Why is the ex factory value of the carrier frequency of the inverter different for the noise of diff

This carrier frequency is not recommended to be set casually. The factory value is 4kHz, you adjust it to 8kHz, the motor noise decreases, which means that the output waveform is good. You can imagine that a wave was originally cut into 4k segments, and now it is chopped into 8k segments, then, the waveform must have changed for the better.

However, the life of the inverter, heat generation, etc., will be affected.

Generally speaking, the higher the power of the inverter, the lower the carrier frequency.

If there is noise, it is best to install a frequency converter output filter at the output end of the frequency converter, or an output reactor of the frequency converter to filter and improve the output waveform of the frequency converter.

The carrier frequency is high, the noise is small, because the harmonic composition is low, the principle of the inverter is determined.

Theoretically, if the carrier frequency is above 20kHz, people will not be able to hear the noise.

However, the higher the carrier frequency, the greater the switching losses of the corresponding switch. At present, there is no company that can achieve a carrier frequency of more than 20kHz. In addition, the higher the current, the greater the switching losses. Therefore, the carrier frequency should be appropriately lowered for high-power electricity.

Of course, if your application is sensitive to noise and the efficiency is in an acceptable range, you can also adjust the carrier frequency appropriately.

The increase in the carrier frequency of the inverter will reduce the electromagnetic noise, but the rated output current will need to decrease by 5% for every increase in the carrier frequency of 1kHz due to the increase in the loss of the inverter, which will cause heat generation

There is a formula for your problem to refer to and analyze: Motor power: p= motor torque:

t=9549×p/n ；Motor speed: n=60f p, p is the number of pole pairs of the motor, for example, p=2 of the four-stage motorNote: When the frequency reaches 50Hz, the motor reaches the rated power, and then increases the frequency, the power will not increase again, and the rated power will be maintained.

For asynchronous motors: t=k i x (k: constant, i:

current, x:magnetic flux); It is easy to see the change of frequency f, also accompanied by the change of e, the voltage of the stator should also change, in fact, the commonly used frequency converter speed regulation method is like this, when the frequency changes, the output voltage of the frequency converter, that is, the voltage added to both ends of the stator is also changed, is proportional, this is the constant V f ratio frequency conversion mode. These three equations can also be used in the previous analysis to give the same result.

When the motor torque is below 50Hz, it changes proportionally to the frequency; When the frequency f reaches 50Hz, the motor reaches the maximum output power, that is, the rated power; If the frequency f continues to increase after 50Hz, the output torque changes inversely proportional to the frequency, because its output power is so large, and you have to continue to increase the frequency f, then the torque will be significantly reduced by applying the above calculation analysis. The situation and frequency of the speed are the same, because the power supply voltage is unchanged, and the direct result of the change of its frequency is the year-on-year change of the speed.

Is it the relationship between the operating frequency and power consumption of the inverter motor? The motor power consumption of the fan pump load is proportional to the cube of the speed, and the speed of the motor operation is proportional to the frequency of the motor, therefore, for the fan pump load, the power consumed by the motor is proportional to the cube of its operating frequency. In the case of constant power loads, the power consumption is not related to the frequency of operation.

If the general frequency conversion control is above the fundamental frequency, the constant voltage frequency ratio control is used, that is, the voltage is proportional to the ratio of frequency, and the voltage is related to the power.

The rated frequency of the inverter motor is its base frequency.

When the operating frequency is lower than the base frequency, the motor can regulate the speed with constant torque, and the power is proportional to the frequency. When the operating frequency is higher than the base frequency, the motor runs at constant power, and the power is independent of the frequency.

To put it simply, frequency is rotational speed. When the speed is high, the power of the natural motor is also high, and the heat generation is large.

Frequency and power are directly proportional.

Summary. The load is not the same.

The load is not the same.

Drag the same locomotive.

Drag the same locomotive.

One before and one after the other. One before and one after the other.

Yes. The load of the motor affects the current.

Even if the frequency is the same, the current is different.

75kw two motors, one before and one behind, the frequency is the same, the current difference is 2oa75kw two motors, one before and one behind, the frequency is the same, the current difference is 2oa normal. Two electric motors.

The frequency is the same. Right.

Right. But the load is not the same.

The current generated is not the same.

The two inverters control two motors with the same power one in front of the other and one behind respectively, and drag the two wheels through the reducer.

The two inverters control two motors with the same power one in front of the other and one behind respectively, and drag the two wheels through the reducer.

Is it harmful to the device?

Is it harmful to the device?

Oh, no. This is normal.

Summary. Why should the output basic frequency of the inverter be consistent with the rated frequency of the motor? Hello!

There are two reasons for pro: 1If the fundamental frequency is set lower than the rated frequency of the motor, the motor voltage will increase, and the increase of the output voltage will cause the increase of the magnetic flux of the motor, saturating the magnetic flux, distorting the excitation current, and causing a large spike current, which will cause the inverter to trip due to overcurrent.

