Showing papers on "Voltage droop published in 2002"

A novel droop method for converter parallel operation

Abstract: For the converter parallel operation, the current sharing between modules is important for the reliability of the system. Among several current sharing schemes, the droop method needs no interconnection between modules, which implies true redundancy. But the droop method has poor voltage regulation and poor current sharing characteristics. In this paper, a novel droop method is proposed for the converter parallel operation, which adaptively controls the reference voltage of each module. This greatly improves the output voltage regulation and the current sharing of the conventional droop method. The analysis of the proposed method and design procedure are provided and experimental results verify the excellent performance of the proposed method.

Compensation of distribution system voltage using DVR

Abstract: A dynamic voltage restorer (DVR) is a power-electronic controller that can protect sensitive loads from disturbances in the supply system. In this paper, it is demonstrated that this device can tightly regulate the voltage at the load terminal against imbalance or harmonic in the source side. The behavior of the device is studied through steady-state analysis, and limits to achievable performance are found. This analysis is extended to the study of transient operation where the generation of the reference voltage of the DVR is discussed. Once the reference signals are generated, they are tracked using a switching band scheme. A suitable structure in which the DVR is realized by voltage-source inverters (VSIs) is also discussed. Particular emphasis to the rating of this device is provided. Extensive simulation results are included to illustrate the operating principles of a DVR.

Multi-phase switching regulator

Abstract: An N-phase switching voltage regulator includes N current sensing elements (14, 16, 23, 24) which carry respective phase currents. The voltages present at the switch node sides of the sensing elements are summed and presented to an amplifier (28) which also receives the regulator's output voltage, to produce an output which is proportional to the regulator's total output current Iout. The invention also provides a means for direct insertion of total inductor output current information into a regulator's voltage-mode control loop, to provide active voltage positioning (AVP) for the output voltage. A voltage based on total inductor output current is summed with the regulator's reference voltage; this sum and Vout are applied to the voltage control error amplifier (114), the output of which is processed to operate the regulator's switches (100, 102). This enables the regulator's ouput to have a desired droop impedance and to provide AVP of Vout as a function of total filtered inductor output current I?out(fltr)?.

Using supercapacitors to improve battery performance

Abstract: There are many loads that create current pulses yet require a small voltage droop. This can be very demanding on battery sources. The battery voltage and current can be filtered with a capacitor. The capacitor must have sufficient energy storage to deliver the current pulse for the required time, and its equivalent series resistance (ESR) must be small enough to minimise the voltage droop. Supercapacitors meet these requirements. This paper examines performance improvement when a supercapacitor is used with a battery.

Voltage recovery after unbalanced and balanced voltage dips in three-phase systems

Abstract: This paper studies the recovery of the voltage after a voltage dip due to a fault in a three-phase system. The instant of voltage recovery corresponds to the instant of fault clearing. For single-phase and phase-to-phase faults, a single point-on-wave of voltage recovery can be defined. For two-phase-to-ground and three-phase faults, the recovery takes place in two or three steps. The voltage recovery is described in a systematic way by using a classification of three-phase unbalanced voltage dips. The voltage recovery needs to be modeled correctly for studies of equipment immunity against voltage dips.

Boost-buck cascade converter for pulsating loads

Abstract: A power converter including a first stage, a reservoir capacitor and a second stage. The first stage converts the voltage of a primary energy source, such as a battery, to a voltage on the reservoir capacitor, which stores a large amount of energy in the form of a voltage substantially larger than the voltage of the primary energy source. The second stage converts the voltage on the reservoir capacitor to a substantially constant voltage for a load device that demands current having the form of large, short, current pulses. The cascaded converter prevents the pulsating load currents of the load device, such as a GSM power amplifier, from causing a severe voltage loss at the battery. This increases the power available from the battery and reduces loses from the internal resistance of the battery.

Static memory cell having independent data holding voltage

Abstract: A static memory cell, composed of cross-coupled MOS transistors having a relatively high threshold voltage, is equipped with MOS transistors for controlling the power supply line voltage of the memory cell. To permit the voltage difference between two data storage nodes in the inactivated memory cell to exceed the voltage difference between the two nodes when write data is applied from a data line pair DL and /DL to the two nodes in the activated memory cell, the power supply line voltage control transistors are turned on to apply a high voltage VCH to the power supply lines after the word line voltage is turned off. The data holding voltage in the memory cell can be activated to a high voltage independent of the data line voltage, and the data holding voltage can be dynamically set so that read and write operations can be performed at high speed with low power consumption.

