Showing papers on "Bridge circuit published in 1998"

A unity power factor converter using half-bridge boost topology

Abstract: A single-phase high-efficiency near-unity power-factor (PF) half-bridge boost converter circuit, which has been proposed earlier by other researchers, is presented with detailed analysis. This converter is capable of operating under variable PF. However, the focus of this paper is in achieving unity PF operation only. The efficiency of this circuit is high because there is only one series semiconductor on-state voltage drop at any instant. The existence of an imbalance in the voltages of the two DC-link capacitors, which was noted before, is confirmed here. The cause for the imbalance is analyzed using appropriate models, and a control method to eliminate it is discussed in detail. Analysis and design considerations for the power circuit using the fixed-band hysteresis current control (HCC) technique are provided. The analytical results are verified through simulation using switched and averaged circuit models of the scheme and also through experimental work. At 90-V AC input and 300-W 300-V output, the experimental prototype demonstrates an efficiency of 96.23% and a PF of 0.998. This converter, with its relatively high DC-output voltage, is well suited for the 110-V utility supply system. A circuit modification for universal input voltage range operation is also suggested.

PWN controller use with open loop flyback type DC to AC converter

Abstract: A controller and ring generator circuit realized therefrom utilizing an open loop flyback topology to achieve a desired output voltage waveform. A characteristic feature of the controller is that it provides the required signals to control a ring generator circuit having an open loop fly back topology. The controller functions to generate a PWM signal that is used to switch the primary of a transformer on and off. The controller includes the necessary functionality to control the duty cycle of the generated PWM signal so as to produce a sine wave output on the secondary of the transformer. The controller also includes overcurrent protection circuitry that tracks the load current by sensing the current through the primary winding. In addition, the circuit permits negative current in the secondary by use of a synchronous rectifier circuit coupled to an additional secondary transformer winding. An output bridge circuit creates a full sine wave from the generated half wave output.

Embedded Self-Sensing Piezoelectric for Damage Detection:

Abstract: A method for damage detection based on self-sensing piezoelectrics is presented. When a piezoelectric actuator is electronically excited, it causes stress in the structure to which it is attached. As the structure deformation is influenced by the presence of damage, so will be the response of the sensor. The goal of the method is to use the same piezoelectric element as both actuator and sensor, by analyzing the electromechanical response of the system in the frequency domain. In this way, damaged and undamaged structures can be distinguished and the extent of damage estimated. The distinction between the excitation and the response signals is achieved by an electronic bridge circuit. A comparison between this self-sensing method and the more common cross-talk method is performed, showing the similarity of the two methods and the validity of our technique. A method to differentiate among the spectrum changes due to actual damage and those due to temperature shifts is also presented. As the temperature ris...

Single phase motor drive

Abstract: A motor having a stationary assembly including a winding and a rotatable assembly in magnetic coupling relation to the stationary assembly. A bridge circuit for use in driving the motor has upper (54, 56) and lower (50, 52) power switches connected between the winding and the upper and lower rails (66, 68), respectively, of a power supply link. Each of the lower switches corresponds to one of the upper switches and each of the switches has a conducting state and a nonconducting state. The motor also has a control circuit for generating a motor control signal to control the switches. The lower switches are receiving and responsive to the motor control signal. A drive circuit (70, 72) drives the upper switches (54, 56) in response to the state of the lower switches to selectively connect the rails of the power supply link to the winding. As such, the winding is energized to produce an electromagnetic field for rotating the rotatable assembly relative to the stationary assembly. The drive circuit controls the upper switches to provide a delay interval between the conducting states of the corresponding upper and lower switches thereby reducing shoot-through currents.

Communication link with isochronous and asynchronous priority modes coupling bridge circuits in a computer system

Abstract: A computer system includes a first processor integrated circuit. A first bridge integrated circuit is coupled to the processor via a host bus. The computer system includes an interconnection bus that couples the first bridge circuit to a second bridge circuit. The interconnection bus provides a first transfer mode for asynchronous data and a second transfer mode for isochronous data. The interconnection bus provides for a maximum latency and a guaranteed throughput for asynchronous and isochronous data.

Drive unit for electric motor

Abstract: A drive unit for driving an electric motor includes two motor drive circuits disposed in parallel and each consisting of a bridge circuit of switching devices each incorporating a reverse blocking diode, a power switch provided between a power supply and each of the bridge circuits, and a function switch provided between the electric motor and each of the bridge circuits. In case of failure of one bridge circuit, the other bridge circuit is used to replace the failed bridge circuit, thereby continuing controlled operation of the electric motor. While these switches which are associated with one of the bridge circuits are closed, the switches associated with the other bridge circuit are kept open. This arrangement prevents the current from flowing from the power supply into the failed bridge circuit. The failed bridge circuit does not allow the electric motor to act as a generator even when any of the switching devices causes an ON fault.

