Showing papers on "Voltage regulator published in 1986"

Thermal cautery system

Abstract: A thermal cautery system having an endoscopically deliverable probe connected to a power supply and display unit. The power supply and display unit, when triggered by a footswitch, energizes a voltage regulator having a current limited output that supplies power to the probe. The current limiting function of the voltage regulator is disabled for a predetermined period that power is initially applied to said probe to minimize the heating time of said probe. The current through said probe is sensed and used to increase the voltage at the output of the voltage regulator as the current increases to compensate for the voltage drop in the conductors connecting the probe to the power supply. A manually selected portion of the sensed current through the probe is also integrated and used to terminate the flow of current through the probe when the integral of the current with respect to time has reached a predetermined value. A tone generator provides an audible indication when power is being applied to the probe and for a predetermined period thereafter to allow the probe to cool before the absence of the tone signals the removal of the probe from tissue being coagulated. The probe is heated by current flowing through an internal diode having a predetermined breakdown voltage at a predetermined temperature. The temperature of the probe is self-regulated by applying a voltage to the probe that is substantially equal to said predetermined voltage so that the current through the probe is reduced at said predetermined temperature.

Battery powered system

Abstract: In an exemplary embodiment, a battery conditioning system monitors battery conditioning and includes a memory for storing data based thereon; for example, data may be stored representative of available battery capacity as measured during a deep discharge cycle. With a microprocessor monitoring battery operation of a portable unit, a measure of remaining battery capacity can be calculated and displayed. Where the microprocessor is permanently secured to the battery so as to receive operating power therefrom during storage and handling, the performance of a given battery in actual use can be accurately judged since the battery system can itself maintain a count of accumulated hours of use and other relevant parameters. Where an embodiment includes a main battery and a backup battery, the voltage of each may be individually measured, and each may be conditioned. Battery capacity of each may be measured. In a unique low voltage sensing circuit applicable to power sources generally, an automatic voltage regulator may itself sense a low power condition without requiring additional precision components. As an example only, such detected low power condition may be utilized to effect switch over to a backup battery or other auxiliary power supply.

Sliding Mode Control of Power Converters

Abstract: Switched mode power converters are being used extensively for the purpose of efficient power conversion. Such converters are nonlinear, time variant systems. In the past such converters were being modelled using the state space averaging method. The theory of variable structure systems (VSS), and sliding mode control form a mutually complementary analysis and design tools for the control of switched mode power converters. The application of sliding mode control is presented for dc-to-dc converters and electrical motor drives in this thesis. The concept of sliding mode control is brought out through exhaustive examples of second order systems. The equivalent control, an analysis method of VSS, is applied to obtain transfer function description of dc-to-dc power converters. The sliding mode control is applied to the control problem of dc-to-dc power converters and speed controlled electrical drives to develop practical design techniques. The practical design methods are confirmed through experimental results.

Capacitor-plate bias generator for CMOS DRAM memories

Abstract: A capacitor-plate bias generator produces a voltage on the capacitor plate node which consists of a constant voltage plus the sense-level voltage. Consequently, the capacitor-plate node tracks any variations in the sense-level voltage. The constant voltage is 3VBG, or 3 times the bandgap voltage of silicon. The circuit includes a reference-voltage source which produces the sum of the sense-level voltage and VBG, and a feedback control circuit for enabling either a charge pump or a charge bleeder to regulate the capacitor-plate voltage at a level above the circuit supply voltage.

Charge pump voltage regulator

Abstract: A voltage regulator (11) provides a pulse width modulated voltage regulator output (40) to a drive circuit (37) to provide field coil excitation for a voltage generator (15-17) providing a charging signal for a battery (14). The voltage regulator output determines on/off states of an FET power switching device (28) coupled in series with a field coil (17) across a maximum power source voltage potential VBAT corresponding to battery voltage. The drive circuit includes a charge pump (26, 35, 36) with a low capacitance capacitor (26) coupled and decoupled across a source of voltage potential at a rate determined by a high frequency signal (41), provided by the regulator, having a frequency substantially in excess of the frequency of the voltage regulator output. The drive circuit includes a pair of switches (21, 35) which alternately couple one terminal of the capacitor to either battery voltage or ground potential in accordance with the voltage regulator output. The above configuration provides a control voltage (44) at the gate of the FET substantially in excess of battery voltage and this insures maximum field current when the FET is on. This is achieved with a minimum capacitance for the capacitor, thus reducing circuit size and cost. Battery current drain of the drive circuit is minimized by disconnecting the one terminal of the capacitor from battery voltage when the FET is off.

