Showing papers on "Voltage regulation published in 1991"

A method to compute reactive power margins with respect to voltage collapse

Abstract: A method of computing the reactive power margin-i.e. the difference between the maximum reactive load and the corresponding base case value-for a given set of load buses of a power system is proposed. This margin is aimed at assessing the system robustness with respect to voltage collapse. The corresponding collapse point is directly obtained as the solution of an optimization problem with the load increase as the objective, the nonoptimized loads as equality constraints, and the generator reactive limits as inequality constraints. The CRIC electrical decoupling yields a voltage-only problem. The latter is solved using the Newton approach and a procedure is given to deal with the inequality constraints efficiently. A simple illustrative example and simulation results obtained on the Belgian 520-bus, 41-generator system are given. >

Switching regulator circuit using magnetic flux-sensing

Abstract: Control circuits for a switching voltage regulator circuit which uses magnetic flux sensing are provided. These circuits can be used to improve output voltage regulation by reducing parasitic effects inherently present in magnetic flux-sensed feedback switching voltage regulator designs.

High power-factor converter for motor drives and power supplies

Abstract: A high power-factor converter (50) for use with motor drives and power supplies. A first and "buck"-type converter section (62) is connected to an a.c. voltage source. This section provides an output voltage having preselected voltage characteristics. This section is operational during that portion of an input voltage cycle in which the input voltage level exceeds that of the output voltage level. A second and "boost"-type converter section (70) is also connected to the voltage source. This second section also provides the output voltage, and is operational during that portion of the input voltage cycle in which the output voltage level exceeds that of the input voltage level. A control circuit (66) is responsive to the relative levels of the input and output voltages to operate the first and second converter sections on a time sharing basis in which converter operation is switched between the two converter sections as a function of the sensed actual output voltage characteristics compared to the preselected characteristics. This permits the converter to maintain a nearly full conduction angle, and therefore a high power factor, for any level of output voltage in a range from zero volts to voltage levels higher than the peak input voltage level.

Load current sharing circuit

Abstract: A load current sharing circuit is disclosed that allows multiple independent power modules, either switching or linear, to be connected in a parallel configuration such that each module delivers only its proportionate share of the load current. Each module measures the common output voltage, compares that voltage to an internal reference voltage signal, and generates an error voltage signal to be used as feedback for regulating its output voltage. The internal reference voltage signal is a function of the extent to which the current within each module differs from the current of the module with the highest current. That module functions as the master, and all the other modules act as slaves. Each slave increases its share of the load current so as to asymptotically approach the load current of the master to within a preset offset voltage, while the load current of the master decreases.

Simple topologies for single phase AC line conditioning

Abstract: This paper presents a variety of single phase AC line conditioning approaches. The topologies use a minimal number of devices and feature buck-boost voltage regulation capability without a transformer, while preserving a neutral connection which is common with the input AC line. The simplest form of the converter is seen to be an AC voltage regulator with output voltage range of 0-2 p.u. with reasonable line current waveform. Modifications allow the circuit to operate with fully controlled input current. The circuit can be further extended to provide significant ride-through capability without using a battery. Finally, a full function single phase UPS can also be realized if required. The paper contains analytical, simulation and experimental results. >

Parallel processing inverter system

Abstract: A novel method of instantaneous voltage and power balance control of a parallel processing inverter system is proposed. It consists of a high-speed switching PWM (pulsewidth modulated) inverter with an instantaneous current minor loop controller, a voltage major loop controller, and a power balance controller. This system realizes the following functions with only one inverter: constant AC output voltage control with reactive power control, active filtering to absorb load current harmonics, DC voltage and current control as AC-to-DC converter, and uninterruptible power supply (UPS) for stand-alone operation. This system covers a wide application range, including UPS systems, new energy systems, and active filters with voltage control functions. >

An integrated circuit with improved on-chip power supply control

Abstract: An on-chip power supply regulation system for a VLSI circuit such as a dynamic RAM is disclosed. The system includes a high power supply voltage detection circuit (9) and a power supply clamp circuit (7), where a clamped voltage generated by the clamp circuit biases the functional circuitry when the high power supply voltage detection circuit detects an overvoltage condition. The bias voltage applied to the functional circuitry in the normal operating condition can be a regulated voltage generated from the power supply voltage. Further included in the disclosed circuit is a burn-in voltage generation circuit (5) and a burn-in voltage detection circuit (15) which can apply an accelerated voltage which depends upon the applied power supply voltage, when the power supply voltage is higher than during normal operation but lower than in the overvoltage condition enabling the clamp operation. A multiplexer (11) connects the regulated voltage, the clamped voltage, or the accelerated voltage, to the circuit depending upon the level of the external power supply voltage. In this way, the offset between the accelerated voltage and the external power supply voltage can be optimised independently from the power supply voltage at which the accelerated voltage is enabled.

