Showing papers on "Inverter published in 1969"

Fast response stepped-wave switching power converter circuit

Abstract: To obtain fast response to a cyclical AC or variable DC input reference signal by a stepped-wave power converter circuit comprising a plurality of equal or unequal inverter modules connected in series or parallel so that the module output voltages add algebraically, the composite instantaneous output stepped-wave voltage is compared with the instantaneous voltage values of the limits of a control band placed about the reference signal. One or more inverter modules are switched to produce a step change whenever the composite output voltage is outside the control band limits. An application is a fast response switching power amplifier for driving sonar transducers.

Analysis and Simplified Representations of a Rectifier-Inverter Induction Motor Drive

Abstract: Simplified representations of a rectifier-inverter induction motor drive system are established and verified by comparing the results obtained from a computer study using these representations to those obtained using a detailed simulation of the system. It is shown that when all harmonic components are neglected the static drive system may be conveniently represented in the synchronously rotating reference frame. The computer simulation resulting from this type of representation can be readily implemented, and in many cases it will predict the system performance with sufficient accuracy. Also, in the analysis leading to these simplified representations, the operation of the inverter is analytically expressed in the synchronously rotating reference frame with the harmonic components due to the switching in the inverter included. These equations of transformation may be used to advantage in describing the interaction between the filter and the induction motor.

General Analysis of Three-Phase Inverters

Abstract: A method of analysis for three-phase inverters is described. The method is based on Park vectors [1], [2] and predicts the waveforms of inverter quantities under various load conditions. The procedure discussed can be used to determine the commutation sequence of a pulsewidth modulated inverter. The current distribution of the inverter can be obtained from the current vector. The vectors of the inverter voltage and currents are determined for passive R-L and R-C loads. Oscillograms of the current vectors are shown for different loads.

Inverter system with automatic ridethrough

Abstract: For enabling a variable frequency electric power inverter to ride through a temporary loss or reduction of input power, means is provided for sensing an excursion of DC bus voltage beyond a predetermined normal magnitude range and for deriving first and second signals respectively proportional to the magnitude of the excursion and to its integral, and the frequency of the inverter is varied according to the difference between a given signal and the sum of said first and second signals.

Dc to dc converter circuit with load voltage regulation utilizing a controlled simulated saturating core

Abstract: An inverter circuit driving a ferroresonant regulator utilizes a feedback controlled switching frequency arrangement to regulate its output voltage with respect to both line and load conditions A deviation in the output voltage alters the switching frequency of the inverter by altering the simulated saturation of a switching control transformer core included in the inverter circuit The output voltage of the ferroresonant regulator, which is proportional to the inverter frequency, is adjusted to some regulated value Saturation of the inverter transformer is simulated by controlling the volt-time area of the output voltage waveform of the inverter transformer

A Digital Model for Three-Phase Induction Machines

Abstract: A digital model for a three-phase induction machine is developed, which is particularly adapted for studying its dynamic performance when fed from an inverter. Conventionally, the induction motor is analyzed in terms of its d-q variables, while the operation of the inverter generally needs continuous monitoring of the state of its phase quantities. Thus in a study of the composite inverter-induction-machine system, one is faced with the problem of matching the two sets of variables. The proposed model overcomes this problem by describing the machine behavior directly in terms of the stator phase variables, at the same time retaining a computational simplicity comparable to that of the d-q equations. Furthermore, it is shown that the machine equations, expressed in terms of the stator terminal variables, can conveniently handle the various terminal conditions, like open phases, that may arise when the machine is fed from an inverter. Detailed equations in a form suitable for digital solution are also presented for possible terminal constraints of this nature, with or without the machine neutral connected to supply.

Analysis and Simplified Representations of Rectifier - Inverter Reluctance-Synchronous Motor Drives

Abstract: Methods of analyzing six-step and pulse-width- modulated (PWM) types of rectifier-inverter reluctance-synchronous motor drive systems are set forth. In this development the harmonic components due to the switching of the rectifier are neglected, and the operation of the inverter is expressed in a reference frame rotating in synchronism with the fundamental frequency of the inverter output voltages. In the case of the PWM inverter, the Fourier series expansion of a pulse train is used to express the operation of this type of inverter in the synchronously rotating reference frame. Simplified representations are obtained by neglecting the harmonics due to the inverter switching. These simplified representations are verified by comparing the results obtained from a computer study using these representations to those obtained using a detailed simulation of the system. The analysis set forth and the simplified representations that are developed can be used to determine small-displacement system stability, as well as provide a simple and direct technique of predicting the dynamic and steadystate performance of these involved systems. Moreover, the equations established for the PWM inverter can also be used in conjunction with an induction motor drive.

