Analog photovoltaic power circuit

Abstract

The present invention discloses an analog photovoltaic power circuit, comprising: a photovoltaic device group for receiving photo energy to generate an input voltage; a power stage circuit for converting the input voltage to an output voltage; an optimum voltage estimation circuit for receiving a predetermined voltage and estimating an optimum voltage according to a direction of variation of the input voltage and a direction of variation of the power generated by the photovoltaic device group; and an analog comparison and control circuit for comparing the optimum voltage with the input voltage, to thereby control the operation of the power stage circuit.

1 . An analog photovoltaic power circuit, comprising:
 a primary photovoltaic device group for receiving photo energy and generating an input voltage;   a power stage for converting the input voltage to an output voltage;   an optimum voltage point estimation circuit for estimating an optimum voltage point according to a ratio of the open circuit voltage of the primary photovoltaic device group; and   an analog comparison and control circuit for controlling the conversion operation of the power stage according to a comparison between the optimum voltage point estimated by the optimum voltage point estimation circuit and the input voltage.   
     
     
         2 . The analog photovoltaic power circuit as claimed in  claim 1 , wherein the ratio is about 70% to about 90% of the open circuit voltage. 
     
     
         3 . The analog photovoltaic power circuit as claimed in  claim 1 , wherein the optimum voltage point estimation circuit includes a reference photovoltaic device group, and generates the optimum voltage point according to the ratio between the reference photovoltaic device group and the primary photovoltaic device group. 
     
     
         4 . The analog photovoltaic power circuit as claimed in  claim 1 , wherein the optimum voltage point estimation circuit includes a reference photovoltaic device group and a voltage divider circuit electrically connected together, whereby a voltage generated by the reference photovoltaic device group is divided to generate the optimum voltage point. 
     
     
         5 . The analog photovoltaic power circuit as claimed in  claim 1 , wherein the optimum voltage point estimation circuit includes a voltage storage device to store a voltage relating to the open circuit voltage of the primary photovoltaic device group, and estimates the optimum voltage point based on the stored voltage. 
     
     
         6 . The analog photovoltaic power circuit as claimed in  claim 5 , wherein the optimum voltage point estimation circuit further includes a voltage divider circuit to divide the stored voltage. 
     
     
         7 . The analog photovoltaic power circuit as claimed in  claim 6 , wherein a unit gain circuit is provided between the voltage storage device and the voltage divider circuit. 
     
     
         8 . The analog photovoltaic power circuit as claimed in  claim 5 , wherein a diode is provided between the voltage storage device and the voltage divider circuit. 
     
     
         9 . The analog photovoltaic power circuit as claimed in  claim 5 , wherein a switch is provided between the voltage storage device and the voltage divider circuit. 
     
     
         10 . The analog photovoltaic power circuit as claimed in  claim 5 , wherein the voltage storage device periodically refreshes its stored voltage. 
     
     
         11 . The analog photovoltaic power circuit as claimed in  claim 10 , wherein the analog comparison and control circuit receives an enable signal to thereby periodically stop the power stage from receiving the input voltage. 
     
     
         12 . The analog photovoltaic power circuit as claimed in  claim 9 , wherein the switch receives an enable signal to thereby periodically refresh the voltage stored in the voltage storage device. 
     
     
         13 . An analog photovoltaic power circuit, comprising:
 a primary photovoltaic device group for receiving photo energy and generating an input voltage;   a power stage for converting the input voltage to an output voltage;   an optimum voltage point estimation circuit receiving a predetermined voltage and estimating an optimum voltage point according to a direction of variation of the input voltage and a direction of variation of the power generated by the primary photovoltaic device group; and   an analog comparison and control circuit for controlling the conversion operation of the power stage according to a comparison between the optimum voltage point estimated by the optimum voltage point estimation circuit and the input voltage.   
     
     
         14 . The analog photovoltaic power circuit as claimed in  claim 13 , wherein the optimum voltage point estimation circuit includes a variable voltage divider circuit for dividing the predetermined voltage to obtain the optimum voltage point. 
     
     
         15 . The analog photovoltaic power circuit as claimed in  claim 14 , wherein the optimum voltage point estimation circuit includes a direction comparison circuit for comparing the direction of variation of the input voltage and the direction of variation of the power generated by the primary photovoltaic device group, and controlling the variable voltage divider circuit according to the comparison result. 
     
