Showing papers on "Inductor published in 1988"

Ingestible size continuously transmitting temperature monitoring pill

Abstract: A temperature responsive transmitter is disclosed. The transmitter utilizes a unique circuit design that allows encapsulation in an ingestible size capsule. The inventive circuit design uses a one transistor inverting amplifier with a tank circuit forming the link between the transistor's collector and the battery. The tank circuit is tuned to provide a lagging capacitive load which causes the inverting amplifier to oscillate. The tank circuit contains a coil inductor that emits a near field magnetic communications field containing temperature information. The ingestible size temperature pill can be configured in a rechargeable embodiment. In this embodiment the pill uses the inductive coil in the tank circuit as the magnetic pickup to charge a rechargeable nickel cadmium battery.

Steady-state analysis and design of the parallel resonant converter

Abstract: Five basic operating modes of the parallel resonant converter are analyzed. Three of the modes occur when the output filter inductor is removed and the remaining two occur when the filter inductor is large. Closed-form solutions are found for the two most important modes. Analysis results are given graphically so that the designer can use them without lengthy calculation or computer iteration. Switching frequency, peak tank capacitor voltage, and peak tank inductor current are plotted in the output plane. These plots, with a load line superimposed, show how operating point, frequency, and peak stress vary as load conditions change. Use of the output plane plots to minimize component costs is explained. Comparison of the best designs found for the large and zero filter inductance cases shows that removing the filter inductor can reduce both parts count and tank circuit size while peak transistor current remains unchanged. >

Broad-band monolithic microwave active inductor and its application to miniaturized wide-band amplifiers

Abstract: A broadband monolithic microwave active inductor and its characteristics are discussed. The inductor consists of a cascode FET with a feedback resistor, and operates in a much higher frequency range than a spiral inductor. The size is independent of the inductance value. Miniaturized wideband amplifiers in two frequency bands are realized utilizing these active inductors. >

Broad band monolithic microwave active inductor and application to a miniaturized wide band amplifier

Abstract: A broadband monolithic microwave active inductor composed of two FETs and a resistor is proposed. The most significant innovation of the active inductor is considered to be a novel circuit structure which suppresses stray capacitance to yield a much higher-frequency operating range than a spiral inductor. The inductor is small and independent of the inductance value. The FET-oriented configuration allows a denser chip circuitry packing. A 0.1-10-GHz miniaturized wideband amplifier realized using the active inductors is described. >

Zero-voltage-switched multi-resonant converters including the buck and forward type

Abstract: A multi-resonant-switching network that operates under switching conditions that are favorable to both the active switch and the diode that constitute the switch. In a zero-current multi-resonant switch, the resonant circuit is formed in a T-network with resonant inductors in series with the switching devices. In a zero-voltage multi-resonant switch, the resonant circuit is formed in a π-network with resonant capacitors connected in parallel with the switch. In this way, the two networks are dual. During operation of a multi-resonant converter, a multi-resonant switches forms three different resonant circuits depending on whether the active switch and diode are open or closed. This results in operation of the converter with three different resonant stages in one cycle of operation. In practicing the present invention, certain rules are applied to derive a 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, another resonant capacitor is placed in parallel with the rectifying diode, and an inductor is inserted in the loop containing the switch and the diode. This loop can also contain voltage sources and filter or blocking capacitors. Improvement in the operation of ZVS-MRCs is obtained with synchronous rectification which is achieved by replacing rectifying diodes in a DC/DC converter with active devices, called synchronous rectifiers.

A new method to regulate resonant converters

Abstract: A resonant frequency-modulation method is presented as an alternative to the switching frequency-modulation method to regulate resonant converters. A switch-controlled inductor and switch-controlled capacitor, in which switching losses are found to be very low due to zero-current or zero-voltage switching, are developed to do so. A new family of resonant converters that are regulated at a fixed switching frequency is proposed. A steady-state analysis of the Class E resonant converter regulated by a switch-controlled capacitor is presented. Theoretical and experimental results verify the validity of the proposed method. The efficiency measured from a breadboard of 1 MHz, 5 V, 25 W Class E regulated resonant DC-DC converter is up to 83%. >

A new injection method for AC harmonic elimination by active power filter

Abstract: An injection method for an active filter which eliminates the harmonics present in AC lines by injecting PWM harmonic compensating current is proposed. In the proposed method, the active filter produces a pulsewidth modulation (PWM) current that cancels the existing harmonics up to any order completely. To generate such PWM current, both inverter and DC current source is needed. The current source can be replaced by a large inductor without any external power source. This can be achieved by providing the inverter with rectifying capability because the inverter has the same circuit structure as the rectifier. Therefore, the proposed model of PWM injection current includes not only the harmonic components to suppress the existing harmonics up to any order, but also the fundamental one, to raise the inductor current to any desired value. The characteristics of the injection method are investigated through a digital computer simulation. Feasibility is proved by the experimental results. >

