Abstract: A capacitor-charging series resonant mode, high voltage power supply (SRMPS) (10) includes a switching network (30) that alternately applies a positive and negative voltage to a series resonant circuit, comprising a resonant capacitor and inductor. The inductor may include the primary winding (14) of a power transformer (12). The switching action occurs at a fixed frequency above the audible range. This frequency is approximately the resonant frequency of the series resonant circuit. The switching action causes sine wave quantums of current of alternating phase to flow through the primary winding. Secondary windings (16) of the transformer are coupled through a suitable rectifying network (18) to charge a load capacitor C.sub.L to a high voltage. During a first mode of operation the load capacitor is charged at a maximum rate. During a second mode, the load capacitor is charged only as needed to maintain a desired charge thereon.

Abstract: High efficiency, post regulation of auxiliary outputs in multiple output-power supplied is provided by connecting a regulating switching device in parallel with a filter inductor connected in the current path from the rectifiers to the output terminal. For minimum output power for that auxiliary output, the switching device is held off at all times. When increased power is required, the switching device is turned on for a short period during each cycle of the inductor voltage. The switching system may be configured to conduct current from the output end of the inductor to the input end of the inductor or vice versa or either one selectively, in accordance with the particular regulation scheme chosen. Efficiency is maximized since current flows in the switching device for only a small portion of each cycle of the inductor voltage.

Abstract: In an inverter which converts a DC voltage input into AC voltage outputs of different phases, power transistors are arranged in an upper arm and a lower arm of the inverter. The temperatures of the power transistors in the upper arm are monitored by individual temperature sensors connected to overheat protection circuits. When an overcurrent flows through any one of the power transistors in the upper arm in a short-circuit situation, that power transistor is overheated. An alarm signal is initiated by the corresponding overheat protection circuit once the temperature of the power transistor is sensed to have exceeded a predetermined value. In response to this alarm signal, all of the power transistors are turned off and, thus, accorded protection.

Abstract: A power strip for use in high definition audio and video systems employing a device having a digital switching source is disclosed. The power strip includes a first receptacle for the digital source employing capacitors for shunting to ground high frequency products at the digital receptacle. The strip includes additional receptacles for non-digital devices, the additional receptacles being isolated from the digital receptacle by series inductances and also being isolated from ground.

Abstract: A network for connection between an AC power line and a DC power supply to isolate harmonic currents generated by the DC power supply from the AC power supply, the network employing three similar portions each connected between a repective conductor of the (three phase) AC power line and a respective conductor of the DC power supply. Each of the portions includes the series combination of three "reflectors" each having the parallel resonant combination of an inductor and a capacitor. Further, three series resonant inductor-capacitor combinations are employed each connected between a unique pair of the DC power supply conductors.

Abstract: A circuit for converting a DC voltage to a pulsating DC voltage useful as a power source for operating an AC machine. The circuit includes means for controlling the amplitude of the pulsating DC voltage as the load changes and means for controlling the duration of the pulses comprising the pulsating DC voltage.

Abstract: This invention relates to a push-pull inverter used, for example, as a driver for cold-cathod discharge tube, hot-cathode discharge tube, etc.According to this invention, respective control electrodes of a first switching element and a second switching element are interconnected by a capacitor so that a load current passes through this capacitor and thereby alternately activates the first and second switching element.With such arrangement, a boosting transformer requires no feedback coil and it is possible to eliminate a capacitor for resonance which has conventionally been connected in parallel to a primary coil of said boosting transformer.

Abstract: A universal phase-controlled reversible power converter having one transformer with multiple windings (i) couples a fixed d.c. voltage to an associated transformer winding through a fixed port having switches controlled for switching by fixed-phase signals, and (ii) couples any number of voltages having any waveform(s) whatsoever each to an associated transformer winding each through an associated variable port that has a filter with an inductor and controllable switches. Variable-phase switching control signals control the variable ports to produce any desired three-state demodulated waveform. A three-state demodulated waveform is filtered to present (i) a corresponding counter emf of any desired waveform to an input source or power, or (ii) any desired output waveform to a sink of power. Controllably producing the counter emf as a picture-of-the-line-input-voltage makes the load factor of the power converter, and all its loads, unity.

Abstract: A switching system for a step transformer having at least two adjacent taps and a pair of terminals shiftable between the taps has a pair of fixed contacts normally connected to the terminals, a vacuum interrupter connected between the terminals and displaceable between an open-circuit position and a closed-circuit position, a pair of movable contacts each engageable with a respective one of the fixed contacts and forming therewith a respective bypass switch, and a cam rotatable about a cam axis and having a contact face and an axially oppositely facing interrupter face each formed with a respective operating formation. A drive rotates the cam about its axis through steps of a half revolution. A respective cam follower engaged between each of the movable contacts and the contact-face formation opens and closes one of the bypass switches on rotation of the cam through a half revolution and thereafter opens and closes the other of the bypass switches on rotation of the cam through a succeeding half revolution.

Abstract: Megavolt voltage multipliers having an output impedance of less than 10 ohms and capable of operating at high pulse repetition frequencies, are switched with high performance saturable core inductors having multiple windings to provide voltage and current rise times of less than 50 nanoseconds. Pulse generation is actively initiated by a HV thyratron operating below 40 kilovolts and in the radar mode for long life.

