The permanent magnet induction generator (PMIG) is a new type of induction generator (IG) that has a permanent magnet (PM) rotor inside a squirrel cage rotor. The squirrel cage rotor is linked to the shaft, and the built-in PM rotor is free to rotate against the shaft. One of the notable features of the PMIG is that the power density is higher compared to a conventional IG. In this paper, the effects of the built-in PM rotor on the equivalent circuit parameters are investigated to clarify the reason for the increased power density.