Showing papers on "Voltage regulator published in 1992"

Apparatus for generating ultrasonic oscillation

Abstract: The apparatus includes an ultrasonic transducer having a hand piece, an ultrasonic vibrating element secured to the hand piece and a probe coupled with the hand piece for propagating the ultrasonic oscillation produced by the ultrasonic vibrating element, a driving circuit for producing a driving signal for the ultrasonic vibrating element, a voltage controlled amplifier for amplifying the driving signal, an impedance matching transformer having a plurality of primary windings connected to the output of the voltage controlled amplifier via a switching circuit and a secondary winding connected to the ultrasonic vibrating element, a probe identification circuit for detecting the probe connected to the hand piece to produce a probe identification signal, a feedback control loop for generating a control voltage which is applied to the voltage controlled amplifier for controlling the amplification factor thereof in accordance with a driving current of the driving signal, an impedance detecting circuit for detecting the impedance of the ultrasonic transducer and controlling, the switching circuit such that a given primary winding is connected to attain the impedance matching between the driving circuit and the ultrasonic transducer, and a voltage limiter arranged in the feedback control loop such that the maximum value of the control voltage is limited in accordance with the probe identification signal.

Switched mode power supply integrated circuit with start-up self-biasing

Abstract: An embodiment of the present invention is a switching power supply that includes a full-wave bridge rectifier to rectify incoming AC line voltage, a transformer having a primary winding and two secondary windings and a switched mode power supply chip that includes an integrated high voltage power MOSFET with a low voltage tap in the drift region. The MOSFET controls power switching of the primary winding of the transformer and has a high voltage present during initial power-up. This high voltage is dropped across the JFET part of the MOSFET and supplies a regulator with power either temporarily or continuously to operate a pulse width modulator in the chip that controls the switching of the MOSFET.

The application of network objective functions for actively minimizing the impact of voltage harmonics in power systems

Abstract: The impact of voltage harmonics on a power system can be minimized by using active filters to inject distortion-canceling currents. However, a network objective function must be specified before the optimum filter injection currents can be determined. The authors illustrate the application of a distortion-minimizing procedure with each of the following four network correction strategies, total harmonic voltage distortion, telephone influence factor, motor load-loss function, and single-bus sine wave correction. It is also pointed out that, as with any active device, care must be taken when sitting and controlling an APLC (active power line conditioner) to ensure maximum improvement in network distortion. If a network approach is not used, a poorly located APLC could have an overall negative impact. >

Uninterruptible power supply with improved output regulation

Abstract: A microprocessor based uninterruptible power supply generates an AC electrical output power from an AC input source when the AC input source is within settable voltage limits and from an auxiliary source of DC power when the AC input source is outside said the voltage limits. The microprocessor provides monitoring of the AC input voltage to determine its amplitude and frequency, and uses this information to set the magnitude and frequency of the AC output voltage and to select the source of the AC output power. A power factor improvement circuit boosts the selected source to a high DC voltage which is inverted by a chopper circuit to produce a high frequency AC voltage is rectified and sent to a PWM inverter to produce the AC output power. An average current feedback loop provides the output voltage regulation and utilizes current limiting to provide output current limiting for protection against short circuits and overloads. A voltage phase relationship is maintained between the AC input power and AC output power to eliminate voltage and current transients at transfer times between the AC and DC input sources. A serial data communications port sends data sent over a network that includes signals indicative of the status of the uninterruptible power supply and receives data from the network for controlling operation of the uninterruptible power supply.

Physical origins of input filter oscillations in current programmed converters

Abstract: Addition of an input filter to a current-programmed converter can cause the controller to oscillate. Two instability mechanisms can typically occur: (1) the current programmed controller effective current feedback loop may become unstable, or (2) the controller effective input voltage feedforward loop, which becomes a positive feedback loop when an input filter is added, may oscillate. Three design criteria for preventing oscillations are derived and interpreted. When all three criteria are well satisfied, then the output voltage regulation loop gain is unchanged. Hence, input filters of current programmed converters can be designed in essentially the same manner as for duty-ratio programmed converters. Results are summarized in tabular form for the basic buck, boost, and buck-boost converters. Experimental measurements for a buck converter with different input filters support the theoretical predictions. >

Digital models of coupling capacitor voltage transformers for protective relay transient studies

Abstract: The authors describe the development by EPRI of digital coupling capacitor voltage transformer (CCVT) models that are intended for digital simulation of fault transients Experimental techniques for laboratory measurements of the CCVT parameters are outlined A sensitivity study was performed to identify the influence of various CCVT parameters on the transient behavior relevant for the relaying studies Digital models of three different CCVTs are given and their transient behavior is compared to the behavior of the actual transformers >

