Showing papers on "RLC circuit published in 1989"

Resonant DC/DC converter with class-E inverter and class-E rectifier

Abstract: A new type of high-frequency high-efficiency resonant DC/DC converter is proposed, analyzed, and verified experimentally. It is called a class-E converter because it consists of a class-E inverter and a class-E rectifier. The class-E rectifier acts as an impedance inverter and is compatible with the class-E inverter. Consequently, the converter can operate with load resistances from a full load to infinity while maintaining zero-voltage switching of the transistor in the inverter and the diode in the rectifier. It operates safely with a short circuit at the output. Because of a high value of the load quality factor Q/sub 1/, a narrow frequency range suffices to regulate the DC output voltage over the whole load range. The measured relative bandwidth was delta f/f/sub min/=42.2% as the load resistance was varied from 70 Omega to open circuit. The measured efficiency at the full load was 89% with a 9 W output power at 1 MHz. A family of class-E/sup 2/ resonant DC/DC power converters is given. The possibility of reduction of class-E/sup 2/ converters to lower-order resonant and pulse-width-modulation converters is shown. >

Parallel resonant converter with zero voltage switching

Abstract: A parallel resonant converter as disclosed having in one embodiment a variable inductance and having a control circuit which operates the switches of the converter under zero voltage switching conditions and under continuous conduction mode by maintaining the quality factor of the resonant circuit generally equal to the DC conversion ratio.

Constant frequency zero-voltage-switching multi-resonant converter

Abstract: A zero-voltage multi-resonant converter that operates at constant frequency. In the zero-voltage multi-resonant converter, the resonant circuit is formed in a π-network with resonant capacitors connected in parallel with the switches. In practicing the present invention, certain rules are applied to derive a CF ZVS-MRC from a PWM converter. In particular, one resonant capacitor is placed in parallel with the active switch, which may be either uni-directional or bi-directional, the rectifying switch is replaced by another active switch, which may also be uni-directional or bi-directional, another resonant capacitor is placed in parallel with the other active switch, and an inductor is inserted in the loop containing the two switches. This loop can also contain voltage sources and filter or blocking capacitors.

Parallel resonant DC link circuit-a novel zero switching loss topology with minimum voltage stresses

Abstract: A parallel-resonant DC link (PRDCL) circuit topology is presented as a way to realizing zero-switching-loss, DC-AC high switching frequency power conversion. The circuit is used as an interface between DC voltage supply and the voltage-source PWM (pulse-width-modulated) inverter. It provides a short zero-voltage period in the DC link of the inverter to allow zero-voltage switching to take place in the PWM inverter. The peak voltage stress on the PWM inverter switches is limited to the DC supply voltage. Another significant advantage of the proposed circuit is that the inverter can be controlled by the conventional PWM strategy. The circuit is systematically analyzed, and its operation principle is explained in detail. Design considerations and formulae are also presented. A complete zero-voltage-switching DC-AC converter system consisting of the proposed circuit and the PWM inverter is simulated on computer. >

Lossless gate driver circuit for a high frequency converter

Abstract: A high efficiency gate driver circuit for driving a power switching device of a high frequency converter includes a series resonant circuit for making resonant transfers of energy between the input capacitance of the power switching device and a storage capacitor to achieve substantially lossless gate switching. An ac switch couples the resonant circuit to the junction between upper and lower switching devices connected in a half-bridge configuration. The upper and lower switches of the half-bridge function to maintain the power switching device in either an ON-state or an OFF-state, respectively, depending on the transfer of energy being made. Timing circuitry ensures proper gating of the switching devices relative to operation of the ac switch.

Fluorescent dimming ballast utilizing a resonant sine wave power converter

Abstract: In a method or combination, a DC voltage supply, a converter including a series or a parallel resonant circuit (LR, CR, TR) for converting the DC voltage to a sinusoidal current, and a load (T1, T2) including at least one fluorescent lamp responsive to the sinusoidal current to effect excitation of the lamp.

