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

[thingstodo]

Originally Posted by MPaulHolmes

Hey! We could have a contest to see which spins the motor post faster. The one that spins it the fastest is making better use of the fixed Id and Iq!

First, we need to determine your motor's stator and rotor inductance, and a stator coil resistance. In my case, it works fine to just use the same rotor inductance as stator inductance. To figure out the stator inductance, we have to run a test and measure the offset of 2 waveforms. I'll set it up, and make sure it's working on my end before sending it over to you so you don't get stuck with a crappy hex file.

Looking forward to it! Once the sensorless code is spinning the motor, I've GOT to get some video posted!

[thingstodo]

Originally Posted by MPaulHolmes

I'll get a hex file to you, and you can try out the sensorless code. although, I haven't actually used the sensorless to drive the motor yet. I was just trying to verify that I could obtain the rotor flux angle from the back emf angle somehow. It looks like you just subtract off like 20% of a period, but I think I remember someone saying that it's actually 90 degrees offset, so maybe my sensored rotor flux angle is off by a few %?

Is it time for me to couple the DC motor to the AC motor again?

I have a hand-held tachometer to check rpm, and you know what rpm the motor is turning .. so we should not overspeed the DC motor .. right?

[MPaulHolmes]

I'll set the RPM limit to 4000 like you were saying so you don't have to worry about the DC motor. We have a nonfunctioning encoder right? I'll make sure it can start up without using the encoder. If it can't we'll have to start up with some other way and once it gets to the blazing speed of 1.5 Hz we can switch over haha.

[e*clipse]

Originally Posted by MPaulHolmes

I'll set the RPM limit to 4000 like you were saying so you don't have to worry about the DC motor. We have a nonfunctioning encoder right? I'll make sure it can start up without using the encoder. If it can't we'll have to start up with some other way and once it gets to the blazing speed of 1.5 Hz we can switch over haha.

LOL! When I made my first machine shop, in a garage w/ a friend, we had a phase converter that we "kick started."

[thingstodo]

Originally Posted by MPaulHolmes

I'll set the RPM limit to 4000 like you were saying so you don't have to worry about the DC motor. We have a nonfunctioning encoder right? I'll make sure it can start up without using the encoder. If it can't we'll have to start up with some other way and once it gets to the blazing speed of 1.5 Hz we can switch over haha.

I will work on getting the DC and AC motors coupled, aligned, etc.

If you need an encoder signal, I can use the 64 ppm encoder built into the AC motor.

And if that doesn't work, I'll boost the AC motor with the DC motor. The DC motor turns at about 300 rpm when connected to a 12V car battery.

[MPaulHolmes]

I had to abandon a particular approach for the sensorless, and now have a new way that is more direct, and eliminates the need for information about the rotor inductance and mutual inductance. The other way would work as long as the rotor flux angle was being set with the sensored code, but wouldn't work for very long when it would switch over to sensorless. I hope this approach works. It is much simpler, and I think it will work, and will be easy to tweak if necessary. I probably wont be able to test it today since my son has a fever and I'm getting him a regular supply of pedialytes. Once it's working I'll send over a hex file. One neat thing about it is the super fast __arctan() that I made. TI said this approach was not good since the arctan takes so long to compute. haha

[Thalass]

I hope your boy gets well soon!

[MPaulHolmes]

Thanks! Me too. Liquid tylenol is only helping a tiny bit. It just came out of nowhere. We went to the park yesterday, and there were a ton of fish in a lake, so we were feeding them to draw them to the surface, then I reached in really fast and scooped out 2 of them, but they all had back spikes, and it stabbed my hand and it was bleeding, but at least we got some extra protein for our chickens. haha. Oh all of that to say that I don't know why he's sick. haha

[thingstodo]

Originally Posted by MPaulHolmes

I had to abandon a particular approach for the sensorless, and now have a new way that is more direct, and eliminates the need for information about the rotor inductance and mutual inductance. The other way would work as long as the rotor flux angle was being set with the sensored code, but wouldn't work for very long when it would switch over to sensorless. I hope this approach works. It is much simpler, and I think it will work, and will be easy to tweak if necessary. I probably wont be able to test it today since my son has a fever and I'm getting him a regular supply of pedialytes. Once it's working I'll send over a hex file. One neat thing about it is the super fast __arctan() that I made. TI said this approach was not good since the arctan takes so long to compute. haha

Sorry to hear about your son ..

So you can figure out what voltage and what angle to use ... WITHOUT knowing rotor inductance or mutual inductance ...

And the method uses arctan ...

OK - where can I read about THIS method?

As for the new HEX file, I won't be set up for testing until I get the AC and DC motors mounted on a solid base. I got NOTHING done this weekend.

[MPaulHolmes]

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