Showing papers on "Voltage regulator published in 2009"

An efficient piezoelectric energy-harvesting interface circuit using a bias-flip rectifier and shared inductor

Abstract: Energy harvesting is an emerging technology with applications to handheld, portable and implantable electronics. Harvesting ambient vibration energy through piezoelectric (PE) means is a popular energy harvesting technique that can potentially supply 10 to 100's of µW of available power [1]. One of the limitations of existing PE harvesters is in their interface circuitry. Commonly used full-bridge rectifiers and voltage doublers [2] severely limit the electrical power extractable from a PE harvesting element. Further, the power consumed in the control circuits of these harvesters reduces the amount of usable electrical power. In this paper, a bias-flip rectifier that can improve upon the power extraction capability of existing full-bridge rectifiers by up to 4.2× is presented. An efficient control circuit with embedded DC-DC converters that can share their filter inductor with the bias-flip rectifier thereby reducing the volume and component count of the overall solution is demonstrated.

Method and system of regulating voltages

Abstract: Regulating voltages At least some of the illustrative embodiments are systems including a switching circuit configured to produce an intermediate voltage signal from an input voltage signal, and a first voltage regulator coupled the switching circuit and configured to produce a first regulated voltage signal from the intermediate voltage signal The switching circuit is configured to create the intermediate voltage signal based on a switching signal having a duty cycle, and wherein the duty cycle of the switching signal is open-loop with respect the intermediate voltage signal and the first regulated voltage signal

Ripple-Based Control of Switching Regulators—An Overview

Abstract: Switching regulators with ripple-based control (ie, ?ripple regulators?) are conceptually simple, have fast transient responses to both line and load perturbations, and some versions operate with a switching frequency that is proportional to the load current under the discontinuous conduction mode These characteristics make the ripple regulators well-suited, especially for power management applications in computers and portable electronic devices Ripple regulators also have some drawbacks, including (in some versions) a poorly defined switching frequency, noise-induced jitter, inadequate dc regulation, and a tendency for fast-scale instability This paper presents an overview of the various ripple-based control techniques, discusses their merits and limitations, and introduces techniques for reducing the noise sensitivity and the sensitivity to capacitor parameters, improving the frequency stability and the dc regulation, and avoiding fast-scale instability

A Control Methodology and Characterization of Dynamics for a Photovoltaic (PV) System Interfaced With a Distribution Network

Abstract: This paper proposes a control strategy for a single-stage, three-phase, photovoltaic (PV) system that is connected to a distribution network. The control is based on an inner current-control loop and an outer DC-link voltage regulator. The current-control mechanism decouples the PV system dynamics from those of the network and the loads. The DC-link voltage-control scheme enables control and maximization of the real power output. Proper feedforward actions are proposed for the current-control loop to make its dynamics independent of those of the rest of the system. Further, a feedforward compensation mechanism is proposed for the DC-link voltage-control loop, to make the PV system dynamics immune to the PV array nonlinear characteristic. This, in turn, permits the design and optimization of the PV system controllers for a wide range of operating conditions. A modal/sensitivity analysis is also conducted on a linearized model of the overall system, to characterize dynamic properties of the system, to evaluate robustness of the controllers, and to identify the nature of interactions between the PV system and the network/loads. The results of the modal analysis confirm that under the proposed control strategy, dynamics of the PV system are decoupled from those of the distribution network and, therefore, the PV system does not destabilize the distribution network. It is also shown that the PV system dynamics are not influenced by those of the network (i.e., the PV system maintains its stability and dynamic properties despite major variations in the line length, line X/R ratio, load type, and load distance from the PV system).

