Showing papers on "Voltage regulator published in 1999"

Power distribution system design methodology and capacitor selection for modern CMOS technology

Abstract: Power systems for modern complementary metal-oxide-semiconductor (CMOS) technology are becoming harder to design. One design methodology is to identify a target impedance to be met across a broad frequency range and specify components to meet that impedance. The impedance versus frequency profiles of the power distribution system components including the voltage regulator module, bulk decoupling capacitors and high frequency ceramic capacitors are defined and reduced to simulation program with integrated circuit emphasis (SPICE) models. A sufficient number of capacitors are placed in parallel to meet the target impedance. Ceramic capacitor equivalent series resistance (ESR) and ESL are extremely important parameters in determining how many capacitors are required. SPICE models are then analyzed in the time domain to find the response to load transients.

Phillips-Heffron model of power systems installed with STATCOM and applications

Abstract: The paper establishes the linearised Phillips-Heffron model of a power system installed with a static synchronous compensator (STATCOM) and demonstrates the application of the model in analysing the damping effect of the STATCOM and designing a STATCOM stabiliser to improve power system oscillation stability. Both cases of single-machine infinite-bus and multimachine power systems are studied and example power systems are presented. These show the negative damping influence of a STATCOM DC voltage regulator on power system oscillations and the effectiveness of the STATCOM stabiliser superimposed on a STATCOM AC voltage regulator to counterattack the negative damping effect.

Digital PWM control: application in voltage regulation modules

Abstract: Conventionally, controllers for DC/DC converters have relied on analog circuit techniques for implementation. While analog based systems have proven successful, several reasons make digital control attractive. Digital control allows for the implementation of more functional control schemes. Digital circuits are potentially less susceptible to noise and parameter variations. With the explosion of cheap computing power, and availability of advanced integrated circuit design and synthesis tools, a digital controller design can be ported to new integrated circuit technology generations with little additional effort. Current trends in microprocessor designs lead toward decreasing supply voltages and increasing current demands. Future microprocessors are projected to require between 30-60 Amps of static current and impose di/dt requirements on the power supply in the order of 5 A/ns. In this paper, we focus on the design of a digital controller for an interleaved DC/DC buck converter to supply power for microprocessor loads. Digital logic makes the generation of identical, but delayed, gate drive signals for the various phases of the interleaved converter simple.

A fully digital, energy-efficient, adaptive power-supply regulator

Abstract: A voltage scaling technique for energy-efficient operation requires an adaptive power-supply regulator to significantly reduce dynamic power consumption in synchronous digital circuits. A digitally controlled power converter that dynamically tracks circuit performance with a ring oscillator and regulates the supply voltage to the minimum required to operate at a desired frequency is presented. This paper investigates the issues involved in designing a fully digital power converter and describes a design fabricated in a MOSIS 0.8-/spl mu/m process. A variable-frequency digital controller design takes advantage of the power savings available through adaptive supply-voltage scaling and demonstrates converter efficiency greater than 90% over a dynamic range of regulated voltage levels.

Application of a multivariable feedback linearization scheme for rotor angle stability and voltage regulation of power systems

Abstract: This paper investigates the application of a nonlinear controller to the multi-input multi-output model of a system consisting of a hydraulic turbine and a synchronous generator. The controller proposed is based on a feedback linearization scheme. Its main goal is to control the rotor angle as well as the terminal voltage, to improve the system's stability and damping properties under large disturbances and to obtain good post-fault voltage regulation. The response of the system is simulated in the presence of a short-circuit at the terminal of the machine in two different configurations and compared to the performance of a standard IEEE type 1 voltage regulator, PSS and a PID speed regulator.

Adaptive repetitive control of PWM inverters for very low THD AC-voltage regulation with unknown loads

Abstract: An adaptive repetitive control scheme is proposed and applied to the control of a pulsewidth-modulated (PWM) inverter used in a high-performance AC power supply. The proposed control scheme can adaptively eliminate periodic distortions caused by unknown periodic load disturbances in an AC power supply. The proposed adaptive repetitive controller consists of a voltage regulator using state feedback control, a repetitive controller with tuning parameters and an adaptive controller with a recursive least-squares estimator (LSE). This adaptive repetitive controller designed for AC voltage regulation has been realized using a single-chip digital signal processor (DSP) TMS320C14 from Texas Instruments. Experimental verification has been carried out on a 2 kVA PWM inverter. Simulation and experimental results show that the DSP-based adaptive repetitive controller can achieve both good dynamic response and low total harmonic distortion (THD) under large-load disturbances and uncertainties.

