Frequency changer

A battery may also be added to the DC circuitry to improve the converter's ride-through of brief outages in the input power.

A variable-frequency drive (VFD) is a type of frequency changer used for speed control of AC motors such as used for pumps and fans.

This allows fan or pump output to be varied to match process conditions, which can provide energy savings.

Radio and combat systems equipment on Navy warships is often also powered by 400 Hz to reduce noise on the DC signal after rectification.

In renewable energy systems, frequency converters are an essential component of doubly fed induction generators (DFIGs) as used in modern multi-megawatt class wind turbines.

The Sakuma frequency converter station is one of the stations that links Japan's two grids (see Electricity sector in Japan § Transmission ).