Showing papers on "RLC circuit published in 2012"

An LLCL Power Filter for Single-Phase Grid-Tied Inverter

Abstract: This paper presents a new topology of higher order power filter for grid-tied voltage-source inverters, named the LLCL filter, which inserts a small inductor in the branch loop of the capacitor in the traditional LCL filter to compose a series resonant circuit at the switching frequency. Particularly, it can attenuate the switching-frequency current ripple components much better than an LCL filter, leading to a decrease in the total inductance and volume. Furthermore, by decreasing the inductance of a grid-side inductor, it raises the characteristic resonance frequency, which is beneficial to the inverter system control. The parameter design criteria of the proposed LLCL filter is also introduced. The comparative analysis and discussions regarding the traditional LCL filter and the proposed LLCL filter have been presented and evaluated through experiment on a 1.8-kW-single-phase grid-tied inverter prototype.

Improved Design and Analysis of Self-Powered Synchronized Switch Interface Circuit for Piezoelectric Energy Harvesting Systems

Abstract: In piezoelectric energy harvesting (PEH), with the use of the technique named synchronized switch harvesting on inductor (SSHI), the harvesting efficiency can be greatly enhanced. Furthermore, the introduction of its self-powered feature makes this technique more applicable for stand-alone systems. In this paper, a modified circuit and an improved analysis for the self-powered SSHI (SP-SSHI) are proposed. With the modified circuit, direct peak detection and better isolation among different units within the circuit are achieved, both of which result in the further removal on the dissipative components. In the improved analysis, details in the open circuit voltage, switching phase lag, and intermediate voltages among different phases are discussed, all of which lead to a better understanding on the working principle of SP-SSHI. The total power dissipation from the piezoelectric source is also investigated. It is of concern but has not been considered in the previous literatures. Both analyses and experiments show that, in terms of the harvested power, the higher the excitation level, the closer between SP-SSHI and ideal (externally powered) SSHI; at the same time, the more beneficial the adoption of SP-SSHI treatment in PEH, compared to the standard energy harvesting (SEH) technique. Under the four excitation levels investigated, the SP-SSHI can harvest up to 200% more power than the SEH interface circuit.

Framework and Topology for Active Tuning of Parallel Compensated Receivers in Power Transfer Systems

Abstract: Wireless power transfer (WPT) based on magnetic coupling is becoming widely accepted as a means of transferring power over small to medium distances. An unresolved issue is the source and receiver resonance matching in multireceiver systems where the source operating frequency adjustment is not possible. This paper presents a framework to analyze the effect of parallel-compensated receiver detuning on the power transfer in WPT systems. Building on this analytical study, we present a new receiver design for WPT systems. The proposed design combines a parallel compensated resonant tank with a tristate boost converter. By synchronizing the tristate boost switching period with the half-period of the resonant tank voltage, we position the inherently discontinuous current pulse drawn by the tristate boost to control both active and reactive power flows from the resonant circuit. Controllable reactive current can be used effectively to emulate appropriate inductance or capacitance to tune the resonant tank and achieve optimal power transfer.

On the application of radio frequency voltages to ion traps via helical resonators

Abstract: Ions confined using a Paul trap require a stable, high voltage and low noise radio frequency (RF) potential We present a guide for the design and construction of a helical coil resonator for a desired frequency that maximises the quality factor for a set of experimental constraints We provide an in-depth analysis of the system formed from a shielded helical coil and an ion trap by treating the system as a lumped element model This allows us to predict the resonant frequency and quality factor in terms of the physical parameters of the resonator and the properties of the ion trap We also compare theoretical predictions with experimental data for different resonators, and predict the voltage applied to the ion trap as a function of the Q factor, input power and the properties of the resonant circuit

Lossy / lossless floating / grounded inductance simulation using one DDCC

Abstract: In this work, we present new topologies for realizing one lossless grounded inductor and two floating, one lossless and one lossy, inductors employing a single differential difference current conveyor (DDCC) and a minimum number of passive components, two resistors, and one grounded capacitor. The floating inductors are based on ordinary dual-output differential difference cur- rent conveyor (DO-DDCC) while the grounded lossless inductor is based one a modified dual-output differential difference current conveyor (MDO-DDCC). The proposed lossless floating inductor is obtained from the lossy one by employing a negative impedance converter (NIC). The non-ideality effects of the active element on the simulated inductors are investigated. To demonstrate the perform- ance of the proposed grounded inductance simulator as an example, it is used to construct a parallel resonant circuit. SPICE simulation results are given to confirm the theoretical analysis.

