Showing papers on "Voltage droop published in 2003"

DC bus voltage control for a distributed power system

Abstract: This paper addresses voltage control of distributed DC power systems. DC power systems have been discussed as a result of the introduction of renewable, small-scale power generation units. Also, telecommunication power systems featuring UPS properties might benefit from a broader introduction of DC power systems. Droop control is utilized to distribute the load between the source converters. In order to make the loading of the source converters equal, in per unit, the voltage control algorithm for each converter has to be designed to act similar. The DC side capacitor of each converter, needed for filtering, is also determined as a consequence. The root locus is investigated for varying DC bus impedance. It is found that the risk of entering converter over-modulation is a stronger limitation than stability, at least for reasonable DC bus cable parameters. The stationary and dynamic properties during load variations are also investigated.

Control of small distributed energy resources

Abstract: A method of controlling the output inverter of a microsource in a distributed energy resource system is disclosed. Embodiments of the invention include using unit or zone power controllers that reduce the operating frequency of the inverter to increase its unit output power. Preferred embodiments includes methods wherein the inverter reaches maximum output power and minimum operating frequency at the same time, and further comprising using a voltage controller implementing a voltage vs. reactive current droop. Other aspects of this embodiment relate to an inverter that implements such methods, and a microsource containing such an inverter. These methods can be extended to control inverters in a plurality of microsources, organized in a single zone or in a plurality of zones.

DC Bus Voltage Control for a Distributed Power System

Abstract: This paper addresses voltage control of distributed dc power systems. DC power systems have been discussed as a re- sult of the introduction of renewable, small-scale power generation units. Also, telecommunication power systems featuring UPS prop- erties might benefit from a broader introduction of dc power sys- tems. Droop control is utilized to distribute the load between the source converters. In order to make the loading of the source con- verters equal, in per unit, the voltage control algorithm for each converter has to be designed to act similar. The dc side capac- itor of each converter, needed for filtering, is also determined as a consequence. The root locus is investigated for varying dc bus impedance. It is found that the risk of entering converter over-mod- ulation is a stronger limitation than stability, at least for reasonable dc bus cable parameters. The stationary and dynamic properties during load variations are also investigated. The paper starts with an overview of the simulation model. Then the dc bus voltage controller utilized in the analysis is introduced. The simulation model parameters are given and the controller parameters are discussed. The root locus dependency

Apparatus and method for a sense amplifier circuit that samples and holds a reference voltage

Abstract: A sense amplifier circuit. Specifically, a sample and hold sense amplifier circuit that is capable of sampling and holding a reference voltage comprises a reference voltage sampler circuit coupled to a cross-coupled inverter latch. The reference voltage sampler circuit is coupled to a bitline associated with a memory cell. The reference voltage is sampled from a precharge voltage taken off the bitline, and is used to read a state on a memory cell. The cross-coupled inverter latch is also coupled to the bitline, and is used for amplifying a voltage difference between an output voltage from the cross-coupled inverter latch and the reference voltage. The output voltage is based on a static bitline voltage from the bitline.

Modular and reconfigurable rapid battery charger

Abstract: The battery charger is modular and reconfigurable. It includes charging modular power stages that are configured to receive an alternating current (AC) input and provide a direct current (DC) output for charging a battery. These modular power stages include an inverter coupled to a rectifier circuit that outputs a battery charging current. The modular power stages can also each include a current mode controller coupled to the output of the rectifier circuit and configured to provide a current control signal for the modular power stage, a voltage mode controller coupled to the output of the rectifier circuit and configured to provide a voltage control signal for the modular power stage, and a droop sharing control and configured to ensure current sharing between a plurality of modular power stages under constant voltage operation. A system controller is configured to interface with the modular power stages.

Optimal design of the active droop control method for the transient response

Abstract: Use of the active droop control method is a popular way to achieve adaptive voltage position (AVP) for the voltage regulator (VR). This paper discusses the small-signal model of the active droop control method, which is shown to be a two-loop feedback control system. The compensator design impacts both the current and voltage loops, making the design complicated. An optimal design method is proposed in order to achieve equal crossover frequencies for the two loops so that constant output impedance is realized in the VR. Simulation and experimental results prove the good VR transient response and high efficiency.

