[jhuebner]

Originally Posted by JRoque

What language and target hardware do you code for? I'm doing mostly basic and assembler on Atmel chips with some dabbling on C. I believe the Tumanako open source project is C exclusively and might be a good reference - or you can lend a hand in their effort

Sorry JRoque, totally missed that question. I only code in C so far. As mentioned I'm still using a PC for sine Wave generation. Thus I wrote a C program on top of a linux kernel with the Xenomai real time patch.
I don't need to use lookup tables since the PC can probably calculate 1000 sine Waves during one PWM period.

Now I am indeed planning to join the Tumanako project. Their code is written in C/C++ and runs on an STM32 µC.

Yesterday I wanted to employ my redesigned IGBT contact board but it was mirrored So now I built a mechanical prototype that looks like that:


Of course the controller board is missing here because it simply non-existent

/Johannes

[JRoque]

Hey Johannes,

Now I am indeed planning to join the Tumanako project.

Yes I saw your introduction to the team, that's excellent news. To be honest I kinda felt they were cutting themselves short by using a prebuilt external IGBT pack, but I'm warning up to the idea now. I also didn't like the $595 price tag they put on the board the team is developing. That number seems high - and suspiciously Marketing-driven - for an open source project. I've participated in more than one "open source" project where after it was developed, the principals decide it's a good commercial product and split further development to their own branch leaving the open source lagging behind. Hopefully this is not the case here since some of us can really use it for our DIY projects.

Yesterday I wanted to employ my redesigned IGBT contact board but it was mirrored

You mean you didn't mirror the layer before routing it? If so, you have company on that corner. I must have done that so many times in my prototypes I lost count. Now I keep a steps list before I cut my proto boards and one of the steps is "mirror used bottom layers"

Do you route your own boards or is that chemically etched?

JR

[jhuebner]

Originally Posted by JRoque

Yes I saw your introduction to the team, that's excellent news. To be honest I kinda felt they were cutting themselves short by using a prebuilt external IGBT pack, but I'm warning up to the idea now. I also didn't like the $595 price tag they put on the board the team is developing. That number seems high - and suspiciously Marketing-driven - for an open source project. I've participated in more than one "open source" project where after it was developed, the principals decide it's a good commercial product and split further development to their own branch leaving the open source lagging behind. Hopefully this is not the case here since some of us can really use it for our DIY projects.

I'm not planning to buy any custom-built hardware for now. I picked up some board with an STM32 from work. Concerning the power stage I'll just use what I've got so far. I designed it with a lot of help from Semikron themselves so I think the chances are good for it to actually work.

Originally Posted by JRoque

You mean you didn't mirror the layer before routing it? If so, you have company on that corner. I must have done that so many times in my prototypes I lost count. Now I keep a steps list before I cut my proto boards and one of the steps is "mirror used bottom layers"

Yeah kinda like that Top and bottom line up perfectly but when putting it on top of the module it is "right side left".

Originally Posted by JRoque

Do you route your own boards or is that chemically etched?

Erm what? It's both I did the layout with a program called FreePCB, printed it on a photo-sensitive board and etched everything away that wasn't black.

/Johannes

[jhuebner]

Progress is slow but visible:



I've mounted IGBT and drivers to a large heatsink and am now driving it with an STM32 with the help of the Tumanako project. I've implemented a very simple sine Wave generator which I submitted to Tumanako.

It also looks like I'm close to cracking the current sensor issue with the help of the DRV401 IC. Tumanako has already implemented the field oriented control methods and is waiting for a suitable driver model to run it on.

I'm pretty optimistic that we'll have a working inverter soon, though not road legal...

/Johannes

[Automcdonough]

I'm a little worried about the board to IGBT connection not being physically stout enough, especially when you have more than 40A or so going through them. Probly won't happen with no load on the motor, but when you really put this to the test I think that will be the weak link.
Also 8 bit ought to be enough, it doesn't need to be silky smooth looking.

[JRoque]

Hi. Are you referring to the IGBT driver board? I'm not sure where you say there will be 40 amps. The driver board won't put out that much and the IGBT will likely switch 400 A. Typo maybe?

JR

[jhuebner]

Hi!

Heres a better picture:



The high current connections are made through the slugs that are screwed onto the board. The small wires are just used for driving the IGBT gates. Do you still think this connection could be overloaded? Oh BTW: theres just a 90A IGBT module beneath, so its not really high performance yet unless run at 800V or so

/Johannes

[Automcdonough]

Sorry I misunderstood what I was looking at, for some reason I thought you were intending to pump serious current through that control board!

[MPaulHolmes]

Awesome job, Johannes!!! You are the man. I can't wait to see you driving down the road with that sucker!

[jhuebner]

Thanks Paul



This weekend i learned my lesson about EMI. All the power cables were rather thin and I lacked an intermediate circuit capacity. As a result I was unable to read the motor shaft encoder because the MCU would count tons of spikes caused by the PWM. Voltage spikes on the DC bus would reach +-100V (at bus voltage of 80V and the motor idling)
As you can see, there are thicker cables now and a large capacitor. The voltage spikes have dropped to around +-5V and I can cleanly read the encoder. Well, sort of. I have to use the STM32s digital filter to get a clean count.
So, next I can implement a simple slip controller with the simple equation slip ~ torque (thats what it says in my text book)

/Johannes