Showing papers on "Negative impedance converter published in 2002"

A technique for power supply harmonic impedance estimation using a controlled voltage disturbance

Abstract: A method for power system impedance estimation is presented. The method employs a power converter to inject a voltage transient onto the supply system. As the technique employs controlled power electronic devices it may be used as a stand alone piece of a portable measurement equipment, or it may be embedded into the functions of an active shunt filter for improved harmonic control. The impedance is estimated through correlation of the measured voltage and current transients. Simulations and experimental results demonstrate the measurement technique is highly accurate and effective.

High-voltage multilevel converter with regeneration capability

Abstract: This paper presents a multilevel converter with regeneration capability. The converter uses several power cells connected in series, each working with reduced voltage and with an active front end at the line side. This paper presents the following: (1) the control method of each cell; (2) the use of phase-shifting techniques to reduce the current and voltage distortion; and (3) criteria to select the connection of the cells. The converter generates almost sinusoidal currents at the load and at the input and works with very high power factor.

Multi-phase converter with balanced currents

Abstract: A multi-phase DC/DC converter having an output voltage and including a plurality of converter channels. Each converter channel includes a converter channel input and a converter channel output. Each converter channel is configured for generating a converter channel current and for adjusting said converter channel current in response to a control signal electrically connected to each converter channel input. A control circuit generates an error signal representative of a comparison of the converter output voltage to a reference voltage. The control circuit includes a plurality of control circuit channels, each of which correspond to a converter channel. Each control circuit channel generates a channel current signal representative of a corresponding converter channel current, and generates a differential channel current signal representative of a comparison of the channel current signal to an average current signal. The average current signal is representative of an overall average current for the converter channels. Each control circuit channel generates a differential error signal representative of a comparison of the error signal to the differential channel current signal. Each control circuit channel includes a pulse width modulator having a ramp input and a control input. The control input is electrically connected to the differential error signal. The pulse width modulator generates the control signal based upon the differential error signal. The control signal is electrically coupled to a corresponding converter channel input. The control circuit generates the average current signal.

Method for regulating an inverter system

Abstract: The invention describes a method of regulating a rectifier inverter system ( 1 ), whereby electrical power is generated and/or supplied via a power source ( 6 ) and is transmitted from at least one d.c.-to-d.c. converter ( 3 ) to an intermediate circuit ( 4 ), from where it is fed via a d.c.-to-a.c. converter ( 5 ) to an alternating voltage supply ( 8 ) and/or delivered to a consumer. The d.c.-to-d.c. converter ( 3 ) is regulated in such a way that a virtually constant current flow is applied from the input of the d.c.-to-d.c. converter ( 3 ), in other words from the power source ( 6 ), to the output of the d.c.-to-d.c. converter ( 3 ), in other words the intermediate circuit ( 4 ), during a pre-settable period irrespective of the power drawn off from the intermediate circuit ( 4 ), whereas during this same period power is drawn off from the intermediate circuit ( 4 ) to feed it to the alternating voltage supply ( 8 ) or deliver it to the consumer. A controller or a control system of the d.c.-to-d.c. converter ( 3 ), in particular a desired value for regulating the current flow through the d.c.-to-d.c. converter ( 3 ), is re-set whenever the period elapses.

Integrated circuit and method of controlling output impedance

Abstract: An integrated circuit ( 100, 200, 300 ) includes a voltage-mode driver circuit having an analog on-chip termination and also having a substantially constant output impedance across an operating range of an output voltage of the voltage-mode driver circuit. The voltage-mode driver circuit also maintains a substantially constant output impedance through voltage transitions to minimize voltage reflections while driving cabling.

Negative ion generator

Abstract: A negative ion generator, which can suppress positive ion generation, permits ready control of a quantity of generated negative ions and permits a size and thickness reduction. The negative ion generator is of an electron emission type in which, for negative ion generation, electrons are emitted into the air by impressing a negative high voltage on a stylus electric discharge electrode. A piezoelectric transformer is used for amplifying a non-rectified drive voltage from a transformer drive circuit. As a result of rectification of the AC high voltage from the piezoelectric transformer, a negative high voltage is obtained, which is impressed on the stylus electric discharge electrode for electron emission therefrom, thereby generating negative ions in the air.