A Generalized Dual-Band Wilkinson Power Divider With Parallel $L, C,$ and $R$ Components

Abstract: A generalized model of a two-way dual-band Wilkinson power divider (WPD) with a parallel LC circuit at midpoints of two-segment transformers is proposed and compared with that of a conventional two-way dual-band WPD with a parallel LC circuit at the ends of two-segment transformers. The sum of power reflected at an output port and power transmitted to an isolation port from another isolation port in the proposed divider is smaller than that in the conventional divider. Therefore, wide bandwidths for S22, S33, and S32 can be expected for proposed dividers. In the case of equal power division, frequency characteristics of return loss at output ports and isolation of the proposed divider are wider than those of the convention one. The resonant frequencies of LC circuits in the proposed divider and a conventional divider are equal; however, the inductance L used in the proposed divider is always smaller than that in the conventional divider. Design charts and calculated bandwidths as a function of frequency ratio from 1 to 7 are presented. In experiments, two symmetrical and two asymmetrical circuits were fabricated. The experimental results showed good agreement with theoretical results.

Bilayer-fish-scale ultrabroad terahertz bandpass filter.

Abstract: A bilayer fish-scale metamaterial is experimentally demonstrated to function as a broad bandpass filter in the terahertz regime. The measured 3 dB-bandwidth for normal incidence is 1.13 THz with a high transmittance. The measured transmission spectrum is described well by a model based on an RLC circuit and multiple reflections. The filter is relatively insensitive to incidence angles up to 45°.

Development of an Efficient Solid-State Fault Current Limiter for Microgrid

Abstract: This paper deals with the development of a resonant-type solid-state fault current limiter (SSFCL), suitable for distribution-generation (DG) units in the microgrid. The proposed SSFCL has both series and parallel resonant circuits that are tuned at the supply frequency. In normal condition, the SSFCL exhibits very low impedance through the series resonant circuit. In fault conditions, the SSFCL offers very high impedance by the parallel resonant circuit. Upon fault occurrence, an auto-triggered silicon control rectifier (SCR) inserts the parallel resonant circuit in the load current path. In addition to self-controlling capability of the proposed SSFCL, it can be controlled using an external command generated by a fault detection algorithm. Therefore, with a very simple structure, it provides adequate certainty of operation. A prototype single-phase SSFCL is simulated in the Electromagnetic Transient Program (EMTP) and tested. The results show that the proposed SSFCL can significantly reduce the fault current in a short time.

Wireless power system and resonant frequency changing method thereof

Abstract: This specification provides a wireless power system capable of changing a resonant frequency and a resonant frequency changing method thereof. To this end, a wireless power receiver according to one exemplary embodiment includes a power receiving unit having a receiving side resonant circuit provided with at least one inductor and at least one capacitor, and configured to receive a wireless power signal, the wireless power signal being generated based on a resonance phenomenon between the receiving side resonant circuit and a transmitting side resonant circuit of a wireless power transmitter, and a power reception control unit configured to control the power receiving unit to change a connection between the at least one inductor and the at least one capacitor so as to change a resonant frequency corresponding to the wireless power signal.

Nonisolated ZVZCS Resonant PWM DC–DC Converter for High Step-Up and High-Power Applications

Abstract: The demand for nonisolated high step-up dc-dc converters in applications such as dc backup energy systems for UPS, photovoltaic and fuel cell systems, and hybrid electric vehicles has been gradually increasing. This paper proposes nonisolated step-up dc-dc converters with an improved switching method. The proposed converter shows zero-voltage switching turn-on of the switches in continuous conduction mode as well as reduced turn- off switching losses owing to the switching method that utilizes Lr-Cr resonance in the auxiliary circuit. Also, as a result of the proposed switching method, the switching losses associated with diode reverse recovery become negligible even in the small duty cycle. The capacitance in the auxiliary circuit is significantly reduced compared to the pulsewidth modulation method. The duty cycle loss is further reduced resulting in increased step-up ratio. Experimental results from a 2-kW prototype of a two-phase interleaved version are also provided to validate the proposed concept.