Maximum power regulated battery charger

Abstract: An AC adapter that allows a lower power rating while still providing the necessary power to a load which is substantially constant over a varying voltage range and to charge a discharged Ni-Cad battery in a desired time. The AC adapter regulates its output power to a maximum level just greater than the maximum of the load rather than providing a controlled current until a predetermined fully charged voltage is attained. In this manner, the output voltage and current are allowed to vary inversely with respect to each other in order to maintain the desired power level, allowing the output current level to be reduced as the voltage level increases. A regulated voltage mode is also provided to keep the output voltage from rising above a predetermined maximum level should the Ni-Cad battery be disconnected. One preferred embodiment includes a regulated current mode wherein the current through the Ni-Cad battery is maintained at the desired trickle level once the battery is fully charged.

Method and apparatus for voltage regulation depending on battery charge

Abstract: The method of regulating a voltage produced by a generator with a voltage regulator according to a battery charge state includes providing a controller containing a clock and a memory able to store battery and power supply reference data, battery voltage and generator rotation speed; maintaining a regulated voltage produced by the generator at a normal value (UR) during a first time interval (t1); measuring a battery voltage (UB) and decreasing the regulated voltage (UR) during a second time interval (t2); determining the battery charge state from the measured battery voltage (UB) according to the stored battery- and power supply-reference data; and, when the battery charge state is determined to be unsatisfactory, determining an additional time interval (t4) with the controller and an amount of increase of the regulated voltage (UR) sufficient to obtain a satisfactory battery charge state during the additional time interval (t4) without damaging the voltage sensitive components of the voltage regulator; and increasing the regulated voltage above the normal value (UR) by the thus determined amount and turning on no voltage-critical consuming device during the additional time interval (t4). A voltage regulator including the controller is also described.

Inverse dual converter for high-power applications

Abstract: An inverse dual converter circuit (20) provides continuous voltage step-up or step-down control over a wide range and without the need of a transformer. The converter comprises an input DC voltage source (22) for generating an input DC voltage. An inverse dual converter bridge receives the input DC voltage and comprises a network of source voltage converters (26), an AC link circuit (28), and a network of load voltage converters (32). The source voltage converters (26) and load voltage converters (32) operate at the same frequency, but at a different phase. The AC link circuit (28) stores energy to be transferred from the source voltage converters (26) to the load voltage converters (32) and supplies reverse voltage bias for commutation. The inverse dual DC-DC (20) converter may include circuitry (180) for controlling the output DC voltage and for regulating output current continuity. Topological variations of the basic circuit include transformer coupled (140), multi-phase (80) and multi-pulse derivations. The single-phase inverse dual converter circuit (20) offers a buck-boost operation over a wide range without a transformer, bi-directional power flow, and complimentary commutation of converters. The commutation mechanism provided in the inverse dual converter circuit (20), when combined with gate turn-off switch thyristors provides zero current switching. This allows operation at high frequencies in high-power applications, with high efficiency.

Method for detecting low battery state without precise calibration

Abstract: A portable electronic system, which can accurately predict impending battery failure, without using expensive comparators, by using voltage and current measurements to determine the source impedance of a battery. Preferably two banks of batteries are used, with a load-switching relay; the voltage and current of both banks is monitored, so that voltage drop under load can be monitored. Alternatively, the voltage variation of a single battery bank can simply be correlated to the current drawn by a changing load.

Delay device including generator compensating for power supply fluctuations

Abstract: A semiconductor delay device is disclosed which allows a delay time to be fixed irrespective of a power supply voltage. The semiconductor delay device includes a first switching circuit, a second switching circuit, a capacitor an N channel transistor and a control voltage generation circuit. The first switching circuit switches in response to an input signal. The capacitor is charged and discharged in response to an output of the first switching circuit. The second switching circuit switches when a voltage level of the capacitor exceeds a fixed voltage. The control voltage generation circuit generates a voltage signal appropriately proportional to a square root of the power supply voltage and applies the generated voltage signal to a gate of an N channel transistor. The N channel transistor is connected between the first switching circuit and the source and current drivability of which is changed in response to the voltage signal. As a result, a delay time can be fixed irrespective of a power supply voltage.

