Abstract: In a direct AC to AC converter system the normal rectifier assistance functions are phase modulated by a 30.degree. lag and by a 30.degree. lead, and switching between lagging and leading function is effected at a high frequency according to a duty cycle: ##EQU1## and where .theta. is the electrical angle of the AC power supply, thereby insuring a sinusoidal input current in the system.

Abstract: A control processor in a robotic system treats optically sensed locations along the seam path ahead of the tool, which are classified in relation to elapsed distances and identified in 3-D coordinates and 3-axes tool orientation, to apply in real time and under feedforward a control signal representing the error between anticipated tool position and anticipated sensed location on the path. In the process, the anticipated sensed location is obtained by interpolation between acutally sensed locations. A taught path is recovered from the robot. The control processor operation is also based on elapsed distances and related to actual tool position provided by the robot.

Abstract: In order to maintain low telephone interference (IT factor) during its normal operation and to establish rapid-post-fault voltage support to preserve the integrity of electric power transmission lines in the presence of degraded system impedance and harmonic instability, amplitude detection in a transmission voltage regulator (static VAR generator, SVG) is provided based on real time conventional, or fast, Fourier analysis, data samples being used to establish the fundamental voltage amplitude and collected during a specific, frequency tracking sliding window that precedes the amplitude reading by one line voltage cycle of the transmission line. The number of samples in the window is an integer multiple of the line frequency and, in the case of conventional analysis, the pulse number of the switching power circuit is used in the SVG. The amplitude value is updated after each sampling by shifting (sliding) the one cycle sample data base in a first in - first out manner.

Abstract: In an AC motor drive, a voltage-source inverter is provided in the DC-link thereof with a GTO switching arrangement which upon braking allows matching the voltage, current domains for the forward power and regeneration modes, the GTO devices being interrupted with a duty cycle selected in response to the voltage difference between the inverter DC input voltage and a constant reference voltage.

Abstract: In a microcomputer-based multi-function thyristor-controlled AC induction motor drive, the microcomputer effectuates the several control functions of the motor drive during respective time intervals corresponding to the sequence of firing of the thyristors, and upon each new time interval, depending upon the required delay angle, firing is effected as a function of a residual angle in terms of a multiple of said time intervals, and the firing sequence is shifted by an amount of time intervals in relation to the integer number of such time intervals within such delay angle. As a result, firing of the thyristor is performed by the microcomputer without impeding control function determination and with improved response to change in the delay angle.

Abstract: In a current-source GTO converter, protection against a DC fault or a commutation fault condition is provided by immediately interrupting the conduction of a GTO device which is ON and by turning ON another GTO device to allow fault current to bypass the bridge or safely pass through the bridge. As a result, protective action is immediate and an early recovery is made possible. Bypassing of the bridge is done by freewheeling, with an auxiliary GTO switch or with one of the main GTO switches. Diversionary action is done through the bridge by changing the mode of operation of the bridge from rectifier to inversion, or conversely.

Abstract: In a load commutated inverter (LCI) motor drive, the motor is started from a rotor rest position by modulating the rotor winding with a field current at a constant rate to induce stator voltages which are detected in terms of signs, so as to identify the rotor rest position. The induced stator voltages are used to select an initial pair of thyristors of the inverter to be turned on in the firing sequence for the chosen direction of rotation under normal operation of the drive.

Abstract: To a static VAR generator of the split reactor type, a scaled down model is associated to be controlled concurrently with the static switches of the split reactor and to generate under proportional line voltage a simulated reactive current which is matched with the actual reactive current to detect a flashover across one of the two halves of the split reactor.

Abstract: A reluctance motor control system is stabilized by a load angle feedback control loop provided by a computation of the load angle from sensed voltage and current on the terminals of the motor with the assist of a derived frequency signal. The motor is operated at most efficient load angle in motoring or braking, while the motor voltage is being controlled so as to maintain the desired load angle as the speed and/or load vary.