Threshold logic for integrated full adder and the like

Abstract: Threshold logic functions are carried out by the use of an insulated-gate field effect transistor (IGFET) connected as a sampler transistor in series with a not-clock input and a parallel combination of several data input IGFET''s. The sampler transistor and the data input transistor combination form a voltage divider whose center tap is connected to the input of an IGFET inverter operated from a clock input. By using data input IGFET''s with different ''''on'''' resistances, the data inputs can be selectively weighted, and a full adder circuit can be constructed with only 15 components, all of which are IGFET''s, and all of which can be manufactured on a single chip.

Optimum Design of an Input-Commutated Inverter for AC Motor Control

Abstract: In any forced commutated inverter scheme, a certain amount of energy is "trapped" at the end of the commutation interval. It is desirable to minimize this level of trapped energy for best circuit component utilization. An input commutation circuit, suitable for single or three-phase inverter circuits, is introduced as a model. A mathematical analysis of the circuit yields expressions for circuit component values in terms of the load impedance at the instant of commutation. Optimizing procedures produce direct expressions for the components to yield the most efficient operation and minimum trapped energy.

High-frequency lamp circuit for copying apparatus

Abstract: A high-frequency power supply for the light source of a xerographic-type copying machine in which power from a normal 5060-cycle AC input is rectified and regulated to provide a constant current or constant voltage DC input to a high-frequency oscillator-inverter providing output power at a frequency in the order of 20,000 c.p.s. or above to a light source comprising one or more gaseous-type lamps. In a modified circuit the DC input to the inverter is regulated by a solid-state chopper controlled by a magnetic amplifier pulsed by a free-running multivibrator and modulated by the input current.

A brushless dc motor system combined with a thyristor bridge inverter

Abstract: A polyphase thyristor bridge inverter wherein, to energize the polyphase armature winding of an electric motor, the thyristor bridge is subjected to either natural or forced commutation, the latter being effected more reliably than the former, the thyristor is safely operated under a rated load or a heavier load required, for example, in starting the motor, and the forced commutation is preferably used for such heavier load to eliminate the wasteful motion of the inverter.

Mos bipolar push-pull output buffer

Abstract: An output buffer for an MOS integrated logic circuit which utilizes an output stage comprised of a bipolar transistor and an MOS transistor connected in push-pull configuration is described. The output stage is operated by an MOS control circuit which utilizes an inverter stage with an improved capacitive bootstrap switching network to reduce the magnitude of the gate supply voltage required for positive switching. The circuit is characterized by very low input capacitance, and very low output impedance and thus high capacitive drive capability. A unique connection to ground internally of the integrated circuit is also described which comprises a diffusion made at the same time as the emitter diffusion of the bipolar transistor to provide ohmic contact between an overlying conductor and the substrate which then provides the return path to ground.

Motor control system with volts/hertz regulation

Abstract: An AC motor is energized by the output voltage of an inverter which in turn receives a DC input voltage from a DC-to-DC converter. A combined oscillator-regulator circuit includes a first potentiometer for adjusting the desired volts/hertz ratio of the inverter output voltage, and a second potentiometer for regulating motor speed. The combined oscillator-regulator receives an output signal from the inverter for comparison against the desired volts/hertz ratio signal, and provides two control signals. The first control signal regulates the operation of the DC-to-DC converter, and the second control signal regulates the frequency of the inverter output voltage.

Motor current control circuit utilizing real current component

Abstract: A control circuit obtains a signal proportional to current supplied to an induction motor from a variable-frequency inverter. A phase-sensitive detector discriminates between the real and reactive components of the motor current and the real component is fed back to control the current to the motor, preferably in a current limit circuit which limits the torque output of the motor. 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.

