Showing papers on "Voltage drop published in 1997"

Static Synchronous Series Compensator: A Solid-State Approach to the Series Compensation of Transmission Lines

Abstract: This paper describes an active approach to series line compensation, in which a synchronous voltage source, implemented by a gate turn-off thyristor (GTO) based voltage-sourced inverter, is used to provide controllable series compensation. This compensator, called static synchronous series compensator (SSSC), can provide controllable compensating voltage over an identical capacitive and inductive range, independently of the magnitude of the line current. It is immune to classical network resonances. In addition to series reactive compensation, with an external DC power supply it can also compensate the voltage drop across the resistive component of the line impedance. The compensation of the real part of the impedance can maintain high X/R ratio even if the line has a very high degree of series compensation. Concurrent and coordinated modulation of reactive and real compensation can greatly increase power oscillation damping. The paper discusses the basic operating and performance characteristics of the SSSC, and compares them to those characterizing the more conventional compensators based on thyristor-switched or controlled series capacitors. It also presents some of the results of TNA simulations carried out with an SSSC hardware model.

Motor current sense circuit using H bridge circuits

Abstract: A circuit is used for sensing motor current. This circuit maximizes the power delivered to the motor whose current is being sensed. Further, this circuit results in maximum voltage drop across the motor. This circuit implements a mirrored H-bridge to mirror a current flowing through a conventional H -bridge having a sensing resistor in series with a VCM motor. The voltage drop across the sensing resistor serves as an indication of the current flowing

Characterization of voltage sags in industrial distribution systems

Abstract: This paper describes the various characteristics of voltage sags experienced by customers within industrial distribution systems Special emphasis is paid to the influence of the induction motor load on the characterization of voltage sags During a fault, an induction motor operates as a generator for a short period of time and causes an increase in sag magnitude Its reacceleration after the fault clearance results in an extended post-fault voltage sag The influence of the induction motor on the imbalanced sags caused by single line-to-ground faults (SLGFs) and line-to-line faults (LLFs) has been analyzed in detail For an imbalanced fault, the induction motor current contains only positive- and negative-sequence components Induction motors create a low impedance path for the negative-sequence voltage due to an imbalanced fault This causes a small sustained nonzero voltage with large phase-angle jump in the faulted phase and a voltage drop in the nonfaulted phases with a small phase-angle jump The symmetrical components of the induction motor during the imbalanced sags have been studied The results show that induction motor behavior is determined by positive- and negative-sequence voltages during the imbalanced sag

High sensitivity battery resistance monitor and method therefor

Abstract: The method and the apparatus for detecting a deteriorating condition in a bank of standby batteries includes injecting an audio frequency current into one of the battery buses or cables, detecting an audio frequency current signal, matched to the injected audio frequency current signal, that is carried by the battery bus and detecting a voltage drop, at the audio frequency, across the bank of standby batteries. In one embodiment, current transformers are utilized in connection with an oscillator (to inject the AF current signal) and detection circuits (comparators and operational amplifiers) are utilized to generate a representative current signal and a representative voltage signal. The device detects when the standby batteries are operating in a normal, stable condition, that is, when the bank is neither being recharged nor is discharging DC power to the load. During normal, stable operating conditions, a differential relationship is established between the representative voltage and representative current signals. In one embodiment, a microprocessor-based system monitors the float voltage of the battery in order to ascertain when the battery system is in a normal, stable operating condition. The microprocessor also initially establishes the differential between the representative voltage and the representative current signals. The method includes determining when the differential relationship between the voltage and current signals exceeds a predetermined value and issues an alarm signal at that time. The alarm signal may be deferred until the differential relationship exceeds the predetermined value for a predetermined period of time. In one embodiment, this analysis is conducted in the microprocessor-based system.

