Variable Frequency Drive for a larger factory fan

[chy_farm]

Last year we had a very hot Summer and Autumn so had a presumption that we should need a very big fan in our shed to get our job easier this year.
This motivation gave me a way to build a single phase Variable Frequency Drive for a bigger fan motor!

Fortunately or unfortunately we have cool Summer now, so not yet get a new big fan yet, nor have a chance to run this VFD...

[chy_farm]

Inside: Triangle and rectangle generators are analogue unit.

[chy_farm]

Started from these;






Making shifts to the frequency is to be done with a couple of white dials, an obsolete analogue way.




Chy

[chy_farm]

But on the way of assembling I found this handmade case was a tad small, so added some more rooms ;



Main power board with magnetic contactor and a transformer;


Placed a noise filter right after the main contactor;


Temperature sensors are placed onto five different part,
1: Bridge diode (50A),
2: Short cut unit,
3: Isolated Gate Bipolar Transistor unit,
4: High speed diodes for return current re-circulation unit,
5: Double 2mH filter coils right before the output terminal;


Output frequency monitor;


Output current monitor, and its detector (HAS-50);




Chy

[chy_farm]

Schematic for power units is;


Chy

please note there may be a wrong design in above drawing.

[chy_farm]

A couple of logic units of this type is known as noise-fragile to electro-magnetic noises. This part was one of the complexities to me.


Units in the right half (marked yellow) are electrically shielded with copper plate around them, they are a triangle wave generator and a wave form comparator, and a sine wave generator.

These in the left half are also shielded with so called shield wire (black wires), they make up a Pulse Width Modulation logic unit.

Chy

[nova_robotics]

That's great. Well done.

Why three Arduinos?

[chy_farm]

Good morning Nova, Why? ,,, only because I did not know other ways, lol. Do you make them in one Uno?
Chy

p.s. Glad to know you are a specialist of robotics, Nova!

[chy_farm]

The logic unit needs a delay-time-unit for one of the safety purposes;

This unit is not yet given the noise shield.

The delays are confirmed with oscilloscope views;



Chy

[trigger]

Does the breadboard not contribute to rf noise ?Once the design goes to PCB there should not be so much interference.