Abstract: An uninterrupted power supply (UPS) device with uninterrupted neutral from input to output utilizes the same converter for converting rectified AC power and battery power to positive and negative high voltage (HV) rails. A simple circuit is utilized for connecting the battery to the conversion components of the PFC circuit without adverse affect on the performance of the PFC circuit, and while holding the battery substantially connected to neutral. In a first embodiment, the circuit comprises a simple combination of four diodes and a pair of high pass capacitors arranged so that in both power line and battery supply modes the battery is balanced around neutral. In a second, preferred embodiment, one terminal of the battery is connected directly to neutral.

Abstract: A power converter includes first and second voltage busses and a neutral bus. A first switching circuit, e.g., a rectifier circuit, is operative to selectively couple an input node thereof to the first and second voltage busses. A balancer circuit is operative to selectively couple the neutral bus to the first and second voltage busses such that relative magnitudes of respective first and second voltages on the first and second voltage busses are controlled responsive to respective first and second rates at which the balancer circuit couples the first and second voltage busses to the neutral bus. A second switching circuit, e.g., an inverter circuit, is operative to selectively couple the first and second voltage busses to a load connected at an output node thereof.

Abstract: An uninterruptible power supply (UPS) includes an AC source port configured to connect to an AC power source, a DC source port configured to connect to a DC power source and a load port configured to connect to a load. A rectifier circuit is operative to selectively couple the AC source port to first and second voltage busses through a first inductance. An inverter circuit is operative to selectively couple the load port to the first and second voltage busses through a second inductance. A bidirectional DC source coupling circuit is operative to couple the DC source port to the first and second voltage busses to provide bidirectional power transfer therebetween, preferably such that a voltage at the DC source port is maintained in a substantially fixed proportion to first and second DC voltages at respective ones of the first and second voltage busses.

Abstract: An uninterrupted power supply (UPS) device with uninterrupted neutral from input to output utilizes the same converter for converting rectified AC power and battery power to positive and negative high voltage (HV) rails. A simple circuit is utilized for connecting the battery to the conversion components of the PFC circuit without adverse affect on the performance of the PFC circuit, and while holding the battery substantially connected to neutral. In a first embodiment, the circuit comprises a simple combination of four diodes and a pair of high pass capacitors arranged so that in both power line and battery supply modes the battery is balanced around neutral. In a second, preferred embodiment, one terminal of the battery is connected directly to neutral.

Abstract: A drive circuit for use in UPS and like devices, designed to derive high-level switching signals from low-level logic signals. The drive circuit has an input circuit which drives the primary of an air-core transformer, the input drive circuit having an oscillator with a resonant circuit producing a carrier at a carrier frequency, the resonant circuit including the primary of the transformer and a coupling circuit for coupling the logic signals to the oscillator so as to modulate the carrier signal. The use of the resonant circuit enables generation of sufficient magnetization current for the low-cost transformer while reducing the current drive required of the input drive circuit, thereby enabling a reduced cost gate drive circuit.

Abstract: A UPS device adapted for parallel connection to a load along with one or more other UPS devices, having circuitry for sharing of the load, including load harmonics. A feedback network has an error signal circuit which generates an error signal representative of the difference between the actual current provided by the device and the designated share of current it should provide. The error signal is transformed by a value representative of the effective output impedance of the UPS inverter, whereby the inverter is controlled to share the fundamental of the load current as well as the harmonics.

Abstract: An UPS apparatus with a back-up battery and successively coupled rectifier, inverter and output filter circuits, having an improved battery charging circuit. The charging circuit has a transformer with its primary winding being part of the output filter, and its secondary winding driving a second rectifier circuit which produces the charging current. The charging circuit contains an impedance preferably connected between the transformer secondary winding and the second rectifier circuit, for capturing only a high frequency portion of the signal from the inverter stage, thereby enabling the utilization of smaller charger circuit elements.

Abstract: A voltage source having a current feedback control loop for enhanced source impedance control of the output of the voltage source. Current feedback is used for a voltage-source amplifier wherein the source impedance is increased/decreased and/or reshaped by the voltage source amplifier's closed-loop gain and the additional current feedback. In particular, the enhanced source impedance control is accomplished through feedback of the output current of the voltage source to an analog error amplifier at an input to the voltage control loop. The output impedance Z.sub.desired is then adjusted in accordance with the equation Z.sub.desired =Z.sub.inv1 {1+G(s) H(s)}, where G(s) is the voltage source amplifier's closed-loop transfer function, H(s) is the transfer function of the output current feedback circuit and Z.sub.inv1 is the original source impedance of the voltage controlled voltage amplifier.

