US5747967A
Expired / Lapsed
US
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Apparatus and method for maximizing power delivered by a photovoltaic array
Assignee: Midwest Research Institute
•
Filing: 1996-02-22
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Granted: 1998-05-05
•
Expires: 2016-02-22
Abstract
Abstract A method and apparatus for maximizing the electric power output of a photovoltaic array connected to a battery where the voltage across the photovoltaic array is adjusted through a range of voltages to find the voltage across the photovoltaic array that maximizes the electric power generated by the photovoltaic array and then is held constant for a period of time. After the period of time has elapsed, the electric voltage across the photovoltaic array is again adjusted through a range of voltages and the process is repeated. The electric energy and the electric power generated by the photovoltaic array is delivered to the battery which stores the electric energy and the electric power for later delivery to a load.
Inventors
- 👤 Eduard Muljadi
- 👤 Roger W. Taylor
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 07:01
CPC Classifications
H; H01; H01M; H01M10/00; H01M10/42; H01M10/46; H01M10/465; H02; H02J; H02J7/00; H02J7/34; H02J7/35; Y; Y02; Y02E; Y02E10/00; Y02E10/50; Y02E10/56; Y02E60/00; Y02E60/10; Y10; Y10S; Y10S136/00; Y10S136/291; Y10S136/293
Claims Analysis
Total Claims: 54
Claim 1
Independent Claim
377 words
Apparatus for controlling electric power that is generated by a photovoltaic cell and delivered to a battery that has positive and negative terminals, wherein the photovoltaic cell also has positive and negative terminals and the photovoltaic cell generates an electric voltage between its positive and negative terminals and a corresponding electric current flowing out of its positive terminal when radiation is incident on the photovoltaic cell, and wherein the battery has an electric voltage between its positive and negative terminals that is approximately constant during a predetermined time period, comprising: converter means electrically connected to the photovoltaic cell and to the battery for electrically connecting and disconnecting the photovoltaic cell to and from the battery, for controlling and varying the electric voltage generated between the positive and negative terminals of the photovoltaic cell, and for generating and controlling an electric current that flows through the battery such that the electric power generated by the photovoltaic cell is at a maximum during the time period when the electric current flowing through the battery is at a maximum during the time period, said converter means including a switch means for controlling when said converter means electrically connects the photovoltaic cell to the battery and when said converter means electrically disconnects the photovoltaic cell from the battery, wherein said switch means has a first state of operation and a second state of operation such that when said switch means is operating in its first state of operation the photovoltaic cell is electrically connected to the battery and when said switch means is operating in its second state of operation the photovoltaic cell is electrically disconnected from the battery; peak current determining means coupled to the battery for determining when the electric current flowing through the battery is at a maximum and for generating an electric signal when the electric current flowing through the battery is at a maximum; and switch control means electrically connected to said switch means and to said peak current determining means for controlling when said switch means is operating in said first state of operation and when said switch means is operating in said second state of operation, wherein said switch control means is responsive to said electric signal generated by said peak current determining means.
Claim 2
Dependent Claim
377 words
Apparatus for controlling electric power that is generated by a photovoltaic cell and delivered to a battery that has positive and negative terminals, wherein the photovoltaic cell also has positive and negative terminals and the photovoltaic cell generates an electric voltage between its positive and negative terminals and a corresponding electric current flowing out of its positive terminal when radiation is incident on the photovoltaic cell, and wherein the battery has an electric voltage between its positive and negative terminals that is approximately constant during a predetermined time period, comprising: converter means electrically connected to the photovoltaic cell and to the battery for electrically connecting and disconnecting the photovoltaic cell to and from the battery, for controlling and varying the electric voltage generated between the positive and negative terminals of the photovoltaic cell, and for generating and controlling an electric current that flows through the battery such that the electric power generated by the photovoltaic cell is at a maximum during the time period when the electric current flowing through the battery is at a maximum during the time period, said converter means including a switch means for controlling when said converter means electrically connects the photovoltaic cell to the battery and when said converter means electrically disconnects the photovoltaic cell from the battery, wherein said switch means has a first state of operation and a second state of operation such that when said switch means is operating in its first state of operation the photovoltaic cell is electrically connected to the battery and when said switch means is operating in its second state of operation the photovoltaic cell is electrically disconnected from the battery; peak current determining means coupled to the battery for determining when the electric current flowing through the battery is at a maximum and for generating an electric signal when the electric current flowing through the battery is at a maximum; and switch control means electrically connected to said switch means and to said peak current determining means for controlling when said switch means is operating in said first state of operation and when said switch means is operating in said second state of operation, wherein said switch control means is responsive to said electric signal generated by said peak current determining means.
