Showing papers on "Electronic filter published in 2012"

Generalized Closed-Loop Control Schemes with Embedded Virtual Impedances for Voltage Source Converters with LC or LCL Filters

Abstract: In this paper, a generalized closed-loop control (GCC) scheme is proposed for voltage source converters (VSCs) with LC or LCL output filters. The proposed GCC scheme has a single-loop control of inverter output (voltage or current) and two parallel virtual impedance terms using additional measurements. The virtual impedance can be the equivalent internal impedance or external impedance (or both), depending on their control term and feedback variable selection. The internal impedance term is mainly responsible for providing desired damping to the filter circuit, and the external virtual impedance term can effectively adjust the converter system closed-loop output impedance. As each term in the GCC scheme can be controlled independently, the proposed GCC scheme has great flexibility and can easily realize and explain the performances of the traditional single- and multiloop control schemes and their different variations. Moreover, the GCC scheme provides a distinct physical meaning of each control term, which makes the control parameter tuning more straightforward and robust. Additionally, as shown in this paper, the proposed GCC scheme can tackle some traditionally challenging control objectives by avoiding the harmonics filtering or derivative terms. Experimental results from laboratory VSC prototypes are obtained to validate the proposed GCC scheme.

A Lyapunov-Function-Based Control for a Three-Phase Shunt Hybrid Active Filter

Abstract: In this paper, an energy-based Lyapunov function control technique is developed for a three-phase shunt hybrid active filter (SH-AF) to compensate harmonics generated by nonlinear loads and is applied for balanced operation. The method provides compensation for harmonic load current components. The strategy determines the control law that makes the derivative of the Lyapunov function always negative for all values of the states. The dc bus voltage of the SH-AF is maintained to 50 V, which is significantly lower than that of the conventional hybrid active filter. The rating of the active filter in the SH-AF system is much smaller than the one used in the conventional shunt active power filter because the passive filter takes care of the major burden of compensation. The SH-AF performances, during both nominal and severe operating conditions, are then evaluated using a dSPACE DS1104 controller board, supported by a Matlab/Simulink Real-Time Workshop environment. A significantly high correlation between the experimental results and the theoretical model, implemented with Simulink/Matlab, is obtained.

A Hybrid Active Filter for a Three-Phase 12-Pulse Diode Rectifier Used as the Front End of a Medium-Voltage Motor Drive

Abstract: This paper describes a hybrid active filter intended for mitigating the line-side harmonic currents of a three-phase 12-pulse diode rectifier used as the front end of a medium-voltage high-power motor drive. This hybrid filter is characterized by series connection of a simple LC filter and a small-rated active filter. This circuit configuration brings low cost, small size, and light weight to the hybrid filter. A three-phase experimental system rated at 400 V and 15 kW is designed, constructed, and tested, which is a downscaled model of the medium-voltage motor drive system. In this experiment, the LC filter is tuned to the 11th-harmonic frequency, and the active filter is based on a three-level neutral-point-clamped pulsewidth modulation converter (NPC PWM) with a dc capacitor voltage as low as 28 V. This hybrid filter is connected on either first or fourth winding of a line-frequency transformer with a first Δ-winding voltage of 400 V in the primary, and a second Δ-winding voltage of 220 V, a third Y-winding voltage of 220 V, and a fourth Δ-winding voltage of 400 V in the secondary. Experimental results show that the hybrid filter performs satisfactory filtering in a range from no-load to full-load conditions.

Parallel-Connected Shunt Hybrid Active Power Filters Operating at Different Switching Frequencies for Improved Performance

Abstract: This paper proposes a combination of low- and high-frequency hybrid active power filter (APF) to operate in parallel for better performance. The individual hybrid APF is a series combination of L-C filter with the corresponding voltage source inverter. The dc links of both the inverters are connected in parallel, and the voltage of the dc link is maintained by the low-frequency inverter (LFI). The low- and high-frequency inverters eliminate lower order and higher order harmonics, respectively. In addition, it is possible to design the LFI such that it can also compensate the reactive power of the load. The individual L-C filter of the hybrid topology is designed to take care of specific order of harmonics that are predominant in the load. A combination of feedforward and feedback controller is designed for the proposed conditioner. The performances of the proposed topology and the controller are first examined by MATLAB/SIMULINK-based simulation. An experimental prototype is also designed to confirm the usefulness of the proposed system.

