operation of 3 phase inverter

Thread Starter

diya khan

Joined Nov 29, 2010
18
hey guys...


i want to know the operation of single phase and 3 phase inverter...please provide me links or books.. or jounals...anything is appreiciatedd

thank u soo much:)
 

strantor

Joined Oct 3, 2010
5,333
what kind of inverter? an inverter for powering electronic devices/appliances (like the kind you plug into a cigarette lighter and power your laptop) or a VFD (aka inverter) for controlling motors?
 

strantor

Joined Oct 3, 2010
5,333
The 3 phase inverter has a rectifier stage: incoming power, can be single phase for smaller VFDs, but usually 3 phase, is rectified into DC. The DC is filtered and stored in a capacitor bank.
From here it goes to the inverter bridge. The inverter bridge consists of 6 semiconductor switches, usually IGBTs, which are 3 sets of 2switches. the 3 points between the 3 sets of switches are the points where your motor connects. the way it works is, that one switch on the top closes and one switch on the bottom closes simulaneuosly (never 2 switches in the same set) and this will allow current to flow through one of the 3 windings.
When I say that these switches "close" - I do not mean that they close and stay closed. I mean that they pulse - it's called PWM - the duration of the pulse ON time determines how much current is allowed to flow through the winding. the frequency of this PWM is in the kiloherts range.
Now, there is a microcontroller inside which will determine how fast to cycle the commutation frequency (ex. 0-60hz) and the voltage (via PWM) based either from operator input (potentiometer or PLC) or internal PID algorithms.
 

Thread Starter

diya khan

Joined Nov 29, 2010
18
thank you!

is sumthing to do with harmonics? im sorry but my knowledge on this is very poor=/
my lecturer had asked me that why would the 3rd harmonic be reomoved? is it symthing to do with pwm?

my basics are soo poor!

=(
 
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