Claim 3
Dependent Claim
115 words
The apparatus of claim 1, wherein said switch control means includes first electric voltage waveform generator means for generating a triangle electric voltage waveform during the time period, second electric voltage waveform generator means for generating a ramp-shaped electric voltage waveform during a first portion of the time period and a fixed voltage waveform during a second portion of the time period, and comparator means for comparing said electric voltage waveforms produced by said first and second electric voltage waveform generator means and for creating an electric voltage waveform having a varying duty cycle during said first portion of the time period and a fixed duty cycle during said second portion of the time period.
Claim 4
Dependent Claim
27 words
The apparatus of claim 2, wherein the total of said first and second portions of the time period is less than or equal to the time period.
Claim 5
Dependent Claim
24 words
The apparatus of claim 3, wherein the total of said first and second portions of the time period is equal to the time period.
Claim 6
Dependent Claim
28 words
The apparatus of claim 2, wherein said triangle electric voltage waveform produced by said first voltage waveform generator means has a frequency of approximately ten thousand (10,000) hertz.
Claim 7
Dependent Claim
35 words
The apparatus of claim 2, wherein said ramp-shaped electric voltage waveform produced by said second voltage waveform generator means during said first portion of the time period has a frequency of approximately twenty (20) hertz.
Claim 8
Dependent Claim
70 words
The apparatus of claim 2, wherein said second electric voltage waveform generator means includes a counter means for producing a plurality of electric voltage signals digitally representing a binary number and a digital-to-analog converter means for converting said digitally represented binary number produced by said counter means on said plurality of electric voltage signals to a single voltage signal having an amplitude linearly related to said digitally represented binary number.
Claim 9
Dependent Claim
77 words
The apparatus of claim 7, wherein said second electric voltage waveform generator means further includes latching means electrically disposed between said counter means and said digital-to-analog converter means for allowing said plurality of electric voltage signals produced by said counter means to be input signals to said digital-to-analog converter means during said first portion of the time period, and for latching the input signals to said digital-to-analog converter means during said second portion of the time period.
Claim 10
Dependent Claim
34 words
The apparatus of claim 8, wherein said switch control means further includes a clock means for providing an electric signal to said latching means when said first portion of the time period has started.
Claim 11
Dependent Claim
30 words
The apparatus of claim 8, wherein said switch control means sends an electric signal to said peak current determining means when said first portion of the time period has started.
Claim 12
Dependent Claim
36 words
The apparatus of claim 2, wherein said peak current determining means includes a resistor in electrical series with the battery such that all of the electric current flowing through the battery also flows through said resistor.
Claim 13
Dependent Claim
39 words
The apparatus of claim 11, wherein said peak current determining means further includes a capacitor that is electrically discharged prior to said first portion of the time period and electrically charged during said first portion of the time period.
Claim 14
Dependent Claim
36 words
The apparatus of claim 1, wherein said converter means includes a capacitor electrically connected to said positive and negative terminals of the photovoltaic cell such that said capacitor is in electrical parallel with the photovoltaic cell.