Power system for parallel operation of AC/DC converters

Abstract: A plurality of AC/DC converters (11) connected in parallel, are provided in which any one of the power converters can fail with-out affecting the operation of the machine which the plurality of converters are providing power. The failed AC/DC converter can be removed and replaced by another converter without shutting down the system. The output voltage of each converter is sensed on the power supply side of a decoupling diode (17, 19, 21). This allows each one of the converters to operate with its own sense loop (25, 27, 31, 33, 35, 41, 43) and, therefore, the feedback loop does not open when a converter is removed and another used in its place. Via power limit circuit (45) each of the parallel connected AC/DC converters (11) is designed to provide a preset maximum power which is independent of AC line voltage variation. To limit the power, the control voltage is made inversely proportional to the average input AC line voltage. The output voltage of the AC/DC converter is made to vary as a function of the load. This allows all the converters in parallel to provide power to the load all the time.

Quick-start and overvoltage protection for a switching regulator circuit

Abstract: A switching regulator controls the pulse width to a gate of a switching power transistor to maintain an average output voltage. An error amplifier in the regulation loop detects the difference between the actual output voltage and its desired value and maintains the proper regulation voltage at a loop node to control the pulse width to the gate of the power transistor. A quick-start circuit establishes a minimum loop regulation voltage at the loop node during power up allowing the error amplifier to begin regulating immediately thereby reducing start-up delay. The quick-start circuit is disabled after the loop node reaches the minimum loop regulation voltage. The switching regulator also monitors the output voltage by the same input pin to detect an overvoltage condition and shuts down the power switching transistor accordingly.

Voltage interfacing buffer with isolation transistors used for overvoltage protection

Abstract: A voltage interfacing buffer for interfacing a low voltage integrated circuit to a high voltage environment, wherein the integrated circuit contains only low voltage transistors. To drive the high voltage environment at the low voltage swing, the voltage interfacing circuit employs protection circuits and novel n-well biasing of MOS transistors. To drive the high voltage environment at the high voltage swing, the voltage interfacing circuit employs a bias generator circuit to bias buffer transistors supplied with the high voltage. As example applications, the voltage interfacing buffer enables a 3 volt or 3.3 volt integrated circuit chip to drive TTL as well as CMOS voltage levels. Moreover, the voltage interfacing buffer enables a 2 volt integrated circuit chip to drive TTL voltage levels.

On time control and gain circuit

Abstract: A voltage regulating control loop for a boost converter having a gain stabilizing stage is provided. The gain stabilizing stage makes the open-loop AC gain independent of the DC output of the boost converter and of the root mean square value of the 50/60 Hz line input voltage. The gain stabilizing stage generates an error voltage that is proportional to the square root of a voltage that is a function of the DC output current divided by the root mean square value of the 50/60 Hz line voltage. The error voltage is compared to the integrated value of a signal inversely proportional to the error voltage to the on time of the power stage FET.

Reactive power compensator.

Abstract: A system and method for determining and providing reactive power compensation for an inductive load. A reactive power compensator (50, 50') monitors the voltage and current flowing through each of three distribution lines (52a, 52b, 52c), which are supplying three-phase power to one or more inductive loads. Using signals indicative of the current on each of these lines when the voltage waveform on the line crosses zero, the reactive power compensator determines a reactive power compensation capacitance that must be connected to the lines to maintain a desired VAR level, power factor, or line voltage. Alternatively, an operator can manually select a specific capacitance for connection to each line, or the capacitance can be selected based on a time schedule. The reactive power compensator produces control signals, which are coupled through optical fibers (102/106) to a switch driver (110, 110') to select specific compensation capacitors (112) for connections to each line. The switch driver develops triggering signals that are supplied to a plurality of series-connected solid state switches (350), which control charge current in one direction in respect to ground for each compensation capacitor.

Automated voltage and VAR control in power transmission and distribution networks

Abstract: Controlling a customer voltage and VAR flow in a power transmission and distribution system includes measuring first voltages in a power line directed to a first location related to customers. Both the customer voltage and the VAR flow for the network is determined in relation to the number of capacitors associated with the first location which are switched in or out of the network. The measured voltages are communicated to a voltage control. Voltage deviations of the measured first voltage are determined relative to a predetermined voltage range intended to be present at the first locations. Switching the capacitor means into or out of the network is determined by the voltage control in accordance with a voltage rise table. A VAR flow controller is responsive to the voltage at the first locations, the effect of the VAR generation by the capacitors and the change of VAR generation by the capacitor. A decrease in voltage at the customers saves energy use. A decrease in the VAR generated upstream of the customer results in greater efficiency of energy generation.

