Showing papers on "Inverter published in 1973"

Generalized Techniques of Harmonic Elimination and Voltage Control in Thyristor Inverters: Part I--Harmonic Elimination

Abstract: This paper considers the theoretical problem of eliminating harmonics in inverter-output waveforms. Generalized methods are developed for eliminating a fixed number of harmonics in the half-bridge and full-bridge inverter-output waveforms, and solutions are presented for eliminating up to five harmonics. Numerical techniques are applied to solve the nonlinear equations of the problem on the computer. The uneliminated higher order harmonics can be easily attenuated by using filter circuits in the output stage of the inverter. The results show the feasibility of obtaining practically sinusoidal output waveforms, which are highly desirable in most inverter applications.

System Oscillations from Negative Input Resistance at Power Input Port of Switching-Mode Regulator, Amplifier, DC/DC Converter, or DC/AC Inverter

Abstract: A switching regulator or a switching-mode amplifier, dc/dc converter, or dc/ac inverter can have a negative dynamic input resistance at the dc power input port. Frequently an LC decoupling filter is inserted in the dc power line between this equipment and the prime dc power source, to keep switching transients off the dc power buss. The negative input resistance of the equipment can exceed the positive output resistance of the LC filter and the power source. Then the system as a whole can oscillate. This oscillation can cause malfunction of the negative-resistance equipnent or of other types of equipment which may also be operated from the prime source. The conditions required for oscillation to take place are defined, and ways are shown to prevent the oscillation. The predicted oscillations have been observed experimentally.

System oscillations from negative input resistance at power input port of switching-mode regulator, amplifier, DC/DC converter, or DC/DC inverter

Abstract: A switching regulator or a switching-mode amplifier, dc/dc converter, or dc/ac inverter can have a negative dynamic input resistance at the dc power input port. Frequently an LC decoupling filter is inserted in the dc power line between this equipment and the prime dc power source, to keep switching transients off the dc power buss. The negative input resistance of the equipment can exceed the positive output resistance of the LC filter and the power source. Then the system as a whole can oscillate. This oscillation can cause malfunction of the negative-resistance equipnent or of other types of equipment which may also be operated from the prime source. The conditions required for oscillation to take place are defined, and ways are shown to prevent the oscillation. The predicted oscillations have been observed experimentally.

Inverter paralleling for harmonic reduction

Abstract: The invention describes a means for reducing the harmonic content of two or more paralleled polyphase inverters by displacing the phase relationship of the outputs of these inverters and connecting them through intervening reactors to a load circuit, which may be a motor or an output transformer, whose windings are phase displaced by the same amount as the inverter outputs. The load circuit includes a load winding with phase and auxiliary windings on one common magnetic circuit. The phase and auxiliary windings are conductively connected to each other and to two sets of terminals of the load winding so that the voltage on one terminal set is phase displaced from the voltage on the other terminal set by an angle corresponding to the phase displacement between the inverter outputs.

MOS power-on reset circuit

Abstract: An automatic power-on reset circuit adapted for use on complementary MOS integrated circuit semiconductor dies is provided. The circuit includes a voltage reference stage followed by an amplifier stage. A PN diode is coupled in series with a diode-connected MOSFET and a low current MOSFET device to provide a slight overdrive to the P-channel MOSFET of a CMOS inverter, which determines the initial output level thereof. As the voltage applied to the power supply conductor increases, the switching point of the amplifier-inverter stage varies until the output thereof assumes the opposite logic level. This transition of the output of the amplifier inverter stage is applied to wave shaping circuitry and an output circuit which reliably produces the desired reset signal.

Portable fluorescent lamp and inverter therefor

Abstract: A portable battery-operated fluorescent light with an inverter having a single transistor Class C oscillator and a gapped-core nonsaturating reactor transformer with a parallel capacitance in the secondary circuit to cause the secondary circuit to act as a resonant tank circuit for the oscillator. The lamp is capacitor-ballasted, and the batteries are rechargeable. A large capacitance is connected in parallel with the batteries to decrease effective battery impedance. The light has an automatic shutoff circuit using a zener diode to shut off the inverter when the batteries are discharged to the safe limit and a self-contained constant voltage current-taper charging circuit for the cells, with the same zener diode as a voltage reference. A jam-in lamp socket is shown which allow the lamp to be inserted straight into the socket without rotation, and a method for pulsing the filament at one end of the lamp to improve startup of aging lamps is disclosed.

