Showing papers on "Voltage regulator published in 1993"

Stabilizing a multimachine power system via decentralized feedback linearizing excitation control

Abstract: A new controller for the generator excitation system is described that uses a combination of feedback linearizing and the observation decoupled state space. This creates a controller that can be realistically implemented using only local measurements, and whose performance is consistent with respect to changes in network configuration, loading and power transfer conditions. The control differs in this respect from linear constant-gain controllers such as power system stabilizers, whose characteristics can vary significantly with changes in operating conditions. The design is well-suited to a multimachine setting, in that it is not based on an infinite-bus approximation. Simulations were performed on a 38-bus reduced modelof the Northeast Power Coordinating Council system and benchmarked against simulations in which automatic voltage regulators with power system stabilizers were substituted in place of the nonlinear controls. >

A space vector-based rectifier regulator for AC/DC/AC converters

Abstract: A voltage-sourced rectifier control scheme for use with AC/DC/AC variable speed drives is presented. A control scheme is derived that directly calculates the duration of time spent on the zero state and on each switching state adjacent to the reference vector, over a constant switching interval, in order to drive the line current vector to the reference vector. In addition, under transient conditions, when deadbeat control is not possible, a control scheme is presented that ensures that the line current vector is driven in the direction of the reference current vector. The current reference for the rectifier controller is derived from the bus voltage error and a feedforward term based on the estimated converter output power. The proposed space vector-based rectifier regulator is shown to exhibit improved harmonic and transient performance over existing per-phase duty cycle prediction methods, especially at modulation indices near unity. The deadbeat control of the rectifier input current is accomplished every half-cycle with constant switching frequency while still symmetrically distributing the zero state within the half-cycle period. >

Transient stability enhancement and voltage regulation of power systems

Abstract: Improvement of the transient stability and voltage regulation of a single-machine-infinite-bus power system under the effects of a symmetrical three-phase short-circuit fault is detailed. The dynamical model of the system is described. A design strategy for nonlinear controllers is considered, and the design of a nonlinear variable-structure excitation controller is described. Simulation results obtained using the nonlinear excitation controller are given, and a new nonlinear coordinated controller is proposed. Simulation results obtained by using the nonlinear coordinated controller are presented. >

Technique for decoupling the energy storage system voltage from the DC link voltage in AC electric drive systems

Abstract: An ac electric drive system includes a bidirectional power semiconductor interface between a battery, or an auxiliary energy storage device, and a power inverter for boosting an input do voltage and for decoupling the dc link voltage from the input dc voltage such that the dc link voltage is substantially independent of the input dc voltage and the parameters of the battery or energy storage device. The input dc voltage is controlled to maximize efficiency along predetermined torque envelopes.

Voltage converting circuit and multiphase clock generating circuit used for driving the same

Abstract: A voltage converting circuit of the charge pump step-up type includes a first circuit means for charging each of first and second capacitors with the voltage of a voltage source at a first timing. A second circuit operates to serially connect the charged first capacitor between a positive electrode of the voltage source and a positive voltage output terminal at a second timing so that a positive voltage which is a double of the voltage source voltage, is supplied from positive voltage output terminal. A third circuit operates to the charged first and second capacitors in series between a ground terminal and a negative voltage output terminal at a third timing so that a negative voltage which is a double of the voltage source voltage, is supplied from the negative voltage output terminal. Since the positive voltage and the negative voltage are generated independently of each other, a voltage variation on one of the positive and negative voltage output terminals caused by an external load causes no voltage variation on the other of the positive and negative voltage output terminals.

Three-terminal switched mode power supply integrated circuit

Abstract: An embodiment of the present invention is a three-terminal switched mode power supply chip with a signal terminal for accepting a combination of a feedback control signal and bias supply voltage to operate the chip. A feedback extraction circuit separates the feedback signal from the power supply voltage within the chip by sensing the excess current flowing through a shunt regulator.

