Other

Fmtt, Inc.

Edward Herbert

Stephen E Cebry

John D Repp

Ian R Smith

A frayed cable scaling tool is made by fraying the end of a cable so that it forms a wire brush. A collar or other way of keeping the cable from unraveling too much is necessary. When powered by a pneumatic saw power tool, the scaling tool is very effective at removing scale, rust, carbon, or other debris. The flexibility of the cable allows the frayed end of the cable to move vigorously in a random motion, which is effective for scrubbing. For some applications, it is preferred to enclose the cable and/or the collar in a guide tube.

Frayed cable scaling tool

A valve for saving water and energy in a shower uses a wax motor as an actuator. Below the activation temperature of the wax motor, the valve is open and the shower water flows. When the water reaches the activation temperature, the piston of the wax motor extends and turns off the water in the shower. The person taking the shower then can restore flow by turning a handle. The shower can then be turned off and on at will by turning the handle manually. When the valves cools down, it resets automatically.

Water and energy saving thermostatic valve

A switched-capacitor circuit has two capacitors and two MOSFETs that cross-couple the capacitors, connecting the anode of one to the cathode of the other, and vice-versa. When either MOSFET is on, the capacitors are in series; the order alternates as the MOSFETs alternate. A reversing cyclical voltage suitable as a primary drive for a transformer is generated. If the MOSFETs alternate with no dead-time, a square-wave excitation is generated. With off-time, a pwm excitation is generate. Charge is maintained on the switched-capacitors using a symmetrical common-mode inductor. A bifilar winding is center-tap as its input, and the ends of the bifilar winding are connected to the capacitors. The capacitors are effectively in parallel. Because the charging current flows and returns through each leg of the inductor equally, it cannot magnetize the inductor core or cause any flux change. Because any voltages induced in the windings are common-mode, flux change in the core does not affect the charging current. The ac voltage generated when the capacitors switch is across the full inductor. Not only does the inductance attenuate any noise, the center-tap is between equal and opposite negative and positive voltages, which cancel. There is very little noise at the input. The circuit is reciprocal, so it can be used to rectify a transformer output. Two can be used as a bi-directional transformer isolated power converter. Several modules using 1 to 1 transformers can be stacked for a power converter having a higher ratio of input to output voltage.

Symmetrical power converter

A minimalized power converter has a square-wave voltage source operating at 100 percent duty-ratio, a series inductance and a rectifier. A high frequency square-wave power distribution system comprises a plurality of minimalized power converters connected by a common ac power distribution link. Because the ac power distribution link carries current at a high frequency, the square-wave may be degraded by the stray inductance with distance. Re-squaring circuits along the length of the ac power distribution link operating synchronously restore and preserve the integrity of the square-wave. The minimalized power converter is very flexible and has very fast dynamic response, being able to make very fast controlled current transitions from any current to any other current, including zero or current reversal (same voltage, opposite current flow).

High frequency square-wave power distribution system

It is known to insulate bus bars to reduce shock and arc-flash hazards. However, failed or damaged insulation may not be noticed, possibly presenting a greater hazard as it is unexpected and therefore not prepared for. A metal cladding at earth ground enhances the safety to personnel and reduces the likelihood of a more serious line to line arc-flash. Still better is the use of a guard conductor intermediate between the hot conductor and the earth ground insulated from both. Not only does it introduce an additional layer of insulation, it also provides a way to continuously monitor the integrity of the insulation. A resistor divider establishes the nominal voltage on the guard conductor. A departure from nominal voltage indicates a potential fault. The guard conductor can also be used as a node for connecting other sensors, or one of the insulation layers may be of thermally sensitive polymer, to detect hot spots.

Method and apparatus for reducing shock and arc-flash hazards in power distribution systems

The interleaved common mode transformer is a transformer particularly well suited for providing low voltage, high current dc outputs. Improving the efficiency of low voltage, high current transformer circuits requires a multi-faceted approach. Ac terminations and ac currents in connecting circuitry are particularly troublesome, so the input and output terminations of the transformer are dc. To utilize the winding fully, a common-mode push-pull configuration with common mode capacitors is used. Stray capacitance is less of a concern than leakage inductance at low voltages, so the windings are highly interleaved. Separate parallel secondary windings are used, an ac winding primarily for the ac currents, and a dc winding primarily for dc currents and heat sinking. The ac windings are thin; approximately two times the penetration depth. The dc windings are substantial, for low voltage drop and good heat sinking. For economical construction with minimum height, plated circuit board fabrication methods and materials are used for the windings. 100 percent duty-ratio switching is preferred to minimize core losses and reduce filtering requirements, as the filters are lossy.

Interleaved common mode transformer with common mode capacitors

A 3-phase pfc 100% duty-ratio buck converter and a 3-phase 0% duty-ratio boost converter can be used in parallel with their outputs in series to greatly reduce the ripple voltage in the output. They can also be used in series with their outputs in parallel to greatly reduce the ripple current in the output. A 3-phase 0% duty-ratio boost converter having isolated primary circuits for each phase is used when the inputs are in series.

Power factor corrected 3-phase Ac-dc power converter using natural modulation

An interposer is made of nested drawn copper shells with insulation between them. The shells are etched using methods of ordinary printed wiring fabrication, but being three dimensional, straight runs from the die to the motherboard can be made optimally short and wide without passing through any vias. Some shells can extend upward for top connections, and vias and crossing landlines can be used as required in the areas away from the die.

