基于对数域模拟CMOS连续小波变换电路的谐波检测方法

A Novel Method for Harmonic Detection Based on CMOS Log-domain Continuous Wavelet Transform Circuit

电力谐波检测小波分析方法大都在微机或数字信号处理器上用软件方式实现,计算量大导致实时性差;需A/D转换,增加了检测仪的功耗与体积,工作频率范围窄。针对该问题提出了基于低电压、低功耗对数域Morlet连续小波变换电路的谐波检测方法,用模拟CMOSVLSI电路对谐波电流进行Morlet连续小波变换,以硬件方式实现谐波检测。小波变换电路由冲激响应为Morlet小波的模拟滤波器组构成,其传输函数用非线性最小二乘法求得,以CMOS对数域积分器为积木块对滤波器进行综合。通过调整积分器的偏置电流来改变小波变换的尺度因子,从而实现各种谐波成分的检测。SPICE仿真结果表明了该方法的可行性。

The wavelet-based harmonic detection algorithm is mostly programmed in PC or DSP. Because of high computational cost as well as requiring analog-to-digital converter, it＇s difficult for harmonic detection instrument to operate in real time and wide frequency range. The power consumption is also high. A novel method based on low- voltage and low-power consumption log-domain continuous Morlet wavelet transform circuits is presented for harmonic detection. To measure harmonics, the wavelet transform of harmonic signal is performed by analog CMOS VLSI composed of analog filter bank, whose impulse response is Modet wavelet. Nonlinear least square method is employed to obtain the transfer function of the filter with CMOS log-domain integrators as main building blocks. By changing the values of integrators＇ bias currents, wavelet transforms of harmonic signal at various scales can be performed. SPICE simulation results show that the method is feasible.