Probabilistic load flow in distribution systems containing dispersed wind power generation

Abstract: A probabilistic model for the active power produced and the reactive power absorbed by wind turbines (WTs) equipped with induction generators is developed which takes into account the probabilistic nature of short-term wind velocity forecasts. The model is incorporated in a radial distribution load flow program which allows probabilistic modeling of loads at the MV/LV substation level and of voltage regulator effects at the beginning of the MV distribution feeder. Using this program probabilistic short- and medium-term predictions of the power flows at the various sections of the feeder and of voltage profiles at all nodes of the network are obtained. >

High-frequency link DC/AC converter with suppressed voltage clamp circuits-naturally commutated phase angle control with self turn-off devices

Abstract: High-frequency (HF) link circuit topology is advantageous in realizing compact and light-weight power converters for UPS systems, new energy systems, etc. Among its several circuit configurations, the so called "cycloconverter type" DC/AC converter has its inherent merit of bidirectional power flow and fewer power conversion stages. But, without an additional voltage clamp circuit, a voltage surge occurs at the moment of PWM switching of the cycloconverter due to the stored energy in the leakage inductance at the HF transformer. In this paper, a new approach which adopts only natural-commutation phase angle control for the cycloconverter stage instead of PWM is proposed to remove such voltage clamp circuits. Experimental results of the prototype system which include the application as an AC active filter are also shown.

Nonvolatile memory card with automatic power supply configuration

Abstract: A nonvolatile memory card includes a power supply input for receiving a device power supply voltage for the memory card and a plurality of memories arranged in an array. Each of the plurality of memories receives the device power supply voltage from the power supply input. Each of the plurality of memories receives a device power supply voltage indication signal that indicates voltage level of the device power supply voltage and configures circuitry within each of the plurality of memories to operate in accordance with the voltage level of the device power supply voltage. A voltage detection circuit is coupled to the power supply input for detecting the voltage level of the device power supply voltage and for generating the device power supply voltage indication signal. A logic is coupled to the voltage detection circuit and each of the plurality of memories for (1) receiving the device power supply voltage indication signal from the voltage detection circuit, (2) applying the device power supply voltage indication signal to each of the plurality of memories such that the circuitry of each of the plurality of memories is configured in accordance with the device power supply voltage indication signal, and (3) supplying data of the nonvolatile memory card with respect to the voltage level of the device power supply voltage to external circuitry.

High power factor boost rectifier apparatus

Abstract: A power supply for providing a single level dc output voltage, with input power factor correction, from a wide range of ac input voltages commonly available worldwide. The power supply rectifier circuit can be configured as a full wave bridge for high line voltage inputs and as a voltage doubler for low voltage inputs. Output voltage regulation and power factor correction are accomplished by a high frequency boost circuit having two inductors connected in parallel for the low input voltage configuration and in series for the high input voltage configuration. The high frequency switching semiconductor components are connected in a series circuit which limits their voltage requirement to one-half the output voltage.

Dynamic and static voltage stability enhancement of power systems

Abstract: The static voltage stability and the dynamic voltage stability are integrated. To consider a shunt compensator and/or a more general load which is dependent on voltage, a modified criterion for the static voltage stability is developed and the system is controlled to satisfy this static stability criterion. For an accurate analysis of the dynamic voltage stability, the system model includes excitation systems, tap-changers, capacitors and power system stabilizers in addition to network equations. A parameter optimization technique with a modal performance measure is developed to determine optimal control parameters for dynamic voltage stability enhancement. >

Critically continuous boost converter

Abstract: In critically continuous boost converters used to achieve high power factor and low input current harmonic distortion, a power FET is driven by a pulse generator whose on time is essentially constant over a single line cycle. Off time is terminated when current in the inductor falls to zero and the voltage on the side of the inductor not connected to the input voltage is less that the input voltage. A delay causes turn on to occur at the minimum of the voltage ring to minimize turn on switching losses. At voltages when the input voltage is less than one half of the output voltage part of the on time, turn on occurs with negative current flowing through the FET power switch and the inductor. Part of the turn on time is used to charge the inductor current back to zero before energy can begin to flow back into the output of the converter. A correction circuit is provided which extends the on time as a function of the input and output voltage to avoid dead time around the zero voltage crossover of the sinusoidal input voltage which when rectified provides the input voltage to the converter.

