An electromechanical actuator for a transport aircraft spoiler surface

The More Electric Aircraft Initiative (MEI) embraces the concept of utilizing electrical power for driving aircraft subsystems. Power electronics and motor drives are essential elements of the MEI. Advancements in power semiconductor devices, capacitors, and integrated circuits for control has enabled high density, reliable power electronic and motor drive systems for the MEI. Wright Laboratory and Sundstrand Aerospace have been working on the development of an electromechanical actuator to be compatible with the requirements of a spoiler for a typical transport aircraft. The focus of this development effort is in the motor drive, meaning the controller, inverter and motor utilized to control the actuator. Efforts are underway to increase the power density of the motor drive to achieve 1 kW/lb, with an efficiency of greater than 80%. This paper discusses the design criteria and some of the trade-offs that were accomplished during this development. This work includes the use of a novel soft switched inverter driving a five-phase switched reluctance motor. A digital signal processing (DSP) chip is utilized for responsive controls and field programmable gate arrays (FPGA) to reduce size and increase control electronics reliability. A power electronics module is developed which is comprised of insulated gate bipolar transistor (IGBT) inverter switches, diodes, a current sensor and gate drives. The thermal management system utilizes a reflux heat exchanger with integral phase change material that will enable the motor drive to operate in the environment of the actuator.