Arlo's power stage Leaf controller runs and drives page 103

HighHopes · Oct 8, 2014

The via u put for desat, are you maintaining creepage? I can move the ground plane back I was relying on the clearance settings to keep it safe but Its better to change that.

i already helped you on what creepage is, how to know what you need, what reference to use, how to identify any problems in your design and how to solve. you have already all the tools you need to figure it out. i only raised the question cause it looked odd, i did not measure or look in detail.

actually, that's how reviews are normally done.. the reviewers rarely look in detail, they just are given one day to review and of that day only have time about 1 hour.. so they just use their experience to look for things that are "odd" or "not normal" etc. and raise question "did you look into that" or "do you have this problem?" or "why did you chose this cause i never seen that before?".

Arlo1 · Oct 9, 2014

HighHopes said:
The via u put for desat, are you maintaining creepage? I can move the ground plane back I was relying on the clearance settings to keep it safe but Its better to change that.

Click to expand...

i already helped you on what creepage is, how to know what you need, what reference to use, how to identify any problems in your design and how to solve. you have already all the tools you need to figure it out. i only raised the question cause it looked odd, i did not measure or look in detail.

actually, that's how reviews are normally done.. the reviewers rarely look in detail, they just are given one day to review and of that day only have time about 1 hour.. so they just use their experience to look for things that are "odd" or "not normal" etc. and raise question "did you look into that" or "do you have this problem?" or "why did you chose this cause i never seen that before?".

I was asking if I needed to change my clamp transistors...

Arlo1 · Oct 9, 2014

Here is the last revision.

HighHopes · Oct 9, 2014

oh, my misunderstanding. if it were my design i would not have a clamp transistor at all.

there is one thing that is very important though.. the clamp function, how it works. when gate driver IC try to turn OFF it will power off with full strength until voltage reaches some value, like 2V, and then engage teh clamp. but your gate driver IC in the leaf inverter design is referenced to -8V i think, so clamp will not be asked to turn ON until gate is at -6V. this is fine, no need to change things. now, if clamp turns ON, what is clamp referenced to? i didn't check your schematic recently so i do not remember, but if it is referenced to -8V then its fine (but useless) and if it is referenced to IGBT emitter then it will actually hurt your design cause it will pull the gate to 0V rather than -8V.
so put that scenario in your mind and then go read the gate drive IC dataasheet to see if what i'm saying will happen or not and then look at your design to see if you are OK or not. hope that makes sense.

HighHopes · Oct 9, 2014

for creepage comment, this is what i was talking about:

SjwNz · Oct 9, 2014

Would the diode below stop HV from been applied to this track so there would not be a creepage issue?

Arlo1 · Oct 9, 2014

Electrical spacing. HH the link you give me says very much the same numbers as this chart.
Before you guys asked I had all the spacing at .05" or more anywhere I think there is potential for the 470v. The goal was .95" but that's really big. Spec says .9 with uncoated at sea level and .03xx" at sea level with conformal coating. I will have coating on the board and once its assembled I will spray it with silicone conformal coating. So the .05 should be ok but I adjusted things to get .06 in the tight spots to make it a little safer!

7C asked about the transistors. The part number I am planning to use is D44VH10/D45VH10‏ which is what Zombies used. I need to go double check this and I will put a whole build list together before ordering the boards.

Njay · Oct 10, 2014

HighHopes said:
for creepage comment, this is what i was talking about:

Any reason not to route that trace mainly on the component layer, then via to copper layer near the component at the left?

HighHopes · Oct 10, 2014

SjwNz said:
Would the diode below stop HV from been applied to this track so there would not be a creepage issue?

good point! yes creepage here is required as well, but for a different reason. the diode does block the high voltage such that on the anode and trace is low voltage ... but .. voltage is always "with respect to". that is low voltage with respect to the gate driver, so from gate driver's point of view, that trace is low voltage. but from the near by center ground plane (input power, current sensor area), it is high voltage!

and for the record, here is a "fun fact". voltage is always "with respect to" some reference (usually also sometimes mistakenly called ground). potential, that is "voltage" not with respect to anything .. just a collection of electrons. if you build your circuits to operate on potential rather than voltage, you'd be in for a curious ride. :idea:

