26 I E E E E l e c t r i f i c ati o n M agaz ine / december 2014 Engine Characteristics Torque Reference Speed Reference + - Speed Control Motor Wound-Rotor Synchronous Motor Characteristics Performs Real-Time Simulation Using HIL Fan Torque Reference + - Torque Control Motor Wound-Rotor Synchronous Motor Observer Speed Simulink Model and dSPACE Control System Generator Characteristics and Load Generator Observer Torque Figure 3. A single line of an electric grid with feedback architecture of speed control and torque control. Speed Reference + + - - Engine Observer (Subsystem Model) Torque Control Generator Rectifier, Bus, and Inverter All Grid Components Can Be Represented by Torque and Speed Generator Speed Control Speed Turboshaft Engine Turboshaft Engine Rectifier, Bus, and Inverter How Can Small Motors Emulate an Electric Power Grid? Fan Maps and Flight Conditions Fan Observer (Subsystem Model) Torque Fan