Abstract: The catalytic combination of a phosphite ester and a phenol sulfide is disclosed. The catalyst combination accelerates and mediates the esterification reaction of rosin with a polyhydric alcohol, resulting in esterified rosins having numerous advantageous characteristics and particular utility as tackifiers in hot melt adhesives.

Abstract: Polyhydric alcohol rosin esters which had been modified with an aromatic dibasic acid such that the softening point of the acid-modified polyhydric alcohol rosin ester is higher than that of a comparable unmodified polyhydric alcohol rosin ester are used as tackifiers in hot melt adhesive compositions. The hot melt adhesives compositions which utilize the acid-modified rosin ester tackifiers contain at least one of an ethylenic copolymer and a styrenic block copolymer, at least one of a wax and an oil, and the acid-modified polyhydric alcohol rosin ester tackifier. The hot melt adhesive compositions may be used as, for example, hot melt carton and package sealing adhesives, sealants, bookbinding adhesives, assembly adhesives, and are useful for the assembly of disposable articles using multiline construction techniques wherein at least one polyethylene or polypropylene substrate is bonded to at least one tissue, non-woven, polyethylene or polypropylene substrate.

Abstract: Method and apparatus for providing protected power to a computer. A computer monitors the terminal voltage and/or current of a battery supplying power to the computer and uses this information or data to determine when, in the event of failure of the AC utility normally supplying power to the computer, to initiate a pre-programmed automatic shutdown of the computer. The determination is based upon the estimated remaining charge of the battery and the total time required to close all active programs in an orderly fashion; thus allowing the computer to be restarted in a well-defined state.

Abstract: This invention relates to a method for treating polymerized rosin to decrease its tendency to oxidize comprising heating the polymerized rosin to an elevated temperature in the presence of an effective amount of one or more disproportionating agents. This invention also relates to the novel products of such disproportionation treatments.

Abstract: Improved rosin ester compositions are provided having diminished tendency toward hazing concomitant with good viscosity stability when employed in adhesive systems such as hot melt adhesive systems. Addition of zinc composition to rosin ester formulations in an effective amount serves to secure these improvements. Zinc oxide, zinc hydroxide and zinc salts of organic acids are suitable for employment with zinc resinates being preferred in accordance with the practice of certain embodiments.

Abstract: An uninterrupted power supply (UPS) system is provided with a power factor correction circuit. The UPS system includes a rectifier having input terminals for connection to an AC utility power source and output terminals. The power factor correction circuit is operatively connected to the input and output terminals of the rectifier to cause the UPS system to exhibit substantially unity power factor to the AC utility power source.

Abstract: A method of improving the color of tall oil rosin esters comprising the sequential steps of (a) recrystallizing a tall oil rosin from a solvent, (b) purifying the crystalline portion by distillation, and (c) esterifying the resultant rosin with a polyol.

Abstract: An uninterrupted power supply (UPS) systems is provided comprising a rectifier circuit, an inverter circuit and a battery boost circuit. One of the input terminals of the rectifier circuit is for connection to the ungrounded conductor of an AC power source and the other input terminal of the rectifier circuit is for connection to the grounded conductor of the AC power source. The UPS has a pair of load terminals for connection to a load. The input terminal of the rectifier circuit for connection to the grounded conductor is connected to one of the pair of load terminals by an electrical conductor whose electrical continuity is maintained from this input terminal to the one of the pair of load terminals without any isolation device such as a 50 or 60 Hz transformer being disposed between the input terminal and the one of the pair of load terminals.

Abstract: Alkali metal and alkaline earth metal salts of hypophosphorous and phosphorous acid are used to catalyze the esterification of rosin with a polyol. The method is an improvement in that reaction time is shortened and the ester product exhibits improved color and thermal stability.

Abstract: A method of preparing polyol esters of rosin comprises carrying out the esterification in an equivalent excess proportion of the rosin reactant. The product of the esterification has novel characteristics including a higher content of fully esterified polyol reactant.

Abstract: Organic esters of hypophosphorous acid are used to catalyze the esterification of rosin with a polyol. The method is an improvement in that reaction time is shortened and the ester product exhibits improved heat stability.

Abstract: Phosphorous acid is used to catalyze the esterification of rosin with a polyol. The method is an improvement in that reaction time is shortened and the ester product exhibits improved color and oxygen stability.