Claim 15
Dependent Claim
39 words
The apparatus of claim 1, wherein said switch means has a first electric terminal and a second electric terminal and said second electric terminal of said switch means is electrically connected to said negative terminal of the photovoltaic cell.
Claim 16
Dependent Claim
31 words
The apparatus of claim 14, wherein said converter means includes an inductor electrically connected between the positive terminal of the photovoltaic cell and said first electric terminal of said switch means.
Claim 17
Dependent Claim
82 words
The apparatus of claim 15, including first current flow prevention means for preventing electric current from flowing out of the positive terminal of the battery, wherein said first current flow prevention means has a first electric terminal and a second electric terminal, said second electric terminal of said first current flow prevention means is electrically connected to the positive terminal of the battery, and said second electric terminal of said first current flow prevention means is electrically connected to said converter means.
Claim 18
Dependent Claim
15 words
The apparatus of claim 16, wherein said first current flow prevention means includes a diode.
Claim 19
Dependent Claim
64 words
The apparatus of claim 16, wherein said converter includes a capacitor having a first electric terminal and a second electric terminal wherein said first electric terminal of said capacitor is electrically connected to said first electric terminal of said first current flow prevention means and said first electric terminal of said capacitor is electrically connected to said second electric terminal of said switch means.
Claim 20
Dependent Claim
40 words
The apparatus of claim 18, wherein said converter means includes a second current flow prevention means for preventing electric current from flowing out of said first electric terminal of said capacitor and through said switch means and through said inductor.
Claim 21
Dependent Claim
15 words
The apparatus of claim 19, wherein said second current flow prevention means includes a diode.
Claim 22
Dependent Claim
257 words
Method of controlling electric power generated by a photovoltaic cell and delivered to a battery that has positive and negative terminals, wherein the photovoltaic cell also has positive and negative terminals and the photovoltaic cell generates an electric voltage between its positive and negative terminals and a corresponding electric current flowing out of its positive terminal when radiation is incident on the photovoltaic cell, and wherein the battery has an electric voltage between its positive and negative terminals that is approximately constant during a predetermined time period, comprising the steps of: electrically coupling the photovoltaic cell and the battery such that an electric current flows through the battery, varying the electric voltage generated between the positive and negative terminals of the photovoltaic cell will result in varying of the electric current flowing through the battery, and such that the electric power generated by the photovoltaic cell during the time period is at a maximum when the electric current flowing through the battery during the time period is at a maximum; varying the electric voltage between the positive and negative terminals of the photovoltaic cell during a first portion of the time period; determining when the electric current flowing through the battery is at a maximum during said first portion of the time period; and maintaining the electric voltage between the positive and negative terminals of the photovoltaic cell for a second portion of the time period such that said determined maximum electric current flowing through the battery is maintained during said second portion of the time period.
Claim 23
Dependent Claim
257 words
Method of controlling electric power generated by a photovoltaic cell and delivered to a battery that has positive and negative terminals, wherein the photovoltaic cell also has positive and negative terminals and the photovoltaic cell generates an electric voltage between its positive and negative terminals and a corresponding electric current flowing out of its positive terminal when radiation is incident on the photovoltaic cell, and wherein the battery has an electric voltage between its positive and negative terminals that is approximately constant during a predetermined time period, comprising the steps of: electrically coupling the photovoltaic cell and the battery such that an electric current flows through the battery, varying the electric voltage generated between the positive and negative terminals of the photovoltaic cell will result in varying of the electric current flowing through the battery, and such that the electric power generated by the photovoltaic cell during the time period is at a maximum when the electric current flowing through the battery during the time period is at a maximum; varying the electric voltage between the positive and negative terminals of the photovoltaic cell during a first portion of the time period; determining when the electric current flowing through the battery is at a maximum during said first portion of the time period; and maintaining the electric voltage between the positive and negative terminals of the photovoltaic cell for a second portion of the time period such that said determined maximum electric current flowing through the battery is maintained during said second portion of the time period.
