Author Topic: Peak And Hold Low Z Injector drivers  (Read 34753 times)

Offline jbelanger

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Re: Transient Supression Diode with Peak And Hold Low Z Injectors
« Reply #15 on: October 31, 2007, 10:16:19 pm »
Colin,

Actually, the FET driver is the IXDN404SI if I can rely on the schematic. This driver is non-inverting and is a bit more robust that the MC34151.

You can't use the FETs on the VEMS board because the current needs to go through the sense resistor on the p&h board. If you wanted to do that anyways, you'd have to disconnect the FET's pin that goes to ground, connect it to the corresponding pad for the Darlington transistor on the p&h board, and then connect the injector ground on the p&h board to the VEMS ground pad. That could probably be done but that would make for a pretty screwy installation. Another point is that I'm not sure if the VEMS FET would behave correctly when being driven by the LM1949 on the p&h board. FETs like to be either on or off but they'd have to be partially on during the hold phase and they'd probably heat up quite a bit. That may not be a problem but I'd have to check the specs and/or do tests to have an idea.

As for using higher values for R18,..., in itself, that wouldn't be a good solution. What's needed is a voltage divider which can be done by 2 resistors. Fortunately, the p&h board has a pull down resistor (R10-13) which could be used for the voltage divider together with R18,... If you were to use 1K Ohm for R18... and 430Ohm for R10-13 you'd have a signal that would be within the spec of the LM1949 with a battery voltage from less than 8V to more than 16.5V which should cover pretty much all cases from cold start with weak battery to a poorly functioning voltage regulator.

So the ideal setup would be to connect the p&h board in place of the FETs while replacing R18,R21,..., with 1kOhm resistors and replacing R10-13 on the p&h board with 430Ohm resistors (Digikey part# 430EBK-ND) and using the VEMS flyback with the p&h board Darlington transistors. With that, you'd need to find a way to heatsink the Darlingtons. If you don't mind drilling holes in your case, using the case as heatsink is a good solution if the case is thick aluminium. You'll need to use mica insulators to keep the transistors from grounding to the case.

Jean

Offline Sprocket

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Re: Transient Supression Diode with Peak And Hold Low Z Injectors
« Reply #16 on: October 31, 2007, 11:05:56 pm »
Jean thanks for that, i see a solution aproaching ;D.

I had intended to mount the P&H board inside the Alubos case above the Genboard and sinking the Darlington transistors ( I had always considered using these for the reason you lay out) in a similar manner to how the Genboard FETs are sinked, I have plenty of insulator sheet, this would not have been left out.

Ok then, this sounds like a plan.

I will try this with the altered onboard resistors, fairly easy to do, hard wire from the FET pads to the P&H, swap the resistors on the P&H board and give it a go. That way i still have my expensive fuse ;D protecting the processor some what.

Need to see if I can get these parts from Maplins or RS components before I go away next week, i want to do this mod, when im in the hotel, it'll give me something to do :D

This the pinacle of the R&D :D

Boom and bust, maybe with a bit of smoke :D ;)

I will physicaly check the FET driver chip thats onboard. http://dkc3.digikey.com/Media/PDF/Data%20Sheets/IXYS%20PDFs/IXDF404,IXDI404,IXDN404.pdf
« Last Edit: October 31, 2007, 11:40:14 pm by Sprocket »

Offline Sprocket

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Re: Transient Supression Diode with Peak And Hold Low Z Injectors
« Reply #17 on: October 31, 2007, 11:58:08 pm »
Looks like its the MC33151 chips to me. This is a blown up pic of the top of the board I took about two weeks ago


Offline jbelanger

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Re: Transient Supression Diode with Peak And Hold Low Z Injectors
« Reply #18 on: November 01, 2007, 12:11:50 am »
You're right, it definitely looks like the MC33151. That means the signal is inverted so if you were to remove them, you'd need to change the software somehow to change the signal polarity. It wouldn't be a big change but it might be a challenge to find where and how to do it.

Jean

Offline Sprocket

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Re: Transient Supression Diode with Peak And Hold Low Z Injectors
« Reply #19 on: November 01, 2007, 12:25:34 am »
Could always use the non inverted ones on just outputs for one P&H board, but are we removing these?

