How to select a filter for the drive

- Jul 24, 2019-

The inverter filter is specifically designed for the characteristics and laws of harmonics produced by the inverter, and a specially developed type filter is a kind of LC filter. Overview The inverter filter is mainly a passive device consisting of inductors, capacitors, resistors, etc. It is a kind of low-pass filter that allows the frequency-frequency signal converter input filter number to pass without blocking and suppressing high-frequency electromagnetic interference (generally speaking, the interference noise frequency is 50/60 to 1kHz).

The inverter filter is a two-way reversible device, that is, to prevent electromagnetic noise on the power grid from entering the equipment through the power supply, but also to prevent the electromagnetic noise of the equipment itself to pollute the power grid. The inverter filter is an effective tool for suppressing conduction interference.

The special filter of the inverter can be divided into two kinds of inverter input filter and output filter according to the different installation position.   

These two filters are not only different installation locations, their functions are not the same, and the installation location sits not interchangeable. Therefore, in the application of the special filter of the inverter, the first problem to be solved is the selection of the special filter of the inverter. In the selection process, we must be clear about the following two points:

The first is whether the inverter input filter or the inverter output filter should be chosen.   

1. observation method. This is also the simplest way to judge, is to remove the output line of the inverter, and then, to power up the drive, so that it can reach a normal working state, at this time, we will observe, interference is still there, if there is, in general, is the need to add the inverter input filter. Conversely, the inverter output filter needs to be added, or it may be that the inverter input filter and the drive output filter need to be added at the same time. Please note that what we say here is the general situation, not 100% accurate.

2. oscilloscope method. If you have an oscilloscope on hand, you can use the oscilloscope to measure the inverter output and output, as well as the waveform of the input of the interfered device, through the waveform to see where the interference source, and then decide whether to choose the inverter input filter, or the inverter output filter.

Second, it is to clarify the voltage rating of the inverter Here, we need to know whether the drive is a single-phase power supply, or a three-phase power supply.

Third, it is necessary to make it clear that the rated current of the inverter the special filter of the inverter must pay attention to this point when selecting, otherwise, it may be counterproductive.

Precautions

Avoid coupling of inputs and outputs

Strong power weak power to be separated