Showing papers on "Inverter published in 1978"

Power supply for a high intensity discharge or fluorescent lamp

Abstract: This power supply for a high intensity gas discharge or fluorescent lamp exhibits near unity power factor with no third harmonic distortion, and facilitates highly efficient lamp operation with dimming capability. This is achieved by using an inverter to drive a resonant network that includes the lamp load. A feedback circuit adjusts the switching rate of the inverter to equal the resonant frequency of the network. Sinusoidal output voltage is achieved, together with voltage multiplication to a level sufficient to ignite the lamp and keep it lit during dimming. The inverter is driven by a switching regulator that is supplied with unfiltered, rectified ac power. A filter capacitor, connected across the regulator output, is sufficiently large so as to filter at the frequency of the rectified ac input. The regulator switching duty cycle is controlled in response to the average dc level across this filter capacitor. Lamp dimming is achieved either by adjusting the switching regulator dc output level or by varying the duty cycle of the inverter. The high power factor low distortion regulator concept may also be applied in other application where direct current power is derived from an ac line.

Femtojoule high speed planar GaAs E-JFET logic

Abstract: An integrated inverter stage operating in the gigabit range at a static power dissipation of 100 µW was built for future use in LSI logic circuits. Planar gallium arsenide technology was employed using selective ion-implanted enhancement mode junction field-effect transistors (E-JFET) having 3-µm gate lengths. A nine-stage ring oscillator served as a test vehicle to assess the speed-power product for digital applications. A theoretical analysis shows the transistor operates during the switching transient in the saturation regime, notwithstanding steady-state operation in the linear regime. When the transistor is switched off, the transient response is governed by the load resistance and the input capacitance of the subsequent stage. Means of reducing the switching time by increasing the supply voltage, nonlinear load devices, an output buffer stage, and reduction of gate length and width are described. Directly coupled E-JFET logic does not require level shifting, and, therefore, offers advantages over depletion-mode gallium arsenide MESFET logic by reducing the number of circuit elements per gate. Projected gallium arsenide E-JFET LSI logic circuits will surpass silicon-based bipolar logic with respect to both speed and power, and n-channel silicon MOS logic with respect to speed.

Inverter circuit for energizing and dimming gas discharge lamps

Abstract: An illumination control system for gas discharge lamps which can be dimmed is provided in which a central inverter produces a sinusoidal output voltage at about 23 kHz. The amplitude of the inverter output is adjustable to dim the lamps. A transmission line consisting of spaced wires having respective thick insulation sheaths distributes the high frequency power to remotely located assemblies of ballasts and lamps. The ballasts consist of passive linear components. A high power factor rectifier network is disclosed for providing a d-c input to the inverter from the 50/60 Hz mains. The inverter circuit is provided with novel controls for gradual start-up and turn-off and is protected against load fault currents and internal fault currents. Automatic and manual resets are provided for internal fault current and load fault current, respectively. The basic inverter circuit consists of two alternately conducting controllably conductive power switching devices. Each is in parallel with a respective oppositely poled diode. The input d-c power line is connected in series with the series-connected power switching devices. A single series tuned circuit is connected in series with an output circuit element and is connected across one of the power switching devices. The amplitude of the inverter output is controlled by adjusting the phase at which the power switching devices turn on. In another embodiment, a single power switching device is used for the inverter circuit.

System for energizing and dimming gas discharge lamps

Abstract: An illumination control system for gas discharge lamps which can be dimmed is provided in which a central inverter produces an output voltage at a high frequency which can be about 23 kHz. The amplitude of the inverter output is adjustable to dim the lamps. A transmission line consisting of spaced wires having respective thick insulation sheaths distributes the high frequency power to remotely located assemblies of ballasts and lamps. The ballasts consist of passive linear components. A high power factor rectifier network is disclosed for providing a d-c input to the inverter from the 50/60 Hz mains.