Improved modulation techniques for PWM-VSI drives

Abstract: PWM-VSI based AC motor drives have two main problems. The inverter is nonlinear which causes instability problems in some specific working points of the AC machine and it emits acoustic noise due to the switching frequency. Nonlinearities like dead-time in the inverter, load dependent DC-link voltage ripple and the voltage drop across the switches are modeled and compensated by improved modulation techniques in order to obtain an almost ideal inverter. Different feedback and feedforward techniques are proposed. The acoustic noise is reduced by using a random modulation strategy. Measurements show a significant improvement by using feedforward and feedback techniques for linearizing the inverter. An improvement in reduction of the acoustic noise emission is also achieved by using random modulation. It is concluded that a combination of a random modulation strategy and feedforward/feedback techniques gives an almost ideal AC motor drive system.

Full-wave rectifier and method of operation for a recognition system

Abstract: A full-wave rectifier circuit (70) includes a first transistor (N1) and a second transistor (N2) in combination to form a first transistor pair (N1 and N2) for minimizing the voltage drop between ground (88) and the transponder substrates. A third transistor (P1) and a fourth transistor (P2) operate in combination to form a second transistor pair (P1 and P2) for minimizing the voltage drop between the alternating current peak voltage (118 and 120) and the output voltage (VDD) of the full-wave rectifier (70). The first transistor pair (N1 and N2) and second transistor pair (P1 and P2) are controlled by alternating current voltage input signals (118 and 120). A series regulator circuit (70) decouples the first transistor pair (N1 and N2) and the second transistor pair (P1 and P2) from capacitive loads (C1 and C2) of the full-duplex transponder circuitry (14).

Design strategies and decoupling techniques for reducing the effects of electrical interference in mixed-mode IC's

Abstract: A key issue in the successful integration of analog circuits is a stable analog power supply. Traditional on-chip decoupling methods exhibit transients in the supply or voltage drops and power losses. This paper introduces the RLC decoupling method that features an enhanced transient response while being especially suited for low-power, low voltage applications. Both a theoretical and a practical approach are presented together with measurement results. As the benefits of a stable local power supply can be lost by the inadequate connection of two subcircuits with relative variations on the local grounds, a differential approach of signal transfer is proposed. Furthermore, the effect of a good local decoupling can be deteriorated by substrate noise, so some attention is given to this problem too.

Current sharing power supplies with redundant operation

Abstract: A plurality of power supplies are connected in parallel, each power supply isolated from the others using a non-linear isolation element such as a barrier diode. Feedback is furnished around the non-linear isolation element such that the voltage drop of the isolation element is reduced to be within the regulation range desired. The non-linear characteristic of the isolation element combined with feedback produces an output impedance which is low for high currents, and exponentially higher for low output currents for current sharing versus output offset voltage improvement.

Circuit and method for driving an organic light emitting diode (O-LED) display

Abstract: Disclosed is a technique for driving a column of pixels implemented using O-LEDs. The technique includes separate, digitally adjustable current sources on each column conductor of the array. For each column, the digitally-programmed current flow terminates with a reference O-LED and a series NMOS transistor forming the input leg of a novel, distributed current mirror. The current is "mirrored" to the output leg of the distributed current mirror which can service any one of a plurality of active O-LEDs in the column based on a row select signal. In this way, a transistor on the output leg of the current mirror couples its respective O-LED to a source of operational power. The mirrored charge on the gate of the output leg transistor causes it to apply the same current to the active O-LED as was applied to the reference O-LED through the input leg transistor. Additionally, the voltage drop across the NMOS transistor and the reference O-LED is used to charge a capacitor associated with the selected O-LED. The charging of the capacitor, as a result of the digitally-programmed current supplied through the NMOS transistor to the reference O-LED, allows for continuous driving of the active O-LED during a cycle through. Thus, a reference O-LED in conjunction with an NMOS transistor, services all of a plurality of sequentially-loaded rows within each column.

