Abstract: A method for operating a push-pull converter in an above resonant frequency operating mode, where the above resonant frequency operating mode produces a switching frequency that is higher than the natural operating resonant frequency of the converter circuit. As a result, the resonant period is longer than the turn-on period of each of the switches in the primary circuit. The push-pull converter has two power switches operating in alternating sequence. The push pull converter also includes a transformer with a primary winding coupled to the power switches and a secondary winding coupled to a secondary circuit, and an output capacitor. The method also includes generating an operating resonant frequency from a leakage inductance of the transformer in series with a an input capacitance; and generating a switching frequency for the power switches that is higher than the operating resonant frequency.

Abstract: A power converter includes multiple phase circuits, each phase circuit includes a power switch for delivering power to an output of the power converter, a current sensor connected to the power switch for sensing a current in the power switch, a duty cycle controller having an output connected to the current sensor, and a low pass filter connected to the current sensor. The low pass filter is configured to produce a substantially direct current signal proportional to the average current in the power switch. Further, the duty cycle controller is configured to receive the direct current signal and control a duty cycle of the power switch in response to the direct current signal thereby balancing the currents in the phase circuits.

Abstract: A circuit for controlling the operation of synchronous rectifiers. The circuit delays the turn-off of the synchronous rectifiers in accordance with the load current. The magnitude of the load current is examined to determine which of a plurality of delay elements is selected to delay turn-off of the synchronous rectifiers. Delay is accomplished by holding up for a predetermined time period one of a plurality of control signals utilized to determine when the synchronous rectifier should be turned-off.

Abstract: An apparatus and method for a modified horizontal directional drilling assembly for drilling pipe into a drilling surface. The drilling assembly comprises a power unit for supplying power to the assembly, a thrust frame adapted to be moved between a position substantially parallel to the drilling surface and a position substantially perpendicular to the drilling surface and a means for moving the thrust frame. The drilling assembly further comprises a rotary and carriage assembly mounted on the thrust frame. The rotary and carriage assembly is adapted to apply rotational, thrust and pull-back forces to the drill pipe. The drilling assembly is adapted to drill pipe into the drilling surface at any angle relative to the drilling surface between substantially parallel to the drilling surface and substantially perpendicular to the drilling surface.

Abstract: A power converter circuit includes an input switching circuit, an isolation circuit, a rectifier circuit that includes a least a pair of rectifiers, and an output circuit. The input switching circuit receives a first voltage and generates an AC voltage. The isolation circuit has a primary side configured to receive the AC voltage from the input switching circuit and a secondary side. The secondary side communicates with the rectifier circuit and the output circuit. The output circuit includes a secondary inductor and a diode. The secondary inductor communicates with a primary inductor and either the rectifier circuit or the secondary side. The diode communicates with the primary inductor, the secondary inductor, and the rectifier circuit. The secondary inductor inhibits current flow through the rectifier circuit and forces current flow through the diode when no voltage is applied to the primary side of the isolation circuit.

Abstract: A system that, in a natural convection embodiment, comprises a structure having an output cord and a stand coupled thereto for mounting a power module in a substantially vertical orientation. The stand has a base with a first vertical piece extending therefrom to a first fin that is parallel to the base and having a second vertical piece extending from the base to a second fin that is parallel to the base. The power module plugging into the stand defines a first gap along an edge of the first fin adjacent to the first side of the power module and defines a second gap along an edge of the second fin adjacent to the second side of the power module. The stand allows vertical heat dissipation generated by the power module with air flow vertically through the first and second gaps. Alternatively, an air fan is included for forced convention.