MOS type semiconductor IC device

Abstract: A gate circuit having a plurality of gate inputs, for use in NAND, NOR or ROM (read only memory) circuits which are the basis of all of the logic circuits, comprising a load formed of a resistor or a MOS transistor, a driving stage including a plurality of MOS transistors for a plurality of input signals and having an output terminal, another MOS transistor having a different conductivity type from said driving MOS transistors, and a complementary MOS inverter receiving the output of this gate circuit as the input and supplying the output to the gate of said another MOS transistor of different conductivity type. This structure provides a reduction in the number of interconnections of the constituent elements while achieving low power consumption and high speed operation together with the ease of circuit design.

Circuit, such as cmos crystal oscillator, with reduced power consumption

Abstract: A complementary symmetry, metal oxide semiconductor device (COS/MOS) oscillator which includes a COS/MOS inverter and a regenerative feedback path from the output to the input terminal of the inverter. Power consumption is reduced, when current flow through the one device tends to increase, by applying regenerative feedback to an impedance in series with the other device to more quickly drive the other device to cut off, and vice versa. Degeneration across the impedances, when current flow therethrough tends to increase, also is employed to reduce power consumption.

Power source for fluorescent lamps and the like

Abstract: A power source for operating gas discharge lamps and other loads at high frequency from a high voltage supply, typically using 115 volts ac supply and providing a 20,000 hertz output. An inverter and lamp ballast circuit with fast starting circuitry and open circuit protection.

Radiation Failure Modes in CMOS Integrated Circuits

Abstract: The radiation sensitivity of commercial and laboratory CMOS processes has been investigated. Failure levels for CMOS circuits have been related to transistor threshold voltage shifts and typical inverter failure modes. CMOS inverter characteristics have been measured as a function of the ionizing radiation exposure for devices fabricated by 10 different manufacturers and representing a total of 15 different processes. By selecting certain processes, CMOS circuits can be obtained which will operate after exposure to an ionizing radiation dose greater than 106 rads (Si).

Frequency controlled inverter

Abstract: In a regulated dc to dc converter, a ferroresonant regulator is combined with a push-pull inverter on the same transformer, and a feedback circuit controls the frequency of the inverter in response to the rectified output of the regulator. A control winding on the inverter transformer is tightly coupled to the base drive windings that supply drive to the inverter transistors and loosely coupled to the primary winding that is driven by the transistors. The control winding is short circuited each half cycle at a time determined by the feedback circuit to reflect a low impedance into the base drive windings and a higher inductive impedance into the primary winding. The higher inductive impedance in combination with a capacitor in parallel with the primary winding forms a resonant circuit which insures efficient commutation of the inverter transistors and the control winding short circuiting device.

Extinguishing arrangement for the inverters of an electric motor

Abstract: An improved arrangement for extinguishing the inverter thyristors supplying current to an electric motor in which the output of the intermediate DC link supplying the inverter has placed across it two controlled rectifiers and a reversing choke along with a commutating capacitor connected in parallel with the reversing choke and one of the control rectifiers thereby permitting the motor current to be commutated even at operating speeds slightly above zero without the need for expensive circuitry.

Aspects of Multiple Infeed of HVDC Inverter Stations into a Common A.C. System

Abstract: The question of possible limits of HVDC power supplied to an a.c. system is discussed on a general basis. This limit will be of interest, if a.c. systems are to be reinforced without increasing their short circuit capacity. The two important aspects, i.e. power frequency and harmonic phenomena are discussed in view of investigations on single HVDC converters published earlier by other authors. The results are extended to multiple infeed. It is shown that in contradiction to the general opinion at present, the short circuit ratio presents no limit to the rating of a single converter station, that for multiple infeed each station can be dealt with separately with regard to its rating and that increasing the number of inverter stations connected to the same system does not increase the danger of harmonic instability.

Integrated circuit having a voltage hysteresis for use as a schmitt trigger

Abstract: This invention relates to a Schmitt-trigger circuit realized by MOS techniques employing insulated-gate field-effect transistors. To the common MOS inverter there is added a switched current source feeding a current to a series resistor thereby generating a voltage drop which is added to the inverter threshold voltage. The current source is switched on if the inverter transistor is blocked by the input signal.