Ring oscillator using even number of differential stages with current mirrors

Abstract: A ring oscillator having an even number of differential amplifier stages is disclosed wherein each stage includes a differential amplifier using two N-channel MOSFETs whose gates serve as the inputs and whose drains serve as the outputs of the stage. The sources of the two MOSFETs are connected together and to a current sink consisting of a cascoded structure of N-channel MOSFETs. The drains of each of the two N-channel MOSFETs serving as the differential amplifier are each connected to a respective current source provided by a P-channel MOSFET. All of the current sinks in the stages are connected as secondary legs of a first current mirror which establishes a current of I in the sinks. All of the current sources are connected as secondary legs of a second current mirror which attempts to establish a current of (1+∝)I/2 in each of the sources, where ∝ is a number greater than zero. Since an average current of only I/2 can be drawn from each of the current sources, the voltage drop across each current source is reduced, thereby limiting the range of the average common mode output voltage for each stage of the oscillator.

Liquid level sensor utilizing AC and resistance

Abstract: A liquid level detecting system for detecting a conducting liquid level in a non conductive container which utilizes a grounding rod mounted in a lower portion of the container and a conductive sensing rod mounted at a position above the grounding rod. An oscillator is provided having a frequency in the range of about 600 hertz to about 100 kilohertz. The output of the oscillator is applied to the sensing rod through a high impedance circuit and a high pass filter. In another embodiment, the high pass filter may have the higher end frequencies attenuated to produce a band pass filter which selectively passes the frequency of the oscillator. The voltage drop across the circuit which includes the conductive sensing rod to ground is detected by a voltage peak detector and a threshold detector to produce an output which detects the drops in voltage when the conductive fluid level in the tank rises so that both the sensing rod and the grounding rod are covered, completing the circuit. In another embodiment, multiple sensing rods may be positioned at various heights in the tank to detect various fluid levels. The use of the high pass or band pass filters in series with the sensing rod and ground will eliminate any DC current in the rods thereby reducing electrolysis. The filters also eliminate or significantly reduce interference or artifacts due to DC and 60 hertz.

Vehicle electrical power back-up circuit and method

Abstract: A vehicle electrical back-up circuit and method. Vehicle electrical devices normally receive the power required for their operation from a vehicle electrical system at a first voltage. An auxiliary storage battery is provided at a second, lower voltage. Preferably, charge is maintained in the battery by a charging circuit powered by the vehicle electrical system. A voltage booster circuit boosts the second voltage of the auxiliary storage battery back to the first voltage, providing auxiliary electrical power available for operating the electrical devices.

Soft-start switch with voltage regulation and current limiting

Abstract: A MOSFET, an op-amp, a comparator circuit, and voltage dividers with capacitors are employed in combination to effectuate a soft-start switch with current limiting The transconductance of the MOSFET is employed so that no sense resistor is required The MOSFET and op-amp are configured as a closed-loop feedback circuit in which the output of the op-amp is coupled to the gate of the MOSFET and the inverting input of the op-amp is coupled to the output of the soft-start switch via a voltage divider A first RC circuit provides a voltage to the non-inverting input of the op-amp which can be triggered to gradually rise from a value close to zero to some reference voltage so as to soft-start a load Current limiting means are effectuated by a comparator circuit and voltage dividers with capacitors The current limiting means brings the MOSFET to an OFF state and the non-inverting input of the op-amp close to zero volts if the op-amp charges a second RC circuit so that the voltage drop across its capacitor exceeds a pre-determined limit-reference, and also, once the current limiting means brings the MOSFET to the OFF state, the current limiting means allows the soft-start switch to begin a soft-start power-up after a pre-determined time dependent upon the time constant of the second RC circuit

Adjustable gain active pixel sensor

Abstract: An active pixel sensor. The active pixel sensor includes a photo-diode. The photo-diode conducting charge as a function of the intensity of light received by the photo-diode. The photo-diode includes a diode capacitance which collects charge conducted by the photo-diode which generates a photo-diode voltage. A switched capacitor is connected in parallel with the photo-diode when the photo-diode voltage drops below a pre-determined voltage potential. A capacitance of the switched capacitor adds to the diode capacitance when the switched capacitor is connected. The switched capacitor can be a gate capacitor. The active pixel sensor further includes electronic circuitry to allow a controller to sample the photo-diode voltage.

