Boost converter not switching

[rragupathiraja]

Hi

I am making a Boost converter for my inverter application..
Vin - 12V
Vout - 24V

Switching frequency - 300kHZ
Duty ratio - 50%

I am generating a PWM signal of 300kHz for switching the IRFP2907 MOSFET. The Driver used between MCU and FET is TC4424..


the inductor vale is 100Micro henry and cap is 10MicroF..


The problem is the load gets the applied voltage only.. No boosting is done in between the stages. If i am giving a 300kHz switching frequency for the mosfet and checking out the Pulse level its switching waveform is irregular.. IF i am using 10kHz the FET Vds is experiencing the 10kHz switching though there is n change in the output..


Help me in this regard

thanks

---------- Post added at 10:31 ---------- Previous post was at 10:30 ----------

iam uploading the schematic but its not getting uploaded..

 

[inventor(y)]

Can you provide a schematic because we can not guess what you're doing. Keep in mind that a boost converter (any fly-back like converter) needs some kind of soft start. The error amp will drive the switch to max. duty cycle at start-up because the output voltage is equal to V-in for a boost converter and it will not get any higher then V-in (ok, minus a diode drop or whatever you have connected in series with the output capacitor.) the first time the switch is closed. The soft-start circuit is a trade-off between start-up time and input peak current during start-up.

Gr, Inventor

 

[alexan_e]

iam uploading the schematic but its not getting uploaded..

Maybe it is the extension of your file, make a zip file and upload again

Alex

 

[leo_o2]

The load is too heavy? Or your driver don't have enough driving capacity.

 

[rragupathiraja]

@Inventor, Thanks.. Finally i get out of that switching problem and converter is working fine..

 

[vimalkhanna]

The Cgs is large in value to handle 300KHz ..as the same absorbs the transitions and no switching is seen on the drain .
You shall need to pull the gate down with a discharging current to clear the gate for next pulse