UPS system

I suspect you are talking about double conversion on-line and line interactive UPS systems


APC have some great white papers, such as this one  https://download.schneider-electric.com/files?p_File_Name=JSII-5YQSBR_R1_EN.pdf&p_Doc_Ref=SPD_JSII-5YQSBR_EN&p_enDocType=White Paper


basically, the cheap ones run the load off mains power direct, and change over when the power fails, the expensive ones run the load on the UPS all the time with the AC-DC DC-AC setup

A rectifier always takes an AC and makes a DC - usually with various arrangements of diodes.

An inverter takes a DC and chops it to make an AC, albeit a sine wave of varying lumpiness made by sticking together rectangles

A converter could be either of the above or even both.

beware the English

hello, 

let start with d simple definition ,rectifier is a device which convert alternating current to direct current 

A rectifier convert from one form to another. it can can be either AC to DC or DC to DC and the opposite if this is inversion where the DC is inverted to AC. (inverter)

If you can, get hold of a copy of Kohlers 'The UPS handbook' - it's a great book & covers a lot of the fundamentals

thanks guys all good descriptions and appreciate the link .

A rectifier is generally a simple passive device made up of one or more diodes. A diode is basically a non return valve for electricity so only allows current to flow in one direction, that means if you put AC in, you get wavey DC out at approx the SAME voltage as the AC


A converter is generally a fairly complicated circuit (that may contain one or more rectifiers as well as lots of other stuff) that, depending on the type can convert AC to DC, DC to DC, AC to AC or DC to AC and either increase or decrease the voltage or frequency.