Input filter design criteria for current-programmed regulators

Abstract: The design of input filters for switched-mode regulators is discussed, and it is shown that the filter's effect on the power system depends on the control method used in the regulator's DC-DC converter. Design inequalities are reviewed for duty-ratio programmed converters, and specific expressions are presented for current-programmed converters. Examples of application to practical regulator circuits are given where current-programmed criteria, computer-driven measurement tools, and numerical evaluations of analytic expressions are used to design input filters. >

Constant voltage circuit formed of FETs and reference voltage generating circuit to be used therefor

Abstract: A constant voltage circuit formed of MOS transistors is provided, which comprises a reference voltage generator and an error amplifier performing the temperature compensation of a reference voltage outputted from the reference voltage generator and outputting a constant voltage. The reference voltage generator comprises first, second and third MOS transistors each driven by a constant current source, and outputs the reference voltage to the connecting end with the error amplifier. The error amplifier includes a differential pair of fourth and fifth MOS transistors whose capacity ratio is 1:K1, and an active load composed of sixth and seventh transistors whose capacity ratio is 1:K2. One of input pair of the differential pair is applied with the reference voltage and the other thereof is applied with a voltage obtained by dividing the constant voltage. The output voltage of the differential pair is outputted to the outside as the constant voltage from an output circuit including resistors for dividing the constant voltage.

Charge pump with symmetrical +V and -V outputs

Abstract: Charge pump circuitry is implemented using a voltage shifting technique to generate a symmetrical bipolar voltage. The symmetrical bipolar voltage charge pump power supply can be fabricated as an integrated circuit on a single substrate, and can be integrated with various interface circuits to provide symmetrical bipolar voltage thereto. The charge pump includes voltage shifting circuitry which generates an increased output voltage of a negative polarity and an increased output voltage of a positive polarity. The shifting circuitry is responsive to an internal oscillator which triggers charge accumulation and voltage shifting. Neither output voltage is generated from the other output voltage. Rather, the negative and positive supply voltages are each generated, in substantially the same manner, by charge transfer effected by the voltage shifting circuitry in response to triggering by the internal oscillator. Additional circuitry can be fabricated on a single substrate in combination with the presently disclosed charge pump to effect the optimum utilization of circuit board area while minimizing power consumption.

controllable bus terminator

Abstract: A controllable bus terminator for providing a switchable termination on a bus having a plurality of conductors, wherein the controllable bus terminator includes a voltage regulator, a plurality of termination networks, each having a first terminal and a second terminal wherein the second terminal of each of the termination networks provides an output terminal of the bus terminator The bus terminator further includes a plurality of electrically controllable switches, each of the switches having a first port coupled to the voltage regulator and a second port coupled to the first terminal of a corresponding one of the termination networks wherein each of the switches couples the corresponding termination network to the voltage regulator when the corresponding switch is in a first state and wherein each of the switches disconnects the corresponding termination network from the voltage regulator when the corresponding switch is in a second state

Split gradient amplifier for an MRI system

Abstract: A gradient amplifier for use in magnetic resonance imaging equipment employs a low voltage DC power supply connected in series between a pair of higher voltage DC power supplies, the latter supplies serving to provide increased power for rapid gradient switching and the former supply providing correction current to produce the desired voltage output. The high voltage DC power supplies preferably comprise multiple DC units which can be combined to provide finer steps of control prior to correction by the lower voltage supply. The low voltage DC power supply preferably comprise one or more linear amplifiers connected in series, or one or more switchmode amplifiers connected in series. The DC power supplies are controlled in an open loop manner from a gradient signal that designates the desired current for the gradient coil and the amplifiers are operated in a closed loop responding to to a feedback signal from the gradient coil.

Multiple-voltage control circuit of battery or multiple independent DC power

Abstract: Circuit of multi-voltage control circuit of battery of multiple independent DC power consists of a diode compound switch contact for resisting sparkle and segmented current when multi-voltage switches add the non-sparkle switch for series of solid switch member which forms linear voltage adjustment of basic grade and voltage of low loss, or chopped wave voltage adjustment of low pulse. The advantages of the present invention are that it loses less thermal, is highly efficient, and has low pulse. It can provide fine quality graded voltage and a voltage adjustment between further grades.