Analysis, Design, and Control of a Transcutaneous Power Regulator for Artificial Hearts

Abstract: Based on a generic transcutaneous transformer model, a remote power supply using a resonant topology for use in artificial hearts is analyzed and designed for easy controllability and high efficiency. The primary and secondary windings of the transcutaneous transformer are positioned outside and inside the human body, respectively. In such a transformer, the alignment and gap may change with external positioning. As a result, the coupling coefficient of the transcutaneous transformer is also varying, and so are the two large leakage inductances and the mutual inductance. Resonant-tank circuits with varying resonant-frequency are formed from the transformer inductors and external capacitors. For a given range of coupling coefficients, an operating frequency corresponding to a particular coupling coefficient can be found, for which the voltage transfer function is insensitive to load. Prior works have used frequency modulation to regulate the output voltage under varying load and transformer coupling. The use of frequency modulation may require a wide control frequency range which may extend well above the load insensitive frequency. In this paper, study of the input-to-output voltage transfer function is carried out, and a control method is proposed to lock the switching frequency at just above the load insensitive frequency for optimized efficiency at heavy loads. Specifically, operation at above resonant of the resonant circuits is maintained under varying coupling-coefficient. Using a digital-phase-lock-loop (PLL), zero-voltage switching is achieved in a full-bridge converter which is also programmed to provide output voltage regulation via pulsewidth modulation (PWM). A prototype transcutaneous power regulator is built and found to to perform excellently with high efficiency and tight regulation under variations of the alignment or gap of the transcutaneous transformer, load and input voltage.

Nonvolatile semiconductor memory device

Abstract: Provided is a nonvolatile semiconductor memory device which can enhance a stable control of a voltage applied to a memory cell and has excellent capability of controlling a drain voltage The nonvolatile semiconductor memory device includes: a plurality of memory cells; a write buffer receiving data to be written to the plurality of memory cells; a count circuit searching data input to the write buffer and determining bit number of data to be simultaneously programmed to the plurality of memory cells; a write circuit supplying a write voltage to the plurality of memory cells according to the data; and a voltage regulator supplying a control voltage (Vpb) to the write circuit, wherein the voltage regulator includes a controller Counting write bit number and supplying the control voltage (Vpb) according to the counted write bit number

A Versatile Control Scheme for a Dynamic Voltage Restorer for Power-Quality Improvement

Abstract: This paper presents a control system based on a repetitive controller to compensate for key power-quality disturbances, namely voltage sags, harmonic voltages, and voltage imbalances, using a dynamic voltage restorer (DVR). The control scheme deals with all three disturbances simultaneously within a bandwidth. The control structure is quite simple and yet very robust; it contains a feedforward term to improve the transient response and a feedback term to enable zero error in steady state. The well-developed graphical facilities available in PSCAD/EMTDC are used to carry out all modeling aspects of the repetitive controller and test system. Simulation results show that the control approach performs very effectively and yields excellent voltage regulation.

Small-Signal Model-Based Control Strategy for Balancing Individual DC Capacitor Voltages in Cascade Multilevel Inverter-Based STATCOM

Abstract: This paper presents a new feedback control strategy for balancing individual DC capacitor voltages in a three-phase cascade multilevel inverter-based static synchronous compensator. The design of the control strategy is based on the detailed small-signal model. The key part of the proposed controller is a compensator to cancel the variation parts in the model. The controller can balance individual DC capacitor voltages when H-bridges run with different switching patterns and have parameter variations. It has two advantages: 1) the controller can work well in all operation modes (the capacitive mode, the inductive mode, and the standby mode) and 2) the impact of the individual DC voltage controller on the voltage quality is small. Simulation results and experimental results verify the performance of the controller.

Method and apparatus for controlling a hybrid power system

Abstract: The present invention provides a simplified method of controlling power among the various sources and loads in a power system. Power generating sources are each connected to a common DC bus through a converter. The converter selectively transfers energy to the DC bus at a maximum rate or at a reduced rate according to the level of the DC voltage present on the DC bus. At least one storage device is preferably connected to the common DC bus through a power regulator. The power regulator selectively transfers energy to or from the DC bus as a function of DC voltage level present on the DC bus. Further, an inverter may be provided to bidirectionally convert between the DC voltage and an AC voltage for connection to a customer load or the utility grid. Each power conversion device is independently controlled to provide a modular and simplified power control system.

