Shandong inverter allows you to get out of the misunderstanding of inverter energy saving


Release time:

2017-05-31

Shandong inverter allows you to get out of the misunderstanding of inverter energy saving

Shandong inverter allows you to get out of the misunderstanding of inverter energy saving
 

The variable frequency speed controller can save electricity because it can adjust the speed of the motor, and its energy-saving effect is only obvious when the load is specific. If the frequency converter is a power-saving control product, then all speed-regulating equipment can also be said to be a power-saving control product. In fact, the frequency conversion governor is only slightly higher in efficiency and power factor than other speed control equipment.11

Energy saving principle of frequency converter
 
In order to ensure the reliability of production, all kinds of production machinery have a certain margin when they are designed and equipped with power drives. The motor cannot run under full load. In addition to meeting the power drive requirements, the excess torque increases the consumption of active power and causes a waste of electrical energy. When the pressure is high, the operating speed of the motor can be reduced to make it work at a constant voltage. Save energy.
 
When the motor speed changes from N1 to N2, the relationship of the change of the motor shaft power (P) is as follows:
 
P2/P1=(N2/N1)^3, it can be seen that reducing the motor speed can get cubic energy saving effect.
 
Energy saving effect depends on load characteristics
 
Whether the variable frequency speed controller can save electricity is determined by the speed regulation characteristics of its load. It is incorrect to claim that the use of AC asynchronous motors and frequency converters saves electricity compared to the use of DC motors and DC speed regulators.
 
For loads such as centrifugal fans and centrifugal water pumps, the torque is proportional to the square of the speed, and the power is proportional to the cube of the speed. As long as the valve is used to control the flow, and it is not working at full load, it can save electricity if it is changed to speed control. When the speed drops to 80% of the original, the power is only 51.2% of the original. It can be seen that the application of the frequency converter in this type of load has the most obvious power saving effect.
 
For loads such as Roots blowers, the torque has nothing to do with the speed, that is, constant torque load. If the original method of using the air release valve to release the excess air volume is used to adjust the air volume, and it is changed to speed control operation, power saving can also be achieved. When the rotation speed drops to 80% of the original, the power is 80% of the original. The energy saving effect is much smaller than the application of centrifugal fans and centrifugal water pumps.
 
For a constant power load, the power has nothing to do with the speed. For constant power loads in cement plants, such as batching belt scales, under a certain set flow condition, when the material layer is thick, the belt speed slows down; when the material layer is thin, the belt speed increases. The application of frequency conversion governor in this kind of load cannot save electricity.
 
Compared with the DC speed control system, the DC motor has higher efficiency and higher power factor than the AC motor. The efficiency of the digital DC speed controller and the frequency conversion speed controller are comparable, and even the digital DC speed controller is slightly more efficient than the frequency conversion speed controller.
 
   Therefore, understanding the frequency converter as an energy-saving product has entered a misunderstanding. The most important function of the frequency converter is to realize the stepless speed regulation of the motor, and energy saving is only an accessory product in the stepless speed regulation process. The essence of its energy saving is that the drive system has a margin, and the frequency converter can save this part of the margin. When the drive system itself has no margin, the frequency converter cannot make a difference. On the contrary, the inverter will consume about 5% of its own rated power.

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