Inverter max power can handle

Using SPWM and components below, can someone tell me the max power my 3phase inverter can handle? The mosfets i want use says max 8A current, but i think means Iavg. And i trying find the max HP motor my inverter will handle..

That's the rectifier i used:

and that's the P.Mosfet:

On inverter input comes an 230V 50Hz 1phase line.


I don't see what inverter you are using. Check the data sheet. They often say a max voltage and current capacity.

I mean if i try to build my own with these components.

A schematic would be helpful. Usually the capability is the capability of the least powerful part, in this case the transistors.

Is this schematic similar to what you are thinking?

This web site has an hp calculator.

What kind of motor are you expecting to power? A schematic of what you are intending to build would help. 3 phase motors normally run off 415 V .

Yes thats the schematic.

DC is created from single phase line 230V 50Hz.

Yeah i think too my mosfets are the base for calculate power.

I use IRF840 with IS2109 drivers.

Mosfet datasheet say 8A max current.But i dont think its RMS value

  1. You are using MOSFETs, not IGBTs - that’s really going to be an issue at those voltages
    as MOSFETs are more fragile. If you haven’t built power bridges before expect to
    blow things up a lot.
  2. The IRF840 is an n-MOSFET, not a p-MOSFET - did you mean “power MOSFET”?
  3. You are using old devices with a whopping great 800 milliohm on resistance,
    look for something better, 100milliohms is findable at that voltage rating.
  4. Losses may be dominated by switching time, you haven’t said anything about
    your driver circuits.

If you want an easier life go for an IGBT IPM…

I am using 6 N-channel power mosfets IRF840.

Driving the with IR2109 device.They have 1 input and create 2 signals with
dead time.

Its going to contol low motor max 1.5 HP

Yes i ment power Mosfet.Sorry

I see usualy IGBT are for 800+ Voltages.

I just cant calculate max power can handle. The 8A on datasheet are AVG not Rms.

Hi, At what frequency are you going to switch the mosfets to get your 3phase AC?

Tom...... :)

Its on 31kHz using SVPWM techique.



You will need at least 800V devices for a 230Vac input.
DC bus voltage = 230 * 1.414 = 325Vdc
When you develop the 3phase you will need more than twice that Vds.
In practice 800V is a minimum for 230Vac
Usually it is 1000V and an IGBT bridge package as Lafred has posted.

Tom… :slight_smile:

Many 3 phase inverters i saw with 1 Phase line input are using that Volt range mosfets.

Can you explain more what u mean?I dont see how the Vds_max can be above 325 V.

Legolas69: Yes i ment power Mosfet.Sorry

I see usualy IGBT are for 800+ Voltages.

I just cant calculate max power can handle. The 8A on datasheet are AVG not Rms.

IGBTs usually come in 600V breakdown and 1200V breakdown. The 600V breakdown ones are good for normal mains (single and 3-phase), 1200V used for higher voltage industrial use. You'd never expose a 600V device to anything like 600V in normal operation BTW.

As I said with high voltages IGBTs are much more robust than MOSFETs and that's why you never see MOSFETs being used at high voltages any more commercially, even though they perform better. The fixed forward voltage of IGBTs and the slower siwtching means they have higher losses, but ruggedness is more important in the real world.

Yeah i read an article time ago about +/- of both IGBT/Mosfet.That's why i choose mosfet.With 3 PWM signals are on 31kHz.

( with 16 MHz Oscilator that the only frequency i can have >20kHz... cause i need 3 PWM signals on Phase Correct mode and with mega32 i have many limits..)

Something last, since i can have V/F control by software. I could still run the cheap motor but with lower torque/speed right (that fackin 1phase input for inverter is realy confusing me, but thats the only voltage i can have on home);


Power : 0,25 hp RPM : 1500 rpm/min Volt : 380 V 3-phase

Going with MOSFET’s you’ll need to learn about ways to protect against dV/dt and dI/dt
failure modes, and in general be spending more of your design on protection circuitry.

Power is Vrms x Irms, times 3 for 3 phases. With MOSFETs normally the limit is the
device dissipation. IGBT’s have a harder upper limit for current I believe.

Mark every answer you post is f**n clear and short.