Bias voltage dependent field-emission energy distribution analysis of wide band-gap field emitters

Abstract: We have studied the origin of field emission from wide band-gap semiconductors by a combination of voltage dependent field-emission energy distribution and I–V measurements. For this purpose, tip-shaped molybdenum emitters were coated with 100–1000 nm thick layers of nominally undoped diamond and cubic boron nitride (c-BN) powders. Electron energy spectra revealed that significant band bending occurred due to field penetration into wide band-gap materials. Voltage drops on the order of several volts were measured across the coatings, for applied voltages on the order of 1 kV, and a cathode–gate distance of 500 μm. These voltage drops showed a linear dependence with the applied bias voltage for well-annealed diamond coatings and a strongly nonlinear behavior for unannealed diamond and c-BN coatings. In general, annealing of diamond coated Mo tips led to improved emission current stability and lower “turn-on” voltages due to the removal of oxide and the formation of conductive carbide layers between the met...

Carrier injection enhancement effect of high voltage MOS devices-device physics and design concept

Abstract: IEGTs are one of the promising candidates for replacing GTOs in high voltage applications in 4.5 kV range. The injection enhancement effect of IEGT structure with the deep trench MOS gate and/or the wide cell design successfully reduces the voltage drop in the N-base. In this paper, we discuss the device physics and design concept of the injection enhancement effect for not only the trench structure but also the planar structure.

Pulse charging method for rechargeable batteries

Abstract: This charging method repeatedly charges and suspends charging to pulse charge a rechargeable battery. Open circuit battery voltage is measured during periods of suspended charging and charging is resumed when the measured voltage drops below a specified voltage. When the period of suspended charging is longer than a specified time, open circuit battery voltage is compared to a minimum voltage. When the open circuit battery voltage is greater than the minimum voltage and the period of suspended charging is longer than the specified time, the battery is considered fully charged. When the open circuit battery voltage is less than the minimum voltage, even though the period of suspended charging is longer than the specified time, the battery is assumed to be removed from the system.

Led light system

Abstract: PROBLEM TO BE SOLVED: To reliably and continuously light an LED(light emitting diode) by reducing a capacitance of a capacitor used in a smoothing circuit and suppressing a ripple current flowing into the capacitor in an LED lighting system used in a luminaire equipped with an inverter ballast SOLUTION: This LED lighting system consists of a full wave rectifying circuit 41 to rectify a high frequency current from an inverter ballast, a smoothing capacitor 43 connected to the rectifying circuit through an inductance element 42 and an LED unit 44 in which n×m pieces of LED 11 connected to the smoothing capacitor are arranged If a current and a voltage drop are set for 1 min ampere and V min volt respectively at the time when the LED starts lighting and the maximum rated forward current and voltage drop are set for 1 max and V max respectively, the smoothing capacitor is set to have a capacitance to always maintain a higher output voltage than (n) v min and a lower voltage value than (n) V max when the LED is lighted, and the inductance element is set for a value to have a sufficient impedance value at a twice as much frequency from the ballast

Busbar design considerations for high power IGBT converters

Abstract: This paper addresses an important issue in the design and synthesis of high power IGBT converters, i.e. the layout and design of connection busbars. Parasitic inductance, caused by the physical distance current has to flow from the storage capacitors to the static switches and back, is the major constraint in developing a bus structure. This leads to nonideal converter operation, namely voltage overshoot, voltage drop and resonance with snubber capacitors. By analyzing the currents and fields in and around busbars, parasitic inductance can be predicted and limited.

Fully switched, class-B, high speed current amplifier driver

Abstract: A current amplifier driver capable of driving both 10 Base-T signalling and 100 Base signalling in a Local Area Network (LAN) includes one constant current source. A voltage controlled switch is contained in each of four vertical segment of an H-bridge circuit. Two voltage signals are applied to the switches to control the direction of current from a constant current source across a load. When one of the voltage signals is high, the other is low and two switches of the four switches turn on. The current amplifier driver sinks the constant current in a first direction, such that a voltage drop across the output nodes is positive. When the other voltage signal is high the switches that were on turn off, and the other two switches turn on to sink the constant current across the load in the opposite direction, such that a voltage drop across the output nodes is negative. When both voltage signals are low, all four switches turn off, and the output voltage is zero. In this manner, a differential signal is generated across a resistive load.