Claim 24
Dependent Claim
23 words
The method of claim 21, wherein said first portion of the time period and said second portion of the time period occur sequentially.
Claim 25
Dependent Claim
27 words
The method of claim 22, wherein the total of said first and second portions of the time period is less than or equal to the time period.
Claim 26
Dependent Claim
24 words
The method of claim 23, wherein the total of said first and second portions of the time period is equal to the time period.
Claim 27
Dependent Claim
25 words
The method of claim 21, including the step of measuring the electric current flowing through the battery during said first portion of the time period.
Claim 28
Dependent Claim
28 words
The method of claim 21, including the step of maintaining approximately a constant electric voltage between the positive and negative terminals of the battery during the time period.
Claim 29
Dependent Claim
29 words
The method of claim 21, wherein the electric current flowing through the battery is linearly related to the electric power generated by the photovoltaic cell during the time period.
Claim 30
Dependent Claim
51 words
The method of claim 21, wherein said step of coupling the photovoltaic cell to the battery includes the steps of electrically connecting a converter to the photovoltaic cell and the battery, wherein said converter has a switch which controls the electrical connection and disconnection of the photovoltaic cell and the battery.
Claim 31
Dependent Claim
52 words
The method of claim 28, including the steps of providing a duty cycle signal to said switch which turns said switch on and off and varying said duty cycle signal during said first portion of the time period and fixing said duty cycle signal during said second portion of the time period.
Claim 32
Dependent Claim
39 words
The method of claim 29, wherein said switch has a first electric terminal and a second electric terminal, and including the step of connecting said second electric terminal of said switch to the negative terminal of the photovoltaic cell.
Claim 33
Dependent Claim
29 words
The method of claim 30, including the step of electrically connecting an inductor between the positive terminal of the photovoltaic cell and said first electric terminal of said switch.
Claim 34
Dependent Claim
35 words
The method of claim 31, including the step of electrically connecting a capacitor to the positive and negative terminals of the photovoltaic cell such that said capacitor is in electric parallel to the photovoltaic cell.
Claim 35
Dependent Claim
34 words
The method of claim 21, including the step of electrically connecting a resistor in series with the battery such that all of the electric current flowing through the battery also flows through said resistor.
Claim 36
Dependent Claim
174 words
Apparatus for optimizing electrical power production by a photovoltaic power source that is electrically connected by an electric circuit to a battery, comprising: a voltage converter positioned in the electric circuit between the photovoltaic power source and the battery with the capability of varying voltage across the photovoltaic power source in response to a firing signal; and a peak current detector connected to the electric circuit and a firing circuit, said peak current detector having a capability to detect when a varying electric current flowing through the battery is at a maximum and to produce a peak current signal when said electric current flowing through the battery is at the maximum, wherein said firing circuit is also connected to said voltage converter and has a capability of producing said firing signal in a variable manner that causes said voltage converter to vary voltage across the photovoltaic power source until said peak current detector produces a peak current signal and, in response to said peak current signal, producing said firing signal in a nonvariable manner.
Claim 37
Dependent Claim
174 words
Apparatus for optimizing electrical power production by a photovoltaic power source that is electrically connected by an electric circuit to a battery, comprising: a voltage converter positioned in the electric circuit between the photovoltaic power source and the battery with the capability of varying voltage across the photovoltaic power source in response to a firing signal; and a peak current detector connected to the electric circuit and a firing circuit, said peak current detector having a capability to detect when a varying electric current flowing through the battery is at a maximum and to produce a peak current signal when said electric current flowing through the battery is at the maximum, wherein said firing circuit is also connected to said voltage converter and has a capability of producing said firing signal in a variable manner that causes said voltage converter to vary voltage across the photovoltaic power source until said peak current detector produces a peak current signal and, in response to said peak current signal, producing said firing signal in a nonvariable manner.