DC-to-DC converter with fast override feedback control and associated methods

Abstract: A DC-to-DC converter includes a pulse width modulation (PWM) circuit cooperating with at least one power switch for supplying power from a source to a load over a range between a lower limit and an upper limit to thereby control an output voltage for the load. The converter may also include a primary feedback control loop cooperating with the PWM circuit for supplying power to the load between the lower and upper limits based upon the output voltage during normal load transient conditions. The converter may also include at least one override feedback control loop cooperating with the PWM circuit for overriding the primary feedback control loop and supplying power to the load at one of the lower and upper limits based upon the output voltage during a corresponding relatively fast load transient condition. Accordingly, relatively fast load transients can be followed by the converter.

Voltage supplying device, and semiconductor device, electro-optical device and electronic instrument using the same

Abstract: A voltage supplying device which supplies a voltage to a load capacitance to finish charging the load capacitance with a predetermined voltage within a predetermined charging period. The voltage supplying device comprises a digital-analogue converter (DAC) and a voltage follower circuit for performing the impedance conversion for a voltage from the DAC and outputting the converted voltage. A first switching element is provided between the output of the voltage follower circuit and the load capacitance. A bypass line is provided for supplying a voltage from the DAC to the load capacitance bypassing the impedance conversion circuit and the first switching element, and a second switching element is provided on the bypass line. In the first period of the charging period, the first switching element is turned on, and the second switching element is turned off, whereby the output of the voltage follower circuit is supplied to the load capacitance. In the second period of the charging period, the first switching element is turned off, and the second switching element is turned on, whereby the output of the DAC is supplied to the load capacitance instead of the output of the voltage follower circuit.

Charger capable of converting multiple power sources

Abstract: A charger includes a direct current (DC) converter and an alternating current (AC) converter. The DC converter includes a DC input port, a conversion circuit, a transmission port for inputting a second voltage, an output port, and a switch for selectively outputting the first voltage or the second voltage. The AC converter has an AC input port, an AC conversion circuit for transforming an AC power source to the second voltage, and a power port corresponding to the transmission port for outputting the second voltage to the transmission port. The DC converter and the AC converter are capable of engaging with each other such that the power port is connected to the transmission port, and the charger can provide power via the output port provided by the AC power source or the DC power source.

A bi-directional DC-DC converter with minimum energy storage elements

Abstract: A proof-of-concept military advanced mobile generator set has been developed. The military generator set uses an internal combustion diesel engine to drive a radial-gap permanent magnet alternator at variable speed. The speed of the engine is determined from a user selectable interface that for a given load and ambient thermal conditions controls the engine to run at its most efficient operating point. The variable frequency, variable voltage produced by the permanent magnet alternator is diode-rectified to a high voltage (/spl sim/400 V) DC link, and an inverter is used to produce selectable frequency, controllable AC voltage. As part of the power electronics for this unit, a 7 kW bi-directional DC-DC converter has also been developed. The converter can charge 24 V batteries that are used to start the internal combustion engine and to power auxiliary low voltage DC loads. Additionally, the bi-directional converter can also draw power from the batteries to help maintain the high voltage DC link during severe load transients. Because of stringent weight and volume requirements for this application, the minimum in energy storage elements (high frequency transformers, capacitors, and inductors) was used. This paper presents a description and experimental analysis of this novel DC-DC converter design.

Medium frequency energy supply for rail vehicles

Abstract: Disclosed is an electronic circuit for the bidirectional conversion of a high input voltage to a direct-current output voltage with indirect coupling, more specifically such a circuit for use in a power supply system for rail vehicles, that is provided with a primary converter, one single common transformer and a secondary converter. The primary converter includes at least three primary converter sections connected in series, the output lines of which are each connected to a respective one of the transformer primary windings.