High-voltage tolerant input buffer in low-voltage technology

Abstract: An integrated circuit is implemented in a low-voltage technology and has an output driver. The output driver has circuitry adapted to generate an output voltage at an output node (e.g., PAD in FIG. 1) based on an input voltage (e.g., A). Within the output driver, a transistor is configured to limit the drain-to-source voltage drop across another transistor to enable the integrated circuit to tolerate, at its output node, voltages of magnitude up to two times the operating voltage of the integrated circuit. The invention enables low-voltage integrated circuits to be interfaced with other circuitry implemented in a relatively high-voltage technology, without suffering the adverse effects that can otherwise result in the low-voltage circuitry from such interfacing.

Measurement of the hot electrical conductivity in the pbx-m tokamak

Abstract: A new method for the analysis of tokamak discharges in which the plasma current is driven by a combination of high power RF waves and a DC electric field is presented. In such regimes, which are the most usual in RF current drive experiments, it is generally difficult to separate the different components of the plasma current, i.e. purely ohmic, purely non-inductive and cross terms. If the bilinear (in wave power and electric field) cross-term is the dominant one, an explicit relation between the loop voltage drop and the injected power can be found. This relation involves two parameters, the purely RF current drive efficiency and the hot (power dependent) electrical conductivity. These can be simultaneously determined from a simple two parameter fit, if the loop voltage drop is measured at several RF power levels. An application to lower hybrid current drive experiments in the Princeton Beta Experiment (PBX-M) tokamak is presented. It is shown that the method also allows independent evaluation of the average power absorption fraction and the n|| upshift

Circuit arrangement for operating electric lamps, and an operating method for electronic lamps

Abstract: The circuit arrangement according to the invention has a self-oscillating inverter having at least two alternately switching transistors (Q1, Q2), a load circuit connected to the inverter output and designed as a resonant circuit (L1, C1), and terminals for at least one electric lamp (LP). According to the invention, the control junction of a transistor (T1) is arranged in the emitter line of one of the inverter transistors (Q2). Via the variable conductivity of this control junction, the effective emitter resistance of the inverter transistor (Q2) is continuously varied as a function of the voltage drop across one of the resonant circuit components (C1), and the clock frequency of the inverter (Q1, Q2) is thereby increased so far that because of the now stronger detuning with respect to the resonant frequency of the resonant circuit (C1, L1) a reduction in the no-load voltage in the load circuit is achieved.

Series drive circuit

Abstract: A series drive circuit for driving a plurality of serially-connected electronic elements, such as electrochromic elements. The series drive circuit maintains a accurately controlled voltage across each of the electronic elements, while reducing power consumption and current consumption. A constant voltage is applied to the serially-connected electronic elements that is the sum of the required voltage for each of the electronic elements. In order to prevent excess voltage across any of the elements, shunts are connected in parallel with each of the elements. In order to reduce excess voltage across any of the elements, the voltage across each of the elements is monitored and used to control the shunts to maintain a accurately controlled voltage across each of the serially-connected electronic elements.

Circuit for measuring in-circuit resistance and current

Abstract: A circuit for measuring alternating current (a.c.) and direct current (d.c.) in a conductor without breaking the conductor is provided. A modulated current source is coupled in parallel with a segment of the conductor to inject a test current. A synchronous demodulator is also coupled in parallel across the segment to separate the test voltage drop induced by the test current from the voltage drop due to the current in the conductor. The test voltage drop and the voltage drop are measured by a voltmeter and the resistance of the segment and the current flowing through the segment can then be calculated.

