Mini Split Inverter Explained – What is Inverter Technology

The word Inverter is used repetitively in many mini split marketing materials, for example, in their catalog, in the product titles of Amazon, Home Depot, Lowe’s and other stores. It looks like inverter is a key feature of mini split. So, what inverter means and why is it so important to mini splits?

In short, inverter is a technology that enables the otherwise fixed-speed compressor to change its rotational speed. It utilizes various electronic components arranged in a specific way to manipulate the electrical frequency output to the compressor, thereby regulating the capacity of the mini split.

It is no exaggeration to say that inverter is what made mini split so successful in achieving high energy efficiency, quiet operation and superb comfort. Let’s look at how this great invention works and how you can benefit from it.

Fun fact: Toshiba was the first to introduce inverter residential air conditioners back in 1981. In the United States, Toshiba partnered with Carrier to launch their ductless mini split products.

How Inverter Works in Mini Split?

In mini split, inverter is an electronic control board known as an inverter PCB (stands for printed circuit board) or an inverter P.C. board. It is located inside the outdoor unit.

As a whole, the inverter PCB converts the incoming power supply in alternating current (AC) to direct current (DC) and then back to alternative current (AC) to power the compressor.

When the power is being converted from DC to AC, the inverter can change the frequency of the output AC and by doing so, the speed and therefore, the capacity of the compressor can be controlled.

To regulate the capacity, a frequency control is needed. The inverter makes it possible to control the rotation speed of the compressor.” – by Daikin

In the United States, power is supplied at 60 Hz. Inverter mini splits control their capacity by increasing or decreasing the power frequency to their compressor by 2 Hz every second until it reaches the setpoint.

When you turn on the mini split, the inverter will send power at 60 Hz to the compressor which enables the mini split to operate at full capacity. Once the room temperature drops to the setpoint (what you set on the remote controller), the inverter will gradually reduce the Hz to a point where it can maintain your room temperature consistently.

Inverter Mini Split vs Normal Mini Split

In the United States, almost all mini splits sold are inverter mini splits. However, outside the United States, there are plenty of non-inverter or the so-called normal mini splits.

One of the reasons why normal mini splits are not sold in certain regions may be very well due to high energy efficiency standards. According to Daikin, inverter air conditioners save up to 58% of energy compared to non-inverter air conditioners.

For comparison purposes, normal mini splits are just like traditional non-variable-speed central air conditioning units. A very obvious characteristic of a non-inverter air conditioner is the compressor will kick in/out, turning on and off several times a day.

Contrarily, variable-speed air conditioners or inverter air conditioners don’t stop their compressor. Instead, as explained earlier, they reduce the compressor speed and maintain it. So, you can easily spot an inverter air conditioner if you notice the compressor never turns off.

From the outside, inverter mini splits look exactly the same as normal non-inverter mini splits. Maybe except if there is an energy sticker, the non-inverter ones will have a much lower number/rating.

Pros & Cons of Inverter Mini Split

Inverter and non-inverter air conditioners are widely sold in the world. While inverter technology offers many benefits, it also has its downsides. That’s why plenty of air conditioners out there are non-inverter.

The pros of inverter mini splits are as follows:

• Higher Energy Efficiency – Inverter mini splits don’t stop their compressor. Hence, a lot of energy is saved when they don’t have to kick-start the compressor several times a day.
• Better Comfort – Inverter mini splits are capable of keeping the room temperature consistent, unlike non-inverter mini splits where the temperature fluctuation can go up to ±2°F.

The cons of inverter mini splits are as follows:

• Higher Cost – Outside the United States, non-inverter air conditioners are typically 30% cheaper than inverter air conditioners. Furthermore, inverter air conditioners have an extra inverter PCB and require an additional signal wire to connect the indoor and outdoor units.
• Reliability Issue – Inverter air conditioners are more prone to PCB failure due to the fact that they have one. Additionally, a power surge can also risk damaging the PCB.

Summary

In summary, inverter mini splits are an energy-efficient type of air conditioner that is capable of controlling their capacity. The inverter located at the outdoor unit changes the electrical frequency output to the compressor, thereby changing the rotational speed of the compressor and achieving capacity control.

Inverter technology, the inverter PCB and inverter-driven compressors today are very mature. They are replacing non-inverter air conditioners every year due to the fact that they use less energy and therefore, better in terms of cost savings and sustainability.

So, no need to worry about the reliability issue. All manufacturers provide a warranty for their inverter drives and inverter compressors.