Voltage converter of semiconductor device

Abstract: In a voltage converter provided in a semiconductor device and supplying an internal supply voltage to a circuit in the semiconductor device, a circuit is provided for generating a first voltage whose dependency on an external supply voltage is regulated to a predetermined small value, while another circuit is provided for generating a second voltage whose dependency on the external supplying voltage is larger than the dependency of the first voltage. Another circuit selects the first voltage when the semiconductor device is in a state of a standard operation and selects the second voltage when the device is in another state of operation, such as testing or aging. The selected voltage may be converted by a differential amplifier which is constituted by a load of P-channel MOS transistors and a source-coupled pair of N-channel MOS transistors. An output of the differential amplifier is fed back through a directly coupled voltage lowering circuit which generates the converted output.

Data driver circuit of liquid crystal display for achieving digital gray-scale

Abstract: A data driver circuit of TFT-LCD having a plurality of power source voltage terminals with different voltage levels, an output terminal for providing a voltage to the TFT-LCD, a plurality of analog switches with load resistances provided between one of the source voltage terminals and the output terminal and having a switching terminal, and a voltage selection circuit for transmitting an ON signal to a selected one or more of the respective switching terminals of the analog switches. When an individual analog switch is turned ON, the corresponding source voltage value is supplied to the output terminal of the driver circuit and when two or more analog switches are selectively turned on, a combination of the voltage levels of the respective source voltage is associated with those switches which are turned ON is produced as the driver circuit output voltage, thereby affording a greater number of gray levels as the driver circuit output voltage levels than the number of power source voltage levels.

Voltage supply circuit for use in an integrated circuit

Abstract: The invention relates to a voltage supply circuit used in a semiconductor integrated circuit wherein switching between voltages generated is carried out in dependency upon whether the circuit is in an ordinary operating state or in a standby state. This voltage supply circuit includes a first reference voltage generator for supplying a reference voltage through an amplifier circuit to an internal circuit in the operating state, and a power supply voltage converter for supplying a voltage to the internal circuit at least in the standby state, wherein a second reference voltage generator provided independently of the first reference voltage generator becomes operative for a transient time period during which the second reference voltage generator shifts from the standby state to the operating state. By the action of the second reference voltage generator, a setup time at the time of start of the operation is shortened. Further, by allowing the first reference voltage generator to be inactive in the standby state, low power consumption is realized.

Multivariable self-tuning regulator for load frequency control system with interaction of voltage on load demand

Abstract: This paper presents a new method of designing a multivariable self-tuning regulator for a load frequency control system with the inclusion of interaction of voltage on load demand. The self-tuning controller through speed governor control and excitation control is derived by defining a cost function with a term for presenting the constraints on the control effort, and then by minimising it with respect to the control vector. The proposed method is applied to a two-area power system provided with nonreheat turbines in which the interaction of voltage deviation on load demand is considered, and the control effects of this regulator are examined using digital simulation.

Power supply tracking regulator for a memory array

Abstract: A voltage regulator is provided for controlling an on-chip voltage generator which produces a boost voltage across a charge reservoir for supply to one input of a plurality of word line drivers in a memory array. The regulator is configured such that the charge reservoir voltage will track the power supply voltage and the difference between the power supply voltage and the charge reservoir voltage will be maintained substantially constant over a predefined power supply range. The voltage regulator includes a bandgap reference generator, a first differential circuit for producing a transition voltage from the reference voltage and the power supply voltage, a first transistor for comparing the power supply voltage with the boost voltage, a second transistor for comparing the transition voltage with the reference voltage and a latching comparator for equating the signal outputs from the first and second transistors so as to define a control signal for the on-chip voltage generator. Along with further specific details of the voltage regulator, a preferred bandgap reference generator is described.

Programming voltage generator circuit for programmable memory

Abstract: Electrically programmable memories often include an internal circuit for establishing a programming voltage Vpp higher than the supply voltage. This circuit is formed by a charge pump followed by a voltage regulator. Previously, an analog circuit was usually provided behind the regulator to convert the level of voltage Vpp, set up by the charge pump, into a signal with a slow-rising edge (to reduce the constraints on the programmed cells and increase their lifetime). Instead of such analog circuit, the present invention provides a digital control circuit to control the regulator to set up a regulation voltage that rises gradually from a low value up to the desired value Vpp. The digital control circuit comprises counter with k outputs which enables the gradual short-circuiting and unshort-circuiting of the various series-mounted transistors constituting the regulator, thus making the regulation voltage increase slowly.

