Abstract: For use in a power converter having a power switch subject to switching losses and a rectifying diode subject to a reverse recovery condition, a snubber circuit and related method to mitigate adverse effects associated with the switching losses and the reverse recovery condition. In one embodiment, the snubber circuit includes a recovery circuit, having first and second energy storage devices and a snubber diode, coupled to the rectifying diode. The snubber circuit further includes a third energy storage device, coupled across the rectifying diode, configured to cooperate with the recovery circuit to mitigate adverse effects associated with the reverse recovery condition and reduce a rate of change of a voltage across the power switch to reduce the switching losses.

Abstract: An externally-driven synchronous rectifier circuit (18) comprises first and second synchronous rectifiers (SQ1, SQ2), and first and second synchronous rectifier recovery switches (SQ3, SQ5), and a pair of resonant inductors (LR1, LR2). The resonant inductors (LR1, LR2) store the energy normally loss during charging and discharging the input capacitance of the first and second synchronous rectifiers (SQ1, SQ2). The recovery switches (SQ3, SQ5) transfer the stored energy from the at least one inductor (LR) to the output terminal (Vout) creating a more energy efficient circuit (18).

Abstract: A filter for an inrush relay, the relay having a relay coil having first and second leads includes a common-mode inductor connected to the relay coil leads across the relay coil. A first capacitor is connected to the first relay coil lead and a chassis ground potential. A second capacitor is connected to the second relay coil lead and the chassis ground potential. A third capacitor is connected to the relay coil leads across the relay coil. A first resistor is connected to the first relay lead, and a second resistor is connected to the second relay coil lead. The inductor and first and second capacitors form a high frequency common-mode filter. The third capacitor and first and second resistors form a high frequency differential mode filter.

Abstract: A rush current limiting device capable of restraining increased power consumption and heat generation caused by resistance for limiting rush current, and effectively limiting rush current caused on any conditions has. A resistance for limiting rush current caused by switching of a power switch between a rectifier diode bridge and a smoothing condenser. A triode AC switch and the relay are provided in parallel with the resistance. The on-operation of a power switch is monitored by the input monitoring circuit, and an triode AC switch is turned on at the zero crossing point of input signals after the on-operation by the zero crossing circuit to short-circuit the resistance. After a delay of the relay due to sensitive time, the relay is turned on by a relay driving circuit, and the triode AC switch is turned on.

Abstract: The present invention relates to an electric power unit with a condenser input type rectification circuit which converts an alternating current power source to a direct current voltage, and more particularly, to an electric power unit for inverter-controlled refrigerators.An electric power unit according to the present invention feeds electric power to a load (7), which comprises an alternating current power source (1), a bridge-type rectification circuit (2) having an input from the alternating current power source (1) and consisting of bridge-connected diodes (D1, D2, D3, D4), an auxiliary capacitor (3) connected in parallel to an output of the bridge-type rectification circuit (2), a series circuit of a reactor (4) and a diode (5) connected between one output of the bridge-type rectification circuit (2) and the load (7) so as to flow a load current in a forward direction, and a smoothing capacitor (6) connected in parallel to the load (7).

Abstract: A flyback converter including a transformer (T.sub.r), having a primary winding (W.sub.P) and having a secondary winding (W.sub.S), wherein the primary winding is connected in series with a controlled switch (T) and an actuation circuit (A) to an input direct voltage (U.sub.P), and the secondary winding is connected in series with a rectifier (D.sub.S) and, downstream of the secondary winding, a charging capacitor (C.sub.S); the actuation circuit (A) supplies start pulses of a fixed frequency for the switch, has a current sensor (R.sub.P) for the current through the primary winding. Coupled with the secondary winding is a first rectifying amplifier (K.sub.U) for comparing the output voltage (U.sub.S) with an adjustable voltage reference value (U.sub.RefU) and a second rectifying amplifier (K.sub.I) for comparing the output current (I.sub.S) with a adjustable current reference value (U.sub.

Abstract: The present invention relates to a snubber circuit, a voltage converter circuit as well as a method where the voltage converter circuit comprises a coupling element (DF), which can be influenced to conduct and not to conduct and across which the snubber circuit is connected, which comprises a first series circuit comprising a first capacitor (C1) and a first diode (D1) in parallel with at least one second series circuit comprising a second capacitor (C2) and at least one second diode (D2). All capacitors in the snubber circuit form a capacitive series circuit in parallel with the coupling element (DF), which has its beginning in the first capacitor (C1).