Voltage mode differential driver and method

Abstract: A differential driver includes a switching module and first and second voltage controlled voltage sources. The switching module has a plurality of switches each controlled by an input signal, a first voltage input and a second voltage input, and a signal output. The first voltage controlled voltage source is connected to the first voltage input. The first voltage controlled voltage source has a low impedance. The second voltage controlled voltage source is connected to the second voltage input. The second voltage controlled voltage source also has a low impedance. The switching circuit outputs an output signal having an output voltage and current controlled by the first and second voltage controlled voltage sources. The output signal is based upon the input signal.

LED lamp apparatus for vehicles

Abstract: In an LED unit, all of eight LEDs are connected in series. The voltage of a power supply, that is, a battery of a vehicle, 12 V, is insufficient for the eight LEDs. To cope with this, a boosting circuit is provided within the control unit to boost the voltage to about 16 V which is then applied to the eight LEDs. The front end of the LED unit is connected to a constant-current circuit, and a voltage detection circuit is provided near and connected to this constant-current circuit for detecting the voltage applied to the constant-current circuit. The voltage detected by the voltage detection circuit is compared with a reference voltage drawn from the power supply, is amplified in an amplifier, and is input as a boosting control signal into the boosting circuit. The boosting control signal is output so as to regulate the boosted voltage in such a manner that the voltage detected in the voltage detection circuit is a lowest possible voltage.

Dual-output direct current voltage converter

Abstract: A step-down switching voltage regulator with a push-pull output stage is adapted to provide a voltage converter with an auxiliary voltage rail that supplies an auxiliary voltage that is higher than the input supply voltage. The push-pull output stage of the step-down voltage regulator is used to drive a charge pump voltage-doubler circuit. In this way, a single integrated topology provides a regulated low voltage output as well as an auxiliary high voltage output. The circuit topology enables a low component count resulting in lower component cost and smaller physical size.

Internal high voltage generation circuit capable of stably generating internal high voltage and circuit element therefor

Abstract: In order to stably generate a high voltage of a prescribed level, a Vpp detection circuit which is activated in response to an activation signal for comparing the high voltage with a reference voltage is forcibly brought into an active state for a prescribed period under control of an initial control circuit.

Parallel operation of inverters for distributed photovoltaic power supply system

Abstract: This paper proposes a control technique for operating two or more single phase inverter modules in parallel with no auxiliary interconnections. In the proposed parallel inverter system, all of the modules have the same circuit configuration, and each module includes an inner current loop and an outer voltage loop controls. With power sharing control, load sharing can be automatically achieved and the output current of each inverter can be accurately limited to its maximum rating. This technique uses frequency and fundamental voltage droop to allow all independent inverters to share the load in proportion to their capacities. From the simulation and experiment results, the proposed control for PVS inverters is verified.

Voltage versus VAr/power factor regulation on synchronous generators

Abstract: When paralleled to the utility bus, synchronous generators can be controlled using either terminal voltage or VAr/power factor control. Selection is dependent upon the size of the generator and the stiffness of the connecting utility bus. For large generators where the kVA is significant, these machines are usually terminal voltage regulated and dictate the system's bus voltage. When smaller terminal voltage regulated generators are synchronized to a stiff utility bus, the system voltage will not change as the smaller generator shares reactive loading. However, if the system voltage changes significantly, the smaller generator, with its continuous acting terminal voltage regulator, will attempt to maintain the voltage set point. As the voltage regulator follows its characteristic curve, it may cause either over or under excitation of the smaller generator. Excessive system voltage may cause a small generator to lose synchronizing torque, while low system voltage may cause excessive heating on the generator or excessive overcurrent operation of the excitation system. Maintaining a constant reactive load on the smaller generating unit can reduce the generator field current variations and, thus, reduce the maintenance of the collector rings and brushes. This paper illustrates the effect of changing system bus voltage on small generators utilizing voltage versus VAr/power factor regulation.

Dual loop regulator

Abstract: A dual loop regulator is configured for improved regulation of a supply voltage for a dynamic load based on the magnitude of changes in the load voltage. An exemplary dual loop regulator comprises a primary voltage regulator configured within a linear loop and a secondary voltage regulator configured within a wideband, non-linear loop. The primary voltage regulator is configured for providing a well-controlled, regulated output voltage to the dynamic load, and for addressing small changes in the output voltage. The secondary voltage regulator is configured for sensing undervoltage and overvoltage conditions at the dynamic load, and for addressing changes greater than a predetermined threshold voltage. To facilitate loop stability, secondary voltage regulator can be configured within the wideband, non-linear loop to have a small gain for small changes, a larger gain for large changes, and/or a substantially finite storage capability such that any large signal oscillations will not be sustained.