Optimal $C$ -Type Passive Filter Based on Minimization of the Voltage Harmonic Distortion for Nonlinear Loads

Abstract: In its broadest sense, passive filters have been a very potent technique for power system harmonic suppression because of their possible different frequency response characteristics that can achieve a certain required harmonic filtering target, also due to their simplicity and economical cost. This paper presents an application of FORTRAN feasible sequential quadratic programming to find the optimal sizing of parameters of C-type passive filters for minimizing the total voltage harmonic distortion of nonlinear loads, where maintaining a given power factor at a specified range is desired. The optimal design of the C-type passive filter as an alternative to the conventional passive filtering techniques is introduced, and a detailed comparison of the results between an uncompensated system and a C-type filter are discussed by means of different numerical examples, considering source and load nonlinearities, while taking into account compliance with the IEEE standards 519-1992 and 18-2002.

Wide-Loading-Range Fully Integrated LDR With a Power-Supply Ripple Injection Filter

Abstract: A low-dropout regulator for on-chip application with a power-supply rejection (PSR) boosting filter circuit for enhancing supply noise rejection at middle-to-high frequency over a wide loading range is presented in this brief. The idea has been analytically modeled and experimentally verified with a standard 0.13- μm CMOS process. The on-chip compensation capacitance is 1 pF. For the PSR filter design, the total on-chip capacitance is 20 pF. From the experimental results, the implemented regulator can operate with supply voltage of 1.2 V with nominal dropout voltage of 0.2 V at maximum load of 50 mA and IQ of 37.32 μA.

Strictly passive FIR filtering for state-space models with external disturbance

Abstract: This paper proposes a new strictly passive filter with a finite impulse response (FIR) structure for linear state-space signal models with external disturbance. This filter is called a strictly passive FIR filter (SPFF). We apply the strict passivity concept to derive a new linear filter with FIR structure and quasi-deadbeat property. The gain matrix of the proposed SPFF in this paper can be determined by resorting to the solution to a linear matrix inequality (LMI) feasibility problem. An illustrative example is presented to show the validity of the SPFF.

