Protect Mosfet in inverter circuit

[Nitesh Kamal]

Dear Sir

In my inverter there is a IC Sg3524(16 pin ic) used for osscilation & pin 11 & pin 14 used for Mos drive voltage, as we know when these voltage has any type of difference then mosfet is blow out.

Plz suggest me to some modification in circuit if any voltage diffrence found in both mos drive voltage then sg3524 stop the oscillation.

plz advise

 

[barry]

Maybe if you posted a schematic of your circuit....

 

[eiphan]

Dear Sir

In my inverter there is a IC Sg3524(16 pin ic) used for osscilation & pin 11 & pin 14 used for Mos drive voltage, as we know when these voltage has any type of difference then mosfet is blow out.

Plz suggest me to some modification in circuit if any voltage diffrence found in both mos drive voltage then sg3524 stop the oscillation.

plz advise

Perhaps considering zener for simple. But yes, if you have shown circuit, it would be better.

 

[Nitesh Kamal]

Perhaps considering zener for simple. But yes, if you have shown circuit, it would be better.

see the attached file

 

[KerimF]

Sorry, but isn't it a rather complicated solution to build a simple 50Hz push-pull inverter using N-MOSFET!

I wonder how my 'very' simple driver (2 NPN transistors and a few resistors) works without failure unless the user connects, by mistake, the mains powerline to the transformer output. To control the bases of the 2 transistors I used the MCU AT89C2051 (available in the local market). But since the MCU takes a short boot time to run properly, the Vcc of the driver (the 2 NPN transistors) is delayed by a PNP transistor and a capacitor.

The advantages of using an MCU in this case:
(1) The frequency is stable since it is based on the MCU crystal frequency.
(2) It can provide a soft start at boot by varying the duty cycle from almost 0 to D_C maximum.
(3) If the battery voltage is monitored, the duty cycle could be decreased accordingly when the battery voltage is higher than 12V for example.

For instance, I detect the current overload from monitoring the instantaneous Vds (during on state) since it increases with current and temperature.

 

[iop95]

There are not any problem if voltage levels of IC outputs are slightly different; main problem for this IC is that don't have programmable dead-time and may lead to both MOSFETs legs conduction.