High frequency switched mode resonant commutation power supply

Abstract: A forward switched mode converter power supply of a resettable type, in which leakage inductance in the input circuit, the parallel inductance of the transformer and the parasitic capacitance of the switching means provides a resonant circuit for recirculating commutation energy, so that the voltage across the switching means is reduced essentially to zero at the beginning of each switching cycle to prevent loss of the commutation energy

Neutral forming circuit

Abstract: Prior neutral forming circuits for use in developing a neutral voltage for loads coupled to an inverter have been unduly large and heavy or have required that the inverter be operated by a half bridge control which causes less easily filtered harmonics to be produced in the inverter output. In order to overcome these problems, a neutral forming circuit includes first and second impedances coupled together at a junction to form a series combination which is coupled across a pair of DC link conductors coupled to an inverter input and a third impedance coupled between the junction and a neutral terminal at which the neutral voltage is formed, the first through third impedances forming a resonant circuit having a resonant frequency substantially equal to the output frequency of the inverter.

Static power conversion apparatus using a high frequency series resonant DC link

Abstract: A high efficiency power converter is achieved which eliminates the needs for self-commutated devices and requires only twelve thyristors for full double bridge AC/AC power conversion. The system utilizes a series resonant DC link between the AC/DC and DC/AC converters. The DC resonant circuit functions as a commutating circuit which ensures turn off of all twelve thyristors by providing the necessary zero current instants. A significantly improved sinusoidal current waveform can be obtained on both the input and the output compared to conventional high power converters by the use of high frequency pulse density modulation.

Transistor conduction-angle control for a series-parallel resonant converter

Abstract: A DC to DC series-parallel resonant converter (10) having a plurality of switches (Q1-Q4) which are switched alternatively between on and off states to cause electrical current to flow alternatively in first and second directions through a series-resonant circuit (60) Including a variable frequency ramp generator (28) having a reset input (R) for casuing an output ramp signal produced at an output to drop to zero in response to each reset signal; a comparator (30) having an input coupled to the output of the ramp signal generator, a second input for controlling the output DC voltage of the series-parallel resonant circuit and an output which changes level each time the ramp signal reaches the magnitude of the second input; a bistable circuit (32) having first and second outputs (Q, Q) for respectively outputting first and second signals, the output signals changing in response to a change in the output signal of the comparator coupled to the input; a pulse generator (26), coupled to the series-parallel resonant circuit for producing an output pulse train with an output pulse occurring each time the flow of current through the series-resonant circuit changes from one of the first and second directions to another of the first and second directions, the output pulses being applied to the reset input of the variable frequency ramp generator to regulate the frequency of the output ramp signal.

Bilateral series resonant inverter for high frequency link UPS

Abstract: A description is given of a bilateral series-resonant inverter for high-frequency link uninterruptible power supply. The inverter consists of a zero-current-switched series-resonant power converter, a high-frequency transformer, and a zero-current-switched cycloconverter, whereby bidirectional power flow is possible and high efficiency is obtained. The output voltage is regulated by controlling the resonant tank energy, and the switching pattern of the cycloconverter is fixed to obtain the high-frequency transformer. A novel control scheme to minimize the output ripple voltage is suggested and verified through computer simulation, and the effects of the circuit parameters on the output voltage ripple are discussed. >

Class E/sup 2/ narrow-band resonant DC/DC converters

Abstract: A family of seven class E/sup 2/, narrowband, high-frequency, high-efficiency, resonant DC/DC converters is introduced, and an experimental example is given. Class E zero-voltage-switching operation of both the inverter and rectifier components is maintained for loads ranging from a full load to an open circuit, significantly reducing switching losses and yielding high efficiency at high frequencies. Because of a high loaded quality factor Q, the current in a resonant circuit is sinusoidal and the output voltage is very sensitive to the operating frequency. Therefore, narrowband FM control of the output voltage is achieved as the load varies from a full load to an open circuit. The measured frequency range Delta f/f/sub min/ was only 20.9% for load resistance from 30 Omega to infinity. The circuits have high power density and fast dynamic response, produce low electromagnetic interference (EMI) and noise, and operate safely with a short circuit at the output. The relationship between pulse width-modulated (PWM) converters and resonant converters is shown. The class E/sup 2/ converters are especially suitable for applications in measurement instrumentation. >