Controlling Conducted Emissions by Design

Abstract: I. Fundamentals of Conducted Emission Design.- 1. Designing for EMC.- 1.1 Noise (EMI).- 1.2 EMI Source, Path, and Victim.- 1.3 Conductive Paths.- 1.4 Conduction or Radiation?.- 1.5 Design to Control Conducted Emissions.- 2. EMI Spectrum.- 2.1 Time and Frequency Domains.- 2.2 Description of FFT Software.- 2.3 Data Interpretation.- 2.4 Bare Bones FFT.- 2.5 Methods of Inputting Data to FFT.- 2.6 An Enhanced Version of FFT.- 2.7 Examples of FFT Conversions from Time to Frequency Domains.- 2.8 Some Possible Pitfalls.- 2.9 Subharmonics.- 3. Capacitor Modeling.- 3.1 The Capacitor Model.- 3.2 Parasitic Elements of Capacitors.- 3.3 Capacitor Types.- 3.4 Capacitor Voltage Ratings.- 4. Inductor Modeling.- 4.1 Inductor Losses.- 4.2 Inductor Capacitance.- 4.3 Air Core with Conductor Near Experiment.- 4.4 Inductor Cores Form Capacitive Paths.- 4.5 Inductor Impedance Curve.- 4.6 Parasitic Elements of Inductors.- 4.7 Simulation.- 5. Balun Modeling.- 5.1 Differential Mode Flux.- 5.2 Common Mode Flux.- 5.3 The Truth about Windings on Inductor Cores.- 5.4 Coupling K Factor.- 5.5 Differential Balun Inductance.- 5.6 Common Mode Balun Inductance.- 5.7 Effects of Load and Source Resistances on Attenuation.- 5.8 Balun Driving Impedance.- 5.9 Balanced Circuits.- 5.10 Design Criteria.- 5.11 Model.- 6. Filters.- 6.1 Parasitic Inductances and Capacitances.- 6.2 Academic LC Filter.- 6.3 Simple Real World LC Filter.- 6.4 Control Parasitics by Design.- 6.5 Parasitics Caused by Circuit Layout.- 6.6 Filter Circuit Design.- 6.7 Characteristic Impedance of LC Filters.- 6.8 Parallel Capacitors to Lower the ESR.- 6.9 LC Filter.- 6.10 Line Impedance Stabilization Networks.- 6.11 Filter Layout and Packaging Design.- 7. Grounding Electronic Circuits.- 7.1 Grounding.- 7.2 Safety Grounds.- 7.3 Ground Geometries.- 7.4 Ground Design for Packaging ElectronicCircuitry.- 7.5 Shielding.- 8. EMI Analysis.- 8.1 EMI Modeling.- 8.2 EMI Analysis Using SPICE.- II. Advanced Conducted Emission Design.- 9. EMC Regulations.- 9.1 FCC.- 9.2 VDE.- 9.3 MIL-STD-461.- 9.4 Voltage/LISN Measurement Method.- 9.5 Current/Capacitor Measurement Method.- 9.6 A Comparison of Some of the RF Conducted Emissions Standards.- 10. Switch Mode Power Supplies.- 10.1 Typical Power Supply Block Diagram.- 10.2 Typical Switch Mode Power Supply EMI Problem Areas.- 10.3 EMI Simulation and Laboratory EMI Test Setup.- 10.4 SMPS EMI Design Example.- 10.5 Model the Problem.- 10.6 Simulation Problems.- 10.7 Back to Fundamental Model.- 10.8 Identify the Players.- 10.9 Other Types of EMI Modeling for SMPS.- 10.10 Conclusion.- 11. Transistor and Diode Packaging Problem for EMI.- 11.1 New Semiconductor Device Packages.- 11.2 Common Mode Shorting Screens.- 11.3 Typical System with Power Conversion.- 11.4 Common Mode Current Paths.- 11.5 Conducted Emissions Reduction by Choice of Package.- 12. Circuit Examples.- 12.1 Example 1.- 12.2 Example 2.- 12.3 Example 3 (FFT).- 13. Computers and Digital Logic Circuitry.- 13.1 Conducted Emissions Coupling Paths.- 13.2 Sequential Logic and Clocks.- 13.3 Example of Internal Conducted Emissions.- 13.4 What Is the Best Bypass Capacitor?.- 13.5 Power Entry Capacitor.- 14. What This Analysis Method Is Not.- 14.1 Diagnostics.- 14.2 Fields.- 14.3 Radiation.- 14.4 Characteristic Impedances of Common Pairs of Conductors.- 14.5 Shortcomings of EMI Test Simulation as Described Herein.- 15. Magnetic Saturation Modeling.- 15.1 The Polarization of Magnetic Domains.- 15.2 Device, Core, and Material Properties.- 15.3 Core Geometry Effects.- 15.4 Effects of Cores Made of Two Different Materials.- 15.5 Some Crucial Parameters to Model Saturation.- 15.6 Methods of Integrating Voltage.- 15.7 Dr. Lauritzen's Saturation Model.- 15.8 The Core Geometry and Material Porosity Region of the B-H Loop.- 15.9 Curve Fitting versus Parametric Models.- 15.10 Conclusion.- Appendix. BASIC FFT.