Offline jbelanger

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Re: Transient Supression Diode with Peak And Hold Low Z Injectors
« Reply #20 on: November 01, 2007, 12:41:56 am »
If you had you board with these FET drivers and you had your injectors connected to the FETs then you don't need to change anything (FET driver or software) to use the solution proposed above (change resistors and remove FETs).

All I was saying is that if you were to go to the solution of connecting the p&h board directly to the CPU then you would have had to change the software because it must be inverting the signal for it to be of the correct polarity after being inverted again by the FET driver. You would have needed the software to not invert the signal for it to go directly to the p&h board.

So you can just ignore my last post (and the text above) and go with the changed resistors and FET removal solution. You now only need to choose the location of the p&h board and how you're going to wire it. About wiring, the signal from the FET driver INJG0x requires only small wires because there's very little current going through. The injector current is obviously quite large so will require bigger wires (same as what you have going to your injectors in the wiring loom). The routing of those 8 wires is likely going to be a major factor in where you position the board.

Jean

Offline jbelanger

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Re: Transient Supression Diode with Peak And Hold Low Z Injectors
« Reply #21 on: November 01, 2007, 12:44:28 am »
By the way, if this is deemed OT for this forum by the admin, let me know and I'll discuss this privately with Colin.

Jean

Offline rob@vems.co.uk

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Re: Transient Supression Diode with Peak And Hold Low Z Injectors
« Reply #22 on: November 01, 2007, 09:01:56 am »
Nope, its fine, carry on with the discussion.

I'm happier with the P&H board being connected after the drivers as its one more level of isolation and therefore protection for the AVR.

Rob

Offline Sprocket

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Re: Transient Supression Diode with Peak And Hold Low Z Injectors
« Reply #23 on: November 01, 2007, 08:22:44 pm »
replacing R10-13 on the p&h board with 430Ohm resistors (Digikey part# 430EBK-ND)

Jean, are these resisters originaly required? I see the positions on the board, but the BOM and the schematic do not show these.

Also, Digikey did not have any of these resistors in stock 39KEBK-ND, are these plain ordinary carbon film resistors i can source from Maplins or RS Components in the UK? I will have to source the 430EBK-ND resistors anyway

Also need to source 1k surface mount resistors as well, not looked in the rescue kit yet

I now have my digikey parts except those above ;D, let the build commence, Just waiting on my new ECU case ::)

Offline Sprocket

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Re: Transient Supression Diode with Peak And Hold Low Z Injectors
« Reply #24 on: November 01, 2007, 09:17:13 pm »
Unfortunately i cannot find anywhere that stocks 1k surface mount resistors, Maplins are useless, more of a toy shop, and RS no longer stock these
http://rswww.com/cgi-bin/bv/rswww/searchBrowseAction.do?Nr=avl%3auk&N=4294962297%204294890512&forwardingPage=search&name=SiteStandard&obs=fObs&callingPage=/jsp/browse/browse.jsp&BV_SessionID=@@@@0166120325.1193945880@@@@&BV_EngineID=cccladdmghkemkecefeceeldgondhgj.0&cacheID=uknetscape

Next best thing is this, Will these do?
http://rswww.com/cgi-bin/bv/rswww/searchBrowseAction.do?Nr=avl%3auk&N=4294962297%204294810314&forwardingPage=search&name=SiteStandard&obs=fObs&callingPage=/jsp/browse/browse.jsp&BV_SessionID=@@@@0166120325.1193945880@@@@&BV_EngineID=cccladdmghkemkecefeceeldgondhgj.0&cacheID=uknetscape


Lowest watt carbon film 39k is 0.33
http://rswww.com/cgi-bin/bv/rswww/searchBrowseAction.do?Nr=avl%3auk&N=4294962302%204294898017&forwardingPage=search&name=SiteStandard&obs=fObs&callingPage=/jsp/browse/browse.jsp&BV_SessionID=@@@@0166120325.1193945880@@@@&BV_EngineID=cccladdmghkemkecefeceeldgondhgj.0&cacheID=uknetscape

but can find metal film at 0.125 watt, will these metal film be suitable? A resistor is a resistor, right? :-\
http://rswww.com/cgi-bin/bv/rswww/searchBrowseAction.do?Nr=avl%3auk&N=4294962300%204294951423%204294913927%204294867130&forwardingPage=search&name=SiteStandard&obs=fObs&callingPage=/jsp/search/search.jsp&BV_SessionID=@@@@0166120325.1193945880@@@@&BV_EngineID=cccladdmghkemkecefeceeldgondhgj.0&cacheID=uknetscape


