Regenerated power fed from a rotary electric machine is immediately reduced where connection between an electric machine and a DC power source is blocked. An inverter control section controls the inverter by controlling an armature current in a two-axis orthogonal coordinate system that rotates in synchronization with the rotary electric machine, the armature current being a vector obtained by synthesizing a field current and a drive current extending along respective axes of the orthogonal coordinate system. If it is determined that connection between the DC power source section and the inverter is in a blocked state, the inverter control section executes zero-torque control in which the inverter is controlled such that torque regenerated by the rotary electric machine becomes zero, and executes high-loss control in which the field current is varied so as to increase the armature current while maintaining a torque command provided in the zero-torque control.