HighHopes · Oct 10, 2014

Any reason not to route that trace mainly on the component layer, then via to copper layer near the component at the left?

what i was trying to avoid was placing the via on the cathod side of the desat diode and (to a lesser degree) between the RC desat filter and gate driver IC. putting high voltage on a via is tough thing to manage, so i want to avoid that. vias tend to collect noise so i did not want it between RC filter and gate driver IC. that was my thinking. so long as those things are satisfied, i'm pretty flexible. for the record, i would have put the via in the ground plane area, not in the isolation area.

Arlo1 · Oct 10, 2014

Ok So I'm reading up on the ACPL-333J vs the ACPL-339J and so far I don't see much advantage to the 339J other then it will pull power switch gate with a separate pin then it used to turn it on with.

OH and the 333J is 250 ns propagation and the 339J is 300ns propagation.

Arlo1 · Oct 11, 2014

HighHopes said:
What type of diode will you use. What reverse rating voltage can it cope with?

Click to expand...

two things to look for in a good desat diode. fast recovery and <10pf junciton capacitance. you will need at least 900V rated.

when arlo did the math he came up with a needed "zener" voltage of 2.5V or something like that. this value is pretty low, he has his choice of using two additional diodes, or one 2.5V zener. personally i like the zener method even though it adds a lot of varation.

Is this ok ? http://www.digikey.ca/product-detail/en/CMR1-10M%20TR13/CMR1-10M%20DKR-ND/4807306
Digikey # CMR1-10M DKR-ND 8pf 1kv and fast recovery.

HighHopes · Oct 11, 2014

Digikey # CMR1-10M DKR-ND 8pf 1kv and fast recovery.

well, the datasheet doesn't actually state what the reverse recovery time is.. but otherwise it looks good. i would try it.

Arlo1 · Oct 12, 2014

OK this seems to have slowed down. I am moving the discussion to a new thread just for the LEAF/IGBT based inverter build as I feel the boards are close. I will now work through my mosfet low voltage controller on this thread until I feel its close to testing. Then make thread for it as well to clear things up.

New igbt/leaf inverter thread.

7circle · Oct 12, 2014

The Transistors you reffered to are TO-220... .. D44VH10

Zombies boards aren't driving to 15V and low to -9V.
But he is going surface mount... perhaps he found an equivalent device.
So the Veb emitter to base voltage range will see around 24V.
Have a look at what AVAGO recommend in their app notes.

I found a reference:
The BG1A driver board described in this pdfhttp://4hv.org/e107_files/public/1352276563_2292_FT146191_igbt_gate_drive.pdf
suggests the use ...

Q1 NPN Booster transistor 15A, 80V Motorola
D44VH10
Q2 PNP Booster transistor 15A, 80V Motorola
D45VH10

I can't find there equivalent ON-Semi cousins in surface mount DPAK with such high current ...15A

D44VH10
15 A
COMPLEMENTARY SILICON
POWER TRANSISTORS
80 V, 83 W

Veb about 7.5V

Maybe the http://www.onsemi.com/pub_link/Collateral/MJB44H11-D.PDF
will do in D2PAK 3
"MJB44H11 (NPN), NJVMJB44H11 (NPN), MJB45H11 (PNP), NJVMJB45H11 (PNP)"
But only 10A
Veb is about 5V

Maybe this is why some go to mosfet booster stage.

Arlo1 · Oct 12, 2014

I got to do some digging. Maybe I looked up the wrong number.

Edit: Its been so long I can't remember or find what part number I was planning to run for the gate transistors.

The onsemi 45H11 PNP is not in stock anywhere in the 10 amp rating.

HighHopes · Oct 13, 2014

so long as you use transistors (not mosfet), have sufficient current/voltage rating and the pair are complementary type, then you're good. actual part number of other reference designs no too important, so feel free to shop around. just meet the above requirements.

Arlo1 · Oct 13, 2014

So I am not sure what I need for specs... I think a decent amount above the voltage driving the gate which is 15 and -9 which would = 24v so 60v should be lots of head room for spikes.

