FADEC

全权限数字发动机控制器

FADEC是全权限数字发动机控制器，为了增加发动机的可靠性和效率，当和飞机的分系统结合操作时，全权限数字式发动机控制（FADEC）提供发动机控制的全权限来达到稳定和瞬态的发动机特性。

发展历史

20世纪70年代初，英国开始研制数字式电子控制(FADEC)系统。继而，美国等国家也纷纷进入，美国后来居上，一直处于比较领先的地位。

20世纪80年代初，中国才真正展开高性能推进系统数字控制的研究,已初步掌握了各项关键技术，但总体来说，尚处于技术突破阶段。

产品特色

全权限数字发动机控制器（Full Authority Digital Engine Control）FADEC,是相对于传统的发动机液压控制系统来说的。传统的液压控制系统实现控制规律算法主要依靠凸轮的空间曲面来完成，而这个空间曲面构型制造比较困难，因而液压控制系统控制精度不高。FADEC实现控制规律算法则简单的多，只需把公式变成代码进行处理即可，因而控制精度要高很多。

系统组成

以发动机V2500为例

FADEC系统有双通道的EEC和以下的外部设备:

-燃油计量组件（FMU）

-专门的FADEC交流发电机

-压气机控制系统

-间隙控制系统

-起动系统（起动机关断活门、点火激发器）

-反推系统

-热管理系统

-发动机传感器

-电气导线系列

发展趋势

航空发动机控制正处于从传统的液压机械式控制向数字电子控制的转变阶段，并且经历了从单个部件到整体、从模拟式到数字式、从有限功能到全权控制的发展过程。可以预测，无论在军用机上，还是在民用机、直升机乃至航机陆用装置上，今后将越来越多地采用发动机电子控制系统，尤其是全权限数字电子控制系统，将使航空发动机控制技术达到更新、更高的水平。

FADEC将继续在系统硬件可靠性、先进的故障检测技术、准确一致的维护信息和新的控制规律等方面发展。可能会采用纤维光缆进行数据通信，同时还可能会使用光电的FADEC加上发动机稳定性的主动控制、一体的起动机/发电机、电磁作动器、分布控制电子部件、一体的环境控制系统、稳定性引气和放气、按需要控制的燃油泵、电磁转子轴承、闭环主动间隙控制等，使发动机效率更高，并简化外部部件、减轻质量、延长使用寿命。

A typical civilian transport aircraft flight may illustrate the function of a FADEC. The flight crew first enters flight data such as wind conditions,runwaylength, or cruise altitude, into theflight management system(FMS). The FMS uses this data to calculate power settings for different phases of the flight. At takeoff, the flight crew advances the throttle to a predetermined setting, or opts for an auto-throttle takeoff if available. The FADECs now apply the calculated takeoff thrust setting by sending an electronic signal to the engines; there is no direct linkage to open fuel flow. This procedure can be repeated for any other phase of flight.

In flight, small changes in operation are constantly made to maintain efficiency. Maximum thrust is available for emergency situations if the throttle is advanced to full, but limitations can’t be exceeded; the flight crew has no means of manually overriding the FADEC

True full authority digital engine controls have no form of manual override available, placing full authority over the operating parameters of the engine in the hands of the computer. If a total FADEC failure occurs, the engine fails. If the engine is controlled digitally and electronically but allows for manual override, it is considered solely an EEC orECU. An EEC, though a component of a FADEC, is not by itself FADEC. When standing alone, the EEC makes all of the decisions until the pilot wishes to intervene.

FADEC works by receiving multiple input variables of the current flight condition includingair density, throttle lever position, engine temperatures, engine pressures, and many other parameters. The inputs are received by the EEC and analyzed up to 70 times per second. Engine operating parameters such as fuel flow, stator vane position,bleed valveposition, and others are computed from this data and applied as appropriate. FADEC also controls engine starting and restarting. The FADEC's basic purpose is to provide optimum engine efficiency for a given flight condition.

FADEC not only provides for efficient engine operation, it also allows the manufacturer to program engine limitations and receive engine health and maintenance reports. For example, to avoid exceeding a certain engine temperature, the FADEC can be programmed to automatically take the necessary measures without pilot intervention.

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