Showing papers on "Voltage regulator published in 1988"

A posturing strategy against voltage instabilities in electric power systems

Abstract: The problem of system collapse or blackout characterized by a local severe voltage depression is generally believed to be associated with inadequate VAR support at key busses. The authors discuss techniques for improving the system security with respect to this index. The effect of adding capacitors are examined. They also present a continuation technique that redistributes the system generation to the optimal operating condition with respect to the minimum singular value index. >

Transformerless DC-to-DC converters with large conversion ratios

Abstract: A novel switching DC-to-DC converter is introduced in which large voltage step-down ratios can be achieved without a very small duty ratio and without a transformer. The circuit is an extension of the Cuk converter to incorporate a multistage capacitor divider. A particularly suitable application would be a 50 V to 5 V converter in which DC isolation is not required. The absence of a transformer and a larger duty ratio permits operation at a high switching frequency and makes the circuit amenable to partial integration and hybrid construction techniques. An experimental 50 W three-stage voltage divider Cuk converter converts 50 V to 5 V at 500 kHz, with an efficiency higher than that for a basic Cuk converter operated at the same conditions. A corresponding voltage-multiplier Cuk converter is described, as well as dual buck-boost-derived step-down and step-up converters. >

MW/voltage control in a linear programming based optimal power flow

Abstract: A functional improvement to the linear-programming-based optimal power flow technique is reported. The new feature allows the rescheduling of the active power controls to correct voltage-magnitude-constraint violations. It preserves the reliability and speed characteristics of the traditional linear programming approach. Results demonstrating the effectiveness of the method on a small and a large power system are presented. >

Power conversion distribution system using a high-frequency AC link

Abstract: A power conversion system configuration based on a 20 kHz single-phase voltage link is proposed for systems having distributed power requirements. The proposed configuration permits flexibility in the choice of voltage levels in the system without the penalty of bulky magnetic components, has fast system response, high efficiency, and freedom from acoustic noise, and provides a high degree of uniformity and ease of implementation. A zero-voltage switching pulse-density-modulated converter is proposed as the basic interface converter. It is shown that the technique of pulse-density-modulation allows low distortion synthesis of fixed- or variable-amplitude DC and fixed- or variable-frequency, single- or three-phase AC from the half-cycle pulses of the link voltage. A breadboard system has been built to experimentally verify the models and to complement the theoretical work. >

Secondary voltage control using pilot point information

Abstract: The authors study the minimal information structure needed for monitoring and control of the voltage profile and the reactive power flow of a power system. Emphasis is on the minimum amount of information (data) required for reliable decision-making. An effort is made to work with fewer voltage data and therefore make the real-time monitoring and control more manageable. An annealing algorithm for selecting pilot points is presented. These are the load buses at which the voltage is to be measured in real time. Simulation results obtained with the algorithm for the Central Illinois Light Company system are presented. >

Performance characterization of a new discrete pulse modulated current regulator

Abstract: A novel discrete pulse-modulated current regulator, which controls a space vector that describes the load current, is introduced. This controller uses no additional state feedback and results in better performance than the current regulated delta modulator (CR Delta M). The proposed adjacent state discrete time current regulator, which switches between adjacent switching vectors and the zero state on the basis of the state chosen by the CR Delta M scheme, contains most of the operating characteristics of a cost function regulator, which utilizes full state feedback. Simulation results of this new regulator are compared to the CR Delta M and the cost function discrete time current regulator. The same ideas used in the discrete pulse case can be extended to form a new hard-switched hysteresis-type current regulator. In either case, the regulator is easily implemented, requiring no calculation of counter-EMF (electromotive force) or Delta I. In addition, a modified sigma/delta modulated voltage regulator that satisfies the pulse polarity consistency rule is derived. Finally, complete experimental results are given. >

An experimental large-capacity semiconductor file memory using 16-levels/cell storage