Implantable medical devices employing capacitive control of high voltage switches

Abstract: An implantable device for treating a malfunctioning heart is disclosed. The device includes a high voltage circuit having a tank capacitor for storing therein during a charging mode of operation thereof high voltage DC electrical energy and for delivering such energy to a malfunctioning heart in the form of an electrical shock during a discharging mode of operation thereof. The device further includes a high voltage switch coupled to the high voltage circuit for switching, in the order of microseconds, the high voltage circuit between its charging and discharging modes of operation; a power supply for providing low voltage electrical energy for use in controlling the high voltage switch; a control circuit coupled between the power supply and the high voltage switch and capable of driving the high voltage switch to switch its output in the order of microseconds, for controlling the operation of the high voltage switch; and capacitors for capacitively coupling the power supply to the control circuit and electrically isolating the high voltage DC electrical energy from the power supply. The control circuit includes a common mode switch for rejecting common mode noise, and an additional switch for rapidly changing the output state of the high voltage switch.

AC line current controller utilizing line connected inductance and DC voltage component

Abstract: A controller for controlling currents in an AC line connected to the controller is capable of causing the controlled current to assume any pre-determined magnitude and wave form. The pre-determined AC magnitude and wave form need not be of the same frequency or wave form existing at AC power lines connected to the controller. The controller uses the voltage at the AC power lines and an additional DC voltage as two sources of power to control the current in an inductor connected in series with the AC lines. A plurality of electronic switches are arranged so that at any instant in time, closing of appropriate switches will apply either the line voltage, or the sum of the line voltage and the DC voltage, or the difference between the line voltage and the DC voltage to the inductor. This causes the current of the inductor to increase or decrease at a rate determined by the net applied voltage. Because of the two sources of power, either a positive or negative voltage is available at any time for connection to the inductor. Modulation of the switches provides a time varying average voltage across the inductor that results in the desired time varying inductor current which, due to its series connection is also the AC line current. Applications of the controller include control of power factor, at unity or any desired lagging or leading level, neutralizing of harmonic line currents, and recovery of power generating externally of the controller by feeding regenerative current back to the AC power lines.

Integrated semiconductor memory with internal voltage booster of lesser dependency on power supply voltage

Abstract: A word-line drive voltage generation circuit for use in a dynamic random-access memory is disclosed which is connected to a word line via a row decoder including MOS transistors The circuit includes a charge-bootstrap capacitor having insulated electrodes, one of which is connected to a first reference voltage generator via a switching MOS transistor, and the other of which is connected via a MOS transistor to a second reference voltage generator These voltage generators provide the capacitor with the constant dc voltage that are essentially insensitive to variation in the power supply voltage for the memory The resultant word-line drive voltage may thus be free from variation in the power supply voltage during the operation modes of the memory This enables the word-line voltage to be high enough to allow successful "H" level writing at a selected memory cell without creation of any unwantedly increased dielectric breakdown therein, in the entire allowable range of the power supply voltage

Method and apparatus for reduced power integrated circuit operation

Abstract: A battery-powered electronic system in which ICs of low and high voltage specifications can be operated simultaneously by a single low voltage power supply, wherein prolongation of battery life, miniaturization of the housing size and reduction of manufacturing costs are achieved. The present invention comprises a monolithically integrated charge pump circuit for boosting a power supply voltage so as to output a voltage greater than that of the power supply voltage, and a power supply multiplexor for selecting between the output of the charge pump circuit and the power supply voltage in accordance with a power supply select control signal. The output of the multiplexor is used as a supply voltage, for at least one other IC in the system. The voltage selection process is dynamically determined based on the time-varying requirements of system operation. A voltage regulation circuit may be used to provide control over the charge pump circuit output. Circuitry is disclosed for disabling charge pump operation, when such operation is unnecessary, to reduce power consumption.

