Product Category

Wave Filter

Filters in Frequency Converters

A filter is a passive low-pass filter specifically designed to suppress the spectral components of electromagnetic interference generated by the frequency converter during operation. This is based on the electromagnetic compatibility characteristics of the interference to the power grid and other digital electronic equipment. It can effectively suppress conducted interference that propagates along the power line.

FST series input/output filters

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Types of Filters:

There are two types of filters used in frequency converters: input filters and output filters. There are certain differences between output filters and input filters:

(1)Difference in the Number of Turns in the Coil:

The input filter's coil typically has more turns than the output filter's coil.

This is because the higher harmonic components in the output current have a higher frequency, which is equal to the carrier frequency.

The harmonics at the input end are formed by the diode rectification circuit and the capacitor charging circuit.

The input current of the power supply to the frequency converter is actually the charging current of the capacitor, and the harmonic frequency here is slightly lower.

Therefore, to more effectively filter out these lower frequency harmonics, the number of turns in the coil of the input filter is slightly more than that of the output filter.

(2)Difference in Circuit Structure:

Most filter manufacturers connect capacitors at both ends of the filter coil to improve the filtering effect.

However, in the circuit structure of the output filter, there should be no capacitor on the side close to the frequency converter to avoid forming a possible resonance loop between the frequency converter and the power grid.

The capacitor connected on the motor side should be connected in series with a current-limiting resistor.

The purpose of this is to limit the surge current that may be generated during startup or operation, protecting the capacitor and the entire system.

Benefits of Using Filters:

Using these filters can significantly reduce the interference of the frequency converter to the power grid and improve the stability and reliability of the system. At the same time, they also help to meet the relevant electromagnetic compatibility standards and regulatory requirements.

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FST series input/output filters

Product Category

Wave Filter

FST series input/output filters

Types of Filters:

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