Closed loop pulse width modulator inverter with volt-seconds feedback control

Abstract: A closed loop pulse width modulator (PWM) inverter (50) corrects for variations and distortion in the ouput AC voltage (52) waveform caused by non-linearities of the switching devices (S1-S6) or changes in the DC link voltage (3). A signal is generated that is a volt-seconds representation of the voltage error between a voltage command signal (25) and the actual AC output voltage (52) of the PWM inverter (50). The volt-seconds error signal becomes a controlling signal means in the closed loop of the PWM inverter (50) to regulate the output AC voltage (52) of the PWM inverter (50). Another signal that represents changes in the DC link voltage (3) also modifies the voltage command signal (25). The system will compensate for the non-linear behavior of the PWM inverter (50) due to deadtime, minimum on-times and off-times, and DC link voltage (3) variations and voltage drops across the switching devices (S1-S6), and will also allow the operation of the inverter (50) in a linear fashion for the region of operation when one or more of its phases are saturated, i.e., either fully on or fully off.

Power converter for converting DC voltage into AC phase voltage having three levels of positive, zero and negative voltage

Abstract: An apparatus for a three-level DC/AC converter, in which the width of output pulse having the same polarity as the fundamental wave of the converter output phase voltage is adjusted depending upon the DC component of a differential voltage between two DC voltages in a dipolar modulation system of the converter. Whereby, the imbalance of DC components between the two DC voltages is easily and effectively suppressed.

Dimmable high power factor high-efficiency electronic ballast controller integrated circuit with automatic ambient over-temperature shutdown

Abstract: An embodiment of the present invention is a dimmable, high power factor, high-efficiency electronic ballast comprising, on a single integrated circuit chip (300) a shunt regulator (302), a voltage reference (306), a high-temperature shutdown (316), an undervoltage lockout (304), a timer for startup and restarting (314), a variable oscillator (322), a mode control (320), an op-amp (318) for receiving a signal proportional to lamp current and for controlling the variable oscillator or the duty-cycle of pulses output in a closed-loop servo, and active power factor correction including an analog multiplier (12) for receiving an AC voltage and an AC current sample, and for multiplying these together to result in a comparison with a DC voltage. The comparison produces a control signal for a MOSFET (28) switch on a boost converter transformer (18) that actively corrects the power factor at a rate set by the oscillator.

Apparatus for limiting inrush current

Abstract: A circuit for limiting inrush current in a DC power supply is disclosed. The inrush limiting circuit should be placed between an input AC power line and a power supply input capacitor bank. A thermistor is located between the capacitor bank and the input diode bridge to limit the initial inrush current. Once the input capacitor bank is fully charged, an insulated-gate bipolar transistor or IGBT switches the rectified line voltage to a boost power factor correction converter circuit, which utilizes an inductor and diode along with a field effect transistor to boost the input to a high DC voltage. This high DC voltage blocks the thermistor through use of a diode and keeps it cold to maintain high resistance in case of a new off/on cycle. The IGBT can be replaced with a silicon control rectifier, a triac, or a field effect transistor.

Power supply control circuit for use in IC memory card

Abstract: An IC memory card used in a dual power supply voltage operation system and having a backup function is arranged to prevent destruction of data stored in an internal memory caused by an erroneous access in a non-operation-ensured voltage range between lower and higher operation-ensured voltage ranges Three voltage levels divided from an external power supply voltage by voltage dividing resistors are compared with a reference voltage from a reference voltage generation circuit to determine whether the external power supply voltage is at the lower or upper limit of the lower operation-ensured voltage range or the lower limit of the higher operation-ensured voltage range On the basis of outputs from these comparators, a memory protection signal generation circuit generates a memory protection signal to enable the memory to be protected even in the voltage range between the lower and higher operation-ensured voltage ranges

Linear load circuit to control switching power supplies under minimum load conditions

Abstract: An embodiment of the present invention is a switching power supply comprising a transformer (12) with a primary (14) and two secondaries (16,18), a switching transistor (20) in series with the primary, a rectifier (22) and filter (24) on one secondary to provide regulated output power, a feedback control circuit (26) that monitors the secondary (18) and adjusts the duty cycle of an on-off control signal to the switching transistor (20) to maintain a constant output at the terminals (30,32), and a monitor (34) that detects when the power level flowing through the switching regulator has dropped to a predetermined minimum and then linearly turns on a load to the transformer (12). Transistor (20) is typically a power MOSFET. The monitor (34) tracks a summing junction current before any slope compensation is added. Load (36) is a shunt regulator that is activated when the summing junction current falls below 12% of full scale. Alternatively, the predetermined value of 12% is adjustable. The shunt regulator load (36) increases the load on secondary until the summing junction current returns to 12% of full scale.

