Applied Power Inc.

Display Laboratories, Inc.

Gregory A Kern

James R Webb

A control system is provided for positioning between a power source, such as a distributed generator, and a utility or utility grid to control the injection of dc current and even harmonics into the utility or utility grid. In one embodiment, the control system is particularly suited for grid-tied operation and includes a power converter for acting as an ac current source by converting power received from the power source to ac current for transmittal to the utility. The control system further includes a voltage transformer between the power converter and the utility connection to block dc current and isolate the power source from the utility. A feedback control loop is included in the control system to measure, with a pair of current transformers, dc current and even harmonics in the current flowing into (power converter side) and out (utility side) of the voltage transformer. A signal combiner is used to combine the outputs of the two current transformers such that its output to a harmonic analyzer of the feedback control loop represents the load current of the voltage transformer. The harmonic analyzer determines the magnitude and phase of the second harmonic of this load current and transmits this as output to a controller of the feedback control loop. The controller creates a control signal that it transmits to a reference device connected to, or integrated with, the power converter which creates a reference signal having a dc offset that functions to substantially zero out the linearized second harmonic magnitude. The reference signal is used to control the operation and output of the power converter to substantially eliminate dc current injection into the voltage transformer which in turn effectively limits the amplitude of even harmonics in the current supplied to the utility.

DC injection and even harmonics control system

A system for delivering power to a battery and to a load includes a power source that supplies energy to the battery and the load. The battery can be charged by the power source and used to supply energy or power to the load when the power source is unable to provide sufficient energy and power to the load. The system reduces injection of DC current into the load and, as a result, extends the operation life of the load, particularly if the load is an AC lighting or lamp system. The system operates the load in an optimal manner such that battery storage is maintained at near full charge, yet the lighting load operates for a maximum number of hours per night. The benefit of the system is to prevent early failure of either the lighting load or the battery.

Method and apparatus for providing energy to a lighting system

A system for transforming coordinate systems in an automated video monitor alignment system includes a camera and computer to capture an image of the display bezel surrounding the cathode ray tube and of the image displayed on the CRT. Three dimensional models of the CRT tube and display bezel are used to compute and compensate for camera perspective. Camera pixel data can then be transformed to `flat plane` coordinates. When the relative orientation of the camera and CRT are corrected for, the effects of parallax can be eliminated, allowing more accurate inspection, measurement, and lower cost fixturing on the production line. Thus, an accurate coordinate transformation from a camera-referenced coordinate system to a monitor-referenced coordinate system is made.

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Louisville, CO, United States of America

Gregory A Kern