Generalized Comb Filter Research Articles

Enhanced Position Estimation Based on Frequency Adaptive Generalized Comb Filter for Interior Permanent Magnet Synchronous Motor Drives

Accurate rotor position estimation is critical to ensure the high-performance operation of position sensorless interior permanent magnet synchronous motor (IPMSM) drives. However, the back electromotive force (BEMF) estimated by the model-based observers is usually nonideal, which may further degrade the position estimation accuracy. In this paper, a frequency adaptive generalized comb filter (FAGCF) with a quadrature phase-locked loop (PLL) is adopted to suppress the rotor position estimation errors by filtering out the dominant distortions in the BEMF, including the (6k±1)th harmonics caused by inverter nonlinearity and flux spatial harmonics, as well as the DC offset from the inaccurate current measurements. This proposed filter is constructed by multiple digital delay blocks and therefore has the advantage of easy implementation with less online parameters tuning effort. Meanwhile, a linearized model is derived for PLL parameter design, with which the stability of the FAGCF-PLL position estimation system can also be analyzed theoretically. The effectiveness of the proposed sensorless control strategy has been validated with the experimental results on a 1.5-kW IPMSM drive.

Design of Efficient Multiplierless Modified Cosine-Based Comb Decimation Filters: Analysis and Implementation

This paper presents a computationally efficient design of modified cosine-based decimation filters. One of the main contributions of this paper is the proposal of a multiplierless finite impulse response low-order linear-phase filter to increase spurious signal rejection in the so-called folding bands. The resulting filters feature reduced computational complexity compared with other recent proposals in the literature, as well as higher folding-band attenuation than traditional comb filters. The frequency behavior of the proposed class of decimation filters is compared with generalized comb filters as well as other proposals in the recent literature. Moreover, this paper addresses field-programmable gate array implementation of the proposed filters in a variety of structures, including both nonrecursive and recursive architectures, and it evaluates and compares the performance of these architectures in terms of area and power consumption. A critical comparison is provided with the goal of highlighting key design issues and computational efficient implementations for the interested reader.

A novel two-stage nonrecursive architecture for the design of generalized comb filters

This paper presents a novel two-stage class of decimation filters with superior spurious signal rejection performance around the so-called folding bands, i.e., frequency intervals whose signals get folded down to baseband due to decimation. The key idea to enhance signal rejection in the frequency domain lies on an effective way to place the zeros of a classical comb filter in the aforementioned folding bands. On the other hand, the paper provides a mathematical framework for designing two-stage multiplierless and nonrecursive structures of the proposed filters. Examples are provided to highlight the key steps in the design of the proposed filters. Moreover, the frequency behavior of the proposed filters in both baseband and stopband is compared with classical and generalized comb filters, and a droop compensator is proposed to counteract the passband distortion of the proposed filters.

An L1 design of GCF compensation filter

This paper introduces the design of the second order GCF (Generalized Comb Filter) compensator based on L1 optimization. The problem is represented by a set of nonlinear equations solved by the Newton–Raphson algorithm. The proof of the uniqueness of the solution is also provided. One can reduce the complexity of the design approximating the original set of nonlinear equations by the set of linear equations, which depends only on the passband edge frequency ωp. A design example demonstrates the effectiveness of the proposed design.

An Economical Class of Droop-Compensated Generalized Comb Filters: Analysis and Design

In this brief, we address the design of economical recursive generalized comb filters (GCFs) by proposing an efficient technique to quantize the multipliers in the z -transfer function employing power-of-2 (PO2) terms. GCFs are efficient anti-aliasing decimation filters with improved selectivity and quantization noise rejection performance around the so-called folding bands with respect to classical comb filters. The proposed quantization technique guarantees perfect pole-zero cancelation in the rational z-transfer function of the GCFs, thus totally avoiding instability problems. Moreover, we propose the use of a simple droop compensator for the sake of recovering the passband droop distorting the useful digital signal in the baseband. A design example is proposed with the aim of showing the application of the proposed technique, and a practical architecture of a sample third-order GCF is discussed.

A General Method to Design GCF Compensation Filter

This brief addresses the design of the compensation filter of a generalized comb filter (GCF). The proposed method is general and can be applied to different design constraints, i.e., maximally flat, least square, and minimax. The coefficients of the proposed filter for all three cases can be obtained by solving two simple linear equations. The filter operates at a low rate and considerably reduces the passband droop of the GCF.

A General Method to Design GCF Compensation Filter

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> This brief addresses the design of the compensation filter of a generalized comb filter (GCF). The proposed method is general and can be applied to different design constraints, i.e., maximally flat, least square, and minimax. The coefficients of the proposed filter for all three cases can be obtained by solving two simple linear equations. The filter operates at a low rate and considerably reduces the passband droop of the GCF. </para>

On the Polyphase Decomposition for Design of Generalized Comb Decimation Filters

Generalized comb filters (GCFs) are efficient anti-aliasing decimation filters with improved selectivity and quantization noise (QN) rejection performance around the so called folding bands with respect to classical comb filters. In this paper, we address the design of GCF filters by proposing an efficient partial polyphase architecture with the aim to reduce the data rate as much as possible after the Sigma-Delta A/D conversion. We propose a mathematical framework in order to completely characterize the dependence of the frequency response of GCFs on the quantization of the multipliers embedded in the proposed filter architecture. This analysis paves the way to the design of multiplier-less decimation architectures. We also derive the impulse response of a sample 3rd order GCF filter used as a reference scheme throughout the paper.

Generalized Comb Decimation Filters for &lt;formula formulatype="inline"&gt;&lt;tex&gt;$\Sigma\Delta$&lt;/tex&gt;&lt;/formula&gt; A/D Converters: Analysis and Design

This paper addresses the design of generalized comb decimation filters, proposing some novel decimation schemes tailored to SigmaDelta modulators. We present a mathematical framework to optimize the proposed decimation filters in such a way as to increase the SigmaDelta quantization noise (QN) rejection around the so called folding bands, frequency intervals whose QN gets folded down to baseband because of the decimation process. Comparisons are given in terms of passband drop and selectivity with respect to classic comb filters with orders ranging from 3 to 6. As far as the practical implementation of the proposed filters is concerned, we present two different architectures, namely a recursive and a nonrecursive implementation, the latter of which constitutes the basis for realizing multiplier-less generalized comb filter (GCF) realizations. We propose a mathematical framework for evaluating the sensitivity of GCFs to the approximation of the multipliers embedded in the filter architectures. The considerations deduced from the sensitivity analysis, pave the way to an optimization algorithm useful for approximating the multipliers with power-of-2 coefficients