Inverter air conditioners

Inverter air conditioners

Introduction

To understand DC Inverter ACs, we first need to understand how they work. Air conditioners use a refrigerant (a gas which exists in low pressure but turns liquid as the pressure increases), which is compressed and liquefied by the compressor. It is then cooled down in the condenser and later allowed to expand (become a gas) in the evaporator, albeit in a controlled manner. Those who have studied physics, would know that this expansion causes a cooling effect which, in turn, causing the condenser to become warm.

The same principle is used in refrigerators; they move the heat from the inside to the outside. When an AC is in cooling mode, the heat from the room is removed and pushed towards the outdoor unit of the split AC. If the AC has the ability to heat, it can reverse the process, the energy is absorbed from the outside while heating the room. In most cases, the reverse process, i.e. heating mode, consumes less power than the cooling mode because the compression energy is added to the overall heating cycle.

The remaining two important components of an AC are its motored fans. The outdoor fan chucks the air out of the condenser to the outside. However, the indoor unit makes use of the blower and louvers/fins to dissipate the cool air (or hot air if the AC is in heating mode) to the room.

Until a few years ago every single air conditioner unit was those of stable speed when we switched on our unit with a remote or wired remote our unit began to run and it worked at its full power, at its 100% of capacity, when it reached to the adjustable temperature or when we stopped it manually, the unit “stopped” completely and it didn’t keep throwing cold or heat (heat pump),the air conditioner stable speed units only have 2 speeds (0% and 100%) and when you start them they pass from being completely stopped to be at their full capacity because they give their maximum capacity right after switching on them. That’s the reason we could feel in the intensity of current of our house or office creating in many occasions a lowering in the light intensity of our room, dining hall, etc. It was noticed like the bulb didn’t give off much light just when you switched on the air conditioner (voltage descent) due to the big energy consumption the unit needs to pass from 0% to 100%, later the situation was settled and there weren’t more intensity descents (until the next starting), that’s why after starting the unit directly to 100% of its nominal capacity and maintain itself through all time the unit was running, we noticed that feeling of an intense cold so many people miss, the inverter air conditioner units don’t work this way, because these begin running slowly and then they accelerate to its full capacity reaching a 140% of its nominal capacity, but after reaching the desired temperature the unit scales down the power used and operates at much lower power  levels .

Non-Inverter Air Conditioners

Non inverter or fixed speed air conditioners operate on a fixed amount of power at a fixed speed. This means the compressor has to stop and start again to maintain the desired room temperature..In this type of arrangement the compressor is either off or on. When it is on, it works at full capacity consuming full electricity. When the thermostat reaches the required temperature setting, the compressor stops and the fan continues to function. When the thermostat senses that the temperature in the room has fluctuated, the compressor starts again.

Inverter Air Conditioners

This technology was developed in Japan and is now being used globally for air conditioners and refrigerators alike. In inverter air conditioning systems, the speed of the compressor varies to ensure energy efficient operations and precise cooling or heating as required.

A DC inverter converts AC current to DC current. It then uses a modulation technique (called Pulse Width Modulation) in another inverter to produce AC current based on the desired frequency and voltage. The variable frequency AC drives the brushless motor or induction motor. The speed of the motor is proportional to frequency of the new AC voltage. Thanks to this, the compressor can now run at multiple speeds.

The inverter technology acts like an accelerator in a car. When the compressor requires more power, it gives it more power. When it needs less power, it provides less power. In this kind of setting, the compressor is always turned on, but draws less power or more depending on the temperature of the incoming air and the setting adjusted in the thermostat. The speed and power of the compressor is also adjusted accordingly.

Major difference between the two

An air conditioner with DC inverter technology has the ability to control its cooling (or heat) transfer rate by changing the output from its compressor. The rate can be modified depending on the requirements of the room. To put it more simply, the AC uses electricity depending on the environment’s requirements.

The compressor in a common AC runs at full 100 percent all the time. When it is not needed it shuts off. So a common AC uses start/stop cycles to control the temperature.

When using a DC Inverter in an air conditioner, it uses a processor to check the surrounding temperature and adjusts the speed (power input) of the compressor based on it. It can provide different levels of cooling or heating. So the DC Inverter AC regulates its output capacity to uniformly control the temperature of the room.

Both the inverter and non-inverter systems offer similar functions but differ in terms of compressor motor type running in the system. The compressor is responsible for compressing the refrigerant into liquid after which it shuts off and allows it to expand. As this process takes place, the refrigerant begins to cool thus producing the desired effect of cooling. Inverter air conditioner units are designed in such a way that they save up to 30-50% of electricity units consumed as compared to a regular air conditioner.

The magnitude of cooling or heating required by an air conditioning unit varies depending upon the outdoor temperature and the amount of heat in the room. When the cooling or heating effect needs to be amplified, the compressor will operate at a higher speed and will upsurge the amount of refrigerant flow.

