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降压型航空三相功率因数校正的研究
Step-down Three-phase Power Factor Correction for Aircraft
【作者】 杨玉良;
【导师】 杜雄;
【作者基本信息】 重庆大学 , 电气工程, 2011, 硕士
【摘要】 为减轻自重,提高飞机的能源利用效率,“多电飞机”将变速变频电源系统应用到航空电源中,大量非线性电力电子装置在航空电源中得到应用,飞机电能质量问题引起了广泛关注。航空领域相继对航空电源标准进行修订,提出了更加严格的要求。本文根据航空电源标准DO-160先后的变化,总结归纳了新航空电源标准的变化,指出设计航空三相功率因数校正(PFC)的特殊要求:①.降压型;②.高、变频率条件下的高谐波抑制性能;③.宽输入和不平衡电源电压条件下直流输出电压的稳定和更小的纹波。为满足航空三相PFC降压的要求,将广义有源电力滤波器(APF)应用到航空三相PFC中。与传统并联型APF和PWM整流器相比,它还具有谐波抑制效果好、处理功率容量小的优点。针对广义APF在电源电压变化条件下直流输出电压不能稳定的问题,提出了稳定直流输出电压的输入电流幅相控制策略。建立了输出电压可控的降压型航空三相PFC的dq坐标系下的数学模型,并对电压环和电流环进行了设计。通过仿真对谐波抑制效果和直流输出电压的稳定控制进行了验证。多电飞机交流电源频率在360~800Hz之间变化,快速准确地提取变频航空电源的同步信号是航空三相变流器的控制前提。文中将自适应陷波器(ANF)应用到变频航空三相电源系统的同步信号提取中,根据αβ静止坐标系下的瞬时对称分量法,构造了用ANF提取同步信号的微分方程,并给出了实现原理框图,可以快速准确地提取出基波正序和负序分量。文中在αβ静止坐标系下的ANF算法与三相abc坐标系下的算法相比,可以减少1/3的运算量。文中提出的检测方法在FPGA中实现,运算时间仅需115ns。针对输出电压的稳定控制对功率因数和逆变桥补偿容量影响的问题,定量分析了功率因数和逆变桥补偿容量与主电路和电源运行参数之间的关系。并根据此关系,针对航空电源标准要求的电源运行工况,对电源测电感和不可控整流桥侧电感进行了详细的设计。通过仿真对以上理论分析进行了验证。设计了数字控制的2kW实验样机。利用该样机,对文中提出的同步信号提取方法就航空电源标准要求的多种运行工况下进行了实验研究,结果证明提出的同步信号提取方法具有较好的动态性能。
【Abstract】 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.