Method and device for transmission of power

Abstract: FIELD: electricity. ^ SUBSTANCE: in a method to transmit power along an overhead radial power transmission line from a step-down substation to loads distributed along a radial line at the frequency of 50-60 Hz the power is sent additionally to an end load of the radial line from the step-down substation via a rectifier, a frequency converter and a resonant circuit along a single-wire line at a resonant frequency of 0.4-100 kHz to a resonant circuit, a rectifier and a network inverter, the network inverter 50-60 Hz is attached at the end load to the radial overhead line, and then power is sent from the end load along an overhead radial line to other distributed loads connected to the radial line. Power to the end load of the radial line is sent along a single-wire cable line or a single-wire line by its placement on supports of the overhead radial line. The device to transfer power comprises at the substation a rectifier, a frequency converter and a resonant circuit, the medium outlet of which is connected to a single-wire line, the single-wire line is connected at the end load with the end of the radial line via a resonant circuit, a rectifier and a network inverter. ^ EFFECT: higher reliability of power supply, reduced losses in a power transmission line and increased power transmitted in lines. ^ 6 cl, 3 dwg

Power supply device

Abstract: PROBLEM TO BE SOLVED: To provide a resonance type power supply device for non-contact charge which can suppress decline in charge efficiency without increasing the size, when a relative position between a primary coil and a secondary coil is deviated from an appropriate positionSOLUTION: A resonance type power supply device for non-contact charge includes: a primary side resonance circuit including a primary coil to which AC power is supplied to generate a magnetic field; current detection means detecting a primary side current of the primary side resonance circuit; voltage detection means detecting a primary side voltage of the primary side resonance circuit; power factor calculation means calculating a power factor based on the primary side current and primary side voltage; and characteristic adjusting means comparing the power factor with a threshold value corresponding to target efficiency and adjusting characteristics of the primary resonance circuit to increase the power factor when the power factor is below the threshold value

Circuit arrangement and method for interrupting a current flow in a dc current path

Abstract: A DC current path for DC power transmission includes at least a first switching element and a second switching element connected in series. A resonance circuit is configured to be connectable in parallel to the series connection of the at least one first switching element and second switching element by means of a switch.

Low noise oscillators

Abstract: An oscillator having: a transistor; a resonant circuit coupled between an output electrode of the transistor and a control electrode of the transistor; and a dc bias circuit for the transistor. The dc bias circuit comprises: a voltage producing circuit and a differential amplifier. The differential amplifier includes: a first input coupled to a fixed reference voltage; a second input coupled to the voltage producing circuit, such voltage producing circuit producing a voltage at the second input of the difference amplifier related to current passing through the output electrode of the transistor; and an output coupled to the control electrode of the transistor.

Non-isolated resonant converter

Abstract: A non-isolated resonant converter is provided. The provided non-isolated resonant converter includes a switch circuit, a resonant circuit and a rectifying-filtering circuit. The switch circuit, the resonant circuit and the rectifying-filtering circuit are sequentially connected. The resonant circuit includes an auto-transformer, a capacitor and an inductor, wherein the capacitor and the inductor are connected to the auto-transformer. The configuration of the provided non-isolated resonant converter has small size, low loss and high power density.

A Motor-Friendly Quasi-Resonant DC-Link Inverter With Lossless Variable Zero-Voltage Duration

Abstract: Two quasi-resonant dc-link (QRDCL) inverter topologies are discussed for motor-friendly application. For the control of an inverter, a modified space-vector pulsewidth modulation is implemented, which requires only two resonant cycles per switching period and helps in better utilization of dc-link voltage. The first topology is tested experimentally with a 34-m-long cable connected between inverter and induction machine for reduced voltage overshoot at motor-side cable end and common-mode (CM) voltage. Even though results are satisfying, a freewheeling interval of this topology produces high losses. So a new motor-friendly QRDCL inverter with lossless variable zero-voltage duration is proposed. In this topology, during a zero-voltage interval, energy is stored in a capacitor rather than an inductor. No current is freewheeling through inverter switches, and it clearly helps in reducing the losses under a low-modulation index region. Simulation results are presented to verify the validity of the proposed inverter and its motor-friendly characteristics.

Litz wire battery powered device

Abstract: A medical instrument is disclosed. The medical instrument includes a housing and a handle for gripping by a user, an end effector coupled to the handle and having at least one electrical contact, a battery, and a radio frequency (RF) generation circuit coupled to and operated by the battery. The RF generation circuit is operable to generate an RF drive signal and to provide the RF drive signal to the at least one electrical contact, wherein the RF generation circuit is supported by the housing. The RF generation circuit includes a resonant circuit that includes at least one inductive element constructed of litz wire.