On the contrary, during moderate outside temperatures for example, when the cooling and heating capacity needs to be reduced, the compressor will run at a low speed and will decrease the amount of refrigerant flow. When the inverter air conditioner is switched on, the compressor operates at a high speed in order to cool or heat the area rapidly. As room temperature approaches the desired temperature, the compressor slows down, maintaining a constant temperature. Any spontaneous fluctuation in the room temperature will be detected and promptly adjusted to bring the room temperature back to the set temperature.

There are many benefits of the inverter ac First of all, it requires less electricity in comparison to traditional air conditioning unit. And the other benefit is that it comes with a compressed circuit board that is able to handle various cooling loads. You will not get this feature in the non-inverter air conditioners. Moreover, the traditional type of air conditioner or non-inverter type of air conditioner offers less cooling than the inverter ac. Inverter ac is not prone to voltage fluctuations like the traditional one. It is durable and requires less maintenance than the non-inverter type of air conditioners.

                         
The inverter type ac is energy efficient. This is one of the key features of this air conditioner. It consumes around thirty percent less electricity in comparison to the traditional and non-inverter type air conditioners. In this developed system, you do not need to keep the system on and off to get the required temperature. It comes with an automatic system that makes necessary adjustments to maintain temperature

Operating principles

The Inverter technology   is the latest evolution of technology concerning the electro motors of the compressors. An Inverter is used to control the speed of the compressor motor, so as to continuously regulate the temperature. The DC Inverter units have a variable-frequency drive that comprises an adjustable electrical inverter to control the speed of the electromotor, which means the compressor and the cooling / heating output. The drive converts the incoming AC current to DC and then through a modulation in an electrical inverter produces current of desired frequency. A microcontroller can sample each ambient air temperature and adjust accordingly the speed of the compressor.. The biggest difference between inverter and non-inverter AC is the fact that the motor of the inverter compressor has a variable speed. The speed of the non-inverter compressor is fixed. This means that it operates either at full or minimum speed. A censor in the inverter adjusts the power according to the temperature in the room, lowering the electrical consumption and saving energy.

Efficiency and Operating cost

The inverter air conditioning units have increased efficiency in comparison to traditional air conditioners. A conventional AC starts multiple times and always runs at peak capacity. This means that every time it starts it needs extra electricity to jump start its stationary motors and compressor, i.e. torque current. Without being too technical, you can think of it this way, it needs more power when it starts and it starts too many times. It also runs at full capacity each time requiring a lot of current.

In comparison, a DC Inverter AC never turns off its compressor or motors. It reduces the electricity it needs and constantly keeps cooling (or heating) the room. When it does start the first time, a DC Inverter AC starts off slowly so it doesn’t require a massive torque current. Inverter ACs can start at low voltages as well thanks to the inversion mechanism. By running in a low power consumption state, DC Inverter ACs save a lot of electricity.

DC Inverter ACs isn’t as effective when running at full capacity, however, when they are running at partial capacity, which is how ACs are normally used, they can save a lot of energy.

The inverter AC has lower operating cost and with less breakdowns .The inverter AC units is more expensive in upfront cost than the constant speed air conditioners, but this is balanced by lower energy bills. The payback time is approximately two years depending on the usage.

 Due to the sophisticated operational method of the inverter, its compressor does not work at its full capacity all the time. When the speed is lower, the needed energy is lower too and you pay less money for electricity.

 The inverter AC is able to cool or heat your room faster than the non-inverter. This is due to the fact that in the beginning of the process, the inverter uses more power than the non-inverter and diminishes the power when it gets close to the desired temperature. The inverter air conditioner units may vary its capacity according to their needs; this makes the consumption to get adapted and lowers the electrical consumption significantly.

The stable speed units were very old in comparison to that, for they don’t have such electronics and they couldn’t modify its way of running and they worked in the same conditions though the weather was a 24ºC normal day or an extreme hot day with 38ºC, some stable speed units had pressure relief valves and condensing controls or different fan speed in the condenser, but this is nothing in comparison with all the things an inverter unit can do, regulating the gas flow with the electronic expansion valve, reducing or increasing the compressor speed, such as the condenser fan motor does. 

Cooling capacity of 1 ton is equal to 3.517 kW of power. For 1 ton AC inverter, power consumption of ac = cooling capacity/EER = 1.5*3.517/2.7=1.954 kW. AC consists of two units, Indoor unit which is called the evaporator and the Outdoor Unit which called the Compressor.

If you have a 1-DC Inverter AC, it will save you around 40-50 percent in electricity bills under normal usage. 3-DC and 4-DC Inverter ACs can achieve over 60 percent in savings. You probably won’t get 75 percent in savings under normal usage and extreme heat in Pakistan. However, if your AC has the heating-mode, it will cause more cost savings compared to the cooling mode.

Normal conditions mean that the user does not set temperatures to extremes. If the temperature is set to extremely low (for cooling) or extremely high (for heating) then you cannot expect such huge savings. However, even at extremes, DC Inverter ACs beat the conventional ACs.