Response of a poly(pyrrole) resistive micro-bridge to ethanol vapour

Abstract: In this paper the authors describe the behaviour of a silicon micro-bridge fabricated with four conducting polymer resistive elements (two active) in a CMOS-compatible process. The poly(pyrrole) (PPy) bridges were characterised using a precision analogue interface circuit with the constant-current drive and voltage off-set set by a Labview Virtual Instrument. The responses of eight polymer micro-bridges to ethanol vapour were recorded at different temperatures and humidity’s. The output voltage of the bridge circuit followed the classical Langmuir adsorption isotherm in concentration and generally fell with increasing temperature and humidity. A typical bridge sensitivity to ethanol of ca. 30 mV:ppm was observed at room temperature with the linear temperature coefficient of the operation being relatively high at 2.8 10 2 :°C. © 1998 Elsevier Science S.A. All rights

Transmission-line-based gyrator

Abstract: A new approach to efficient gyrator realization is described. The approach was motivated by the observation that a /spl lambda//4 segment of transmission line exhibits gyrator-like behavior. A gyrator that operates at low-frequency band, including dc, is formed by the combination of a /spl lambda//4 segment of transmission line and a switching network. Using a switching bridge, the low frequency signal is converted into a high-frequency wave which is applied to the input terminals of the transmission line. Then the original waveform is reconstructed using a second switching bridge. Since the switching bridge, as well as the transmission line, are loss free (in principle), the resulting gyrator is also lossless. Such a gyrator can find applications in power processing circuits. A circuit based on this approach was constructed and tested at the energy conversion laboratory, Tel-Aviv University, Israel.

Dynamic braking system for electric motors

Abstract: A dynamic braking system for a brushless motor (10) where energization of the motor winding is achieved through a transistor bridge circuit (14) wherein half of the switching transistors (30-32) are connected to a positive supply (36) and the remaining switching transistors (40-42) are connected to a negative supply (46). Back-biased diodes (33-35 and 43-45) are connected across each of the switching transistors. Dynamic braking is achieved by rendering all transistors connected to one of the supply sources (36, 46) conductive at the same time.

High performance internal bus for promoting design reuse in north bridge chips

Abstract: In an example embodiment, an apparatus providing communication in a computer system, comprises, a plurality of modules each having a master port and a slave port A secondary bus is shared between the plurality of modules for transmitting data and address information between a master port and a slave port of two modules. A bridge circuit coupled to the plurality of modules and the secondary bus, individually grants modules of the plurality of modules, access to the secondary bus. The bridge circuit establishes point-to-point communication paths between a master port and a slave port of two modules of the plurality of modules, for communicating handshake signals between them, and controls address and data phases between modules; two address phases can be outstanding simultaneously. The bridge circuit forwards address and data phases from one module to another module of the plurality of modules; the plurality of modules only interface with the bridge circuit.

Stacked I/O bridge circuit assemblies having flexibly configurable connections

Abstract: An I/O bridge system comprises a motherboard including first and second busses, e.g., first and second PCI busses. A I/O bridge circuit is connected between the first and second busses and operative to communicate therebetween. A first connector is disposed on a side of the motherboard and has the first bus provided thereat. A second connector is disposed on the side of the motherboard, positioned laterally adjacent the first connector and has the second bus provided thereat. An interconnected stack of daughterboards is disposed on the motherboard and connected to the first and second connectors of the motherboard. A daughterboard of the interconnected stack includes an I/O bridge circuit connected to one of the first bus or the second bus depending on the position of the daughterboard in the interconnected stack. The I/O bridge circuit is operative to communicate between one of the motherboard busses and a communications channel such as a Fibre Channel.

Failure diagnosing circuit and method

Abstract: To provide a failure diagnosing circuit capable of carrying out failure diagnosis of respective switching elements of a bridge circuit without rotating a motor. Pull up/down terminals and as well as monitor terminals are respectively connected to both input terminals of a motor. The pull up/down terminals selectively provide two states: a pull up state providing voltage 5 V for failure diagnosis to the motor input terminals via resistors and a pull down state providing ground potential to the motor input terminals via the resistors. A failure diagnosing circuit switches the two states of the pull up/down terminals, opens and closes any one element of switching elements and monitors a change in the potential of the monitor terminal corresponding to each of the combinations of switching the states and opening and closing of the switching elements by which failure diagnosis of the opened and closed switching element is carried out.