     
         16 . The analog photovoltaic power circuit as claimed in  claim 15 , wherein the direction comparison circuit includes:
 a first high-pass filter receiving the input voltage;   a second high-pass filter receiving a voltage representing the power generated by the primary photovoltaic device group; and   a slope direction comparison circuit comparing the outputs of the first and second high-pass filters.   
     
     
         17 . The analog photovoltaic power circuit as claimed in  claim 16 , wherein the first and second high-pass filters are differential circuits. 
     
     
         18 . The analog photovoltaic power circuit as claimed in  claim 16 , wherein the power stage supplies a voltage to a load, and wherein the voltage representing the power is obtained according to a power supplied to the load. 
     
     
         19 . The analog photovoltaic power circuit as claimed in  claim 16 , wherein the power stage supplies a voltage to a load, and wherein the voltage representing the power is obtained according to a current supplied to the load. 
     
     
         20 . The analog photovoltaic power circuit as claimed in  claim 15 , wherein the power stage supplies a voltage to a load, and wherein the analog photovoltaic power circuit further includes a power meter which measures a power supplied to the load and inputs the measured result to the direction comparison circuit. 
     
     
         21 . The analog photovoltaic power circuit as claimed in  claim 15 , wherein the power stage supplies a voltage to a load, and wherein the analog photovoltaic power circuit further includes a power trend meter which measures a trend of a power supplied to the load and inputs the measured result to the direction comparison circuit. 
     
     
         22 . The analog photovoltaic power circuit as claimed in  claim 21 , wherein the power trend meter estimates the power trend by sensing a heat on a resistor. 
     
     
         23 . The analog photovoltaic power circuit as claimed in  claim 15 , wherein the power stage supplies a voltage to a load, and wherein the analog photovoltaic power circuit further includes a current meter which measures a current flowing to the load and inputs the measured result to the direction comparison circuit. 
     
     
         24 . The analog photovoltaic power circuit as claimed in  claim 13 , wherein the predetermined voltage is a fixed voltage taken from the output of the primary photovoltaic device group or the output of a reference photovoltaic device group. 
     
     
         25 . An analog photovoltaic power circuit, comprising:
 a photovoltaic device group for receiving photo energy and generating an input voltage, the input voltage corresponding to an input current;   a power stage for converting the input voltage to an output voltage;   an optimum voltage point estimation circuit for receiving a predetermined voltage and estimating the optimum voltage point according to a direction of variation of the input current and a direction of variation of the power generated by the primary photovoltaic device group; and   an analog comparison and control circuit for controlling the conversion operation of the power stage according to a comparison between the optimum voltage point estimated by the optimum voltage point estimation circuit and the input voltage.   
     
     
         26 . The analog photovoltaic power circuit as claimed in  claim 25 , wherein the optimum voltage point estimation circuit includes a variable voltage divider circuit for dividing the predetermined voltage to obtain the optimum voltage point. 
     
     
         27 . The analog photovoltaic power circuit as claimed in  claim 26 , wherein the optimum voltage point estimation circuit includes a direction comparison circuit for comparing the direction of variation of the input current and the direction of variation of the power generated by the primary photovoltaic device group, and controlling the variable voltage divider circuit according to the comparison result. 
     
     
         28 . The analog photovoltaic power circuit as claimed in  claim 27 , wherein the direction comparison circuit includes:
 a first high-pass filter receiving a voltage representing the input current;   a second high-pass filter receiving a voltage representing the power generated by the primary photovoltaic device group; and   a slope direction comparison circuit comparing the outputs of the first and second high-pass filters.   
     
     
         29 . The analog photovoltaic power circuit as claimed in  claim 28 , wherein the first and second high-pass filters are differential circuits. 
     
     
         30 . The analog photovoltaic power circuit as claimed in  claim 28 , wherein the power stage supplies a voltage to a load, and wherein the voltage representing the power is obtained according to a power supplied to the load. 
     
     
         31 . The analog photovoltaic power circuit as claimed in  claim 28 , wherein the power stage supplies a voltage to a load, and wherein the voltage representing the power is obtained according to a current supplied to the load. 
     
