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针对传统低通滤波器在脉冲宽度调制(PWM,Pulse Width Modulation)开关功放电流降噪过程中存在去噪效果与系统带宽难以兼顾的问题,提出了一种基于提升小波变换的功放电流实时降噪法.首先基于d B4提升小波算法,采用滑动数据窗、对称边界拓展和阈值法强制降噪等相结合的方案实现对功放电流的实时降噪.然后根据不同小波分解层数对系统截止频率的影响,确定合适的小波分解层数.实验证明,提升小波实时降噪算法既可以有效地滤除功放电流噪声,又对系统带宽和相角滞后影响较小,非常适用于对实时性和信噪比都有较高要求的磁悬浮高速转子系统.
Aiming at the problem that the conventional low-pass filter has the disadvantage of denoising effect and system bandwidth in the pulse-width modulation (PWM) switching power amplifier current noise reduction process, a real-time power amplifier noise reduction based on lifting wavelet transform Method.At first, based on the d B4 lifting wavelet algorithm, a sliding data window, symmetric boundary expansion and threshold noise reduction are combined to realize real-time noise reduction of the amplifier current.And then, according to different wavelet decomposition layers, the cut-off frequency of the system And determine the appropriate layer number of wavelet decomposition.Experiments show that lifting wavelet real-time noise reduction algorithm can not only effectively filter out the power amplifier current noise, but also have little effect on the system bandwidth and phase angle lag, which is very suitable for real-time and signal noise Magnetic levitation high-speed rotor system has higher requirements than all.