Abstract: A 4-bit semiconductor file memory using 16-levels (4-bits)/cell storage is described. The device has 1-Mb single-transistor dynamic memory cells which are divided into 4-kb sequential-access blocks. It incorporates a staircase-pulse generator for multilevel storage operations, a voltage regulator to protect against power-supply voltage surge, and a soft-error-correction circuit based on a cyclic hexadecimal code. The device is fabricated using 1.3- mu m CMOS technology. It operates with a 5-V single power supply. Random block selection time is 147 mu s, while the sequential data rate is 210 ns. A single-incident alpha particle destroys 4-bit data in two or more adjacent cells. The error correction circuit completely corrects these errors. The soft-error rate under actual operating conditions with error correction is expected to be under 100 FIT (10/sup -7/ h/sup -1/). >

Voltage multiplying and inverting charge pump

Abstract: A charge pump circuit and associated method is provided for outputting either a positive or a negative output voltage, or both, which each may have a predetermined magnitude which is an integer multiple of the magnitude of a power supply voltage used to power the circuit. In one form, a first capacitor is charged to the power supply voltage. The first capacitor is coupled to the power supply voltage to develop a double voltage transfer supply with the supply voltage. Second and third capacitors are charged by the double voltage transfer supply. The second capacitor is used to store the charge from the first capacitor for a continuous output voltage having a magnitude which is twice the magnitude of the power supply. The third capacitor may be reconfigured to generate a negative transfer voltage. The negative transfer voltage is used to charge a fourth capacitor which provides a negative output voltage with twice the magnitude of the power supply voltage.

A high performance control method of a voltage-type PWM converter

Abstract: A high-performance control method for a voltage-type pulsewidth-modulated voltage-type converter is introduced. Starting from the modeling of the converter, power-factor control and five types of DC voltage control are discussed. The stability and responses of these control methods are analyzed and compared with the root locus method and by digital simulation. The most promising approach, which uses current feedforward control, is applied to the drive test of an induction motor, and its excellent performance is confirmed. >

Stabilized power supply unit

Abstract: A stabilized power supply unit designed to supply the power from the commercial power source as far as the commercial power source is normal but supply the power from a battery that can be made available by an automatic switching device when the commercial power source has failed, wherein the AC voltage from the commercial power source is rectified by a rectification circuit to obtain almost equal DC currents on both the positive and negative sides of the common line while the commercial power source is normal. Said DC voltage is chopped by the boosting chopper circuit to boost the voltage on both the positive and negative sides. The boosted voltage is converted into the AC voltage through the DC-AC inverter, and the high-frequency component of the AC voltage is compressed through the filter in order to be outputted as an AC voltage of specified frequency. When the AC voltage is not inputted due to the failure of the commercial power source, the DC voltage from the battery is applied to the DC-AC inverter in order to be converted into the AC current and outputted as the specified AC voltage through the filter. In this manner, the direct transmission circuit with a common line can be formed without including an isolation device.

High voltage semiconductor with integrated low voltage circuitry

Abstract: Low voltage semiconductor devices (2′,3′) are integrated monolithially with a high voltage semiconductor device (1′) on an electrically conductive substrate. The substrate forms an electrode (4′ of the high voltage device (1′) and is connected in use to the high voltage terminal (5′) of a power supply. The low voltage devices (2′,3′) operate from a regulated low voltage supply (12′,13′), which is regulated with reference to the high voltage supply voltage, and not with reference to earth. This reduces the need to isolate the low voltage devices from the conductive substrate. An intelligent power switch circuit constructed in accordance with the invention is suitable for example for use in a motor vehicle.

High-efficiency programmable power supply

Abstract: A high-efficiency programmable power supply including a linear regulator and a switching pre-regulator. The switching pre-regulator monitors the voltage drop across the series pass regulator pass transistor and maintains a predetermined voltage drop thereacross. The programmable power supply output voltage is varied according to a digital signal applied to the linear regulator. The switching pre-regulator, in providing a generally constant voltage drop across the linear regulator pass transistor, increases efficiency of the power supply by reducing excess voltage which appears at the input of the linear series pass regulator to a minimum level below which the linear regulator can operate. Therefore, the power supply according to the present invention maintains high efficiency over a wide range of selectively programmed output voltages.

