RLC Filter Research Articles

Simulation Implementation of Three Phase VSI Fed Three Phase Induction Motor Drive with Filter

Paper deals with an implementation of three phase induction motor fed from PWM voltage source inverter with RLC filter connected at the output of inverter. The analysis has been carried for under modulation range. The effect of modified modulation index on the rotor current, stator current, developed electromagnetic torque, line voltage and rotor speed of three phase induction motor is studied with the help of MATLAB/SIMLINK. The impact of the proposed approach on the transient and steady state response of the motor is included in the paper work. Paper also compares the total harmonic distortion in various parameters of inverter for different modulation index. Simulation is done on a three phase induction motor fed by a PWM voltage source inverter with filter which is developed in MATLAB/SIMULINK environment. There is appreciable improvement in THD of inverter line, phase voltage and current with increase in modulation index. The modified modulation method leads to the improvement in motor performance.

Robust Digital Filter Structures: A Direct Approach

One of the many contributions of Prof. Fettweis was the invention of wave digital filters. These filters are obtained from classical RLC filters, in particular doubly terminated lossless two-ports, by using some transformations. Namely, the voltages and currents in the circuit elements are transformed into wave-variables and then a bilinear transformation is performed. If the wave transformation is performed appropriately it results in a realizable digital filter structure which furthermore enjoys a number of robustness properties such as low passband sensitivity, low roundoff noise, and freedom from limit cycle oscillations. Prof. Fettweis and his colleagues also showed that these properties are due to the inheritence of passivity properties from the continuous-time domain into the digital filter domain. Subsequent to this landmark work, a number of researchers worked on the problem of obtaining robust digital filter structures without starting from continuoustime circuits. One of these is the structurally bounded or structurally passive class of digital filters. These structures are based on inducing structural passivity directly into the implementation and are therefore simpler, both conceptually and from a practical viewpoint. They are also more general and lead to new structures which have no natural connection to electrical circuits. This paper gives an overview of some of these developments.

Suppression of Weakly-Damped Torsional Oscillations in Autonomous Power Systems

Variants are considered for suppression of weakly-damped vibration effects caused by the first critical frequency of torsional oscillations of a gas-turbine unit in the autonomous electric power system of an oil and gas field. It is shown that torsional oscillations can be suppressed with the aid both of a reactive power source installed at the field power system, consisting of a controlled shunt reactor (CSR) and a static capacitor battery, and of an auxiliary active RLC filter, when using in both cases auxiliary control loops of torsional deviation as well as its first and second derivatives. A methodology has been developed for simultaneous coordination of the settings of any regulation system based on a numerical optimization, which permits selecting the characteristics of control loops of the source of reactive power and active RLC filter that are optimal from the point of view of suppressing torsional oscillations.

Lossy/Lossless Grounded Inductance Simulators Using Current Feedback Operational Amplifier (CFOA)

Active elements are critical in implementing active filters, oscillators, rectifiers, and signal processing circuits. We observe that several active circuits have been proposed in the literature. In this study, we have proposed four inductance simulators that employ only one active circuit current feedback operational amplifier and three or four passive components. The first and fourth topologies are designed for series lossy inductance, whereas the second and third topologies are designed for lossless negative inductance simulators. A passive RLC filter is used to demonstrate the effectiveness of the proposed inductance simulators. The simulations performed with the LTSpice program and the results agree with the theoretical analysis.

Filter design at the output of the inverter in PMSM drives

PurposeThis paper aims to describe a simple low-pass filter to suppress torque pulsation and current harmonics in permanent magnet synchronous motor (PMSM) drives.Design/methodology/approachFor the control of the PMSM, a field-oriented control algorithm is always used. The proposed filter is actually a resistance, inductance, capacitance (RLC) filter. At the output of the inverter and the input of PMSM, an RLC filter is connected. This filter suppresses current harmonics through filtering phase voltage harmonics. Analysis of the filter is achieved through frequency characteristics analysis.FindingsThis filter can effectively filter out the harmonic of phase voltage. Both the simulation and experiment results show that the proposed filter can effectively suppress torque pulsation and current harmonics in PMSM drives. Also, the method of selecting filter parameters and the whole control system are very simple.Research limitations implicationsThe filter increases the design cost of the system.Practical implicationsThe harmonics and torque ripple of phase current are greatly suppressed. Also, the loss of the PMSM reduced.Originality/valueThe method of selecting filter parameters and the analysis of the proposed filter are proposed for the first time.