A Practical Switching Loss Model for Buck Voltage Regulators

Abstract: In this paper, a review of switching loss mechanisms for synchronous buck voltage regulators (VRs) is presented. Following the review, a new simple and accurate analytical switching loss model is proposed for synchronous buck VRs. The model includes the impact of common source inductance and switch parasitic inductances on switching loss. The proposed model uses simple equations to calculate the rise and fall times and piecewise linear approximations of the high-side MOSFET voltage and current waveforms to allow quick and accurate calculation of switching loss in a synchronous buck VR. A simulation program with integrated circuit emphasis (Spice) simulations are used to demonstrate the accuracy of the voltage source driver model operating in a 1-MHz synchronous buck VR at 12-V input, 1.3-V output. Switching loss was estimated with the proposed model and compared to Spice measurements. Experimental results are presented to demonstrate the accuracy of the proposed model.

A 45 nm 8-Core Enterprise Xeon¯ Processor

Abstract: This paper describes a 2.3 Billion transistors, 8-core, 16-thread, 64-bit Xeon® EX processor with a 24 MB shared L3 cache implemented in a 45 nm nine-metal process. Multiple clock and voltage domains are used to reduce power consumption. Long channel devices and cache sleep mode are used to minimize leakage. Core and cache recovery improve manufacturing yields and enable multiple product flavors from the same silicon die. The disabled blocks are both clock and power gated to minimize their power consumption. Idle power is reduced by shutting off the unterminated I/O links and shedding phases in the voltage regulator to improve the power conversion efficiency.

Design and analysis of dynamic voltage restorer for deep voltage sag and harmonic compensation

Abstract: A dynamic voltage restorer (DVR) to compensate deep voltage sags and harmonics is proposed. The DVR consists of shunt and series converters connected back-to-back through a dc-to-dc step up converter. The presence of the dc-to-dc step converter permits the DVR to compensate deep voltage sags for long duration. The series converter is connected to the supply side whereas the shunt converter is connected to the load side. With this configuration, there is no need for large dc capacitors. A design procedure for the components of the DVR is presented under a voltage sag condition. The control system of the proposed DVR is based on hysteresis voltage control. Besides voltage sag compensation, the capability of compensating load voltage harmonics has been added to the DVR to increase the power quality benefits to the load with almost negligible effect on the sag compensation capability. The proposed DVR is modelled and simulated using SIMULINK/MATLAB environment. Time domain simulations are used to verify the operation of the DVR with linear and non-linear loads.

Dynamic Voltage Restorer Based on Flying Capacitor Multilevel Converters Operated by Repetitive Control

Abstract: This paper presents the control system based on the so-called repetitive control for a five-level flying-capacitor dynamic voltage restorer (DVR). This DVR multilevel topology is suitable for medium-voltage applications and operated by the control scheme developed in this paper. It is able to mitigate power-quality disturbances, such as voltage sags, harmonic voltages, and voltage imbalances simultaneously within a bandwidth. The control structure has been divided into three subsystems; the first one improves the transient response of the filter used to eliminate the modulation high-frequency harmonics, the second one deals with the load voltage; and the third is charged with maintaining balanced voltages in the flying capacitors. The well-developed graphical facilities available in PSCAD/EMTDC are used to carry out all modelling aspects of the repetitive controller and test system. Simulation results show that the control approach performs very effectively and yields excellent voltage regulation.

Digital Combination of Buck and Boost Converters to Control a Positive Buck–Boost Converter and Improve the Output Transients

Abstract: A highly efficient and novel control strategy for improving the transients in the output voltage of a DC-DC positive buck-boost converter, required for low-power portable electronic applications, is presented in this paper. The proposed control technique can regulate the output voltage for variable input voltage, which is higher, lower, or equal to the output voltage. There are several existing solutions to these problems, and selecting the best approach involves a tradeoff among cost, efficiency, and output noise or ripple. In the proposed method, instead of instantaneous transition from buck to boost mode, intermediate combination modes consisting of several buck modes followed by several boost modes are utilized to distribute the voltage transients. This is unique of its kind from the point of view of improving the efficiency and ripple content in the output voltage. Theoretical considerations are presented. Simulation and experimental results are shown to prove the proposed theory.

