A power inversion and control system for a supersonic closed cycle disk MHD generator, using a current source PWM inverter, is considered, and its performance is confirmed through numerical simulations for a model system in which the MHD generator with 100 MW thermal input and 40 MW electrical output, using cesium seeded helium plasma, is connected to the electric power system, expressed by the infinite bus, via the power inversion and control system and the power transmission line. It is made clear that the system can stably and steadily transmit the nominal electric power from the MHD generator to the electric power system under the nominal operating condition. The system is robust for the change of the a.c. side voltage, and the nominal operation of the MHD generator can be kept, even in the case of voltage fluctuation. It is also made clear that the active and reactive power provided to the electric power system stably and steadily trace the change of their set values, indicating the excellent power control performance of the system.