What is a Frequency Converter?
Regarding electrical power, Frequency is how many cycles per second an alternating current repeats. A Frequency Converter changes the number of Cycles per Second (Hertz). In the figure below the frequency coming out is 6 times the frequency going in. This has nothing to do with Voltage or Amperage. Only the frequency is changed. Conversely a higher frequency could be converted to a lower frequency.
How does a Frequency converter work?
Originally, Frequency Converters were mechanical. An engine or motor would be connected to a pulley or gear transmission to drive a generator faster or slower than the motor. Since Frequency is proportional to the generator speed, it would be increased or decreased by the pulley or gear ratio. This had limitations on speed, available ratios, and stability. If the motor or power line fluctuated, the generator output frequency fluctuated. Efficiency of power passing through the motor plus a generator was often low.
Today the Frequency Conversion is done electronically. Any type of power source can be changed to Direct Current (DC). Direct Current has no frequency, behaving like a battery. This DC can then be pulsed in tiny slices to create any frequency desired.
This Solid State Frequency Converter design is highly efficient, stabilized by a quartz crystal, and operates independent of input power fluctuations.
It requires minimal maintenance, no lubrication, or mechanical wear.
Uses for Solid State Frequency Converters
Variable Frequency Converters
Because the speed of a motor is proportional to Frequency, varying the frequency will vary the speed. This is valuable in many applications such as printing and conveyor systems. In air handling systems the economics are important. Reducing the fan speed by 2 reduces the fan pressure output by 4. (Square Law) At the same time the power used is reduced by 9. (Cube Law) The reduction of speed rather than closing a damper to reduce flow generates substantial energy savings.
Fixed Frequency Converters
Although variable speed has many uses, the need for a fixed frequency different from the utility is often a requirement. Many countries power grid operates on 60 Hertz while other countries operate on 50 Hz. Because of the global economy, manufactures producing for foreign markets must test their product at the frequency of the foreign country power. A Frequency Converter allows a factory in a 60 Hz country to test products on a 50 Hz power source, or the other way around. Renewable energy systems such as solar or wind need frequency converters to convert their power to utility grid frequency so that the power can be used by consumers. Frequency is a large factor in the design of power equipment. One relationship is that higher frequency requires less iron in motors and transformers. This means that operation above the 60 or 50 Hz utility power can save size and weight in equipment. This is particularly important for equipment that is flown or transported frequently. Aircraft and Military systems take advantage of this by being designed to operate on 400 Hz. This higher frequency, because equipment weighs less, allows more capacity for fuel and cargo. Utility grid power converted to 400 Hz is a critical part of Commercial and Military aviation globally. Other Military equipment such as missile systems and computers also utilize 400 Hz. Although various countries standardize on different grid frequencies, the aviation frequency requirement is the same everywhere.