Atlantic Richfield Company

James A Kaehler

Mark R Erickson

An improvement in a system and method of controlling a body to maximize the amount of solar energy received by a collector by moving the body in azimuth and elevation by respective DC motors having connected therewith ring magnets and Hall Effect Devices for signalling the degrees, or steps of rotation. The at least one body may be a collector, per se, or a plurality of heliostats in an array reflecting onto a central collector. A central computer calculates a commanded position for particular time of particular day for the particular location of the body. A microprocessor incorporating respective software and hardware then calculates the position for the heliostat to be in terms of the number of signals from the Hall Effect Device, compares the number of signals from the Hall Effect Device once the motors are energized in, respectively, azimuth and elevation and runs to the commanded position. The software and hardware incorporate means for appropriately starting and stopping the motors at a desired point, such as the zero position of a cycle of alternating current to minimize noise; incorporates means for determining when there is a power failure and shutting down the system to prevent damage upon reapplication of power or the like. By this technique, the body is kept correctly oriented throughout the day using only the time of the day without requiring the usual sensors and feedback apparatus.

Heliostat control employing direct current motor

An improvement in a system and method of controlling heliostat in which the heliostat is operable in azimuth and elevation by respective stepper motors and including the respective steps or means for calculating the position for the heliostat to be at a commanded position, determining the number of steps in azimuth and elevation for each respective motor to get to the commanded position and energizing both the azimuth and elevation stepper motors to run in parallel until predetermined number of steps away from the closest commanded position in azimuth and elevation so that the closest position has been achieved, and thereafter energizing only the remaining motor to bring it to its commanded position. In this way, the heliostat can be started from a stowed position in the morning and operated by a computer means to its commanded position and kept correctly oriented throughout the day using only the time of the day without requiring the usual sensors and feedback apparatus. A computer, or microprocessor, can then control a plurality of many heliostats easily and efficiently throughout the day.

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Littleton, CO, United States of America

James A Kaehler