On-die droop detector for analog sensing of power supply noise

Abstract: Understanding the supply fluctuations of various frequency harmonics is essential to maximizing microprocessor performance. Conventional methods used for analog validation of the power delivery system fall short in one or more of: a) Measurement accuracy in both frequency and time domains, especially for very high frequency noise caused by large di/dt events. The multi-GHz power supply noise attenuates very quickly away from the die. Conventional approaches of measuring the noise at the pins of the package or at the die using capacitive probes are not accurate for multi-GHz clocks. For this reason, the observability of high frequency on die noise has been very tricky. b) Implementation, e.g. delivery of analog references to multiple areas across a "noisy" die, and compactness/modularity of the measurement units. c) Automation to enable a timely volume of measurements. The efficiency of the measurements is key to correlating a particular speed path to poser supply noise. To address the above issues this paper presents an On-Die Droop Detector (ODDD), a scaleable IC solution implemented and validated on a 90 nm process, for analog sensing of differential high bandwidth supply noise.

Primary-side regulated pulse width modulation controller with improved load regulation

Abstract: The present invention provides a primary-side regulated PWM controller with improved load regulation. In every PWM cycle, a built-in feedback voltage samples and holds a flyback voltage from the auxiliary winding of the transformer via a sampling switch and generates a feedback voltage accordingly. A bias current sink pulls a bias current that is proportional to the feedback voltage. Via a detection resistor, the bias current will produce a voltage drop to compensate the voltage drop of an output rectifying diode as the output load changes. According to the present invention, the bias current can enable the PWM controller to regulate the output voltage very precisely without using a secondary feedback circuit.

Multiple output charge pump

Abstract: A single mode buck/boost charge pump has multiple outputs and is adapted to power a plurality of separate loads, such as light emitting diodes, in a highly efficient manner. The multiple outputs have different voltages. The output current or voltage of at least one of the multiple outputs is regulated by a feedback circuit. The feedback circuit provides a control signal based on a comparison of a reference voltage with a feedback voltage. The feedback voltage is proportional to an output voltage when the charge pump is configured to regulate the output voltage. Alternately, the feedback voltage is a sense voltage across a sense resistor connected in series with a load when the charge pump is configured to regulate output current provided to the load.

Dual voltage architecture for automotive electrical systems

Abstract: A dual voltage automotive electrical system includes a generator for generating a first nominal voltage on a first voltage bus and a bi-directional DC/DC converter for converting the first nominal voltage to a second nominal voltage on a second voltage bus, the second nominal voltage being lower than said first nominal voltage. A battery is coupled to the first voltage bus and selectably coupled to the second voltage bus, and is capable of supplying power to loads on both the first voltage bus and the second voltage bus.

Apparatus and method for a voltage booster with improved voltage regulator efficiency

Abstract: A power management system includes a voltage booster in combination with a voltage regulator to provide a regulated output voltage. The voltage provided to the voltage regulator is used to selectively enable/disable the doubling functionality of the voltage booster to increase power conversion efficiency.

An approach to connect ultracapacitor to fuel cell powered electric vehicle and emulating fuel cell electrical characteristics using switched mode converter

Abstract: Future generation automobiles are being developed on fuel cell as the principal source of power generation in automobiles. Automobiles have fast changing load requirements like acceleration or sudden uphill, thus drastically increasing load torque. Fuel cell cannot respond to these fast changing load due to it's slow dynamic response. A solution is to provide the additional energy required by increased load with secondary source of energy like ultracapacitor till fuel cell responds to the increased load current. This paper proposes a new approach to interface ultracapacitor with fuel cell as secondary source of energy using bi-directional synchronous buck converter. A novel scheme to control fuel cell terminal voltage is presented. This control scheme prevents any substantial droop in fuel cell terminal voltage during sudden load change or disturbance. The whole system with fuel cell model was simulated in SIMULINK for step change in load current. Simulation results show gradual transformation of fuel cell terminal voltage from initial steady state to final steady state with ultracapacitor providing energy during transients, hence avoiding the characteristic fuel cell voltage droop. This paper also proposes a novel method to emulate steady and dynamic electrical characteristics of fuel cell using DSP controlled buck converter.

Variable charge pump circuit with dynamic load

Abstract: A variable charge pump circuit (300) uses a plurality of selectable loads (322, 326, 330; Figs. 5A-5B) to minimize the voltage ripples of the pumped output (334) by selecting the appropriate load for a preselected pump voltage (Vout). The charge pump circuit also compares the pump voltage to a reference voltage (Vref) to shut down the variable charge pump circuit if the pump 10 voltage is larger than the reference voltage. The charge pump circuit also compares the maximum voltage output to the reference voltage to monitor whether the maximum ripple on voltage output is larger than the reference voltage. The charge pump circuit comprises one or more stages (306, 310; 308, 312) operable to receive a supply voltage (Vcc) and generate one or more pump voltages, a plurality of loads (322, 326, 330) each associated with a specific pump voltage, and a load selector means (320, 324, 328) coupled to the output pump and to the plurality of loads for selecting a load associated with a specific pump voltage.