Interposer and method for making interposers

This invention teaches power factor corrected 3-phase ac-dc power converters in which the duty-cycles are determined by 'natural modulation', that is, they are forced by a fixed algorithm that has been optimized for efficient switching. The duty-cycles do not regulate the output voltage but they do force the input currents to be proportionately correct for good power factor. A feedback control circuit modulates the effective turns-ratio of a variable dc-dc transformer to regulate the output voltage. For a buck converter, the most efficient duty-cycle is 100%, that is, the buck switch is always on. For a boost converter, the most efficient duty-cycle is 0%, that is, the boost switch is always off. '100% duty-cycle' as defined for a buck 3-phase ac input means that there is no off-time. The switch duty-cycles are as follows: The duty-cycle for the phase with the highest voltage magnitude (the dominant phase) is 100%, and sum of the duty-cycles of the other two phases equals 100%. &#x201c;0% duty-cycle&#x201d; as defined for a boost 3-phase ac input means that the input is never short circuited line to line. The duty-cycle for the switch for the phase with the highest voltage magnitude (the dominant phase) is 0%, and switches of the other two phases modulate to control their respective input currents.

100% duty-cycle buck-derived and 0% duty-cycle boost-derived power factor corrected (PFC) 3-phase Ac-Dc power converters

Many power converters operate with an input voltage that has a normal range of voltage that is quite narrow, for example, commercial ac voltage or from a regulated upstream power converter. To accommodate transient and abnormal conditions, power converters are often designed for a wide range of input voltage, which seriously compromises their efficiency at nominal voltage. This invention teaches a power converter that is optimized for the normal operating voltage range. A variable dc-dc transformer and a buck derived modulator are used in series. The buck circuit is most efficient at high duty cycles, and for normal input voltage, the buck converter may be saturated at 100 percent duty cycle. The duty cycle of the buck converter is reduced to accommodate over voltage transients. Efficiency is compromised, but the duration is short, so that is acceptable. For normal and under voltage conditions, the effective turns ratio of the variable dc-dc transformer is modulated to effect control. At normal input voltage, the effective turns ratio is nearly maximized, for optimum efficiency. At lower voltages, the efficiency is compromised, but the duration is short, so that is acceptable.

'Natural modulation' for maximizing efficiency in power converters

A power factor corrected (pfc) ac-dc converter has a modified boost input and a modified buck output. Unlike the prior art boost input, the boost switch returns to the output, not to ground. Unlike the prior art buck output stage, a third switch connects to the input. This allows much of the input current to pass through the converter to the output. There is no input current measurement, but nearly ideal power factor correction is achieved through 'natural modulation.' A preferred pfc ac-dc converter uses a variable dc-dc transformer on its output, as a post regulator, to provide dielectric isolation and to provide voltage level shifting. The output of the pfc ac-dc converter has the control characteristics of a buck converter, so it is a natural mate for the variable dc-dc transformer. An ac-dc buck converter is most efficient at its maximum duty cycle. It cannot regulate for a lower input voltage, but it can reduce its duty-cycle to control for higher input voltages. A variable dc-dc transformer is most efficient at its maximum ratio. It cannot regulate for a higher input voltage, but it can reduce its effective turns ratio to control for a lower input voltage. With a small overlap in their control ranges, both parts of the power system can operate at maximum efficiency. The variable dc-dc transformer controls the output voltage for nominal and low input voltage. The ac-dc buck converter limits over-voltage transients.

Power factor corrected single-phase AC-DC power converter using natural modulation

A dual source MOSFET comprises a large number of cells diffused into a substrate. The cells are divided into two regions with separate sources and gates but having a common drain connection, the substrate. It is preferred that the source regions be highly interdigitated so that the current at the silicon to metal interface is sufficiently diffuse so that the source from which it originated is indistinguishable, and in switching from one source to the other causes no significant difference in the current density or distribution at the drain connection, provided that the sum of the source currents is constant. The same construction provides a superior ac switch, though no drain connection is needed.

Dual source MOSFET for low inductance synchronous rectifier

In a fast power converter with distributed output capacitors with parasitic impedances between them, the settling time of the output voltage is too long, making voltage unsuitable as a control input. The charge on each of the distributed output capacitors can be measured, preferably differentially, in a summing network in which the conductance of each of the summing resistors is proportional to the capacitance of the capacitor with which it is associated. The charges can be summed as a total charge control input for the fast power converter. The total charge control is very sensitive to changes in the output current, and is insensitive to lags, ringing and/or oscillations of the voltages among the distributed capacitors. If the output capacitor of a VRM is small compared to the total capacitance, the impedance of its connector is largely mitigated.

Total charge measurement

A variable transformer has an effective turns ratio that can be varied by electronic switching. By varying the effective turns ratio, the output voltage can be controlled precisely for a varying input voltage and load regulation. The variable transformer is a modular transformer in which one or more of the modules can be effectively removed from the variable transformer by turning on an ac switch so as to short-circuit the secondary winding of the module. When the ac switch is on, the rectifiers of the module must be turned off, if they are synchronous rectifiers. If they are diodes, they will be off by being back-biased when the ac switch is on. Improved transformer modules are shown having reduced leakage inductance.

Variable transformer

A three phase buck power converter having input power control is described. The power converter uses a three input buck converter comprising switches for each phase, a catch rectifier, an inductor and an output capacitor. The duty cycle of the three switches is constrained to have a sine function relationship that may be derived from the input voltage wave form or from a reference oscillator. When so constrained, the input currents have high power factor. The output is a precise, high quality dc voltage, comparable to the output of a dc&#x2014;dc buck converter, and the dynamic response is comparable. Voltage mode and current mode controls are shown, as is a precise line regulation feed forward for the voltage mode embodiment. The three phase buck power converter may be operated in reverse as a three phase boost converter, as they are reciprocal. A three phase ac&#x2014;ac converter may have a three phase buck converter as its input and a three phase boost converter as its output.

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Canton, CT, United States of America

Edward Herbert