Homeowners, business leaders and other choice of air conditioning, the core considerations can not be separated from the “comfort, energy saving, cost”, but fixed-speed, frequency conversion, digital scroll three types of mainstream products make it difficult to choose.
In this article, we will work from the principle, advantages and disadvantages, applicable scenarios to dismantle the core differences between the three types of air conditioning, to help you accurately match the needs of the selection of the right not to step on the pit.
What Is a Fixed Speed Air Conditioner?
Fixed-speed air conditioning (also known as non-inverter air conditioning) to a single-speed compressor as the core, using the “start-stop” operation logic: room temperature reaches the set value after the compressor is automatically shut down, to be the temperature beyond the threshold and then restarted, the operating state of only two kinds of: full-load work or complete shutdown.
Although inverter air conditioning has been widely popularized, fixed-speed air conditioning in some countries and regions of the market heat has fallen, but with mature technology and stable performance, it is still a reliable temperature control program in many scenarios.
What Is an Inverter Air Conditioner?
The core of an inverter air conditioner is a variable-speed compressor, which is different from the “start-stop mode” of a fixed-speed air conditioner, and can adjust its speed in real time according to the fluctuation of the indoor temperature. When the set temperature is reached, the compressor does not need to stop, but only switches to low power continuous operation, which can stabilize the room temperature and enhance the sense of physical comfort.
Inverter air conditioners are mainly divided into two categories: AC inverter and DC inverter, with the core differences centered on the compressor and control system:
- AC inverter: AC motor drive, with the help of PWM (pulse width modulation) technology to achieve frequency conversion, control circuit design is relatively simple. Compared with fixed-speed air conditioning, it is faster cooling and heating, more accurate temperature control, but there is power loss in the rotor winding, the cost is more affordable.
- DC inverter: equipped with brushless DC or permanent magnet synchronous motor, borrowing the stator and rotor permanent magnetic field direct drive, rotor winding, no additional power supply, power loss is very low; efficiency than the AC inverter 10% to 30% higher, the noise is reduced by 5 to 10 decibels, is an advanced inverter program.
Difference between DC Inverter AC and Traditional Fixed-frequency AC
Inverter air conditioner is based on the principle of inverter, through the secondary inverter to obtain a variable AC power supply, which regulates the speed of the compressor, and then changes the amount of refrigerant circulating in the pipeline, and ultimately accurately control the air conditioning output capacity.
The applicable working voltage range is large; the starting current is small; the high power operation quickly reaches the set temperature, and the low power maintains and balances the room temperature, thus the cooling and heating are rapid, energy-saving, and the room temperature fluctuation is small.
The core feature of fixed-speed air conditioning is equipped with a single-speed compressor, constant speed and can not be actively adjusted with the room temperature power, mainly by the compressor start-stop cycle of temperature control: room temperature up to a preset threshold shutdown, over the threshold is restarted to run at full capacity to maintain the basic control of the temperature in an “intermittent” mode.
When running, fixed-speed air conditioners always run at full load with a fixed power to maintain the set temperature through frequent starts and stops, which leads to slower cooling and heating, not only a greater impact on the home power grid, but also cause significant fluctuations in room temperature.
AC Inverter vs DC Inverter Air Conditioner
Compressor
AC inverter and DC inverter air conditioner compressor motor, the core principle is the same – are generated by the stator rotating magnetic field, with the help of electromagnetic force between the stator and the rotor to drive the rotor to rotate, but the two in the structural design and performance performance there are significant differences:
AC inverter
using the AC motor AC inverter adopts AC motor to drive, relying on the interaction between the magnetic field of the stator and the rotor to drive the rotor. Its special structural design supports the adjustment of motor speed through a wide range of adjustment of power frequency and voltage, compared with fixed-speed air conditioning, cooling and heating faster, more accurate temperature control. However, there is a current through the rotor winding, which generates power loss, but the cost is much lower than DC inverter air conditioners.
DC inverter
is driven by a DC motor and operates through the direct interaction of the stator’s rotating magnetic field and the rotor’s permanent magnetic field. Since the rotor is a permanent magnet, there is no coil/winding design, no external power supply is required, no power loss, and it has the core advantage of high efficiency and energy saving.
Its efficiency than the AC inverter compressor to improve 10% to 30%, noise reduction of 5 to 10 decibels, and AC inverter air conditioners belong to two generations of technology products.
Control System
AC Inverter
adopts asynchronous control mode: 220V/50Hz utility power is converted to about 310V DC after rectification and filtering, and then the inverter generates the inverter power supply to drive the compressor.
The core adopts the PWM technology, which realizes the inverter voltage conversion by splitting the pulse wave and adjusting the duty cycle of the pulses, and the whole adjustment process is completed in the inverter, with a concise structure of the control circuit.