Bandgap reference circuit

Abstract: A voltage reference circuit that will remain constant and independent of changes in the operating temperature that is correlated to the bandgap voltage of silicon is described The voltage reference circuit will be incorporated within an integrated circuit and will minimize currents into the substrate The bandgap voltage reference circuit has a bandgap voltage referenced generator that will generate a first referencing voltage having a first temperature coefficient, and a compensating voltage generator that will generate a second referencing voltage having a second temperature coefficient The second temperature coefficient is approximately equal and of opposite sign to the first temperature coefficient A voltage summing circuit will sum the first referencing voltage and the second referencing voltage to create the temperature independent voltage A voltage biasing circuit will couple a bias voltage to the bandgap voltage referenced generating means to bias the bandgap voltage referenced generator to generate the first referencing voltage The voltage biasing circuit has a first MOSFET configured as first diode having an anode coupled to the power supply voltage source, and a second MOSFET configured as second diode having an anode coupled to the source of the first MOSFET and a cathode coupled to the ground reference point The biasing voltage is developed at the connection of the cathode of the first diode and the anode of the second diode and said biasing voltage has a value a voltage drop across said second diode

Apparatus and method for controlling flow of power in a transmission line including stable reversal of power flow

Abstract: Power flow in a transmission line carrying alternating current is controlled by injecting into the transmission line in series a compensating voltage which is either in phase or 180° out of phase with a reactive component of the transmission line voltage. The compensating voltage is generated by a voltage source converter operated by a controller which determines the angle of the transmission line voltage from voltage measurements taken at spaced apart points on the transmission line. Operation of the inverter in this voltage control mode results in an increase in power flow when the compensating voltage is injected at 180° out of phase with the voltage across the transmission line effective reactance. When the compensating voltage is injected in phase with the voltage across the transmission line effective reactance, the power flow decreases at first from the uncompensated value and can be reduced to zero when the compensating voltage equals the voltage across the transmission line effective reactance without compensation. Further increase in the compensating voltage in the same direction reverses the direction of power flow.

Method and system of performing voltage drop analysis for power supply networks of VLSI circuits

Abstract: A method for testing for power supply network voltage drop violations in an integrated circuit through a computer simulation. First, the IC chip area is divided into a number of discrete regions. The simulation time is divided into a number of time segments. Next, the average aggregate currents corresponding to the transistors for each of the regions are calculated for each of the time segments. Only when a peak average current occurs for any one of the plurality of regions is the power supply network of the IC chip simulated for that time segment. Based on the voltage drops as determined by the power network simulation, violation conditions can be easily identified. Thus, the power network of the IC chip is simulated only when there is found to be high switching activity in some region of the chip. This is more efficient than performing power network voltage drop analyses all the time, even when switching activity throughout the chip is low and the likelihood of any voltage drop violations is very low.

The Integrated Gate-Commutated Thyristor: A New High-Efficiency, High- Power Switch for Series or Snubberless Operation

Abstract: A novel high power semiconductor switch is now commercially available. The IGCT combines in a unique manner the advantages of a thyristor, low on-state voltage drop and high blocking voltage ratings, with the rugged switching behaviour of the transistor. After a brief overview of the technology used, the main characteristics of the 5SHY 35L4502 are presented. Finally, examples for possible applications are given.

Multi-layer structured nitride-based semiconductor devices

Abstract: At an n--n hetero-interface in a GaN-based or ZnSe-based multilayered semiconductor laser and light-emitting diode, an excessive voltage drop causing the operating voltage to increased is reduced, thereby lengthening the service life of the device. A single or plurality of n-type intermediate layers are provided in the n--n hetero-interface region where the excessive voltage drop develops. The excessive voltage drop developing at the n--n hetero-interface is decreased by setting the energy value at the edge of the conduction band of each intermediate layer to a mid-value between the energy values at the edges of the conduction bands of the n-type compound semiconductors adjoining both sides of the intermediate layer. The configuration of a GaN-based MQW laser including the intermediate layer formed on sapphire substrate is shown. The relationship between the lattice constant of an intermediate layer necessary for obtaining an intermediate layer excellent in crystallinity suitable for the above object and the lattice constants of compound semiconductors adjoining both sides of the intermediate layer is described.