Embedded voltage regulator and active transient control device in probe head for improved power delivery and method

Abstract: A method and apparatus for making a probe head that has reduced voltage droop and improved transient response. One embodiment a cable providing a plurality of signal conductors and a plurality of power conductors including a first power conductor and a second power conductor, a probe head wired to the cable, a plurality of electrical contacts including a first electrical contact and a second electrical contact, wherein each one of the plurality of electrical contacts is fixed to the probe head and wherein the first power conductor is connected to the first electrical contact, and a first regulatory device physically residing in the probe head and wired between the second power conductor and the first electrical contact. In some embodiments, the first regulatory device includes an active transient control device that senses an output voltage and sources or sinks an appropriate supplemental amount of current to improve transient response.

Semiconductor integrated circuit device capable of externally monitoring internal voltage

Abstract: A test on a desired internal voltage is easily and accurately conducted without increasing current dissipation or the number of pads. A driving circuit receiving a reference voltage from a reference voltage generating circuit has a high input impedance and low output impedance, and generates a voltage substantially at the same voltage level as the reference voltage received, and transmits the generated voltage to a pad with a current driving capability larger than the driving current capability of the reference voltage generating circuit.

Cancellation of load regulation in low drop-out regulators

Abstract: A method for cancelling load regulation, based on level shifting the reference, is proposed. In this architecture, the load current is monitored, sensed, and used to dynamically adapt the effective value of the reference voltage. The proposed architecture reduced a 2.5% load regulation droop to a mere 0.2%, without compromising system stability.

Determination of Steady-State Voltage Stability Limit Using P-Q Curve

Abstract: P -V and Q - V curves are commonly used to determine the steady state voltage stability limit of a power system. In this letter, a new method of determining the voltage stability limit using the P -Q curve is presented. The boundary of the voltage stability region is first determined and then presented in the P -Q plane. For a given operating point, the voltage stability margin can easily be determined from the stability boundary in the P -Q plane. The proposed method of determining the voltage stability limit was tested on a simple system and very interesting results were found.

Method of analyzing integrated circuit power distribution in chips containing voltage islands

Abstract: A method of analyzing the power distribution in a chip containing one or more voltage islands, each voltage island having a power distribution network connected to a chip-level power distribution network by one or more voltage translation interface circuits. The method comprising: analyzing the voltage-island power distribution networks independently of the chip-level power distribution network to obtain voltage translation interface circuit currents; using the voltage translation interface circuit currents as input to a model of the chip-level power distribution network to obtain voltage translation interface circuit input voltages; and calculating voltage translation interface circuit output voltages based on the voltage translation interface circuit input voltages, the voltage translation interface circuit currents, and current-voltage characteristics of the voltage translation interface circuits.

Multi-level non-volatile semiconductor memory device with verify voltages having a smart temperature coefficient

Abstract: A multi-level non-volatile semiconductor memory device includes a memory cell, a reference voltage generator and a level shifter. The reference voltage generator includes a band gap reference circuit and MOS transistors to switch both of a potential level and temperature coefficient of an output voltage. The level shifter multiplying and dividing the potential level of the output voltage, and generating a first verify voltage applied to the gate of the memory cell in order to verify whether the memory cell has the threshold voltage higher than the first verify voltage, and a second verify voltage applied to the gate of the memory cell in order to verify whether the memory cell has the threshold voltage higher than the second verify voltage, the first verify voltage being different from the second verify voltage, a temperature coefficient of the first voltage being almost the same as that of the second voltage.

A method for resetting a state of charge of a battery of a hybrid electric vehicle

Abstract: A method for resetting a state of charge of a battery for a hybrid electric vehicle comprises: determining whether a discharge current of the battery is greater than a predetermined discharge current; determining whether a minimum voltage module has changed, if the discharge current of the battery is greater than the predetermined discharge current; determining whether a theoretical discharge voltage is greater than a voltage of the minimum voltage module, if the minimum voltage module has changed; determining whether the theoretical discharge voltage remains greater than the voltage of the minimum voltage module for a predetermined period of time, if the theoretical discharge voltage is greater than the voltage of the minimum voltage module; and setting a state of charge of the battery as a very low state, if the theoretical discharge voltage remains greater than the voltage of the minimum voltage module for the predetermined period of time.

Apparatus and method for converting voltage and computer-readable recording medium recording program for making computer execute control of voltage conversion

Abstract: PROBLEM TO BE SOLVED: To provide an apparatus for converting a voltage for converting a DC voltage into an output voltage so that the output voltage becomes a voltage command value, even when a boosted output voltage is changed. SOLUTION: A control unit 30 receives the output voltage V2 of a boost converter 12 from a voltage sensor 13, calculates errors in the voltage command from the voltage V2, and regulates a PI control gain (proportionality gain and integration gain), in response to the calculated mistake. The unit 30 feedback controls by using the regulated PI control gain, and the converter 12 converts the DC voltage output from a DC current power source B into the voltage V2 so that the voltage V2 becomes the voltage command. COPYRIGHT: (C)2004,JPO

Analysis and control of DSTATCOM for a line voltage regulation

Abstract: This paper describes a modeling and AC voltage direct control techniques of distribution static synchronous compensator (DSTATCOM) using EMTDC/PSCAD package. Moreover, a model of a three-phase four-wire real distribution system is presented and applied to a model of a DSTATCOM using EMTDC. Using AC voltage direct control, low harmonics and offset in the voltage as well as fast dynamic responses are achieved. The derived simulations are tried to verify the result of this paper.

