Control Design under Limitation of Motor Current for Electric Fuel Metering System with Redundancy on Aircraft Electrification

Aircraft electrification is one of technological innovations to achieve the goal of CO₂ emission reduction in civil aviation. In present research, we focus ourselves on an Electric Fuel Metering System (EFMS). Aircraft systems are commonly expected to make not only simplified configuration and improvement of controllability, but also safety and reliability. The electrification of fuel system also requires the similar approach. Therefore, a simple and reliable redundancy concept is a crucial challenge. In addition, stable and responsive controllability that does not affect engine operation is required, especially in fuel system, it is desired to achieve both accurate metering and short settling time without overshoot or undershoot. However, in such a system, the response is nonlinear due to the fuel flow circuit and the motor drive during current limiting. Systemizing a control design that takes these constraints into considerations and that satisfies the requirements over a large dynamic range, has not been discussed. This paper discusses a design methodology to achieve optimal fuel flow control in the EFMS with redundant electric fuel pumps, considering motor current limitation by current limiters. The flow control model is created by adding the flow command increment limiter estimated as equivalent to the current limiter. Using this model, the gain characteristic map is derived analytically. The control system is extended to an active-active control redundant system. The compensating action of that system ensures that if one of the fuel pumps suddenly shut down, the remaining fuel pumps will autonomously increase their flows to maintain the required flow for the engine fuel burn.