Analysis of tap-changer dynamics and construction of voltage stability regions

Abstract: The destabilizing behavior of on-load tap-changers is an important mechanism responsible for the voltage collapse of power systems. The authors use a nonlinear dynamic model of the tap-changer, impedance loads, and decoupled reactive power-voltage relations to reconstruct the collapse. Based on the proposed M-bus network model, results presented include (1) a criterion for voltage stability, (2) a method to obtain a voltage region, and (3) qualitative characterizations of the equilibria. >

Op Amps and Linear Integrated Circuits

Abstract: Building blocks of the linear integrated circuit. Ideal operational amplifiers. Real operational amplifiers. Designing with real Op Amps. Power circuits. Voltage regulators. Active filters. Signal generation and shaping. Specialized analog functions. Appendices A-D.

Power system stabilizers design using optimal reduced order models. II. Design

Abstract: For pt.I see ibid., vol.3, no.4, p.1670-5, 1988. The design of power system stabilizers using an optimal reduced-order model whose state variables are torque angles and speeds is examined. Two systems, a one machine-infinite bus system and a multimachine system, are considered. A controller, which is a linear feedback of these variables only and hence accounts for the realities and constraints of electrical power systems is designed based on the reduced-order model. The results obtained with the study systems demonstrate that the proposed controller is very effective. >

DC supply having low and high constant voltages for powering a polarity inverter controller

Abstract: A power supply comprises an inverter circuit for converting an input voltage from a d.c. voltage source to a desired output voltage which is maintained constant under varying current of a load circuit through the feedback operation of an inverter controller. A threshold circuit including a breakdown diode is connected to the d.c. voltage source. The base of a voltage sensing transistor is connected to the breakdown diode for switching to a conducting state when the d.c. voltage exceeds a prescribed level determined by threshold voltages of the breakdown diode and the voltage sensing transistor. A pair of current carrying transistors are connected between the d.c. voltage source and a power supply terminal of the inverter controller. Responsive to the condition of the voltage sensing transistor current is supplied through the current carrying transistors from the d.c. voltage source to the inverter controller. The source voltage supplied to the inverter controller is held at zero volt until the d.c. input voltage rises above the prescribed level and jumps to a high level which is maintained constant by a semiconductor circuit comprising the breakdown diode, the voltage sensing transistor and the current carrying transistors.

Field oriented control of an induction machine in a high frequency link power system

Abstract: A field-oriented controlled induction machine drive operating with a high-frequency single-phase sinusoidal voltage link is presented. System performance is investigated by computer simulation and is verified by test on an actual prototype system. A control loop is proposed for minimizing the link-voltage fluctuation. The capability of rapid demagnetization of the induction machine by current regulation is investigated. A new current modulation technique called switch mode selection is proposed and its performance is compared with the conventional delta modulation technique. >

Power line surge suppressor

Abstract: A surge suppressor for repeatedly protecting a load against surges occurring on A-C power mains from lightning surges or the like comprises a first series circuit having a first inductance and a first alternating voltage limiter, including at least a first capacitance and a bidirectionally conductive rectifier circuit, coupled between first and second input terminals The first inductance conducts substantially all of the current supplied from the A-C power mains A second series circuit comprising a second inductance and second alternating voltage limiter, including at least a second capacitance and a second bidirectionally conductive rectifier circuit, is coupled across the first alternating voltage limiter and is coupled to first and second output terminals The first series circuit is arranged for limiting surge currents and voltage excursions passed to the second series circuit to first levels while the second series circuit is arranged for further limiting surge currents and voltage excursions passed to the output terminals to second levels less than first levels

Stabilized low dropout voltage regulator circuit

Abstract: A voltage regulator circuit is set forth in which the series pass transistor has its high impedance (collector/drain) electrode connected to the output terminal and a shunt transistor has its low impedance (emitter/source) electrode connected to the output terminal. The circuit is arranged to ensure that the shunt transistor is always conductive so that its low impedance electrode will stabilize the operation of the circuit without requiring any external components. The circuit can be fabricated in either bipolar or CMOS form and a low dropout configuration is employed.