Electronically programmable universal brushless DC fan with integral tracking and locked rotor protection

Abstract: A brushless DC fan with a winding supply circuit having an internal voltage regulator can afford current limiting and thermal protection and provide various desired fan speeds without alteration of the basic fan circuit, the windings, or other manufacturing items. A voltage setting circuit element can set fan speed externally and can be used to establish various fan speeds. An internal voltage establishing circuit element sets the maximum speed. The regulator replaces the fan's protective thermistor to shut down the voltage to the windings when locked rotor occurs. Bringing out a lead for the purpose of connecting a speed controlling resistor, thermistor, or active programming means to the internal circuitry enables the fan's end user to alter operation as needed.

A fast time domain digital simulation technique for power converters: Application to a buck converter with feedforward compensation

Abstract: Small-signal analysis was performed earlier to demonstrate the marked improvement of dynamic properties and stability margins of a switching regulator employing a novel feedforward input filter compensation scheme. A large-signal nonlinear recurrent time domain model is presented for the converter to analyze the transient response due to a step input change with and without the presence of the proposed feedforward loop. The results are verified with experimental data.

Phase controlled regulator

Abstract: A phase controlled regulator for selectively connecting a load to an AC source voltage such that substantially constant power is delivered to the load despite fluctuations in the magnitude of the source voltage is comprised of a circuit for detecting the zero crossings of the AC source voltage. A circuit produces a reference signal representative of a periodically increasing value in response to the zero crossings of the AC source voltage. A sensor produces a first signal representative of the instantaneous value of the AC source voltage. A comparator compares the reference signal with the first signal and produces an output signal when a predetermined relationship exists therebetween. A switch is responsive to the output signal for selectively connecting the load to the AC source voltage.

Transmission line voltage detector for static VAR generator

Abstract: In order to maintain low telephone interference (IT factor) during its normal operation and to establish rapid-post-fault voltage support to preserve the integrity of electric power transmission lines in the presence of degraded system impedance and harmonic instability, amplitude detection in a transmission voltage regulator (static VAR generator, SVG) is provided based on real time conventional, or fast, Fourier analysis, data samples being used to establish the fundamental voltage amplitude and collected during a specific, frequency tracking sliding window that precedes the amplitude reading by one line voltage cycle of the transmission line. The number of samples in the window is an integer multiple of the line frequency and, in the case of conventional analysis, the pulse number of the switching power circuit is used in the SVG. The amplitude value is updated after each sampling by shifting (sliding) the one cycle sample data base in a first in - first out manner.

Control system for electric power plant

Abstract: An integrated control system for a power plant having a generator, a turbine, a gate for controlling flow through the turbine, a voltage regulator, a bus and a main circuit breaker. The control system comprises a nonvolatile memory for storing configuration data that includes a plurality of configuration parameters for the power plant. The control system further includes input devices for producing input data concerning current plant conditions including turbine speed, gate position, generator current and voltage, bus current and voltage, and the position of the main circuit breaker. A multi-tasking processor processes the input data in accordance with the configuration data, to produce control signals for controlling the power plant. An editing function is also provided to enable an operator to edit the configuration data, so that the control system can readily be configured for a particular power plant. The editing function may be provided by including a communication port through which the configuration data may be loaded to and from an external device on which the configuration data is edited.

Impact of Voltage Reduction on Energy and Demand: Phase II

Abstract: This paper presents the results of an experimental study involving the impact of voltage reduction on energy use and demand level on selected distribution feeders of differing load composition on the American Electric Power System (AEP). An eighteen month study was conducted on fifteen distribution circuits, during which voltage was reduced by a fixed five percent for the first twelve months, and a variable voltage reduction was implemented for the remainder of the study period. In each case voltage reduction was in effect for a twenty four hour period on alternating weekdays. Analysis of data obtained through field measurements indicates some reduction in energy usage during the reduction period as well as a reduction of demand.

Electronic control circuit

Abstract: An electronic control circuit for use with a varying power supply (21) such as the output from a solar collector or wind generator and a load (22) such as a battery being charged by the power supply, provides two forms of control for maximizing power transfer. Firstly, an inverter (20) with varying duty cycle is connected between supply and load and the circuit controls the duty cycle thereof to maximize power transfer and secondly a stepper motor (25) is connected to the supply to physically alter the power provided by the supply by, in the case of a solar collector for example, altering the angle of the collector relative to the sun. The cirucit compares successive measurements of the output power and generates control signals to alter the angle of the collector and modify the duty cycle. The circuit is adapted to calculate the mean maximum power position. Limit detection is included to prevent latch-up and a voltage regulator is included to override the system.