A low voltage to high voltage level shifter circuit for MEMS application

Abstract: High voltage (>15 V) drivers are integrated into the VLSI chip for MEMS application with the development of SOC technology. The pre-driver circuit, which generates the pull-up and pull-down signal, is mainly a voltage level shifter circuit. It converts the low voltage control signal to high voltage control signal. Conventional voltage level shifter circuit using high voltage NMOS and high voltage PMOS operates well on 0.8 /spl mu/m process. However, with the continuous process shrinking, conventional voltage level shifter circuit is not suitable for high voltage power supply due to the reduced breakdown voltage of the high voltage devices. Although stacked high voltage devices can be applied to solve this issue, the circuit will have DC leakage current and the internal high voltage swing problem. This paper describes a new low voltage to high voltage converter circuit. By using all the low voltage devices, the DC leakage current and the high voltage swing node have been eliminated. This circuit is fabricated in 0.35 SOI process. Both simulation and test results validate its operations for controlling high voltage drivers.

Hybrid control of multiple inverters in an island-mode distribution system

Abstract: Inverter-interfaced distributed generation offers the possibility of introducing power quality functions such as suppression of harmonic distortion. However, the traditional voltage- and frequency-droop methods of achieving load sharing work on average values and do not address waveform quality. This paper proposes a hybrid scheme for an island-mode system with many inverters. Inverters in close proximity operate in master-salve mode whereas load sharing between distant groups uses frequency droop. Communication between inverters is used where it can improve performance but not where such links are impractical. The master inverter uses repetitive voltage control at the common node to suppress harmonic distortion. Slave inverters within a group also use repetitive control but in current mode. The performance has been assessed through simulation.

Microprocessor-based hand-held electrical-testing system and method

Abstract: The present invention provides methods and systems for testing voltage drops in positive and negative legs of an electrical system and for determining maximal current capacity of the electrical system based on the measured voltage drops. This is accomplished by connecting load leads of a testing unit at a starter or alternator of the electrical system, and connecting voltage leads of the testing unit at a battery of the electrical system. A load of known resistance is applied and a voltage at the load is measured. Voltage drops at the positive and negative legs of the electrical system are determined, based at least in part on the voltage at the load. A maximum current capacity of the electrical system is calculated based on the determined voltage drops.

Output voltage compensating circuit and method for a floating gate reference voltage generator

Abstract: An apparatus and method is provided for adjusting a reference voltage at an output terminal of a floating gate reference voltage generator circuit in order to improve the accuracy of the reference voltage at an input terminal of a load circuit. The apparatus and method compensates for the voltage drop produced between the output terminal of the reference voltage generator circuit and the input terminal of the load circuit, and includes a capacitor for capacitively coupling the voltage at the input terminal of said load circuit to a floating gate, and a differential amplifier operatively coupled to the floating gate which acts in response to the capacitively coupled load circuit input voltage to adjust the voltage at the output terminal such that the voltage at the input terminal of the load circuit becomes equal to the reference voltage.

Altering operating frequency and voltage set point of a circuit in response to the operating temperature and instantaneous operating voltage of the circuit

Abstract: Setting the clock frequency provided to a load circuit as function of the operating temperature and supply voltage of the load circuit, and setting the supply voltage as a function of the operating temperature of the load circuit. The load circuit can be safely operated above the frequency which would be the limit if the load circuit were operating at the maximum test temperature. At the given operating temperature, the supply voltage can be raised to permit even higher frequency operation, or lowered to reduce power.

High precision charge pump regulation

Abstract: A method for high precision charge pump regulation. The method of one embodiment comprises comparing an output feedback voltage with a reference voltage to determine whether the output feedback voltage is greater than or less than the reference voltage. In response to the comparison, either increasing a frequency for a clock signal if the output feedback voltage is less than the reference voltage, decreasing the frequency for the clock signal if the output feedback voltage is greater than the reference voltage; or disabling the clock signal if the output feedback voltage is much greater than the reference voltage. A pumped voltage is generated in response to changes to the clock signal.

Display device and controlling method thereof

Abstract: A conventional setting voltage was a value with an estimated margin of a characteristic change of a light emitting element. Therefore, a voltage between the source and drain of a driver transistor Vds had to be set high (Vds > Vgs - VTh + a). This caused high heat generation and power consumption because a voltage applied to the light emitting element. The invention is characterized by feedbacking a change in a current value in accordance with the deterioration of a light emitting element and a power source voltage controller which modifies a setting voltage. Namely, according to the invention, the setting voltage is to be set in the vicinity of the boundary (critical part) between a saturation region and a linear region, and a voltage margin for the deterioration is not required particularly for an initial setting voltage.