Analysis and design of different control strategies of hybrid active power filter based on the state model

Abstract: A configuration consisting of a combination of a series active power filter (APF) and a parallel passive filter is shown to be an efficient system for non-linear load compensation For this topology, different compensation strategies are proposed to control the series APF The most effective strategies determine the APF compensation voltage in proportion to the source current harmonics The proportionality constant ` k ' in the control algorithm implementation is related to the APF gain and complete system dynamic In this study, the system state model is obtained for three control strategies of series APF: compensation voltage proportional to source current harmonics, compensation voltage opposite to the load voltage harmonics and a hybrid strategy which combines both previous strategies The analyses of the resulting models provide the information needed to establish design criteria with respect to harmonic filtering and system stability The methodology proposed in this study eliminates the arbitrary choice of the proportionality constant The three strategies were analysed in two different situations: sinusoidal supply voltages and distorted supply voltages Finally, results of an experimental prototype developed for this purpose allowed the proposed analysis to be verified

Voltage sampling circuit

Abstract: A voltage sampling circuit comprises a rectification circuit, a voltage comparison circuit, an optoelectronic coupler, a level conversion circuit and a smoothed filter circuit which are sequentially connected with one another. The non-inverting input end of the voltage comparison circuit is connected with the anode of the rectification circuit output end through a resistor. The anode pin of the signal input end of the optoelectronic coupler is connected with the signal output end of the voltage comparison circuit. The collector pin of the optoelectronic coupler output end is connected with the signal input end of the level conversion circuit. The signal input end of the smoothed filter circuit is connected with the signal output end of the level conversion circuit. By adopting the optoelectronic coupler, the voltage sampling circuit provided by the utility model achieves sampling in an isolation way, makes control signals and sampling signals isolated and effectively prevents influence of external voltage networks on the control signals. The voltage sampling circuit has the advantages of high control precision and insignificant sampling errors, etc.

Design and construction of single phase pure sine wave inverter for photovoltaic application

Abstract: This paper discusses the design and construction scheme of an inverter system which converts the DC voltage collected from a photovoltaic (PV) array into AC voltage. The output is a pure sine wave, with the voltage and frequency of the standard grid output. The system consists of a Switch Mode Power Supply (SMPS) and full bridge inverter circuit with a passive filter. The power supply supplies the DC voltage needed to activate the optocouplers, which are connected to the switches of the full bridge circuitry. The optocouplers work as an isolation for the full bridge circuit. High frequency Pulse Width Modulated (PWM) pulses are generated by a microcontroller (PIC18F4431) and provided to the switches of full bridge connection. The full bridge inverter outputs a PWM sine which is later conditioned to pure sine by an L-C filter. Finally, the output voltage and current is measured and displayed on an LCD (Liquid Crystal Diode) display.

Filter for improved driver circuit efficiency and method of operation

Abstract: This disclosure provides systems, methods and apparatus for reducing harmonic emissions. One aspect of the disclosure provides a transmitter apparatus (2400). The transmitter apparatus (2400) includes a transmit circuit (2450) having an impedance determined by a complex impedance value. The transmitter apparatus further includes a driver circuit (2424) coupled to the transmit circuit (2450). The transmitter apparatus further includes a first filter circuit (2460) coupled between the driver circuit (2424) and a power source (2402). The first filter circuit (2460) is configured to substantially isolate emissions presented by the driver circuit (2424) to the power source (2402). The transmitter apparatus further includes a second filter circuit (2426) coupled between the driver circuit (2424) and the transmit circuit (2450) and configured to reduce emissions presented by the transmit circuit.

Voltage monitoring device

Abstract: A voltage monitoring device monitors voltage of each of battery cells connected in series to one another to configure an assembled battery. The device includes a capacitor circuit, a filter circuit, an input side connection switching unit, a potential difference detection unit, and an output side connection switching unit. The capacitor circuit includes a plurality of capacitors connected in series to one another. The filter circuit includes a plurality of resistors connected to an electrode terminal of each of the battery cells. The plurality of resistors are divided into a first resistor group and a second resistor group. The first resistor group is connected to a connection point between adjacent capacitors of the plurality of capacitors. The second resistor group is connected to an independent end of the plurality of capacitors. A resistance value of the first resistor group is smaller than a resistance value of the second resistor group.