System and method for providing voltage regulation in a power distribution network

Abstract: A system, device and method for regulating the voltage at a customer premises that is supplied power via a first medium voltage power line is provided. In one embodiment, the method of using a computer system comprises determining medium voltage (MV) data comprising data of the voltage supplied to the first medium voltage power line at a plurality of times, storing the MV data for each of the plurality of times in a memory, determining current data comprising data of a current supplied to the medium voltage power line at the plurality of times, storing the current data at each of the plurality of times in memory in association with the voltage data of the same time. In addition, the method includes receiving low voltage data comprising data of a voltage measurement of a low voltage power line conductor at the customer premises at a plurality of times, storing at least some of the low voltage data in memory in association with MV data that corresponds to the voltage supplied to the first medium voltage power line during the voltage measurement of the low voltage power line conductor, and determining a supply voltage to be supplied to the first medium voltage power line based on the current data stored in memory, MV data stored in memory, and the low voltage data stored in memory.

Practical considerations for designing IPT system for EV battery charging

Abstract: The paper proposes a hands-free Inductive Power Transfer system for charging the batteries of an Electrical Vehicle. A typical system comprises a power supply, a transfer pad on the ground, a receiving pad on the vehicle together and a power regulator. This paper describes the design of the power regulator which must ensure continuous power flow at high efficiency despite wide separation between the charging pads as a result of variation in the vehicle to ground heights. The paper also discusses the need to meet new and stringent electromagnetic field exposure regulations. Measurements show good efficiency across various separations and emissions compliance providing the pad is placed underneath the vehicle.

Output capacitor current as feedback to control a hysteretic voltage regulator

Abstract: A hysteretic voltage regulator is disclosed comprising an inductor having a first end and a second end, wherein the second end is connected to an output capacitor in shunt with a load. A switch connects the first end of the inductor to a supply voltage when an output voltage across the load falls below a reference voltage, and disconnects the first end of the inductor from the supply voltage when a current flowing through the output capacitor rises above a reference current.

Apparatus comprising a brown-out protection circuit for memory devices

Abstract: An apparatus and method for regulating an output voltage (V O ) of a voltage regulator during a brown-out condition is described. The apparatus comprises the voltage regulator, a brown-out protection circuit, a switch, and a first capacitor. The voltage regulator charges the first capacitor to the regulated output voltage V O . The brown-out protection circuit is coupled to the voltage regulator and the switch. In operation, the brown-out protection circuit detects the occurrence of an undervoltage condition based on a first undervoltage detection signal received at an undervoltage detection input, the brown-out protection circuit disables the voltage regulator and closes the switch to discharge the first capacitor to below a predetermined voltage level.

Electronic circuit for driving a diode load

Abstract: An electronic circuit includes circuit portions for identifying a largest voltage drop through one of a plurality of series connected diode strings and for controlling a boost switching regulator according to the largest voltage drop. The electronic circuit can sense an open circuit series connected diode string, which would otherwise have the largest voltage drop, and can disconnect that open circuit series connected diode string from control of the boost switching regulator. Another electronic circuit includes a current limiting circuit coupled to or within a boost switching regulator and configured to operate with a diode load. Another electronic circuit includes a pulse width modulation circuit configured to dim a series connected string of light emitting diodes.