Volt/VAr control at distribution substations

Abstract: This paper proposes new methods to improve the performance of the current volt/VAr control schemes at distribution substations. The approach makes use of the new measurement and computer resources that are now available at the substations. The paper shows that new supervisory type control schemes can be developed to improve the performance of both the voltage regulator controllers and also the substation capacitor controllers that are used at the substations for volt/VAr control. The new voltage regulator controller makes use of the voltage drop characteristics of the feeders it regulates. The capacitor controller uses local real and reactive power measurements for power factor control at the substation.

Control of energy optimized dynamic voltage restorer

Abstract: The dynamic voltage restorer (DVR) is a custom power device used for voltage compensation of sensitive loads against voltage disturbances in power distribution lines. This paper illustrates a correction technique, which draws a minimum amount of energy from the DVR during the process of compensation of a voltage sag or swell. Using the proposed method it can be shown that a particular disturbance can be corrected with less amount of storage energy compared to that of existing in-phase boosting method. The paper also discusses a multiloop feedback control method applicable for the DVR to obtain good dynamic performance.

Voltage regulation employing a composite feedback signal

Abstract: A switching power supply produces a regulated output voltage. An output inductor is connected at one end to a power switch circuit having a duty cycle. The other end of the output inductor has a regulated output voltage. A voltage feedback circuit produces a voltage feedback signal representative of the regulated output voltage. A current feedback circuit produces a composite signal representative of inductor current, the composite signal having an ac component and a dc component. An error amplifier produces an error signal representative of the difference between a reference voltage and the voltage feedback signal. A pulse width modulator comparator compares the error signal to a composite signal representing a summing of the voltage feedback signal with a current sensing signal representative of output inductor current, the composite signal having an ac component and a dc component. The comparator output results in a gate drive signal that controls the duty cycle of the power switch circuit to maintain the regulated output voltage.

Charge pump circuit adjustable in response to an external voltage source

Abstract: An integrated circuit detects the voltage level of the supply voltage to the integrated circuit. Circuity on the integrated circuit including the charge pump circuity adjusts to operate more effectively or efficiently at the voltage level of the supply voltage.

Circuit and method for reducing quiescent current in a switching regulator

Abstract: A switching mode voltage regulator circuit that operates at reduced quiescent current levels is provided. The voltage regulator preferably includes a control circuit and a switching element that connects and disconnects filter circuitry from the control circuit. An error amplifier in the control circuit is placed in a micropower operating state when the regulator is in standby mode to reduce quiescent current.

A high power density, high efficiency and fast transient voltage regulator module with a novel current sensing and current sharing technique

Abstract: Future generations of microprocessors are expected to exhibit much heavier loads and much faster transient slew rates. Today's voltage regulator module (VRM) will need a large amount of extra decoupling and output filter capacitors to meet future requirements, which basically makes the existing VRM topologies impractical. As a candidate topology, the interleaved quasi-square-wave (QSW) exhibits very good performance, such as fast transient response and very high power density. The limitation in the application of the interleaved parallel technology is current sharing control. In this paper, a novel current sensing and current sharing technique is proposed. With this technique, current sharing can be controlled simply in parallel converters without current transformer and current sensing resistors. Experimental results verify that with this technique, a 4-module interleaved QSW VRM has high power density, high efficiency and fast transient response.

High-efficiency modulation RF amplifier

Abstract: The present invention, generally speaking, provides for high-efficiency power control of a high-efficiency (e.g., hard-limiting or switch-mode) power amplifier in such a manner as to achieve a desired modulation. In one embodiment, the spread between a maximum frequency of the desired modulation and the operating frequency of a switch-mode DC-DC converter is reduced by following the switch-mode converter with an active linear regulator. The linear regulator is designed so as to control the operating voltage of the power amplifier with sufficient bandwidth to faithfully reproduce the desired amplitude modulation waveform. The linear regulator is further designed to reject variations on its input voltage even while the output voltage is changed in response to an applied control signal. This rejection will occur even though the variations on the input voltage are of commensurate or even lower frequency than that of the controlled output variation. Amplitude modulation may be achieved by directly or effectively varying the operating voltage on the power amplifier while simultaneously achieving high efficiency in the conversion of primary DC power to the amplitude modulated output signal. High efficiency is enhanced by allowing the switch-mode DC-to-DC converter to also vary its output voltage such that the voltage drop across the linear regulator is kept at a low and relatively constant level. Time-division multiple access (TDMA) bursting capability may be combined with efficient amplitude modulation, with control of these functions being combined. In addition, the variation of average output power level in accordance with commands from a communications system may also be combined within the same structure.