Abstract: An apparatus and method for reducing common mode noise capacitive coupling from a primary winding to a secondary winding in a transformer. In an embodiment, the primary winding has two terminals and a plurality of coil turns therebetween formed by a plurality of PCB layers sandwiched together, each having at least one of the coil turns formed thereon. The coils turns are connected in a predetermined way to form the primary winding. One terminal of the primary winding is connected to a coil turn on a first one of the PCB layers, and the other terminal is connected to a coil turn on a second one of the PCB layers. The PCB layers are stacked to form the primary winding. The secondary winding or windings are positioned adjacent to a selected one of the stacked PCB layers that is in a position between the first and second PCB layers.

Abstract: A circuit for controlling the operation of synchronous rectifiers. The circuit delays the turn-off of the synchronous rectifiers in accordance with the load current. The magnitude of the load current is examined to determine which of a plurality of delay elements is selected to delay turn-off of the synchronous rectifiers. Delay is accomplished by holding up for a predetermined time period one of a plurality of control signals utilized to determine when the synchronous rectifier should be turned-off.

Abstract: An auger boring machine having a drive mechanism for moving the machine along a desired direction of travel includes a drive motor having a shaft and a pinion mounted on the shaft. A method for manufacturing a track for such a boring machine includes providing a track base rail adapted to support the auger boring machine and arranging the base rail along the desired direction of travel of the boring machine. The method also includes cutting a gear rack which includes a plurality of gear teeth along one side that are adapted to mesh with the pinion of the drive mechanism, and a flexibility notch on the side opposite the gear teeth. The gear rack is attached to the base rail with the gear teeth oriented so as to engage with the pinion of the drive mechanism.

Abstract: The present invention provides an electromagnetic component formed from adjacent conducting layers of a multi-layer PCB and two additional conducting layers in contact with the PCB. The inventive component includes one or more winding turns formed by connecting the multiple layers of the multi-layer PCB with conductive vias and by connecting the additional conducting layers to respective top and bottom surfaces of the PCB. In one embodiment, one of the conducting layers is soldered to a top conducting layer of the PCB and the other of the conductive layers is soldered to a bottom conducting layer of the PCB, effectively increasing the cross-sectional area of the top and bottom winding layers. In another embodiment, the additional conducting layers are separated from the adjacent conducting PCB layers by a layer of insulation, permitting the additional conducting layers to form separate winding turns.

Abstract: A scaling apparatus comprises a hammer component and a pick component which includes a tooth. The apparatus also includes a mechanism for moving the pick component with respect to the hammer component to thereby impart a scaling force to and through the tooth. In a preferred embodiment of the invention, the pick component includes a pick body comprising a first pivot having a pivot axis and a tooth mounted on the pick body. In this embodiment of the invention, the hammer component includes a hammer housing and a second pivot mounted within the housing and adapted to pivotally engage the first pivot of the pick body. This embodiment of the invention also includes a mechanism for rotating the pick body relative to the hammer component so as to impart a scaling force.

Abstract: A circuit for reducing power loss for a soft switching full bridge converter at light loads and enabling very high frequency operation without using a cold plate approach. The circuit preferably includes a resonant inductor and blocking inductor on the converter's primary side arranged so as to provide reduced losses for a zero voltage switching bridge converter. The circuit provides these benefits even for converters having a power transformer with very low leakage inductance. The circuit is not dependent on the presence of a high leakage inductance for the power transformer. The circuit can also be used in soft switching half bridge converters. The circuit can also be used in a hard switching full bridge or half bridge converter for achieving zero voltage switching at reduced cost with reduced losses at light load, if the duty cycle of the converter is set near fifty percent.

Abstract: A method of selectively assembling a printed circuit board (PCB) module intended for attachment to another structure, such as another larger PCB. A plurality of different mounting hardware for a PCB are provided for enabling the selective enhancement of the thermal characteristics of the module. One embodiment provides a conversion kit comprising a PCB having a circuit mounted thereon, lead frames, a baseplate, and open frame and baseplate mounting hardware that, when selectively attached to the PCB, result in an open frame or a baseplate module. The manufacturer of power conversion or other modules can thus manufacture and pretest the board's electronics before assembly into either an open frame or baseplate module, while also providing a conversion kit that includes inexpensive mounting hardware to enable a user to select between assembling a module as either an open frame or a baseplate module.