Rfid module and rfid device

Abstract: An RFID module includes an RFIC element, a filter circuit, a matching circuit, and a radiating element. The filter circuit and the matching circuit define an RFID device. The filter circuit includes a first inductance element, a second inductance element, and a capacitor. The first inductance element and the second inductance element are of equal inductance, and are strongly magnetically coupled to each other so as to strengthen magnetic fluxes to each other. With this configuration, an RFID module and an RFID device that include a filter circuit to remove harmonic components of the RFIC element but are not large as a whole are constructed.

3d rf l-c filters using through glass vias

Abstract: Three-dimensional (3D) Radio Frequency (RF) inductor-capacitor (LC) band pass filters having through-glass-vias (TGVs). One such L-C filter circuit includes a glass substrate, a first portion of a first inductor formed on a first surface of the glass substrate, a second portion of the first inductor formed on a second surface of the glass substrate, and a first set of TGVs configured to connect the first and second portions of the first inductor. Additionally the L-C filter circuit can include a second inductor similar to the first inductor, and a metal-insulator-metal (MIM) capacitor formed between the first and second inductor, such that the first and second inductor are coupled through the MIM capacitor.

An error passivation approach to filtering for switched neural networks with noise disturbance

Abstract: In this paper, an error passivation approach is used to derive a new passive and exponential filter for switched Hopfield neural networks with time-delay and noise disturbance. Based on Lyapunov-Krasovskii stability theory, Jensen’s inequality, and linear matrix inequality (LMI), a new sufficient criterion is established such that the filtering error system is exponentially stable and passive from the noise disturbance to the output error. It is shown that the unknown gain matrix of the proposed switched passive filter can be determined by solving a set of LMIs, which can be easily facilitated by using some standard numerical packages. An illustrative example is given to demonstrate the effectiveness of the proposed switched passive filter.

Analog tuning of compact varactor-loaded combline filters in substrate integrated waveguide

Abstract: The design, fabrication and measurement of continuously tunable filters in single-layer SIWtechnology is presented in this paper. The filters are based on coupled coaxial resonators embedded into the dielectric and conveniently loaded with GaAs varactors. Firstly, a 2—pole filter demonstrator has been fabricated on a low-cost substrate showing a tunable centre frequency between 2.64 – 2.88 GHz with 1.27 – 3.63 dB insertion losses across the tuning range. Then, the application of this approach to post-fabrication fine tuning of narrow-band multi-pole filters is studied. Thus, a 2.8% FBW 3—pole Chebyshev filter is designed showing a good trade-off between tuning range, additional inband losses and fractional bandwidth variation.

Non-intrusive eye monitor system

Abstract: A system including a filter circuit, an error module, and a measurement module. The filter circuit receives, from a network device, an analog signal having jitter, generates an equalized signal based on digital feedback signals and the analog signal, and generates a recovered data signal based on the equalized signal. The recovered data signal includes data transmitted by the network device to the system. The error module generates an error signal based on the equalized signal and a threshold signal. The measurement module generates a multiple signals based on the recovered data signal, and the error signal. The multiple signals include the digital feedback signals and eye characteristic signals. The eye characteristic signals indicate characteristics of an eye diagram of the recovered data signal. The measurement module generates the digital feedback signals such that the eye diagram of the recovered data signal does not include the jitter.

An advanced control algorithm for Series hybrid active filter adopting UPQC behavior

Abstract: This paper presents an advanced comprehensive control approach for Hybrid Series Active Filter (HSeAF). This configuration consists of a series active filter (SeAF) and a shunt passive filter. The proposed control strategy, make this topology capable of compensate current distortions at the source and voltage harmonics and related issues from the load point of common coupling (PCC). The controller compels the HSeAF to perform as Unified power quality conditioner (UPQC) with similar behavior. The control algorithm employs the synchronous reference frames and the p-q theory to create an advanced controller for HSeAFs. This proposed algorithm treats diverse power quality issues simultaneously. With a fast and accurate response, it makes the PCC more reliable, cleans the power system from any current distortions, and also corrects the power factor. Hence, in this paper, the proposed control approach is studied and analyzed by simulations.