Method of regulating an output voltage of a power converter by calculating a current value to be applied to an inductor during a time interval immediately following a voltage sensing time interval and varying a duty cycle of a switch during the time interval following the voltage sensing time interval

Abstract: The output voltage of a power converter is regulated by comparing the output voltage to a target output voltage during a first time interval and calculating an inductor current required in a second time interval immediately following the first time interval to increase the output voltage to the target output voltage in the second time interval. The duty cycle of a switch in the power converter is varied to modify the current in the inductor during the second time interval according to the calculated next current and a saturation current of the inductor. In one embodiment the power converter includes a reference resistor. By measuring the voltage across the reference resistor at certain times various parameters, including coil inductance and capacitor capacitance, are calculated. In some embodiments a linear model of the power converter is used.

Dc-dc converter with current control

Abstract: A direct current voltage converter includes a substantially static direct current voltage source (210), an inductor (220); a current-control switch (215) coupled with, and between, the voltage source (210) and the inductor, (220) a step-up switch (230) coupled with the inductor (220), and a current sense device (235) coupled in series with the step-up switch (230) and electrical ground The converter also includes a capacitor (260) for storing converted voltage that is coupled with, and between, electrical ground, and the inductor (220) and the step-up switch (230) through a device (240) for controlling current flow direction The converter further includes a first control circuit (219), which opens and closes the current-control switch based, at least in part, on an electrical current conducted through the current sense device (235), and a second control circuit (250), which opens and closes the step-up switch (230) based, on a voltage potential across the electrical load (270)

Integrated circuit for generating a plurality of direct current (DC) output voltages

Abstract: A cascaded DC-DC converter architecture has an upstream converter stage and a downstream converter stage, which derives its input voltage from the upstream stage. Cascading the two converter stages enables functionality of control and monitoring (including soft start and overcurrent detection) circuitry of the upstream stage to be used for the downstream stage, to reduce chip area, cost, and complexity. A voltage window regulator in the downstream converter ensures that, during shutdown, its output voltage will be maintained within a prescribed window of its regulated output voltage, so that no soft start delay is needed when the second converter stage is turned back on.

Technique for limiting current through a reactive element in a voltage converter

Abstract: A current limiting technique for a voltage converter. A current through a reactive element in a voltage converter is limited. Current from a supply is switched through a reactive element in accordance with a switch control signal for forming a regulated output voltage in a feedback loop. A first signal that is representative of the input current is sensed. A voltage that is representative of the output voltage of the voltage converter is sensed. A second signal that is representative of a difference between the output voltage and a desired voltage is formed. A selected one of the first signal and the second signal is compared to a ramp signal for forming the switch control signal wherein the selected one of the first signal and the second signal is selected according to the relative magnitudes of the first and second signal.

Input sub-ranging converter system for sampling semiconductor temperature sensors

Abstract: A converter system for a temperature sensor includes a programmable current source, a digital-to-analog converter, a summer, and an analog-to-digital converter. The temperature sensor provides a measurement voltage in response to application of a bias current. The programmable current source selectively provides two different currents to the temperature sensor such that the temperature sensor provides two measurement voltages during a given temperature measurement. The digital-to-analog converter (DAC) provides an intermediate voltage that corresponds to an approximation of a voltage between the two voltages. A summer is configured to produce an offset measurement in response to the intermediate voltage and the measurement voltage. The analog-to-digital converter (ADC) receives the offset measurement voltage and produces a conversion code. Offsetting the measurement voltage reduces the dynamic range requirements of the ADC such that substantially a full input range of the ADC is utilized.

Circuit and method for detecting load impedance

Abstract: A device for detecting load impedance having an analog circuit portion for detecting the impedance value of a load, and a digital circuit portion adapted to provide load impedance type information. The analog circuit portion having two power MOS transistors connected in series to each other and between a supply voltage and the ground, and a pair of mirror MOS transistors common-connected with their respective gate terminals to the gate terminals of the power MOS transistors. The digital circuit portion includes a first comparitor to determine whether the output current of an audio amplifier is higher or lower than a threshold value and a second comparitor to determine whether the output voltage of the amplifier is higher than a threshold voltage, a memory to store output signals of the first and second comparitors, and a logic circuit arranged in cascade with the memory to output a load-type indication signal. The device further includes a third comparitor that enables outputting of the load-type indication signal when the output voltage of the audio amplifier crosses a zero threshold to thereby eliminate unwanted noise.

