I was looking at this site http://www.electronics-tutorials.ws/power/insulated-gate-bipolar-transistor.html
Here an IGBT is an NMOS with a BJT> But the BJT looks to be a pnp device. When the NMOS turns on, Vbe =0 , how will the pnp conduct? Making the gate negative, mean no channel exists in the NMOS, and the NMOS is off. The 2 ends could actually be at any potential. How does this circuit actually work?