Paul and Sabrina's Cheap 3 Phase Inverter (AC Controller) with Field Oriented Control

[CollinK]

Well, since there is renewed interest I'll post an update.

I have some preliminary hardware together and have done some testing today. I also took some video of my setup and how I've been testing. So far no motors have spun. Partly that's because all I have are huge motors and I don't want to start out initial testing with a 67kW monster.


All I have so far is the V/Hz code working. Yes, Paul had that working too but I've totally redone the V/Hz code. I'm having some weird issues with PWM at super low speed but it seems to be working at moderate to high speed. So, today I'll try to find a motor and test with the smallest one I can find. I also could convert the video and post some videos today or tomorrow.

Since things are getting very close with the V/Hz code I'll try to button it up and publish the link to the code very soon (today or tomorrow). Then other people can start messing with it too.

[energymiser]

Thanks Collink for your efforts. Looking forward to seeing how your testing goes. I don't think there is a lack of interest in this project. I haven't had anything to do with electronics for a long time and all I can do is watch from the sidelines and try to offer encouragement. I bought an oscilloscope the other day and am trying to get back in the game with some small projects but what really is motivating me is the electric vehicle. I don't think I am alone in being a "lurker".

Love to see the video. How have you mocked up the controller? Have you got a completed board? All the best.

Nigel

[CollinK]

Originally Posted by energymiser

Love to see the video. How have you mocked up the controller? Have you got a completed board? All the best.
Nigel

I breadboarded the main controller section.

My initial testing is complete. I've still got work to do but I did get a 5HP motor to spin. The motor was a 440V motor and I only had about 90V worth of batteries. 90V DC is equivalent to about 63V AC. So the motor wasn't exactly working very well but it did spin. I also tested with our mammoth 67kW motor. I blew up a driver during that... Whoops... Luckily it was just a gate driver and three diodes and the thing seems to work again.

While testing the 5HP motor all hardware was cool as a cucumber. There was no heating of the IGBTs at all (that I could tell). Everything was working perfectly on that front. It appears as if I'm getting basically no shoot through.

I'm working on a schematic to make a real controller board with more features like current sensing and all that good stuff. The breadboard version does use a hex not buffer so it's not as craptastic as it could be. You might notice that it looks like the dsPIC chip is missing from the breadboard. I messed up the schematic and did the wiring to the chip backwards... so I soldered the chip on the underside of the board. That sucked.

So, as promised, links to both the source code and the youtube video.

http://www.youtube.com/watch?v=HrzkB9l-aU4

revolt-ac-controller - Open ReVolt AC Motor Controller Firmware - Google Project Hosting

I'll keep working on things. Once I work the last few kinks out of the V/Hz code I'll get to work on FOC.

[energymiser]

Great work Collink. Its good to see motors spinning! Is that one of those Siemens water-cooled motors that were used in the US postal trucks? Are you designing your own controller from scratch or is this part of a collaboration between you electronic gurus to come up with a board that the lurkers can buy/build to run their own EV projects? I'm getting closer to being ready to mock up my own setup to play with but I would like to see more of a consensus on what features and components would make the most reliable and efficient controller that would be worth putting in a car. For me, a range of 100km. would make an EV a very useful vehicle and handle most people's daily driving needs.

[CollinK]

Originally Posted by energymiser

Is that one of those Siemens water-cooled motors that were used in the US postal trucks?

It is one of the Siemens motors from a Ford Ranger EV. It may well have been used in postal trucks too. It's a 1PV5133.

Are you designing your own controller from scratch or is this part of a collaboration between you electronic gurus to come up with a board that the lurkers can buy/build to run their own EV projects? I'm getting closer to being ready to mock up my own setup to play with but I would like to see more of a consensus on what features and components would make the most reliable and efficient controller that would be worth putting in a car. For me, a range of 100km. would make an EV a very useful vehicle and handle most people's daily driving needs.

Well... It's complicated... I am building my own controller from scratch for use in some commercial projects. But, what is or has been open will stay that way. The control software is open, the driver boards are open, and a reasonable control board will be open. Technically Paul had schematics of an earlier design for a control board posted. But, a lot has changed since then. I'm working on schematics and board layout for a newer design. It's based on the schematics which were posted before.

Past that I will be doing some proprietary stuff on top. So, there will certainly be things I'm not open sourcing but there will be plenty of things which are or will be. And, I'm only one piece of the puzzle. There are plenty of people who will hopefully continue the work toward a complete open source AC motor controller.

I think that commercial and open source interests aren't exclusive. I want something I can use and so do many other people. The best way to get there is to work together. In the end I get what I need (a good AC motor controller) and other people also get that same thing. We all win.

[sawickm]

Originally Posted by CollinK

The control software is open, the driver boards are open, and a reasonable control board will be open.