Method and circuit for monitoring the functioning of a sensor bridge

Abstract: The invention relates to a method for monitoring the functioning of a symmetrical sensor bridge circuit. According to the invention, the signal from the positive or negative half-bridge is subtracted from half of the bridge supply voltage (Vs/2) in a summing device (22) and subsequently amplified by an amplifier (3) to the extent that it corresponds to the full-bridge signal (Vin). Said full-bridge signal (Vin) is compared with the amplified differential signal in a comparator (5). In the event that the differential signal deviates unacceptably from the full-bridge signal (Vin), the comparator applies an alarm signal to the output signal (6) of the sensor so that said output signal takes up a signal range beyond the normal working range of the sensor.

Electromechanical Tuning of Self-Sensing Piezoelectric Transducers

Abstract: The application of a self-sensing piezoelectric transducer included in a bridge readout network is here investigated taking into account the electromechanical interaction. The parametric uncertainties and the piezoelectric device losses as well as the tolerances of the electric components make the balancing of the bridge difficult to achieve in practice. A loss and uncertainties compensation, based on a real-time software implementation of the bridge reference arm is here presented and validated. The standard electrical and the proposed electromechanical balancing are both theoretically and experimentally compared in the case of a simple beam. The bridge output signal that is proportional to the strain rate is then fed back by means of a sharp phase second order low pass filter which is aimed at increasing the damping of the first bending mode of the beam.

Ratiometric compensated optical isolation coupler

Abstract: An improved opto-isolator circuit is disclosed. A fixed bias current is induced through a photoemitter of the opto-isolator. A fixed DC voltage is fixed across the sensor of the opto-isolator, whereby any unknown scaling factor in the opto-isolator is substantially eliminated. In a low frequency embodiment, a passive bridge is used while in a high frequency embodiment, an active bridge circuit is used.

HVDC converter using self-commutated devices

Abstract: A three-phase bridge for a high-voltage direct-current (HVDC) converter which uses auxiliary (bypass) thyristor valves connected to tapping points on the transformer secondary windings has been previously described. The performance is enhanced by using self- or force-commutated devices for these valves, and three different schemes are examined. Experimental tests on a laboratory model validate the theoretical results. Fast and continuous control of the DC voltage is possible with a typical reduction of 20%-30% of the reactive volt-ampere (VAr) absorption compared with a conventional scheme. An additional feature of the scheme is that the transformer tap changer could have a reduced range with fewer taps or even be eliminated.

Method and apparatus for driving a sensorless DC motor having a bridge-type inductance detecting circuit

Abstract: A method and an apparatus for driving a sensorless DC motor having a bridge-type inductance detecting circuit. The method of driving a sensorless DC motor including a rotor having Y-winding phase coils and a plurality of magnetic poles comprises the steps of applying an alternating current voltage signal to bridge circuits coupled to the phase coils, respectively, inputting an output voltage signal of each bridge circuit as an inductance detecting signal of each phase coil, amplifying the inputted inductance detecting signal of each phase coil, comparing a value of the amplified inductance detecting signal of each phase coil to each other, and determining an initial position of the rotor for rotating the rotor, the phase coils except for a phase coil having a maximum inductance detecting signal being magnetized at the initial position. By the method, the initial position of the rotor can be precisely detected even when the rotor is rotated at a low speed or in a stop state, so the motor is reliably driven.

Method of controlling a chopper driver and a circuit arrangement for executing the method

Abstract: Depending on the desired direction of current flux through an electrical load such as a stepped motor, in a measuring bridge circuit provided with switchable semiconductors and recovery diodes the semiconductors through which the current direction is switched are closed, causing the actual current to increase until it has attained the nominal current value, whereupon switching is effected into either slow current decay mode or fast current decay mode. A selection of the operating mode is made at the next semiconductor switch-on such that, if the actual current value is greater than the nominal current value at the next semiconductor switch-off, fast current decay mode is selected, and if the actual current value is lower than the nominal current value, slow current decay mode is selected. For the remainder of the chopper period, for example until the next switch-on, the operating mode is no longer changed, or switching is effected once from fast current decay mode into slow current decay mode, as a function of a comparator device that compares actual current values and nominal current values, if the actual current value is lower than the nominal current value. The invention can be used in actuation electronics for stepped motors.