Series resonant inverter and method of lamp starting

Abstract: The method of starting fluorescent lamps includes energizing the lamp and its filaments, in a cold condition, with voltages and currents considerably in excess of (and integer multiples of) normal operating parameters. This high power is supplied for either a predetermined time (on the other of 100 milliseconds) or until lamp starting is sensed. The power conditioning electronics improves the power factor by using normal inverter current to charge a capacitor so that, as full wave rectified voltage from a bridge falls, current can be supplied to the inverter from the charged capacitor. The full wave bridge rectifier includes two diodes and two silicon controlled rectifiers, the latter energized by secondary windings of a transformer which carries current under normal inverter operating conditions. In the event that operating parameters of the inverter exceed a threshold, however, current through the primary of the transformer is shunted away, thus removing the triggering current from the SCRs. The SCRs as a result open circuit the bridge and as a consequence power is removed from the inverter to provide for shock protection. Manufacturability of the power conditioning electronics is improved by using a single saturable core to control the conduction duration of the switches in the inverter. The control arrangement inhibits conduction of a non-conducting one of the switches until the voltage in the series resonant circuit peaks.

Model and simulations of hysteresis in magnetic cores

Abstract: The authors present simulations of the hysteresis experienced by a ferromagnetic core as it dissipates energy in an RLC circuit. The calculations utilize the Hodgdon theory of ferromagnetic hysteresis, along with a model of the core geometry. The theory allows for both rate-independent and rate-dependent effects, with the latter often having a marked influence on the hysteresis. The hysteresis theory involves a number of parameters, some of which are obtained from major loop data and the rest of which are deduced from circuit data. Results obtained for three materials-CN20, C2025, and Vitrovac-show that the predicted voltage waveform can be brought into agreement with experiment. >

Optimal topologies of resonant DC/DC converters

Abstract: Generalized and optimal topologies of zero-voltage-switching and zero-current-switching resonant DC/DC power converters are presented. It is shown that many equivalent topologies of the converters can be derived from each of the generalized topologies. The generalized topologies of the converters show clearly which of the parasitic capacitances and inductances can be absorbed into the LC resonant circuit. Utilizing this fact, optimal topologies that are the most suitable for high-frequency operation are derived. In the optimal topologies, the greatest possible number of parasitic reactances is included harmlessly in the resonant circuit. Optimum layout and component selection guidelines for the converters are given. High-order resonant converters are also developed. >

High-frequency high-order parallel resonant converter

Abstract: A novel approach to the analysis of design of a high-order high-frequency LCC-type capacitive coupled parallel resonant converter (PRC-LCC) operated in the continuous-conduction mode is presented. The presence of an additional capacitor in series with the inductance of the conventional PRC results in a converter with more desirable control characteristics. It is shown that, at switching frequencies lower than the resonant frequency, the gain of the LCC-type converter is lower than the grain of the conventional PRC. This facilitates the converter design with a lower turn-ratio transformer and therefore allows for a higher operating frequency. The complete state-plane diagram of the LCC-type converter, from which a set of steady-state characteristic curves is plotted, is given. Various design curves for component value selections and device ratings are given. A design example with computer simulation results is presented. >

A New Type of Intermittency in an Electronic Circuit

Abstract: An intermittency which has a different origin from the Pomeau-Manneville types is studied in a coupled nonlinear LCR circuit. This type of intermittency has a close relation to the multiplicative noise process. The electronic circuit is made up of inductors, resistors and capacitor diodes. An experimental study is done in this system. The results are compared with those of a phenomenological theory based on the multiplicative noise process. More· over, a numerical calculation is also carried out on the equations for the present circuit with observed nonlinear characteristics of diodes. Satisfactory agreement between the exper· imental and calculated results is obtained.

High efficiency power amplification for microwave and millimeter frequencies

Abstract: A novel technique for realizing high-efficiency operation of power amplifiers at microwave frequencies is demonstrated. This approach features third-harmonic-peaking Class-F amplifier operation. A novel third-harmonic-peaking circuit using drain-source capacitance in conjunction with a series LC resonant circuit is used to provide maximum power-added efficiency. Simulation data indicate that this amplifier provides an 8% improvement over the conventional Class-B approach at X-band. >

The Pierce diode with an external circuit. I. Oscillations about nonuniform equilibria

Abstract: The nonuniform (nonlinear) equilibria of the classical (short circuit) Pierce diode and the extended (series RLC external circuit) Pierce diode are described, and the spectrum of oscillations (stable and unstable) about these equilibria are worked out. It is found that only the external capacitance alters the equilibria, though all elements alter the spectrum. In particular, the introduction of an external capacitor destabilizes some equilibria that are marginally stable without the capacitor. Computer simulations are performed to test the theoretical predictions for the case of an external capacitor only. It is found that most equilibria are correctly predicted by theory, but that the continuous set of equilibria of the classical Pierce diode at Pierce parameters (α=ωpL/v0) that are multiples of 2π are not observed. This appears to be a failure of the simulation method under the rather singular conditions rather than a failure of the theory.

