Management of Regenerated Energy in Electro-Mechanical Actuators for Aerospace Application

Electro-mechanical actuation systems are becoming more common in aerospace applications. Systems that have been traditionally based on hydraulic-mechanical (HM) actuators are now being replaced by electro-mechanical actuation systems in pursuit of the more electric airplane. The actuator's primary purpose is to convert energy (hydraulic or electrical) to mechanical energy and this operating mode occupies the primary design focus. A secondary design concern is the conversion of mechanical energy back into hydraulic or electrical energy. This energy results from potential and kinetic energy stored in the mechanical system during actuation. A portion of this energy flows back through the actuator towards the source. In the case of HM actuation, the management of this energy is well understood. In electro-mechanical actuation systems, this energy is commonly referred to as regenerated energy or regen for short. Regen can be destructive to the electro-mechanical actuator (EMA) motor drive electronics (MDE). It can also require additional circuitry that adds significant size, cost, and complexity to the product. This impact is non-value additive to the primary benefit of actuation, and therefore needs to be minimized. The optimum management of this energy to maximize value is not well understood.

This paper describes a method to characterize the actuation system and implements this characterization in a computer based model. The sources of potential energy in the mechanical system are described. Five regen operating modes are defined, two of which are EMA based, and three of which are distribution bus based. The model is applied to a test case with a representative EMA, and the two EMA based regen management modes are studied. Based on this study, the strengths and weaknesses of both approaches are presented.