Stability studies of multimachine power systems with the effects of automatic voltage regulators

Abstract: The stability of power systems including the effects of automatic voltage regulators is studied via Lyapunov's direct method. The multivariable Popov criterion developed by Moore and Anderson is employed in constructing a Lure-type function for a power system consisting of synchronous machines interconnected by a lossless transmission system. The Lyapunov function constructed for the system with only flux decay is regarded as a special case of the result obtained in this paper. The effect of an automatic voltage regulator on power system stability is illustrated by numerical examples, showing some shifts of equipotential curves which are due to changes of voltage regulator gain.

A Single Phase Induction Motor Voltage Controller with Improved Performance

Abstract: Induction motors inherently operate with nearly constant airgap flux and therefore almost constant iron losses. When the load does not require full flux, conventional voltage controllers utilize thyristors in series with the motor to reduce airgap flux by decreasing the applied voltage. Thereby, iron losses decrease and the overall efficiency increases. However, thyristor voltage controllers tend to introduce harmonics into the current waveform which not only reduces motor efficiency but also causes harmonic pollution of the power lines. An improved voltage controller and control strategy for efficiency improvement of single phase induction motors is presented. In particular, thyristor voltage control by dynamic switching of the winding configuration is presented. Laboratory data for a voltage controller, thus enhanced, demonstrates a significant decrease in input motor current distortion and increase in efficiency below one-quarter load.

Control device for power converter

Abstract: The invention relates to the control of a power converter in which the AC side is connected through a reactor to an AC power supply while the DC side is connected to a smoothing capacitor and a load and the power rectification and the power inversion are carried out by the pulse width modulation control. The controls performed include (1) the control, whereby the voltage across the smoothing capacitor coincides with a predetermined value and the current flowing through the reactor and the voltage of the AC power supply have a predetermined phase relationship; (2) the DC component compensation control for eliminating the DC component in an AC circuit within a short time interval and (3) the control of the power conversion operation by utilizing a microprocessor while suppressing the higher harmonics in the AC power supply. The control (1) is performed by using an amplitude signal of the voltage on the AC side of the power converter and a phase difference signal relative to the AC power supply voltage. The control (2) is performed by using the amplitude signal and the phase signal on the AC side of the power converter which cause the current flowing through the reactor to have a predetermined phase relationship with the AC power supply voltage and a detected DC component signal flowing through an AC circuit. The control (3) is performed by using the data of degree of modulation and the phase angle data which are fixed value during a certain period of time and the cross point data stored in the storage means.

Uninterruptible power supply system

Abstract: An uninterruptible power supply system having input terminals connectable to an AC power source and leading to an AC to DC converter for producing a first DC voltage source and a second DC voltage source operationally connected to the first source. The system supplying at the output of the second source a voltage normally primarily provided by the first DC source. A capacitive accumulator device connected in parallel with a voltage sensing and controlling circuit and with the output of the two DC sources. The sensing and controlling circuit controlling the output of at least the second of the DC voltage sources so as to provide at the output terminals of the system a substantially constant output voltage also when the AC power source to which the system is connected in interrupted.

Microcomputer controlled power regulator system and method

Abstract: A load-compensating power distribution regulator system includes a plurality of circuit regulators interfaced to a single microcomputer, the microcomputer sensing for each circuit a regulator voltage and an output current The microcomputer compares a computer line-drop compensated actual circuit voltage with a dynamically determined desired circuit voltage using a variably offset deadband for controlling regulator action depending on whether the output current is changing favorably for bringing the actual circuit voltage toward the desired circuit voltage The number of regulator actions in a time period is also monitored for adjusting the magnitude of the deadband to limit wear-and-tear of the regulator

Ignition system for internal combustion engines

Abstract: An improved ignition system for internal combustion engines including a constant current control circuit for effecting constant current control of an ignition coil primary current, further includes a compensating circuit for controlling a reference voltage, which is to be compared with a detection value of the ignition coil primary current, at a constant value irrespective of a decrease of a power supply voltage, thereby controlling the ignition coil primary current at a given value over a wide range of variations of the power supply voltage including a considerable decrease thereof.

High/low DC voltage motor vehicle electrical system

Abstract: An automotive electrical system with a generator has outputs for loads requiring a high and low voltage, e.g., a heater and a battery. A field-controlled a.c. generator with three-phase output windings has a low voltage main terminal and an auxiliary terminal for high voltage loads. A step-down transformer and a first rectifier connect the windings and the main terminal while a second rectifieer directly connects the windings and the auxiliary terminal. A selector switch having a open and closed positions is connected between the main terminal and the auxiliary terminal. A voltage regulator for controlling current through the generator field is connected to the main terminal. When the selector switch is open the generator provides a dual voltage output i.e., a high voltage level at the auxiliary terminal and a low voltage level at the main terminal; in the closed position of the switch the regulator is connected to the auxiliary terminal and reduces the generator output thereof to said low voltage level while the output of the first rectifier is reduced to an ineffective level, due to the step-down effect of the transformer. The selector switch thus controls the generator output between a dual voltage output (switch open) and a low voltage output (switch closed).