Again the 430 ohm only available in a 0.66 watt carbon film
http://rswww.com/cgi-bin/bv/rswww/searchBrowseAction.do?Nr=avl%3auk&N=4294962302%204294867102&forwardingPage=search&name=SiteStandard&obs=fObs&callingPage=/jsp/browse/browse.jsp&BV_SessionID=@@@@0166120325.1193945880@@@@&BV_EngineID=cccladdmghkemkecefeceeldgondhgj.0&cacheID=uknetscape

But available in 0.25 watt Metal film
http://rswww.com/cgi-bin/bv/rswww/searchBrowseAction.do?Nr=avl%3auk&N=4294962300%204294951423%204294867102&name=SiteStandard&forwardingPage=line&R=0164233&callingPage=/jsp/search/search.jsp&BV_SessionID=@@@@0166120325.1193945880@@@@&BV_EngineID=cccladdmghkemkecefeceeldgondhgj.0&cacheID=uknetscape


Offline Sprocket

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Re: Transient Supression Diode with Peak And Hold Low Z Injectors
« Reply #25 on: November 01, 2007, 10:15:30 pm »
6 off 1K surface mount resistors are in the rescue kit and are the '102' resistors. I understand the numbers on these things now. 10 to the power of 2 ::)

Offline jbelanger

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Re: Transient Supression Diode with Peak And Hold Low Z Injectors
« Reply #26 on: November 01, 2007, 11:01:00 pm »
replacing R10-13 on the p&h board with 430Ohm resistors (Digikey part# 430EBK-ND)

Jean, are these resisters originaly required? I see the positions on the board, but the BOM and the schematic do not show these.

Also, Digikey did not have any of these resistors in stock 39KEBK-ND, are these plain ordinary carbon film resistors i can source from Maplins or RS Components in the UK? I will have to source the 430EBK-ND resistors anyway

Also need to source 1k surface mount resistors as well, not looked in the rescue kit yet

I now have my digikey parts except those above ;D, let the build commence, Just waiting on my new ECU case ::)

Colin,

The BOM for the v1.1 board has R10-13 specified in it but they're not required in the usual installation. They're for an upcoming feature but will be very useful now. If you look at my web page you'll have some information about those and the v1.1 BOM. You probably have the v1.0 BOM.

R10-13 as well as the 39K resistors are all 1/6 W resistors which are 3.4mm long. That's the main issue if you're looking for a replacement otherwise you'll have a hard time fitting them to the board. The board has the resistor pads 0.3" (7.5mm) apart so you have to account for the resistor body length and the lead radius. Also, anything with at least 1/8W will be fine for both values.

If you have trouble finding 39K resistors, you could go with a slightly lower or higher value because it's not a critical value. The resistors are there to limit the peak phase time in case the peak current can't be reached (likely due to low battery voltage). With 39K, the time is limited to 3.9ms so if you go to a 36K resistor the time limit will be 3.6ms or if you with 43K the time limit will be 4.3ms.

Jean

Offline Sprocket

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Re: Transient Supression Diode with Peak And Hold Low Z Injectors
« Reply #27 on: November 10, 2007, 06:52:09 pm »
We have progress ;D

I have been busy swapping the Genboard into the intended Alubus 'Vems' case. While at it I soldered new EGT2, VR2 and P259 chip on board, so far everything checks out :D, although i have no way of checking the VR chip :-\

Anyway. I source some 0.6w Metal film resistors and soldered everything onto the P&H board excluding the flyback diodes and transister as discussed with Jean. One thing i did do was solder on the resistor and zener diode which is also part of this circuit, This wont be a problem will it Jean?

I also changed the resistors on the Genboard which is after the FET driver chip and before the FETs, changed them to 102s (1000 ohm). see picture, resistors circled in yellow

I removed the four FETs from the middle row and moved them to the ignition chanels to keep the output capebility. At the same time I installed two new IGTBs for possible future COP/ sequential ignition.

