Step-down Three-phase Power Factor Correction For Aircraft

More electric aircraft(MEA) apply variable speed variable frequency power to aircraft power system in order to reduce self-weight and improve utilizing efficiency for energy sources. Lots of power electronics devices will be used in aircraft power system, then, aircraft power quality has beeen paid attention by aircraft filed. So aircraft filed revise the aircraft power standard successively, and proposed stricter demand. Firstly, This paper summarizes the sequential change of aircraft power standard DO-160, and point out the special demand of designing aircraft three-phase power factor correction(PFC), which include step-down topology, better performance of suppressing harmonic in high and changing frequency ,steadier dc-output voltage and smaller waveform in wide and asymmetric power source voltage.This paper proposes applying generalized active power filter(APF) to aircraft three-phase PFC to realize step-down demand. It also has the advantages of better performance of suppressing harmonic and smaller power capacity processed by active power switch comparing with traditional shunt APF and pulse width modulation rectifier. This paper also proposes input current amplitude-phase control method to steady dc-output voltage. Then establishes mathematical model for step-down three-phase PFC with controllable output voltage for aircraft, designs controller of voltage-loop and current-loop. Besides, it verifies performance of suppressing harmonic and steady control of dc-output voltage by simulation.Ac-power source frequency in MEA is changing between 360Hz to 800Hz. The premise of controlling aircraft three-phase converter needs to extract the grid synchronized signals exactly and rapidly. This paper applies adaptive notch filter in extracting synchronized signals for variable frequency aircraft three-phase power, and constructs the differential equations and schematic diagram of extracting synchronization with ANF inαβstatic coordinate according to instantaneous symmetrical component inαβstatic coordinate. This new method can decompose the positive and negative sequence fundamental component exactly and rapidly. This proposed method with ANF inαβstatic coordinate can reduce 1/3 calculation burden compared with the original ANF method in three-phase abc static coordinate. The algorithm is implemented in filed programmable gate array, and the calculating time is only 115ns.This paper analyzes quantitatively relationship of power factor, inverter's compensation capacity and circuit parameters to the problem of controlling dc-output voltage steady affects power factor and inverter's compensation capacity. Then, according to above relationship it designs the inductor near power sourse and the inductor near uncontrolled rectifier. Finally, verifying the above theoretical analysis by simulating.At last, it designs 2kW-experimental prototype with numerical control. It experiments on proposed mothed of extracting synchronized signals in various working conditions demanded by aircraft power standard. Experimental result indicates that the mothed has better dynamic performance.