An improved Dynamic Voltage Restorer for power quality improvement

The capacity of the voltage source inverter (VSI) and the values for the link filter connected between the injection transformer and the inverter play a crucial in the design of the DVR. In this research paper, new Dynamic Voltage Restorer (DVR) topology has been proposed. The capacity of the voltage source inverter (VSI) and values of the link filter is small that will improve the compensation capabilities for voltage harmonic, swell and voltage sag mitigation under various fault conditions. The new RLC filter is able to eliminate the switching harmonics. The capacity of the dc supply voltage is reduced when the value of inductance is small. The new DVR topology has high efficiency and the ability to improve the quality of voltage. An outline architecture of the RLC filter parameters for the specific model has been presented. The new DVR topology is modeled and simulated using the PSCAD/EMTDC. The control scheme has good control dynamics with minimum transient current overshoot. The simulation results under transient performance are good.

Power System Harmonic Elimination to Improve Power Quality

An improvised RLC interface filter for a Dynamic Voltage Restorer (DVR) is proposed. The RLC filter is connected in the front end between the IGBT based Voltage Source Inverter (VSI) and the injection transformer and is able to eliminate voltage harmonics in the system and also switching harmonics generated from VSI. The voltage at the sensitive load end is pure sinusoidal. In this method, the DVR produced Pulse Width Modulation (PWM) voltage with voltage harmonic canceling the voltage harmonic generated from the supply main. The VSI handles harmonic power. The low order switching harmonics generated by the IGBT based VSI is suppressed. The DVR has greater voltage injection capability. Good dynamic and transient results recorded and Total Harmonic Distortion (THD) at the sensitive load end is minimized. The voltage at the sensitive load is sinusoidal and at 1.0 pu. PSCAD/EMTDC is used to validate the performance of the interface filter and the DVR. Simulated results are presented.

A Low-Loss “RL-Plus-C” Filter for Overvoltage Suppression in Inverter-Fed Drive System With Long Motor Cable

Inverter-fed drive systems have been widely used in residential, commercial, and industrial applications. Special emphasis is placed on avoiding overvoltage spikes traveling along the cable and inside the motor, when a long motor cable is used. Such phenomenon would cause premature failure of the motor and cable insulation. Many passive and active overvoltage suppression techniques have been proposed to tackle this issue. Among them, passive overvoltage filters are dominant solutions, as their implementation is simple, cost effective, and robust. However, they have the main drawback of high power dissipation. This paper gives a new perspective on this subject. A generalized model for characterizing the inverter-cable-motor system with the filter included will be formulated to describe the interactions between the filter and the drive system. Then, the characteristics of an ideal overvoltage filter will be derived. Furthermore, a low-loss filter, named as “RL-plus-C” filter that exhibits near ideal characteristics will be proposed. Its performance will be compared with that of the commonly adopted RC and RLC filters, theoretically and experimentally on a 1-hp motor drive system. Results reveal that the proposed filter has the lowest power dissipation.

Voltage harmonic elimination with RLC based interface smoothing filter

A method is proposed for designing a Dynamic Voltage Restorer (DVR) with RLC interface smoothing filter. The RLC filter connected between the IGBT based Voltage Source Inverter (VSI) is attempted to eliminate voltage harmonics in the busbar voltage and switching harmonics from VSI by producing a PWM controlled harmonic voltage. In this method, the DVR or series active filter produces PWM voltage that cancels the existing harmonic voltage due to any harmonic voltage source. The proposed method is valid for any distorted busbar voltage. The operating VSI handles no active power but only harmonic power. The DVR is able to suppress the lower order switching harmonics generated by the IGBT based VSI. Good dynamic and transient results obtained. The Total Harmonic Distortion (THD) is minimized to zero at the sensitive load end. Digital simulations are carried out using PSCAD/EMTDC to validate the performance of RLC filter. Simulated results are presented.