Claim 38
Dependent Claim
60 words
The apparatus of claim 34, including a timing circuit connected to said firing circuit, wherein said timing circuit has a capability of producing timing signals, and wherein said firing circuit is responsive to said timing signals to produce said firing signals in said nonvariable manner for a time period and then to produce said firing signals in said variable manner.
Claim 39
Dependent Claim
95 words
The apparatus of claim 34, wherein said voltage converter includes a boost voltage circuit comprising an inductor positioned between the photovoltaic power source and the battery, a switch that opens and closes a short circuit across said photovoltaic's power source between said photovoltaic power source and said battery, and a diode between said short circuit and said battery, said switch being responsive to said firing signals to open and close said short circuit repetitively at a variable rate when said firing signals are variable and at a nonvariable rate when said firing signals are nonvariable.
Claim 40
Independent Claim
75 words
A method of optimizing power production by a photovoltaic power source that is being used to charge a battery, comprising the steps of: using a boost converter with a variable duty cycle to vary voltage across the photovoltaic power source while monitoring current flow through the battery until maximum current flow through the battery is detected and then maintaining for a period of time whatever duty cycle that existed to produce the maximum current flow.
Claim 41
Independent Claim
75 words
A method of optimizing power production by a photovoltaic power source that is being used to charge a battery, comprising the steps of: using a boost converter with a variable duty cycle to vary voltage across the photovoltaic power source while monitoring current flow through the battery until maximum current flow through the battery is detected and then maintaining for a period of time whatever duty cycle that existed to produce the maximum current flow.
Claim 42
Dependent Claim
51 words
The method of claim 37, including the steps of varying the duty cycle again after the period of time until a subsequent maximum current flow through the battery is detected and then maintaining for a subsequent period of time whatever duty cycle that existed to produce the subsequent maximum current flow.
Claim 43
Independent Claim
72 words
A method of optimizing power production by a photovoltaic power source that is being used to charge a battery, comprising the steps of: varying the voltage across the photovoltaic power source while monitoring current flow through the battery until maximum current flow through the battery is detected and then maintaining for a period of time whatever voltage existed across the photovoltaic power source to produce the maximum current flow through the battery.
Claim 44
Independent Claim
72 words
A method of optimizing power production by a photovoltaic power source that is being used to charge a battery, comprising the steps of: varying the voltage across the photovoltaic power source while monitoring current flow through the battery until maximum current flow through the battery is detected and then maintaining for a period of time whatever voltage existed across the photovoltaic power source to produce the maximum current flow through the battery.
Claim 45
Dependent Claim
374 words
Apparatus for controlling electric power that is generated by a photovoltaic cell and delivered to a battery that has positive and negative terminals, wherein the photovoltaic cell also has positive and negative terminals and the photovoltaic cell generates an electric voltage between its positive and negative terminals and a corresponding electric current flowing out of its positive terminal when radiation is incident on the photovoltaic cell, and wherein the battery has an electric voltage between its positive and negative terminals that is approximately constant during a time period, comprising: converter means electrically connected to the photovoltaic cell and to the battery for electrically connecting and disconnecting the photovoltaic cell to and from the battery, for controlling and varying the electric voltage generated between the positive and negative terminals of the photovoltaic cell, and for controlling an electric current that flows through the battery such that the electric power generated by the photovoltaic cell is at a maximum during the time period when the electric current flowing through the battery is at a maximum during the time period, said converter means including a switch means for controlling when said converter means electrically connects the photovoltaic cell to the battery and when said converter means electrically disconnects the photovoltaic cell from the battery, wherein said switch means has a first state of operation and a second state of operation such that when said switch means is operating in its first state of operation the photovoltaic cell is electrically connected to the battery and when said switch means is operating in its second state of operation the photovoltaic cell is electrically disconnected from the battery; peak current determining means coupled to the battery for determining when the electric current flowing through the battery is at a maximum and for generating an electric signal when the electric current flowing through the battery is at a maximum; and switch control means electrically connected to said switch means and to said peak current determining means for controlling when said switch means is operating in said first state of operation and when said switch means is operating in said second state of operation, wherein said switch control means is responsive to said electric signal generated by said peak current determining means.
