# DC Inverter mini split



## WyrTwister (Jul 20, 2013)

My mini split is the traditional technology , bottom of the line 13 seer el cheap o model . The condenser cycles , off and on , with cooling load / demand .
I read of the newer technology with DC Inverter drive for the compressor . I read of 380 VDC powering the motor ?
Now , we have wired quite a few 3 phase AC VFD's for various application . Largely HVAC .
I watched a youtube video by a guy " Down Under " that seemed to imply the mini split inverter drive compressors were 3 phase ?
I am aware that the VFD's I am familiar with , convert the AC to DC . The " slices & dices " the DC to produce " synthetic AC of the frequency , voltage and amperage to run the motor in question .
In theory , would not matter if the incoming AC is single phase or three phase .
So , am I getting close to the truth of the matter ? Are the inverter drive mini split compressors actually three phase AC ? Never heard of three phase DC , do not personally think it exists . Certainly not by the definition of three phase I learned . MANY years ago . Would think it would make Tesla spin in his grave .
Wonder if he would spin CW or CCW ? 
God bless
Wyr


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## ductlessaire (Nov 26, 2013)

Most of your variable speed drives are dc voltage Trane and carrier Have been using that technology for years. With AC it works like a light dimmer the further up the coil you get the more resistance and the less amps allowed to be pulled from your load. That works fine with light bulbs but if you do it with motors it will not last very long ( burnt winding) With DC you can actually increase and decrease the voltage to the motor and allow it to spin faster and slower.. And as far as the you 13 seer mini split .. look at the saving on a 20 seer 12000 btu vs a 13 seer not even 1 amp most less than that . If your lucky and that would only be on low speed. I find the more drives and control boards in a system. The more likely you are to have a failure.. Don't knock that 13 seer Machine just because a high paid writer made a influencing article in a high paid advertising ad .Trying to promote a machine that will cost you twice as much and save you 2 as less. Just My 2 cents worth


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