Planar inductors on magnetic substrates

Abstract: Using the method of current images, a simple formula is derived that describes the enhancement effect of a thick magnetic substrate of permeability mu on the inductance of planar inductors. It is shown that a maximum of 100% enhancement of the inductance over the corresponding air-core value can be obtained. This occurs in the limit mu >>1, in which case the inductance becomes independent of mu . Previous and new experimental data as well as a finite-element result are found to be in very good agreement with the theoretical result. >

Discharge lamp driving circuit

Abstract: A circuit for operating a discharge lamp at a low frequency AC voltage while repetitively interrupting at a high frequency the voltage component to be applied to the lamp. The circuit includes at least one switching transistor for repetitively interrupting the voltage to be applied to the lamp at the high frequency, for example, 40 KHz so as to allow the use of a light and less bulky inductor as the current limiting conductor to be connected in series with the lamp. A bridge inverter is provided to have at least one pair of switching transistors for alternately reversing a DC voltage to apply the resulting AC voltage to the lamp at the low frequency, for example, 100 Hz low enough to stably operate the lamp without suffering from acoustic resonance. The high frequency component is bypassed through a bypass capacitor connected in parallel with the lamp. By reason of the inverter producing the low frequency AC voltage, the circuit requires all-off period during which the switching transistors of the bridge inverter are simultaneously off for preventing the short circuiting of the power source. An oscillation-inducing inductor is connected in series with the lamp in parallel relation to the bypass capacitor so as to form a series oscillating circuit which causes to flow an alternating oscillating current to the lamp circuit throughout the all-off period. The resulting oscillating lamp current continues for a longer time to thereby retard the deionization of the lamp. Accordingly, the all-off time can be extended to such an extent as to give greater flexibility in designing the circuit which is free from short circuiting of the power source as well as from the increased reignition voltage.

Quasi-resonant current mode static power conversion method and apparatus

Abstract: An inverter (30) has a resonant circuit composed of a parallel connected inductor (46) and capacitor (45) and a filter capacitor (47) connected in series with the inductor which has a capacitance substantially greater than the resonant capacitor. A half bridge or full bridge switching circuit formed of pairs (34, 35) of gate controlled switching devices is connected to a DC power supply (31, 32) and to the resonant circuit and filter capacitor (47) with the switching devices (34, 35) being switched to provide a relatively high frequency, e.g., 20 KHz or higher, resonant current in the resonant circuit. The filter capacitor (47) is of a size such that the high frequency component of the current flowing in the resonant circuit does not result in a substantial voltage at the switching frequency appearing across the filter capacitor (47).

A new three degrees of freedom electromagnetic actuator

Abstract: The design of an electromagnetic actuator rotating around three independent axes is presented. The actuator consists of a spherical armature moving around its center; inside this armature are situated three fixed inductors. When power is supplied, the three phase windings of each inductor develop a moving magnetic field acting along its own plane of symmetry. The spherical armature of the actuator is made of magnetic steel; on the inner face, a thin layer of copper has been fixed. In that way, each inductor and the portion of armature that is in front of it behaves like a linear induction motor. When the inductors are adequately supplied with electricity the armature moves inside a solid angle. The actuator developed by the authors moves inside a cone, with a maximum deviation of +or-30 degrees . To make it work and to have good positioning, the actuator is equipped with sensors that detect the position of the armature. The electric power is supplied by three PWM transistor inverters, one for each inductor. >

Effects of air gaps on winding loss in high-frequency planar magnetics

Abstract: Lumped gaps incur unacceptably high eddy-current loss in small high-frequency magnetic geometries because of their close proximity to the winding. The problem is studied for four simulated inductor structures, using finite-element analysis. It is shown that distribution of the gaps uniformly around the core, which can be realized by using low-permeability magnetic material, reduces the AC-DC resistance ratio of series-connected windings to about two at large conductor width. Measures to reduce the field nonuniformity, such as arranging the series turns in multiple layers so that the winding window has better aspect ratio, further reduce winding loss. Loss reduction due to more uniform field distribution offsets the loss increase due to multilayer arrangement, at least for a small number of turns. >

Dual-permeability core structure for use in high-frequency magnetic components

Abstract: A dual-permeability magnetic core structure is provided for use in small, high-frequency inductors and transformers. The dual-permeability corer encloses a winding window containing planar windings and comprises high-permeability and low-permeability sections positioned to produce a highly uniform, or uniformly varying, magnetic field on the winding surfaces. The dual-permeability core produces low winding losses and a low AC-to-DC resistance ratio. Fabrication of the dual-permeability core involves a method of controlling the permeability of a magnetic material and a method of combining structures of two different permeability values.