Noise level and other benefits

The variable speed function makes the inverter AC unit’s quieter, extends life of their parts and the sharp fluctuations in the load are eliminated.  As the compressor motor of the inverter air conditioner does not turn on and off all the time, but keeps working at low power, the operation is more quite. The technology of the inverters not only makes cooling and heating more efficient, but it also makes the AC’s life longer As the compressor motor of the inverter air conditioner does not turn on and off all the time, but keeps working at low power, the operation is more quite.
The inverter air conditioner units get more comfort and faster than the stable speed ones.the inverter units reach to an assigned temperature faster than the stable speed units, apart from that, being capable of regulating their refrigerating capacity these maintain the room in a much more precise way than the stable speed ones because they go reducing their capacity slowly while reaching the desired temperature, maintaining that temperature “never stopping”. And that is put in inverted commas because I have heard that a lot. The inverter units never stop, my machine never stops”.

 Speed in cooling and warming.

The inverter units start slowly, it’s like a long-distance race, starting this way there’s neither a change in the intensity of current nor we feel a change in the intensity of bulbs, but they began to increase its capacity until they reach a 140% capacity in some cases.  In comparison to steady speed air conditioner units which either go or don’t go, the inverter air conditioner units have a wide range of operations, that’s the reason why catalogues used to show three different capacities: the nominal capacity, which is the “real” capacity or “basic” of that air conditioner and it’s the one we have to use to do the numbers more accurately (there are so many people who are wrong when taking as a reference the maximum capacity), the minimum capacity and the maximum capacity.

  The inverter air conditioner units  do stop  but only a few times In comparison to a stable capacity unit which switches itself on when the temperature goes a degree over our assigned temperature (cold mode) and it stops when it exceeds -1ºC, the inverter units work in a different way, these go reducing its capacity slowly when they reach their objective, and that’s the reason why seldom they exceed or reduce the temperature more than what it’s needed because it will keep itself a few degrees over or below our assigned temperature. It doesn’t mean it doesn’t stop, it does, but in general reducing its capacity and therefore its consumption is enough to keep the desired temperature.

Much more capacity

The inverter air conditioners are way much more efficient than those which aren’t inverter and they achieve an energy coefficient wider. Thanks to its electronics and the obvious progressions over these years, an actual inverter unit can reach a 5, 15 energy coefficient, that in comparison with a 2,76 of a non-inverter unit but same model, it is something to be aware of, it is almost the double of capacity and for that it means the half of consumption when doing the same work and air-conditioning the same room. Just for this reason choosing between an inverter and non-inverter one should be an easy choice to anybody.

Wider working range

Another inverter air conditioner characteristic which makes it better than a not inverter one is its working range, for example in heat mode. When the outside temperature reaches between 5 and 0ºC, a not inverter unit starts to fall its capacity heavily, even becoming ineffective and useless if the temperature descends even more, This is due to working in heat mode, the condenser will be cooling and it reaches to a point when it produces frost and it finally freezes itself, making impossible the heat or cold exchange with the outside. This is a solution with the called “defrost”, which almost every inverter unit has. With this defrost mode, what the unit does during a few minutes is to send the heat that should be going to the outside in order to warm our house, it sends it to the external unit to defrost it, loosing with this process the heat that should be impelling in the internal unit. After that, the unit will work normally until the next defrost, which will be more usual and shortened in time if there is more cold and humidity in the outside.

The inverter units don’t have such problems, or, if they have it is much less pronounced due to its electronics regulate the gas flow for this not to happen thanks to measurements, being able to work to -15ºC and loosing much less capacity than not inverter air conditioner units. There also exists special inverter units which works to -25ºC, giving a full capacity when they reach -15ºC

What Are the Different Types of DC Inverter ACs

Some manufacturers claim they have 3-DC Inverter ACs, All DC Inverter ACs, 4-D Inverter ACs, etc, while others simply claim to have Inverter ACs. They also claim to have varying savings percentages from 60 percent to 75 percent. The reason behind that is, some manufacturers employ older technologies and only upgrade their compressors to DC inverters. Others also convert the indoor and outdoor fan motors hence, completely upgrading all motors to DC inverters.

Those, which claim to save about 50 or 60 percent in electricity bills and simply state DC Inverter (or only Inverter) ACs, are using the inverter tech for the compressor only. 3-DC Inverter or 4-D Inverter systems, sometimes referred to as All DC Inverter, upgrade other motors or major electrical components as well. This means more savings as more electrical components get the ability to vary their speeds. In short, a number besides the “D” or “DC” mean the number of components using the inverter technology.

Conclusions

The inverter unit gives more comfort, capacity, saving, and other benefits and it has more working possibilities given the weather. On the contrary, the benefit of a not inverter unit will be that it costs less (upfront cost) and it also will cost less if it need to be repaired, because they are easier and cheaper to fix.  Not only do these ACs help save money, their use is good for the environment. The DC inverter technology is being used in other products as well