HELP PLEASE!! for Half phase bridge..

[moonman]

Hi there,

I am just trying to learn how an half phase bridge work. I built one using 6 nmos's on breadboard but for some reason.. even though i havnt connected the gates.. my psu shows a short :s.... is there any logical reason behind it??

then i went in to LT- spice (shown in attachment)... drew it up.. and it gives me weird results there aswell... regardless of the gates connected or nt.. there is always a voltage at the points where by A, B, C outputs are... so i cant create an High Low effect... which eventually i need to drive my BLDC..

so please share some advice in this matter ... on how to get ride of the short on psu.. and how to simulate it.. im using LT-spice for simulations

 

[keith1200rs]

You should be using PMOS for the top transistors of each half bridge. The PMOS gate voltage needs to be 15V, relative to the 0V to turn them off.

Keith