Filter equipment for power lines

Abstract: Filter equipment for power lines has a double-tuned shunt filter (F1) which has a series resonance circuit (C1, L1) connected in series with a parallel resonance circuit (C2, L2). The capacitor banks of the two resonance circuits are formed so as to have opposite signs on the temperature coefficent of the capacitor capacitance.

High-frequency operating circuit for a fluorescent lamp

Abstract: To provide for automatic disconnect upon failure of a filament of one (E2)f the electrodes of a fluorescent lamp, an output terminal (P1) of a power rectifier is connected through the filament to a supply terminal (P3) of a push-pull frequency generator formed by two transistors (T1, T2). The fluorescent lamp (LP) has its other electrode (E1) connected to a common terminal between two transistors (T1, T2) of the high-frequency generator. A series resonance circuit (L1, C6, C8) is capacitor-coupled (C7) to the lamp. Upon failure of the filament of the first electrode (E2), or removal of the lamp from its lamp sockets, power supply to the transistor oscillator or frequency generator circuit is interrupted, so that the oscillator is deenergized; upon insertion of an operative lamp in the lamp circuit, the circuit is closed so that the fluorescent lamp is automatically started by the push-pull oscillator (3) formed by the two transistors (T1, T2) and associated circuitry.

An RLC matching network and application in 1-20 GHz monolithic amplifier

Abstract: Design equations are derived for an RLC matching network. The equations can be applied in lossy-match MESFET amplifiers to give flat gain and low SWR (standing wave ratio) over wide bandwidths. Experimental results are presented for a monolithic 1-20-GHz amplifier. The theory is useful, in general, for the design of wideband, resistive matching networks for capacitive loads with a small series resistance. >

High frequency power amplifier circuit

Abstract: A first high inductor is connected between a ground point and the base of a high frequency amplifying transistor whose emitter is grounded. A first capacitor is connected between a mid-point of the first inductor and the ground point. A second inductor is connected between the collector of the transistor and a power source terminal. A second capacitor is connected between a mid-point of the second inductor and the ground point. The first inductor connects the base of the transistor to ground in a DC mode, and cooperates with the first capacitor to form a first series resonant circuit. The resonance frequency of the circuit is equal to half of the frequency "f" of an input signal to the transistor. The resonant first series circuit allows a signal of the f/2 frequency generated on the base side of the transistor to flow to the ground point. The second inductor feeds electric power to the collector of the transistor, and cooperates with the second capacitor to form a second series resonant circuit. The resonance second series resonant frequency of the circuit is equal to half of the frequency "f" of an input signal to the transistor. The second series resonant circuit allows a signal of the f/2 frequency generated on the collector side of the transistor to flow to the ground point.

High efficiency gate driver circuit for a high frequency converter

Abstract: A high efficiency gate driver circuit for driving a power switching device of a high frequency power converter utilizes a series resonant circuit to reduce or substantially eliminate turn-on switching losses. The resonant circuit comprises the input capacitance of the power switching device and an inductance connected in series between the upper and lower switching devices of a half-bridge driver circuit. During device turn-on, the input capacitance resonates up to a voltage level approximately twice that of the gate drive power supply, and turn-on is substantially lossless. The input capacitance is prevented from discharging back to the supply by a Schottky diode connected in series between the supply and the upper switching device of the half-bridge. During device turn-off, the input capacitance discharges through the lower switching device.

