Abstract: A turbogenerator/motor controller with a microprocessor based inverter having multiple modes of operation with an energy storage and discharge system including an ancillary electric storage device, such as a battery, connected to the generator controller through control electronics. Electrical energy can flow from the ancillary electric storage device to the turbogenerator controller during start up and increasing load and vice versa during self-sustained operation of the turbogenerator. When utility power is unavailable, the ancillary electric storage device can provide the power required to start the turbogenerator. When a load transient occurs, the gas turbine engine and the ancillary electric storage device provide the power required to successfully meet the transient.