Maximum power point tracking system for the solar-supercapacitor power device and method using same

Abstract

A maximum power point tracking system, named flash supercapacitor-solar power device, and method for a solar power system, which mainly adds a pulse-power supercapacitor for being operated in a dynamic equilibrium are disclosed. The duty ratio D is changed and the voltage variance of the supercapacitor is observed to determine the next adjusting direction of the duty ratio D of the DC/DC converter. In the present invention, only a voltage value of the supercapacitor is needed to be monitored and no current-detection is needed. The output power of the solar power system can be actually estimated. The maximum power is traced in an oscillatory way. Therefore, the operation process of the perturbation and observation method, which is generally implemented currently, is simplified. By utilizing the steady-state equilibrium of the supercapacitor, only the voltage of the supercapacitor needs to be detected, and there is no need to measure and calculate the voltage and current values. The system is simple and easily accessible, which is a maximum power point tracking system and method with high efficiency for a solar power system.

1 . A maximum power tracking point method applied to an solar power system comprising the steps of adding an pulse-power supercapacitor. operated in a dynamic equilibrium; changing a duty ratio of a DC/DC converter; and observing a voltage variance of said supercapacitor for determining a next adjusting manner of said duty ratio of said DC/DC converter, wherein only a voltage value of said supercapacitor is needed to be monitored and no current-detection is needed for calculating an output power of said solar power system, and tracking a maximum power point in an oscillatory way. 
     
     
         2 . The maximum power tracking point method of  claim 1 , comprising the following steps of:
 (a) detecting an original voltage value of said pulse-power supercapacitor;   (b) when said voltage value of said pulse-power supercapacitor exceeds a pre-set value, activating a maximum power point tracking system;   (c) adjusting said duty ratio of said DC/DC converter;   (d) detecting a new voltage value of said pulse-power supercapacitor;   (e) comparing said original and new voltage values of said pulse-power supercapacitor;   (f) in case that said new voltage value is higher than said first voltage value, adjusting said duty ratio of said DC/DC converter in a trend toward an original variation direction of said duty ratio;   (g) in case that said second voltage value is lower than said original voltage value, adjusting said duty ratio of said DC/DC converter in a trend reverse to said original variation direction of said duty ratio; and   (h) repeating said steps (a)-(g) in sequence.   
     
     
         3 . The maximum power tracking point method of  claim 1 , wherein said pulse-power supercapacitor is selected from various high energy-density and high power-density supercapacitors, ruthenium dioxide supercapacitors, carbon supercapacitors, metal oxide supercapacitors, polymer supercapacitors, gold capacitors, and aluminum electrolytic capacitors having high capacities. 
     
     
         4 . The maximum power tracking point of  claim 1 , wherein said DC/DC converter is a step-up converter, a step-down converter, a step-up/step-down converter, or any other similar converter. 
     
     
         5 . The maximum power tracking point method of  claim 1 , wherein solar energy inputted into/outputted from said pulse-power supercapacitor is in a dynamic equilibrium state, and said solar energy is transferred to said DC/DC converter; an output voltage of said photovoltaic panel and an input energy of said pulse-power supercapacitor are changed by adjusting said duty ratio of said DC/DC converter; the voltage value of said pulse-power supercapacitor serves as an energy characteristic of said pulse-power supercapacitor and is measured and compared at different times for observing an output energy change trend of said photovoltaic panel, so as to track a maximum power point of said solar power system. 
     
     
         6 . The maximum power tracking point method of  claim 1 , wherein when an intensity of a sunshine is strong, said pulse-power supercapacitor undergoes a maximum power point tracking; when said intensity of said sunshine is weak or it is in a worse weather that only a weak solar energy generates, said supercapacitor accumulates weak electric energy transferred from said weak solar energy and charges a accumulator when accumulated energy become higher, wherein said pulse-power supercapacitor serves as an energy accumulator of said weak electric energy. 
     