Power supply transmission method of high-power wireless induction type power supplier

Abstract: The invention discloses a power supply transmission method of a high-power wireless induction type power supplier, relating to a power supply module and a power receiving module. A power supply microprocessor is electrically connected with a first driving circuit and a second driving circuit which are respectively provided with two or more than two groups of metal-oxide semi-field-effect transistor arrays connected in parallel; the first driving circuit and the second driving circuit are electrically connected with a power supply resonance circuit with a capacitance array; and the power supply resonance circuit is electrically connected with a power supply coil array, so that the electromagnetic wave energy can be outputted to the power receiving module through frequency conversion and driving power adjustment, and through a main resonance capacitor and a secondary resonance capacitor connected with the power receiving coil array in parallel, and a synchronous rectifier connected withthe main resonance capacitor electrically, the direct-current power is outputted to outside by a high-frequency filter capacitor, a first power supply switch, a low-frequency filter capacitor and a second power supply switch in a filter circuit in sequence. In the power supply transmission method, due to the design of low impedance of a power transmission loop, not only can the high-power wireless power transmission be realized, but also the output power can be adjusted according to the load condition.

Investigation and resonances damping of multiple PV inverters

Abstract: This paper addresses the resonance problem in multiple PV inverters based microgrid. Unlike the performance of single grid-connected PV inverter where the resonance frequency is mainly fixed by the output LCL filter parameters, the multiple-PV inverter based microgrid system presents a more challenging picture where inverter interactions will excite complex resonances at various frequencies. As a result, line currents of inverters can be severely distorted even the control schemes and filter circuits are properly designed based on the single inverter model. This paper first develops a microgrid model based on discrete-time domain closed-loop Norton's equivalent circuits. Multiple resonances can then be evaluated using the developed model. To mitigate the resonances, this paper also designs a virtual harmonic resistance based active damping method. The proposed damping scheme is seamlessly incorporated into the conventional deadbeat current tracking schemes through the direct control reference modification. Simulation and experimental results are provided to validate the correctness of the developed resonance modeling and active damping methods.

Method for enhancing non-uniform variation grid width of light load efficiency of integrated switch DC-DC converter

Abstract: The invention discloses a method for enhancing the non-uniform variation grid width of the light load efficiency of an integrated switch DC-DC converter, a Buck-Boost converter in the invention adopts the design of a CSMC 0.5mu m CMOS process library, whole-circuit integration is realized except for a passive filter, the external filter inductance is 2.2mu H, and the filter capacitance is 1mu F. According to the requirements of input voltage and output voltage, the converter can work in three modes: Buck (voltage reducing), Buck-Boost (voltage reducing and boosting) and Boost (voltage boosting), the range of the input voltage is 2.5V-4.2V, the range of the output voltage is 1.5V-5V, and the working frequency is 5MHz. A non-uniform grid width modulation method is adopted in the whole load current range of 10mA-650mA. When the converter works at high frequency of 5MHz, the efficiencies of medium load and heavy load keep above 90 percent all the time, and the efficiency of light load (10mA) can reach above 80 percent. As the grid width of a switching tube is only changed and a control link of the working efficiency of an extra switching tube is not adopted, negative effects caused by frequency conversion control are eliminated fundamentally.

Charge-discharge two-way power converter for battery for electric car

Abstract: A charge-discharge two-way power converter for a battery for an electric car adopts the structure that an input port (In) connected with a storage battery and an output port (Out) connected with a grid are mounted outside a main circuit; the main circuit is connected with a control circuit; the main circuit comprises a battery side filter circuit (1), a like-polarity bi-directional DC/DC converter (2), and a high-frequency isolation DC/DC circuit (3), a three-phase three-level circuit (4) and a grid side filter circuit (5) which are sequentially connected; and the control circuit comprises a DSP main controller (6), an MCU auxiliary controller (7) and an LCD or 485 communication circuit (8). According to the invention, the circuit adopts comparatively less elements, the intelligent degree is high, self detection and fault protection functions are provided, the equipment and operation costs are saved, the conversion efficiency is high, the working process is quick, stable, and controllable, the size is small, the dynamic property is good, and the purposes of environmental protection and energy conservation are achieved.

