Abstract: A method and apparatus for compensating for deviations in the alternating voltage produced by a PWM inverter. The necessary sequence in which inverter components must be triggered results in voltage error pulses that accumulate over time and result in deviations from ideal voltage at motor terminals. By allowing the error pulses to continue and adjusting the trigger times to compensate for the error pulses, the effect of the error pulses is negated and the voltage deviations are eliminated.

Abstract: A power-off electromechanical brake employs a friction disk compressed between a ferromagnetic clapper plate and a pressure plate. An electromagnet may pull the clapper plate away from the friction disk or the pressure plate and clapper plate may be separated by free floating spacer elements held within a rotating race positioned between the clapper plate and the pressure plate. In a first mode, cavities in the clapper plate receive spacer elements held within the race and the friction disk is compressed. In a manual release mode, the spacer elements no longer engage with the cavities and separate the pressure plate and clapper plate.

Abstract: A memory system uses standard memory devices not normally supporting parity bits. Parity bits for multiple memory devices are stored in a dedicated parity device shared among multiple memory devices. Inadvertent erasure of the parity information, when writing to a single memory device, is prevented by a prereading of the parity device prior to a writing to the single memory device. Special circuitry stores the preread parity information and merges it back with the calculated parity bit for the written data to preserve complete parity information.

Abstract: A communication system for power monitors and the like includes a plurality of communication nodes connected in series. A technique is provided for automatically detecting the status of the system, including the need to configure the communication nodes or identify the presence and location of a fault. Further, configuration of the nodes is automatically performed as required, and the location of faults is visually represented to assist an operator.

Abstract: A heat sink apparatus including a fluid conduit within a body portion wherein the body portion includes at least first and second walls which are in different planes, each wall forming at least one mounting surface, the conduit passing though each wall and, the apparatus also including at least two electronic devices, at least one device mounted to each of the mounting surfaces for dissipating heat, the assembly having a relatively small volume.

Abstract: An auxiliary switch provides an output or feedback signal indicative of the position or logical state of a contactor, disconnect or other principal device to which it is coupled. The switch is formed as a modular unit which can be fixed directly to the principal device, and is actuated by movement of elements within the principal device. An optical switch set within the auxiliary switch includes an emitter and detector pair aligned in mutually facing relation. An actuator is movable with the principal device and supports an optical shield. The actuator displaces the shield between a position clear of the optical path and a position interposed between the emitter and detector to change the state of the auxiliary switch. A power supply circuit may be housed within the switch for supplying power to the optical switch and to output circuitry. The device is particularly tolerant to contamination and can reliably output low level logic signals indicative of the state of the principal device.

Abstract: An industrial control system employs a primary and secondary controller each having a processor and at least one I/O data table. Updating of the secondary processor's I/O data table is performed prior to the same data being transmitted to the controlled process. This eliminates possible retrogressive control at the time of switch-over of control from the primary industrial controller to the secondary industrial controller. Additional I/O data tables may be provided in each of the primary and secondary industrial controllers. In the case of the secondary industrial controller, this duplicate I/O data table temporarily holds data until the transmission is complete preventing the partial update of the working I/O data table of the secondary industrial controller. The duplicate I/O data table in the primary industrial controller allows simultaneous outputting of the I/O data transmitted to the controlled process without corruption while the user program of the primary industrial controller resumes execution.

Abstract: A method and apparatus for eliminating greater than twice motor over voltage by altering modulating signals provided to a PWM controller which in turn provides firing pulses to a PWM inverter. The modulating waves are altered by either tying them to positive or negative DC buses or limiting their maximum magnitudes when their instantaneous characteristics are known to cause greater than twice overvoltage. The modulating waveforms are altered in a symmetrical fashion so that the resulting fundamental terminal voltages remain essentially unchanged.

Abstract: A flexible coupling device is disclosed adapted to connect a first rotatable shaft with a second rotatable shaft. The coupling device generally includes a pair of opposing hubs, each of which is adapted to be secured to a respective shaft. A continuous and flexible coupling element extends between the hubs. The coupling element is nonremovably associated with a pair of inner clamp rings, each adapted to be connected to one of the hubs. The coupling element can be molded about the inner clamp rings and can be adhesively secured to the rings.

Abstract: An inductive element in the form of a shorting turn is added to the rotor of a permanent magnet synchronous motor. Changes in inductive coupling between the rotor and a stationary coil as the rotor rotates permits inductive measurements to be used to deduce rotor position information such as position velocity and acceleration.

Abstract: A brushless DC motor drive is disclosed which includes drive and control circuitry incorporated into an integrated drive unit. The drive circuitry includes a ground offset or signal conditioning circuit which receives command input signals from a command device and corrects for variations in ground potential between the power source and to the drive. The corrected command signal is used for closed-loop velocity control of a brushless DC motor. The signal conditioning circuit also provides a reference voltage signal for use by a controller which controls the drive circuitry. The command input signal is also applied to an energy conservation circuit. The circuit applies power to the control circuit only when the command is above a preset threshold. When the command is below the threshold level, power is interrupted to the control circuit to reduce the energy consumption of the system.

