Paul & Sabrina's cheap DIY 144v motor controller

[adamj12b]

Originally Posted by Nevyn

Glad you're home safe and sound! I just finished re-reading this thread (yes, the WHOLE THING) and will hopefully be able to be somewhat helpful once again.

My version 1A of the 1kA IGBT board seems to be working. Other than backwards LED, that is. Man, I was soldering last night and forgot to fix that! Derp!

RTD connection works all good, except for the "restart" command - all it does is break communication! Such is life. Throttle input seems to work, current sensor seems to work (took me a while to read through the thread and find the pinouts for the 3-wire Melexis compared to the 4-pin header on my board!), so I think I'm ready to try and interface it with the old BG2A IGBT driver board!

Finally, Paul, one of your early testers is testing! I'm only what, 2 years behind Isaac_Alaska?

What software version are you using? I think Paul changed something in anything above 1.1b and that broke the restart command.

-Adam

[Nevyn]

Um...I would have to say I don't know. I think I've got branch code due to heading down the IGBT path and having a board with built in precharge circuit.

I got it from Isaac; RTD comes up and says "Cougar OS 1000amp controller firmware v0.1."

[johnsiddle]

Originally Posted by MPaulHolmes

I just got done with a 1500 mile drive with my 1 year old in the back seat from Olympia to Maricopa. Boy that wasn't fun! We even ran over the big fat middle section of a dead deer. Rain and 60 in Washington, sun and 105 down here. haha.

You can definitely get multiple gate drivers to work. Ian Hooper (who is the reason I started working on controllers for cars in the first place) has made reliable controllers using up to 6 drivers and 12 mosfets. He didn't tie the outputs (pwm) of the drivers together though. He just had 2 mosfets per driver on a separate little driver board. Maybe the blowup was caused by something else? Those drivers have like a 15nS response time. Do you know at approximately what conditions (current of motor, current from batteries, pwm duty) the controller blew up?

mora, I'll try to find the .hex file. Man, I'm awful with knowing which version is which, and not keeping old versions. I tried SVN once, and wanted to stab myself in the eyeball with a fork afterwards.

Thanks Paul.
When it blew up I was booting it from a standing start, I dont know what current was being pulled, I do know that during my short runs at quite a high accelleration in the road outside my house I was pulling 400A as indicated by the 75ma shunt/ammeter. Batteries were up at 153v and are new,

I have redesigned my power amp board with just one 4451 driver (TO220 package) and ten 10ohm resistors into ten 75A 600V IGBT's. I was using ten 6A drivers into ten 130A 200v MOSFETs, same ones that you used.

I think when this board goes live I will set up a video camera pointed at the meters so I can see what happens.

I dont know how to safely check the current limiting without booting it and seeing what happens. I have calculated the setting (500A) using the online datasheet for the Lem HTFS I am using. I will set it at 300A next time.
I could not work out from your cct diagram exactly how the current limiting was done. It seemed to me that it inhibited the PWM drive to the fet drivers and returned it as soon as the current dropped. There is a line from the sensor that goes to the processor, but I did not know if it is an input or output.
Adam said that it operates very quickly and sharply so I think I worked out correctly. I thought the juddering was the current limiting working but possibly just the FETS blowing as it was quite slow.

[MPaulHolmes]

The current sensor line to the microcontroller is an input (to the microcontroller). The output of the current sensor also goes to a comparator. As soon as the voltage output of the current sensor goes above the special trip point that corresponds to the maximum current, the output of the lm293 (or 393) changes from high to low. That causes the nands to latch into a state that gives a high output to the mosfet driver (which is OFF). The only way to clear the overcurrent fault state is to bring the "clear" pin low and then high again. As soon as the pin goes high, the nand latch is cleared and things go back to normal. The default setting in software is to clear the nand latch at about 4kHz. It's probably safer not to clear it at all, but you don't want to be driving down the freeway and all of a sudden, the car turns off for no reason other than a single spurious overcurrent event.

[johnsiddle]

Originally Posted by MPaulHolmes

The current sensor line to the microcontroller is an input (to the microcontroller). The output of the current sensor also goes to a comparator. As soon as the voltage output of the current sensor goes above the special trip point that corresponds to the maximum current, the output of the lm293 (or 393) changes from high to low. That causes the nands to latch into a state that gives a high output to the mosfet driver (which is OFF). The only way to clear the overcurrent fault state is to bring the "clear" pin low and then high again. As soon as the pin goes high, the nand latch is cleared and things go back to normal. The default setting in software is to clear the nand latch at about 4kHz. It's probably safer not to clear it at all, but you don't want to be driving down the freeway and all of a sudden, the car turns off for no reason other than a single spurious overcurrent event.

Thanks for that Paul.
I almost got it right, I thought it cleared its self. which is how I used it, which could have been the reason for the fails, since the cct would be back on before the voltage spikes and currents had fully settled. You do in fact have a delay which I didn't. This is probably why I ended up with a high speed TIG welder or arc lamp under the bonnet.

I think I will go with my idea of reducing the motor drive at the throttle point rather than chopping it and delaying its return, as you say loosing all drive, all of a sudden is not good if its not for a majorly good reason. As I mentioned before I have a second cct which is a timer, a sort of watchdog, that is held reset normally but if the current rises above trip point continuously (pulsing will reset it) for about 1.6secs then I really do loose all drive/power, its a master kill. 1.6sec is a long time to electronics but not when there might be a wall coming up.
These two ccts are completely autonomous and take no instructions from any source other than the current sensor.

I am using an HTFS800, the next one down available was a 200 and I did not realise at the time that they read a lot higher than the basic reading (the 800 will read up to 1200A) I thought 200A was the max for the 200.
Anyway they work the same, mine has the main negative cable going thro it and gives me a voltage of 3.18 at 500A.

[Nevyn]

I love testing! However, I love playing more! I need time to get it all mounted up. Time is in short supply.

http://www.youtube.com/watch?v=07DuTLBbStM

http://www.youtube.com/watch?v=bLSjMQGxftI

[duncan]

Hi Paul
Struggling with the simplest things
How/where do I buy the tape that goes under the MOSFETs and diodes?

[mora]

Digikey has lots of that material. Paul sent me this link when I asked about it few years ago.

ART03 ARI International Corporation | 509-1000-ND | DigiKey

Now if this monster link works:
Thermal - Pads, Sheets | Fans, Thermal Management | DigiKey

it should list you some alternatives. Most of them seem ridiculously expensive.

I used MICA pads. Ebay has lots of them for cheap. Those pads can be sliced in half to make them even thinner.

Pack of 10 to 247 18mm x 22mm Mica Insulator | eBay

I didn't use thermal grease with those even though that seller recommends it. I cleaned them well though.

[Roche]

Duncan, you might try "www pmb co nz" or "hiq co nz/plastic-components" (Replace spaces with dots) . Wiseman Electric Company in Wellington used to be quite good, but I think they have changed course rather...

[jackbauer]

Small update on the Re-Moc 1200. Got Adam's driver board assembled today and did some trial fitting of the busbars and c4de caps. Have decided upon 4 x 400v 380uf c4de caps. Two at each end of the igbt stack. Silly mouser only shipped 2 last week and I had to mess about with them to get the other two sent. Due tomorrow so hope to get working on the controller build seriously over the next week or two.