Paul & Sabrina's cheap DIY 144v motor controller

[jackbauer]

Programmer works. Managed to put some code together to flash an led (not exactly HAL9000 but hey its my first atmega program!).

[MPaulHolmes]

Good Job, Dave...

I'm going to try the software I sent you on a controller I just finished. I'll let you know what happens.

[drbobwoolery]

Paul, I made a much smaller approx. 0.2 milliohm shunt, appropriate for installation in the controller. If it is placed in the bus that is nearest the ground potential of the controller board, the common mode voltage will be minimized. This is often the expensive part of an instrumentation amplifier. Analog Devices and Burr Brown both make appropriate devices.

The current terminals on this one are the bronze bolts and contacts from a Metro solenoid. With 1/2 inch wide strip, and the sense leads silver soldered 1 cm apart, this should work well, and maybe fit where the toroid and Hall device are now.
If we like this design, we'll need a source of bronze 5/16 x 1 1/4 capscrews.
Or just break up a bunch of old starter solenoids.

[ga2500ev]

Originally Posted by bones007

I have a question about how the bootloader works. When you use the bootloader to re-program the microcontroller does your new code have to include the bootloader itself each time?

No. The bootloader is static.

Or is the bootloader protected somehow such that you can upload a program with flaws, fix the program and upload again without screwing up the bootloader.

It depends. With some controllers you can mark an area of memory as unwritable. An external programmer is used to load the bootloader into that area and then the memory is protected. In that instance virtually nothing programmatic will cause the bootloader to be overwritten.

If that's no available, then the backup is to have the bootloader software check to see where the target memory is located. If it's in the bootloader, then the bootloader won't overwrite itself. But there's nothing to prevent a loaded program from overwriting the bootloader in that case.

The bottom line is that without hardware memory protection, there is a chance that the bootloader can be overwritten. But in my experience, the advantage of not having to have an external programmer makes it worth the risk.

ga2500ev

[jackbauer]

The following takes place between 4pm and 5pm:

http://www.youtube.com/watch?v=5uwVp6l05UE

[MPaulHolmes]

The nice thing about the bootloader is that there is a CRC checksum built into the program, so that it will verify the software before turn on each time.

Hey Jack! That's interesting that it's oscillating like that on turn off. Some drivers that are dedicated to IGBTs actually set the gate to like -10v or something like that when turning it off. Mosfets I think don't much like that, but IGBTs don't mind. You could also try the "diode in series with the gate resistor" in parallel with the other gate resistor to speed up turn off. I'm mostly just worried about that LEM.

[squiggles]

The ringing at turn off may because it is switching to fast. It is also likely a source of electrical noise. Certainly worthy of investigation and research.

[MPaulHolmes]

If it's switching too fast, you can change R16 to maybe 4.7kOhm. I believe right now it's 6.8 kOhm. Or, you could increase R15 to 330 Ohm instead of 220 Ohm. Or make the gate resistors bigger. hehe.

[Mesuge]

Firstly, kudos to all participants in this awsome project.
Secondly, as there has been some talk about along the way upgrade options, is it possible to bump up the current design into 192VDC nominal (for 48V x 4 subpacks charging), I think it has been mentioned by Paul that by mosfet/diode/caps direct replacement "only" it can go as high as 180V @ 750A. I'd say the amperage is not that important criteria as max. voltage in this regard, as long as it still hovers around ~100kW peak, e.g. 192V @ 550A, thanks for giving it some thought.
Open source controller kits - Page 2 - DIY Electric Car Forums

[squiggles]

I suspect Jack's IGBTs will handle that comfortably. May have to review the capacitors though.