replies: 22
Views: 2417

Re: Post double-pulse test scope shots of your diy controlle

Do you have any with both Vgs and Vds? Interesting how your current on the 2nd pulse is comming down in "arc". Hit your sensor's current limit? One thing I noticed once, is that I have to connect the GND lead of *unused* scope channels to the GND of probes on channels I was using, in order to comple...
by Njay
Mar 08 2015 3:34pm
Forum: Motor Technology
Topic: Post double-pulse test scope shots of your diy controllers
Replies: 22
Views: 2417

Re: Post double-pulse test scope shots of your diy controlle

My measurements are all made at the MOSFET legs. Including a really short GND path from FET source to probe, right? Interesting that you get a bump vs a dip. I too get a bump, but only when using a differential probe. Using a normal probe I get a dip which is what I would expect given my current un...
by Njay
Mar 08 2015 8:19am
Forum: Motor Technology
Topic: Post double-pulse test scope shots of your diy controllers
Replies: 22
Views: 2417

Re: Post double-pulse test scope shots of your diy controlle

I'm pretty sure it's not dissipating more, at least based on the papers I've read an my understanding of what causes this resonant peak. I guess you don't have a way of measuring the drain current during the switch. That overshoot is energy from the turn on of the freewheeling diode + the stray L i...
by Njay
Mar 07 2015 11:24pm
Forum: Motor Technology
Topic: Post double-pulse test scope shots of your diy controllers
Replies: 22
Views: 2417

Re: Post double-pulse test scope shots of your diy controlle

See 16 0nf_vs_68nf_ds_200ns_off.png . The time the current takes to turn off is the width of the top of the big lump (from when Vd starts to slow down, can't be seen exactly in your shot) on the green wave (the 1st lump) - the period marked red in the pic below. What if the red time is being replace...
by Njay
Mar 07 2015 7:54pm
Forum: Motor Technology
Topic: Post double-pulse test scope shots of your diy controllers
Replies: 22
Views: 2417

Re: Post double-pulse test scope shots of your diy controlle

The ringing Vgs switching on reminds me of this. The green graph is "Vgs" measured but before the gate resistor (the yellow is the real Vgs). Measuring with probe ground lead or far from the FET also gives waves with deep ringing.
by Njay
Mar 07 2015 2:34pm
Forum: Motor Technology
Topic: Post double-pulse test scope shots of your diy controllers
Replies: 22
Views: 2417

Re: Post double-pulse test scope shots of your diy controlle

From what I've seen another person post, the coil is only ~$150 USD, the bulk of the price is in the integrator just as you suspect :) When you realize that the integrator has to deal with small diferential integration, you realize it's going to be costly :). I actually suspect it needs to have som...
by Njay
Mar 07 2015 8:28am
Forum: Motor Technology
Topic: Post double-pulse test scope shots of your diy controllers
Replies: 22
Views: 2417

Re: Post double-pulse test scope shots of your diy controlle

It's in between, I just wanted to show the relevant data, behaviour of switching ON/OFF. No I don't have any Rogowski coils, but that would be really, really interesting to have. There are ones you can (barely) put around a big FET's leg but I don't even want to look at the price (it's a "system as ...
by Njay
Jan 20 2015 1:56pm
Forum: Motor Technology
Topic: Futterama's power stage for Lebowski's controller IC
Replies: 188
Views: 22699

Re: Futterama's power stage for Lebowski's controller IC

Futterama wrote:Now, they still disagree on the snubber capacitor value for critical damping. The NXP appnote above uses a calculation, the TI paper uses a thumb rule. The results are nowhere near each other :?
Cool, space to innovate :)
by Njay
Jan 15 2015 3:42pm
Forum: Motor Technology
Topic: MOSFETS
Replies: 13
Views: 1603

Re: MOSFETS

Hey Luke, what's the improvement of this 7718 over the 4368? Seems very very marginally better at RDSON (by 10 - 50 uOhm...) and has a much higher gate charge, same max ID, same power dissipation, ...
by Njay
Jan 05 2015 8:11pm
Forum: Motor Technology
Topic: Futterama's power stage for Lebowski's controller IC
Replies: 188
Views: 22699

Re: Futterama's power stage for Lebowski's controller IC

Good, you're doing great :) DC-DC converters is also a fascinating subject. You should build yourself a basic dummy load (constant current sink), it's very simple and yet extremelly useful for several things. I've built something like this exactly for some DC-DC converters tests, with components I h...
by Njay
Dec 23 2014 9:16pm
Forum: Motor Technology
Topic: My new 18 FET TO-247 layout riding video page 10
Replies: 308
Views: 43312

Re: My new 18 FET TO-247 layout for Lebowski Controller

For ground leads I've tried both on the passive probes. Tough to get those tiny spring clips to stay put or even the leads aligator with it's long loop which loves to pick up noise. I sometimes just solder the GND spring tip to the PCB, helps alot :) . I also solder small pieces of wire (<1/2inch) ...
by Njay
Dec 23 2014 2:54pm
Forum: Motor Technology
Topic: My new 18 FET TO-247 layout riding video page 10
Replies: 308
Views: 43312

Re: My new 18 FET TO-247 layout for Lebowski Controller

I have a few comments, but you must keep in mind that my experience is at a much lower current and lower voltage, and that therefore I'm going to avoid to make "value" statements, so I'm just comparing to what I've seen on my experiences. "passive probe showing 600a passing through it" [ A is the co...
by Njay
Dec 23 2014 2:25pm
Forum: Motor Technology
Topic: My new 18 FET TO-247 layout riding video page 10
Replies: 308
Views: 43312

Re: My new 18 FET TO-247 layout for Lebowski Controller

I usually use a motor in my tests, around 1m away from the working area. I think you're absolutely right in that the test conditions must be exactly the same so that you can do comparisons. You're measuring with the GND spring (if using a non-diff probe) and probing directly at the FET's pins, right...
by Njay
Dec 22 2014 3:51pm
Forum: Motor Technology
Topic: My new 18 FET TO-247 layout riding video page 10
Replies: 308
Views: 43312

Re: My new 18 FET TO-247 layout for Lebowski Controller

I've never striped a probe, but I have soldered the GND springs to PCB on a few occasions, more because of the mechanical stability. Still haven't found probe to PCB adapters.
by Njay
Dec 22 2014 2:39pm
Forum: Motor Technology
Topic: DIY 6FET Controller help
Replies: 299
Views: 35282

Re: DIY 6FET Controller help

SjwNz wrote:After looking at the gates of one of the HiSide fets which I was not to happy with as there was some weird stuff going on around the miller plateau area during turn on, (...)
Did you take the measurement with the ground clip and the probe directly on "top" of the FET?
by Njay
Dec 15 2014 8:56pm
Forum: Motor Technology
Topic: My new 18 FET TO-247 layout riding video page 10
Replies: 308
Views: 43312

Re: My new 18 FET TO-247 layout for Lebowski Controller

When I was testing the other day I was thinking of monitoring the RDSon value to estimate Tj so that I could set a safety margin of say 10-25% under the 175c die temp max, then let the controller run the silicon to that limit. There's another method, I've been wanting to do this for some time on a ...