Analysis and evaluation of different modulation techniques for active power filters

Abstract

The efectiveness of an active power filter depends basically on three characteristics: a) the design characteristics of the PWM modulator, b) the method implemented to generate the reference template and c) the modulation method used. For the last characteristic there are many methods, most of them based on PWM strategies. In this paper, three of these methods, whose characteristics are their simplicity, are analyzed: Periodical Sampling Control, Hysteresis Band Control, and Triangular Carrier Control. These three methods have been tested with different waveform templates: sinusoidal, quasisquare and rectifier compensation current. The paper shows that, depending on the type of current the active filter has to follow, one strategy may be better than the others. The analysis is based on using the same switching frequency and the results are compared through a THD method which takes into account the particular shape of the waveform template. Simulations and experimental results are presented in the paper.

Improved constant-frequency hysteresis current control of VSI inverters with simple feedforward bandwidth prediction

“…The proposed control was extensively simulated to test its effectiveness and to evaluate the improvements with respect to the original constant-frequency hysteresis method [11], [22] and other current control methods [1]- [5]. The simulation was also employed for the choice of suitable parameters for the PLL and the band estimator, in order to optimize the response, while ensuring stability and robustness.…”

“…12, the classic limitations of the ramp-comparison control are evident [1]- [5], [23]. Although the integral action keeps the average value of the output signal at zero, the proportional gain must be limited to ensure stability in the presence of current ripple.…”

“…YSTERESIS current control of voltage-source inverters (VSI's) offers an unsurpassed transient response in comparison with other analog and digital techniques, which makes it advisable to adopt this method in all cases where high accuracy, wide bandwidth, and robustness are required [1]- [5].…”

Investigation of the Influence of the Transformer of a Series Active Filter on the Quality of Voltage

“…У результаті відбувається взаємна компенсація неосно-вних гармонік напруги навантаження і зазначених напівпровідникових перетворювачів. Попередні до-слідження компенсаційних властивостей активного фільтра залежать від алгоритма визначення заданого сигнала управління [4]. Тому з розвитком науки та техніки активно вдосконалюються не тільки апаратна частина компенсатора але і його алгоритмічні засоби.…”

Comparison of current control techniques for active filter applications

“…Each of these have undergone a substantial evolutionary process, due their diffused industrial applications, so that the actually employed techniques indeed feature a large number of refinements with respect to the originally introduced versions. This paper is aimed at both summarizing the main implementation refinements which characterize the latest versions of the aforementioned control techniques and comparing the different performance [5], [6] achieved by the three current controls in a typical active filter applicative situation, considering the state-of-the art implementation of each one, so as to achieve simulated results which are as realistic as possible.…”