How BLDC Motors Revolutionize Air Compressors with Energy Efficiency
An ultra-low temperature freezer is a device capable of providing extremely low temperature environments. It is widely used in various fields such as biomedicine, research, and industry. Its core function is to maintain sample temperatures at -80°C or even lower through advanced refrigeration technology, thereby achieving long-term storage of biological samples, reagents, and special materials.
Working principle of ultra-low temperature freezer
A standard short-term storage freezer using a single-stage compression refrigeration cycle can typically only reach a temperature of -20°C. Ultra-low temperature (ULT) freezers, on the other hand, employ multi-stage compressors and cascade refrigeration cycles. Most ULT freezers use two-stage compressors and can achieve temperatures as low as -86°C.
Ultra-low temperature freezers typically employ a two-stage compression system. In the first stage, the refrigerant is compressed to a higher pressure and then enters the condenser to release heat and liquefy. The liquid refrigerant passes through an expansion device into the low-temperature evaporator, where it evaporates and absorbs heat, lowering the surrounding temperature. The second-stage compressor then compresses the low-pressure gas generated by the low-temperature evaporator, increasing its pressure and temperature, before entering the high-temperature condenser to release heat. This cycle continues.
Refrigeration compressors are often powered by simple and inexpensive induction motors to perform the compression work. However, a significant issue is the relatively low efficiency of induction motors (typically below 70%), which causes them to generate heat. All heat generated by induction motors in the refrigeration system must be removed from the system through the refrigeration cycle. This means that part of the refrigeration system's work is simply to remove the system's own heat generation, rather than removing heat from the freezer.
BLDC motors offer a viable solution
Brushless DC (BLDC) motors differ from induction motors in several key principles. Notably, BLDC motors are driven by direct current voltage, while induction motors are powered by alternating current. Induction motors have windings to generate magnetic fields, whereas BLDC motors utilize permanent magnets. Induction motors are relatively easy to control (simply by applying power), while BLDC motors require more sophisticated electronic controls. Due to these differences, BLDC motor solutions tend to have higher implementation costs compared to induction motor solutions.
Due to high costs and complex implementation technology, BLDC motors have not been widely adopted in compressors for ultra-low temperature freezers. However, some compressors for new air conditioners have verified the feasibility of this concept. Using BLDC motor-based compressors in ultra-low temperature freezers will bring benefits commensurate with the additional costs. Moreover, with recent technological advancements, the cost and complexity of controlling BLDC motor solutions have been significantly reduced.
Advantages of BLDC Motors
Compared to asynchronous induction motor pump systems, this compressor system uses permanent magnet motors. Due to the following advantages, it is suitable for applications with different requirements, can save up to 35% of energy, and extend the life of the compressor.
Soft Start and Longevity
Excessive current drawn during the star-delta of the electrical motor (starting current) and the mechanic loads are eliminated thanks to the soft start and stop features of this system. As a result, longevity of the motor equipment improves and maintenance costs decrease.
Economical Run and Constant Output Pressure
Standard air compressors switch to idle when the targeted pressure is achieved and switch to load when the specific low pressure is reached. When the compressor switches to idle, the electrical motor keeps working at its constant speed and does not produce compressed air hence the compressor consumes 30% power of its load run. Pumps with our permanent magnet motor, works at an optimum speed (rpm) to meet the real time air needs and provides great deal of energy savings as well as producing targeted constant output pressure.
In some cases, because we can’t rule out the possibility of long run in full load condition, we have to order motors to meet maximum demands of compressors. But in actual operation, the proportion of light load running time is quite high, it leads to a lot of energy waste. From now on, with our permanent magnet motor system, you can order a motor at rated power, and peak power can meet the full load condition. By the close loop control, the motor speed is variable automatically by your pressure condition.
In addition to the air compressor motor, in some cases, the fan cooling is required in the compressor. Volcano Electric offers one-stop solution including the intelligent cooling systems.