10amp rated? maybe these? http://www.digikey.ca/product-detail/en/MJD2955TF/MJD2955TFCT-ND/3504460 digikey number MJD2955TFCT-ND
and this for NPN http://www.digikey.ca/product-detail/en/MJD3055TF/MJD3055TFDKR-ND/1473951 digikey number MJD3055TFDKR-ND

Arlo1 · Oct 13, 2014

I'm looking at these for the 2.5v Zener http://canada.newark.com/on-semiconductor/mmsz5222bt1g/zener-diode-500mw-2-5v-sod-123/dp/26K4591

HighHopes · Oct 13, 2014

you should do the gate driver math so you know what peak current you need to supply and thus what your transistors need to be rated for. try not to guess with anything you do.. take the time.

you should study again the post i made on how the desat circuit functions. picture this, the gate driver IC produces 250uA for the desat circuit. this current flows through the zener diode and then the diode and then the IGBT and back to the gate driver IC. now let me ask you this, if there is but 250uA in your zener, do you think the device will reach the 2.5v you expect? if the answer is YES then keep that zener, otherwise select a new one (but use this new found knowledge while doing so).

^ that's me encouraging you to take the designer's role. i know you have it within you. do your homework then ask questions :wink:

Arlo1 · Oct 13, 2014

Ok so here they say take the total voltage swing and devide that by total resistance gate resistors + modual internal resistance.
and then that will be approximately 70% of what's required.

Problem I can't seem to find the modual internal gate resistance here.
http://www.bjrtd.com/pdf/1MBI800U4B-120.pdf

Other wise I have 24 / 3 ohms = 8 and 8 / .7 = 11.42 now if the modual has any sort of internal resistance .45 ohms or more the 10 amp peak will be sufficient.

Arlo1 · Oct 13, 2014

HighHopes said:
you should study again the post i made on how the desat circuit functions. picture this, the gate driver IC produces 250uA for the desat circuit. this current flows through the zener diode and then the diode and then the IGBT and back to the gate driver IC. now let me ask you this, if there is but 250uA in your zener, do you think the device will reach the 2.5v you expect? if the answer is YES then keep that zener, otherwise select a new one (but use this new found knowledge while doing so).

^ that's me encouraging you to take the designer's role. i know you have it within you. do your homework then ask questions :wink:

So if the desat threshold is 6.5v and the circuit requires a 100 ohm resistor to limit the current then the most the circuit should ever see is .065 amps is it not?

Edit: I just realized you said 250uA not 250mA sorry.

Arlo1 · Oct 13, 2014

OK so I searched all your posts. I found one on Zombies thread about the desat detection. http://endless-sphere.com/forums/viewtopic.php?f=30&t=51342&p=846765&hilit=Desat#p846765

I also could not find the mention of the Desat current for the Avego chips in the spec sheet.

You point out the 250uA the chip has for the desat pin. I looked and maybe found something. http://www.comchiptech.com/cms/UserFiles/CZRU52C2%20THRU%20CZRU52C39-RevB.pdf
I can either choose 2.4v with 100uA or 2.7 with 75uA http://www.digikey.ca/product-detail/en/CZRU52C2V4/641-1021-1-ND/1121143

HighHopes · Oct 15, 2014

you can also look at zombiess circuit to find out what desat zener he chose and pick from same family.

the 250uA is not so obvious in ACPL-333J datasheet. it is in the blanking charge, typical 0.24mA = 240uA.

7circle · Oct 15, 2014

DESAT current in 333J spec is called Ichg and Idschge.

It could be described more clearly .. the overall operation of the desat circuit using longer time frame... say to show two pulses.
The chip internals control it like an I/O pin.
The desat pin doesn't just monitor the voltage.
It resets the Cblank cap by shorting it out with discharge current up to 30mA.
Then when Vout goes high the DESAT releases the discharge short and it supplies 250 to 280uA that
will charge Cblank and also any load seen into RES/zener/diode / igbt-c less the igbt Vce... etc

...

Arlo's power stage Leaf controller runs and drives page 103

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