DIYEFI.org Forum

I agree PWM P&H can be done and therefore doesn't worry me, that CNG from Marco will likely be used in the next spin. I can see how it can stay here, but I would tend to agree, that blah blah blah about PWM P&H really should be in the injector thread.

Also note the CNG in Marco's video has a higher than average inductance, so that video isn't exactly the same as we would expect to see in a petrol LowZ.

jharvey wrote:Also note the CNG in Marco's video has a higher than average inductance, so that video isn't exactly the same as we would expect to see in a petrol LowZ.

Do you mean impedance/resistance at DC?

- Jim

MotoFab wrote:If code isn't written to deal with a bad signal, then it really can't be called the best code can it?

Deal with appropriately, sure, produce an acceptable output from, no, you can't expect ANY code to do that. if you feed a solid 5v into an ADC when the truth is a solid 3v, the code can do precisely nothing. The other extreme is 5 vs 5, and there is a large spectrum in the middle. At some point, you can't do anything more without fixing the input. Period.

This whole PWM thing and its results deserves his own thread. Briefly, its an mbed running an rtos, powered by the SMPS that has been under testing. the pcb is just crap, but enough for making a point wether it is a good or an awful setup.

Pics of how it was last week at the bottom of this
https://picasaweb.google.com/106594625630518577845/Puma

I didn't bother on posting this until I have something consistent. If I post what I know right now it will only introduce noise to the forum :-)

PWMing an inductive load is complicated, I need to *see* howeverything behaves before I make any move.

jharvey wrote:Also note the CNG in Marco's video has a higher than average inductance, so that video isn't exactly the same as we would expect to see in a petrol LowZ.

Do you mean impedance/resistance at DC?

The impedance (which at DC is simply the resistance) is relevant to peak and hold current, and that's what I thought you might have meant.

I was asking what you meant because the amount of inductance isn't really an issue. As inductance changes, so does the charging current slope. How current slope relates to peak current isn't really going to matter. I mean, if the charging slope is shallower, and a higher peak current is needed, then the driver can be held in saturation longer before beginning PWM.

Jim