Abstract: An electric power converter having an AC input and AC output, and comprising a power rectifier and a power inverter having a DC three-wire circuit, wherein means for detecting a current or a voltage is connected between the AC power source and ground. When a current or a voltage is detected, an alarm is produced or the apparatus is halted. This makes it possible to judge whether the power inverter is in a state capable of producing an excessively large potential.

Abstract: For use with a power converter having a power supply control circuit, a current startup bias circuit and a method of operating the same. In one embodiment, the circuit includes: (1) a charge reservoir that receives and stores a trickle current during a startup period of the power converter, a voltage of the charge reservoir increasing as the charge reservoir stores the trickle current and (2) a latch, coupled to the charge reservoir, that activates when the voltage reaches a threshold to couple the charge reservoir to the power supply control circuit and initiate operation thereof.

Abstract: A snubbing network is provided for reducing electromagnetic ("EM") radiation from and power dissipation of a lamp discharge ballast. The snubbing network employs at least one active device. That device being a switch coupled in parallel with the modulating switch within a converter of the ballast. The snubbing switch, in conjunction with a current limiting inductor, and a voltage change rate limiting capacitor serve to substantially eliminate reverse recovery current within a freewheeling diode of the converter prior to closing the larger (modulating) switch. Reducing the reverse recovery current before closing the modulating switch helps minimize power dissipation during switch closure. A benefit of reduced power dissipation is a reduction in EM radiation from the lamp ballast to noise sensitive electronic components placed nearby.

Abstract: For use in a power supply having a rectifying diode and a snubber circuit that includes a snubber inductor for absorbing a portion of a reverse recovery current associated with the rectifying diode, a circuit and method for resetting the snubber inductor and a power supply employing the circuit and method. In one embodiment, the circuit includes a reset capacitor, coupled to the snubber inductor, that has sufficient capacity to impress a resetting voltage across the snubber inductor. The circuit also includes an activation circuit, coupled between the reset capacitor and an output of the power supply, that creates a voltage differential between the reset capacitor and the output to allow the reset capacitor to attain the resetting voltage.

Abstract: For use in a power system having a power train, a rectifier having an input and an output and a method of controlling the rectifier. The rectifier comprises: (1) switching circuitry coupled between the input and the output, the switching circuitry adapted to operate in selected one of (a) a bidirectional mode of operation and (b) an unidirectional mode of operation to rectify substantially alternating current at the input to produce substantially direct current at the output; and (2) control circuitry coupled to a control input of the switching circuitry, the control circuitry capable of sensing a characteristic of the power system and transitions the switching circuitry between the bidirectional mode and the unidirectional mode as a function of the characteristic thereby to prevent substantial reverse power flow through the rectifier.

Abstract: A soft start bridge rectifier circuit is described for controlling the operation of the bridge rectifier in order to ramp up the DC output upon connection with the AC input in order to limit in-rush current. Additionally, short-circuit/overload protection, temporary line loss protection and undervoltage checking circuitry is provided.

Abstract: In a complex power distribution network (e.g. CATV), a switching mode power supply at a node, automatically recovers from low input voltage conditions. When the input voltage to a switching power supply decreases to a critical level, the output voltage is no longer regulated and input current increases, and then the network becomes unstable. The network can enter a quasi-stable high current condition in which the output voltage remains unstable. In one specific embodiment, an automatic shut down circuit senses the unstable condition (or a voltage or current indicating the potential for instability) and latches the power supply into a shut down state. After a predetermined pause (that may depend on the input voltage), the power supply automatically restarts. Upon restarting, if the power supply is still unstable or potentially unstable, then the shut down circuit shuts the power supply down again and so forth.

Abstract: A first MOS transistor of a specific conductive type and a second MOS transistor of the specific conductive type are combined in an electrostatic circuit protection. In the first MOS transistor, a drain thereof is connected to an output terminal or an input terminal and a source thereof is connected to a first power terminal. The first MOS transistor is turned on/off by a signal received by a gate or ordinarily turned off by holding the gate at a specific potential. In the second MOS transistor of the specific conductive type, a drain thereof is connected to the output terminal or the input terminal and a source thereof is connected to a gate of the first MOS transistor. The second MOS transistor is ordinarily turned off by connecting a gate thereof to the first power terminal.

