A question about inverter technology in air conditioners

[Wrichik Basu]

Recently, the inverter ACs have become quite famous. I got to know that in inverter ACs, the compressor is never actually switched off. The compressor speed is varied in accordance with the temperature of the room. This keeps the room temperature constant, unlike the previous technologies, where the compressor was switched on only when the room temperature went up a certain limit.

But one question was not answered: why call this technology "inverter"? Mainly, an inverter is anything that converts DC to AC, and the technology is used in power backups.

Is the naming of the technology used in air conditioners purely coincidental, or does it have something to do with inverters?

 

[anorlunda]

Good question. It is one way to make variable frequency drives so that the motor speed can be varied. The advantage is not just constant room temperature, but also more power efficient AC.

switch in accordance with the developed pattern and thus the output is obtained.

In refrigeration compressors[edit]
An inverter can be used to control the speed of the compressor motor to drive variable refrigerant flow in a refrigeration or air conditioning system to regulate system performance. Such installations are known as inverter compressors. Traditional methods of refrigeration regulation use single-speed compressors switched on and off periodically; inverter-equipped systems have a variable-frequency drive that control the speed of the motor and thus the compressor and cooling output. The variable-frequency AC from the inverter drives a brushless or induction motor, the speed of which is proportional to the frequency of the AC it is fed, so the compressor can be run at variable speeds—eliminating compressor stop-start cycles increases efficiency. A microcontroller typically monitors the temperature in the space to be cooled, and adjusts the speed of the compressor to maintain the desired temperature. The additional electronics and system hardware add cost to the equipment, but can result in substantial savings in operating costs.[8]

The DC refrigeration manufacturer for the unit on my boat told me an interesting story. He said, "On a boat, you hear every tiny sound. We made variable speed refrigerators that never cycle. But customers insisted that they must be broken because they didn't cycle. We had to go back to less efficient cycling."

 

[Wrichik Basu]

@anorlunda thanks for filling in the "missing link" in what I learnt.

 

[jim hardy]

Induction motors for appliances - that's become another little world of its own.
To save energy they've switched to three phase motors with variable frequency and variable voltage drive. They rectify line power then chop it into desired voltage and frequency, hence the term 'Inverter"
The motor control schemes are complex but with mass production not prohibitively expensive.
Two articles you might peruse
https://en.wikipedia.org/wiki/Vector_control_(motor)
http://www.ti.com/lit/an/bpra073/bpra073.pdf

If you're the type who rescues washing machine motors for workshop projects, stock up on old fashioned single phase ones while they're still available.

old jim

 

[Wrichik Basu]

If you're the type who rescues washing machine motors for workshop projects, stock up on old fashioned single phase ones while they're still available.

I always wanted to have a workshop of my own, where I can conduct my experiments without fear of damaging property. But sadly, there is no space in my house for one.

 

[jim hardy]

I always wanted to have a workshop of my own, ... But sadly, there is no space in my house for one.

This is great for apartment dwellers. It'll fold up and hide behind a door.

 

[Wrichik Basu]

This is great for apartment dwellers. It'll fold up and hide behind a door.

View attachment 225287

what is that called?

 

[jim hardy]

The one pictured is a Black & Decker Workmate. I've had one since about 1980 when i lived briefly in an apartment . There are several other brands with similar products . Some are flimsy so comparison shop.

 

[sophiecentaur]

<<Off topic stuff removed by moderator>>

Since the advent of brushless technology, things could be changing, both for DC and AC supplied motors. Induction motors have serious limitations, although they are extremely well suited to some applications.

 

[Wrichik Basu]

The one pictured is a Black & Decker Workmate. I've had one since about 1980 when i lived briefly in an apartment . There are several other brands with similar products . Some are flimsy so comparison shop.

Thanks for that. Let me see if I can buy it soon.

 

[sophiecentaur]

Thanks for that. Let me see if I can buy it soon.

Make sure that the rubber feet don't get lost. The naked ends of the legs can chew up your best living room carpet. The positive thing is that the coffee table no longer needs to be used as a sawing horse.