Inverter Compressor

Picture driving through the city and slamming the gas and brake at every red light. Your fuel disappears fast. On the highway, where you hold a smooth, steady speed, you use far less gas.

Inside an appliance, the part that squeezes refrigerant (a special fluid that carries heat) to make cold is called the compressor. Older fixed-speed motors had only two settings: 100% power or 0%. When the room got warm, the motor roared on at full blast. When the room cooled, it shut off completely. Then it repeated that cycle over and over.

An inverter compressor works more like a car's accelerator, changing speed freely. When you first turn it on, the motor spins fast to cool the room quickly. Once the room hits the target temperature, it usually doesn't stop. It keeps turning gently at very low power. (If it's cool outside and you need very little cooling, it may pause briefly and then start again.)

This cuts out wasteful stop-and-restart moments. At low speed, the motor also doesn't have to squeeze the refrigerant as hard, so it makes the same cold air with less power. That's why inverters can save a lot more electricity than fixed-speed units. The temperature also swings less, so the room stays comfortable.

The power from a household wall outlet in Korea (as in the US) is alternating current (AC) that waves back and forth 60 times per second, so its direction flips 120 times. If you feed that straight into an ordinary motor, the motor can only spin at one fixed speed.

An inverter is a kind of magic converter that rewrites the rhythm of that electrical wave. It first turns the AC from the outlet into smooth direct current (DC). Then it fine-tunes the electricity's frequency and sends it on to the motor.

Send a higher frequency and the motor spins fast and strong. Send a lower frequency and it spins slowly. The inverter changes the frequency it supplies over a wide range, so the compressor can run anywhere from low speed to high speed. A controller keeps calculating the room temperature and tells the motor exactly how fast to turn.

Thanks to this, the pressure on the refrigerant can be controlled precisely. And with fewer stops and restarts, there's less strain on the parts.

Many people think switching off the AC when they step out is a smart way to cut the power bill. But with an inverter AC, many explanations say that leaving it on during a short outing can use less electricity. How many minutes counts as "short" depends on your insulation, the outdoor temperature, and the size of the room, so there's no single rule.

The biggest power draw comes when the motor goes all out from a standing start to cool a hot room. Once the room is already cool, the motor drops into low-speed maintenance mode and uses far less power than at full output.

When you come home, the power it takes to run the motor at full blast to cool the heated-up room again can be more than the power it would have used running gently while you were out. That's why switching it off and on again at short intervals tends to backfire.

One catch: if a window or door is open and hot outside air keeps flowing in, even an inverter has to run at full output with no rest. To get the real savings from an inverter, keep the room well insulated and sealed so the cool air doesn't leak out.