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

[thingstodo]

Originally Posted by shaggythegangsta

Thanks sir, i found that also on web but seems to be old or not?
and there is are no hardware (schematics) files...

it will be very helpful to have latest files on first post

The latest files I have are from Jan 3, 2017. I tried to include the .sch and .pcb files below, but they are too large. 374K zipped.

It might take a couple of days for wehzeh or paul to log in, but maybe it's best to get the files posted to git so that everyone is working from the same files.

[shaggythegangsta]

Originally Posted by thingstodo

The latest files I have are from Jan 3, 2017. I tried to include the .sch and .pcb files below, but they are too large. 374K zipped.

It might take a couple of days for wehzeh or paul to log in, but maybe it's best to get the files posted to git so that everyone is working from the same files.

thanks sir no problem i will wait..
i would be a nice thing to have all updates on github..

[thingstodo]

Just a nudge to see if wehzeh or paul have checked in

[MPaulHolmes]

Hello! I can't change the first post, since it's too old. Sorry I wasn't on here sooner. We would have to beg the administrator. I am so confused by the github thing. I can never figure out how to do it other than destroying what once was, and putting in the new code. But now that there's a new board, I can't use that old technique.

[thingstodo]

Originally Posted by MPaulHolmes

I can't change the first post, since it's too old. Sorry I wasn't on here sooner. We would have to beg the administrator.

I guess we'll have to beg an administrator ... 'cause it would be *SO GREAT*

I am so confused by the github thing. I can never figure out how to do it other than destroying what once was, and putting in the new code. But now that there's a new board, I can't use that old technique.

Wehzeh - can you help? I can log into github and submit the files I have .. if you tell me where to put them?

[MPaulHolmes]

I used one of the AC control/driver boards to make a 240v/120v split phase inverter, so that there are 2 120v supplies, and a neutral. The 2 120v supplies are 180 degrees out of phase, so you can use the 2 hots to make the 240vAC. I finally got it working well with the newly configured MPPT just last night. So, now I have the solar panels putting out between 380v and 450vDC, and that goes to the MPPT, which charges 28 (just the number I had laying around!) 7amp*hr 12v batteries, which are all in series. Then, the 28 batteries feed the input of the split phase inverter, and now I'm using that to power my house! Finally I can run both 120v and 240v stuff from the same inverter. And it's 100amp 240v service! Well, I can do 200amp surges. The hardware overcurrent is set to 200amp.

Josiah is going to help me do a nice video of the whole setup. He's been practicing his lighting, and has been acting as my apprentice lately.

Oh, and you can just change one little setting, and boom, you have 3 phase power at your house! 208v 3 phase up to 480v 3 phase.

[thingstodo]

Originally Posted by MPaulHolmes

I used one of the AC control/driver boards to make a 240v/120v split phase inverter, so that there are 2 120v supplies, and a neutral. The 2 120v supplies are 180 degrees out of phase, so you can use the 2 hots to make the 240vAC.

This is GREAT news! Looking forward to seeing that code!

Does the inverter deal with the current surge drawn by an induction motor starting up, like an air conditioner, or a water pump?

It may make sense to have an option for soft start, where the inverter ramps up from 0.5 Hz to 60 Hz in 2 - 5 seconds to avoid that 5 to 10 times rated current surge from a single connected motor.

Oh, and you can just change one little setting, and boom, you have 3 phase power at your house! 208v 3 phase up to 480v 3 phase.

YET MORE AWESOME PROGRESS!

I just happen to have a 30 HP, 575V, 3 phase motor that I can use to stress the startup of a 3 phase 'supply'.

Sounds like I will have to start working on connecting the 2 AC Controller boards that I have. I really want to get the split phase output working at a 48V buss so that I can run a sump pump in the spring ... using a golf cart as the power supply. I will try running at 60 Hz, but I doubt that the motor on the sump pump will operate properly at the lower voltage ... I guess I'll see ...


Assuming that I get any of this done ..

[MPaulHolmes]

The soft start is a good idea. Right now I was just ramping up voltage at startup, but I didn't ramp up frequency too.

[oil pan 4]

I have been studying and testing soft starting single phase motors.
The only way to soft start a single phase motor with a load attached using constant frequency power is to reduce starting voltage down to around 220v with a transformer then quickly ramp up to full 240+ volts.
Using this sequence on an air compressor with an auto transformer I was able reduce starting amps by about 20%.
The only way to soft start a single phase motor on constant frequency is to completely unload it, resistor or transformer start with a clutch to engage the load after the motor is up to speed.

If you can reduce frequency and voltage you will likely have much better results starting the motor with load than I did.
But you have to get the motor up to speed quickly or the start circuit will burn up.

[thingstodo]

Originally Posted by oil pan 4

I have been studying and testing soft starting single phase motors.

Thanks for sharing - I am just making assumptions so far

The only way to soft start a single phase motor with a load attached using constant frequency power is to reduce starting voltage down to around 220v with a transformer then quickly ramp up to full 240+ volts.
Using this sequence on an air compressor with an auto transformer I was able reduce starting amps by about 20%.

My load is a centrifugal pump, so it does not have a lot of load on start. There is not much water moving until you hit 30 - 35 Hz. I'm more concerned with the startup current that the motor wants, with a slip of 1800 rpm to begin with instead of maybe 60 rpm at running speed.

I am hoping that I can start at about 0.5 Hz .. since that seems to be where all of my VFDs start for some reason .. and ramp up to 60 Hz in the 2 - 5 second range. The capacitor start that is part of the sump pump will still shift the phase, I hope, and give some starting torque. But the speed switch (I think that is what deactivates the capacitor start) should switch the circuit to 'normal' single phase induction motor after maybe 20 Hz?

At a buss voltage of only 48V on a lead acid pack, I may not be able to run the sump pump at 60 Hz. But I need to get at least high enough to disengage the capacitor start, and to actually move some water. And of course I need to limit the current on the motor to the full load amps. It will be interesting, and I will no doubt learn (or perhaps re-learn) some stuff. And I will be using a sump pump that has bad seals and that overheats from previous abuse ... so if I mess it up, it's not much of a loss ....