Module failure isolation circuit for paralleled inverters

Abstract: A module failure isolation circuit for paralleled inverters senses and averages the collector current of each inverter power transistor and compares the collector current of each power transistor with the average collector current of all power transistors to determine when the sensed collector current of a power transistor in any one inverter falls below a predetermined ratio of the average collector current The module associated with any transistor that fails to maintain a current level above the predetermined ratio of the average collector current is then shut off A separate circuit detects when there is no load, or a light load, to inhibit operation of the isolation circuit during no load or light load conditions

The Forced-Commutated Inverter as a Regenerative Rectifier

Abstract: The application of a three-phase 120°-gated forced commutated thyristor inverter as a regenerative rectification circuit is discussed. The circuit has the ability to accept or deliver dc current without change of nominal dc voltage magnitude or polarity and also has the capability to instantaneously change from ``motoring'' to ``generating'' and vice versa. An analysis of the circuit is undertaken to provide both the current waveforms and the regulation characteristic, which are compared with those of a conventional rectifier. Theoretical results are compared with those obtained from a laboratory working prototype.

DC-AC inverter

Abstract: In a DC-AC inverter having a switching circuit connected between DC input terminals and being controlled by pulses from an oscillation transformer to provide an AC output from which voltage and current feedbacks are applied to the transformer for maintaining oscillation thereof; the core of the oscillation transformer is formed, in part, of a core material having a large saturation magnetic flux density and, in part, of a core material having a high Curie temperature so as to provide the inverter with both a high efficiency and a stable oscillation frequency The DC-AC inverter is particularly suited to be included in a DC-DC converter constituted by applying the AC output of the inverter to a suitable rectifying and smoothing circuit

Electric washing machine

Abstract: PROBLEM TO BE SOLVED: To prevent generation of over-voltage or over-current so as to make safely processing possible, by deciding abnormality in a decision means in the case that an output of a voltage detection circuit is a prescribed value or more. SOLUTION: A control device 10 for an electric motor 7 is constituted by a DC power source 13 formed by connecting a rectifying smoothing circuit 12 to an AC power source 11, inverter 14 connected to an output of the rectifying smoothing circuit 12, voltage detection circuit 15 detecting output voltage of the rectifying smoothing circuit 12, and a control means 16 inputting an output of the voltage detection circuit 15. In the control means 16, a microcomputer as a decision means is provided, in the case that an output of the voltage detection circuit 15 is a prescribed value or more, abnormality is decided. In this way, the AC power source, in the case of high abnormal voltage, is quickly detected, generation of over-voltage or over-current is prevented in the rectifying smoothing circuit, inverter, etc., as a constitutional element, and safely processing is made possible.

Optimum PWM waveforms of a microprocessor controlled inverter

Abstract: Microprocessors eliminate the need to use PWM techniques which are easily implemented with hardware for inverter control. A search is thus made for an optimum technique regardless of complexity. Several techniques including a new one which minimizes distortion in an RL load are compared analytically and experimentally. A microprocessor-controlled inverter was built to implement these techniques. The new technique is suggested as a possible method of optimal adaptive inverter control.

MP-A1 Electron-beam fabricated GaAs FET inverter

Abstract: Direct writing electron-beam lithography has been utilized to fabricate GaAs FET inverters. The fabrication process used t o realize 0.5-pm FET integrated circuits on ion implanted channels is described. The bandwidth of the small-signal gi:in, the large-signal switching characteristics, and ring oscillator results are presented and compared with a computer simulation of the inverter.

Power conversion apparatus

Abstract: When a power conversion apparatus such as inverter or chopper comprises gate turn-off thyristors (GTO's), current limiting reactors are connected to cathodes of the GTO's and opposite ends of each of the reactors are connected to positive and negative terminals, respectively, of a gate power supply which supplies a turn-on current and a turn-off current to the respective GTO. With this arrangement, an energy stored in each of the reactors at the turn-off of the GTO is absorbed by the gate power supply.

Reversible variable frequency oscillator for smooth reversing of AC motor drives

Abstract: A variable speed ac motor drive such as a controlled current inverter drive with load angle control generates an inverter frequency command signal which at low speed has a large ripple component and a small dc component representing the desired frequency. A variable frequency oscillator is responsive only to the dc component and supplies timing pulses to a ring counter which generates thyristor gating signals in the forward and reverse phase sequence. Smooth reversing over a wide range of torque is realized, and multipulse operation is inherent at low speeds to modulate the inverter output and minimize cogging torque.