Control apparatus for a vehicle engine electric fuel pump

Abstract: In a dc electric fuel pump control apparatus for controlling the quantity of fuel supplied to a vehicle engine in accordance with an engine operating parameter condition such as an intake air flow condition or engine speed condition, when controlling a voltage applied to a fuel pump operating motor by closing or opening a fixed-resistor short-circuiting switch circuit in accordance with the magnitude of the operating parameter relative to a predetermined value, an increase or decrease of a battery power source voltage from a predetermined value is detected to increase or decrease the predetermined value of the engine operating parameter. Where a variable resistor is used in place of the fixed resistor, its resistance value in a low battery power source voltage condition is controlled lower than that in a high battery power source voltage condition.

Supplemental automotive vehicular heater system and method of providing same

Abstract: A supplementary heating system particularly suitable for an automotive vehicle comprises a step down transformer coupled to the stator windings of the vehicle's alternator and a positive temperature coefficient (PTC) of resistivity heater electrically connected intermediate the stator windings and the transformer in parallel with the transformer. Due to the presence of the transformer the voltage regulator causes the alternator to operate at a higher than customary voltage to provide the conventional 14.4 volts for the vehicle's normal electrical loads with the high voltage used to energize the heater. The heater can be in the form of a so-called "honeycomb" having a plurality of parallely extending passages or cells disposed in the air stream going from the main heater into the passenger compartment and can be either a multiphase, single phase or direct current type. In one embodiment the transformer is switched into and out of electrical coupling with the alternator dependent on the energization of the heater, while in another embodiment the transformer is always electrically coupled to the alternator with the heater switched into and out of the circuit as desired.

High voltage power supply system including inverter controller

Abstract: A high voltage power supply system includes a DC-to-DC converter for producing a DC low voltage, a DC-to-AC inverter connected to a step-up transformer for producing an AC high voltage by transforming an AC low voltage obtained from the DC low voltage, and an inverter controller for controlling an operation time period of the DC-to-AC inverter longer than that of the DC-to-DC converter. Since a residual charge stored in a capacitor of the DC-to-DC converter is rapidly discharged by lengthening the operation time period of the DC-to-AC inverter, an unwanted AC high voltage is induced at a secondary winding of the step-up transformer.

Switching circuit utilizing a field effect transistor

Abstract: A switching circuit that utilizes an N-channel field effect transistor. The circuit can be used in a generator voltage regulator wherein the drain and source of the transistor are connected in series with the field winding of the generator. The circuit includes a capacitor that is repetitively charged and discharged. At the end of the charge period a gate bias voltage is developed that is applied to the gate of the transistor. The magnitude of the gate bias voltage that is developed is the sum of the capacitor voltage and the voltage of a voltage source. The capacitor is allowed to discharge until the gate bias voltage decreases to a value that is high enough to maintain the transistor conductive whereupon the discharge period is terminated and the capacitor is recharged. The system responds to the magnitude of the output voltage of the generator relative to a reference voltage and will cause the transistor to be biased conductive or nonconductive for total time periods that are equal to the sum of a plurality of consecutively occurring timing periods.

A bi-directional high power cell using large signal feedback control with maximum current conduction control (MC 3 ) for space applications

Abstract: Bi-directional current flow power cell principle is analysed and large signal state feedback control is presented by using the PWM buck - SMART power cell.

Voltage-insensitive and temperature-compensated delay circuit for a monolithic integrated circuit

Abstract: A delay circuit which is insensitive to variations in power supply voltage, which is temperature-compensated, and which is suitable for fabrication in a monolithic integrated circuit includes circuitry for charging a capacitive element through a resistive element from GND toward the power supply voltage. The voltage across the capacitive element is compared to a reference voltage by a voltage comparator, and the voltage comparator generates an output signal when the voltage on the capacitor becomes greater than the reference voltage. The reference voltage for the comparator is generated by a resistor divider connected between GND and the power supply voltage. Inasmuch as the reference voltage varies with changes in the power supply voltage in such a manner as to be maintained at a substantially fixed percentage of the power supply voltage, the time delay provided by the delay circuit is essentially independent of variations in power supply voltage. By utilizing resistors in the resistor divider that have differing temperature coefficients of resistance, the reference voltage for the comparator can be increased and decreased in a predetermined manner in response to increases and decreases in ambient temperature, allowing the time delay of the delay circuit to be adjusted in a predetermined manner as a function of temperature.