Apparatus for controlled switching of a microcomputer to standby mode

Abstract: A voltage regulator connected to a microcomputer is switched from main power to standby power by a monitoring integrated circuit in response to a switch off by the control circuit after receiving a switch off command, from an ignition switch, and only after the computer has been reset. The monitoring integrated circuit has a plurality of circuit elements including a circuit element which generates a control signal for switching the voltage regulator to a state producing a standby voltage which powers the microprocessor to save the information in the microprocessor memory. Preferably the circuit element generating the control signal is an operational amplifier whose output is fed by a time delay network which delays switching of the voltage regulator.

Two-part characterization of PWM voltage regulators at low frequencies

Abstract: The most widely used types of pulse-width-modulated (PWM) DC/DC converters are dynamically modeled at low frequencies in terms of two-port networks. Four DC parameters fully characterize each type of regulator. These closed-loop parameters are related to six transfer functions relevant to the open-loop circuit. Practical dynamic problems involving stability, electromagnetic cleanness, and transmission of disturbances from the load to the voltage source (and vice versa) can be solved on the basis of the formula given. >

Closed-loop performance comparisons of switching regulators with current-injected control

Abstract: The authors verify the validity of applying state-space averaging and linearization to the control law of current-injected switching regulators for designs with wideband first-order open-loop responses without right-hand plane (RHP) zeros. Quantitative closed-loop performance comparisons are made of current-injected versus voltage control for the boost and buck switching regulator topologies. In buck-topology regulators, current-injected control implemented using pole cancellation, does not yield categorically better closed-loop performance than what is obtained by using lead compensated voltage control. For the boost regulator, the advantages of current-injected control are greater since lead-compensation cannot usually be used due to the duty-factor-dependent complex pole and RHP zero. >

ESD protection circuit for MOS integrated circuits

Abstract: An ESD protection circuit, suitable for use as part of an integrated circuit, limits the voltage potential at the contacts of the integrated circuit to a voltage potential difference range relative to, though extending beyond the voltage source potentials of the circuit protected. The ESD protection is effective regardless of whether the integrated circuit is powered. The ESD protection circuit includes a clamp subcircuit for limiting the voltage potential at a clamp point to a first voltage range approximately defined by the voltage source potentials and a voltage offset subcircuit, coupled between the clamp point and an integrated circuit contact, to establish a second voltage range encompassing the first voltage range. The voltage offset subcircuit conducts current between the clamp point and the contact to limit the voltage potential at the contact to the second voltage range.

Ultrasonic oscillation circuit

Abstract: A circuit for generating a driving signal for an ultrasonic vibrating element including a voltage controlled oscillator for generating an oscillation signal which is supplied to the ultrasonic vibrating element as the driving signal, a phase difference detector for detecting a phase difference between the voltage and the current of the driving signal to produce a control voltage corresponding to the detected phase difference, said control voltage being applied to a control input of the voltage controlled oscillator, a comparator for comparing the control voltage from the phase difference detector with a reference voltage to generate an output signal when the control voltage exceeds the reference voltage, and a voltage setter for responding to the output signal to reset the oscillation frequency of the voltage controlled oscillator to a predetermined frequency which is lower than the optimum resonance frequency so that the ultrasonic vibrating element is energized in the most efficient manner.

Voltage regulator for charger/generator

Abstract: In a voltage regulator for charger/generator comprising a switching element, connected between a battery and a field winding of a generator adapted to charge the battery, for switching on and off an exciting current flowing through the field winding and a voltage detector responsive to voltage of the battery to control the operation of the switching element, there are provided an oscillator for generating an oscillation signal of a desired duty ratio, an initial excitation signal generator circuit having a plurality of stages of frequency dividers for dividing the frequency of the oscillation signal generated from the oscillator and combining together frequency division signals of the frequency dividers to produce a synthesized output signal of a desired duty ratio, a booster for boosting and rectifying an AC signal containing the oscillation signal of the oscillator and a signal which is opposite in phase to the oscillation signal to produce a boosted output signal, and excitation control means being operative, when the generator is in non-generation condition, to apply the oscillation signal of the oscillator to the booster in synchronism with the output signal of the initial excitation signal generator circuit so as to cause the booster output signal corresponding to the output signal of the initial excitation signal generator circuit to on/off control the switching element to thereby effect initial excitation of the generator and being operative, when the generator is in a predetermined generation condition, to respond to an output signal of the voltage detector so as to control the application of the oscillation signal to the booster to thereby on/off control the switching element in dependence on the battery voltage.