Microwave output stabilizing apparatus of a microwave oven and a method thereof

Abstract: A microwave output stabilizing apparatus for a microwave oven comprises a rectifier circuit for rectifying power from an AC power supply into a constant DC voltage; an invertor circuit for generating a high frequency power supply by controlling the DC voltage at an intermittent output state; a high voltage transformer for stepping up the high frequency power supply; and magnetron drive circuit for rectifying the high frequency power supply and oscillating a magnetron. Also, an inverter control circuit detects the current flowing into the primary winding of the high voltage transformer, converts the detected current into a corresponding voltage, the corresponding voltage with a reference voltage, and controls the inverter circuit according to the results of the comparison. Further included are an anode current detecting circuit for detecting the anode current of the magnetron and converting the detected anode current into the corresponding voltage; and, a reference voltage adjusting circuit for evaluating the anode current and changing the reference voltage of the invertor control circuit in accordance with the results of the evaluation.

Full shunt boost switching voltage limiter for solar panel array

Abstract: According to the present invention a bus voltage limiter is connected between a photovoltaic solar panel array and a load to limit the output voltage to a fixed dc reference voltage. The limiter includes a pulse width modulator which controls the duty cycle of a power switch from 0% to 100% to maintain a substantially constant output voltage V ref . A coupled inductor type boost DC to DC converter includes a pair of main windings which cooperate with the duty cycle modulated power switch to provide the output voltage. An auxiliary winding provides input ripple current cancellation in conjunction with a second inductor and a dc blocking capacitor.

Bandgap voltage reference generator.

Abstract: A bandgap voltage generator using a simple bandgap voltage reference supply circuit which has virtually no power supply rejection ratio (PSRR) which can produce an output bandgap voltage, V BG , using an extremely low power supply voltage, V DD . In order to increase the PSRR, a signal generated by the bandgap voltage reference supply circuit is amplified by a high gain amplifier circuit comprised of two cascode connected FETs. The highly amplified signal generated by the high gain amplifier circuit drives a voltage regulator, comprised of an FET used as a voltage controlled current sink, which regulates the voltage supplied from the power supply, V DD , to the bandgap voltage reference supply circuit. This combination of a bandgap voltage reference with virtually no PSRR and a high gain amplifier results in a bandgap voltage generator with a very high PSRR.

Substrate bias generating circuit

Abstract: A substrate bias generating circuit (20) provides a substrate bias voltage to a substrate (50) of an integrated circuit. A voltage-to-current converter circuit (22) provides a constant current proportional to a bandgap generated reference voltage. P-channel transistors (34 and 35) then provide constant current sources for a voltage level sensing circuit (36) based on the bandgap generated reference voltage. The voltage level sensing circuit (36) monitors the level of the substrate bias voltage, and when the substrate bias voltage reaches a predetermined voltage level, provides a first control signal for activating an oscillator (47). A level converter (43) is provided to amplify, or level convert the first control signal for more reliable control of the oscillator. A substrate bias generating circuit (20) provides a precisely controlled substrate bias voltage to the substrate (50) that is independent of process, temperature, and power supply variations.

Analysis and design of weighted voltage-mode control for a multiple-output forward converter

Abstract: A power stage model of a multiple-output forward power converter with weighted voltage-mode control is derived incorporating all the major parasitics. The model is employed to identify the feasible region of the weighting factors to meet given DC regulation specifications. A design procedure that determines the optimal selection of the weighting factors is proposed. The DC model and the design procedure are verified on an experimental two-output forward converter. >

Control circuit responsive to its supply voltage level

Abstract: In an integrated microcircuit device the supply voltage is monitored by a pair of threshold detector logic circuits configured to generate a first control signal when said supply voltage crosses over a minimum level, and a second control signal when said supply voltage crosses over a maximum level. The control signals are used to configure the device into distinct modes of operation, whereby the functions of the device and the voltage level of the power supply applied to them during testing or operation may be controlled by varying the supply voltage.