Transfer apparatus, regulating apparatus and methods

Abstract: Transfer apparatus for use with an AC generator having a field winding, the DC energization of which controls the output of the generator. Associated with the generator are first and second voltage regulators each including means for sensing the output of the generator and means for varying the DC energization of the generator field winding to regulate the output of the generator to a respective reference level for each voltage regulator. The transfer apparatus includes a circuit for generating a first signal as a function of the generator output as sensed by the first voltage regulator sensing means and a second signal as a function of the generator output as sensed by the second voltage regulator sensing means. Another circuit independently produces an additional signal to which the first and second signals ordinarily have a predetermined relationship. A further circuit selects the first or second voltage regulator to energize the generator field winding. The selection depends on whether or not there is a departure of the first signal from the predetermined relationship to the additional signal when the second signal maintains its predetermined relationship thereto. Other transfer apparatus and regulating apparatus and methods are also disclosed.

Voltage regulator for alternator of vehicle

Abstract: A voltage regulator maintains an output voltage of an alternator of a vehicle to a voltage in the vicinity of a preset voltage. The voltage regulator has a microcomputer for setting the OFF duty ratio, a switching circuit for switching on or off an electric current flowing through a rotor coil of the alternator and a load sensor for detecting the operation of the intermittent load. The microcomputer sets the OFF duty ratio to a value directly proportional to the difference between the output voltage and the preset voltage before the operation of the intermittent load is started. And the microcomputer gradually decreases the OFF duty ratio set by said duty ratio setting means at the initial operation time of the intermittent load, and memorizes the OFF duty ratio when the output voltage reaches its upper limit value exceeding the preset voltage. The microcomputer changes the OFF duty ratio to an average value of the OFF duty ratio set by the duty ratio setting means and the OFF duty ratio memorized by the memory means when the reoperation of the intermittent load is detected within a prescribed time after the initial operation of the intermittent load.

Dual voltage motor vehicle electrical system

Abstract: A dual voltage motor vehicle electrical system wherein batteries are series connected across the direct voltage output terminals of a generator. The system has a DC to DC converter that operates in a first mode as an equalizer to maintain the batteries in a substantially equal state of charge. When an electric starting motor is energized to crank the engine of the vehicle the converter is switched to a second mode of operation wherein it provides a substantially constant output voltage that is applied to certain electrical loads on the vehicle that require a stable voltage. The converter responds to a first reference voltage that is provided by a voltage divider connected across the batteries when operating in the first mode and responds to a second reference voltage provided by a constant voltage device when operating in the second mode. The system switches between the reference voltages, depending upon the mode of operation that is being used.

Bias circuit for an avalanche photodiode

Abstract: A bias circuit accurately compensates temperature coefficient of an optical multiplication in an avalanche photodiode with low power consumption. Temperature coefficient voltage for compensating temperature coefficient of the multiplication of the photodiode is delivered from an emitter follower added a constant voltage to an input of an operational amplifier. The output of the operational amplifier is added, via a voltage regulating diode, to a base of a transistor of which emitter and collector are respectively connected to a terminal of the photodiode and a negative power source. Emitter voltage of the transistor is dividedly connected to another input terminal of the operational amplifier, wherein this connection is negative feedback. The temperature coefficient voltage generated at the emitter follower is amplified inversely proportional to the divided ratio of the emitter voltage of the transistor in order to compensate the temperature coefficient of the multiplication of the photodiode. A voltage across the photodiode can be adjusted by adjusting the constant voltage added to the emitter follower. Voltage drifts caused by temperature variations in the negative feedback loop including the operational amplifier, the voltage regurating diode, the transistor and the voltage divider are entirely eliminated with the negative feedback operation.

Power down sense circuit

Abstract: A low voltage sense circuit for a microprocessor controlled television receiver includes a 5 volt regulator having a large electrolytic capacitor coupled across its output, which is the power input terminal of a microprocessor. The microprocessor includes a sleep terminal for initiating operation in a minimum power consumption mode. The 12 volt input to the 5 volt regulator is coupled to the bias circuit of a PNP transistor that includes a Zener diode and which is in saturation as long as the input voltage to the 5 volt regulator is greater than the breakdown voltage of the Zener diode. The collector output of the transistor is connected to the sleep terminal of the microprocessor. When the transistor is driven out of saturation, an appropriate voltage change is developed at the sleep terminal for causing the microprocessor to switch to its low power sleep mode.