Abstract: A lossless snubber circuit is described for use with power converters, particularly asymmetric half-bridge converters. The snubber circuit provides a clamping circuit which has a clamping diode and a clamping capacitor connected across each of the rectifier diodes in the power converters output circuit. The clamping diode and clamping capacitor act to clamp the voltage across the rectifier diode and to recover the reverse recovery energy from the rectifier diode's turn-off. The reverse recovery energy is then transferred back to the input capacitors of the converter's input circuit through an energy recovery circuit. The energy recovery circuit includes a recovery switch which regulates the operation of the snubber circuit and a commutation transformer which provides the path from the snubber circuit to the input circuit. The snubber circuit allows the clamping voltage of the clamping capacitor to be adjusted to accommodate changes in the converter's conditions.

Abstract: A multi-range power supply unit with an automatic switchover between ranges for different power supply voltages is disclosed for use with devices such as circuit breakers or contact systems. The power supply unit preferably has only two input connections for an input voltage range of approximately 20V-230V. Between the two input connections there is a rectifier circuit with a voltage stabilizing element, such as a Z-diode or equivalent device, connected in parallel. Connected in series to the rectifier circuit is a current divider. The current divider includes a capacitance and a thermistor. The thermistor preferably has a positive temperature coefficient (PTC). The power supply unit can be used for a power supply with DC voltage and for a power supply with AC voltage.

Abstract: A circuit is disclosed comprising a switching rectification diode for rectifying a reverse transient voltage, a charging capacitor for charging an output voltage from the switching rectification diode thereon, and a discharging resistor connected in parallel to the charging capacitor, for discharging the voltage charged on the charging capacitor. With no limitation in frequency band, the circuit can effectively remove an instantaneous reverse transient voltage such as a reverse surge voltage or a reverse ringing voltage which results from abrupt variations in output voltages from preceding circuits. In addition, the circuit can stabilize operation of the associated device despite of heat so that individual components can be set to lower reverse withstand voltages.

Abstract: A power application circuit utilizes microelectromechanical (MEM) switches to reduce power loss in energy conversion equipment. The MEM switches can be integrated on a single substrate with a diode or semiconductor switch. The MEM switches can be included in a single circuit package with another semiconductor device and may include a control circuit which turns each MEM switch on or off. The MEM switch is controlled so that it is opened and closed only when a relatively low voltage drop occurs across the switch. The MEM switch can be utilized in AC to AC converters, DC to AC converters, AC to DC converters, matrix converters, motor controllers, resonant motor controllers, or other power application devices. The MEM switch can also be included in a single package with an IGBT which is optimized for low-switching losses. It can be included in a single package with a diode to reduce conduction loss in power diode bridges.

Abstract: For use with a post regulator for a power converter, the post regulator having a rectifier circuit and an output circuit, an energy recovery snubber, a method of operating the same and a power converter employing the snubber or the method. In one embodiment, the snubber includes: (1) a clamping diode and a clamping capacitor, series-coupled between the rectifier circuit and the output circuit, that cooperate to recover reverse recovery energy developed in the power converter to an output thereof and (2) a charge balancing circuit, coupled to the clamping capacitor, that maintains a charge balance of the clamping capacitor.

Abstract: A large inrush of electrical current flow occurs during a short interval after switch closure, when power is applied to a conventional electronic ballast commonly used for fluorescent lighting. This inrush current flows as the main filter capacitor in the ballast charges to its steady state value. For a lighting circuit that contains a multiplicity of ballasts, the combined magnitude of the inrush is potentially large enough to cause contact failure of the switching device due to arcing and contact welding. The invention features a circuit for limiting inrush current having a current-limiting resistor that is active for a brief interval during startup. The resistor is subsequently bypassed from the principal current path by a switching transistor. The transistor is controlled by electrical signals normally present in conventional electronic ballasts. The advantage of the inventive circuitry is the use of only two inexpensive components to accomplish inrush current protection.