Strain gage bridge circuit with sensitivity equalization and method for sensitivity equalization

Abstract: A strain gage bridge circuit and method for sensitivity equalization, particularly suitable for load cell devices for precision measurement. The sensitivity of opposing half-bridges in a strain gage bridge circuit is equalized by a pair of equal, fixed resistors connected across a bridge diagonal formed by the two half-bridges, and a third resistor connecting the junction of the two equal, fixed resistors to the center of the half-bridge with the highest sensitivity. The effective shunting of the most sensitive half bridge can be changed by changing the value of the third resistor, while the ratio of the two equivalent shunting resistance values remain exactly constant. The total load on the bridge diagonal also remains constant when the value of the third resistor is changed. Both sets of orthogonally arranged opposed half-bridges in a strain gage bridge circuit can be equalized independently when two sets of equalizing resistors are used.

A modified temperature-compensation circuit for CTA

Abstract: Hot-wire anemometric measurements of non-isothermal flows require that temperature-compensation or correction systems should be applied A basic method of temperature compensation in a constant temperature anemometric bridge circuit involves an additional compensating sensor being connected into the bridge The resistance of the temperature-compensating sensor must be several times bigger than that of the anemometric sensor That is one of the major limitations of those sensors This paper presents some modification to the constant-temperature bridge system with temperature compensation A compensating sensor of any resistance may be applied there As a result, a wider group of measuring sensors may be used, which, in certain applications, may optimize measuring processes This modification consists of transformation of the voltage supplying the compensating branch of the anemometric bridge Special attention was given to the theoretical basis of temperature compensation Schematic diagrams of the measurement circuits as well as one selected application of the new system for a low-frequency case have been presented

Circuit arrangement for charging of DC voltage intermediate circuits via rectifier e.g.for static converters

Abstract: The circuit arrangement for charging a DC voltage intermediate circuit, is designed so that the charging current flows across a diode arrangement parallel to the thyristors (Th1-Th3) of a half wave controlled AC bridge circuit, and the thyristors are ignited, after the expiry of the charging operation. A charging resistance (R lade) lies in series to the diode arrangement (D1-D3). The ignition pulses of the individual thyristors are displaced to each other and this pulse pattern is continuously maintained, independent of the phase position of the mains voltage. The power for all thyristors is transmitted with a single transformer on the side subjected to a potential.

Circuit arrangement for controlling electric motor

Abstract: A circuit arrangement for controlling an electric motor 923) has switching devices provided by means of which the motor can be short-circuited. A bridge circuit consisting of at least four further switching devices is provided for controlling the motor in the bridge cross-branch. By operation of the further switching devices, one of the two bridge diagonals is switched to be current-conducting. An electrical resistance is provided via which the motor can be short-circuited by operation of the switching devices. The switching devices are designed at least as two controllable switches. They are designed as semiconducting relays.

Solenoid driver circuit for use with digital magnetic latching valves

Abstract: A solenoid driver circuit adapted for use with a digital magnetic latchingolenoid which has first and second solenoid coils. The solenoid driver circuit includes a bridge circuit which receives a logic signal and first and second pulse signals. The solenoid driver circuit also includes a voltage source which provides a direct current and first and second resistors respectively connected to the first and second solenoid coils. The bridge circuit, responsive to the logic signal and the first pulse signal, provides a first current path from the voltage source through the first solenoid coil and the first resistor to ground and a second current path from the direct current voltage source through the second solenoid coil to ground. The bridge circuit, responsive to the logic signal and the second pulse signal, provides a third current path from the direct current voltage source through the first solenoid coil to ground and a fourth current path from the direct current voltage source through the second solenoid coil and the second resistor to ground. The current flow through the current paths which include a solenoid coil and a resistor is approximately one amp, while the current flow through the currents paths which include only a solenoid coil is approximately twenty six amps. This allows for high speed control of the forces acting on the actuator of the solenoid.

Apparatus for measuring minority carrier lifetimes in semiconductor materials

Abstract: An apparatus (30) for determining the minority carrier lifetime of a semiconductor sample (32) includes a positioner for moving the sample relative to a coil (44). The coil (44) is connected to a bridge circuit (42) such that the impedance of one arm of the bridge circuit (42) is varied as sample is positioned relative to the coil (44). The sample (32) is positioned relative to the coil (44) such that any change in the photoconductance of the sample (32) created by illumination of the sample (32) creates a linearly related change in the input impedance of the bridge circuit (42). In addition, the apparatus (30) is calibrated to work at a fixed frequency so that the apparatus (30) maintains a consistently high sensitivity and high linearly for samples of different sizes, shapes, and material properties. When a light source (34) illuminates the sample (32), the impedance of the bridge circuit (42) is altered as excess carriers are generated in the sample (32), thereby producing a measurable signal indicative of the minority carrier lifetimes or recombination rates of the sample (32).

