Showing papers on "Voltage regulation published in 1984"

CMOS backup power switching circuit

Abstract: A load circuit is provided with a backup power supply to power the essential functions of the load in the event that its primary power supply fails or is otherwise degraded. The positive terminals of both the primary power supply and the backup power supply, having a common negative reference, are input to a differential voltage comparator circuit. The output of the differential voltage comparator circuit controls a switching transistor located in a line between the primary power supply and the load, and when inverted by an inverter circuit, controls a second switching transistor located in a line between the backup power supply and the load. In operation, only the more positive of the primary power or the backup power supply voltages is provided to the load. The output of the inverter circuit is also available to indicate which of the two sources the power is applied to the load, and may be further used to disable non-essential portions of the load circuitry.

Full load to no-load control for a voltage fed resonant inverter

Abstract: 57 A control for a voltage fed series resonant inverter includes controllable switch means (83, 85) which supplies square wave voltage signals to a resonant series circuit (95; 97). The output of the inverter is coupled to a rectifier (99) to provide dc power to a load. The control comprises summer means (58) for comparing a commanded dc voltage (Eo) to an actual dc output voltage and providing an error signal. An oscillator (64) responsive to the error signal generates a frequency signal that is coupled to the controllable switch means (83, 85) to vary the frequency of the square wave voltage supplied to the resonant circuit. The duty cycle of the frequency signal is adjusted so that the frequency signal is provided in bursts during low load conditions thereby minimizing circulating currents while maintaining the output voltage with dosed loop frequency control.

Electric power distribution and load transfer system

Abstract: A power distribution system includes a plurality of power sources and load transfer units including transistors and diodes connected in series and leading to a common power output, each of the transistors being controller switchable subject to voltage levels of the respective input and output sides of said transistors, and the voltage and current level of said common power output. The system is part of an interconnection scheme in which all but one of the power sources is connected to a single load transfer unit, enabling the survival of at least a single power source with the failure of one of the load transfer units.

Uninterruptible power system.

Abstract: In power systems for providing an uninterruptible power supply to a load (24), a problem may arise in the switching of power from a main line (12) to a standby generator (20). A power system that overcomes the above problem further includes a first motor (14), a first generator (16), a flywheel (62) and a transfer controller (92). When the main line (12) fails to provide the necessary power, the energy developed by flywheel (62) is used to supply power to a load (24) until a standby generator (20) is available to supply power. The power system can be used with a three phase 240 voltage load (24).

Modeling and Analysis of Under-Load Tap-Changing Transformer Control Systems

Abstract: This paper considers the problem of modeling and analysis of under-load tap-changing (ULTC) transformer control systems. A nonlinear system model is derived, suitable for analysis of voltage and reactive power flow control applications of ULTC transformers in the consideration of mid-term and long-term dynamics and steady-state behavior of power systems. The model is verified with the example of a distribution ULTC transformer, used for the voltage control. As an illustration of the feasibility of the model in various voltage and reactive flow control applications, some digital simulation results of such a distribution voltage control are also presented.

Modular power supply system

Abstract: A power distribution system intended for use in a highly modular desk top computer system conserves user space, prevents excessive heat and reduces RFI. The invention provides a programmable modular DC power supply including a power module (10) that produces a first fixed regulated DC voltage which is coupled from the power module (10) to a power bus (19). Thereafter the first voltage is distributed to a plurality of DC-to-DC convertors (11, 14), each of which is operable to change the first DC voltage to a second regulated DC voltage selected from a plurality of programmed voltage values.

System for parallel power supplies

Abstract: A system and method of connecting power supplies in parallel that provides desired voltage regulation at the load and current sharing between the power supplies. The power supplies are connected in parallel at the load. Each power supply also has a sense line connected at the load. Each power supply includes means for measuring the current delivered to the load. Each supply also includes an electronically controlled variable resistive element in its respective sense line. The amount of current being supplied by each power supply to the load is measured. A controller determines if an unacceptable imbalanced current condition exists, i.e., it determines which power supply is supplying too much or too little current and the controller selectively changes the value of the appropriate variable resistive element in the sense line of that power supply in order to change the current being delivered to the load in a direction that corrects for the imbalanced condition. All such corrections are controlled so that a desired voltage regulation is maintained at the load.