AC LED dimmer and dimming method thereby

Abstract: The disclosure relates to an AC LED dimmer and dimming method thereof. The AC LED dimmer includes a rectifier receiving AC voltage from an AC voltage source and full-wave rectifying the AC voltage; a direct current (DC)/DC converter receiving the full-wave rectified voltage from the rectifier, generating a full-wave rectified stepped-up voltage, and generating a pulse enable signal; a pulse width modulation controller receiving the full-wave rectified stepped-up voltage and generating a pulse width modulation signal to dim an AC LED in response to the pulse enable signal; a switch driving the AC LED under control of the pulse width modulation signal, and an electromagnetic interference (EMI) filter to be connected between the AC voltage source and the switch to eliminate electromagnetic interference from the AC voltage source. Accordingly, the dimmer can perform an efficient and linear dimming function and suppress harmonics.

Methods and circuits for LED drivers and for PWM dimming controls

Abstract: The present invention relates to methods for LED driver applications, comprising the steps: providing an input voltage, V in ; generating an output voltage, V out , for driving a plurality of LED channels, wherein a boost converter is used to convert the input voltage V in to the output voltage V out ; determining a lowest voltage, V LVS , from the LED channels; generating a comparator voltage, V comp , by comparing the lowest voltage of the channels, V LVS, with a feedback reference voltage, V FBREF , wherein the feedback reference voltage, V FBREF , and a LED current, I LED , for the LED channels are determined by a current I SET ; generating a summed voltage, V sum , for stabilizing the output voltage, V out ; and generating a PWM voltage, V PWM , as a function of the V comp and the V sum to control the output voltage, V out .

Dynamic voltage restorer based on a four-leg voltage source converter

Abstract: Analysis and control of a dynamic voltage restorer are described. The voltage restorer is based on a four-leg voltage source converter. The three-phase input variables are resolved into the positive, negative and zero-sequence components using a weighted, recursive, least-squares estimator. Identical controllers have been used for each sequence component. A laboratory model of the restorer has been constructed and its performance has been tested by simulation and experiments.

Optimal VAR Control Considering Wind Farms Using Probabilistic Load-Flow and Gray-Based Genetic Algorithms

Abstract: Techniques for distributed generations (DGs) have attracted increasing attention due to considerations of environmental sustainability. Wind farms are one of the DGs, and they have intermittent characteristics. This paper presents a method using wind generator voltages, static compensators, and transformer taps as controllers to regulate the voltage profile for operation planning in a distribution system. Wind power generations and bus loads are modeled with random variables. Through gray-based genetic algorithms (GAs), the MW loss in the system is minimized and the operational constraints are fulfilled. Moreover, this paper uses the cumulant method to calculate the bus voltage fluctuation by using the algebraic addition and multiplication to avoid convolution. The probability density function of the voltage fluctuation can be further expressed by the Gram-Charlier series expansion. Applicability of the proposed method is verified through simulation by using a 17-bus system and an autonomous 24-bus (Penghu) system.

A Sinusoidal PWM Method With Voltage Balancing Capability for Diode-Clamped Five-Level Converters

Abstract: This paper presents a novel sinusoidal pulsewidth modulation control method with voltage balancing capability for the diode-clamped five-level rectifier/inverter system. A complete analysis of the voltage balance theory is given. The voltage balancing effects of the third harmonic offset injection to all three-phase voltages are discussed. The proposed control utilizes the offset voltage to regulate the average currents flowing into and out of the inner junction without affecting output line-to-line voltage. The voltage balancing was achieved by selecting proper offset voltages for both sides. A five-level experimental system is built up and used to prove the theory.

Voltage limitation by autonomous reactive power control of grid connected photovoltaic inverters

Abstract: The increasing decentralized power generation in the public low voltage grid may lead to a reversed load flow. The common assumption that the highest voltage in a low voltage grid is on the transformer busbar is then no longer appropriate. Therefore the risk of overvoltages rises significantly. A highly effective way to keep the voltage within the allowed bandwidth is to utilize the ability of modern voltage source converters (VSC) to provide or absorb reactive power while feeding active power into the network (4-quadrant operation). With a reactive power consumption while active power is fed in the voltage rise can be limited. For practical use a grid adaptive reactive power control system which works without manual set up or communication requirements is desirable. Therefore an exemplary adaptive control system was designed, modeled in a load flow simulation program and tested on different low voltage (LV) grid models for network classes prone to voltage problems. The results show that simple parameter sets can be found which will work on most grid infrastructures without further adjustment. But they also show the problems to keep the voltage within the limits without decreasing the maximum grid transport capacity by consuming innecessary reactive power.