Abstract: For use in a power system having a power train, a rectifier having an input and an output and a method of controlling the rectifier. The rectifier comprises: (1) switching circuitry coupled between the input and the output, the switching circuitry adapted to operate in selected one of (a) a bidirectional mode of operation and (b) an unidirectional mode of operation to rectify substantially alternating current at the input to produce substantially direct current at the output; and (2) control circuitry coupled to a control input of the switching circuitry, the control circuitry capable of sensing a characteristic of the power system and transitioning the switching circuitry between the bidirectional mode and the unidirectional mode as a function of the characteristic thereby to prevent substantial reverse power flow through the rectifier.

Abstract: For use with a buck-based converter having an isolation transformer, a snubber circuit and a method of damping a transient in the power rectifying diode due to its reverse recovery. In one embodiment, the snubber circuit includes: (1) a capacitor, coupled to a power rectifying diode in the buck-based converter, that receives energy from the power rectifying diode during a reverse recovery period thereof and (2) a flyback converter, coupled to the capacitor, that receives the energy from the capacitor and delivers the energy to a voltage source on the primary side of the isolation transformer.

Abstract: For use in a power converter having a rectifier coupled to an output thereof, a snubber circuit including an energy storage device coupled to the rectifier that moderates a voltage across the rectifier and a method of moderating the voltage. In one embodiment, the snubber circuit includes: (1) a first switch that regulates a voltage across the energy storage device, (2) an inductor, coupled to the first switch, that provides a discharge path for energy stored in the energy storage device when the first switch is conducting and (3) a second switch that recovers energy stored in the inductor to the output when the first switch is not conducting. The snubber circuit thereby reduces voltage stress across the rectifier during a current limit mode of operation.

Abstract: A boost converter module, a method of manufacturing the module and a power converter employing one or more of the same. In one embodiment, the boost converter module includes: (1) a power switch, (2) first and second snubber diodes series-coupled between the power switch and a converter output, (3) a snubber capacitor and a boost diode series-coupled across the second snubber diode and (4) an encapsulant substantially surrounding the power switch, the first and second snubber diodes, the snubber capacitor and the boost diode to join the power switch, the first and second snubber diodes, the snubber capacitor and the boost diode into an integrated package, the integrated package having: (4a) a control input coupled to the power switch, (4b) a power input coupled to the power switch, (4c) a snubber inductor input, coupled to a node between the snubber capacitor and the boost diode and (4d) a power output coupled to the converter output.

Abstract: A plant for transmitting electric power having an alternating voltage network with at least one phase and at least one VSC converter is provided. The converter has at least one phase leg with two current valves connected in series. Each phase leg is connected at a point between the two current valves to a respective phase of the alternating voltage network. The plant also comprises at least one additional phase leg in the converter more than the number of phases of the alternating voltage network and a means for disconnecting a phase leg from its respective phase and for connecting the additional phase leg at a point between its two current valves to the disconnected phase.

Abstract: An auxiliary power transistor which is switched in common with the primary power transistor, and which isolates the voltage-monitoring circuit when the primary power transistor is off. Thus the signal for sensing the secondary current is connected only when the power transistor is turned on, and high voltages in the sensing logic are avoided. This is particularly advantageous for systems where the turn-off times of the power transistor are sought to be synchronized with current zero-crossings. This current-zero-crossing technique may be used to detect zero-crossings of current on a secondary-side switch.

Abstract: An electronic power supply circuit (50) that includes a rectifying circuit (14), a boost converter (16), an in-rush current reduction circuit (52), and a bulk capacitor (18). The in-rush current reduction circuit (52) includes an in-rush current limiting resistor (54) and a bypass capacitor (56) that are connected in parallel with each other. An improved version of the in-rush current reduction circuit (52) includes a bypass diode (58) connected in parallel with the in-rush current limiting resistor (54) and bypass capacitor (56) which is oriented to provide a path for current flowing out of bulk capacitor (18). One particular application of the disclosed circuit is for use in an electronic ballast for fluorescent lamps.

Abstract: A voltage converter and a method for converting AC to DC. A MOSFET (42, 118) conveys current from a full wave rectifier to charge a capacitor (60) that supplies current to a load (64). In a first embodiment, two transistors (32, 34) are connected as a differential pair to control the voltage applied to the gate of the MOSFET, referenced to a zener voltage developed across zener diode (36) that is connected to the emitters of the two transistors. In a second embodiment, a single transistor controls the voltage applied to the gate of the MOSFET, relative to a zener voltage of a zener diode (132). The MOSFET charges the capacitor while the voltage applied to its gate from the rectified signal is greater than the voltage across the capacitor.

