Abstract: A method and apparatus for starting a motor drive into a rotating motor, the method including determining an initial search frequency and search current wherein the current is less than a rated drive current, providing a d-axis flux generating current to the motor at the search frequency and at a magnitude equal to the search current, monitoring a q-axis flux error, decreasing the search frequency until the d-axis flux error is less than a threshold value, thereafter increasing the search current to the rated drive current and, after a flux-up period, providing both q-axis torque producing current and d-axis flux producing current to the motor.

Abstract: A method and apparatus for determining the critical dwell time required between firing pulses generated by a PWM inverter to eliminate greater than twice overvoltage on motor supply lines. Critical dwell time is correlated with line parameters including inductance and resistance per unit length and is then provided to a controller to alter voltages provided to a motor to eliminate overvoltage.

Abstract: A method for retaining a movable contact in a circuit interrupter is applicable to interrupters including first and second contacts, at least one of the contacts being movable. A movable element supporting the movable contact is displaceable between a conducting position wherein the movable contact abuts a cooperating contact to complete a current carrying path through the device, and a non-conducting position wherein the movable contact is electrically separated from the cooperating contact. In accordance with the method, the movable contact is displaced by an interrupt initiation device, and a carrier or retainer is displaced by gas pressure resulting from arcs generated by movement of the contact. The carrier is guided in its displacement within the device housing from a normal operating position to a retaining position. The carrier includes an abutment element that physically contacts the movable element to prevent it from rebounding into contact with the cooperating contact.

Abstract: A multi-tasking operating system for real-time control of industrial processes integrates ladder type programs and state-type programs by viewing each as a series of instructions with an implicit pointer list pointing to the next instruction. A fixed number of instructions of each program task are executed after which the effective pointer to the next instruction is stored toward the next time that task is invoked. Multiple tasks that need to be coordinated can be linked with subtasks that can be guaranteed complete execution by allocating sufficient instructions to those subtasks.

Abstract: A redundant controller employs two controller chassis having replaceable functional modules interconnected electrically within the chassis. System back up modules in the chassis coordinate the switching of control from a primary to a secondary chassis according to chassis redundancy state information of the chassis stored in the backup modules and module redundancy state information stored in the modules unique to the modules.

Abstract: An apparatus for receiving and modifying a PWM trigger signal such that consecutive ON and OFF periods have durations at least as long as a critical dwell time where the critical dwell time is the minimum time required to avoid greater than twice overvoltage. The trigger signals are modified by, each time a trigger signal changes from low to high, providing a minimum pulse signal which remains high for the greater of a critical dwell time or the time over which the trigger signal remains high, when the minimum pulse signal changes from high to low, providing a maximum pulse signal which remains low for a critical dwell time, adding the maximum and minimum pulse times using a logical AND gate and providing the output of the AND gate as a modified trigger signal.

Abstract: An apparatus for essentially eliminating transmission line reflected waves and standing waves and for reducing common mode transient currents for use with a three phase motor controller, the apparatus including a common mode choke in series with a filter network between an inverter and a motor, the filter including three inductors and three resistors, the inductors and resistors together forming three inductor-resistor pairs, each pair including an inductor in parallel with a resistor, each pair linked to a separate one of three transmission supply lines which link the inverter to the motor, values of the resistors and inductors selected according to transmission line theory.

Abstract: A programmable controller reduces the power used by the relays. The controller design permits energization of relay coils without subsequent maintenance of the relatively high voltage required for energization. The design permits the voltage across the relay to be lowered to an activated relay coil maintenance level with a design that minimizes the space required for the relay circuitry.

Abstract: A circuit card of an industrial controller may be removed or inserted under power without loss of memory or disturbance to the power supplies of other modules through the use of a power failure signal derived from shortened pins on the connector between the card and the industrial controller. The power failure signal activates a timer delaying connection of the board components to power until the physical connection between the card and the industrial controller has stabilized. At this time current drain is ramped up by a controlling series FET. Upon removal of the card, the power failure signal causes outputs of an on-board microprocessor to be pulled to particular states necessary to prevent disturbance of a battery backed-up RAM and to eliminate current flow through protection diodes on other memory type devices attached to the microprocessor.

Abstract: A method and apparatus for minimizing motor instability under no load conditions, the method including identifying instability by comparing consecutive current half cycle periods and, where the difference between half cycle periods is sufficiently large, determining that instability exists and modifying controller modulating waveforms by reducing waveform magnitude until stability is achieved. Preferably the apparatus for achieving stability includes only a single current zero crossing sensor to minimize hardware costs.

Abstract: A bidirectional lateral insulated gate bipolar transistor (IGBT) includes two gate electrodes. The IGBT can conduct current in two directions. The IGBT relies on a double RESURF structure to provide high voltage blocking in both directions. The IGBT is symmetrical, having an N-type drift region in contact with an oxide layer. A P-type region is provided above the N-type drift region, having a portion more heavily doped with P-type dopants. The double RESURF structure can be provided by a buried oxide layer, a floating doped region, or a horizontal PN junction. The IGBT can be utilized in various power operations, including a matrix switch or a voltage source converter.