Bidirectional VSC converter with a resonant circuit

Abstract: The invention relates to a VSC-converter for converting direct voltage into auxiliary voltage and vice versa, which comprises a series connection of at least two current valves ( 5, 6 ) arranged between two poles ( 7, 8 ), a positive and a negative, of a direct voltage side of the converter, each current valve comprising several series connected circuits ( 12 ), each of which circuits comprising a semiconductor component ( 13 ) of turn-off type and a rectifying component ( 14 ) connected in anti-parallel therewith, an alternating voltage phase line ( 16 ) being connected to a midpoint ( 15 ), denominated phase output, of the series connection of current valves ( 5, 6 ) between two of said current valves while dividing the series connection into two equal parts. Each of the series connected circuits ( 12 ) of the respective current valve comprises, in order to make possible a good voltage distribution between the semiconductor components ( 13 ) of turn-off type included in the respective current valve, a snubber capacitor ( 17 ) connected in parallel with the semiconductor component ( 13 ) of turn-off type included in the circuit. The converter ( 1 ) further comprises a resonance circuit ( 18 ) for recharging the snubber capacitors ( 17 ) of the current valves.

Dc-dc converter with resonant gate drive

Abstract: A direct current to direct current boost or buck voltage converter in accordance with the invention includes a plurality of switching devices that effect voltage conversion and control current flow direction in the converter. The converter also includes a control circuit for comparing an output voltage of the converter with a reference voltage, where the control circuit produces a comparison signal based on that comparison. A resonant gate-drive circuit, also included in the converter and coupled with the control circuit and the plurality of switching devices, opens and closes the plurality of switches in response to the comparison signal to effect voltage conversion and control current flow direction.

Active voltage level bus switch (or pass gate) translator

Abstract: A bi-direction voltage level translating switch that connects a higher voltage circuit to a lower voltage circuit without using a direction signal disclosed. The drive circuit for the gate of an MOS switch acts to clamp the lower voltage side of the translating switch limiting the lower voltage to a level compatible with the lower voltage circuitry connected to the lower voltage side. A pull up circuit is connected to the higher voltage side of the switch and further defines a threshold lower than the lower voltage. When the signal reaches the threshold the pull up circuit pull the higher voltage side up to the higher voltage. Again the drive on the gate of the switch prevents that higher voltage from reaching the lower voltage side. When the lower voltage side drives, through an on switch, the higher voltage side low, the pull up circuit is designed to be overcome by the lower voltage drive circuitry so that the higher voltage side goes low. When the threshold is reached going low the pull up circuitry is disabled. In a preferred embodiment, the pull up circuit provides a low impedance connection to the higher voltage to quickly drive the higher voltage side high, but the low impedance is active for a given amount of time, wherein the pull up circuitry reverts to a high impedance. The circuit is suitable for operating in virtually all computer systems including networked communications, displays, data bases, and the like.

Offset peak current mode control circuit for multiple-phase power converter

Abstract: An offset peak current mode control circuit is provided for use with a multiple-phase DC-to-DC voltage converter including a plurality of converter modules connected to a common load and having a common input voltage source, a current sensor coupled to a sensing resistor disposed in series between the common input voltage source and the load to derive a current sense signal corresponding to current passing through the sensing resistor, and a voltage error sensor coupled to the load to derive a voltage error signal corresponding to difference between an output voltage of the voltage converter and a reference voltage. When the DC-to-DC voltage converter is operated with a relatively low input voltage or a relatively high duty cycle resulting in an overlap of the current sense signal, the offset peak current mode control circuit utilizes information from the clean (i.e., non-overlapping) portion of the current sense signal, and then stretches the duty cycle applied to an associated voltage converter module so that it extends into the time of the overlapping portion of the current sense signal.

Unregulated electrical converter

Abstract: An AC-DC voltage converter includes input terminals with a series circuit connected between the input terminals. The series circuit includes a switching element and a capacitor. The discharge of the capacitor supplies the output voltage of the converter. A control circuit controls the operation of the switching element so that the conducting state of the switching element is controlled exclusively as a function of the input voltage, while the nonconducting state of the switching element is controlled exclusively as a function of the output voltage. The converter has a good dynamic range and allows accurate measurement of current consumption at the output.

