How does Power inverters work

  • Thread starter John1397
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How does a power inverter change DC into AC like do they use transistor or capacitors as I never seen the inside of one and wanted to know what components are used?

John
 

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  • #2
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John,

Power inverters are based on controlled semiconductors, that is semiconductors that turn on and turn off depending on the control pulses. These semiconductors are usually MOSFETs or IGBTs, both are transistors (the final "T" stands for transistor).

In a single-phase inverter you will find 2 transistors (search the web for push-pull inverter and half-bridge inverter) or 4 transistors (search for full-bridge inverter). In a three-phase inverter you will find 6 transistors (usually).

Inverters can be Voltage fed or current fed, and there are lots of control techniques, most of them chosen depending on the kind of load connected to inverter (a furnace or induction motor ...).
 
  • #3
Bobbywhy
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Also, in many high power inverters Silicon Controlled Rectifiers (SCRs) are used.
 
  • #4
davenn
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How does a power inverter change DC into AC like do they use transistor or capacitors as I never seen the inside of one and wanted to know what components are used?

John

but to get back to basics and answer your question :)

here is one very simple DC-AC inverter, couldnt get much simpler....

attachment.php?attachmentid=51158&stc=1&d=1348444188.gif


here is a slightly more complex one with more current handling....

attachment.php?attachmentid=51159&stc=1&d=1348444188.gif


3 basic parts to the inverter

An oscillator, Switching transistors, Transformer

The oscillator switches the DC voltage throuogh the transistors and the low voltage primary side of the transformer, producing either a square wave or sine wave. That induces a voltage into the hi voltage secondary windings of the coil.

Many inverters are a square wave type and for much equipment , thats OK, the down side is that square waves oscillations have many harmonics
but with some extra electronics you can produce a much cleaner sinewave in the transformer and thats better for equip that relies on a purer sinewave AC voltage

Dave
 

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