Magnetic regenerative braking system

Abstract: The present invention is a regenerative braking system useful in systems having variable kinetic energy such as vehicles. A DC machine having an independently energized field coil includes a rotor mechanically coupled for rotation at a speed proportional to the velocity of the load. During deceleration the armature is coupled to an inductor and rotational energy provided by the load is converted into magnetic energy stored in the magnetic field of the inductor. To store the energy a short is connected across the inductor, which is preferably operating under superconducting conditions. For acceleration this inductor current is applied to the DC machine to produce a torque for moving the load. The phase reversal required for proper direction of torque is preferably achieved by reversing the direction of field current. The rate of energy transfer and thus the rate of acceleration or deceleration is controlled by controlling the magnitude of the field coil current. A preferred embodiment includes a vehicle battery and motor control for powering the DC machine as the prime mover of the system. A control circuit responsive to vehicle speed, accelerator pedal position, brake pedal position, and the amount of current in the inductor controls switches for proper transfer of energy.

Electronic transformers and circuits.

Abstract: Transformer Construction, Materials, and Ratings Rectifier Transformers, and Inductors Rectifier Performance Amplifier Transformers Amplifier Circuits Higher--frequency Transformers Saturable Magnetic Circuits High Voltage Pulse and Video Transformers Pulse Circuits Inverter Transformers Inverter Circuits Other Magnetic Devices Index

Controlled leakage transformer for fluorescent lamp ballast including integral ballasting inductor

Abstract: All the magnetic functions required in a ballast for a fluorescent lamp are integrated in a single, standard magnetic core which provides isolation, voltage step-up, ballasting, power factor correction and cathode heat for multiple lamps operating multiple lamps in an isolated-series configuration. In a three-legged transformer core embodiment, the primary winding is continuously wound on all three legs, while secondary windings are included on two of the legs. Ballasting inductance is provided by winding the primary on the third leg. The number of primary turns N p necessary to avoid saturation of the transformer for any specific input voltage and core material, the number of primary windings N p1 on the secondary legs and the number of primary windings N p2 on the third leg are determined according to the equation 2N p1 =N p -N p2 .

Driver circuit for power transistors

Abstract: A gate driver circuit is provided for push-pull power transistors. Inverse square wave signals are provided to each of the driver circuits for activating the power transistors. The combination of an inductor and diodes provides a delay for activating the corresponding power transistor at a positive transition of the control signal, but do not have a significant delay at the negative transition. This provides protection to prevent the power transistors from being activated concurrently while having lower power loss at high drive frequencies. The control terminal for each power transistor is connected to a voltage clamping circuit to prevent the negative transition from exceeding a predetermined limit.

Recovery circuit for snubber energy in power electronic applications with high switching frequencies

Abstract: A simple, reliable circuit is presented that allows snubber energy to be recovered by using a self-oscillating DC-to-DC converter. The applicability of the circuit is experimentally proved in three different types of power converters for electrical drives. >

Filter switching arrangement for a tuner

Abstract: In a tunable filter including first and second inductors, a varactor diode, and a bandswitching diode connected intermediate the inductors to select the inductor configuration for first and second tuning bands, a capacitor is connected in parallel with the bandswitching diode. When the bandswitching diode is in the high impedance "non-conducting" state, the capacitor is functionally connected with other elements of the tunable filter for purposes such as trapping or tracking. When the bandswitching diode is in the low impedance "non-conducting" state, the capacitance is functionally disconnected from the tunable circuit.

Modeling of quantum series resonant converters-controlled by integral cycle mode

Abstract: Quantum series resonant converters (SRCs), a subset of SRCs operating on optimal conditions, are modeled. It is shown that this type of SRC can be modeled as a buck/boost converter with an equivalent inductor. Operation of SRCs with boost and buck-boost characteristics is proposed. Modeling of these converters is verified through analysis and simulation results. Using these models, the quantum SRCs can be designed to be controlled with advanced closed-loop feedback, with advantages such as low device switching stress, reliable high-frequency operation, and low EMI (electromagnetic interference). >

