Showing papers on "Electronic filter published in 1995"

Synchronous frame based controller implementation for a hybrid series active filter system

Abstract: This paper proposes a synchronous reference frame based controller for a hybrid series active filter system. A hybrid series active filter system has been designed, built and installed at Beverly Pump Station in New England Electric utility for 765 kVA adjustable speed drive load to meet IEEE 519 recommended harmonic standards. The series active filter is rated 35 kVA-4% of the load kVA, and is controlled by a synchronous reference frame based controller to act as a harmonic isolator between the supply and load. This paper discusses the basic synchronous reference frame controller structure and addresses its operation under nonunity controller loop gain conditions. Design trade-offs and implementation issues of the synchronous reference frame controller are discussed. Operation of the hybrid series active filter system under off-tuned passive filter conditions and its impact on the performance of the synchronous reference frame based controller is experimentally evaluated. Effectiveness of the series active filter to provide harmonic damping and the use of simpler and low cost power factor correction capacitors as passive filters, is demonstrated by laboratory experimental results. Field installation and laboratory experimental results demonstrate the practical viability of the synchronous reference frame based controller for hybrid series active filter to provide harmonic isolation of nonlinear loads and to comply with IEEE 519 recommended harmonic standards.

Electromagnetic Compatibility in Power Electronics

Abstract: Introduction History of EMC standardisation efforts Description of electromagnetic disturbances Conducted EMI measurement EMI in power electronic equipment EMI filter elements Noise suppression EMI filter circuit selection and measurement EMI filter design Testing for susceptibility to power line disturbances Reduction techniques for internal EMI Transient susceptibility analysis method Bibliography Index

A new power line conditioner for harmonic compensation in power systems

Abstract: This paper proposes a new power line conditioner consisting of two small rating series active filters and a shunt passive filter. The power line conditioner aims at a general filtering system which will be installed at the point of common coupling in a power system feeding harmonic-sensitive loads and unidentified harmonic-producing loads. One of the two active filters is connected in series with the supply, while another is in series with the shunt passive filter. The purpose of the power line conditioner is to reduce voltage distortion at the connection point, and is to eliminate harmonic currents escaping into the system upstream of the connection point. A control scheme of the two series active filters which play an important role is described in this paper. Its filtering characteristics are discussed with the focus on voltage and current distortion. A prototype model of 20 kVA is constructed to verify the functionality and performance of the power line conditioner. >

Design and implementation of a hybrid series active filter system

Abstract: A hybrid series active filter system has been designed, built and installed at Beverly Pump Station in New England Electric Power Company utility for 765 kVA, 480 V adjustable speed drive load to comply with IEEE 519 recommended harmonic standards. The series active filter has a small rating-35 kVA which is 4% of the load kVA-and is controlled by a synchronous reference frame (SRF) based controller. The hybrid series active filter system is controlled to act as a "harmonic isolator" between the supply and load. This paper discusses the SRF controller implementation issues, design considerations of the series coupling transformer and protection issues of the small rating series active filter inverter. Operation of the series active filter under off-tuned passive filter conditions is investigated. The effectiveness of the series active filter to provide harmonic damping and the use of simpler and low cost passive filter structures such as power factor correction capacitors is demonstrated by laboratory experimental results. Field installation results demonstrate the practical and economic viability of hybrid series active filter systems for harmonic compensation of large nonlinear loads to comply with IEEE 519 recommended harmonic standards. >

Log-domain filters based on LC ladder synthesis

Abstract: A design method is proposed for the synthesis of linear, high-order, continuous-time filters using a unique translinear integrator circuit. Unlike previous attempts at incorporating translinear circuits into filter design, the proposed theory makes explicit use of the exponential nature of the bipolar transistor. This technique is based on the operational simulation of LC ladders. A 5th-order Chebyshev filter is designed, simulated and verified experimentally. The filter shows good amplitude response as well as distortion levels comparable to other filtering schemes.