Power-saving voltage supply

Abstract: In a semiconductor device according to the invention, first and second voltage dropping circuits, for generating voltages respectively having smaller values than that of an external power supply voltage, are provided. The first voltage dropping circuit, which consumes relatively less power, is always in the operative mode, and the second voltage dropping circuit, which consumes more power than that of the first voltage dropping circuit, is operated during an interval other than a standby interval. The voltages generated by the first and second voltage dropping circuits are supplied to an internal power supply line in parallel with each other.

Simulation study of DC transit systems with inverting substations

Abstract: The increasing use of chopper-controlled regeneratively braked stock in rapid transit and suburban railways has brought into focus the problems of limited energy receptivity in the DC supply network. While the use of on-board rheostatic braking or mechanical braking are established methods of dealing with non-receptivity, an alternative arrangement using inverting equipment at the DC substation has been introduced at some locations in Japan, Germany and Brazil. This paper describes a simulation-based study of a rapid-transit system with substation inverters, which was undertaken to establish operating limits and optimum design criteria which could be generally applicable. The paper deals with the choice of installed inverter capacity, inverter location, current commutation limits and inverter control. In addition the energy-saving consequences of using inverter equipment are discussed in detail. The implications of fitting inverters, with respect to the bulk AC supply system, in terms of voltage distortion, voltage regulation and reactive power demand, are considered for a range of typical values of short-circuit level.

A.c. supply converter

Abstract: A direct a.c. supply converter for converting an N (≧2) phase input voltage system into an a.c. output voltage system of different frequency, amplitude, and/or phase using width-modulated contributions from the phases of the input voltage system to produce the output voltage system suffers from the disadvantage that the maximum output voltage amplitude can be limited to the minimum instantaneous voltage of the input voltage system because of the arbitrary timing relationship between the two voltage systems. This limitation is relieved by the addition of a component at the N th harmonic of the input system frequency to the width-modulation so that the effective minimum instantaneous voltage of the input system is increased. An increase in the maximum output voltage amplitude can also be obtained by adding to the width-modulation a component at the P th harmonic of the output system frequency; this can be used along or in conjunction with the component at the N th harmonic of the input system frequency.

Voltage detection circuit for detecting input voltage larger in absolute value than power supply voltage

Abstract: A voltage detection circuit for detecting an input voltage larger in absolute value than a power supply voltage is disclosed. This circuit comprises a first transistor connected between a terminal supplied with the input voltage and a circuit node, and a second and a third complementary transistors connected in series between the circuit node and a reference potential terminal. The first transistor is used as a voltage-dropping means, and the gates of the second and third transistors are commonly supplied with the power supply voltage. When the potential difference between the circuit node and the gate of the second transistor exceeds the threshold value of the same transistor, the second transistor is turned ON and the potential at the connection point of the second and third transistors begins to change. At this time, the input voltage is higher in absolute value than the power supply voltage because the first transistor operates as the voltage-dropping means.

Dual slope, feedback controlled, EEPROM programming

Abstract: A floating-gate, electrically-erasable, programmable read-only memory cell is programmed or erased by a high voltage across a thin oxide area between the floating gate and the substrate. A tunnelling phenomena is produced by the high voltage. In order to protect the thin oxide from excessive stress, yet minimize programming time, the maximum electric field is controlled by a dual-slope waveform for the programming voltage Vpp. The values of slope and breakpoints for this dual-slope Vpp voltage are selected by a feedback arrangement which is responsive to process variations in threshold voltage, supply voltage, etc.