Abstract: In an induction motor drive controlled by SCR devices connected in the AC power supply phase lines of the motor, a plurality of channels establish, on a common input to a digital gate pulse generator of the SCR's, various signals occurring in the course of the motor drive operation. These signals relate to motor operating modes, such as soft start tripping, current limit. A central large scale integrated (LSI) chip responds digitally to such common input so as to establish the required firing angle at any instant and for any situation.

Abstract: In a hybrid switched-capacitor controlled-reactor static VAR compensator including a fixed-capacitor, hysteresis on switching-OFF a switchable capacitor of the capacitance bank is performed with a minimal fixed-hysteresis at the entrance of the standby region and with a temporary and variable-hysteresis in relation to any operating point in the standby region whenever maintaining the capacitor OFF is required. Since the fixed-hysteresis operates most often to prevent switching-OFF of the capacitor while the variable-hysteresis will operate less often, the losses at standby are minimized during thyristor-switched capacitor operation through most of this.

Abstract: A variable frequency adjustable speed motor drive allows restart of a spinning induction motor by initially increasing the frequency of the associated inverter while keeping the DC voltage source thereof low, then by decreasing the frequency of the inverter while monitoring the effective motor impedance V.sub.DC /I.sub.DC or V.sub.AC /I.sub.AC until the latter jumps at an initial level indicating matching of the frequency with the motor spinning speed. Thereafter, the DC voltage is restored in magnitude and the inverter is increased in frequency to match the desired motor speed.

Abstract: In a load commutated inverter system, the recovery time of the outgoing static switch is extended by applying an auxiliary commutation voltage in series with the associated phase line. This action is triggered in response to the gating signal of the on-coming switch during a time interval initiated before the expiration of the overlap time interval. Its duration extends by a predetermined amount beyond the normal recovery time of the outgoing switch.

Abstract: A UFC is controlled with polar coordinates, a phase checked loop combining with an angular demand to establish a predetermined and tuned sequence of switch combinations between the converters of the UFC, to generate between the output phase-loads the desired voltage vector.

Abstract: The direction of rotation of a three-phase voltage is determined by simultaneous reading of counters triggered by the respective phase zero crossings. Such determination is used in an AC motor drive to dispense of using a tachometer.

Abstract: An induction motor drive control system is controlled according to a torque demand and a rotor flux amplitude demand while using only a shaft position feedback and providing an open loop equivalent of a vector voltage control approach to the control of the induction motor.

Abstract: In an auto-sequential commutated current source inverter (ASCI) system, an auxiliary bridge of thyristors is connected between auxiliary terminals, and a capacitor is charged and discharged resonantly by controlling a corresponding auxiliary thyristor of the bridge to connect the capacitor between the DC terminals and the AC terminals through the bridge in order to charge the capacitor at a precommutation level, whereby commutation of a main thyristor is effected at a reduced peak voltage, and no voltage clamp measure is necessary.

Abstract: The present invention relates to an AC motor drive including two sets of inverters, wherein one transformer is converted on the output of one of the two inverters, the output of the transformer being connected in series with the output of the other inverter.

Abstract: A three-phase matrix converter including switches having snubber circuits associated thereto, is provided with a common voltage clamp capacitor for limiting the voltage applied to the snubber capacitor, and energy is accumulated in the clamp capacitor which is controllably dissipated, in particular by providing energy to auxiliary elements of the overall system.

Abstract: A constant voltage voltage-source inverter of a motor drive includes in its DC-link the combination of diode means, a GTO device and an auxiliary thyristor, the GTO device and the auxiliary thyristor upon transferring to the regenerating mode being cyclically controlled for conduction concurrently with the thyristor of the AC/DC converter so as to match the (voltage-current) domains converter and input of the inverter. Conduction of the GTO device is interrupted before each cyclical control thereof to allow recovery.Initiation of GTO and auxiliary thyristor conduction upon mode transfer is retarded to allow settling of the system before firing the thyristors of the AC/DC converter with a different firing angle.