Author Topic: Inverter project - looking for revision  (Read 1077 times)

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Offline TreeOoneTopic starter

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  • Country: hr
Inverter project - looking for revision
« on: March 05, 2019, 09:57:47 am »
Hello everyone!

I've decided to build a 3-phase inverter with input power factor correction circuit (PFC). This small project got a little complicated on the way....

My inverter should draw power from local utility grid 1-phase 230Vrms / 50Hz, then rectified it and step it up to approximately 565Vpeak. Finally, use this DC voltage to create 3-phase output 400Vrms / 50Hz.

I would like to supply small sized 3-phase motor. The idea is to draw 10Arms maximum from utility grid (with power factor close to 1), which equals 2,3kW, and pass it to my 3-phase motor (which equals 3,3Arms per phase, not including reactive energy, so actual current should be maybe 6Arms, or 8,5 Apeak).

Now, since I would like to monitor operation of my inverter, I've decided to measure some values:
a) PFC input circuit:
a1) grid rectified voltage
a2) PFC inductor current
a3) output DC voltage
b) 3-phase motor circuit
b1) current in all motor phases

I plan to utilize NUCLEO-F767ZI or NUCLEO-H743ZI for control purposes, which will connect to designed PCB via pin header connectors (i.e. MCU will not be part of PCB itself).

I've drawn my inverter in KiCad (attached below), and as it turns out, the most complicated thing so far are conversions from analog to digital domain, involving multiple op-amps, opto-couplers and similar exotic beasts. (I am aware that MCU programming is another complicated task, but that one is in virtual domain where errors can be easily fixed.)

Since I don't have lots (any  :-\) of experience (so far I've managed to persuade Arduino Uno to blink a few LEDs and turn on one stepper motor) I would like to ask the community for some help.

Can somebody take a look at my drawing, particularly at those nasty op-amps and opto-couplers, with protection diodes and give his/her opinion on this matter.  So far I have invested two months in research, and at this moment everything looks OK, but due to my lack of experience, I would like to hear some unbiased opinions.

All comments are welcomed!  :)
 


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