Optimal Voltage Dependent Continuous-Time Control of Reactive Power on Primary Feeders

Abstract: The availability of substation-based computers and the decreasing relative cost of installation, operation and control of switched capacitors encourage the use of more sophisticated and effective capacitive compensation schemes for loss minimization on radial distribution feeders. This paper sets forth a new voltage dependent model for the optimal control and design problems involving continuously controllable shunt capacitors on primary feeders. The new model obviates the need for a load-flow solution while allowing inclusion of the effects of voltage variation on the design and control phases of an optimal capacitive compensation scheme. The benefits and limitations of the model are reflected via numerical examples.

Load management control system and method

Abstract: A load management control system and method which communicates load shedding information from a central station controller via existing telephone lines to a substation controller The substation controller in turn controls the tap position selection of a load tap changing transformer to send encoded step voltage signals down a power distribution line to a load control receiver The load control receiver decodes the encoded signal message and appropriately controls uniquely associated loads The substation controller interrupts automatic operation of the voltage maintenance circuitry of the load tap changing transformer during transmission of a message Control is returned to the automatic circuitry of the load tap changing transformer after the message is completed so as to make existence of the load management control system of the present invention transparent to existing equipment in the field The method of the present invention maximizes utilization of existing lines of communication and existing power distribution field equipment while minimizing the effect on that same equipment

Dual voltage power supply system for vehicles

Abstract: A dual voltage power supply for a vehicle is disclosed with a DC generator, a single storage battery, a low voltage load circuit including the storage battery and a high voltage load circuit including load devices designed to be powered by voltages higher than the battery voltage. A high voltage regulator is responsive to the generator output voltage and controls the energization of the field winding of the generator for causing the generator to produce an output voltage meeting the requirements of the high voltage load circuit. A low voltage regulator receives the output voltage of the generator and produces a substantially constant regulated voltage for charging the battery and supplying the low voltage load circuit.

Electronically switchable power source

Abstract: A DC power source is capable of automatically adapting to either a 120 or 240 VAC input and of providing a single regulated output range for either of the AC voltage levels provided thereto. The power source detects the AC input voltage and automatically doubles the lower voltage while allowing the higher rectified voltage to pass through. The power source includes an electronic switching arrangement responsive to the input voltage level for automatically doubling the lower AC input voltage when detected as well as timing circuitry to allow for transitory fluctuations in the input voltage level while maintaining a level DC output voltage.

CMOS bias voltage generating circuit

Abstract: A bias generating circuit for reducing an external DC power supply voltage to a predetermined, lower, stable DC voltage used as a power source for internal logic circuits in a semiconductor IC chip includes an oscillator for converting the external DC voltage into a pulse signal, a smoothing circuit for converting a pulse signal into the lower DC voltage, and a control circuit interposed between the oscillator and the smoothing circuit for varying the pulse duration of the pulse signal from the oscillator to a changed pulse signal, and for regulating the lower DC voltage to a predetermined amplitude in response to the voltage variation in the lower DC voltage. The control circuit comprises a CMOS inverter, a CMOS buffer circuit for varying the pulse duration of the output signal of the CMOS inverter, and a voltage compensating circuit for controlling the transconductance of the CMOS inverter in response to the variation of the lower DC voltage.

Direct-current power supply with alarm indicator

Abstract: A direct-current power supply for supplying electric current to a load and operable with a plurality of types of batteries includes a housing unit for loading therein batteries employed, a monitor device for monitoring a voltage output from batteries in use, an indicator for indicating a warning, a comparing device which compares the monitored voltage with a reference voltage to energize the indicator when the monitored voltage becomes lower than the reference voltage, a voltage generating unit for generating a plurality of voltages as the reference voltages associated with the types of batteries available, and a selecting unit for selectively supplying one of the plurality of voltages generated to the comparing device. Each of the plurality of voltages is set to a value higher than a limit voltage which is sufficiently low for allowing an normal operation of the load.