A New Optical Gain Model for Quantum Wells Based on Quantum Well Transmission Line Modeling Method

This paper presents a new method for modeling the gain spectrum in quantum well (QW) structures based on the QW transmission line modeling (QW-TLM) method. In the QW-TLM method, three parallel RLC filters together with their associated weight coefficients constitute a QW-TLM unit, which represents the processes that electrons transit from the conduction band to the heavy hole band, the light hole band, and the spin-orbit split-off band at a specific wave vector. Parallel QW-TLM units are adopted to describe the electron transitions in the wave vector space. Furthermore, the optical gain model of QWs based on the QW-TLM method is presented. The gain spectrum obtained through the QW-TLM method is agreeable with the gain spectrum calculated from the analytical expression in a large wavelength range from 1300 to 1700 nm. In order to reduce the computation time, under sampling QW-TLM is proposed to model the gain curve of QWs. The simulation result shows that the gain curve obtained from under sampling QW-TLM is consistent with the gain curve obtained through the theoretical derivation from 1510 to 1575 nm, which satisfies the requirement of studying the dynamic spectral characteristics of QW devices.

High‐frequency reverse‐time chaos generation using digital chaotic maps

Reverse-time chaos can be used to realise hardware chaotic systems that can operate at speeds equivalent to existing state-of-the-art while requiring significantly less complex circuitry. Unlike traditional chaotic systems, which require significant analogue hardware that is difficult to realise at high speed, the reverse-time system can be realised with a field programmable gate array calculating a digital iterated map. The resulting output forgoes the need for digital-to-analogue conversion by directly driving a series RLC filter. Since the dynamics of this system are determined by an iterated map, precise control of this system is possible by adjusting the map's initial condition. Hardware results for the controllable reverse-time system demonstrate chaotic behaviour at an operating frequency of 1.8 MHz and show promise for extension to higher frequencies.

Implementing a simple vectorial bridge with a digital oscilloscope

We show how to exploit instrumentation available in undergraduate student laboratories to build a simple vectorial bridge. In particular, we take advantage of the ability to read data from a digital oscilloscope with a personal computer and describe an algorithm to obtain an accurate evaluation of the phase difference between two sinusoidal signals. The use of the bridge to characterize components of a high-Q RLC filter is shown to greatly improve the understanding of results in electrical resonance experiments. Direct evidence of dielectric losses, skin currents, and the effect of distributed capacitance is obtained.

Control Management Strategy of Stand-Alone Hybrid Power Micro-System Using Super-Capacitor

This paper concerns the power management of an isolated hybrid micro-system for residential electricity supply, comprising a variable speed wind turbine (VSWT) and a photovoltaic (PV) panel as principal sources. A super-capacitor (SC) bank is considered as a storage system. These sources are connected to a three-phase load via a unidirectional inverter and an RLC filter. Taking into account the fluctuating nature of renewable sources and the variation of the required power, a diesel engine which is considered as a backup source and a dump load which is regarded as an auxiliary load, are connected on the AC side to ensure balance between the generated and the requested powers. In fact, a control strategy is developed to manage the power flows between the hybrid system devices and to make decision to choose the optimal operating mode ensuring the continuous supply of the load and maintaining the SC state of charge (SOC) at acceptable levels. Simulation results are presented to show the effectiveness of the proposed control system under six operating modes.

Use of Synchronous Modulation to Recover Energy Gained From Matching Long Cable in Inverter-Fed Motor Drives

As inverter-fed motor drives generate fast-switching voltage pulses, the transmission-line effects on long motor cable and motor stator windings lead to overvoltage on the cable and motor terminals, as well as inside motor stator windings, and also an increase in the common-mode current. Such phenomenon would cause premature failure of motor and cable insulation. A general protective measure is the use of a passive filter, such as RC and RLC filter, to reduce the voltage surges by matching the cable impedance and/or altering the rise time of the voltage pulses. However, passive filters are bulky and lossy. This paper presents an active motor terminal filter with energy recovery function that can achieve the same functions as the passive filters, but consumes much less power. The proposed filter recovers energy gained from suppressing motor terminal voltage surges and regenerating the recovered energy back to the whole system. An experimental filter has been built and evaluated on a 1-hp three-phase motor drive system. A comparative study into the performance among commonly used RC filter and RLC filter and the proposed filter will be given.

Implementing Boundary Conditions in Simulations of Arterial Flows

Computational hemodynamic models of the cardiovascular system are often limited to finite segments of the system and therefore need well-controlled inlet and outlet boundary conditions. Classical boundary conditions are measured total pressure or flow rate imposed at the inlet and impedances of RLR, RLC, or LR filters at the outlet. We present a new approach based on an unidirectional propagative approach (UPA) to model the inlet/outlet boundary conditions on the axisymmetric Navier-Stokes equations. This condition is equivalent to a nonreflecting boundary condition in a fluid-structure interaction model of an axisymmetric artery. First we compare the UPA to the best impedance filter (RLC). Second, we apply this approach to a physiological situation, i.e., the presence of a stented segment into a coronary artery. In that case a reflection index is defined which quantifies the amount of pressure waves reflected upon the singularity.