Arrangement for decentralized supply of regenerative energy performs voltage regulation at combination point for controlled improvement of quality of electrical supply

Abstract: The arrangement regulates the voltage at a combination point for controlled electrical supply quality improvement. The arrangement for supplying power and the voltage regulator are in one unit. The regulator has arrangements for specifying a desired voltage spectrum at the combination point, diagnosing the state of the supply network and determining demand values of harmonics and/or a fundamental frequency reactive power to be compensated. The arrangement performs voltage regulation at a combination point for controlled improvement of the quality of the electrical supply. The arrangement for supplying power and the voltage regulator are contained in one unit. The regulator (17,20) has arrangements for specifying a desired voltage spectrum at the combination point, for diagnosing the state of the supply network and for determining demand values of harmonics to be compensated and/or a fundamental frequency reactive power to be compensated. Independent claims are also included for the following: a current converter.

Design of a robust voltage controller for a buck-boost converter using /spl mu/-synthesis

Abstract: Proposes the structured singular value (/spl mu/) approach to the problem of designing an output voltage regulator for a buck-boost converter with current-mode control. This approach allows a quantitative description of the effects of reactive components' tolerances and operating point variations, which strongly affect the converter dynamics. First, a suitable linear converter model is derived, whose parameter variations are described in terms of perturbations of the linear fractional transformation (LFT) class. Then, /spl mu/-analysis is used to evaluate the robustness of a conventional PI voltage regulator with respect to the modeled perturbations. Finally, the approximate /spl mu/-synthesis procedure known as D-K iteration is used to design a robustly performing regulator. Simulation results are presented, describing the small and large signal behavior of a reduced order approximation of the /spl mu/-synthesized controller.

Method and apparatus for digital voltage regulation

Abstract: A digital voltage regulator has an input terminal (20) coupled to an input voltage source (12), an output terminal (22) coupled to a load (14), and a plurality of switching circuits (24) to alternately couple and decouple the input terminal (20) to the output terminal (22). An estimated current is calculated for each switching circuit (24), each estimated current representing a current passing through an inductor (34) associated with the switching circuit (24). A total desired output current to pass throught the inductor (34) is calculated which will maintain an output voltage at the output terminal (22) substantially constant. The switching circuits (24) are controlled based on the estimated current and the total desired output current so that a total current passing through the inductor (34) is approximately equal to the total desired output current.

Single shot transient suppressor (SSTS) for high current high slew rate microprocessor

Abstract: Future generation microprocessors are predicted to exhibit heavier loads and faster transients. Conventional voltage regulator modules (VRM) need a large amount of output filter capacitors to meet future requirements and a huge number of decoupling capacitors, mainly due to the presence of parasitic inductance between the VRM and the microprocessor. In this paper, a new active damp concept is presented. By charging some auxiliary capacitors at higher voltage, it is possible to store the amount of charge required by the processor during the step up transient; this extra charge can be locally delivered to the processor in a single shot manner, bypassing the slower VRM. In the same way, this circuit can sink the excess of charge that has to be removed during the step down transient. By using this transient suppressor circuit, a conventional VRM can still provide adequate steady state regulation, while the size of decoupling and filter capacitors can be significantly reduced. Experimental results prove the validity of the concept.

Real-time task scheduling for a variable voltage processor

Abstract: This paper presents a real-time task scheduling technique with a variable voltage processor which can vary its supply voltage dynamically. Using such a processor, running tasks with a low supply voltage leads to drastic power reduction. However, reducing the supply voltage may violate real-time constraints. In this paper, we propose a scheduling technique which simultaneously assigns both CPU time and a supply voltage to each task so as to minimize total energy consumption while satisfying all real-time constraints. Experimental results demonstrate effectiveness of the proposed technique.

Method and apparatus for feedback control of switch mode power supply output to linear regulators

Abstract: A method and apparatus for using feedback to control the output voltage of a Switch Mode Power Supply (SMPS) that is used as the input voltage to subsequent Low Drop Out (LDO) linear voltage regulators. A multiplexer and Analog to Digital Converter (ADC) are used to successively sample the output voltages of multiple parallel LDO regulators. The digitized voltage values are input to a digital processor that compares the LDO regulator output voltages with acceptable limits previously stored in memory. The digitized voltage values are used by the digital processor to control the output voltage of a SMPS that is used as the input voltage to the LDO regulators. The output voltage of the SMPS, and thus the input of the LDO regulators, is reduced to the minimum value that retains full performance of the LDO regulators. Operating each LDO regulator at full regulation ensures full performance of the LDO regulators. Minimizing the input voltage to the LDO regulators maximizes the efficiency of the total power supply. When integrated into a battery powered cellular phone, the invention maximizes efficiency thereby maximizing telephone talk time and standby time.