Variable-speed inverter-fed synchronous motor employing natural commutation

Abstract: A drive system is described which uses two conventional thyristor convertors to provide a d.c. link between a.c. mains and the varying-frequency voltages of a synchronous-machine stator, both convertors being naturally commutated by line voltages; the result is a variable-speed drive. The paper describes a detailed analysis of machine behaviour in the absence of saturation, but taking account of winding resistances. This analysis is used to investigate the effects of assumptions made in deriving a simple analysis, which takes account of magnetic saturation. The validity of the simple analysis is demonstrated by comparison with results obtained from tests on a practical drive system.

X-ray diagnostic generator comprising an inverter supplying the high voltage transformer

Abstract: The inverter utilizes an LC oscillatory circuit and a switching device for the alternate connection of this oscillating circuit to a d.c. voltage source. Adjustment circuitry is present for the adjustment of the capacitance and/or inductance of the LC oscillatory circuit. Through this circuitry, the inverter is adaptable to different load conditions.

High frequency lighting inverter with constant power ballast

Abstract: A lighting inverter for operating an electrical discharge lamp from a direct current power source. The inverter includes a resonant feedback inverter which converts the output of the d.c. power source to an alternating current output and regulates the a.c. inverter output voltage level by varying the frequency thereof. A ballast filter is coupled to the regulated output of the resonant feedback inverter and is formed by a series circuit of a ballast inductor and a ballast capacitor. Connected across the capacitor is the discharge lamp. Appropriate circuit parameters such as ballast inductance, ballast capacitance, inverter operating frequency, and the inverter resonant frequency are selected to maintain almost unity power factor at the input to the ballast filter.

Inverter starting system

Abstract: For starting a shut down inverter with the correct phase with a likewise shut down control unit, start control logic is provided, which is addressed by a signal imaging the phase of the monitored system voltage. The start control logic contains a memory for the phase of the system at the time of a disturbance. Upon a start command, the control unit is made to deliver firing pulses in such a manner that the output voltage of the inverter begins with the stored phase of the system at the instant of the disturbance. Preferably, the oscillator of the control unit is started with the stored phase.

Inverter power supply

Abstract: A high frequency inverter power supply including a transformer having a primary and a secondary with the secondary having a first winding and a plurality of second windings to suppy D.C. output voltages to a load. Switching transistors are used to switch a current from a D.C. input means through the primary to produce an alternating voltage across the first winding and the plurality of second windings. A rectifier coupled to the first winding of the secondary supplies power to a control means which generates first and second outputs for controlling the switching transistors, respectively. A start-up circuit provides temporary power to the control means until the rectifier supplies the power after which the start-up circuit is shut off. The control means (which is essentially a pulse width modulator) has an input thereto which is coupled to one of the output voltages for regulating these voltages. A photocoupler provides isolation between secondary and primary of the transformer.

Drive circuit for controlling current output rise and fall times

Abstract: In a drive circuit having output current passing through at least one bipolar transistor, the rise and fall times of the output current are predetermined by controlling the rate of current change in the master path of a current mirror amplifier which has a separate slave path connected to supply base current for each bipolar transistor. The drain-source channel of an MOS transistor is connected to selectively supply current flow through the master path of the current mirror amplifier in one embodiment of the rate control means and the gate of the MOS transistor is connected in parallel with a capacitor to the output of a CMOS inverter to which control signals are applied. Multiple outputs are driven from a single control input in another embodiment having a single master path and multiple slave paths incorporated into the current mirror amplifier with each slave path being connected to supply base current for a separate bipolar output transistor and being coupled to the master path through a separate transmission gate in a decoder which includes a transmission gate for each slave path.

