An article on the electromagnetic compatibility requirements and optimization of engine controllers for the complex operating environment of carrier operations. The article is in Chinese, and a Google translation is posted below. Two of the authors are from 649 Institute (Guiyang Engine Design Institute), which is responsible for J-31/J-35's engines.
Electromagnetic compatibility optimization design of carrier aircraft engine
Optimization Design of Electromagnetic Compatibility of Carrier Aircraft Engine
Xu Ming Yin Longxiang Liu Zilong October 18, 2020
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With the increase in the detection parameters of aero engines and the continuous improvement of control functions, the circuit structure of the aero engine control system, especially the digital electronic controller, is becoming more and more complicated. The engine of the carrier-based aircraft is parked on the ship along with the aircraft. There are many high-power, high-frequency electronic equipment and cables nearby. The electromagnetic environment is complex and the electromagnetic field strength is high. The engine will encounter strong electromagnetic interference when working. In addition, in order to meet the needs of mission development, the level of digitization, automation, and intelligence of aircraft continues to increase, and the number of electronic and electrical equipment such as navigation systems, weapon systems, power systems, control systems, etc. continue to increase, the power continues to increase, and the frequency gradually rises. At the same time, for the purpose of lightweight, the aircraft uses a large number of composite materials, resulting in a reduction in the shielding performance of the aircraft body, which poses new and severe challenges to the electromagnetic compatibility of aircraft and engine systems. The electromagnetic compatibility of all electrical/electronic systems and accessories of carrier-based aircraft engines shall comply with the requirements of GJB 151B—2013 "Electromagnetic Emission and Sensitivity Requirements and Measurements for Military Equipment and Subsystems" and HJB 34A—2007 "Electromagnetic Compatibility Requirements for Ships" Regulations. The lightning protection design of engine accessories shall meet the requirements of GJB 2639-1996 "Lightning Protection for Military Aircraft". Compared with other engines, the electromagnetic compatibility requirements of carrier-based aircraft engines have increased electrostatic discharge sensitivity (CS112), 25Hz～100kHz magnetic field radiation emission (RE101) and lightning test items, and conduction sensitivity at 25Hz～150kHz power line (CS101) , Power line spike signal conduction sensitivity (CS106), 4kHz～400MHz cable bundle injection conduction sensitivity (CS114), 10kHz～100MHz cable and power line damped sinusoidal transient conduction sensitivity (CS116), 10kHz～40GHz electric field radiation sensitivity (RS103) and other projects put forward higher requirements. Therefore, carrier-based aircraft engines must be improved and optimized in terms of electrical wiring, electronic controllers, ignition systems, sensors, etc., based on the electromagnetic compatibility design of other engines, to meet relevant requirements.
Optimization of electrical wiring
In order to take into account the thrust index requirements of carrier-based aircraft engines, lightweight design of control system components is required, which often results in a compact layout of the control system on the engine and dense wiring. Compared with other engines, the electromagnetic environment of carrier-based aircraft engines also includes natural interference sources, receivers, transmitters, antennas, etc. in the sea area. The combined effect of intentional threat electromagnetic environment and unintentional background electromagnetic environment. The electrical wiring design of the carrier-based aircraft engine needs to consider the coupling suppression of low-frequency and high-frequency cables and control the common mode current. In order to ensure that the electrical wiring of the ship-based engine meets the electromagnetic compatibility design requirements, the following principles should be followed when the electrical system design is carried out: Except for the switch value, the remaining wires should be twisted-pair or triple-pair shielded wires; the wire shielding layer should pass through the anti-wave sleeve Attached with shielded tail to ensure 360° shielding continuity; engine cable shielding layer adopts single-ended grounding; high voltage wire adopts inner and outer double-layer shielding method, adopting double-ended grounding; engine cable main plug and accessory end plug use marine resistant series connectors , The tail attachment uses shielded tail attachment to ensure 360° shielding continuity; after the wires are bundled, a light anti-wave sleeve is used for protection; the bifurcation point of the engine cable is overlapped with a high temperature resistant braided jacket and selected The integrated braided anti-wave sleeve technology ensures the continuity of the shielding at the bifurcation; the wire shield is connected to the connector housing through a section of anti-wave sleeve, and the induced current of the shielding layer is safely released through the ground, and it is guided through the bracket connected to the engine To the engine shell, improve the cable anti-electromagnetic interference ability.
Optimized design of electronic controller
Due to the low maturity of the control system of the distributed architecture, the reliability cannot meet the index requirements of aeroengines. At present, most of the aeroengine full authority digital electronic control (FADEC) systems in China are typical centralized control systems. Since the electronic controller of the carrier-based aircraft collects a large number of signals and a variety of types, the signals at the electronic controller end are easily coupled to each other and introduce interference, so the electromagnetic compatibility level of the electronic controller needs to be improved. The optimized design of the electronic controller is mainly divided into grounding, filtering, lightning protection, shielding protection and other aspects.
Electronic controller grounding
A special grounding component is designed on the chassis panel for grounding connection. The +28V ground of the electronic controller and the shell ground are short-circuited at the grounding pole; all secondary power supplies in the electronic controller are grounded at a single point; digital ground and analog ground Single-point connection at the A/D converter can effectively prevent the digital circuit noise from interfering with the analog circuit and leaking to the cable; the components that need to be grounded in the shell are close to the heat-conducting plate, and the heat-conducting plate and the case maintain good electrical contact , Can reduce electromagnetic radiation.
Electronic controller filtering
Select high-performance electromagnetic interference (EMI) filters to eliminate power interference, install them close to the power outlet entrance, close to the chassis wall, to ensure a good grounding effect; design a filter circuit at the aviation plug interface to ensure good anti-interference and self-interference Filtering capacity.
Electronic controller shielding protection
The surface of aluminum alloy material parts such as box body, panel and back cover are treated with conductive oxidation, so that the surface treatment layer has a good conductive effect, and the connection resistance between the parts of the chassis is low; the chassis shell has a good anti-electromagnetic radiation effect The combination surface of the panel, cover and the box body adopts the groove plane matching structure; select the compressible sealing material with high shielding effect to seal, such as socket gaskets and chassis shielding strips to achieve good electromagnetic shielding effect; Add a transient suppressor between the sensitive circuits of the electronic controller to reduce it to the level that the circuit can withstand; improve the circuit design of the anti-damage level, select a device with certain protection, increase the overvoltage and overcurrent protection; improve the ability of the functional circuit to withstand abnormalities The hardware design adopts certain functional redundancy design and fault isolation technology to prevent the propagation of faults and avoid adverse effects on other functional circuits.
(to be continued below...)