Abstract: A plug is diclosed that is adapted to be inserted into a standard electrical outlet and has a built-in integrated circuit for rectifying the alternating current received from the outlet and limiting the direct current produced. The plug is specifically suited for low-current, low-voltage applications such as supplying DC to a string of ornamental lights. The integrated circuit has a diode with a modified cathode that acts as a fuse as it is rectifying the alternating current. The cathode is formed of a plurality of electrically parallel conductors. Excessive current blows out at least some of these conductors in the same way a conventional fuse blows. Various embodiments add other current-limiting elements, elements for producing full wave or near full wave rectification, and for opening the circuit when they detect extraneous currents.

Abstract: For use in a power supply having a rectifying diode, a snubber circuit for, and method of moderating a reverse recovery current that flows from the rectifying diode as the rectifying diode transitions from a conducting state to a non-conducting state. The snubber circuit includes: (1) a saturable reactor, coupled in electrical series with the rectifying diode and providing a first conductive path for a first portion of the reverse recovery current from the rectifying diode and (2) a saturable reactor resetting circuit, coupled in electrical parallel with the saturable reactor and providing a second conductive path for a second portion of the reverse recovery current from the rectifying diode, the second conductive path reducing the reverse recovery current through the saturable reactor, thereby decreasing a thermal dissipation of the saturable reactor as the rectifying diode transitions from the conducting state to the non-conducting state.

Abstract: A direct current (dc) overvoltage, pre-regulation circuit regulates dc voltage supplied to a cable television line amplifier. The circuit provides overvoltage protection while permitting continuous operation of the line amplifier. The circuit opens the input to the downstream continuous voltage regulation circuit and cyclically charges a filter storage capacitor by periodic applications of the un-clipped voltage. The repeated switching regulates the dc voltage such that operation is sustained during periods of overvoltage that would normally shut down conventional circuits. No overall feedback is required to control the active device.

Abstract: In a rectifier bridge, a method and system for starting a DC-driven device without the occurrence of a current surge. The input of the rectifier bridge is connected to a three-phase source and a storage capacitor is connected across the output of the rectifier bridge. At least two of the three input terminals of the rectifier bridge are each connected in series to a respective AC capacitor. Each of the capacitors is connected in parallel with a respective controlled switch which functions to short-circuit the capcitors subsequent to the storage capacitor being charged.

Abstract: A lamp protection device includes a circuit to prevent a lamp from being switched on at full line voltage and which provides for the gradual heating of the filament to reduce the expansion rate of the filament. The circuit is connected to a switched alternating current power source and to an incandescent bulb. The circuit includes two silicon controlled rectifiers which are connected in reverse parallel configuration. One of the silicon controlled rectifiers being connected to a capacitor to prevent the full sinusoidal AC current from reaching the lamp until a time delay has expired after the lamp is turned on. A reference switch is connected to the other silicon controlled rectifier to permit the bulb to be turned on only when the AC voltage crosses zero.

Abstract: A novel switching mode power supply (SMPS), which is capable of substantially reducing the response time of the SMPS for generating a plurality of regulated DC output voltages from an AC input power, comprises a first rectifier for rectifying the AC input power to produce a rectified AC power signal within a predetermined range; a transforming device for generating a plurality of scaled-down AC power signals from the rectified AC power signal; a second rectifier for producing and providing a plurality of regulated DC output voltages from the plurality of scaled-down AC power signals to the plurality of loads through respective load lines connected thereto; and a unit for grounding the rectified AC power signal previously charged in the first rectifier if there occurs a disruption in the supply of the AC input power to the SMPS, to thereby promptly produce the plurality of regulated DC output voltages when the supply of the AC input power is resumed.