Display driving device and display using the same

Abstract: A display driving device includes: a tone voltage generating circuit generating as many standard voltages as tones; and a DA converter circuit selecting one of the standard voltages in accordance with display data and outputting the selected standard voltage, and applies a tone display voltage to data signal lines of an active matrix scheme display panel. In the tone voltage generating circuit are there provided: a resistance dividing circuit generating as many standard voltages as tones, the standard voltages having voltage values between an upper limit voltage and a lower limit voltage; and an adjusting circuit generating the upper limit voltage and the lower limit voltage. A reference voltage regulated by an electronic volume control provided externally to the tone voltage generating circuit is supplied to the adjusting circuit, and both the upper limit voltage and the lower limit voltage are varied in accordance with the reference voltage. This makes it possible to provide a display driving device, as well as a display using it, which readily allows for changes in γ characteristics in accordance with the characteristics of the liquid crystal material and the liquid crystal panel without additional manufacturing cost.

Voltage-glitch detection device and method for securing integrated circuit device from voltage glitch attack

Abstract: A voltage-glitch detection circuit includes a voltage comparator having two input terminals with different capacitance resistance charge/discharge time. Voltage dividers are coupled to the two input terminals of the voltage comparator respectively, and commonly receive a supply voltage. One of the voltage dividers is supplied to the voltage comparator as a reference voltage of the voltage comparator, and the other is supplied as a glitch detection voltage to the voltage comparator.

Power supply voltage droop compensated clock modulation for microprocessors

Abstract: A voltage source droop compensated clock modulation for microprocessors is described Specifically, the circuit reduces the clock frequency if a voltage source droop is detected

A novel control method for multiphase voltage regulators

Abstract: This paper proposes a novel control method for the multiphase voltage regulators (VRs) to power the next generation of microprocessors. With a simple structure, this control can achieve multiphase current sharing, very fast transient response, and adaptive output voltage regulation. Simulation and experimental results show that the proposed control scheme significantly improves the performance, as compared with existing control methods.

Capacitive load drive circuit and plasma display apparatus

Abstract: A capacitive load circuit and a plasma display apparatus using such a circuit, being able to use a sustain transistor having a voltage rating in accordance with a sustain voltage even when a voltage larger than the sustain voltage is applied to a sustain electrode, have been disclosed, wherein a switch whose one end is connected to a capacitive load is comprised and when a third voltage, whose voltage difference from a second voltage is larger than the voltage difference between a first voltage and the second voltage, is applied to the capacitive load, a fourth voltage is selectively applied to the other end of the switch.

High voltage ripple reduction and substrate protection

Abstract: In a non-volatile memory, charge pumps are used to provide high voltages needed for programming memory cells that have floating gate structures. Charge pumps have a series of voltage multiplier stages in series to boost voltage. These charge pumps must rapidly charge a load to a high voltage and then maintain a voltage with a high degree of stability. Techniques for achieving both of these goals are presented. In one aspect, a charge pump has two operating states, one to charge a load rapidly and a second to maintain a voltage on a charged load with high stability. These states are achieved by changing the current output from a high current during charging to a low current to maintain the voltage. This is done by changing the capacitance used in the individual voltage multiplier stages. In another aspect, two different current levels are produced by changing the voltage used to charge the capacitors of the voltage multiplier stages.

Hybrid regulator with switching and linear sections

Abstract: A power supply system includes a non-linear section that provides an intermediate voltage. A linear section receives the intermediate voltage and generates the output voltage. The linear section forms a control signal that is used by the non-linear section to change the value of the intermediate voltage as the output voltage changes to keep the differential voltage across the linear section low.

A wireless load sharing controller to improve dynamic performance of parallel-connected UPS inverters

Abstract: In this paper, a new control scheme for parallel-connected inverters without communication wires is presented. This wireless control technique is based on the well-known droop method, which consists of introducing P-/spl omega/ and Q-V schemes into the inverters, in order to share properly the power drawn to the loads. In the literature, the droop method has been widely discussed in applications of load sharing between different parallel-connected UPS inverters. However, there are little reports about its transient performance. Some previous works present a small signal stability analysis for parallel-connected inverter system. Nevertheless, by using the conventional droop approach, there is no possibility to modify the transient response without the loss of power sharing precision or output-voltage and frequency accuracy. In this work, a great improvement in transient response is achieved by introducing power derivative-integral terms into a conventional droop scheme. Hence, better controllability of the system is obtained and, consequently, proper transient performance can be achieved. Simulation and experimental results are presented to prove the validity of this approach, which shows excellent performance in front of conventional one.