Research On Transients Suppression For Avionics Dc Power Supply

Electronic Controller is the primary part in aero-engine control system, and its role is gathering data from engine and control system, acting in compliance with laws and algorithms, and controlling the engine operation. The power module is a very important part of electronic Controller, and it must feed power to electronic Controller reliably so that electronic Controller can run successfully. Once some malfunction happens to power module, electronic Controller will not work in good operation, which will lead to serious accident. Usually, there are under-voltage and transients in avionics dc power supply for electronic Controller, also EMI is included. The power module of electronic Controller must suppress transients addressed above.This thesis designs a circuit for lifting under-voltage and suppressing transients in avionics dc power supply. Transients suppression is either under-voltage lifting or over-voltage step-down, so buck and boost are selected to cascaded to form transients suppression circuit. Considering the characteristic of input voltage, this paper designs controlling strategy, discusses the approaches of improving efficiency and decreasing the volume and weight. A prototype with 300W output is fabricated and tested.This paper also designs circuit for suppressing peak voltage by taking the characteristic of peak voltage into account. A shunt capacitor is selected, and a small inductor is needed to suppress peak current accordingly. Instability may occur by introducing peak voltage suppressing circuit in front of transient suppression circuit designed above, so the problems are analysed, and peak voltage suppressing circuit is modified, if necessary.At the end of the paper, EMI noises in transient suppressing circuit are analysed. Equivalent circuits of common mode and difference mode in various operation types of transient suppressing circuit are got by analysing EMI nosies causes and propagation path. Comparing noises in various woking types in virtue of equivalent circuits, which will provide theoretical basis for designing EMI filter.