Electrical power monitoring system

Abstract: A method and system incorporating an integral power consumption monitor-circuit breaker panel for industrial or commercial buildings and facilities. The power consumption monitor-circuit breaker panel not only protects each end use within the building against harmful overloads, but also monitors peak power demands of each end use. Electrical current, voltage and phase information is provided by each monitor-breaker. This information is then fed to a processing circuit that provides a power consumption value. The power consumption value is then fed to recording device to provide a power consumption history for each end use. Each monitor-breaker is identified by its end use, as for example, by color coding. The monitor device of each circuit breaker is designed to provide a voltage that is proportional to the circuit load. Two methods may be used to provide such a voltage signal: a) the voltage signal can be developed across a built-in shunt in each circuit braeker; and b) a proportional voltage can be obtained by use of a circuit breaker with a built-in Hall effect device, wherin the product of the instantaneous current and voltage along with the phase angle between them, provides the power measurement. The current and/or instantaneous power information can be sent to the recording device via a powerline carrier, radio link, or optical fiber. The information can be integrated to provide either kW or kW/hr readings.

X-ray power supply utilizing A.C. frequency conversion to generate a high D.C. voltage

Abstract: An output voltage of an A.C. power source is input to an frequency converter and the frequency thereof is increased. A plurality of high voltage transformers of small capacity each of which has a secondary winding of a small number of turns and which are connected in parallel with one another are connected to an output terminal of the frequency converter. Outputs of the high voltage transformers are respectively connected to high voltage rectifier circuits. Outputs of the high voltage rectifier circuits are serially coupled, the output voltages thereof are added together, and the addition result is applied to an X-ray tube. Combinations of the high voltage transformers and the high voltage rectifier circuits are molded into units one or a preset number at a time with solid insulating material including gel insulating material.

Enhanced synchronous rectifier

Abstract: A power converter is provided located in a remote terminal of a telephone system, the telephone system having a central office which powers a plurality of telephone loops with a DC voltage having at least two substantially different levels The remote terminal power converter derives remote terminal output load voltages including a low voltage regulated supply from the DC voltage provided to the loop from the central office The remote terminal power converter comprises a synchronous rectifier for providing a predetermined low voltage regulated supply The remote terminal power converter further comprises a receiving circuit connected to the loop for receiving DC voltage from the central office and supplying a low voltage output for producing the low voltage regulated supply A switch is associated with the receiving circuit for producing an output signal on the low voltage output, the output signal having sequential charging, flyback, and discontinuous intervals The discontinuous interval has a variable time duration dependent on at least the voltage level being coupled to the loop by the central office The synchronous rectifier is coupled between the low voltage output and the low voltage regulated supply and includes a power switching device, and a circuit responsive to the termination of the charging interval for driving the power switching device on The synchronous rectifier also includes a circuit for sensing a condition indicative of the onset of the discontinuous interval and turning off the power switching device for at least the duration of the discontinuous interval, independent of the time duration of the discontinuous interval

Constant voltage generation of semiconductor device

Abstract: A constant voltage generator of a semiconductor device includes an oscillator for generating an AC signal, a charge pump for pumping charge from a power voltage supply line by a predetermined pumping ratio in accordance with the AC signal of the oscillator, a charge storage capacitor for storing the pumped charge, and a voltage limiter for limiting the voltage across the charge storage capacitor at a predetermined voltage level, then outputting a constant voltage. According to the present invention, the charge of the storage capacitor is quickly stored, a constant voltage is obtained independent of a power source voltage, and the reference voltage output can be greater than the power source voltage.

Circuit for generating internal supply voltage

Abstract: An internal supply voltage generator receiving an external supply voltage, generates a stable, constant internal supply voltage to be applied to a semiconductor memory device regardless of the variation of the temperature. For this end, the generator includes a voltage sharing circuit (80) which has a first variable resistor (R1 ') with higher resistance as a load element and a second variable resistor (R2 ') with lower resistance as a driving element. As the temperature increases, the resistance of the first variable resistor (R1 ') increases, thereby decreasing the current flow formed therethrough. Then, the comparator (60) connected to the output of the voltage sharing circuit (80) allows the output circuit (70) to increase the internal supply voltage, in response to increase of the temperature.

Harmonic analysis of systems with static compensators

Abstract: Static VAr compensators with thyristor-controlled reactors generate harmonics. Due to the voltage regulation characteristics of the compensator, the generated harmonics depend on unknown thyristor firing angles and the network load flow conditions. The inclusion of load flow dependent firing angle determination in the author's computer-based multiphase harmonic load flow (MHLF) technique (see ibid., vol.6, no.1, p.174-82, 1991) is described. It uses a novel conduction angle adjustment scheme. This general and simple scheme can easily be used for the analysis of other nonlinear elements with control characteristics. Various case studies are presented to demonstrate the performance and application of the technique. Field test comparisons are included. >