Constant current r.f. generator

Abstract: The present invention achieves constant voltage at radio frequencies to drive a constant voltage to constant current converter, by employing a tightly coupled d.c. feedback loop to control the voltage via a transformer to the drain of a FET operated as a Class C amplifier in the saturated mode whereby among other advantages, the amplifier can withstand, without damage, very high VSWRs. Control is affected by a high gain differential amplifier which compares a d.c. voltage derived from the r.f. output of the system against a highly stable d.c. voltage reference. A controller, responding to the output of the differential amplifier causes a first level of voltage to be applied to the drain of the FET when the system is not loaded and causes a second voltage varying between said first level and a higher level when the system is loaded. In the lower voltage condition the controller is effectively removed from the system so that it does not have to drop a high voltage to a low voltage; the low voltage being supplied effectively from a separate source.

Frequency controlled resonant regulator

Abstract: The primary winding of a high leakage inductance power tranformer is coupled to a source of unregulated voltage and to a square wave voltage generator that includes first and second alternately conducting output switching transistors. A voltage controlled oscillator establishes the operating frequency of the voltage generator. A resonating capacitor is coupled to a transformer secondary winding that is loosely coupled with the primary winding. The capacitor forms a series tuned circuit with the leakage inductance between the primary and secondary windings of the transformer. The operating point of the tuned circuit voltage verses frequency characteristic curve determines the amplitude of the generally sinusoidal output voltage across the secondary winding, in accordance with the operating frequency of the square wave voltage generator. A feedback circuit senses the amplitude of the output voltage and varies the frequency of the voltage controlled oscillator to regulate the output voltage.

Liquid crystal element driving apparatus

Abstract: An apparatus for driving a liquid crystal element by an increased voltage and at a lowered frequency in conformity with temperature fall in the liquid crystal element so as to achieve complete driving of the element even in a low temperature range. In order to increase the driving voltage, the apparatus comprises a booster circuit for increasing a battery voltage, and a voltage divider circuit including an element-temperature sensor as a component thereof and serving to produce a control voltage by dividing the output voltage of the booster circuit. In such configuration, the booster circuit performs its operation in such a manner as to maintain constant the control voltage obtained from the voltage divider circuit.

Off-line switching mode power supply

Abstract: An off-power line switching mode power supply which employs current and voltage feedback and sensing converts primary rectified, unregulated high voltage to a number of regulated d.c. secondary voltages and a low frequency, high voltage output suitable for enabling ringing of standard telephones. Two high voltage field effect transistors connected in the half-bridge configuration power multiple output circuits via a capacitively coupled transformer. A pulse width modulator controls the high frequency switching times of the field effect transistors via a transformer-coupled drive circuit.

Electronic control circuit, electronically commutated motor system and method for controlling same, laundry apparatus, and methods for operating apparatus for switching high voltage DC and for controlling electrical load powering apparatus

Abstract: Electrical load powering apparatus has a load connection, a high voltage supply connection and a common, and includes electronic means for switching the high voltage supply connection to the load connection. The electronic switching means has an input and is responsive to a control voltage difference between the input and the load connection. The load connection is subject to high voltage excursions relative to the common due to the switching. An electronic control circuit for use in the electrical load powering apparatus includes a circuit having an active device for providing at least one pulse output relative to common and having at least one inherent capacitance. A circuit connected to the load connection inverts the pulse output of the circuit having the active device to produce the control voltage difference between the electronic switching means input and the load connection. An additional circuit charges the inherent capacitance of the circuit having the active device when one of the high voltage excursions occurs. An electronically commutated motor system, a regulated power supply and laundry apparatus utilizing the electronic control circuit are set forth. Methods for controlling the motor system, for operating apparatus for switching high voltage DC and for controlling electrical load powering apparatus generally are also described.

Power switch for dual power supply circuit

Abstract: A power switching circuit 12 for automatically switching between line-driven and battery power supplies 28 and 30 is disclosed. The power switching circuit selectively connects first and second input voltage terminals Vdd and Vbb to an output voltage terminal Vzz. When the line-driven power supply is on, a first transistor Q1 switches on to connect the first input voltage terminal to the output voltage terminal, and a second transistor Q2 switches off to isolate the battery. When the line-driven power supply is off, the first transistor switches off, and the second switches on to connect the battery powered second input voltage terminal to the output voltage terminal.

