HPEM technological research program proposed the integration of emerging permanent magnet motor and position sensor technologies in high power density, fault tolerant actuator designs which could be an integral part of a rotorcraft swashplate electromechanical actuation system with superior dynamic response and fault ride through capability. Innovative permanent magnet and insulating material technologies, involving particular Neodymium alloy permanent magnet materials with small substitution for iron by Cobalt enabling to substantially improve high temperature performance as well as specially enameled winding wires treated through vacuum pressure impregnation techniques, respectively, in conjunction with design optimization methodologies based on embedded permanent magnet topologies are going to be applied at the program operational level.
The HPEM project was divided in three Work Packages. WP1 was oriented to the better understanding of the specifications and the validation plan through motor and sensor preliminary design and pilot hardware manufacturing. WP2 was the project core development that covers critical design of motor and sensor modules resulting in the proposal of two alternative configurations and delivery of respective prototypes. Embedded permanent magnet and flux-switching topologies as well as photo-diode, photo-transistor and Hall effect sensor formulations are going to be evaluated on the basis of performance and reliability requirements. Finally, WP3 covered manufacturing and testing of the remaining twelve prototypes to be delivered. During this WP all specific test benches will be developed so that the technological readiness level expected will be certified.
HPEM project success could allow safer aeronautic transports as well as size and weight reduction of generation equipment. Significant reduction in maintenance and overall environmental impacts is expected to be achieved too.
The aim of the HPEM project was the study, design and construction of ten motor and sensor prototype parts for particular actuators involving high performance specifications for aerospace applications.
In a first phase the preliminary design had been performed including the selection of appropriate materials, configurations and technologies enabling to meet the desirable requirements. During this phase particular Silicium Cobalt iron laminations (Vacoflux50 with width 0.35 mm) had been selected for the magnetic circuits providing high saturation magnetization and reduced losses. Furthermore two alternative motor configurations, involving axial and circumferential segmentations respectively, had been compared by performing design sensitivities through electromagnetic modelling by 2D finite element techniques in order to obtain the optimal values of the key geometrical and operating parameters and then the calculated electromagnetic performance and thermal characteristics had been assessed. The optimised configuration selected is the circumferentially segmented one, mainly due to its better thermal characteristics.
In a second phase the critical design had been performed, by selecting adequate insulating materials enabling temperature withstand up to 200 oC, implementing mica based components, windings composed of specially enamelled with aromatic Polyimide round copper wires, mica reinforced Nomex slot insulations and Samarium Cobalt alloy permanent magnets. Moreover, an appropriate resolver technology has been proposed presenting robust design and the increased thermal endurance for the rotor speed and position sensing (Rotasyn RO2010-K-R004 type), which demonstrated satisfactory performance under all the considered operating conditions for this application. It may be noted that at the validation stage of the constructed parts of the prototype, appropriate adaptations and reconstructions had been performed due to difficulties encountered both on procurement procedures and on the implementation of newly defined technologies, involving rotor parts with Halbach array reconstruction as well as copper density modification in slots of stator parts. The critical design stage, including the above mentioned adaptations with respect to the preliminary design outcomes and the successful acceptance tests of the two delivered actuators, had been finalised.
Finally the remaining eight motors had been extensively tested and after assessing their compliance with all characteristics of the defined operating conditions they have been delivered. Furthermore, in order to overcome some problems encountered after the mechanical assembly concerning the machine-converter coupling appropriate fitting and the harness of the mechanism driven by the delivered machines due to dynamic loading characteristics, specific corrective actions had been proposed.