Abstract: A current-fed DC-to-DC converter (10) includes an input choke (20) which reduces current fluctuation in the converter (10). A power transformer (26), which is coupled to the input choke (20), transforms electrical energy at one voltage magnitude into electrical energy at another voltage magnitude. A first output rectifier (32) is coupled to the input choke (20). A second output rectifier (34, 36) is coupled to the power transformer (26). A first isolation diode (38) and a second isolation diode (40, 42) are coupled to the anodes of the first output rectifier (32) and the second output rectifier (34, 36), respectively. A transient voltage suppression element (12) is coupled to the first isolation diode (38) and the second isolation diode (40, 42).

Abstract: In a method and a circuit arrangement for driving semiconductor switches in a series circuit, in which a voltage limiting device is assigned to each semiconductor switch, the power losses of the voltage limiting devices are detected by a control equipment for equalizing the voltage distribution across the semiconductor switches. The control equipment generates modified control pulses for each semiconductor switch from a common control pulse on the basis of the detected power losses of the voltage limiting devices. By this means, the power loss of the voltage limiting devices is controlled to a minimum.

Abstract: A plug-in transformer power supply having magnetic and electronic circuits is optimized for output power while complying with UL Class 2 limits. In an embodiment, a 12 VDC unit capable of 21 W of output power is disclosed. In another embodiment, a 24 VDC unit capable of 33.6 W of output power is disclosed.

Abstract: A switching power supply apparatus rectifies an AC power input in a rectifier circuit, switches a rectified output and rectifies and smoothes the same in a switching circuit, and a desired DC voltage is derived. A current limiting circuit limits a current supplied to a smoothing capacitor of the rectifier circuit. A voltage detecting circuit detects a rectified output of the rectifier circuit. A current limiting control circuit controls the current limiting circuit in response to a detected voltage. The current limiting control circuit activates the current limiting circuit in a first preset period in which the detected voltage is equal to or lower than a preset level. Further, the current limiting control circuit activates the current limiting circuit for a second preset period after the detected voltage is first changed from a level equal to or higher than the preset level to a level lower than the preset level and then returned to the level equal to or higher than the preset level.

Abstract: A system of protection for an AC/DC hybrid electric power generation and distribution system having an AC portion comprising at least one source of AC power producing AC current coupled by first power feeders to a DC portion comprising at least one AC to DC converter producing DC current, the DC current being coupled by second power feeders to utilization equipment, comprises AC current sensors producing current sense signals proportional in magnitude to the AC current and DC current sensors producing current sense signals proportional in magnitude to the DC current. The AC current sensors define an entrance to a zone of protection, and the DC current sensors define an exit from the zone of protection. The AC and DC current sense signals are relationally compared to detect the presence of a differential current fault within the zone of protection.

Abstract: For overcurrent protection of a switch-mode power supply in a high power audio amplifier, an active feedback overload shut-down circuit acts though a control input of a PWM (pulse-width modulator) in the switch-mode power supply. In a multi-output switch-mode power supply, e.g. a dual-rectifier supply providing .+-.53 volts and .+-.100 volts suitable for a class H amplifier, instantaneous currents in each of the two rectifier circuits are monitored by primary windings of a current-sensing transformer, providing from its secondary winding a signal that is rectified and monitored by a comparator-timer for current overload at a predetermined threshold. The primary windings are made to have a particular turns ratio so as to proportion the protection sensitivity for each dc output voltage. Upon sensing overload from either rectifier circuit, the comparator-timer applies a shut-down signal to the PWM, shutting down the power supply safely for a predetermined time period, e.g. 17 seconds.

Abstract: Loss of excitation and control and subsequent damage to exciter windings in an excitation system for dynamoelectric machines wherein one or more rotating diodes fail in a shorted mode is prevented through the use of an RC circuit for detecting AC voltages in an exciter field winding for the purpose of directly operating a circuit breaker to remove excitation to the field windings and supply or to activate a timer for such purposes while temporarily shorting the AC current through the exciter field winding.

Abstract: An AC/DC converter is provided for connecting to conductors of a multi-phased alternating current generator or network, which is built redundantly for protection against a total loss and which loads the AC generator essentially without non-linear distortion and where several power factor correction circuits, arranged in parallel with one another, are provided. A number of rectifier circuits are included which are independent of each other and equal to the number of phases of the generator. Each rectifier circuit has six rectifier elements which are connected in pairs to terminals of the generator and, by the formation of bridges, are commonly connected to the output conductors of the rectifier circuits. Each rectifier circuit is connected to a one phase power correction circuit. At least one switch is provided for each rectifier circuit.

