TheBackShed.com

Forum Index : Electronics : Power factor correction

Author

Message

stockleys
Regular Member

Joined: 21/06/2019
Location: United Kingdom
Posts: 54

Posted: 01:19pm 25 Jul 2019

Copy link to clipboard

Print this post

Is it possible to add passive pf correction to an inverter?
I only ask as when running my refrigerator, my meter shows a pf of 0.7
And as I understand it, I would be using less dc current if this pf was 1.0

Is this correct?

Would a simple pf cap wired directly to the ac out, cause any problems?

My inverter is a 3000w high frequency inverter. (Yes I k ow, you all like your low frequency inverters but this is what I have and what works for me)

CaptainBoing

Guru

Joined: 07/09/2016
Location: United Kingdom
Posts: 2075

Posted: 01:28pm 25 Jul 2019

Copy link to clipboard

Print this post

does this help?

I would strongly advise against guessing

https://www.rapidtables.com/calc/electric/power-factor-calculator.html

https://duckduckgo.com/?q=online+power+factor+correction+circuit+schematic&atb=v158-1&iax=images&ia=images&iai=http%3A%2 F%2Fsecure.tutorsglobe.com%2FCMSImages%2F1492_16.2.jpg

stockleys
Regular Member

Joined: 21/06/2019
Location: United Kingdom
Posts: 54

Posted: 01:59pm 25 Jul 2019

Copy link to clipboard

Print this post

I�m guessing you mean not to guess on the size of capacitor

I�m thinking the cap on my refrigerator is on its way out.
If it was in good working order, would this aid with startup current?
If I have my tv on (110w). And the refrigerator kicks in (78w running 800w surge), the inverter cuts out. Then restarts itself. Yet I can run the kettle 2kw and the tv at the same time. When the kettle and tv are running, the pf is 0.96.

Not knowing the full ins and outs of pf. This is the only thing I can think of to prevent the shutdown. And to save power in the batteries (not huge problem this time of year

tinyt
Guru

Joined: 12/11/2017
Location: United States
Posts: 438

Posted: 05:38pm 25 Jul 2019

Copy link to clipboard

Print this post

I am assuming your HF inverter has a DC boost converter (Battery voltage to 400vdc?)

Not sure if this hack will work. It will need a lot of work. You might also need a back-up inverter in case your inverter blows up. I hope this will not happen.

Add more capacitance to the 400vdc filter. Carefully adjust overload time constant for it to ride thru the surge.

This might need some reverse engineering with no guarantee of a successful outcome.

Warpspeed
Guru

Joined: 09/08/2007
Location: Australia
Posts: 4406

Posted: 10:30pm 25 Jul 2019

Copy link to clipboard

Print this post

If your inverter is completely bi-directional for power flow, reactive loads are no problem at all, and adding PF correction is a complicated waste of time.

Oz inverters, Mad-inveters, and Warpverters are all fully bi-directional and can easily handle a large out of phase current flow. Its the low cost light duty high frequency type of inverters that usually go bang from reactive loads.

Cheers, �Tony.

Print this page

To reply to this topic, you need to log in.