High-efficiency LED constant current driving circuit

Abstract: The invention relates to a high-efficiency LED constant current driving circuit. The circuit comprises an input rectification filter circuit, a switch power supply management chip, an isolation switch transformer, a primary clamping circuit of the transformer, an output rectification filter circuit, an output current sampling circuit, a reference voltage generation circuit, a comparison circuit and a photoelectrical coupling circuit, wherein the input end of the input rectification filter circuit is connected with commercial AC electricity, while the output end is connected with a primary winding of the isolation switch transformer through the switch power supply management chip; the primary clamping circuit of the transformer is connected in parallel with the primary winding of the isolation switch transformer; the input end of the output rectification filter circuit is connected with the primary winding of the isolation switch transformer, while the output end is connected with LED load; an output current sampling circuit is connected in series with the LED load; the input end of the reference voltage generation circuit is connected with the LED load; and the input end of the comparison circuit is connected with the output current sampling circuit and the reference voltage generation circuit, while the output end is connected with the switch power supply management chip through the photoelectrical coupling circuit. The circuit improves the circuit integration degree, the reliability, the constant current precision and the circuit conversion efficiency.

Damping of input LC filter resonance based on virtual resistor for matrix converter

Abstract: An inductor-capacitor (LC) filter is normally required at the input of the matrix converter, to assist in the commutation of switching devices and to mitigate input current harmonics. However, its presence, in turn, often results in degradation of dynamic performance and instability of the system. This paper gives a simple procedure to select the input filter parameters for the matrix converter and four conventional methods to employ real resistors to damp filter oscillation. Then, an effective damping method is proposed by using a virtual resistor that can be connected in parallel with the filter capacitor. And it only changes the calculation of the modulation index of the space vector modulation strategy for matrix converter. This method is suitable for the microcontroller implementation without sacrificing the power efficiency. Simulation and experiment results are included to verify the proposed method.

Static reactive compensator and active power filter combined operation system and control method thereof

Abstract: The invention discloses a joint operating system of the static var compensator and active power filter and the control method, which is characterized in that an active power filter and a control device are added in the static var compensator. The control method of balance compensation of three-phase unbalanced loads is used to realize the compensation of load negative sequence current and the technology of specific subharmonic compensation is used to realize the decoupling control of SVC and APF, so as to guarantee the safe and stable operation of the joint operating system. The invention notonly has the basic functions of the SVC, but also improves the filtering performance of the passive filter through APF, suppresses possible resonance phenomena between the passive component and the power grid equivalent impedance, and can realize dynamic management on subharmonic waves.

Wideband tunable Love wave filter using electrostatically actuated MEMS variable capacitors integrated on lithium niobate

Abstract: A tunable bandpass filters with low insertion loss, sharp cut-off characteristics, wide bandwidth and wide tunability is strongly expected for future reconfigurable and cognitive wireless systems. In this study, a wideband tunable filter with the center frequency of 1.08 GHz was fabricated by directly integrating Love wave resonators and electrostatically actuated MEMS variable capacitors on a 15° Y LiNbO 3 wafer. The Love wave resonators have an extremely large electromechanical coupling coefficient ( k 2 ∼ 30%), providing wide bandwidth and wide tuning range. The 3 dB bandwidth was tuned from 146 MHz to 130 MHz by applying 15 V to one of the MEMS variable capacitors.

Methods and systems for interference rejection for low signals

Abstract: A radio device and a method to operate a non-heterodyne receiver are provided. The radio device is configured to receive a signal waveform and to provide a wake-up signal to a second communication circuit when the signal waveform is a valid communication request; wherein the second communication circuit switches from a power saving state to an operating state upon receiving the wake-up signal from the non-heterodyne receiver. The non-heterodyne receiver further including an Electromagnetic interference (EMI) rejection circuit, including a narrow band filter and a broadband filter to reject an EMI signal. A filter circuit for a narrow passband circuit is also provided. The filter including a buffer circuit; a crystal oscillator coupled to the output of the buffer circuit; and an inverting amplifier coupled in parallel to the crystal oscillator.