Abstract: A tuning circuit in an RFID tag may be used to match antenna and integrated circuit (IC) impedances to maximize the efficiency of IC power extraction from an incident RF wave. The tuning circuit, which requires less power to operate than the IC, adjusts a variable impedance to improve the impedance matching between the IC and the tag antenna and thereby increase the IC power extraction efficiency. The IC may begin operating according to a protocol when it extracts sufficient power from the RF wave or when an optimal impedance matching and power transfer is achieved.

Abstract: A control system and method for a multi-phase motor substantially reduces or eliminates jitter resulting from. drive mismatch by replacing a conventional trapezoidal drive profile with a drive profile that causes the voltage applied across active phases of the motor to match the back-EMF across those phases. In an ideal motor, the back-EMF is substantially sinusoidal, and although the drive profile applied to each phase is not truly substantially sinusoidal, the drive voltage across the active phases is substantially sinusoidal. In a non-ideal motor, the back-EMF is not truly sinusoidal and the drive profiles applied to each phase are calculated to cause the drive voltage across the active phases to match the back-EMF across those phases.

Abstract: Systems, methods and computer program products for reducing or removing current spikes generated during a current recirculation period associated with phase switching in a spindle motor are described. In some implementations, the duty cycle of the drive signals applied to the windings of the spindle motor can be adjusted to reduce or eliminate the current surge resulting from current recirculation. In some implementations, the duty cycle of the drive signals during spin-up can be reduced based on a current limit, and the reduced duty cycle can then be used to drive the spindle motor taking into account of current surges in the supply current.

Abstract: A DC motor is provided. The DC motor prevents rush or overload of current in the DC motor during and/or after power input irregularities to the DC motor. A control circuit of the DC motor is configured to control current provided to the DC motor. When power irregularities in the power input to the DC motor are detected by the control circuit, the control circuit stops generating PWM (Pulse Width Modulated) signals and stops the current provided to the DC motor. After the stoppage of PWM signals, the control circuit can perform a soft-start of the PWM signals when the power irregularities are no longer detected. The soft starting of the PWM signals generates gradual increase in current to the DC motor, thus, preventing sudden rush of current that cause malfunction of the DC motor.

Abstract: The present invention relates to a motor controller of an air conditioner, including a converter for converting a commercial AC power into a DC power, an inverter including a plurality of switching elements, the inverter receiving the DC power, converting the DC power into an AC power through a switching operation and driving a three-phase motor, a gate driver for controlling the switching operation of the switching elements, and a plurality of voltage drop units connected between the converter and the gate driver, the voltage drop units dropping the DC power and supplying driving voltages for an operation of the switching elements. Accordingly, circuit elements within a controller can be protected.

Abstract: In a method for measuring motor speed and position by detecting the back-EMF generated during pole-pair interactions, fluctuations of a three-phase motor power supply that may affect back-EMF detection are reduced. One phase of the power supply is tristated for a certain interval preceding and during back-EMF detection. For a shorter interval during back-EMF detection, the voltage drop across the motor is reduced from the full power supply voltage. This preferably is accomplished either by pulling a first of the other two power supply phases low, while pulling a second of the other two power supply phases up to a regulated voltage below the power supply voltage, or by pulling the second of the other two phases up to the power supply voltage and pulling the first of the other two phases down to a regulated voltage above ground.

Abstract: A halogen lamp electronic transformer a power supply circuit, a voltage divider circuit, a control circuit, inductive coils, a push pull oscillator circuit, and a triggering and overload protection circuit. The push pull oscillator circuit consists of a plurality of push pull oscillator transistors, the bases of which are respectively connected to the positive ends of a plurality of inductive coils, with their emitters connected to the negative ends. As such, the positive electrical potential polarity reversal induced at the positive end of the plurality of inductive coils and the negative electrical potential reversal induced at the negative end of the inductive coils switch out and connect the plurality of push pull oscillator transistors to provide for the alternating continuity and cut off of the push pull transistors.

Abstract: For controlling the current in an inductive load, the gate current used to fire thyristors in a rectifier is controlled to reach zero at exactly the same time, within a given half-wave, as the current in the inductive load which receives the voltage from the rectifier, keeping gate voltage on as long as thyristor current is on. A discontinuous thyristor converter current signal is detected and used to generate an enable signal in conjunction with a thyristor gate voltage. The enable signal, in synchronism with a power supply line voltage, provides a pair of channeling signals which then, depending upon whether the field current is positive or negative, activate the gate voltages of the thyristors such that the gate voltages end exactly at that time, within a given half-wave, where the generator field current becomes discontinuous.