Filtering of harmonic currents and damping of resonances in power systems with a hybrid-active filter

Abstract: A novel hybrid-active filter topology to minimize electric utility current harmonics at high power levels is presented in this paper. The proposed topology combines both passive and active filters to obtain the lowest power converter VA rating as compared to the power converter rating in the active filter and the series-active hybrid filter configurations. This is demonstrated with experimental results from a laboratory model. Transient and steady state operation of the hybrid-active filter is also presented. The control of the proposed filter is extended to provide damping of resonances due to neighboring loads. Simulation results showing the effect of active damping are presented. >

A new unified approach to power quality management

Abstract: A new control algorithm for a power converter-based device that is capable of alleviating the problems of harmonic interference and voltage regulation on radial distribution lines is introduced. It comprises a relocatable converter in series with a passive filter and is known as the Power Quality Manager. Simulation results based on an existing 88-kV line are presented. Experimental results are presented, based on a three-phase 200-VA scaled model of the existing 88-kV system. It is a cost-effective and flexible solution to improving power quality.

Utility interface issues for line connected PWM voltage source converters: a comparative study

Abstract: This paper examines the interface issues which occur when pulse width modulated (PWM) voltage source power converters (VSCs) are connected to the utility. In particular, it investigates the line current total harmonic distortion (THD) characteristics of various current regulated PWM (CRPWM) techniques with constraints on the power converter average switching frequency (power converter efficiency) and passive filter size (filter cost). Various CRPWM methods with proper filter and controller structures have been studied and evaluated by means of computer simulations for the utility interface with a variable speed wind turbine generating system. Dynamic performance has been evaluated as well as the steady state light load, full load, leading, lagging and unity power factor operating conditions. >

EMI line filter

Abstract: A filter circuit for reducing electromagnetic interference in an ungroundedhree-phase delta electrical system. The filter circuit includes a low- pass filter associated with each power phase having one input and output terminal placing an inductor in series with a phase conductor from a power supply. Input and output capacitors connect to a second input and output terminals respectively. An inductor connects in common between the second input and second output terminals thereby to complete a loop that is isolated from ground. Voltage suppression circuits connect from each phase to ground on the input side of the filter.

Quasi-Microwave Band Longitudinally Coupled Surface Acoustic Wave Resonator Filters Using ZnO/Sapphire Substrate

Abstract: The 1.5 and 2.4 GHz range 5IDT-type longitudinally coupled surface acoustic wave (SAW) resonator filters have been developed using ZnO/sapphire substrate. The 1.5 GHz range SAW filter has the minimum insertion loss of 1.0 dB and the relative bandwidth of 2.4% at the insertion loss of 3 dB. The 2.4 GHz range SAW filter has the minimum insertion loss of 1.7 dB and the relative bandwidth of 1.7% at the insertion loss of 3 dB. These filters are suitable for use as RF-stage filters in a personal digital cellular (PDC) system terminal and a wireless local area network (LAN) adapter, respectively.

Monolithic HBT active tuneable band-pass filter

Abstract: An active tuneable band-pass filter is provided which has a negative resistance circuit for generating a tuneable amount of negative resistance for a passive band-pass filter structure so as to compensate for resistive losses. The negative resistance circuit has a bipolar transistor with a base connected in shunt to the passive filter structure and a collector connected to a shunt inductive element. A negative resistance is generated at the base of the transistor and is applied to the passive filter structure. A coarse Q-factor tuning circuit is coupled to the emitter of the transistor for providing a coarse amount of tuning of the negative resistance. Also connected to the emitter terminal, is a fine tuning circuit for providing fine tuning of the negative resistance. The fine tuning may be achieved manually or automatically with a control circuit. The coarse and fine tuning capability provides a tuneable negative resistance which eliminates oscillations and compensates for resistive loss variations to realize improved q-factor.