Converter for converting an AC power main voltage to a voltage suitable for driving a lamp

Abstract: An electronic converter converts high-voltage AC power main voltage, such as 120V, 240V or 277V, to a low-voltage suitable for driving a halogen lamp. The converter includes a rectifier circuit, starter circuit, a driver circuit, a current sensing circuit and a transformer circuit with an optional synchronous output rectifier. The current sensing circuit senses an output current of the converter. The sensed current is used to govern pulse-width modulation of the lamp drive voltage, to provide over-voltage protection. Temperature protection can also be provided to reduce drive current when the converter overheats. This enables reliable operation of the converter over an extended temperature range, and reduces the occurrence of converter component failures due to ground faults or overheating.

Comparison of new and conventional low voltage current mirrors

Abstract: A comparison of several architectures of low voltage CMOS current mirrors is presented. The comparison includes: input impedance, output impedance, gain accuracy, frequency response and input and output voltage requirements. Simulations and experimental results of test chips prototypes are shown that are in good agreement with theoretical predictions.

Power supply device for automobile

Abstract: PROBLEM TO BE SOLVED: To provide a power supply device for automobile capable of constructing light and small structure and establishing an enhanced efficiency while the impression of the supply voltage to the prescribed load is secured stably. SOLUTION: The power supply device for automobile includes a DC-DC converter 7, which is driven for boosting the voltage in the case the battery voltage is considered as dropped so that a current feed is made from a battery 1 to a second load 3, and the current feed is made in such a way as skipping the DC-DC converter 7 using a switch means 8 in the case the battery voltage can impress a sufficiently large supply voltage on a second load 3. Thereby a comparatively light and small DC-DC converter 7 can be used, and the loss in power transmission can be reduced. COPYRIGHT: (C)2003,JPO

Sound isolation by piezoelectric polymer films connected with negative capacitance circuits

Abstract: Sound pressure produces strain and polarization in piezoelectric polymer films. The electric charge induced by the polarization in the electrode of the films is introduced to a negative capacitance circuit and the resulting voltage is fed back to the electrode. The field-induced strain cancels the stress-induced strain, leading to the increase of the elastic coefficient of the films. If the capacitance of the circuit is controlled to be equal to that of the film, the elastic coefficient approaches infinity. Using this principle, the sound isolation by piezoelectric polymer films connected with a negative capacitance circuit was undertaken. A PVDF film with a curved plane was located in the middle of an acoustic tube and the transmission loss through the film was determined in the audio frequency range. At any single frequency, the complete isolation of sound was achieved by adjusting the feedback. The precise matching of complex capacitance of the circuit with that of the film was required to obtain the increase of the transmission loss over a broad frequency range.

A high power factor converter topology for switched reluctance motor drives

Abstract: A new converter topology is proposed for driving a switched reluctance motor with unipolar currents. It consists of a front-end single-ended primary inductance converter (SEPIC) and a switch in series with each motor phase. All the switches are ground-referenced, which simplifies their gate drives. The available input voltage can be boosted for better current regulation, which is an advantage for low voltage applications. The converter can be controlled to operate at a high power factor with an AC supply. For low power applications, the converter is designed to operate in the discontinuous conduction mode. In this operation mode, it approximates a voltage follower and the line current follows the line voltage waveform to a certain extent. The improved power factor is achieved without the use of any voltage or current sensors. For higher power levels, multiplier control is used with operation in the continuous conduction mode. The simplicity and reduced parts count of the proposed topology make it an attractive low-cost choice for many variable speed drive applications.

Analog-to-digital conversion circuit having increased conversion speed and high conversion accuracy

Abstract: In an analog-to-digital conversion circuit, the gain of an operational amplification circuit in each of first- to third-stage circuits is two. The reference voltage range of a sub-A/D converter in each of the stages of circuits is set to one-half the reference voltage range of a D/A converter, so that the output voltage range of the D/A converter coincides with the output voltage range of the operational amplification circuit. When the voltage range of the analog input signal is VIN p-p , the full-scale range of the sub-A/D converter is switched to VIN p-p , and the gain of the operational amplification circuit is one. When the voltage range of the analog input signal is VIN p-p /2, the full-scale range of the sub-A/D converter is switched to VIN p-p /2, and the gain of the operational amplification circuit is two.