2.If the fundamental frequency is set higher than the rated frequency of the motor, the motor voltage will decrease and the load carrying capacity of the motor will decrease.

Why should the output basic frequency of the inverter be consistent with the rated frequency of the electric Hongyun Tong motor? Hello! There are two reasons for this:

1.If the basic frequency is set to be lower than the rated frequency of the motor, the motor voltage will increase, and the increase of the output voltage will cause the increase of the magnetic flux of the motor, so that the magnetic flux of the shield will be saturated, the excitation current will be distorted, and a large peak current will occur, which will cause the inverter to trip due to overcurrent. 2.

If the fundamental frequency is set higher than the rated frequency of the motor, the motor voltage will decrease and the load carrying capacity of the motor will decrease.

The frequency corresponding to the maximum output voltage of the inverter is called the basic frequency, and the output frequency when the output voltage of the frequency conversion is equal to the rated voltage is called the main frequency. In most cases, the main frequency is equal to the rated frequency of the motor, and the inverter changes the voltage of the output power supply at the same time as changing the frequency of the output power supply, which is called frequency conversion and voltage conversion. The basic frequency is the minimum output frequency when the output voltage of the inverter is equal to the rated branch overvoltage.

The highest frequency is the maximum frequency that the inverter is allowed to output, which is expressed by fmax. The specific meaning varies slightly depending on how the frequency is given.

The carrier frequency is low, and the harmonics generated by the inverter are many, however, the waveform is not smooth; The carrier frequency is high, and the harmonics generated by the inverter are smaller, but the smoothness of the waveform is greatly increased.

The carrier frequency is appropriate, which can extend the service life of the inverter, because the life of high-speed switching devices such as IGBT is also related to the number of switching times. The higher the carrier frequency, the shorter the service life of the inverter, therefore, the manufacturer does not recommend a larger increase in the service life of the inverter.

If the carrier frequency is low, the waveform output by the inverter is not smooth enough, that is, the harmonic content is relatively rich, then, after these harmonics enter the motor, it may cause overheating, vibration, acoustic noise, rapid aging of insulation, bearing damage and other conditions of the motor.

Finally, let me explain: this is still a controversial topic at present, personal opinion, don't spray if you don't like it!!

The carrier frequency of the inverter is the frequency that determines the number of times the inverter's power switching device (e.g., IGBT) is turned on and off.

It mainly affects the following aspects:

1. The power loss of the power module IGBT is related to the carrier frequency, the carrier frequency increases, the power loss increases, and the heat generation of the power module increases, which is not good for the inverter.

2. The influence of carrier frequency on the waveform of the output secondary current of the inverter:

When the carrier frequency is high, the current waveform is sinusoidal and smooth. When the carrier frequency is too low, the effective torque of the motor is reduced, the loss is increased, and the temperature is increased, on the contrary, when the carrier frequency is too high, the loss of the inverter itself increases, the IGBT temperature rises, and the rate of change of the output voltage dv dt increases, which has a greater impact on the insulation of the motor.

3. The influence of carrier frequency on the noise of the motor: the higher the carrier frequency, the smaller the noise of the motor.

4. Carrier frequency and the heating of the motor: The heating of the motor with high carrier frequency is relatively small.

In actual use, the above points should be combined and the carrier frequency of the inverter should be reasonably selected. Generally, the greater the power of the motor, the smaller the load rate is selected.

The carrier frequency has an effect on the output current of the inverter.

1) The higher the operating frequency, the larger the duty cycle of the voltage wave, and the smaller the composition of the higher harmonic of the current, that is, the higher the carrier frequency, the better the smoothness of the current waveform;

2) The higher the carrier frequency, the smaller the allowable output current of the inverter;

3) The higher the carrier frequency, the smaller the capacitive reactance of the wiring capacitor (because xc = 1 2 fc) and the greater the leakage current caused by high-frequency pulses.

Effect of carrier frequency on motor.

The higher the carrier frequency, the smaller the vibration of the motor, the less noisy the operation, and the less heat generated by the motor. However, the higher the carrier frequency, the higher the frequency of the harmonic current, the more serious the skin effect of the motor stator, the greater the motor loss, and the smaller the output power.

The higher the carrier frequency, the greater the loss of the inverter and the smaller the output power. If the ambient temperature is high, the dead zone of the upper and lower inverter tubes of the inverter bridge will become smaller during the alternating conduction process, which can lead to a short circuit of the bridge arm and damage the inverter in serious cases. The carrier frequency is high, the current output waveform is ideal, the torque is large at low frequency, and the motor noise is small.

It is suitable for places where low-frequency output, high torque and silence are required. However, at this time, the switching loss of the main components is large, the whole machine generates more, the efficiency decreases, and the output decreases. At the same time, the radio interference is large, and another problem in the use of high carrier frequency is the increase of capacitive leakage current, which may cause its malfunction when equipped with leakage protector, and may also cause the occurrence of overcurrent, resulting in overheating protection of the inverter.