Method of monitoring body movements using activity monitoring apparatus

Abstract: An activity monitor adapted to be worn on the non-dominant wrist of a subject includes a bimorphous beam motion sensor. The output signal of the sensor is amplified in an amplifier circuit having a selectable amplification factor, and filtered by highpass and lowpass filter circuits having individually selectable cut-off frequencies to obtain an analog signal for processing having a bandpass and amplitude characteristic corresponding to a particular body activity under observation. A control and processing circuit within the monitor includes a microprocessor which responds to either resident internal operating instructions or to externally supplied operating instructions, or to designated data signal parameters, to provide configuration control signals to the amplifier and filter circuits, and processing of the collected data, appropriate to the particular activity being monitored. The processed data is digitally stored in an internal memory for subsequent transfer through a data port to an associated computer for display or further processing.

Design methodology and experimental results for new ladder-type SAW resonator coupled filters

Abstract: Design methodology and experimental results for a new type of SAW filter called an "extended SAW resonator coupled filter" used in 800 MHz and 0.6 to 1.0 watt cellular radios are presented. The new filters have very small nonlinearities as well as high-performance and high-power characteristics. We have proposed a new equivalent circuit model for IDTs with leaky SAWs, which includes the propagation losses due to leakage and conductances caused by bulkwave radiation. Synthesis procedures for the new SAW filters based on the new treatments of leaky SAWs are discussed, and simulation and experimental results are also given. The new filters satisfy not only the required frequency-response specifications but also the spurious response sensitivity for an antenna duplexer used in USA cellular radio. >

Longitudinal leaky surface waves for high frequency SAW device applications

Abstract: Longitudinal leaky surface waves with a phase velocity of 6700 m/s and low propagation loss on lithium tetraborate (LBO) are reviewed. Moreover, the dispersion properties of longitudinal leaky surface waves propagating under the periodic Al strip grating on LBO are described theoretically and experimentally, for applications of the mode to the high frequency SAW devices. The theoretical method is based on Floquet's theorem using space harmonics as an orthogonal function set. It is found that the propagation loss at the lower edge of the first Bragg stopband for shorted gratings is relatively low. The parameters used in the electrical equivalent circuit model for designing the SAW filters, are obtained from the calculated dispersion curves. A 1.5 GHz SAW filter using the mode has been designed and fabricated for the filter of the global positioning system (GPS). A low loss SAW filter can be obtained easily without submicron fabrication techniques, by using the longitudinal leaky surface waves on LBO.

A new dynamic filter for the electronic ballast with the parallel-load resonant inverter

Abstract: This paper presents an efficient, small-sized, and cost-effective dynamic filter circuit for electronic ballasts with parallel-load resonant inverters. The proposed circuit performs the current shaping function by interposing resonant energy tanks between the bridge rectifier and the inverter stage. Theoretical and experimental results prove that almost unity power factor can be achieved by adding only few reactive components to the original circuit of the electronic ballast.

Surface acoustic wave filter with different filter portions satisfying complex conjugate relationship of impedances

Abstract: A SAW filter is configured so that a resonator-type filter portion, in which a plurality of SAW resonators are connected in series and in parallel, and a 3-electrode type serially coupled filter portion, in which three IDTs for inputting and outputting signals are interposed between reflectors, are serially connected on one and the same substrate. The design parameters of the respective SAW resonators are adjusted so that the impedances of respective sides of the filter portions, when viewed from the node of the resonator-type SAW filter portion and the 3-electrode type serially coupled SAW filter portion, substantially have a complex conjugate relationship with each other in the pass frequency band.