Low-Power Supply-Regulation Techniques for Ring Oscillators in Phase-Locked Loops Using a Split-Tuned Architecture

Abstract: A supply-regulated phase-locked loop (PLL) employs a split-tuned architecture to decouple the tradeoff between supply-noise rejection performance and power consumption. By placing the regulator in the low-bandwidth coarse loop, the proposed PLL architecture allows us to maximize its bandwidth to suppress the oscillator phase noise with neither the power supply-noise rejection nor the power dissipation of the regulator being affected. A replica-based regulator introduces a low-frequency pole in its supply-noise transfer function and avoids degradation of supply-noise rejection beyond the regulator-loop's dominant pole frequency. The prototype PLL fabricated in a 0.18 mum digital CMOS process operates from 0.5 to 2.5 GHz. At 1.5 GHz, the proposed PLL achieves 1.9 ps long-term rms jitter and a worst case supply-noise sensitivity of -28 dB (0.5 rad/V), an improvement of 20 dB over conventional solutions, while consuming 2.2 mA from a 1.8 V supply.

Light-Load Efficiency Improvement for Buck Voltage Regulators

Abstract: Extending battery life is a big challenge for today's laptop, and light-load efficiency is very important for battery life extension. In this paper, adaptive ON-time control is proposed to achieve higher efficiency when the buck converter is running in continuous current mode. A novel nonlinear inductor is then proposed to improve discontinuous-current-mode efficiency. A control method with a thorough analysis is proposed for the nonlinear inductor to achieve high efficiency, the required output voltage ripple, and sufficient transient response. The experimental results demonstrate the benefits of the proposed methods.

Dynamic headroom control for lcd driver

Abstract: An LED driver controller comprises a voltage regulator for controlling an output voltage to a top of a plurality of LED strings responsive to at least a reference voltage. A plurality of first circuitries each associated with a node at a bottom of each of the plurality of LED strings compares a voltage at the bottom of each of the plurality of LED strings with a high reference voltage and a low reference voltage. Control logic generates a first control signal when the voltage at the bottom of each node of the plurality of LED strings exceeds the high reference voltage and generates a second control signal when the voltage at least one of node of the plurality of LED strings falls below the low reference voltage. Second circuitry responsive to the first control signal and the second control signal generates the reference voltage. The reference voltage is controlled to cause the voltage at the bottom of the lowest voltage node of the plurality of LED strings to remain between the high reference voltage and the low reference voltage.

Switch-Mode Voltage Regulator

Abstract: The invention concerns a switch-mode voltage regulator, comprising : an inductor (L); a generator for producing a voltage ramp ( 16 ); circuitry ( 12, 13 ) for producing at least one pulse stream from said voltage ramp; switch control circuitry ( 14 ) for controlling switching of a current in the inductor according to said pulse stream; and a first control loop adapted to modulate the form of the voltage ramp according to the current flowing in the inductor.

A 45nm 8-core enterprise Xeon ® processor

Abstract: A 2.3B transistors, 8-core, 16-thread 64-bit Xeon® EX processor with a 24MB shared L3 cache was implemented in a 45nm 9-metal process. Multiple clock and voltage domains are employed to reduce power consumption. Long channel devices and cache sleep mode are used to minimize leakage. Core and cache recovery improve manufacturing yields and enable multiple product flavors using the same silicon die and package. The disabled blocks are both clock and power gated to minimize their power consumption. Idle power is reduced by shutting off the un-terminated I/O links and shedding phases in the voltage regulator to improve the power conversion efficiency.