DC Inverter
adopts synchronous control mode, which detects the compressor rotor position in real time and dynamically adjusts the operating frequency; in terms of motor type, the use of brushless DC motor (120°) or permanent magnet synchronous motor (180°) corresponds to DC inverter.
If AC motor is used, it is AC inverter. Among them, full DC inverter refers to the compressor and indoor and outdoor fans are equipped with brushless DC motors, and part of the DC inverter only compressor with brushless DC motors.
What is Digital Scroll Air Conditioner
Digital Scroll air conditioner is a technological upgrade of the traditional scroll air conditioner iteration of the product, as a type of air conditioner focusing on precise capacity adjustment.
Its core technology relies on PWM (pulse width modulation) unloading mechanism, through the computer intelligent control system on the compressor capacity of real-time, precise regulation, so as to achieve on-demand output of cold/heat efficient regulation, taking into account the stability of operation and energy efficiency. Performance.
Working Principle of Digital Scroll Air Conditioner
- Core control mechanism: through the solenoid valve drive, precise control of the internal vertical displacement of the two intermeshing scroll disk, to realize the compressor “loading” and “unloading” two smooth switching of the working state.
- Two operating states: under the loading state, the compressor is running at full load, completing the normal compression cycle of the refrigerant; under the unloading state, the scroll disk is separated without compression, and the compressor only maintains idle standby.
- Key operating parameters: loading-unloading cycle of about 20 seconds, capacity adjustment range covering 10% ~ 90%; through precise adjustment of the loading time as a percentage of the stepless capacity output, and the compressor continues to run throughout the whole process to ensure stable temperature control.
Comparison between Digital Scroll and Inverter Scroll Compressors
Capacity Adjustment Speed
- Digital Scroll technology: the capacity output range covers 10%~100%; the compressor output can be changed by adjusting the loading time ratio, realizing stepless continuous capacity supply and extremely rapid response to load changes.
- Inverter technology: the operating frequency range is 52~210 Hz, the compressor can only operate at limited capacity levels (e.g. 21 levels), and the capacity output is intermittent. When the indoor load suddenly increases, the compressor frequency increase needs to go through an intermediate transition phase, there is a delay in response to load changes, and cannot instantly adapt to the demand.
Energy efficiency ratio COP
- Digital Scroll technology: no additional loss brought by the inverter system, no need to adjust the capacity with the help of refrigerant hot gas bypass, excellent COP performance in the 10%~100% full-load range; energy consumption of only 10% under no-load condition, even under part-load working conditions, COP value is still outstanding.
- Inverter technology: about 15% system power loss pulls down the COP; low load (10%-30%), due to the compressor minimum output of 40% hot gas bypass regulation, additional loss aggravates the decline in COP; dynamic changes in the motor frequency makes it difficult to accurately determine the COP, fixed-frequency test does not include inverter loss, not counting the 15% system loss is easy to be overstated.
Electromagnetic Interference
- Digital scroll technology: the core of capacity adjustment is load/unload switching, no need for complex frequency conversion, reducing electromagnetic interference from the root, basically no interference with electromagnetic radiation, fully compliant with EMC electromagnetic compatibility standards, suitable for electromagnetic strict requirements of the scene.
- Frequency conversion technology: the need to continuously adjust the frequency through the frequency converter, easy to generate high harmonics, electromagnetic interference, does not meet EMC standards; communications room, precision laboratory and other sensitive places of equipment vulnerable to interference failure, so it is not applicable.
Which Air Conditioner should You choose?
Fixed Speed Air Conditioner
is suitable for scenarios with limited budgets, low frequency of use (such as guest rooms and seasonal storage rooms), and low requirements for room temperature fluctuations and energy saving, making it a cost-effective choice for such needs.
Its simple structure, affordable price, and hassle-free maintenance are especially suitable for the basic temperature-control needs of small areas, such as singles’ apartments.
Inverter Air Conditioner
are the first choice for homes that are used for more than 8 hours a day, with DC inverter models combining the core advantages of comfort and energy efficiency; they are characterized by precise temperature control, rapid cooling and heating, low starting current, and adaptability to environments with fluctuating voltages; their low-noise design is suitable for scenarios involving the elderly and children, and they are also more energy-efficient in the long term.
Digital Scroll Air Conditioner
is suitable for commercial/special scenarios, such as shopping malls/conference rooms with large personnel flows and frequent load fluctuations (10%~100% capacity adjustment for precise adaptation), and data centers/medical laboratories that are electromagnetism-sensitive and require 24-hour stable operation, with significant advantages in terms of low interference and high stability; and for 24-hour operation of office buildings and factories, with long-term cost savings due to high energy efficiency under partial load.
Conclusion
Before choosing, make clear the duration of use, budget and purpose; prioritize DC inverter or digital scroll models for high-frequency use or precision scenarios, and reasonable investment in the early stage can be exchanged for a long-lasting comfortable experience and energy-saving and cost-saving benefits.
Match the needs or consult with professionals to accurately select products and match the needs.
