Patent ID: 6469487
Filing Date: 2002-10-22
Classification: F25B,F25D,H01L,H02J,H02S,Y02E,Y10S

Abstract:
A solar powered apparatus which comprises:a variable speed motor; a power source which converts light into electrical power having a DC voltage; a power bus coupled to the power source and configured to provide electrical power at said DC voltage to the variable speed motor, and a controller coupled to the power bus to detect said DC voltage and coupled to the variable speed motor to provide a speed control signal, wherein the controller determines a time derivative of said DC voltage, wherein the controller increases the motor speed if the derivative of said DC voltage is above a predetermined threshold, and wherein the controller decreases the motor speed if the derivative of said DC voltage is below the predetermined threshold, and wherein the controller is further configured to adjust the speed control signal to maximize usage of the electrical power from the power source wherein the controller determines a second-order time derivative of said DC voltage, and wherein the controller increases the motor speed if the second-order derivative is above a predetermined threshold, and wherein the controller decreases the motor speed if the second-order derivative is below the predetermined threshold, wherein the controller is configured to adjust the speed control signal to maximize usage of the electrical power from the power source.