An electric power system for supplying power to a permanent magnet electric machine includes a high-voltage DC power source that is disposed to supply electric power to a front-end converter connected via a high-voltage DC bus to an electric inverter that is connected to the electric machine. A method for operating a control system includes monitoring the electric machine. Upon detecting a fault associated with the electric machine, a controller commands operation of the front-end converter to generate a voltage level on the high-voltage DC bus that is a maximum setpoint voltage level and monitors back-emf voltage level from the electric machine. The inverter is controlled to a three-phase open state when the back-emf voltage level is less than the maximum setpoint voltage level. The inverter is controlled to a three-phase short state when the back-emf voltage level is greater than the maximum setpoint voltage level.