Frequency converter Vs Frequency inverter
Often, the manufacturers and marketers of these devices are faced with the dilemma of deciding what is the best combination of words, in the local language, to name them in a simple, short and unequivocal way. Let’s see the differences :
Frequency converter : It is a correct term but it could also be interpreted as a frequency conversion equipment dedicated to an adaptation of the power source.
Variable frequency drive : It is the most common term in our country to refer to a VFD. Although you can also define other types of devices used in aeronautics or laboratories (variable frequency generators).
Inverter Vs Converter
Ultimately, inverters have only one job: taking direct current (DC) and converting it to alternating current (AC). Theoretically, this is a breeze, as a simple switch and creative wiring can provide you with an alternating square wave that operates at the frequency selected on the switch.
So the real question is: how is it possible to take AC power and make it usable? The answer is that you can filter the square wave by precisely selected capacitors and inductors in order to create a sine wave, or at least somewhat similar to a sine wave.
Often inverters will also include a transformer . This is done so that the AC voltage output can be really different from the DC voltage input, depending on the number of coils in the primary and secondary winding.
There are two common types of inverters :
Pure Sine Wave Inverter (PSW): The output from a pure sine wave inverter is as you can guess a pure sine wave. Achieving a perfect sine wave as an output is very difficult, and the designs for doing so can be very complex.
Modified Sine Wave Inverter (MSW): These can use thyristors, diodes, and other passive elements that produce a rounded square wave and actually come very close to the output of a pure sine wave. Often MSWs can be used for high power electromechanical equipment.
Converters also have only one job: converting AC power to DC power. For example, if someone says “DC to AC converter” it makes sense, even if the correct terminology is “DC to AC inverter”. The same argument can be made if we say “DC to DC converters”. Also, AC to DC converters are generally referred to as power supplies.
There are two common types of converters :
Half Wave Rectifier : Generally these are only used in low power applications because their signal is not very uniform in nature. Since half of the AC signal is lost, the output amplitude is almost 45% of the input amplitude, which means that that energy is largely wasted during the negative half cycle of the input. Even when a large capacitor is placed over the load, there is still excessive ripple during the AC input drop cycle.
Full Wave Rectifier : Design engineers use a full wave rectifier to avoid this signal loss and get a much cleaner signal. These rectifiers capture the positive and negative cycles of the AC source and are used for applications that require a stable and uniform DC voltage source.
Generally, you will find that full -wave rectifier circuits are designed in two ways: In the first, a multi-winding transformer is used that creates a purely positive signal that can then be smoothed out by a capacitor on the load. The second is known as a full- wave bridge rectifier and, in fact, does the same thing as the transformer full-wave rectifier, but in this case, it is a smaller configuration because there is no transformer. Essentially, either option consists of the same strategy as the half-wave rectifier, except that there is twice the AC input frequency and the input almost never reaches zero.
So you can see how rectifiers and transformers are part of the broader spectrum of converters vs inverters. We hope this post helps you choose the right part.