Abstract: An elastomeric coupling system for securing axially aligned driving and driven shafts includes a pair of hubs coupled to one another by an annular flexible coupling element. The hubs are fixed to respective driving and driven shafts, and the coupling element is then secured between the hubs by anchoring assemblies. Each anchoring assembly includes anchoring members which are fixed to respective hubs by fasteners received in the hubs. The fasteners are oriented generally transverse to the aligned axes of the shafts, providing ready access for installation and servicing. As the anchoring members are secured about the hubs, axial and radial loads are exerted on peripheral beads of the coupling element to produce retaining forces sufficient to withstand considerable torsional loading during use.

Abstract: An AC--AC multi-module matrix PWM converter includes one to a plurality of phase banks within which are provided architecturally identical basic circuit modules of single phase output AC--AC matrix converters. Each basic converter module includes three-phase AC inputs and two output terminals. The modules may then be interconnected in series or parallel with other modules within a phase bank to increase the output voltage or current respectively of the phase bank. The differential power module structure and the differential phase PWM modulation scheme increases the output voltage by 15.5% in comparison with 120.degree. phase modulation. Individually designed and tested phase banks can be further connected to a higher power symmetric three phase system or multiphase system for various AC load and AC motor controls. The modular structure permits standardization of the power electronics design and manufacture at system level.

Abstract: A bearing assembly includes an inner ring and outer ring defining opposed raceways having a plurality of bearing elements disposed therebetween. The bearing assembly includes an improved sealing arrangement having multiple primary seals for providing sealing with the rotating inner ring. In preferred embodiments, the multiple seals include a rolled riding seal and an oblique contact seal having a center lip therebetween. Unlike the other two primary sealing lips, the center lip preferably provides no more than light engagement with the bearing inner ring.

Abstract: A bearing assembly includes an inner ring assembly defining a bore for receiving a shaft, and an outer ring assembly disposed radially outward from the inner ring assembly. A plurality of rotatable bearing elements are disposed between the inner and outer rings and permit the rotation of the shaft and inner ring relative to the outer ring. An annular member extends from the outer ring assembly radially inward toward the inner ring assembly. The annular member is secured to a housing surrounding the outer ring and axially bounds an area between the inner ring and the outer ring in which the plurality of rotatable bearing elements are disposed. A first seal is disposed outside the bearing area to seal a chamber between the annular member and the inner ring. The first seal permits egress of lubricant from the chamber but inhibits ingress of foreign matter therein.

Abstract: An improved speed reducer assembly is provided. The assembly comprises an input shaft, an output shaft and a gear train interfacing the input shaft and the output shaft to effect a desired angular velocity ratio between the input shaft and the output shaft. A housing defines an interior area in which the gear train is disposed, the housing being configured to hold lubricant within the interior area. A pressure sensing device is mounted on the housing in communication with the interior area. The pressure sensing device is configured to output a pressure signal responsively to fluid pressure within the interior area. A second housing may be provided to sealingly enclose a portion of the pressure sensing device outside the speed reducer housing.

Abstract: A substrate (10) of a semiconductor device includes a power section (12) and a control section (14). The power section includes doped regions (16, 18, 20) and terminals (22, 24, 26) which define power devices such as transistors or SCRs. The control region also includes doped areas including a parasitic collector (32). A minority carrier current (62) flows from the doped regions of the power section to the collector of the control section when the power device to substrate junction is forward-biased. A self-biased moat assembly (40) includes a first doped region (42) between the doped regions of the power and control sections under which the parasitic minority carrier current flows. An electrical connection (46) connects the moat first doped region (42) with a moat second doped region (44). The self-biased moat assembly is isolated from ground such that it is self-biased negative in accordance with internal operating conditions of the semiconductor device.

Abstract: A multilayer circuit board system or laminated circuit board system for use in a motor controller includes at least two motherboards, at least one power substrate circuit board, and a capacitor circuit board. The circuit boards are mounted in an aperture or trench within each mother board. The power substrate module circuit board includes a mounting area provided in a recess, window or portion of the circuit board where the circuit board is only a single layer thick. The single circuit board layer at the mounting area provides a heat conductive yet highly electrically insulated mounting area for receiving a heat sink. The heat sink can be mounted on a side opposite the electrical device. The capacitor circuit board, power substrate circuit board, and mother circuit boards are interconnected without the use of external connectors or wires. The use of two mother boards increases the rigidity of the circuit board system.

Abstract: A modular structure for attachment to a rail includes securement members received and supported on either side of the rail. The rail includes a support web and parallel side flanges. The structure is constructed from a molded plastic base unit to which metallic securement members are assembled. The base unit preferably includes a rigid side and a flexible side. The securement members are substantially identical to one another, facilitating manufacturing and assembly, and reducing the number of different parts in the final module. The securement members each include v-shaped slots for engaging the side flanges of the rail. The base unit may be configured as a blank end unit, or may include features for creating terminal blocks, I/O blocks, switches, circuit board supports and the like.