Abstract: A photovoltaic power plant design is disclosed where a two-tier DC power collection method is used in concert with specific array field geometries and equipment locations to minimize system wiring costs and/or resistive wiring losses.

Abstract: A device and method is disclosed for providing electrical grid-tied power converter anti-islanding protection, which is autonomous to the operation of the power converter. The device can protect any number of paralleled power converters and can independently detect an islanding condition. The method involves actively perturbing the electrical grid at a common point of coupling between converter and grid, observing the effect of the perturbation, comparing the perturbed and non-perturbed grid characteristics and disconnecting the converter from the grid if an island is indicated. Perturbation is accomplished by switching a reactive load or loads onto the grid or by changing a transformer tap. The invention is targeted for solar photovoltaic applications where a number of distributed power converters are used.

Abstract: A power converter design is disclosed with a novel approach to thermal management which enhances the performance and significantly reduces the cost of the converter compared to prior art power converters. The invention minimizes the heating of one power component by another within the power converter and therefore enables the power converter to work at higher power levels. Essentially, the power converter uses a heatsink having a high length to width ratio, a linear array of power components thermally coupled to the heatsink parallel to the long axis of the heatsink and a heat removal system which produces the highest cross sectional thermal flux perpendicular to said long axis. In addition, a number of ancillary thermal management techniques are used to significantly enhance the value of this basic approach.

Abstract: An electrical contactor with high DC and AC interrupt capability is disclosed. The invention is intended for applications where load break capability is only required under abnormal operating conditions. Under overload conditions, an alternate path is automatically provided through a sacrificial fuse to divert current from opening, or open and arcing, contacts such that the fuse interrupts the fault current and not the contacts. The current rating of the sacrificial fuse may be orders of magnitude less than the normal carry current of the contactor. The contactor provides a one-time load break function that is renewable by the replacement of a fuse.

Abstract: The invention is an apparatus and method for safely disconnecting a bipolar photovoltaic array from earth ground under normal static operating conditions. The invention senses the voltage to earth on all three terminals of a bipolar photovoltaic array and uses a set of operable contacts to selectively couple or uncouple the DC neutral point of the array (the center tap) to earth ground. When all three terminals of the bipolar array are within the rated voltage capability of the photovoltaic array the DC neutral point is allowed to float.

Abstract: A power converter design is disclosed with a novel approach to thermal management which enhances the performance and significantly reduces the cost of the converter compared to prior art power converters. The invention minimizes the heating of one power component by another within the power converter and therefore enables the power converter to work at higher power levels. Essentially, the power converter uses a heatsink having a high length to width ratio, a linear array of power components thermally coupled to the heatsink parallel to the long axis of the heatsink and a heat removal system which produces the highest cross sectional thermal flux perpendicular to said long axis. In addition, a number of ancillary thermal management techniques are used to significantly enhance the value of this basic approach. A specific circuit design for the power converter is not disclosed or discussed as the invention can be applied to any number of power converter electrical topologies.

Abstract: The invention is an electrical power conversion topology. The preferred embodiment is as a three-phase, on-line Uninterruptible Power Supply (UPS). The desired AC output voltage waveform is formed on each output line or phase of the UPS, using pulse modulation techniques and a smoothing output filter inductor. A semiconductor switching matrix is used to switch the power converter side of each output filter inductor between three voltage potentials, a positive battery potential, a negative battery potential and a third intermediate and varying AC potential synchronized with the desired output voltage. The invention potentially provides the same performance as that of a multi-level inverter topology approaching an infinite number of DC levels.

Abstract: A device and method is disclosed for providing anti-islanding protection for an electrical grid-tied power converter, which is autonomous to the operation of the power converter. The device can protect any number of paralleled power converters and can independently determine if an islanding condition exists. The method involves actively perturbing the electrical grid at a common point of coupling between converter and grid, observing the effect of the perturbation, comparing the perturbed and non-perturbed grid characteristics and disconnecting the converter from the grid if a run-on or islanding condition is indicated. Perturbation is accomplished switching a reactive load or loads onto the grid or by changing a transformer tap connection at the point of common coupling. The invention is targeted for use in solar photovoltaic power plants which have a number of distributed DC-to-AC power converters.

Abstract: An improved method of collecting DC power in solar photovoltaic systems is disclosed where series string overcurrent protection is provided at distributed series string terminus locations and a tap connection is made to higher current conductors carrying the combined currents of a number of series strings. A number of related string combiner methods and embodiments are disclosed.