Abstract: A DC to AC power converter is disclosed which is connectable to a DC source, and including a first and second pair of switches which converts the DC source directly to AC by alternately switching between each of the first pair of switches at high frequency modulation, and between second pairs of switches alternately switching at each of the half cycles of the low frequency fundamental output voltage, for producing a positive pulse train and a negative pulse train. A transformer boosts the source voltage to the desired high voltage of the output of the converter circuit. A filter is connectable to an AC load and having a plurality of damping modes for extracting fundamental frequency from the output of the transformer, and having a control responsive to a signal for switching between damping modes. A sine wave oscillator generates a sine wave at the fundamental frequency. Feedback circuits maintain the AC output at the fundamental frequency.

Abstract: The invention relates to a method and to an arrangement for controlling the respective conduction times of two directionally opposed electrical devices (9,10) which are mutually connected in parallel and permit current to pass therethrough solely in one direction, and which also permit current (I.sub.2) to pass through the primary winding (2) of a transformer during a respective half-period of an A.C. voltage (U.sub.1) applied to the primary winding, this control being effected so that the magnetizing current through the transformer can be advantageously minimized and/or held beneath a given limit value when an asymmetric load (4,5) is applied to the secondary side (3) of the transformer. A magnetizing current in the primary winding corresponding to the load (5) of the secondary winding (3) is controled through the agency of different conduction times of the two directionally opposed devices (9,10).

Abstract: The invention relates to an inverter with a direct-voltage source and a chopper section, the chopper section having push-pull switching at a frequency f.sub.0. A parallel tuned circuit, the resonant frequency of which is 2f.sub.0 is provided between the direct-voltage source and the chopper section.

Abstract: An improved surge current limiting method and apparatus is provided for an inverter circuit. The inverter includes electronic switching devices serially connected between relatively positive and negative voltage buses and alternately conductive for providing alternating current paths through a load connected to a terminal intermediate the two switching devices. An inductor connected in series with the switching devices is provided with a permanent magnet core which is magnetically polarized in a direction such that current through the inductor attempts to reverse the magnetic polarity of the permanent magnet. The inductor is sized such that normal current through the inductor is not appreciably attenuated by the inductance. Under fault current conditions, the magnetic field generated by the higher currents through the inductor is opposed by the magnetic field of the permanent magnet so as to provide a substantial current limiting effect.

Abstract: There is disclosed a small-sized RF high-voltage power supply capable of stably supplying an RF high voltage to a load at the maximum power efficiency, even if the load has a nonlinear electrostatic capacity that varies with the applied voltage. The power supply has an RF step-up transformer equipped with a primary winding having a tap to which one end of a power capacitor is connected. An oscillating inductor, a thyristor, and the other end of the power capacitor are connected in series with each end of the primary winding in this order. Each thyristor conducts when a voltage is applied to it from the corresponding end of the primary winding. A diode is connected in antiparallel with each thyristor. The thyristors are alternately triggered to conducting state.

Abstract: A resonance inverter includes a DC power source, a resonance capacitor, an inductor, and a plurality of semiconductor switches. The resonance capacitor and inductor form a parallel resonant circuit. The inverter further includes control means for detecting a peak value of the voltage across the resonance capacitor, and for alternately conducting said semiconductor switches with a certain lead phase with respect to the peak point of the capacitor terminal voltage.

Abstract: A nondissipative current distribution circuit for a power source, such as magnetohydrodynamic generator, that delivers its output current through a first plurality of positive electrodes and a second plurality of negative electrodes (including plural positive and negative electrode pairs) and provides a predetermined current distribution among the electrodes, is described, and comprises a transformer including first and second windings, the second winding including means for connection to a load, the first winding having plural adjustable taps intermediate its ends, an inductor connected at one end to one end of the first transformer winding and at the other end to a plurality of capacitors connected respectively to each electrode, and a first plurality of silicon controlled rectifiers connected, respectively, between each positive electrode and a tap or the second end of the first transformer winding, and a second plurality of silicon controlled rectifiers connected, respectively, between each negative elect

Abstract: The invention relates to a high-voltage generator for supplying two different output voltages or output currents, particularly for X-ray tubes whose anode current deviates from the cathode current. Symmetrical output voltages can be obtained during operation of this device, despite asymmetrical loads to the anode and cathode, by using a resonant direct current/alternating current converter with a capacitor circuit which is discharged through two different primary windings. The discharge through one primary winding takes place with a preferably adjustable delay with respect to discharge through the other primary winding.