Apparatus for the field-related regulation of asynchronous machines

Abstract: An asynchronous machine is supplied with impressed stator current by an inverter in a field-related manner as disclosed in copending application Serial No. 63,073. A definite commutation sequence is achieved by utilizing a sine-cosine oscillator for cyclically driving the control paths of the inverter. The frequency of the oscillator is limited to values of one sign. An additional angle correction control eliminates the commutation error angle.

The application of standardized control and interface circuits to three DC to DC power converters

Abstract: Standardized.control and interface circuits were applied to the three most commonly used dc to dc converters: the buck-boost converter, the seriesswitching buck regulator, and the pulse-modulated paral1el inverter. The two-loop ASDTIC regulation control concept was implemented by using a common Analog Control Signal Processor (ACSP) and a novel Digital Control Signal Processor (DCSP). This resulted in control circuit standardization and superior static and dynamic performance of the three dc to dc converters. Power components stress control, through active peak current limiting and recovery of switching losses, was applied to enhance reliability and converter efficiency.

Inverter ballast circuit for fluorescent lamp

Abstract: An oscillator including a single transistor is connected in circuit with the primary winding of a stepup transformer. The terminals of a fluorescent lamp are connected between the primary and secondary of the transformer. One filament of the lamp is connected in the base circuit of the transistor. The filament acts as a constant current device to limit the current flowing in the base circuit and thereby permit the inverter to operate over a wide range of input voltages.

Pulse transforming circuit arrangements using a clock pulse responsive delayed inverter means

Abstract: In a pulse transforming circuit arrangement for generating pulses responsive to the rise and/or fall of an input pulse signal, there is used a clock pulse responsive delayed inverting circuit which inverts the input signal at a point of time delayed from the level change of the input signal for a period corresponding to the width of the clock pulse, in accordance with the level of the clock pulse which changes in synchronization with the level change of the input signal. The clock pulse responsive delayed inverting circuit may be constituted by a clocked inverter. A NAND gate and/or a NOR gate generate pulses responding to the level variation of the input signal since the level of an output signal from the clocked inverter and the changed level of the input signal coincide with each other for a period corresponding to the width of the clock pulse.

Commutation control for inverter circuit

Abstract: An inverter circuit utilizing controlled rectifiers for changing direct current power to alternating current power is provided with control apparatus which includes means to sense variations in an operational parameter to provide compensation to insure that a current utilized to commutate or turn off a conducting rectifier is maintained substantially constant.

Commutation failure detection and control for scr inverters

Abstract: A direct current-to-alternating current inverter employing a silicon controlled rectifier (SCR) is described in which control means is provided to promptly and automatically restore inverter operation after a commutation failure. The control means includes means for sensing the instantaneous voltage across the SCR and comparing this voltage with a threshold voltage. Whenever the SCR voltage is lower than the threshold voltage, the gating pulses to the SCR and a series connected chopper of the inverter are inhibited. When the threshold voltage is exceeded, gating pulses are passed to the SCR and the chopper, thereby providing normal inverter operation.

ASDTIC control and standardized interface circuits applied to buck, parallel and buck-boost dc to dc power converters

Abstract: Versatile standardized pulse modulation nondissipatively regulated control signal processing circuits were applied to three most commonly used dc to dc power converter configurations: (1) the series switching buck-regulator, (2) the pulse modulated parallel inverter, and (3) the buck-boost converter. The unique control concept and the commonality of control functions for all switching regulators have resulted in improved static and dynamic performance and control circuit standardization. New power-circuit technology was also applied to enhance reliability and to achieve optimum weight and efficiency.

Inrush-current limiting device

Abstract: Apparatus, associated with an inverter circuit, for limiting inrush-current into a storage capacitor during an initial charging period, while minimizing the power dissipation of the limiting device during normal inverter operation. A resistive element provides a limiting device for the initial charging period of the storage capacitor. A silicon-controlled rectifier with associated apparatus, placed in a conducting state by the operation of the inverter circuit, provides an alternate low impedance path in parallel with the resistive element following the initial charging period.

