Can I repace power transistor with MOSFET ??

[Sikander Khwaja]

Hi fellows !!!!
I need som help bout using MOSFET in place of BJT in DC - AC Invertors / UPS Currently am using D313, 2N3055 & som other NPN power transistors with 2.5Vbe I tried to use IRFP260 the same way but its not even conducting kindly help me out if it has any different way of operating or any important / basic point.
Waiting for a positive response
Regards,
SK

 

[Loq]

Power Mosfet have to be used in their ohmic region. The gate voltage Vgs you apply have to be high enough compared to Vds to be in this region, following the next formula Vds<Vgsoff. For the IRF260 the Vgsoff is between 2 and 4V as said in the ds then I think you are working in the active region where Id depends only from Vgs and Vgs is small. You'd better to use a power mosfet driver to generate correct Vgs. Good luck.

 

[VVV]

Since the MOSFET needs a much higher voltage between G and S than does the BJT, most likely you are not driving them correctly.

First, identify the resistors that were placed between the B and E of the BJT's and replace them with much higher values, to allow the G-S voltage to increase.

Also, you may need to check the supply voltage of the driving circuit, and if possible increase it to 10-12V.

 

[Sikander Khwaja]

Thanx guys for ur valuable advices do send me som more related stuff if posssssible.......
SK

 

[supra924]

Yes youcan.
The main advantage is to get only dynamic power and dynamic power will bw less ,switching regulation will be higher !