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The development of electromechanical actuators (EMAs) is the key technology to build an all-electric aircraft. One of the greatest hurdles to replacing all hydraulic actuators on an aircraft with EMAs is the acquisition, transport and rejection of waste heat generated within the EMAs. The absence of hydraulic fluids removes an attractive and effective means of acquiring and transporting the heat. To address thermal management under limited cooling options, accurate spatial and temporal information on heat generation must be obtained and carefully monitored. In military aircraft, the heat loads of EMAs are highly transient and localized. Consequently, a FEA-based thermal model should have high spatial and temporal resolution. This requires tremendous calculation resources if a whole flight mission simulation is needed. A lumped node thermal network is therefore needed which can correctly identify the hot spot locations and can perform the calculations in a much shorter time.

A commercial electromechanical actuator (EMA) is to be dynamically tested with predetermined stroke and load profiles for transient thermal and electric power behavior to validate a numerical model used for aerospace applications. The EMA will follow the stroke profile representative of a real aircraft mission duty cycle. A hydraulic press will exert a corresponding load profile onto the EMA. Specialized hydraulic load control methods must be employed to meet the accuracy requirements. Two of these methods are closed-loop linearization (CLL) and displacement induced disturbance cancellation (DIDC). These methods are implemented along with an external PID compensator, and run in real-time in a series of system identification experiments to observe controller performance.

This paper describes the integrated modeling of a permanent magnet (PM) motor used in an electromechanical actuator (EMA). A nonlinear, lumped-element motor electric model is detailed. The parameters, including nonlinear inductance, rotor flux linkage, and thermal resistances, and capacitances, are tuned using FEM models of a real, commercial motor. The field-oriented control (FOC) scheme and the lumped-element thermal model are also described.

Electric generators have higher power density when the operating speed is increased. High speed electric generators direct coupled to gas turbines provide an ideal source of electric power for airborne applications because of reliable operation and high power density. To function reliably in the speed range of 60000 RPM to 120000 RPM, the rotor of the electric generator must be robust. Examples of the robust rotor technologies for the generator include: permanent magnet (PM), induction and switched reluctance. The objective of the present paper is to describe the current activities in the field of high speed induction generators and associated controllers. A range of induction generators and controllers rated from 5 kW to 200 kW operating at speeds to 62000 RPM is currently under development. The rotor is designed using high strength magnetic materials for the magnetic paths, and high strength alloys for the conductors that form the squirrel cage.

High speed generators offer very high power density solution for electric power requirements in airborne applications. Induction generators are suitable for the high speed environment because of the ability to provide controlled voltage and power output with a reliable rotor construction. An important issue of power control for the high speed induction generator is maintenance of the steady state output voltage within the specified limits over the entire range of speed and load variations. This paper discusses the development of a closed loop control system for a 200 kW induction generator under different load conditions. Field Oriented Control (FOC) schemes are implemented to both operate the generator in the maximum torque conditions available and to decouple the maximum torque from the field under transient and steady state operation. FOC uses Classical Proportional and Integral (PI) controllers for regulation because of their simple implementation.

The magnetic bearing control system development and integrated system test results are presented for a high speed, high power Switched Reluctance Machine (SRM) Starter/Generator (S/G). The SRM rotor is suspended on magnetic bearings in a single shaft gearless/oilless configuration operating at 42,000 RPM. The SRM sub-system consists of a 6/4-pole machine with dual-power inverters rated at 250 KW (max), 270Vdc with split bus configuration. The magnetic bearing sub-system actively controls the rotor position in five axes (four radials and one axial). The bearing subsystem consists of homo-polar type magnetic bearing actuators with permanent magnet (PM) bias, inductive position sensors, DSP-based embedded controller and PWM current drivers for each control axis. The development and implementation of Single Input Single Output (SISO) and Modal control laws are presented.