Resonant tracking non-contact power supply device and power supply method

Abstract: The invention discloses a resonant tracking non-contact power supply device and a resonant tracking non-contact power supply method and aims to mainly solve the problems that the transmission efficiency and transmission distance are reduced and induction voltage is sensitive to load change caused by the change of a resonant point in an LC resonant non-contact power supply. An excitation source with adjustable frequency and amplitude is formed through an adjustable switch power source (102) and a half-bridge switch (103) and is applied to a resonant circuit consisting of an emitting coil (112)and a resonant capacitor (113); a current signal in the resonant circuit is acquired by using a current sampler (104); an automatic resonant frequency tracking circuit consists of a comparator (105),a phase discriminator (106) and a controllable oscillator (107); when the resonant point changes, an excitation frequency is automatically adjusted and an automatic excitation voltage adjusting circuit consists of a wave detecting and filtering circuit (109), an error amplifier (110) and the adjustable switch power source (102) to automatically adjust the excitation voltage when a load changes, so a load voltage is basically constant. The resonant tracking non-contact power supply device can overcome the effects caused by resonant frequency change and load change and is applicable for the occasion of close-range and high-efficiency non-contact power transmission.

The analytical basis for the resonances and anti-resonances of loop antennas and meta-material ring resonators

Abstract: Interest in the electromagnetic properties of loop structures has surged with the recent appearance of split-ring resonator meta-materials (SRRs) and nano-antennas. Understanding the resonances, anti-resonances, and harmonics of these loops is key to understanding their response to a wide range of excitation wavelengths. We present the classical analytical solution for the input impedance of a loop structure with circumference on the order of the wavelength, and we show how to identify these resonances from the function. We transform the classical solution into a new RLC formulation and show that each natural mode of the loop can be represented as a series resonant circuit, such that the full response function can be resolved by placing all of these circuits in parallel. We show how this formulation applies to SRRs.

Wireless power transmission device

Abstract: A wireless power transmission device comprises: a detection coil (L1) and a capacitor (C1) constituting a resonance circuit; and an oscillation circuit (21, 22) for exciting the detection coil with a high-frequency current. The oscillation circuit can generate the high-frequency current in accordance with a detection frequency for detecting the presence of an electric device and a metal. The wireless power transmission device further comprises: an output detection circuit (24) for generating output voltage (Vs) in accordance with the excitation current flowing through the detection coil (L1); a presence detection circuit (12) for detecting the presence of the electric device and the metal on the basis of the output voltage (Vs) obtained by exciting the detection coil (L1) with a high-frequency current having the detection frequency; and a detection condition changing circuit (12) capable of executing an initial value setting mode for changing a detection condition of the presence detection circuit in accordance with the resonance characteristics determined by the detection coil (L1) and the capacitor (C1).

Detection apparatus, electric power receiving apparatus, electric power transmission apparatus, wireless electric power transmission system, and detection method

Abstract: A method for wireless power transmission includes obtaining, via a Q-value circuit, first and second voltages at respective first and second nodes of a resonance circuit The first and second voltages are effective to determine if foreign matter is present in a space affecting wireless power transmission The method includes controlling a switching section between the Q-value circuit and the resonance circuit such that at least a part of the electric power transmission process occurs at a different time than when the first and second voltages are obtained

Wireless power transmitter

Abstract: An example wireless power transmitter is configured for wirelessly transmitting a signal to a power receiving apparatus including a first resonance circuit and a load circuit. The first resonance circuit includes a power receiving coil and a first capacitor. The example wireless power transmitter includes a power supply that has a variable oscillation frequency and generates a signal having the oscillation frequency; a second resonance circuit that transmits the signal to the power receiving apparatus; a measuring unit that measures a signal reflection coefficient, the signal reflection coefficient being determined based on magnitude of the signal and magnitude of a signal reflected on the second resonance circuit to the power supply; and a controller that detects a value of the oscillation frequency making the signal reflection coefficient smaller than or equal to a threshold value, and calculates an electromagnetic coupling coefficient between the power transmission coil and the power receiving coil based on the detected value.

Detection apparatus, power receiving apparatus, non-contact power transmission system and detection method

Abstract: Disclosed herein is a detection apparatus including: a resonant circuit provided with a Q-factor measurement coil and one or more capacitors to serve as a circuit for receiving pulses; a response-waveform detecting section configured to detect the waveform of a response output by the resonant circuit in response to the pulses; and a Q-factor measuring section configured to measure a Q factor of the resonant circuit from the response waveform detected by the response-waveform detecting section. It is possible to increase the precision of detection of a metallic foreign substance existing between a power transmitting side and a power receiving side.