Optimization of Fractional-Order RLC Filters

This paper introduces some generalized fundamentals for fractional-order RLβCα circuits as well as a gradient-based optimization technique in the frequency domain. One of the main advantages of the fractional-order design is that it increases the flexibility and degrees of freedom by means of the fractional parameters, which provide new fundamentals and can be used for better interpretation or best fit matching with experimental results. An analysis of the real and imaginary components, the magnitude and phase responses, and the sensitivity must be performed to obtain an optimal design. Also new fundamentals, which do not exist in conventional RLC circuits, are introduced. Using the gradient-based optimization technique with the extra degrees of freedom, several inverse problems in filter design are introduced. The concepts introduced in this paper have been verified by analytical, numerical, and PSpice simulations with different examples, showing a perfect matching.

Mitigation of Voltage flicker and reduction in THD by using STATCOM

Voltage flicker is considered as one of the most severe power quality problems (especially in loads like electrical arc furnaces) and much attention has been paid to it lately. Due to the latest achievements in the semiconductors industry and consequently the emergence of the compensators based on voltage source converters, FACTS devices have been gradually noticed to be used for voltage flicker compensation. This paper covers the contrasting approaches; dealing with the voltage flicker mitigation in three stages and reduction in total harmonic distortion and assessing the related results in details. Initially, the voltage flicker mitigation, using FCTCR (Fixed Capacitor Thyristor Controlled Reactor), was simulated. Secondly, the compensation for the six-pulse as well as 12-pulse Static Synchronous Compensator (STATCOM) has been performed. In this case, injection of harmonics into the system caused some problems which were later overcome by using 12-pulse assignment of SATCOM and RLC filter (three phase harmonic filter). The obtained results show that STATCOM is very efficient and effective for the flicker compensation as well as harmonic sprectrum. All the simulations have been performed on the MATLAB Software. DOI: http://dx.doi.org/10.11591/ijece.v3i1.1951

Compensation of Voltage Flicker by Using Facts Devices

Voltage flicker occurs when heavy loads are periodically turned on and off in a weak distribution system. If the distribution system’s short circuit capacity is not large enough, voltage fluctuations will occur. Voltage flickering can be extremely harmful to sensitive electronic equipment. Computerized equipment requires stable voltage to perform properly. This paper covers the contrasting approaches; dealing with the voltage flicker mitigation in three stages and assessing the related results in details. Initially, the voltage flicker mitigation, using FCTCR (Fixed Capacitor Thyristor Controlled Reactor), was simulated. Secondly, the compensation for the Static Synchronous Compensator (STATCOM) has been performed. In this case, injection of harmonics into the system caused some problems which were later overcome by using 12-pulse assignment of SATCOM and RLC filters. The obtained results show that STATCOM is very efficient and effective for the flicker compensation. All the simulations have been performed on the MATLAB Software

An Active Low-Loss Motor Terminal Filter for Overvoltage Suppression and Common-Mode Current Reduction

Inverter-fed motor drive systems are widely used in industrial applications because of their energy efficiency and flexible control of machinery using maintenance-free induction motors. As switching inverters generate fast-switching voltage pulses, the transmission-line effects of the motor cable and motor stator windings become significant, and may lead to a doubling of the supply voltage to the motor and cable, overvoltage inside the motor windings, and an increase in the common-mode current. Such phenomena cause premature failure of the motor and cable insulation. A typical protective measure is the use of a passive filter to reduce the voltage surges and alter the rise time of the voltage pulses at the motor terminals. However, most passive filters have the drawbacks of bulky size and high power loss. This paper presents an active terminal filter that can perform the same functions as the passive filters with low power dissipation. An experimental filter has been built and evaluated on a 1-hp three-phase motor drive system with different motor cable lengths. A comparative study into the performance among the commonly used RLC filter and RC filter, and the proposed filter is provided.

Memristive diode bridge with LCR filter

The class of nonlinear dynamical systems known as memristive systems was defined by Chua and Kang back in 1976. Since then, many studies have addressed the search for physically-realisable memristive systems. In this reported work, it is proved that the class of memristive systems encloses an elementary electronic circuit comprising a full-wave rectifier with a second-order RLC filter.