Paul & Sabrina's cheap DIY 144v motor controller - Page 334 - Fuel Economy, Hypermiling, EcoModding News and Forum

MPaulHolmes · 04-18-2010, 03:41 PM

Quote:

Originally Posted by jackbauer

ok did a few more tests on the "emergency shutdown" code I received from Paul. If the throttle is at zero and the lem sees 7 amps or over it shuts down and kills the contactor which is great. BUT. If the throttle is even slightly applied , the igbt fails short circuit and the throttle is brought back to zero , the controller continues to operate and the contactor stays closed.

Oh dear... Once the contactor opens, applying throttle should do nothing. No more driving allowed until the next time the power has been cycled. Let me fix that. Do you mean your igbt actually FAILS permanently?! That's horrible!

jackbauer · 04-18-2010, 05:28 PM

hey Paul. sorry for my bad grammer what i meant was that i simulate the igbt failure by shorting b- and m-. if i apply the short at zero throttle the controller shuts down as planned. if on the other had i apply the short when some throttle is applied , then bring the throttle to zero with the short still applied , the contactor stays closed and the software continues to execute. i was trying to simulate a power stage failure during driving.

MPaulHolmes · 04-18-2010, 05:31 PM

I sent you the fix. I forgot to disable interrupts on the failure infinite loop. oops!

jackbauer · 04-18-2010, 05:32 PM

many thanks paul i'll check it out and report.

Weisheimer · 04-18-2010, 08:26 PM

Quote:

Originally Posted by jackbauer

Did a few quick mods to the "bauer-con" this morning. Changed C20 and C21 to 16uf 35v tantalum and added a 1uf 1000v mkp snubber across M- and B-. No more ripple on the gate drive.

It looks better! I just can't help but wonder if it is the tantalums on the power circuit, or if it is the snubber, that made the big difference. Have you tried taking the snubber off to see the difference?

I wouldn't do anything further on the DC/DC, no sense losing what you've already paid for and it probably wouldn't make that much of a difference anyway.

I'm finally home now, and need to get a small parts order made, so I can work on a very similar project. I have some of the modules from Adam too. I've got the heatsink drilled and tapped, and need to have it cut down a bit
to fit the space that is available.
Next up, take the 1"x.25" bus bar that I scavenged and have it cut down to .75"x.25" to fit the current sensor.
I'll use a control board from Paul and will likely add a second gate driver to the mix and drive 2 modules per gate driver.

Have you tested this in the car yet?
You've made great progress.

Mark

Flatmann100 · 04-18-2010, 09:15 PM

Jack, here where I work we have a lot of compound shunt DC motors. We utilize field weakening to achieve higher RPMs by varying the current to the fields. You can only weaken the fields so much and the machine will become unstable. We know where full fields should be set and we also know where things will become unstable if they lower the current too much. One of the safe guards for monitoring the field strength is the "field loss" circuit. It watches to see that fields do not go lower than a pre-set level. If the fields drops below a certain level the "FL" relay drops out and opens the main contractor. Of course all hell breaks loose when this happens because all that energy has to go somewhere. There is comparing logic in the program which monitors Current Feed back, Speed reference, Ramp tracking, Linear time for both acceleration and deceleration. Everything begins with current feed back. We check this before we attempt and drive adjustments. Since you have the LEM maybe you can add logic.

What we have is quite complicated for several reasons but if your looking to play around with field weakening adding some pre-sets and comparing inputs might give you the control your looking for. I will look around for some of our old tech manuals they gave us for training which might be helpful to you and Paul.

I’ll see what else I can dig up
.
Mike

steiner · 04-18-2010, 10:46 PM

Paul,

How is the SR controller coming?

You had previously mentioned you were going to use 1000 uF capacitors. Do you happen to have a part number? I'm trying to collect pieces as I go.

Thanks....

MPaulHolmes · 04-18-2010, 11:41 PM

Hi Steiner. Yes, they are of the same family as the 820uF ones, but just slightly taller. Let me find it...
Digi-Key - P11600-ND (Manufacturer - EET-ED2D102CA)

dang, 0 available.

The SR controller control board is finished. I just need to order it, but have had a temporary financial setback. hahaha. (The stupid wrong 25 current sensors that Digikey sent me) Once they reimburse me, I should have the money to order the board. The first board was a big fat failure. I used the wrong DC-DC for powering the high side driver. The next one will work. I'm using a DC-DC that's actually designed for it. Here's what I have been doing though:
First of 6 BMS boards are done (surface mount soldering by hand! My first ever!):

And here's the control board for the charger:

The power section for the charger is almost done.