Abstract: In a protective circuit for the thyristors of an inverter circuit in a rail-bound vehicle, RC-R members are connected in parallel with the individual thyristors in order to prevent undue reverse voltages and a fuse is provided to cut off excess currents.In order to reduce the dimensions of the thyristors the series connection of a resistor and a decoupling blocking diode is connected in parallel with each thyristor. The respective center points of these components are connected, via a breakdown diode, with the control grid of the respective thyristor, so that the secondary voltage of the inverter circuit is reduced when there is a malfunction due to excess reverse voltage and the inverter circuit is disconnected from the rail-road mains.

Abstract: A dc-dc converter employs a parallel resonant circuit which is driven by square waves of current. By adjusting the frequency below the resonant point, the voltage on the resonant components can be stepped up. Switching losses in the inverter devices are low since the inverter feeds a lagging load allowing lossless snubber operation which allows the use of lossless snubbers.

Abstract: A parallel inverter circuit for converting DC voltage to a variable AC voltage. One terminal of the DC source is connected to an inductor and, in turn, through a pair of gate-controlled, main rectifiers (SCR's), to the opposite ends of a transformer primary winding. A center tap of the primary winding is connected to the other terminal of the DC source. A commutating capacitance is connected across the transformer primary winding and a means is provided for alternately gating the rectifiers. The level of the voltage wave generated across the primary winding of the transformer is varied by means of two gate-controlled, auxiliary rectifiers (SCR's) connected in parallel across the primary winding in reverse directions, and by a pair of additional windings coupled to the inductor referred to above and including one such winding in series with one of the auxiliary rectifiers and another winding in series with the other auxiliary rectifier.

Abstract: The DC to AC power inverter is of the class B, C, D or E type and includes a battery, at least one power SCR and associated capacitor circuitry, at least one input winding on a main transformer core and at least one output secondary winding on the transformer core. Such inverter requires a quiescent current to establish operating current for capacitor commutation charge and includes a feedback loading circuit for feeding current generated by the quiescent current back to the battery. The inverter also includes a self-detecting load demand circuit coupled to a line from said output winding for cyclically energizing the inverter, for sensing a minimum AC load and for holding said inverter in an energized state until less than a minimum AC load is sensed during an energizing cycle.

Abstract: A transistor is operated in the PWM mode such that a hlaf sine wave of current is delivered first to one-half of a distribution transformer and then the other as determined by steering thyristors operated at the fundamental sinusoidal frequency. Power to the transistor is supplied by a dc source such as a solar array and the power is converted such that a sinusoidal current is injected into a utility at near unity power factor.

Abstract: An inverter circuit, having a DC input and an AC output, has an input circuit portion which includes an isolating diode and an input filter including a choke and a polarized capacitor across the DC input. The DC chopper portion of the inverter circuitry may be either center-tapped--where half of the primary winding is in the circuit at any one time--or bridge-type--where all of the primary winding is in the circuit at any instant. In any event, the chopper portion of the inverter circuit uses SCR's and has 180 electrical degree commutation; with a commutation capacitor across the primary winding of the output transformer and a commutation choke in series with the SCR's. Feedback is provided by feedback diodes which are connected in counter-polarity to the polarized input capacity.

Abstract: A DC-to-AC inverter includes first and second resonant circuit loops each including a capacitor, a primary coil of an output circuit, a silicon control rectifier providing a current path in one direction around the loop, and a conventional diode providing a current path in the opposite direction around the loop. A DC source is connected to supply a charging current through charging chokes to the capacitors in the resonant circuit loops. The silicon control rectifiers are periodically and alternately rendered conductive each to start a cycle of oscillation in one resonant circuit loops, while the DC source provides current to charge the capacitor in the other resonant circuit loop. The charging chokes and primary coils are phased to supply voltages which add to the voltage of the DC source during the charging of the capacitors.

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.

Abstract: A full wave DC to AC inverter having two SCR inverter switches which alternately conduct to connect a DC source across one section or the other of a center tapped power transformer primary to establish an alternating current in the secondary. A commutating circuit includes a single capacitor which is charged during the conduction of the inverter switches and is alternately connected to the conducting inverter switch to turn it off. The commutating circuit employs a single transformer which has a primary winding connected in series with the primary winding of the power transformer and a secondary winding connected through an SCR and to the capacitor. A pair of SCR's, which are gated on by commutation trigger circuits, control the discharge of the capacitor to the appropriate SCR inverter switch.

Abstract: In a push-pull inverter (including a transformer) for changing direct current into alternating current, a circuit is disclosed for starting the inverter in which the first pulse of a rectangular pulse train applied to the transformer has a duration of one half that of the subsequent pulses. This aids in reducing the initial magnitude of the flux excursion in the transformer core.