High voltage pulsed power supply with time limiting nonlinear feedback

Abstract: An apparatus for supplying high voltage pulsed direct current to an X-ray tube includes a transformer, a high frequency inverter circuit and a nonlinear feedback loop. The invention uses the high frequency inverter connected in series with a DC power supply source and the primary winding of the transformer in order to generate high voltage, high frequency AC in the secondary winding. A rectifier connected to the secondary winding supplies high voltage pulsed DC to the X-ray tube. A detector, such as a voltage divider, detects the voltage supplied to the X-ray tube and supplies a representation of it to a nonlinear feedback circuit connected between the detector and the high frequency inverter. The inverter circuit includes at least one switch generated by electrical pulses. The nonlinear feedback circuit controls the duty cycle of the inverter during only a portion of the output voltage range of the high voltage pulsed power supply, preferably only after the output voltage reaches 90% of the rated high voltage to be supplied to the X-ray tube.

Protection system for immunizing a controlled d-c power supply against a-c line voltage interruptions

Abstract: When a d-c bus voltage is produced by rectifying applied a-c power line voltage in a rectifier bridge (such as a phase-controlled SCR rectifier bridge), controlled by a feedback loop which compares a feedback signal representing the d-c bus voltage with a command signal representing a desired set point level and from the comparison automatically maintains the bus voltage at the set point level, unwanted a-c line voltage interruptions may have a deleterious effect on the rectifier bridge itself and on a load driven by the bus voltage. This occurs because during a power interruption (when the bus voltage drops) the command signal causes the feedback loop to impose a control on the rectifier bridge which attempts to increase the d-c bus voltage back to the magnitude represented by the command signal. When power is subsequently restored, the d-c bus voltage will suddenly increase very sharply and may destroy electrical and/or mechanical components in the system. Immunization against the effects of the power interruptions is obtained by substituting the feedback signal for the command signal, during the occurrence of a power interruption, which will shut the rectifier bridge down and will force it to produce only a minimum amplitude d-c bus voltage when power is later restored. After power resumes, the rectifier bridge will be controlled by an acceleration regulating circuit so that the bus voltage gradually increases, at an adjustable rate, back up to the desired level set by the command signal.

Circuit for voltage multiplication

Abstract: A circuit for voltage multiplication has a capacitor which is connectible via first switching transistors to a supply voltage source and via further first switching transistors in series with the supply voltage source and with a storage capacitor which is connected in parallel to the circuit output. Clock voltages for driving the first switching transistors are switchable in amplitude from a value corresponding to the supply voltage to the value corresponding to the output voltage. In order to achieve high efficiency of the circuit, a clock voltage generator is controllable for amplitude switch over via a supply line which is connectible via a second switching transistor to the supply voltage source and is connectible via a third switching transistor to the circuit output, whereby these switching transistors are driven via the outputs of the comparator which compares the supply voltage to the output voltage. The circuit may advantageously be employed in hearing aid circuits.

Control system for engine-driven generator

Abstract: There is disclosed herein a generator control system for use in a power supply system for vehicles in which a battery and an engine-driven generator are connected in parallel with a load. The total load current fed to the load is detected and the generated voltage level is changed by performing field regulation for the generator in accordance with the detected value. Switching of the generated voltage level of the generator is controlled according to the state of the load applied so as to improve power generation efficiency. Certain parameters, such as battery state, engine speed, auto choke and load state, can be provided as an input or inputs to a voltage regulator for the generator.

Effects of Voltage Control in Utility Interactive Dispersed Storage and Generation Systems

Abstract: When a small generator is connected to the distribution system, the voltage at the point of interconnection is determined largely by the system and not the generator. This paper examines the effect on the generator, on the load voltage and on the distribution system of a number of voltage control strategies. Synchronous generators with three kinds of exciter control are considered, as well as induction generators and constant extinction angle inverters, with and without capacitor compensation. Operation with a constant slightly lagging power factor is shown to have some advantages.