Gas sensor with multi-level sensitivity circuitry

Abstract: A combustible gas detector or sensors having a multi-level sensitivity circuitry. The gas detector has a bridge circuit for outputing voltages indicative of gas concentrations contacting the bridge circuit. There is a power supply node electrically coupled to one end of the bridge circuit. There is also a voltage control circuit, coupled between the bridge circuit and the power supply node, for controlling when at least a low and high input voltage level is supplied to the bridge circuit so that the bridge circuit has at least two levels of gas concentration discernability. The bridge circuit outputs distinguishable voltage levels for high gas concentrations in response to receiving the low voltage level. Additionally, the bridge circuit outputs distinguishable voltage levels for low gas concentrations in response to receiving the high voltage level.

Write-driver circuit

Abstract: In a write driver circuit for switching the direction of a write current passing through a magnetic head or the like having an inductance component, an H-shaped bridge circuit is formed by using four NPN transistors in order to switch the write current at a high speed. Four switching means for controlling the base potentials of the four NPN transistors are provided and two switching means for rapidly decreasing the base potential of one of the two NPN transistors on the power source side, which is turned off when the write current passing through the magnetic head is switched are provided, thereby widening a voltage difference occurring between both terminals of the magnetic head.

Eddy-current flow detecting probe

Abstract: PROBLEM TO BE SOLVED: To provide an eddy-current flow detecting probe which not only reduces a normal lift-off signal, but also an oblique lift-off signal. SOLUTION: An eddy-current flow detecting probe is composed of four detecting coils 1, an exciting coil 2, an oscillator 3, and a bridge circuit 4. The coils 1 are positioned to the apexes of a rhombus and, at the same time, each two diagonal coils 1 are Connected in opposite phases and, in addition, these two sets of coils are differentially connected to each other. The exciting coil 2 is constituted by combining coils which generate eddy currents obliquely flowing through an object to be tested near the coil centers of the two sets of detecting coils 1 with together. The oscillator 3 supplies an alternating current to the coil 2 and the bridge circuit 4 only fetches flaw signals from the differentially connected detecting coils 1.

Supply voltages switch circuit

Abstract: A circuit for switching between supply voltages and in particular for non-volatile flash memory devices and of the type comprising a first and a second circuit branch each incorporating a pair of transistors connected in series provides that at least one branch of the circuit be structured with a bridge circuit made up of P-channel MOS transistors. The bridge is made of a first and a second pairs of transistors connected between a first supply voltage reference and a common node. The first pair comprises transistors bigger than the transistors of the second pair while between the transistors making up the second pair is inserted a pair of resistors. Between the pair of resistors there is an interconnection node connected to a corresponding interconnection node between the transistors of the first pair.

Failure diagnostic method for motor driving circuit and device therefor

Abstract: PROBLEM TO BE SOLVED: To provide a failure diagnostic device which can detect any failure without any supply of current and to accomplish reduction in weight and in a cost of this kind of device. SOLUTION: This failure diagnostic device is fitted in a reversibly rotatable motor driving circuit 1, in which a driving object motor M is connected to a valance position in a bridge circuit consisting of switching elements Q1-Q4. In this case, the switching elements Q1-Q4 constituting the bridge circuit are operated so that a given measurement condition is accomplished, and an electric potential of a predetermined one side terminal M+ of the driving object motor M is measured, and then, a failure position of the motor driving circuit 1 is determined on the basis of the measuring condition and the one side terminal electric potential measured in compliance with the measuring condition.

Circuit for monitoring the ignition system for a safety device in an automobile

Abstract: A circuit with which errors in the triggering circuit can be very reliably detected has a transistor bridge circuit in whose shunt arm a triggering arrangement and a capacitor are arranged. A measured current source is connected to the transistor bridge circuit. A controller controls the transistors and the measured current source during a monitoring cycle so that the capacitor is charged by a measured current. A sample-and-hold circuit controlled by the controller measures, after the capacitor has been charged, a first voltage drop across the triggering circuit and, after the measured current has been turned off, a second voltage drop across the triggering circuit so that the controller can determine the resistance of the triggering arrangement and the capacitance from these two voltages.