Fiber-optic multigigabit GaAs MIC front-end circuit with inductor peaking

Abstract: The design and performance of a multigigabit optical front-end circuit are discussed. Inductor peaking is applied to the GaAs MIC preamplifiers and a 3-dB down bandwidth of 6.5 GHz, 15.5-pA/ square root Hz averaged input equivalent noise current density from 10 MHz to 6.5 GHz, and transimpedance gain of 57 dB are achieved. A 3-dB down bandwidth of 6.1 GHz is achieved in an optical front-end circuit with a InGaAs p-i-n photodiode. This performance indicates that the optical front-end circuit with inductor peaking is promising for multigigabit optical receivers. >

Device for reducing the leakage noise of a power converter

Abstract: A device for reducing the leakage noise of a power converter having a rectifier circuit connected to an alternating current power source and an inverter circuit connected to the rectifier circuit has a first noise filter, with a plurality of inductors and capacitors, and which is coupled between the alternating current power source and the rectifier circuit; and a second noise filter, with a plurality of inductors and capacitors, and which is coupled between the rectifier circuit and the inverter circuit.

Saturable inductor and transformer structures for magnetic pulse compression

Abstract: Saturable inductor and transformer for magnetic compression of an electronic pulse, using a continuous electrical conductor looped several times around a tightly packed core of saturable inductor material.

Series resonant inverter with lossless snubber-resetting components

Abstract: A circuit for "resetting" snubbers in a series resonant bridge inverter maintains lossless snubber action during light-load and no-load inverter operation and during operation near resonance Series resonant circuit operation is controlled to be above the resonant frequency to ensure operation at a lagging power factor The snubber-resetting operation is facilitated by a relatively small inductor connected across the output terminals of the series resonant inverter

Low temperature plasma generator with minimal RF emissions

Abstract: A low temperature plasma generator having reduced radio frequency (RF) emissions, and a method for reducing the RF emissions of a plasma generator. A low temperature plasma generator (100) includes a pair of electrodes (150 and 160) that are energized by an RF power supply (138) through a balanced impedance matching network (200). The impedance matching network includes a balun transformer (158), matched variable inductors (222 and 230), a fixed capacitor (240) in parallel with a variable capacitor (244) and a fixed capacitor (242) in parallel with a variable capacitor (246). The RF potential on electrodes (150 and 160) varies sinusoidally between opposite positive and negative values with respect to ground potential, such that the net potential on the two electrodes with respect to ground is always substantially equaol to zero, thus eliminating a glow discharge current and radiation emissions that otherwise are produced by similar prior art low temperature plasma generators.

A complete DC characterization of a constant-frequency, clamped-mode, series-resonant converter

Abstract: The DC behavior of a clamped-mode, series-resonant converter is characterized systematically. Given a circuit operating condition, the converter's model of operation is determined and various circuit parameters are calculated, such as average inductor current (load current), RMS inductor current, peak capacitor voltage, RMS switch currents, average diode currents, switch turn-on currents, and switch turn-off currents. Regions of operations are defined, and various circuit characteristics are defined to facilitate the converter design. >

State-plane analysis of a constant-frequency clamped-mode parallel-resonant converter

Abstract: A novel clamped-mode parallel-resonant converter which operates at a constant frequency and provides a wide output voltage regulation range is proposed and analyzed. Employing graphical state-plane techniques, five circuit operating modes are identified and their mode boundaries defined. Regions for natural and forced commutation of power devices are specified. The DC control-to-output characteristics are derived to facilitate converter design. The predicted operating modes are experimentally verified using a 105 kHz prototype circuit. >

Magnetic head drive circuit

Abstract: A magnetic head drive circuit for driving a coil of the magnetic head performing opto-magnetic recording, is disclosed. According to the present invention, the switching elements are actuated on the basis of driving signals for commutatingly connecting three power sources presenting three different potentials to both ends of a coil of the magnetic head such that the potential difference across both ends of the coil at the time of magnetic field inversion is larger than that at the time of generation of the stationary magnetic field to render the rise time of the current flowing in the coil sufficiently short.

Sintered ferrite body, chip inductor, and composite LC part

Abstract: A ferrite composition comprising ferrite, borosilicate glass, and optionally boron oxide can be fired at a relatively low temperature of up to 950° C. into a sintered body having improved mechanical strength and electromagnetic properties. The sintered ferrite body is used to form a chip inductor. The inductor is combined with a capacitor to form a composite LC part.

High sensitivity magnetic sensor

Abstract: A magnetic sensor is provided for use in detecting an external magnetic field, typically geomagnetism. Pulse or alternating current is applied across a wire or strip-shaped electrically conductive, magnetic body in its longitudinal direction to create an internal magnetic field in the magnetic body. A pick-up winding is wound around the magnetic body. The sensor detects an electric signal developed in the winding as a result of interaction of the internal and external magnetic fields.