Abstract: A new type of the passive non-dissipative snubber with a single saturable reactor improves the performance of the boost converter used as a front-end active Power Factor Correction (PFC) in two critical areas: excess voltage stresses caused by high voltage spikes on input high voltage switching transistor of the boost converter is eliminated and EMI noise is much reduced. The high voltage spike energy instead of being dissipated as in a dissipative snubber circuits is recovered resulting in increased conversion efficiency. High voltage spike elimination also allows use of lower voltage rated devices with lower ON resistance, hence further increasing the efficiency of the PFC boost converter.

Abstract: The Voltage Sense Method is introduced and a number of its implementations using Voltage Sense Circuit are demonstrated to solve problems associated with the start-up of parallel switching converters, each converter having output synchronous rectifiers or more general Current Bi-directional Switches: prevention of the excessive reverse current, elimination of the excess voltage stress of the input switches and elimination of the voltage overshoot in the common output voltage. The Voltage Sense circuit added to each converter generates a Simulated Output Voltage, which predicts how would the output voltage of each particular unit rise during the start-up with enabled synchronous rectifiers if that particular unit were to operate alone.

Abstract: A surge protector for portable personal computers, or notebooks, of the shunting type, employs two differently rated metal oxide varistors in a manner enabling operation with several differently rated AC power services the surge protector is designed to provide an optimum effective clamping voltage with a low let-through voltage.

Abstract: A discontinuous conduction mode (DCM) electronic ballast topology is presented which drives the lamp with line frequency voltage and current, just like a magnetic ballast. However, compared to magnetic ballast, its weight is substantially reduced due to operation at high switching frequency (40 kHz in the experimental prototype). The topology also ensures unity power factor at the input and stable lamp operation at the output.

Abstract: The isolated, multiple output, switching converter is created with a number of unique performance characteristics. The converter operates in continuous inductor current mode (CICM) of operation for all load currents from no load to full load on all outputs despite the presence of simple rectifier diodes only on the converter secondary sides. The regulation of output voltages on all outputs against the changes of the input voltage is provided by use of a simple open-loop control circuit connected to the primary side and thus eliminating the need for isolation in the control circuit. The regulation against the load current changes in the single output case is also provided on the primary side by a load current sensing circuit. An additional benefit of the switching converter is in the elimination of the losses and voltage overshoots associated with the leakage inductance of the isolation transformer when operated as pulse width modulated (PWM) converter.

Abstract: In a dc-to-dc converter, input and output inductors loosely coupled and isolation transformer windings closely coupled are implemented on a UI magnetic core in such a manner as to satisfy a zero-ripple condition k.sub.1 =n of current in the output inductor, where n is a turns ratio of the loosely coupled input and output inductors, and both inductors are chosen to have the same number of turns, and that number is an integer such that the value of the coupling coefficient k.sub.1 required to satisfy the zero-ripple condition is one achieved by modeling of core leakages instead of by adjusting the turns ratio n, thus making it feasible to implement the coupled inductors, and the transformer windings as well, in a single UI core and modeling the core losses by configuring the core.

Abstract: A high density cell stack is provided utilizing a flexible cathode material having at least four sections in the form of a rectangle and flexible anode materials folded over each other at right angles. A suitable anode material is lithium and a suitable cathode material is manganese dioxide. The disclosed cell stacks are rapidly manufactured to provide high density cells with good mechanical stability and good stability against shorting.

Abstract: A high density cell stack is provided utilizing strips of flexible cathode material and flexible anode materials folded over each other at right angles. A suitable anode material is lithium and a suitable cathode material is manganese dioxide. The disclosed cell stacks are rapidly manufactured to provide high density cells with good mechanical stability and good stability against shorting.

Abstract: An isolated switching dc-to-dc converter is provided with a novel open-loop input voltage regulation on the primary side and the full regulation and independent protection of each of multiple outputs on the secondary side using an auxiliary circuit comprising a current bidirectional switch Q.sub.a and a capacitor C.sub.a on the primary side in a series circuit connected in parallel with a main current bidirectional switch Q to assure a continuous conduction mode for operation of the primary boost-like converter, and consequently preserves the simplicity of open-loop input voltage regulation for all loads from no load to full load. The auxiliary switch Q.sub.a is very efficient with only a fraction (5% or less) of the losses of the main active switch Q. The ideal dynamic response approaching theoretical limits is achieved for both line and load transients together with a high efficiency (85%) and record power density (20 W per cubic inch) for multiple output converters.

Abstract: A high density cell stack is provided utilizing strips of flexible cathode material and flexible anode materials folded over each other at right angles. A suitable anode material is lithium and a suitable cathode material is manganese dioxide. The disclosed cell stacks are rapidly manufactured to provide high density cells with good mechanical stability and good stability against shorting.

Abstract: A method and apparatus for monitoring the condition of a plurality of electrochemical cells and controlling the output of said cells upon detection of a cell having a lower capacity than the others.