Display apparatus and power supply device for displaying

Abstract: A power supply device for displaying includes a set register for setting an amplitude and voltage level of a driving voltage for a common electrode and an amplitude and voltage level of a non-selecting period voltage for a scan line, an amplitude reference generating circuit for generating an amplitude reference voltage for the driving voltage of the common electrode and for the non-selecting period voltage of the scan line according to a set value, a VcomH reference generating circuit and a VcomL generating circuit for A.C. driving the common electrode with an amplitude and voltage level determined by the amplitude reference voltage and set value, a VgoffH generating circuit and a VgoffL reference generating circuit for generating the non-selecting period voltage of the scan line with an amplitude and voltage level determined by the amplitude reference voltage and set value.

Control and analysis of a new dynamic voltage restorer circuit topology for mitigating long duration voltage sags

Abstract: Highly automated production processes are particularly susceptible to voltage disturbances in the power system. Series compensation in the form of dynamic voltage restorer (DVR) is used to mitigate these voltage disturbances. The compensation capability of a particular DVR topology depends on its voltage injection ability and maximum energy storage. This paper presents a new DVR circuit topology which has the ability to mitigate long duration voltage sags with comparatively small energy storage capacitors. The proposed DVR is equipped with a line-side current forced reversible rectifier that helps to maintain the DC-link voltage under voltage sag conditions. A closed loop controller that consists of an inner current loop and an outer voltage loop has been incorporated into the DVR inverter to maintain the load voltage at a desired level. Simulation and experimental results are presented to demonstrate the efficacy of proposed DVR multiloop controller for various voltage sags.

Efficient charge pump capable of high voltage operation

Abstract: A high voltage integrated circuit operable in a system having a low voltage reference, a high voltage reference, and a ground, for providing an output voltage higher than the high voltage reference. The integrated circuit includes a high voltage ground reference circuit, operable to provide a high voltage ground reference node. Also included is an oscillator, operable to provide a clock signal, the oscillator being connected to the high voltage reference and to the high voltage ground reference node. An isolated charge pump circuit is provided, operable to generate the output voltage and isolated in the integrated circuit from other circuitry.

Output driver circuit for controlling up-slew rate and down-slew rate independently and up-driving strength and down-driving strength independently

Abstract: An output driver circuit includes a push-pull driver for driving an output signal of a semiconductor device to one of two voltage levels corresponding to a determined data state. The push-pull driver includes a pull-up driving circuit for driving the output signal toward a first voltage level when the data state is logic “high,” and a pull-down driving circuit for driving the output signal to a second voltage level when the data state is “low.” The strength with which the pull-up driving circuit drives the voltage level of the output signal toward the first output voltage level can be controlled independently of the strength with which the pull-down driving circuit drives the voltage level of the output signal toward the second output voltage level. The rate at which the pull-up driving circuit drives the output signal voltage level from a “low” data state to a “high” data state can also be controlled independently of the rate at which the pull-down driving circuit drives the output signal voltage level from the “high” data state to the “low” data state.

Bandgap reference voltage circuit

Abstract: A bandgap reference voltage circuit includes a constant-current circuit, a reference voltage output circuit that generates a reference voltage according to the constant current, a power supply voltage detection circuit, and a start-up output circuit. The start-up output circuit supplies a starting potential to a node in the constant-current circuit until the power supply voltage detection circuit detects that the power supply has reached a voltage sufficient for the constant-current circuit to maintain operation. The power supply voltage detection circuit has circuit elements analogous to the circuit elements in the constant-current circuit that determine this voltage, enabling the start-up operation to be carried out and ended reliably. The start-up output circuit preferably includes a low-impedance path from the power supply to a node controlling supply of the starting potential, so that power-supply noise does not trigger unwanted output of the starting potential after the start-up operation has ended.

Protection device for protecting a voltage source and a load supplied thereby

Abstract: A device for protecting a voltage source and a load supplied with power by the voltage source, comprises a switching element interposed between the voltage source and the load and is associated with a current limiting circuit including a measuring unit for measuring the current provided by the source and a control unit for controlling the switching element so as to prevent the current from exceeding a predetermined current threshold, and a voltage limiting circuit adapted to control the switching element so as to prevent the voltage supplied to the load from exceeding a predetermined voltage threshold.