Inverter related knowledge

Many people know that frequency converter can save electricity, but they do not know why frequency converter can save electricity, and how much can be saved at the same time, is it high frequency or low frequency? In the following, we have sorted out some of the problems about frequency converters mentioned by customers.

1. If two identical motors are working at 50HZ power frequency, one uses frequency converter and the other does not, and the speed and torque are both in the rated state of the motor, can the frequency converter still save power? How much can you save?

A: In this case, the frequency converter can only change the power factor and does not save power.

2. If the torque of two identical motors does not reach the rated torque state of the motor (frequency, speed is still the same 50HZ), how much power can be saved by the one with the frequency converter?

Answer: If automatic energy saving operation is used, the frequency converter can step down operation at this time, which can save some power, but the power saving is not obvious.

3. Under the same conditions, how much can be saved under no-load state? Which of these three states can save more?

A: The drag load state does not save much power. For example, I think there's room for discussion about "closed-loop control," which is more than just speed sensor feedback. The frequency control of vector control is the closed-loop control, and it is the closed-loop control inside the device. The V/F control belongs to the open-loop control. In addition, there is the PID regulator feedback control of temperature, pressure, flow and other physical quantities, which is the category of closed-loop control. And all of them can be adjusted by frequency converter, so the concept of closed-loop control should not be explained so narrowly.

It is an indelible fact that frequency converters save electricity. In some cases, the power can be saved by more than 40%, but in some cases, it will be more wasteful than not connecting the frequency converter. The inverter realizes energy saving by reducing voltage with light load. Because the speed of the drag pitch load does not change much, even if the voltage is reduced, it will not be much, so the energy saving is very weak.

However, when it is used in the fan environment, it is different. When a smaller air volume is needed, the electric motor will reduce its speed. As we know, the energy consumption of the fan is proportional to the 1.7 times of the speed, so the rotation distance of the motor will drop sharply, and the energy saving effect is obvious. If we use it on the well, we're going to waste a lot of power by using the brake resistance on the return trip and we're going to waste more power.

Of course, if the environment requires speed regulation, the energy-saving effect of frequency converter is more obvious. Variable speed occasions will not save power, can only change the power factor. As an electronic circuit, the frequency converter itself also consumes power (about 3-5% of the rated power). A 1.5 piece of air conditioning its own power consumption is calculated down to 20-30W, equivalent to a permanent lamp.

It is a fact that the frequency converter runs under the power frequency and has the power saving function. But his premise is:

1. High power and fan/pump load;

2. The device itself has power saving function (software support);

3. Long-term continuous operation.

These are the three conditions to reflect the effect of power saving. Other than that, it doesn't matter whether it saves electricity or not, it doesn't make any sense. If the preconditions are not added to say that the frequency converter operation energy saving, it is exaggerated or commercial speculation. Once you know what's going on, you'll use him to your advantage. Must pay attention to use OCCASION AND USE CONDITION JUST GOOD CORRECT APPLICATION, otherwise it is blindly follow, credulous and "cheated".