Principle of Inverter of Frequency converter(2)

Equipped with source power filter.

Besides the traditional LC filter is still in use, active power filter is used to suppress  harmonic as an important trend .When connected to the main circuit in series or parallel, the harmonic current is detected from the compensation object simultaneously, and the compensation device generates a compensation current which is equal to the harmonic current and the direction is reversed, so that the power grid current contains only the fundamental component. This filter can track and compensate harmonics with varying frequencies and amplitudes, and its characteristics are not affected by the system and there is no danger of harmonic amplification, so it has attracted much attention and has been widely used in Japan and other countries.