Thread Subject: asynchronous machine modeling

Dear all,
im trying to model a asynchronous machine (wound rotor induction machine) as a generator. this is similar to a double fed generator but its not connected to the grid, im using a dc voltage source as supply to a inverter which is fed to the rotor side and resistance-inductor load connected to the stator side. the the frequency responce is fine, while the voltage output is not. as i increased or decrease the speed(mechanical input to the machine) there is no changes in the output voltage. i dont know where the problem lies, i need some help to identify what i shall do.