Common mode voltage reduction method modifying the distribution of zero voltage vector in PWM converter/inverter system

Abstract: This paper proposes a new space-vector pulsewidth modulation (PWM) strategy that can restrict the common-mode voltage within one-third of DC-bus voltage in a PWM converter/inverter system with the synchronization of the switching sequence. In this paper, the generation of the common-mode voltage pulse whose magnitude reaches two-thirds of DC-bus voltage is investigated and the elimination method of this voltage pulse is presented. The proposed method can be easily implemented in software and requires no extra hardware without degradation in control performance of PWM converter/inverter-fed AC motor drives.

Dual voltage electrical distribution system

Abstract: The invention is designed for vehicles having two electrical power supply systems and corresponding differentiated voltage level charges and two batteries operating at a first and a second voltage level. A bidirectional voltage converter cooperates with both systems whose input and output stages are galvanically insulated and include a switch. The batteries are connected to said input and output at a first and a second voltage level so that said bidirectional converter can provide a first reduced voltage mode and a second increased voltage mode . The passive components, e.g. the magnetic components and capacitances, of said stages have been chosen to provide an identical transitional behavior in both modes when a disruption occurs in the regulating system either in the charge or the input voltage.

Overcharge protection device and methods for lithium-based rechargeable batteries

Abstract: A protection circuit (100) and protection device (300) for protecting a rechargeable (lithium-based) battery cell or cells from overcharging A voltage regulator element (110, 310) is connected in parrallel with the battery cell or cells (5) and is thermally coupled to a thermal element (120, 322, 326) connected in series with the charging current supply The voltage regulator element (110, 310) prevents overcharging of the battery (5) by shunting current away from the battery when a predetermined voltage across the battery is exceeded Moreover, the thermal element (120, 322, 326) prevents failure of the voltage regulator element (110, 310) by open circuiting the current path when the heat dissipated by the voltage regulator element (110, 310), thermally coupled to the thermal element (120, 322, 326) causes the thermal element to enter a high resistance state Additional protection may be provided by fuse bonds (332, 334) connecting the combination of the shunt voltage regulator (310) and the thermal elements (322, 326) to the charging current supply and to the battery (5)

The adverse effects of excitation system VAr and power factor controllers

Abstract: The trend toward automation of today's power stations has prompted an increased demand for excitation systems having voltage regulators with the ability to automatically regulate generator reactive power (VAr) output or power factor (PF). While not really a new type of control, automatic VAr and PF controllers are appearing in the specifications of more and more power plants and generator voltage regulators. This paper provides a functional description of voltage, VAr, and PF controllers and regulators, along with an example demonstrating the superior steady-state voltage support performance on a transmission system by regulating voltage, rather than VArs or PF. The paper concludes that VAr/PF controllers or regulators should generally not be specified or utilized on excitation controls for voltage supporting generator applications.

A particle swarm optimization for reactive power and voltage control in electric power systems considering voltage security assessment

Abstract: This paper presents a particle swarm optimization (PSO) for reactive power and voltage control (Volt/Var Control: VVC) considering voltage security assessment (VSA). VVC can be formulated as a mixed-integer nonlinear optimization problem (MINLP). The proposed method expands the original PSO to handle a MINLP and determines an on-line VVC strategy with continuous and discrete control variables such as automatic voltage regulator (AVR) operating values of generators, tap positions of on-load tap changer (OLTC) of transformers, and the number of pieces of reactive power compensation equipment. The feasibility of the proposed method is demonstrated and compared with reactive tabu search (RTS) and the enumeration method on practical power system models with promising results.

Compensation circuit for an automotive ignition sensing system

Abstract: In a vehicle having an engine and an ignition system, a sensing circuit is provided for sensing the ignition voltage and providing this sensed signal to various operating modules of the vehicle. The sensing circuit includes a diode/resistor filter that provides a filtered voltage signal at a first output node. A compensation circuit is provided that compensates voltage errors introduced by the filter circuit. The compensation circuit includes a second diode that has substantially identical electrical performance characteristics as the first diode, and that is preferably mounted on a common substrate. A voltage signal at a second output node between the second diode and the filter circuit is indicative of the voltage drop across the second diode, which is further representative of the voltage error introduced by the filter circuit. In one embodiment, the operating module receiving the ignition voltage signal is configured to receive voltage signals at the first and second output nodes. The operating module can include a microprocessor that receives the A/D converted voltage signals and subtracts the signal at the second output node from the signal produced by the filter circuit according to a predetermined relationship. The result of this subtraction is then utilized by other software functions of the operating module that depend upon the ignition voltage signal.