Abstract: A direct-voltage flyback converter includes a primary winding of a transformer in series with the switching path of a controllable switch which is connected in turn to a control device (P). A first capacitor (C1) in series with a first diode (D1) is connected in parallel with the transformer primary winding (N1). A series circuit consisting of a first coil (L1), a second diode (D2) and the first capacitor (C 1) is connected in parallel with the switching path. In order to regulate the output voltage of the switched-mode direct-voltage flyback converter accurately and with low losses, and without the control device being activated from the secondary side, a sensing circuit (M) and a demagnetization circuit (A) are connected to the control device (P). A winding (N3) of the transformer (Tr) is connected in the sensing circuit (M) and a second coil (L2), coupled to the first coil (L1), is connected in the demagnetization circuit (a).

Abstract: A system is provided for controlling a PWM inverter having three main circuit arms in which free-wheel diodes are connected in parallel to positive and negative side switching elements. The inverter takes three phase alternating current from an intermediate portion of the arms on the basis of a voltage supply of a direct current and an ON and OFF operation of the switching elements. The control system includes a circuit for detecting a zero-crossing point of the three phase alternating current. A wave generating circuit generates a PWM wave at every main circuit arm, which changes the level thereof corresponding to ON and OFF operation of the switching elements and is inverted to each other in the positive and negative sides. An on-delay circuit delays a level change timing from ON to OFF of the PWM wave for a short circuit preventing duration.

Abstract: An improved electric power conversion system comprising a multi-phase bridge circuit composed of semiconductors such as thyristors and an associated firing circuit. It is so constructed that: if the AC input current Iac flowing in the bridge circuit is equal to or larger in value that the DC output current Idc flowing out of the bridge circuit, it will be decided than an inner defect or fault is caused, and possible expansion of inner defect will be prevented by disabling the firing circuit to extinguish the thyristors in the bridge circuit, and if the AC input current Iac is smaller than the DC output current Idc in value, the bridge is permitted to continue the operation of power conversion, thus eliminating unnecessary interruption which otherwise would be caused by exterior disturbances. Also, an improved electric power conversion system may be equipped with a device to prevent an adverse effect from being caused by abnormal rise of thyristors' temperature.

Abstract: The inverter circuitry requires minimal operating input power, is power factor correcting and may, if desired, include a dimming circuit. The circuitry further includes a runaway protection circuit which is activated upon sensing of a no load condition to place the inverter circuitry in a standby mode of operation.

Abstract: The disclosed power source apparatus includes a direct current (DC) source connected to the primary side of a transformer through a main switching element, a shunt circuit connected in parallel to the main switching element the shunt circuit being a serial circuit having an auxiliary switching element and a capacitor, and a control circuit connected to the main switching element so as to operate the main switching element at a duty ratio for generating a pulse-width-modulated output voltage at the secondary-side of the transformer depending on the duty ratio. The control circuit is also connected to the auxiliary switching element so as to turn off the auxiliary switching element when the main switching element is on or "closed" and to turn on the auxiliary switching element when the main switching element is off or "open". The auxiliary switching element and the capacitor in the shunt circuit are such that the shunt circuit has a small impedance at low switching frequencies of the main switching element.

Abstract: A power supply operable from power mains voltages generally within two voltage ranges according to which the power supply automatically switches between a full wave and a voltage doubler. Furthermore, the power supply provides automatic mode selection on a cycle-by-cycle basis, sensing the mains signal during an initial portion of the mains input cycle and causing the power supply to select a mode of operation during that cycle. Thus, the present invention provides rapid response to changing mains voltages. Moreover, the voltage doubler mode is inhibited during the initial power up period, providing a margin of safety when initially energized or when connected to rapidly changing mains voltages.

Abstract: A switchmode DC to AC converter, and particularly a master-slave half-bridge converter. The slave half-bridge power converter is controlled by a lower power self-oscillating half-bridge master converter. More particularly, the invention pertains to a high frequency ballast for gas discharge devices, especially, for high pressure sodium lamps, completed by a high voltage ignition apparatus.

Abstract: A gate pulse generator for a static var compensator (SVC) constituted by a thyristor switched capacitor (TSC) comprises voltage detectors for respectively detecting forward and reverse voltages applied to antiparallel-connected thyristors in the TSC. The antiparallel-connected thyristors comprise a plurality of series-connected forward thyristors and a plurality of series-connected reverse thyristors. The gate pulse generator monitors the forward and reverse voltages and determines whether a period in which both the forward and reverse voltages are zero continues for a predetermined period while reverse-phase sides of the antiparallel-connected thyristors are held in conduction periods, respectively. The gate pulse generator prolongs an active period of a forward conduction period signal by the predetermined period.

Abstract: To maintain a defined three-phase voltage system at the output terminals of a transformer device TE, for example, a transformer in a delta/wye connection where the primary-side neutral point is unconnected, even when an asymmetrical load is connected to it and to the secondary-side neutral point, single-phase transformers are used, whose primary windings are supplied with voltage by a pulse-width modulated, three-phase invertor in a bridge connection. Through the use of voltage regulators, the actual values of the secondary-side line voltages form the control voltages for each bridge-arm pair. The closed-loop control circuits of the three phase voltages are broken down in accordance with the structure of the transformer device by means of a break-down element. The setpoint values can be calibrated to a synchronizing voltage, and/or a current control for the conductor currents is superposed on the voltage regulators.

Abstract: A series resonant inverter is controlled to provide a substantially constant output voltage to a load. The control utilizes a combination of optimal control methods and phase modulation to enable time optimal responses to changes in state of the system. State determinants (including resonant capacitor voltage, resonant inductor current, source voltage, and output load voltage) are continuously monitored, and an optimal control signal is generated therefrom. When operating within the operable frequency range of the inverter's controllable switch means, frequency is varied to maintain proper operation. When operating at an extremity of the operable frequency range, phase modulation is employed.