     
         32 . The analog photovoltaic power circuit as claimed in claim  27 , wherein the power stage supplies a voltage to a load, and wherein the analog photovoltaic power circuit further includes a power meter which measures a power supplied to the load and inputs the measured result to the direction comparison circuit. 
     
     
         33 . The analog photovoltaic power circuit as claimed in  claim 27 , wherein the power stage supplies a voltage to a load, and wherein the analog photovoltaic power circuit further includes a power trend meter which measures a trend of a power supplied to the load and inputs the measured result to the direction comparison circuit. 
     
     
         34 . The analog photovoltaic power circuit as claimed in  claim 33 , wherein the power trend meter estimates the power trend by sensing a heat on a resistor. 
     
     
         35 . The analog photovoltaic power circuit as claimed in  claim 27 , wherein the power stage supplies a voltage to a load, and wherein the analog photovoltaic power circuit further includes a current meter which measures a current flowing to the load and inputs the measured result to the direction comparison circuit. 
     
     
         36 . The analog photovoltaic power circuit as claimed in  claim 25 , wherein the predetermined voltage is a fixed voltage taken from the output of the primary photovoltaic device group or the output of a reference photovoltaic device group. 
     
     
         37 . A method for extracting energy from a photovoltaic device group, comprising the steps of:
 providing a reference voltage of about 70% to about 90% of an open circuit voltage of the photovoltaic device group;   comparing an output voltage of the photovoltaic device group with the reference voltage, to control the output voltage of the photovoltaic device group substantially at the reference voltage; and   extracting energy from the photovoltaic device.   
     
     
         38 . The method as claimed in  claim 37 , wherein the step of providing a reference voltage includes: providing a reference photovoltaic device group which generates voltage of about 70% to about 90% of the photovoltaic device group. 
     
     
         39 . The method as claimed in  claim 37 , wherein the step of providing a reference voltage includes: providing a reference photovoltaic device group; and dividing the voltage generated by the reference photovoltaic device group to obtain the reference voltage. 
     
     
         40 . The method as claimed in  claim 37 , wherein the step of providing a reference voltage includes: storing a voltage relating to the open circuit voltage of the photovoltaic device group; and dividing the voltage relating to the open circuit voltage to obtain the reference voltage. 
     
     
         41 . A method for calculating an optimum voltage point of a photovoltaic device group, comprising the steps of:
 providing a predetermined initial value of a reference voltage;   estimating a direction of variation of the output voltage of the photovoltaic device group;   estimating a direction of variation of the output power of the photovoltaic device group;   comparing the two directions, and increasing the reference voltage when both directions are the same, and decreasing the reference voltage when both directions are opposite; and   using the adjusted reference voltage as the optimum voltage point.   
     
     
         42 . The method of  claim 41 , further comprising the steps of:
 comparing the output voltage of the photovoltaic device group with the optimum voltage point, to control the output voltage of the photovoltaic device group substantially at the reference voltage; and   extracting energy from the photovoltaic device.   
     
     
         43 . The method of  claim 41 , wherein the predetermined initial value of a reference voltage is a division of a fixed voltage, or a division of the output voltage of the photovoltaic device group, or a division of the output voltage of a reference photovoltaic device group. 
     
     
         44 . A method for calculating an optimum voltage point of a photovoltaic device group, comprising the steps of:
 providing a predetermined initial value of a reference voltage;   estimating a direction of variation of the output current of the photovoltaic device group;   estimating a direction of variation of the output power of the photovoltaic device group;   comparing the two directions, and decreasing the reference voltage when both directions are the same, and increasing the reference voltage when both directions are opposite; and   using the adjusted reference voltage as the optimum voltage point.   
     
     
         45 . The method of  claim 44 , further comprising the steps of:
 comparing the output voltage of the photovoltaic device group with the optimum voltage point, to control the output voltage of the photovoltaic device group substantially at the reference voltage; and   extracting energy from the photovoltaic device.   
     
     
         46 . The method of  claim 44 , wherein the predetermined initial value of a reference voltage is a division of a fixed voltage, or a division of the output voltage of the photovoltaic device group, or a division of the output voltage of a reference photovoltaic device group.