Voltage-controlled filter

About: Voltage-controlled filter is a research topic. Over the lifetime, 5514 publications have been published within this topic receiving 70872 citations. The topic is also known as: VCF.

A Si 1.8 GHz RLC filter with tunable center frequency and quality factor

Abstract: A second-order active bandpass filter using integrated inductors was implemented in Si bipolar technology. The filter uses special techniques to make the quality factor and the center frequency tunable. For a nominal center frequency of 1.8 GHz and a quality factor of 35, the filter has 1 dB compression dynamic range of 40 dB, and draws 8.7 mA from a 2.8 V supply.

A tunable filter and method of tuning a filter

Abstract: A bandpass filter is tuned by converting the filter into an oscillator using a negative resistance circuit, tuning the oscillator by using conventional tuning techniques such as tuning a varactor via a phase locked loop, sampling and holding the tuning signal and switching off the negative resistance circuit to convert the oscillator back into a bandpass filter.

A Novel Design and Optimization Method of an $LCL$ Filter for a Shunt Active Power Filter

Abstract: Compared with the L filter, the LCL filter is more suitable for high-power low-switching-frequency applications due to its better attenuation characteristics on high frequencies. However, the parameter design for the LCL filter is more complex since both the inhibiting effect of the high-frequency harmonic current and the influence to the controller response performance of the converter should be considered. In this paper, the model of the LCL filter and the design criteria of the LCL filter for a shunt active power filter (SAPF) are analyzed in the beginning. Then, the impacts of all parameters of the LCL filter on SAPF are intuitively drawn on a graph by theoretical derivation. Finally, a novel parameter design and optimization method for the LCL filter is proposed. The validity and effectiveness of the proposed method are proved by simulated and experimental results of a single-phase SAPF prototype at the end of this paper.

A hybrid active filter for damping of harmonic resonance in industrial power systems

Abstract: This paper proposes a hybrid active filter for the damping of harmonic resonance in industrial power systems. The hybrid filter consists of a small-rated active filter and a 5th-tuned passive filter. The active filter is characterized by detecting the 5th-harmonic current flowing into the passive filter. It is controlled in such a way as to behave as a negative or positive resistor by adjusting a feedback gain from a negative to positive value, and vice versa. The negative resistor presented by the active filter cancels a positive resistor inherent in the passive filter, so that the hybrid filter acts as an ideal passive filter with infinite quality factor. This significantly improves damping the harmonic resonance, compared with the passive filter used alone. Moreover, the active filter acts as a positive resistor to prevent an excessive harmonic current from flowing into the passive filter. Experimental results obtained from a 20-kW laboratory model verify the viability and effectiveness of the hybrid active filter proposed in this paper.

A Novel Inverter-Output Passive Filter for Reducing Both Differential- and Common-Mode $dv/dt$ at the Motor Terminals in PWM Drive Systems

Abstract: A novel inverter-output filter, which cannot only filter the differential-mode voltage dv/dt but also suppress the common-mode voltage dv/dt and their rms values, is proposed in this paper. The filter is in combination with a conventional RLC filter and a common-mode transformer. The main advantage is that the functions of filtering a differential-mode voltage and suppressing a common-mode voltage can be integrated into a single system. Furthermore, the structure and design of the proposed filter are rather simple because only passive components are used. Simulations and experiments are conducted to validate the performance of the proposed filter. Both of their results indicate that about 80% of the rms value of the common-mode voltage are suppressed, while the demand of differential-mode voltage filtering is still met