Digital integrated circuit

Abstract: A digital integrated circuit is provided with a maximum number of input and output terminals assigned for a normal operation mode and the number of terminals required for a function test is minimized. The integrated circuit is additionally provided with at least one control terminal, the functions of at least a part of the input and output terminals being determined in response to the logical level at the control terminal. Terminal utilization efficiency is further enhanced if the control terminal is connected to an inverter which is nonresponsive to the normal logic mode voltage range but which is responsive to a voltage outside the normal logic mode voltage range.

Inverter for operating a gaseous discharge lamp

Abstract: A dc to ac inverter for operating a gaseous discharge lamp through pre-ignition, arc stabilization, warm-up and final run states is disclosed. The arrangement comprises a transformer and a pair of transistors connected for alternate conduction in a self-oscillating configuration in which turn off occurs at a predetermined flux level in each conduction period. The flux limit is used to preclude excess current drain during warm-up when the lamp resistance is at a minimum. A capacitor is provided, resonant at a harmonic of the inverter output waveform for producing the enhanced output voltage required for pre-ignition. The capacitor also helps to maintain a higher harmonic content during warm-up, enhancing the effective ballasting reactance during that period in relation to that during final run operation. A shift of the oscillating frequency of the inverter from pre-ignition to final run operation further enhances inverter operation.

Auxiliary commutation circuit for an inverter

Abstract: An auxiliary commutation circuit to compensate for transient type overload conditions of an inverter comprises a pair of oppositely charged capacitors controlled by separate switches, each operable at a particular time during the conduction cycle of the main thyristors to provide additional stored energy for commutation during overcurrent conditions. A current detector senses the load current and provides a signal to an auxiliary gate whenever the rate of change in the load current or its absolute magnitude exceeds a preselected value. In response to the overcurrent signal and a timing signal, the auxiliary gate renders the appropriate switch operative coupling the charged auxiliary capacitor in parallel with the primary commutation capacitor so that the combined electrical energy stored on both capacitors is available for commutation. After the commutation period the auxiliary gate maintains the switch in its open state for a sufficient period of time to allow the auxiliary capacitor to be recharged.

An inverter/controller subsystem optimized for photovoltaic applications

Abstract: Conversion of solar array dc power to ac power stimulated the specification, design, and simulation testing of an inverter/controller subsystem tailored to the photovoltaic power source characteristics. Optimization of the inverter/controller design is discussed as part of an overall photovoltaic power system designed for maximum energy extraction from the solar array. The special design requirements for the inverter/ controller include: a power system controller (PSC) to control continuously the solar array operating point at the maximum power level based on variable solar insolation and cell temperatures; and an inverter designed for high efficiency at rated load and low losses at light loadings to conserve energy.

A compatible NMOS, CMOS metal gate process

Abstract: An MOS LSI technology is presented, which allows the efficient fabrication of n-MOS and CMOS circuits on the same chip, a capability, which has become highly desirable in view of recent advances in circuit design, particularly analog-digital interfaces. The process starts from a p-type substrate. An n-well is formed by ion implantation. An additional implantation simultaneously sets the p-channel and n-channel threshold voltages as well as the field threshold above the substrate. The implanted field provides high density and simple processing. A third implantation step adjusts the threshold voltage of the n-channel depletion load transistor. Supply voltages up to 20 V are possible. Process modeling data are presented both by theoretical consideration and the measurement of actual profiles of the well and threshold dependence on energy, dose, and drive-in conditions. Distributions of the electrical parameters are rather narrow with standard deviations of thresholds <150 mV. Transconductance constants are typically 9 and 29 µA . V-2for p-and n-channel transistors, respectively. CMOS inverter gain is 250 for channel lengths of 10 and 25 µm, respectively.