Integrated circuit device having step-down circuit for producing internal power voltage free from overshoot upon voltage drop of external power voltage

Abstract: A dynamic random access memory device is equipped with an internal power supply system for selectively distributing a step-down power voltage to internal component circuits, and the internal power supply system comprises a feedback loop for regulating the step-down power voltage on an internal power supply line to a reference voltage, a voltage detecting circuit monitoring an internal power voltage line to see whether or not the step-down power voltage is decayed to a critical level for producing a gate control signal, and an auxiliary variable load transistor coupled between the external power supply line and the internal power supply line and responsive to the gate control signal for supplementing current to the internal power supply line, wherein the critical level is inversely proportional to the external power voltage while the external power voltage is higher than the reference voltage, thereby preventing the step-down power voltage from undesirable overshoot upon production of the gate control signal.

Automatic gain selection for high power factor

Abstract: A high power factor regulator circuit which includes a variable multiplier, permitting the high power factor regulator circuit to be used with a number of input line voltage levels In one embodiment a comparator determines the multiplication or gain factor to be applied in a control loop by comparing the rectified AC input voltage to a predetermined threshold value

Wide range power supply for integrated circuits

Abstract: A wide range power supply for integrated circuits includes a voltage-down converter to receive the input supply voltage and generate a controlled low voltage signal. The circuit also includes a voltage-up converter which receives the controlled low voltage signal to generate a high voltage signal for high power circuits. Finally, a substrate bias generator is employed in the circuit to generate a substrate bias signal. Because the low power voltage is controlled, the high power voltage and the substrate bias signal are independent of any variations in input supply voltage. In alternate embodiments, the voltage-up converter or voltage-down converter can be disabled if the external supply voltage is controlled and maintained in at high or low voltage respectfully.

Voltage control of parallel operated self excited induction generators

Abstract: Two methods of analysis are proposed for use in the control of the common bus voltage of any number of parallel self-excited induction generators (SEIGs) under steady state balanced conditions. The methods are general and can be used for a single SEIG or a group of SEIGs employing similar or different machines with equal or unequal prime mover speeds. Theoretical predictions of the two models have been verified experimentally. Using these methods, effects of various parameters on the voltage control characteristics are examined for a number of cases employing similar and different SEIGs at equal and unequal speeds. >

Inverter power supply

Abstract: An inverter power supply operating at a high efficiency to provide an AC voltage to a load. The power source includes a DC voltage source and an output transformer with a primary winding, secondary winding, and a feedback winding. An FET is connected in series with the primary winding across the DC voltage source. The primary winding is connected to a capacitor to form a L-C resonant circuit which, in response to the switching of FET, provides across the primary winding an oscillation voltage to be applied through the secondary winding to drive a load, while inducing a feedback voltage across the feedback winding. The oscillation voltage is allowed to go negative at a point between FET and the primary winding. A biasing capacitor is connected to apply an offset voltage which is additive to the feedback voltage so as to give a bias voltage to FET. The power supply is characterized to include a level detector which issues a zero voltage signal when the oscillation voltage is detected to lower to at least zero level, and to include a pulse generator which, in response to the zero voltage signal, produces a pulse of a predetermined pulse-width which overrides the feedback voltage in such a manner as to enable FET to turn on for a ON-period determined by the pulse-width only after the oscillation voltage is lowered to at least zero level, whereby avoiding FET from flowing a current while the oscillation voltage is still positive and therefore reducing a switching loss.

Low-battery state detecting system and method for detecting the residual capacity of a battery from the variation in battery voltage

Abstract: There is provided a low-battery detection reference voltage table for memorizing the correspondence between current values and low-battery detection reference voltage values, which is obtained from battery voltage characteristic curves corresponding to different current values. Further, there is provided a low-battery reference voltage correction table for correcting the low-battery detection reference voltage in accordance with a voltage variation. Referring to the low-battery detection reference voltage table on the basis of the value of current output from the battery, the low-battery detection reference voltage corresponding to the current value is obtained. The voltage variation is found from the currently measured battery voltage and the previously measured battery voltage which is memorized. On the basis of the voltage variation, the correction voltage is found with reference to the low-battery reference voltage correction table. The found correction voltage is added to the low-battery reference voltage, thereby correcting the low-battery reference voltage. When the measured battery voltage is lower than the corrected low-battery detection reference voltage, the low-battery stated is determined.