     
         7 . The maximum power tracking point method of  claim 6 , wherein a charging mode of said accumulator is based on a detected voltage of said accumulator, undergoing a pulse charging in an initial period, a full-speed charging in a middle period, and a pulse charging in an ending period, wherein in said full-speed charging, said electric energy generated by solar energy system is totally charged into said accumulator. 
     
     
         8 . The maximum power tracking point method of  claim 6 , wherein said charging mode can be replaced by a normal charging mode such as a constant current charging, a constant voltage charging, a constant power, a two/three stages charging, or a speed charging. 
     
     
         9 . The maximum power tracking point method of  claim 6 , wherein said steps of charging said accumulator include an intelligent-adjustable discharging step in which an output of said accumulator is set in an adjustable constant current, an adjustable constant voltage or an adjustable constant power for driving a load. 
     
     
         10 . The maximum power tracking point method of  claim 9 , wherein in said discharging mode, said accumulator is controlled by a logic control circuit through a DC/DC step-up/step-down converter to keep a constant output which is not influenced when the voltage of said accumulator is reduced and said constant output can be raised to strengthen power outputted to said load. 
     
     
         11 . The maximum power tracking point method of  claim 10 , wherein when said accumulator is going to be full-charged by said discharging step and there is still solar energy converted, said pulse-power supercapacitor will serve as a second accumulator for outputting power to said load without passing through said accumulator. 
     
     
         12 . A maximum power tracking point method applied to a solar power system comprising:
 a photovoltaic panel;   a pulse-power supercapacitor, which is a dynamic-equilibrium energy-storing device for receiving energy outputted from said photovoltaic panel and outputting electric energy to a DC/DC converter;   said DC/DC converter, which is capable of adjusting an output voltage and energy of said solar power system; and a pulse width modulation driver for delivering pulse signal to control said DC/DC converter.   
     
     
         13 . The maximum power tracking point method of  claim 12 , wherein said photovoltaic panel is constructed by a plurality of photovoltaic units connected in serial/parallel as needed; and
 wherein said DC/DC converter is a step-up converter a step-down converter, a step-up/step-down converter or any other similar converter.   
     
     
         14 . (canceled) 
     
     
         15 . The maximum power tracking point method of  claim 12 , wherein said pulse-power supercapacitor is electrically connected to a logic control circuit which is electrically connected to a voltage/circuit guard circuit. 
     
     
         16 . The power tracking method of  claim 15 , wherein said voltage/current circuit is connected to an accumulator electrically connected to a load for preventing said load from a damage caused by over charging/discharging of said accumulator. 
     
     
         17 . The power tracking method of  claim 16 , wherein said load is selected from an LED array, a lamp, a mechanical device, a monitoring equipment, a detecting apparatus, and a signal-communicator, and said load is further connected to a current detector for detecting a current on said load. 
     
     
         18 . The maximum power tracking point power tracking method of  claim 16 , wherein said accumulator is a Lead-acid storage battery, or a rechargeable battery selected from a Nickel-Cadmium battery, a Nickel-Metal Hydride battery, a Lithium-ion battery, a Lithium-polymer battery, and a Lead-acid storage battery. 
     
     
         19 . The maximum power tracking point method of  claim 1 , wherein said photovoltaic panel is connected to a first electric switch, said first electric switch is electrically connected to said DC/DC converter, and said DC/DC converter is electrically connected to a second electric switch. 
     
     
         20 . The maximum power tracking point method of  claim 19 , wherein said first and second electric switches are semiconductor electric switches which include higher operational speed than analog switches; and
 wherein said logic control circuit is a microcontroller or a microcontroller-like controller.   
     
     
         21 . (canceled) 
     
     
         22 . The maximum power tracking point method of  claim 15 , further comprising a current detector for detecting a current of said load and generating a detecting signal transmitted to said logic control circuit through said voltage/current guard circuit for controlling a current outputted from a battery to said load.