Bias free adaptive exponential notch filter with low constant delay

Conventional adaptive notch filter based on an infinite impulse response (IIR) filter is well known. However, the IIR adaptive notch filter has a problem of stability due to an IIR filter and bias error due to disturbance. The adaptive notch filter using Fourier sine series (ANFF) is therefore proposed as a stable adaptive notch filter with bias free adaptive algorithm. However, there are problems of the constant delay and low convergence rate due to the large term numbers of series expansion. In this paper, the structure of the notch filter is proposed to decrease the constant delay and improve the convergence rate.