I am fighting to understand how permanent magnets are inserted in magnetic equivalent circuits. In the image below is an example, at the left, the physical representation of an Iron core with a permanent magnet and air gap, at the right, the supposedly magnetic equivalent circuit of a permanent magnet.
Now, when I apply the kirchoff voltage law I know I have to get
H_Fe L_Fe + H_g L_g + H_m L_m = 0
but then why doesn't the magnetic reluctance R_m appear in the voltage law? For me, it would be
H_Fe L_Fe + H_g L_g + H_m L_m + R_m FI = 0
why doesn't the last term appear on the voltage law?