Abstract: A loosening-resistant threaded fastener system and method of use includes a washer that is axially movable on a threaded stud, a threaded nut having threads which cooperate with the threaded stud, and a washer anti-rotation mechanism to prevent the washer from rotating on the stud about a fastening axis. One of the washer and the nut may include a plurality of protrusions while the other of the washer and the nut has a plurality of detents. The protrusions and the detents engage one another at a plurality of angular positions. Rotating the nut on the stud while in contact with the washer results in distinct, audible clicks which may be counted to obtain a pre-determined tightness.

Abstract: Inter-operability of products connected together to form an industrial control system is determined by defining each product as a set of services describing points of interface between the products and by determining complementary services necessary for inter-operability from a table listing complementary services. A new product may be evaluated for inter-operability by comparing its services to services of products with which inter-operability is desired. In one mode of operation after definition of the products in which inter-operability is desired, a necessary list of services is compiled from a database and translated by a relationship map to complementary services which define a virtual product having the desired inter-operability. Inter-operability of an entire control system may be thus modeled prior to construction.

Abstract: An industrial controller provides a primary controller and a redundant secondary controller and allows switchover between the controllers in the event of a failure in the primary controller. The process of qualification of the secondary controller in which its programming is made to match the primary controller may be inhibited to permit the secondary controller to maintain a clean version of an upgraded program executing on the primary controller. The clean program may be reverted to in the event an upgrading of the program in the primary controller is unsuccessful. Switchover is permitted even though the qualification of the secondary controller is not enabled.

Abstract: A method and apparatus used with a field oriented motor controller for providing corrected transient inductance estimates during normal motor operation. The invention monitors q-axis feedback and command voltages and, based on an error therebetween, modifies a transient inductance estimate to compensate for the error and force the feedback voltage to equal the command voltage thereby facilitating field oriented control. The invention can be used either during a commissioning procedure to provide an inductance correction table for use during normal motor operation or can be used during normal motor operation to tune the inductance estimate.

Abstract: On-line upgrading of a primary industrial controller is provided through the use of a secondary industrial controller that may assume control of the process controlled by the primary industrial controller. A switch-over of control is orchestrated by a system back-up module that may detect removal of the functional components of the primary industrial controller to initiate the switch-over. Determination of removal of functional modules may be provided by a periodic polling of the functional components on the interconnecting communication link. The system back-up module designates one of the functional modules to poll the system back-up module so that complete coverage of removable components may be had.

Abstract: A motion controller includes an input for receiving data corresponding to moves in a cycle of a multi-axis machine. The controller controls electric motors of the machine in accordance with positions set forth in a path planning table. The path planning table is generated from the data by applying a curve defining equation and integrating an alpha variable therein. The alpha variable corresponds to a velocity to acceleration ratio and is adjustable to allow the calculation of a new path planning table having a velocity and acceleration profile shifted from an initial velocity and acceleration profile to allow for optimization of motor performance. A method of path planning having user tunable parameters is also provided.

Abstract: A redundant controller employs connection-based messaging to ensure reliability and determinacy in communications. The need to close connections and reopen connections with a backup module when control switches from a primary controller to a secondary controller is eliminated by keeping the secondary controller updated as to the connections that have been opened and having the secondary controller assume the connection identification numbers of the primary controller upon switch-over.

Abstract: An apparatus for converting three phase AC supply line voltages to DC voltage on a DC bus, the apparatus including a master converter subsystem and at least one slave converter subsystem wherein each subsystem includes a current regulator, a PMW modulator and a converter, the master converter linked to the supply lines and the slave converter linked to the supply lines via intermediate lines, each regulator receiving a current command signal and generating modulating signals, each modulator using a carrier signal and modulating signals from a corresponding regulator to generate control signals to control a corresponding converter, the intermediate lines linked to a common mode choke for essentially eliminating common mode currents in the intermediate lines.

Abstract: An inductive proximity sensor and a method of proximity sensing are described that permit targets of interest to be detected despite the presence of external magnetic fields due to AC or DC sources, such as resistive welding machines. The sensor has a pair of matched coils positioned adjacent to one another along a common central axis. The coils are coupled in series with oscillator and detecting circuitry, that also serves to drive a switching device. The coils are wound for current flow in opposite directions and produce oscillating electro-magnetic fields for detecting the targets in response to signals from the oscillator and detecting circuitry. Currents in the coils induced by strong external magnetic fields produces an additional components of the coil field which essentially cancel one another. The sensing field of the coil assembly may be shaped and directed by cooperation of the fields of the two coils and by appropriate shielding around one or both coils.