Low cost variable input voltage inverter with reliable commutation

Abstract: A low cost, solid-state variable input voltage inverter recharges each commutating capacitor through an impedance and a controllable semiconductor switch, preferably a resistor and a transistor in series with a commutating capacitor, to the value of a source of fixed or predetermined voltage to assure reliable commutation over the entire range of input voltage control. The inverter is constructed in single and multiphase versions and is especially suited for industrial applications such as a wide range variable speed AC motor drive.

Speed compensation motor circuit utilizing real current component

Abstract: An induction motor energization circuit id disclosed with energization from a variable frequency device such as an inverter. The load current to the induction motor has a considerable lagging power factor and a phase-sensitive detector detects only the in-phase or 180* out-of-phase component of this load current and applies it as a control to regulate the variable frequency device. The typical induction motor action is one where the speed droops because the slip increases as the torque increases and may be 2 to 3 percent of base speed. A signal such as the in-phase component of load current which is virtually proportional to torque is used in this invention to correct the frequency output of the inverter by 2 or 3 percent, therefore virtually eliminating the speed or slip error. By the present invention the use of only the real component of the motor load current as a feedback signal results in a substantially constant speed of the motor. 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.

Recovery system for short circuits through switching devices in power circuits

Abstract: When a short circuit or shoot-through occurs in a power circuit having two thyristors in series with commutating circuit inductors, a shunt capacitor isolated from the DC power supply by an impedance automatically resonates with the inductors to turn off both thyristors. A second automatic recovery system for repeated short circuits that occur before the capacitor has recharged operates to temporarily disable the power supply. In a high-voltage inverter the impedance is a resistor functioning to dampen voltage overshoots and to implement a relay or solid state second recovery system.

High frequency battery charger employing an inverter

Abstract: A charger designed to be within a specified weight limitation employs a method and circuit for rapid-charging which circuit employs an inverter for changing a direct current voltage to an alternating-current voltage having a substantially square wave form and a relatively high frequency in the order of 10,000 Hertz, and a rectifying circuit connected to the output of the inverter, for changing the high frequency alternating-current voltage to direct-current voltage for application to the battery to be charged. At least one unilateral impedance element is in the current path through the rectifying circuit with the element briefly providing a discharge path for the battery at the end of each period of forward conduction through the element.

Electronic inverter having precharging control affording high frequency switching at low output

Abstract: A single or plural phase solid state inverter having a half bridge for each phase and each half bridge including a pair of power semiconductor controlled rectifiers for switching, inductance-capacitance circuits for commutation of the power SCR''s, a separate and electrically isolated precharging supply for each phase, and a pair of voltage level detectors of the solid state type that allow use of the commutating energy in one part of the half bridge for charging the commutating capacitor to the required voltage level in the other part of the half bridge, above which the level detector becomes operative to allow feedback of the remaining energy to the supply, thereby to afford relatively high frequency switching in the inverter at low output voltages in an efficient manner.

Method of Multiple Reference Frames Applied to the Analysis of a Rectifier - Inverter Induction Motor Drive

Abstract: The method of multiple reference frames and the equations of transformation of the inverter are employed to establish a method of calculating the inverter current in a rectifier - inverter drive system. Since the method of multiple reference frames does not use phasors or complex impedances, the calculation of the inverter current is simple and direct. Also presented is a method of approximating the 6th harmonic variation in the capacitor voltage of the filter, connected between the rectifier and the inverter. This method permits a simplified means of rapidly obtaining a first- order approximation of the variation in the capacitor voltage. The analysis establishes a straightforward method of calculating variables in a rectifier - inverter drive system, which are difficult to determine by conventional methods of analysis.

Regulated inverter using synchronized leading edge pulse width modulation

Abstract: A regulated inverter circuit wherein leading edge pulse width modulation is obtained by employing a modulator control network synchronized with the sinusoidal feedback bias which delays the application of this bias for an interval determined by load voltage variations. Deleting the leading edge of the sinusoidal driving waveform allows the inverter transistors to be efficiently biased from cutoff to saturation and at the same time eliminates the adverse effects of stored charge when the transistors are driven from saturation to cutoff.