Abstract: A drive circuit for a synchronous rectifier has a transformer having a main secondary winding and an auxiliary secondary winding. A first switch and a second switch each have a pair of terminals, a terminal of the first switch being connected to the first end of the main winding, a terminal of the second switch being connected to the second end of the main winding, and each remaining terminal of the first and second switch being connected together. A third switch connects between the second end of the main winding and the first end of the auxiliary winding, wherein the third switch periodically closes to connect the main winding and the auxiliary winding in series, a drive voltage being developed by the connected main and auxiliary windings being used to control at least one of the first switch and second switch.

Abstract: A reverse current control system for first power converter having a synchronous rectifier and an output inductance includes a reverse current module. The reverse current module monitors a first voltage that is based on an output voltage of the output inductance and a second voltage that is based on an input voltage of the output inductance. The reverse current module anticipates a reverse current condition based on the first and second voltages. When the reverse current condition exists, the reverse current module prevents current from flowing in reverse through the power converter.

Abstract: The modular master control unit of the telecommunications power system communicates via a data bus with the associated modular rectifier units, distribution unit(s) and battery connection unit(s) to collect operating state information from the neuron processors of those units and store that information in a database. The master control unit also controls the operation of the associated modular units by supplying operating state information, based on values stored in the database. The user interface manager module provides local user interface control over the system by allowing the user through a local display screen and touch pad to read from and write to the database. By downloading an applet to a remote computer running a web browser, the user interface manager allows users at remote locations to perform the same control and monitor functions as a user at the local site. The applet runs within the standard browser and communicates with the user interface manager using TCP/IP protocol.

Abstract: An electrical plug is disclosed with a slidable earth pin that can be manually positioned in a stored position in a plug body of the electrical plug when the electrical plug is not in use. The slidable earth pin is movable in the channel and retained by an interlocking mechanism between the earth pin and the channel on the plug body. The earth pin has a pair of protruding fingers that snap into a first set of grooves in the channel of the plug body in a first position, and that snap into a second set of grooves in the channel of the plug body in a second or stored position. When the earth pin is in its stored position, the physical dimension of the plug is significantly more compact than conventional three pin plugs.

Abstract: A dust collection assembly includes a primary collection assembly and a secondary collection assembly and may be connected to a source of gas having dust entrained therein. The primary collection assembly includes a primary duct having an inlet end and an outlet end. A first apparatus is mounted within the primary duct imparts a swirling motion to the gas which enters through the inlet end of the duct. A second apparatus is located downstream of the first apparatus for removing a portion of the dust entrained in the gas. The secondary collection assembly is in fluid communication with the outlet end of the primary collection assembly, and it includes a plurality of filter bags. The dust collection assembly also includes a fan that is in fluid communication with the secondary collection assembly.

Abstract: A power converter includes a first transformer that has a primary winding and a secondary winding. The secondary winding is coupled to a first secondary side. A second transformer has a primary winding and a secondary winding. The secondary winding is coupled to a second secondary side. The primary windings of the first and second transformers are coupled in parallel to a primary side through respective windings of a transformer that has inverse coupled windings. The secondary windings of the first and second transformer are coupled in parallel. The second secondary side is interleaved with the first secondary side.

Abstract: An electrical plug is disclosed having a rotatable earth pin that can be folded into a plug body by rotating the rotatable earth pin from an unfolded position to a folded position. In the unfolded position, the rotatable earth pin is interlocked with the plug body through a locking tab on a snap lock that latches onto the plug body. To release the rotatable earth pin from its unfolded position, pressure is exerted onto the locking tab to release the snap lock, which allows the rotatable earth pin to move and rotate to a folded position. Locking pins and associated grooves releasably retain the rotatable earth pin in its folded position.