Power inverter for generating voltage regulated sine wave replica

Abstract: A power inverter formed by several transformers having their secondary windings wired in series and their primary windings connected to respective switching bridges. The turns ratios of each of the primary windings vary from each other by a factor of 3 to provide good voltage resolution over a wide dynamic range. The switching bridges are controlled by a decoder and timing circuit which is, in turn, controlled by a microprocessor. The microprocessor closes the switches in the switching bridges in up to 27 different combinations to produce 27 different output voltages, thereby generating a relatively accurate replica of a sine wave. Voltage regulation is accomplished by sampling the A.C. voltage, comparing the magnitude of the A.C. voltage to a reference voltage, and adjusting the selection of output voltage values so that the A.C. voltage matches the reference voltage. The switching bridge may also be controlled to convert an A.C. voltage applied to the transformer secondaries to a D.C. voltage for battery charging purposes.

Low-drop voltage regulator

Abstract: A voltage regulator comprising a first power switch connected between the input terminal and output terminal; a storage condenser connected to the input terminal via a one-way switch; a second power switch connected between the condenser and the input terminal; and a regulating element connected to the output terminal and driving the power switches in such a manner as to maintain the output voltage constant. For better distributing electric and thermal stress and improving the reliability and working life of the regulator by reducing the interference caused by switching of the two power switches, a drive device is provided between the regulating element and the switches for detecting the input voltage and the voltage of the condenser, and keeping both switches on as long as the input voltage is above two given thresholds, turning off the second switch when the input voltage is higher than the condenser voltage and below the first threshold, and turning off the first switch when the input voltage is lower than the condenser voltage and below the second threshold.

Electric power system for marine vehicles

Abstract: An electric power system for large marine vehicles in which one or more AC generators are shared as the ship's propulsion power source and the ship's electrical service power source. The voltage from the AC generator(s) is rectified to a reduced DC voltage such that voltage transients in the propulsor motor do not reflect into the ship service power system. Silicon controlled rectifier (SCR) bridges are utilized to convert the generator's AC voltage into a reduced DC voltage. As a supplement for emergency power, a rechargeable battery is included to provide power for propulsion and ship service.

Voltage regulator for field programmable gate arrays

Abstract: A voltage regulator especially adaptable for use with field-programmable gate arrays (FPGA). The voltage regulator is configurable as a true voltage regulator or, alternatively, as a pseudo-voltage regulator. The voltage regulator includes circuitry to rapidly generate an operating voltage for the core or nucleus logic elements. Additional circuitry is provided to reduce the steady-state power consumption once the operating voltage is reached. To compensate for die-to-die variations, additional circuitry is also provided to adjust the compensation delays or switching rates.

Power supply apparatus for a vehicle having batteries of different voltages which are charged according to alternator speed

Abstract: A power supply apparatus for a vehicle includes an alternator for generating an output voltage for charging a first battery and a second battery having a higher voltage than the first battery. The output voltage of the alternator is controlled by a voltage regulator in accordance with the rotational speed of the alternator. When the rotational speed is in a low speed range, the voltage regulator controls the output voltage of the alternator to a first value suitable for charging the first battery. When the rotational speed is in a high speed range, the voltage regulator controls the output voltage of the alternator to a second value higher than the first value and suitable for charging the second battery. The output voltage of the alternator is switched between the first value and the second value at a rotational speed at which the output power of the alternator at the first output voltage equals the output power at the second output voltage. The apparatus may include a voltage converter which reduces the output voltage of the alternator to a voltage suitable for charging the first battery when the alternator is generating power at the second voltage. Alternatively, when the alternator is generating power at the second voltage, a point of the armature winding of the alternator having a voltage less than the output voltage of the alternator may be connected to the first battery to charge the first battery.

High voltage dc-dc converter with dynamic voltage regulation and decoupling during load-generated arcs

Abstract: A high-power power supply produces a controllable, constant high voltage output under varying and arcing loads. The power supply includes a voltage regulator, an inductor, an inverter for producing a high frequency square wave current of alternating polarity, an improved inverter voltage clamping circuit, a step up transformer, an output rectifier for producing a dc voltage at the output of each module, and a current sensor for sensing output current. The power supply also provides dynamic response to varying loads by controlling the voltage regulator duty cycle and circuitry is provided for sensing incipient arc currents at the output of the power supply to simultaneously decouple the power supply circuitry from the arcing load. The power supply includes a plurality of discrete switching type dc--dc converter modules.