Stabilizing system for an inverter-driven induction motor

Abstract: In a motor control system in which an induction motor is driven by an inverter and the motor tends to resonate, the resonant frequency of the motor and the extent of its damping are adjusted to desirable amounts by a local feedback circuit. An output signal of the local feedback circuit is algebraically added to a speed command voltage for the motor control system. A sum signal thus produced is connected to the input of the inverter to control the motor speed. The sum signal is also employed as one of two input signals to the local feedback circuit, the second input signal being proportional to the speed of the rotor of the motor and obtained from a sensor connected with the rotor shaft. The two input signals to the local feedback circuit are subtracted and their difference signal is processed through a lag circuit and a filter network to produce the output signal of the local feedback circuit. When the inverter and motor are thus stabilized by the local feedback circuit just described, it is much easier to stabilize a larger speed-control feedback loop in which the inverter and motor may be employed.

Commutatorless dc motor drive arrangement

Abstract: A commutatorless DC motor drive arrangement, in which an inverter is utilized to feed a synchronous AC motor, is provided with an all electrical speed control that eliminates the need for a motor shaft position sensor. The rate at which firing pulses are applied to the inverter, and hence the speed at which the synchronous motor is driven by the inverter output, is made dependent upon the magnitude of the applied DC voltage. Upon start-up of the drive arrangement, the applied DC voltage is made to increase in a linear fashion in order to provide gradual buildup of the motor speed. In order to ensure natural commutation of the inverter, an automatic trial-and-error method is utilized to determine that the inverter is started in the desired leading power factor mode of operation.

Constant power supply employing a variable frequency inverter

Abstract: A power supply useful for delivering substantially constant power to a plasma arc lamp or other load includes a variable frequency inverter having a substantially fixed pulse width. A constant power control circuit adjusts the inverter frequency to compensate for deviation of the output power away from a linear approximation of a constant power curve. In the control circuit, signals proportional to the output current and voltage are fed to a function generator which implements the linear approximation function. An error signal derived by comparing the function generator output with a reference voltage controls the frequency of an oscillator which in turn establishes the triggering rate of silicon controlled rectifiers (SCRs) in the inverter. The SCRs commutate off after a relatively constant time period, thus inverter output is proportional to the SCR triggering frequency. Cooperation of the control circuit and inverter maintains the supply output power at a constant level.

Analysis of High Frequency Inverter Circuit

Abstract: A bridge inverter circuit with tuned load is analyzed. A number of nomograms are presented and their use in the choice of circuit components is discussed.

Electronic converter with regulated output current and frequency

Abstract: A constant current converter utilizing a free running inverter employing current feedback. The inverter output current is sampled and used to control a switching regulator synchronized to the inverter, so that the supply voltage fed to the inverter holds its output current and consequently its output frequency substantially constant.

Basic Forced-Commutated Inverters and Their Characteristics

Abstract: In connection with the ever increasing applications of static inverters in the area of uninterruptable power systems and variable frequency ac motor drives, and the many forced-commutated inverter circuits that are proposed for these applications, an endeavor has been made to classify the impulse-commutated inverter circuits and to compare their characteristic features with each other. To attain this, the basic commutation circuits were considered generally, but yet varied enough to make some conclusions. Although there are but a few basic ways to insert a commutation impulse source in the forced-commutated inverter, many variations are possible, which make the design of inverters a difficult matter and very dependent on the desired specifications and the available components.

Clocked dynamic inverter

Abstract: A clock driven dynamic inverter produces high speed-low power signal inversion, with a high voltage output swing. Such operation is accomplished in one illustrative dynamic inverter embodiment with two specially phased clock driven switching MOSFETs, a dynamically driven load MOSFET, incorporating positive capacitive voltage feedback, and an input signal-responsive driver MOSFET.

Over-current latch-up protection apparatus for scr inverter circuits and the like

Abstract: This disclosure deals with over-current latch-up protection apparatus for SCR inverter circuits and the like, wherein an L-C network of frequency substantially lower than the inverter output frequency is interposed between the D. C. supply and the inverter to discharge through a short-circuiting inverter fault in such a way that the inverter''s supply voltage is momentarily reversed, enabling the recovery of the SCRs to their non-conductive state, without over-current damage.