Temperature and power supply compensation circuit for integrated circuits

Abstract: A monolithic integrated circuit generates a programmable time delay under control of a digital work. The delay is generated by comparing a ramp signal to a threshold determined by the value of the digital word and appears as a time difference between a trigger pulse and a pulse generated when the value of the ramp voltage equals the value of the threshold voltage. The ramp voltage is generated by a simple resistance/capacitance charging circuit whose time constant can be adjusted by the user. The threshold voltage is set by a digital-to-analog converter (DAC) and resistor circuit which converts the digital control word into a variable voltage. In order to stabilize the device against changes in temperature and power supply variations, a voltage coupling circuit forces the threshold voltage to track changes in the ramp voltage caused by temperature and power supply variations. The coupling circuit obviates the need for percision voltage sources or current mirrors conventionally used to compensate for temperature and power supply changes. Without the need for the latter device, the integrated circuit can be easily and inexpensively fabricated of transistors of a single bipolar type.

Voltage regulator for AC single phase and three phase systems

Abstract: A voltage regulator for AC single phase and three phase systems. An output voltage is controlled by controlling a preset stepped addition to or subtraction from the input voltage. The controlled addition or subtraction is performed by a series injection transformer whose secondary is in series with the input voltage and whose primary is controlled by a microprocessor based switch matrix. The switch matrix imposes various voltage levels and phasing on the primary winding so as to produce a regulated system output voltage.

Solar panel output enhancement circuit

Abstract: A circuit for operation with solar panels exhibiting constant current and variable voltage characteristics. The power output of the panels is maximized by the circuit through the use of a step-down form of regulator which functions to monitor the peak voltage level of the panel and regulate with a switching type regulator in accordance therewith. Thus, peak voltage levels are maintained while current output to the load driven by the panels is enhanced. When employed for battery charging, the circuit includes a threshold selection network which identifies the nominal voltage rating of the battery under charge and provides appropriate adjustments to carry out a pulse charging technique. For start-up conditions wherein battery voltages may be below levels requisite to evaluate nominal rated voltages, a higher level charging voltage is applied for a predetermined short interval until adequate threshold is achieved to make appropriate determinations of rated voltage values. In one embodiment of the current boosting circuit, the gate capacitance of a field effect transistor type regulator switching component is taken advantage of to simplify circuit structure.

AFT circuit for CATV receiver system

Abstract: An automatic fine tuning (AFT) circuit for a CATV receiver system of a double conversion type having a first local oscillator and a second local oscillator and a first mixer and a second mixer respectively supplied with oscillation outputs from the first and second local oscillators is disclosed. A reception signal is sequentially subjected to frequency conversation by use of the first and second mixers so as to attain an intermediate frequency signal of a predetermined value. The AFT circuit includes a control voltage generator for outputting a control voltage which is a function of a frequency fluctuation of the intermediate frequency signal; a selector for selecting either the control voltage or a constant voltage and for supplying the selected voltage as an oscillation frequency control voltage controlling the oscillation frequency of the second local oscillator; an integration unit for integrating the oscillation frequency control voltage so as to produce an integrated control voltage; and a voltage comparator for comparing the integrated control voltage with a reference voltage so as to supply a result of the comparison to the selector. In response to the compare result from the voltage comparator, the selector supplies the control voltage to the second local oscillator when the integrated voltage is higher than the reference voltage and supplies the constant voltage to the second local oscillator when the integrated voltage is lower than the reference voltage.

Switching regulator having a pulse width control system

Abstract: A switching regulator includes a high frequency transformer having a primary and secondary and tertiary windings. It also has a switching element and shunt regulator and photo coupler and control circuit and these elements are arranged for controlling the on-period and the on-time of the switching element so as to increase the on-period as well as the on-time when the load is heavy. The switching losses caused by the limit of the capability of the switching element as a result of an increase in the on-period upon the load becoming light are prevented while the switching frequency is prevented from becoming an audio frequency upon the load becoming heavy. Thus, a high efficiency switching regulator with a wide range of equal load capacities may be constructed.