High-frequency parallel resonant converter for X-ray generator utilizing parasitic circuit constants of high voltage-transformer and -cables

Abstract: The authors describe a resonant PWM (pulse-width-modulated) inverter-linked DC-DC converter which uses the high-voltage transformer parasitic LC circuit parameters as resonant components and the high-voltage cable input capacitance as smoothing filter. Theoretical results obtained by computer-aided simulation and experimental results obtained by a test circuit including prototype transformers are illustrated and discussed from a practical point of view. The phase-shift PWM control for adjusting the DC output voltage of the resonant converter is presented. One of the advantages of this converter is minimization of circuit components; this kind of circuit topology can minimize the size and weight of power supply systems and can be applied to the filament heating circuit connected to the cathode of the X-ray tube. >

Power network supplied high-frequency low-pressure discharge lamp operating circuit

Abstract: To reduce network harmonics upon connecting a fluorescent lamp (LP) with aower network rectifier (2) and a push-pull frequency generator (3) and a series resonance circuit (4) to the network, a harmonic filter is connected in the circuit with the fluorescent lamp. The harmonic filter includes two diode pairs (D8, D9; D10, D11) connected in forward current passing direction to the power rectifier (2). Two capacitors (C7, C8) connected to the common junction (M2) between the diodes (D8, D9) of one pair and a center common terminal (M1) between the alternately conducting transistors (T1, T2) of the push-pull frequency generator and an electrode (E1) of the lamp; and an inductance (L2) connected through a blocking capacitor (C9) to a common junction (M4) between the diodes (D10, D11) of the second pair, to provide for pumping of respectively leading and lagging reactive energy into the power network when the current wave of the a-c power supply passes through zero or null and thereby improve the overall wave shape of the power supply system.

Resonance damping apparatus for LC filter of power converter

Abstract: The present invention discloses an apparatus for damping resonance of an LC type low-pass filter provided on the DC input side of a power converter having a DC input terminal. The apparatus comprises an electric circuit connected in parallel to a reactor constituting the LC type low-pass filter. The electric circuit has an impedance which takes a substantially minimum value at a frequency equal to the resonance frequency of the LC type low-pass filter.

Self oscillating power stage for inverted rectifier power supply

Abstract: A self-oscillating inverted rectifier has a series-resonant circuit connected between a load and the selector terminal of an electronically controllable switch, the other terminals of which are connected respectively to d.c. sources of different potential. Phase detection and feedback circuits provide a rectangular control wave for connecting and disconnecting the resonant circuit to each d.c. source only at null transits of the current in the resonant circuit. The feedback circuit includes a control circuit supplied with a regulation voltage, which may be derived from the load, whereby the switch is intermittently prevented from connecting the resonant circuit to energizing d.c. for an integral number of half cycles of the resonant frequency. The load may be a high-frequency electrosurgical device or, more generally, a rectifier circuit providing accurately regulated d.c. power to a variable load.

The development of a thick-film non-contact shaft torque sensor for automotive applications

Abstract: The system described uses a novel thick-film capacitive torque sensor, which is applied to the rotating shaft. The capacitive sensor forms part of a rotating resonant circuit, which is excited across an air gap by means of inductive coupling. Variations in torque cause changes in the resonance frequency of the tuned circuit. The torque may be detected as a change in the resonance frequency, or as a change in referred impedance measured at the exciting coil. The prototype capacitive torque transducer was constructed from flexible printed circuit boards, which were bonded to the shaft. Subsequent sensors have been formed by printing thick-film conductor patterns. This novel approach provides a much simpler method of manufacturing the sensor. Two telemetry systems are discussed, one using a sweep frequency oscillator and one using a bridge circuit. It is shown that for most applications the bridge circuit is preferable.

System for remote information interchange between a portable object and a station

Abstract: The station, in particular a terminal, comprises an oscillator (OS) having a feedback loop (1) and a station inductor element (L10) suitable for conferring a working frequency to the oscillator which varies relative to a rest frequency. The station also includes a station processor connected to the oscillator and capable of processing variations in the working frequency of the oscillator. The portable object, in particular a memory card, includes an electronic circuit which is switchable between an inactive state and an active state in which it sets up a resonant circuit tuned on a frequency which is distinct from the rest frequency while remaining suitable for being coupled inductively with the feedback loop (1) at the rest frequency. The portable object also includes an object processor capable of switching the electronic circuit as a function of the information to be transmitted to the station. The variation in the operating frequency of the oscillator as induced in this way by the switching enables the station processor to deduce the information.