Multi-battery charging system for reduced fuel consumption and emissions in automotive vehicles

Abstract: A multi-battery charging system for reduced fuel consumption and emissions for an automotive vehicle. The system starts the vehicle with a start battery in a fuel saving manner, removing electrical torque from the alternator shaft, and allows a second (run) battery to provide all or some of the current required by the vehicle loads as a fuel savings measure. The start battery is recharged after start and switched out of the system fully charged for future vehicle starts. The run battery is recharged when its charge level drops below a predetermined level with an on board battery charging device powered from a 115 volt or 220 volt ac power line source external to the vehicle. The system also increases the alternator field current to charge the run battery during vehicle deceleration to use vehicle momentum to torque the alternator shaft, thus saving fuel. The system controls the alternator field current with a voltage regulator. The voltage regulator senses the charge level of the run and start batteries and vehicle operating conditions and provides the proper current into the alternator rotor for maximum fuel savings. The voltage regulator may be a non-microprocessor or a microprocessor controlled device.

Ripple-free phase detector using two sample-and-hold circuits

Abstract: A phase detector comprises a ramp voltage generator for receiving a reference pulse of a constant frequency and an input pulse and producing a ramp voltage proportional to the phase difference between these pulses. A first sample-and-hold circuit samples the ramp voltage in response to a sampling pulse and holds the sampled voltage. To eliminate ripple component, a second sample-and-hold circuit is provided, which is also responsive to the sampling pulse for sampling a voltage from a constant voltage source and holding the sampled voltage. The voltages sampled by the first and second sample-and-hold circuits are input to a subtractor where the voltage difference between the two input voltages is detected. Ripple components generated by the two sample-and-hold circuits are cancelled out by the subtractor.

Switched capacitor transducer

Abstract: A micromachined accelerometer includes two capacitors comprising a pair of fixed capacitor electrodes and an intermediate movable proof mass serving as a common electrode which is displaced under acceleration to differentially vary the capacitances. A circuit holds the common electrode at a bias voltage and a switching circuit rapidly alternating between two phases separately connects the fixed electrodes to a main reference voltage and to ground during a first phase and to a common intermediate voltage during a second phase. A charge amplifier senses capacitance changes due to acceleration to produce an output voltage and an attenuating amplifier responsive to the output voltage produces the common intermediate voltage. A compensation servo circuit responsive to the output voltage generates the bias voltage which controls an electrostatic balancing force which is applied to the proof mass during the first phase to maintain the proof mass near a rest position. Alternatively, the bias voltage is a constant value for open loop operation.

Dual generator electrical system

Abstract: A motor vehicle power supply system for supplying current to the direct voltage loads on a motor vehicle. The system has two alternating generators which are driven by the engine of the motor vehicle. The output windings of the respective generators are connected to bridge rectifiers that supply current to a common motor vehicle direct current load. Each generator has a field winding and the current supplied to a respective field winding is controlled by a respective voltage regulator. The voltage regulators cause pulses of current to be supplied to the field windings. The system has a control circuit for controlling the pulse width of the current pulses supplied to the respective field windings such that the pulse width of the current pulses supplied to one field winding are substantially equal to the pulse width of the current pulses supplied to the other field winding.

Analysis and design of a series voltage compensator for three-phase unbalanced sources

Abstract: Voltage unbalance typically present in three-phase AC supply systems adversely affects power system components, static converters, drive systems, electric machines, etc., connected to the system. A method to eliminate this unbalance by means of a voltage compensator connected in series with the supply through transformers is described. The technique is based on extracting the negative sequence voltage component of the supply and canceling it in order to obtain balanced voltages. The positive sequence component is then adjusted to achieve voltage regulation. It is shown that the compensation can be achieved with low kilovolt-ampere inverters and that harmonic injection is reduced to a minimum. The authors include implementation principles, design equations, and a design example. Simulated and experimental results confirm the theoretical concept and feasibility of the proposed system. >

Average current mode control apparatus for an AC output amplifier

Abstract: A current mode control apparatus generates an AC power output from a DC input source. The apparatus includes a pulse width modulator (PWM) to produce gate drive signals for driving a power output section having an output inductor and connected across the DC input source. An inner current error control loop coupled between the AC power output and the PWM, controls the average current in the output inductor by generating a current error signal for inputting to the PWM for conversion to the gate drive signals. The current error signal is the difference between the average current and a voltage controlled input signal. An outer voltage error control loop coupled between the AC power output and the inner current error control loop generates a voltage error signal based on the difference between the AC power output and a reference AC voltage. The voltage error signal represents a change in demand for current in the output inductor and serves as the voltage controlled input signal to the inner current error control loop. A voltage limiter in the outer voltage error control loop limits the voltage error signal to a maximum value to prevent the average current in said output inductor and thus in said AC power output from exceeding a predetermined limit. The current mode control apparatus is adaptable for use in an uninterruptible power supply for supplying a load with the AC power output.