Abstract: A power device of improved input power-factor, reduced high frequency noise with rush current upon power source connection restrained, reduced switching loss and improved circuit efficiency is provided by an arrangement in which an output of a full-wave rectifying circuit is subjected to a high-frequency interruption through a switching means, an energy accumulated in an inductor connected to the switching means is applied through another switching means to a smoothing capacitor, and a current from the full-wave rectifying circuit so as to flow to the capacitor is interrupted by still another switching means.

Abstract: A short circuit current limiting reactor is disclosed having a series pass inductor wound on a core. A saturation control circuit is employed to control the magnetic saturation of the core. Under normal operating conditions, the core is in magnetic saturation thus making the reactance of the inductor negligible and allowing an AC current to flow freely through the inductor. Upon the occurrence of a short circuit fault, the saturation control circuit brings the core out of its magnetically saturated state thereby causing the reactance of the inductor to rise and limiting the amount of current flowing through the inductor.

Abstract: A bridge-type primary switching circuit (12) is represented by a pulsed voltage source (VSW). The primary switched waveform is transformed to secondary circuit (14) using a transformer (T1) with the required turns ratio N and a center-tapped secondary winding (16). Half-bridge rectifier (18) formed by diodes (DR1) and (DR2) rectifies the secondary waveform and feeds the waveform through a low-pass filter (LF) and (CF) to obtain the desired DC output voltage. The snubber circuit (20) is represented by switch-diode-capacitor combinations (SA-DS1-CS1) and (SB-DS2-CS2) across each rectifier (DR1) and (DR2). Capacitances (CS1) and (CS2) are selected large enough such that their voltages remain essentially constant during a switching cycle. The controlled switches (SA) and (SB) are turned ON with a specific delay after the primary voltage reaches a magnitude close to the input voltage in order to allow the rectifier diodes (DR1) and (DR2) to be commutated.

Abstract: A digital voltage protection circuit (138) and a phase monitor circuit (154, 160, 162, 168) disconnect AC-powered user equipment (22,182) from the AC power supply (141) whenever the AC power line voltage is outside a predetermined operating voltage window and when any two phases of the power supply (141) are separated by more than a predetermined phase angle. The user equipment (182) is automatically reconnected to the power supply (141) only after the power line voltage and phase remain continuously within operating range for a predetermined delay period. The voltage monitor (138) contains a digital comparator (18) that uses integrated circuit digital logic thresholds as reference voltages for setting upper and lower voltage window limits. The controller protects the user equipment from both over-voltage and under-voltage (brownout) conditions and from phase errors.

Abstract: A circuit configuration for actuating a safety relay (1) such as the main relay of an electronically controlled brake system of an automotive vehicle at least has two transistors (T1, T2) connected in series and a monitoring circuit (5) which will urge the transistors into the non-conductive state if there is a defect or trouble. The operativeness of the transistors (T1, T2) or of the monitoring circuit (5) will cause the safety relay (1) to be switched off.

Abstract: A power-supply unit having a rectifier circuit, switch, first and second voltage generation circuits, a control circuit, and a capacitor. The rectifier circuit is connected to an A.C. power source. The switch opens/closes an electric line which supplies a load circuit with electric power from the A.C. power source via the rectifier circuit. The first voltage generation circuit generates a first voltage based on an output voltage of the rectifier circuit. The first voltage is a non-zero voltage. The second voltage generation circuit generates a second voltage based on the output voltage, and is larger than the first voltage. The control circuit turns the switch on when the output voltage is in a range between the first voltage and the second voltage, and turns the switch off when the output voltage is outside the range.

Abstract: A method and apparatus for suppressing capacitive current in transformers is described. The winding of a transformer is constructed or modified into two substantially identical winding halves wired in a series aiding configuration. Two leads emanate from the center point of the winding, where the two halves are connected in series. This center point is at a constant potential throughout the switching cycle of the transformer. Suppression of the capacitive current in the input/output leads of the transformer is achieved by introducing common mode impedance into each lead and a corresponding center tap lead. The common mode impedance can be introduced in a variety of ways such as: running the pair of leads through a toroid, bead or sleeve of magnetic material; winding the leads on a magnetic toroid or rod; or using the magnetic core structure to introduce the impedance.