Frequency Converters

Frequency converters are also known as frequency changers. These are devices that convert alternating current (AC) of one frequency to alternating current of another frequency. It is important to note that these electronic devices may also change the voltage, but if it does, that change is only incidental to its principal purpose. For that reason, do not use frequency converters if you need to adjust voltage.

In general, frequency converters of old were built out of electromechanical components. This might have included such things as motor-generator sets or rotary converters. But with the advent of solid state electronics, it has become possible to build completely electronic frequency changers. These modern frequency converters often consist of a rectifier stage (producing direct current) which is then inverted to produce alternating current of the desired frequency.

If voltage conversion is also needed a transformer will usually be included in either the AC input or output circuitry. In some cases, a battery may also be added to the DC (direct current) circuitry to improve the frequency converter "ride through" of brief outages in the input power.

Frequency converters will vary in power-handling capability from a few watts to megawatts. They will also vary in size and price, as you might imagine.

The most obvious application for frequency converters is for converting bulk amounts of power from one distribution standard to another, but frequency converters are also used to control the speed and the torque of some AC motors.

Another interesting application is in the fields of aerospace and airline industries. Often airplanes use 400 Hz power while in flight so a 50 Hz to 400 Hz frequency converter is needed for use while the plane is on the ground.

In addition, frequency converters are commonly used to control the speed of pumps and fans. In many applications significant energy savings are achieved through this technique. And as you might imagine, one of the most demanding application areas for frequency converters is in the industrial processing fields, where the control accuracy standards can be very demanding.

As an aside, the term frequency converter may also refer to a much lower powered circuit that converts radio frequency signals at one frequency to another frequency.

A careful reading of the product literature or project specs will reveal, without doubt, which type of frequency converters you are dealing with. Frequency converters should also be handled and used with care, and should never be left unattended where small children can play with them.