After moving the above FETs, i soldered on wires from the P&H board to the FET pads, checked everything was good with no shorts. The P&H board is mounted, inverted, on the top part of the Alubos case, with one end of the board in the second pcb chanel, with the other end fitted with two stand offs. The FETs are clamped in a similar fashion to the Genboard with insulator sheet between the case and the FETs, FETs checked for any shorts to the case or each other. All good. I think its quite neatly packaged to be honest. Maybe worth considering a longer board to use the pcb slots and just clamp the FETs, obviously VEMS specific then, but how many people would use these to justify the need :-\

It may be possible to get two of these boards in the case back to back, as Jead had designed for Megasquirt, but it will be damd tight with the wiring, but not impossible ;)

I now need to rewire the Econoseal connectors and reconfigure the P259 outputs back to my original configuration, rewire the injector to the correct chanel, remove the resistor, and start again with the calibration :D :D :D.

Oh one other thing, I remover the Transient surpression diode from the flyback wire inside the case so I can install it in the loom instead, that way I can keep an eye on its temperature and remove it if required. I know you stated to remove it Rob, but Jean said to keep it, so im going to do the research on it to find out one way or the other. Still not really sure on whether its required or not.

Just a note on the config of the injector, currently the single injector is configured in the H[0] tabele as 0-1 with the divider as 1. The question i am asking, is if I set the divider to two, will this reduce the injector firing by half? IE instead of firing every 360 degrees per cycle, it fires once every 720 degrees per cycle??

Reason I ask this is, as i have mentioned previously, the injector Im using is providing far more fuel that it did on the OEM system and wodering if the divider is a factor in this, not knowing how many times the OEM system fired the injector per cycle.

Onwards and upwards, I aint smoked it yet :D












Offline jbelanger

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Re: Transient Supression Diode with Peak And Hold Low Z Injectors
« Reply #28 on: November 10, 2007, 08:17:24 pm »
...

Anyway. I source some 0.6w Metal film resistors and soldered everything onto the P&H board excluding the flyback diodes and transister as discussed with Jean. One thing i did do was solder on the resistor and zener diode which is also part of this circuit, This wont be a problem will it Jean?

...

Oh one other thing, I remover the Transient surpression diode from the flyback wire inside the case so I can install it in the loom instead, that way I can keep an eye on its temperature and remove it if required. I know you stated to remove it Rob, but Jean said to keep it, so im going to do the research on it to find out one way or the other. Still not really sure on whether its required or not.

...

The resistor and zener diode won't be a problem because without the flyback diodes and TIP42, they're not connected to anything but ground. As for the transient suppression diode, you need it if you're not using the p&h board's flyback. I think that Rob was saying to remove it and use the p&h board's flyback components which is another way to do it.

As for board size, if I get enough demand for it I could do it. Do you have exact dimensions for it or a link to the case dimensions? I could also adapt the board for a similar installation by removing the flyback components and adding the resistor for the voltage divider.

I look forward to hear how things go from here.

Jean

Offline Sprocket

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Re: Transient Supression Diode with Peak And Hold Low Z Injectors
« Reply #29 on: November 10, 2007, 09:36:25 pm »
Jean The transient surpession diode is an extra, the flyback circuit is onboard. Normaly when running PWM the diode is left out as it can fry the flyfack circuit, when running saturated, the diode reduceds the injector closing time resulting in better response. I am in other peoples hands with this as i havent a clue, lol.

If the Peak and Hold mode operates like a saturated injector, then i would suggest it is fine left in circuit. If however it acts more like PWM it may be a bad idea??? With or with out the diode, there is still a flyback circuit on board. I believe this to be a low voltage flyback, there is a high voltage 'power' flyback add on circuit for use with High Z injectors( substituteed with the transient surpression diode), where the low voltage is used on low Z injectors.

Fly back circuitry is somewhat of a mystery to me, other than the basic theory of why its required. :D

One other thing. I managed to find out how and where to change the invertion of the injector drive signals of the processor, its within the 'my_make.ini' file, part of the firmware configuration :) Not that it matters now :D

Just need to test it now, dont know when as im going to be mad busy the next couple of weeks with work and family stuff.