Converters and Inverters

Your question is vague, but if you are speaking in industrial electrical terms, they are used to describe systems of changing power from AC to DC or DC to AC.

A "converter" converts AC power into DC power, usually by the use of a diode bridge rectifier (Google that term for more specifics on that). So you supply AC electricity to the converter, it rectifies the AC into pulsating DC. In most cases, the "converter" will also include an inductor (choke) and /or capacitors in order to smooth out the "ripple" in the DC before the DC power is usable.

An "inverter" does the opposite, it changes DC into AC, or at least something that simulates AC power. There are several ways to do this, but the most common in use now is called PWM, which stands for Pulse Width Modulation (Google that term for more details). In short, PWM uses high speed switching of transistors to fire DC pulses of + or - voltage in a manner that emmulates an AC waveform when seen by the load. For this reason, you will see inverters used in UPS systems and small generators where the DC battery power must be used to supply AC loads. By varying the width of the pulses it can also vary the RMS voltage as well, making a PWM inverter capable of creating Voltage and Frequency at whatever specification is needed for the application. This is why you see PWM used in the inverter section of Variable Freqency Drives used with AC motors.

Hope that helped.

A "converter" converts DC power into DC power or AC into AC.

An "inverter" changes DC into AC or AC into DC.

Inverter is not a name for AC to DC conversion. It stands for only DC to AC convertion.

Krass,

What are you trying to explain? Would you please describe in more details?

If a device changes a type of current this one is INVERTER.

For example variable frequency drive (VFD) powered from DC line is INVERTER, but VFD powered from 3 phase AC line is MATRIX CONVERTER.

Some people are calling variable frequency drives (VFD's) "inverters".

Yes, but technically that has always been incorrect because a VFD contains both. That term was originally used to differentiate between an AC drive and a DC drive when the term Variable Speed Drive was more common, because VSD did not specify the type or power source. many people still use "inverter" when they mean VFD because they are stuck in the past. By using the term Variable Frequency Drive we no longer need to refer to the inverter being part of it because that is implied.

In addition, there are a lot of inverters available that are NOT variable frequency drives, especially with the explosion of solar power generation. In the marine industry, calling a VFD an inverter can get people confused because they have used DC input inverters for a long time.