Short circuit protection of IGBTs and other power switching devices

Abstract: A short circuit protection circuit for IGBTs and similar power switch devices Device collector voltage, eg, desaturation voltage, is monitored to detect rapidly the occurrence of a short circuit fault The voltage between the power device emitter and the Kelvin emitter terminals of the device preferably is also monitored and integrated to obtain an estimate of the current flowing through the power switch device Circuit protection is implemented if either the measured collector to emitter voltage exceeds a selected level or the estimated current through the device exceeds a selected level Upon the detection of the fault, a capacitor in parallel with a zener diode is connected between the power switch gate and ground Thus, following a fault, the gate voltage is driven quickly to a low level as the voltage on the gate is discharged through the capacitor The zener diode establishes a clamp voltage at a selected level of gate voltage that permits controlled current flow through the power switching device that is within the capacity of the device so that the device is not damaged A pre-charged capacitor is then connected between the gate and ground to turn off the power switching device gradually as the pre-charged capacitor discharges into the gate The voltage level on the pre-charged capacitor is established by a zener diode connected in parallel thereto

A precise on-chip voltage generator for a gigascale DRAM with a negative word-line scheme

Abstract: A precise on-chip voltage generator for gigascale DRAM's with a negative word-line scheme is described. It combines a charge-pump regulator and a series-pass regulator, and it also includes a positive and negative offset voltage generator that uses a bandgap generator with a differential amplifier. The proposed circuit was experimentally evaluated with a test device fabricated using a 0.3-/spl mu/m process. The simulation results show that the series-pass regulator suppresses the noise on a word-line low voltage (negative) to below 30 mV for the word-line transient and V/sub BB/ bouncing. A dc-voltage error of less than 6% without trimming is confirmed for the positive and negative offset voltage generator through the test device. These results show that the described scheme can be used in future low-voltage gigascale DRAM's.

Voltage balancer device for combination battery

Abstract: A large number of rechargeable unit cells connected in series forming a combination battery are divided into groups of cells, each group including several cells, preferably, three to five cells. Voltage unevenness among the cells in each group is eliminated by operation of a voltage balancer device connected to each group of cells. The voltage balancer device includes a circuit for equally dividing a terminal voltage of the group of cells and obtaining an average voltage among the cells. The average voltage is compared with an individual cell voltage, and the cells having a voltage higher than the average voltage are discharged so that all cell voltages in the group become equal. A plurality of the battery modules each including the group of cells and the voltage balancer device are connected in series to form a single combination battery, and voltage unevenness among the battery modules are controlled by another voltage control device. The voltage unevenness among cells in a group may be eliminated by charging a capacitor from cells having a higher voltage and charging cells having a lower voltage from the charged capacitor. Thus, the voltage unevenness among the combination battery cells is eliminated by a simple and inexpensive device.

Analysis and design of an isolated single-stage converter achieving power-factor correction and fast regulation

Abstract: This paper presents the analysis and design of an isolated single-stage converter achieving high-power-factor correction and fast regulation. By using the technique suggested by Wu et al., a buck-boost converter and a flyback converter can be integrated to form the discussed converter. The buck-boost semistage working in the discontinuous conduction mode (DCM) functions as a power-factor corrector, and the flyback semistage operating in the DCM is a voltage regulator which is controlled, theoretically, to be independent of load variation. An approximated small-signal model of the converter operating in the DCM is developed. Design of a peak-current feedback loop with an optimal proportional integral controller is also presented. A prototype is implemented to verify that the analysis and design are effective and feasible.

Power supply circuit and a voltage level adjusting circuit and method for a portable battery-powered electronic device

Abstract: A power supply circuit for AC/DC adapter-powered or battery-powered portable electronic devices, which has a linear regulator, and includes a voltage level adjusting circuit coupled to the linear regulator. The voltage level adjusting circuit lowers a voltage supplied from the AC/DC adapter to a predetermined level. In an embodiment, the level-adjusted voltage equals a voltage supplied from the battery. The linear regulator is therefore always provided with a constant voltage regardless of the power sources.