Compact television camera with switching noise prevention

Abstract: An object of the present invention is to provide a compact television camera having a circuit that prevents switching noises by that a transistor of a power supply circuit being switched on for a dc-dc converter only during a blanking period eliminates the need for a transformer and shielding box for the dc- dc converter circuit and a low-pass filter circuit, thereby allowing the camera body to be made smaller. The compact television camera circuit, comprises in combination, a synchronizing signal generator (1), a timing signal generator (2) for generating a timing signal from said synchronizing signal generator (1) output, a vertical driver (3) and a horizontal driver (4) for generating vertical and horizontal scanning signals using the timing signal, a CCD pick-up device (5), a low-pass filter (8) for eliminating the high-frequency components of a video signal (b) output of said CCD pick-up device (5), and an output amplifier (11) for feeding out the video output signal (a). The low-pass filter (8) is an active low-pass filter formed of an emitter follower amplifier having a unity gain of 1. The power supply circuit (20) is formed of a charging circuit of the double-voltage charging type, wherein a trigger signal (c) of the synchronizing signal generator (1) for triggering said power supply circuit (20) is a signal (c1) or (c2) having a rising edge and a falling edge during a blanking period BLK of the video signal (b).

Miniature low‐temperature high‐frequency filters for single electronics

Abstract: Single‐electron devices are now very promising for high‐accuracy and high‐sensitivity electrical measurements, based on the quantification of the macroscopic charge in metallic nanostructures The ultimate performance of these devices can only be attained by a careful filtering of the measurement circuit at very low temperature (20 mK) A new kind of wide‐band high‐frequency filter integrated on a copper block has been designed and studied This original substrate provides a massive and well‐thermalized electric ground plane in the vicinity of the filter Attenuation measurements show that one has to carefully design the filter box in order to avoid the transmission of electromagnetic modes through the filter box An improved filter showed −95 dB attenuation at 20 GHz, without any increase of the transmission at high frequency

Improvement in power durability of SAW filters

Abstract: This paper describes the improvement in power durability of SAW filters in terms of filter designs and electrode materials. In this study, we used the previously reported ladder-type filter composed of one-port SAW resonators. For filter design, short aperture length and reduction of resonant resistance improved power durability. We clarified the frequency dependence of chip temperature and lifetime in a ladder-type filter. For electrode materials, Cu sandwiched film has high power durability. This is caused by stone-wall-like structure and alloy formation in intermediate layers. The optimum Cu quantity for multi-layered film was significant for high power durability.

Switching circuit for a satellite broadcasting converter capable of assuring a high sensitivity

Abstract: There is provided a switching circuit of a BS converter capable of assuring a high sensitivity. A BS tuner superimposes a band switching pulse signal on a power voltage when selecting a high band, and supplies the resulting signal to a BS converter. The BS converter amplifies a pulse signal selected by a filter circuit of a switching circuit by ten times in a differential amplifier, rectifies the resulting signal in a rectifying circuit, and compares the resulting signal with a reference voltage in a comparator circuit, thereby detecting the presence or absence of the band switching pulse signal. When the band switching pulse signal is detected, a high-band local oscillator is turned on by a drive circuit. When the signal is not detected, a low-band local oscillator is turned on. Thus, by amplifying by about ten times the band switching pulse signal having a voltage of about 0.6 V, a reception frequency band is switchedly selected with high accuracy.

Synchronous tracking filter circuit for a broadcast satellite tuner

Abstract: A synchronous tracking filter circuit for use in a broadcast satellite tuner that comprises four varactors and a strip-shaped inductor plate or pcb-printed strip line which produces a resonant frequency. The circuit is used in a doubly tuned resonant circuit to incorporate the tracking with the frequency changes of a voltage controlled oscillator (VCO) synchronously. The circuit can also control the image interference. This type of design is applicable in the tuner of an indoor broadcast satellite receiver unit to act as the synchronous tracking filter of input frequencies.

Design and Evaluation of Li2B4O7 Surface Acoustic Wave Filter.

Abstract: A 250 MHz Li2B4O7 surface acoustic wave (SAW) filter was successfully designed using a newly developed program for double-mode SAW (DMS) filters. The elastic, piezoelectric and dielectric constants of Li2B4O7 grown by the resistance-furnace heating Czochralski method were measured precisely to determine the accurete phase velocity and the electromechanical coupling coefficient of SAW. The mode coupling coefficients were determined as a function of the electrode thickness as well. These coefficients were introduced in the simulation program, and the SAW filter was designed. The DMS filter fabricated in this study had almost the same characteristics as those expected from the design.