Mosfet momentary switch circuit

Abstract: A metal oxide semiconductor field effect transistor (MOSFET) circuit of a type that can be constructed on a single semiconductor substrate which accepts a signal from a manually operated momentary switch and provides a DC output signal at one of two possible voltage levels The circuit includes a trigger flip-flop which provides the DC output signal The circuit also includes a NOR gate, an RS flip-flop and an inverter interconnected in a manner to prevent the spurious signals caused by switch contact bounce or line noise from giving an incorrect indication at the output of the circuit

Fluorescent lamp apparatus including inverter circuit and reflector

Abstract: An electronic inverter circuit particularly suitable for energizing fluorescent lamps from a direct current power supply wherein transistors are employed as switches in a self-excited oscillator circuit. The circuitry includes a transformer core alternately saturable at a high frequency under the control of the transistor switches, the transformer including a feedback winding controlling operation of the transistors. A transformer secondary winding supplies a high voltage output to the fluorescent lamp, and the high voltage output includes a conductor disposed adjacent the lamp to reduce the voltage required to initiate an arc therein.

Ignition device for internal combustion engine

Abstract: A low DC voltage boosted by an inverter and a rectifier charges a capacitor a charge on which is, in turn, discharged into an ignition coil under control of a thyristor Upon starting the engine, the DC voltage is applied to an intermediate terminal of a primary transformer winding in the inverter Diodes are connected in a circuit for gating the thyristor to prevent the circuit from partly short-circuiting the primary winding through the intermediate terminal

Transistor inverter circuit

Abstract: A transistor circuit capable of receiving a high voltage, low frequency supply and changing it to a low voltage high frequency supply.

Mos circuit with bipolar emitter-follower output

Abstract: An inverter for a metal-insulator-semiconductor integrated circuit which utilizes an MOS inverter stage followed by a bipolar emitter-follower stage is disclosed. The inverter stage may have multiple inputs to form a gate. The emitter-follower stage employs a bipolar transistor with an MOS transistor as the load impedance. The size of the output MOS transistor can be changed to provide optimum drive characteristics without redesigning the remainder of the integrated circuit. The emitterfollower output stage provides a very low output impedance, and therefore has the capability to drive higher capacitive loads.

Inverter for generating single or multiphase current

Abstract: An inverter for generating single or multiphase current, comprising series networks equal to the number of phases, such networks being connected to a DC source or sources. Each said series network includes two capacitors in series connection with the common junction between the two capacitors as one load terminal which is connectable to its respective phase load. At least one electronic commutator is provided for each series network, said commutator being connected to a respective second load terminal and being switched alternately between the ends of terminals of the series network. Means are provided for triggering the commutator in sequence with and at the proper phase of the frequency of the alternating current to be generated. The inverter provides a power source for inductive current consuming appliances, particularly induction motors.

Application of Inverter Drives

Abstract: This paper outlines experience gained over the past six years in the use of adjustable-frequency power inverters for industrial applications. Expected performance factors such as frequency and voltage accuracy, reliability, and flexibility are discussed. The characteristics important for proper performance are noted and comparisons with rotating type drives are made in the areas of installation, performance, and maintenance. In conclusion, future trends for the adjustable-frequency inverter are discussed.

A-c voltage regulator

Abstract: 1,179,616. Stand-by supply arrangements. BORG-WARNER CORP. 14 Dec., 1967 [27 Dec., 1966], No. 56935/67. Heading H2H. [Also in Division G3] A no-break standby supply arrangement for a load 88, which is normally energized over an inductor 87 and a line 11 from a primary A.C. line 86, comprises an inverter 10 which is connected to the load 88 by way of a voltage regulating system 23, 24, 26 (see Division G3); the inverter 10 derives its input from a charger 90 which is connected to the A.C. line 86 and which also charges a battery 11, a synchronizing unit 92 being provided so that the inverter output voltage is in phase with the output voltage on line 11. Thus, if the primary supply fails the battery 91 supplies the load over the inverter 10; if the voltage on line 11 should fall, the inverter commences to supply energy to the load and aids the primary supply; in addition, if the load voltage becomes too high the inverter operates regeneratively to charge the battery 91 and aids the charger 90. The inductor 87 isolates the load 88 from the effects of a short-circuit on the line 86.