Are you referring to Powerex BG2A reference design PCB, and dual VLA500 Gate Driver PCB’s as open? Or are you going to design you own Gate Driver Interface? It would be nice to replace that Powerex stuff with a new low cost, open source Gate Driver Interface.

Technically Paul had schematics of an earlier design for a control board posted. But, a lot has changed since then.

Is this the base AC Controller Schematic you started with? https://www.onlinefilefolder.com/1sYLaUVLcWOoiL

I'm working on schematics and board layout for a newer design

Will it still be a dsPIC base AC Controller?

Keep up the good work

-Mark

[CollinK]

Originally Posted by sawickm

Are you referring to Powerex BG2A reference design PCB, and dual VLA500 Gate Driver PCB’s as open? Or are you going to design you own Gate Driver Interface? It would be nice to replace that Powerex stuff with a new low cost, open source Gate Driver Interface.

I think that either Paul or Mrbigh did some small modifications to the reference BG2A design but, yes, those boards. I know that the Powerex stuff is expensive ($43 per VLA500 board) but for my purposes that's OK. I suppose that's where the delineation between commercial and hobbyist becomes apparent. I'm dealing with a situation where it would seem to cost more time and effort to develop something custom and the VLA500 modules are cheap enough that it's not worth it. However, someone could, and maybe should, develop an open hardware driver. There's no reason that the control board could not still use the open drivers. The general layout of the VLA500 boards can be found in their documentation so an enterprising person could probably reverse engineer that and put discrete components on a board.

Is this the base AC Controller Schematic you started with? https://www.onlinefilefolder.com/1sYLaUVLcWOoiL

Yes, that's the one. Obviously that schematic was based on a totally different drive strategy. I don't think it ended up being a cheaper strategy however... At least not by much.

Will it still be a dsPIC base AC Controller?

Yes, in fact, since I already linked to the code, you could look at the code and see that it does indeed call for a dsPIC4011 chip. It will stay that way.

I accidentally ordered some dsPIC4012 chips and I'm thinking of using one of them on the board to do voltage readings of the 5V, 12V, 15V, and HV so that all the voltages can be monitored. I think that most people just use the cheapest PIC16 they can find to do this extra voltage monitoring but I'm also trying to build hybrid cars and might use the 4012 to do processing related to hybrid control. So, I'm likely to make my board have two dsPIC chips; a big 40 pin one, and a smaller 28 pin one. PIC chips aren't really a big expense anyway. Going with a second dsPIC instead of a PIC16 only is like a few bucks extra.

My goal is to put both processors on the canbus and have them both report what they know and listen for what they need.

[energymiser]

Hi Collink. Saw the video. Did you figure out why the big motor didn't want to go? I checked out the BG2A driver boards and Digikey wants $187 for a kit c/w 2 gate drivers. I am hoping to do better than that. I think I saw someone posted the schematic for the VLA500 gate driver, I'll keep looking.

I need to get started building something, so I will start with the driver boards. The parts price including the boards is where I'll start to see how much cheaper it can be done.

[energymiser]

I looked back in the thread for the gate driver schematic but didn't see a reference to it. Was I dreaming?

[CollinK]

Originally Posted by energymiser

Hi Collink. Saw the video. Did you figure out why the big motor didn't want to go?

I knew better than to try running the big motor but we did it anyway. The Siemens motor has like 0.1 to 0.2 ohm resistance windings. At start up there is no back EMF and so the windings will draw whatever your V/Winding R is. At the 100 volts I could supply that would equate to a start up current of 500 - 1000A. I had 200A surplus used IGBTs installed and no capacitor bank. This was not a smart idea. So, for future reference, don't try to start a motor with underpowered used transistors and no capacitor bank. I think that's why it rapidly went down hill. I've since rebuilt things (ack... I had blown two VLA500 boards, 1 IGBT module, 3 diodes, and one resistor) and I'm installing the capacitor bank and precharge system now.

I checked out the BG2A driver boards and Digikey wants $187 for a kit c/w 2 gate drivers. I am hoping to do better than that. I think I saw someone posted the schematic for the VLA500 gate driver, I'll keep looking.

I need to get started building something, so I will start with the driver boards. The parts price including the boards is where I'll start to see how much cheaper it can be done.

Mrbigh has the driver boards I was using in the video. He sells them for a very fair price. Ask him about it. I do have the schematic for the boards and I'm pretty sure I'd be allowed to post it. Could either Paul or Mrbigh confirm that?

BTW, the VLA modules are $43 a piece so 43 * 2 + like $5 in other parts plus the PCB from mrbigh and you are still looking at a little over $100 a driver board (and, obviously you need three). So count on like $350 for the driver section.