Filter circuit for pwm inverter

Abstract: PROBLEM TO BE SOLVED: To determine the constants of a reactor and a capacitor used for a filter only by the specifications of an inverter by decreasing the common-mode voltage of a carrier frequency component by a large extent, and decreasing the occurrence of loss caused by dumping. SOLUTION: A common-mode reactor 1 is inserted between a PWM inverter 11 and an AC motor driven by the inverter thereof. A three-phase star- connection reactor 3 is connected to the connecting point of the common-mode reactor 1 and the motor 12. A capacitor 2 grounds the neutral point of the reactor 3. These parts are provided. This is the filter circuit for the PWM inverter, wherein the resonant trequency by the common-mode reactor 1 and the capacitor 2 is located at the intermediate point between the output fundamental frequency of the inverter 11 and the carrier frequency and the inductance of the common-mode reactor 1 and the capacitance of the capacitor 2 are selected so as to be separated sufficiently from both frequencies.

Circuit especially for digital modulation apparatuses

Abstract: The circuit has a difference amplifier circuit (1), coupled to a filter circuit (3) via an output stage (2). The offset voltage for the filter circuit controls a regulating circuit (5, 6, 7) for providing an offset compensation signal (I, IX) for the output stage. Pref., the offset voltage and the offset compensation signal are provided as differential values, the offset voltage coupled to an amplifier (5), connected via a sample-and-hold stage (6) to the circuit (7) providing the offset compensation signal for the output stage.

Filter module for a frequency converter

Abstract: A filter module for a frequency converter comprises a filter circuit housed in a casing adapted for connection to the converter. The filter module includes an input filter and an output filter so arranged that input terminals for connection to the AC line voltage and output terminals for connection to an electric motor are disposed on a common side of the casing and so that the connections between the frequency converter and the filter module are disposed on a side of the casing which in use faces the converter.

Computer Simulations of Periodically Time-Varying Filters for Acoustic Feedback Control

Abstract: Several modern systems for reverberation enhancement use time-varying electronic filters to increase their gain before instability (GBI). A computer simulation study is presented of systems with linear periodically time-varying (LPTV) filters based on an iterative frequency-domain method. Results are given from simulations and measurements of a single feedback loop with phase and delay modulators and feedback via an electronic reverberation unit. Comparisons of measured and predicted values of GBI with a sinusoidal phase modulator showed deviations typically around 0.1 dB and at most 0.3 dB for modulation frequencies between 0.5 and 4 Hz and modulation indexes of up to 4.2 radians. Phase modulators displayed GBI improvements increasing almost monotonically with a modulation index up to 4.2 radians. Delay modulators gave slight improvements when used broad band, but when high-pass filtered at 600 Hz substantial improvements resulted with variations as low as ±0.5 ms. The detrimental effects of modulation in the form of audible amplitude and frequency fluctuations were studied as well.

Surface acoustc wave filter

Abstract: PURPOSE:To obtain the SAW filter having structure which increases an attenuation quantity nearly a passing band, specially, on a high frequency side more than in the passing band without deteriorating characteristics in the passing band. CONSTITUTION:The SAW filter is constituted by arranging plural IDTs 23-25 on a piezoelectric substrate 21 in the propagation direction of a surface wave. On the output side of the SAW filter, at least one one-port type SAW resonator 28 is connected in series and the antiresonance frequency fa of the above SAW resonator is set higher than the passing band of the SAW filter.

Distortion suppressor for digital-to-analog converter

Abstract: A circuit arrangement for suppressing spurious frequency components of an analog output of a digital-to-analog converter (DAC) features a track-and-reset sampling circuit coupled between the output of the DAC and a linearized differential buffer amplifier circuit including a filter circuit for minimizing high frequency distortion normally accompanying the output of a DAC operating at high frequencies, such as on the order of 500 MHz.