Inverter drive circuit

Abstract: An inverter drive circuit is disclosed wherein the inverter is a pulse width modulated inverter. The inverter includes a regulator circuit to regulate the width of the pulses which control the conduction of first and second controllable semiconductors in the inverter. The regulator is controlled by the output of the inverter in a feedback arrangement with a current limit circuit as well as an instant current limit to limit the output. A turn-on circuit is utilized to act through a drive transformer to turn on the controllable semiconductors as required. A turn-off circuit acts on the drive transformer and turns off the turn-on signal. A set and reset circuit is provided using first and second drive transformers for first and second controllable semiconductors in the inverter. One transformer is set in order to provide the turn-on and then this transformer is energized in the opposite direction to saturation to obtain a reset. A decoupling diode is provided between the drive transformer and the control electrode of the semiconductor so that when the decoupling diode ceases conduction then reverse voltage developed by the drive transformer is not applied to the control electrode of the semiconductor. The foregoing abstract is merely a resume of one general application, is not a complete discussion of all principles of operation or applications, and is not to be construed as a limitation on the scope of the claimed subject matter.

Voltage comparator provided with capacitively cascade-connected inverting amplifiers

Abstract: A voltage comparator suitable for use in an analog-to-digital converter such as a successive-approximation converter, and provided with capacitively cascade-connected inverter stages to produce an output signal of a logic level 1 or 0 according to the relationship between the magnitudes of two analog input voltage signals to be compared. A first series circuit of an MOS switching transistor and resistive element is connected between the input and output of the respective inverters; a second series circuit of a MOS switching transistor and resistive element is connected between the input of each inverter and circuit ground. The MOS transistors of the first and second series circuits are simultaneously enabled or disabled by a clock pulse; and two input voltage signals to be compared are alternately applied to the first stage coupling capacitor.

Induction heating apparatus

Abstract: An induction heating apparatus includes an inverter circuit, a plurality of output coils for induction heating, a coil selection circuit for selectively connecting the output coils to the output terminal of the inverter circuit, and a control circuit for driving the coil selection circuit and inverter circuit so as to cyclically supply the output of the inverter to any selected one of the output coils for each predetermined time of a predetermined cycle. The induction heating apparatus further includes a plurality of output adjusting means for setting the output period of the respective output coils which is included in the predetermined cycle.

Control system of alternating current motors

Abstract: In a control system of an alternating current motor energized by a frequency converter including serially connected rectifier and inverter of the type wherein the speed of the motor is controlled by varying the phase of the output current of the inverter by varying the phase of a control signal of the inverter, there are provided a function generator which is supplied with a signal related to the motor torque for generating an analog phase angle signal related to the current phase angle, and a phase shifter responsive to the analog phase angle signal for shifting the phase of the control signal for the inverter.

MOS decoder logic circuit having reduced power consumption

Abstract: The present invention relates to a transistor circuit, and more specifically to a static decoder circuit made up of a series circuit of a NOR logic gate circuit consisting of a plurality of MISFET's for receiving address signals through the gates, an inverter circuit for receiving the output of the logic gate circuit through the gate, a first MISFET for receiving the output of the logic gate circuit through the gate, and a second MISFET for receiving the output of the inverter circuit through the gate, wherein said NOR logic gate circuit and inverter circuit are connected to a ground terminal via a first switching MISFET which receives the control signals through the gate, and said series circuit is connected to a power supply terminal via a second switching MISFET which receives the control signals through the gate. According to the circuit of the present invention, said first and second switching MISFET's are rendered off by said control signals during the standby periods, such that the current pass is completely interrupted between the power supply terminal and the ground terminal in the decoder circuit, and the output of the decoder circuit is rendered to acquire the ground level.

Current-Source Double DC-Side Forced Commutated Inverter

Abstract: DC-side commutated inverters are very attractive due to their simplicity and efficient use of the commutation circuit. A new current-source commutated inverter of this type equally applicable to both single and multiphase bridge configurations is considered. Simultaneous turn-off of all bridge thyristors allows ample possibilities for programming the commutation sequence. The behavior of a threephase bridge is analized, and the optimum values of the commutation components are obtained. Guidelines for analysis under any commutation condition, as well as general programming rules and suggestions for snubber design are given. Results obtained in a 8-kVA variable speed drive prototype are shown and discussed.

Current controlled inverter

Abstract: An inverter circuit changes direct current power into alternating current power at a desired voltage and frequency across the load and feeds power back into the direct current source by controlling the duration and spacing of controlled signals for a lightweight transformer in accordance with the direct current input voltage and a predetermined varying output voltage.