Power transmitting device, power receiving device, and non-contact charging method

Abstract: In a non-contact charging method, variable information with which a resonance frequency of a resonance circuit of an equipment device having maximum charging power as the power transmitting frequency, and a resonance frequency or a Q value of a resonance circuit of a power receiving unit of an equipment device other than the equipment device having the maximum charging power as a resonance frequency or a Q value for charging depending on each charging power, and transmits to each equipment device variable information corresponding to each equipment device.

Rf coil and magnetic resonance imaging device

Abstract: To provide a technique for sufficiently eliminating magnetic coupling between RF coils and improving image quality when a multi-element multi-tuned RF coil is used as a receive RF coil for an MRI device. In the invention, each of RF coils which constitute a multi-element multi-tuned RF coil which is used as a receive RF coil for an MRI device is provided with an inter-coil magnetic coupling prevention circuit which resonates at each frequency to which each RF coil is tuned and provides a high impedance. The inter-coil magnetic coupling prevention circuit adjusts an inductor and a capacitor so that both of a circuit on the side of a pre-amplifier viewed from both ends of a signal reception circuit and a circuit on the side of the signal reception circuit viewed from both ends of a serial resonance circuit connected to the pre-amplifier resonate at a plurality of frequencies to which the respective RF coils are tuned.

Proposal for a new resonance adjustment method in magnetically coupled resonance type wireless power transmission

Abstract: In a magnetically coupled resonance system which enables intermediate-range power transmission, over 100 high Q is required in the power transmission resonance circuit. In other words, high-precision adjustment of the resonance frequency is necessary. In this paper, we are proposing a pure-electronic resonance frequency adjustment circuit which does not require any complicated controls. With this proposal, the resonant condition can be maintained without using high-precision parts or mechanical adjustment mechanisms.

An Efficient Resonant Gate-Drive Scheme for High-Frequency Applications

Abstract: Silicon carbide (SiC) and gallium nitride (GaN) devices have been found to withstand high voltages without showing degradation and can be switched at high frequencies, making them attractive for high-power drives. Although Sic/GaN devices can be operated at high temperature and high frequencies, it is important to develop gate-drive circuits to efficiently turn on and off these devices at high speeds. This paper proposes a resonant gate-drive circuit that aims at reducing the power loss associated with high-frequency switching of power insulated gate bipolar transistors/metal–oxide–semiconductor field-effect transistors. The main thrust of the circuit is its application to the motor-drive industry. The proposed circuit is compared with traditional gate-drive circuits from the points of view of power consumption and switching speed. Experimental results are given to illustrate the concept. Test results show that the power consumption using the proposed circuit reduces by a factor of greater than 5 compared with a traditional gate-drive circuit.

Multi-radiofrequency impedance control for plasma uniformity tuning

Abstract: Circuits, methods, chambers, systems, and computer programs are presented for processing wafers. A wafer processing apparatus includes top and bottom electrodes inside a processing chamber; a first, second, third, and fourth radio frequency (RF) power sources; and one or more resonant circuits. The first, second, and third RF power sources are coupled to the bottom electrode. The top electrode may be coupled to the fourth RF power source, to electrical ground, or to the one or more resonant circuits. Each of the one or more resonant circuits, which are coupled between the top electrode and electrical ground, include a tune-in element operable to vary a frequency-dependent impedance presented by the resonant circuit. The wafer processing apparatus is configurable to select the RF power sources for wafer processing operations, as well as the connections to the top electrode in order to provide plasma and etching uniformity for the wafer.

Control of ZCS-SR Inverter-Fed Voltage Multiplier-Based High-Voltage DC–DC Converter by Digitally Tuning Tank Capacitance and Slightly Varying Pulse Frequency

Abstract: Conventional pulse-frequency-modulated (PFM) zero-current switching series resonant (SR) inverter-fed voltage-multiplier-based high-voltage dc power supplies have nearly zero switching loss. However, they have limitations of poor controllability at light load and large output voltage ripple at low switching frequencies. To address these problems, this letter proposes a new control scheme that is based on digitally tuning tank capacitance and slightly varying pulse frequency of SR inverter. For the realization of the proposed control approach, the tank circuit of the resonant inverter is made up of several tank capacitors that are switched into or out of the tank circuit by electromechanical switches. By digitally modulating the tank capacitance, the output voltage changes in steps. The regulation of output voltage between two adjacent steps is achieved by slightly varying the pulse frequency. The proposed control scheme has several features, namely, a wide range of output voltage controllability even at light loads, less output voltage ripple, and less current stress on the inverter's power switches at light loads. Therefore, the proposed control approach alleviates most of the problems associated with conventional PFM. Experimental results obtained from a scaled-down laboratory prototype are presented to verify the effectiveness of the proposed system.