Load profile testing of a permanent magnet synchronous machine EMA

With the continuing advancement of brushless permanent magnet machines and power electronics, high-power electromechanical actuators (EMAs) are becoming contenders in applications historically serviced by hydraulic devices. However, research and development efforts must continue to address several critical issues before EMA technology can be labeled mature in the high-power arena. Within this paper, a test stand designed for actuator performance testing under load is discussed, and several tests are summarized in response to a first look the impact of employing a two-phase on motor drive in conjunction with a permanent magnet synchronous motor. While the permanent magnet synchronous machine is more common and less costly than the brushless DC machine, the two-phase on drive is simpler and requires a much less complex control system than that required for a three-phase on sinusoidal drive. Hence, the two are often used simultaneously. The impact of the resulting torque ripple on EMA performance is governed not only by the actuator itself, but by the dynamics of the load profile as well. Hence, the suitability of the combination is application specific. Test data, with a focus on the application of thrust vector control for the Space Shuttle main engine, is presented. The data indicates that operation with a two-phase on drive provides acceptable performance in this specific application