ELECTRIC MACHINE SYSTEM

The electric machine system includes an electric machine having a rotor and a coil; the power converter that outputs an output current to the coil of the electric machine; and a controller that controls the power converter. The controller includes a signal output unit that outputs a signal for controlling a mode of the output current to the power converter; and an abnormality detection unit that receives an abnormality signal indicating an abnormal situation in a case of the abnormal situation in which the generation of the fault current generated in the coil by the rotation of the rotor should be suppressed. The signal output unit outputs a demagnetization control signal to the power converter when the abnormality detection unit receives the abnormality signal. The power converter causes a demagnetization current for a demagnetization magnetic flux that demagnetizes the permanent magnet of the rotor to flow through the coil in response to an input of the demagnetization control signal.