Contoller a powerful generator

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filjoa

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Hi

I try controller speed of generator with PWM.

This generator is an 3phase generator and on max rotation it produce 320V DC(after rectifying).

I have connected on generator a resistor (10R/150W), controller by mosfet IRFP456.

This is my circuit:
**broken link removed**

where have write "Resitor" is resistor 10R 150W
where have write "Motor" is my generator 3phase

But the problem stay on mosfet heats, I have one big cooler when but when generate more power with generator and mofest burn.

Someone have other suggestion to controller this generator with PWM? I think need something more powerful than my circuit, but I don’t have more ideas.

Best regards,
Filipe Abrantes
 

Ordinary mosfet like IRFP need 10V at VGS

for 5V, you need use a logic level mosfet

RDS(on) is too high with IRFP and VGS=5V, so IRFP is heat
 

Hi

thanks for quickly reply.

but I read on datasheet and Vgs(th) is on min=2, on typ=3 and on max=4 don't is this the voltage necessary to active this mosfet?

if it stay work with 5V from my PIC, way it heat if voltage is litle? I don't understand this.

is possible you explain me more cause of my mosfet heat?

best regards,
Filipe Abrantes
 

hi filjoa
i see in ur drawing u use R4 1ohm res as current sense and use R9&C11 as low pass filter but not used that signal i mean voltage accros c11 its proportional to
current through R4

u drive the gate with pulse of 5v vp but current in 1ohm resister will pull up the
voltage of source for irfp460 if u have 1Amper peak pulse then u have 1volt
2 amper uhave 2 volt and like that ur irfp460 will not act as ideal switch that
will rise temperature in irfp460....... tray to reduce 1ohm resistore to 0.1ohm
 

Hi

I buy a driver because when I put osciloscop on the GATE I don't see square wave, and I think witch stay there my problem...

with driver I'll put on gate 12V with 150mA to try have an square wave on gate.

thanks for sugestions.
 

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