Claim 46
Dependent Claim
374 words
Apparatus for controlling electric power that is generated by a photovoltaic cell and delivered to a battery that has positive and negative terminals, wherein the photovoltaic cell also has positive and negative terminals and the photovoltaic cell generates an electric voltage between its positive and negative terminals and a corresponding electric current flowing out of its positive terminal when radiation is incident on the photovoltaic cell, and wherein the battery has an electric voltage between its positive and negative terminals that is approximately constant during a time period, comprising: converter means electrically connected to the photovoltaic cell and to the battery for electrically connecting and disconnecting the photovoltaic cell to and from the battery, for controlling and varying the electric voltage generated between the positive and negative terminals of the photovoltaic cell, and for controlling an electric current that flows through the battery such that the electric power generated by the photovoltaic cell is at a maximum during the time period when the electric current flowing through the battery is at a maximum during the time period, said converter means including a switch means for controlling when said converter means electrically connects the photovoltaic cell to the battery and when said converter means electrically disconnects the photovoltaic cell from the battery, wherein said switch means has a first state of operation and a second state of operation such that when said switch means is operating in its first state of operation the photovoltaic cell is electrically connected to the battery and when said switch means is operating in its second state of operation the photovoltaic cell is electrically disconnected from the battery; peak current determining means coupled to the battery for determining when the electric current flowing through the battery is at a maximum and for generating an electric signal when the electric current flowing through the battery is at a maximum; and switch control means electrically connected to said switch means and to said peak current determining means for controlling when said switch means is operating in said first state of operation and when said switch means is operating in said second state of operation, wherein said switch control means is responsive to said electric signal generated by said peak current determining means.
Claim 47
Dependent Claim
115 words
The apparatus of claim 40, wherein said switch control means includes first electric voltage waveform generator means for generating a triangle electric voltage waveform during the time period, second electric voltage waveform generator means for generating a ramp-shaped electric voltage waveform during a first portion of the time period and a fixed voltage waveform during a second portion of the time period, and comparator means for comparing said electric voltage waveforms produced by said first and second electric voltage waveform generator means and for creating an electric voltage waveform having a varying duty cycle during said first portion of the time period and a fixed duty cycle during said second portion of the time period.
Claim 48
Dependent Claim
27 words
The apparatus of claim 41, wherein the total of said first and second portions of the time period is less than or equal to the time period.
Claim 49
Dependent Claim
70 words
The apparatus of claim 41, wherein said second electric voltage waveform generator means includes a counter means for producing a plurality of electric voltage signals digitally representing a binary number and a digital-to-analog converter means for converting said digitally represented binary number produced by said counter means on said plurality of electric voltage signals to a single voltage signal having an amplitude linearly related to said digitally represented binary number.
Claim 50
Dependent Claim
77 words
The apparatus of claim 43, wherein said second electric voltage waveform generator means further includes latching means electrically disposed between said counter means and said digital-to-analog converter means for allowing said plurality of electric voltage signals produced by said counter means to be input signals to said digital-to-analog converter means during said first portion of the time period, and for latching the input signals to said digital-to-analog converter means during said second portion of the time period.
Claim 51
Dependent Claim
34 words
The apparatus of claim 44, wherein said switch control means further includes a clock means for providing an electric signal to said latching means when said first portion of the time period has started.
Claim 52
Dependent Claim
30 words
The apparatus of claim 44, wherein said switch control means sends an electric signal to said peak current determining means when said first portion of the time period has started.
Claim 53
Dependent Claim
36 words
The apparatus of claim 41, wherein said peak current determining means includes a resistor in electrical series with the battery such that all of the electric current flowing through the battery also flows through said resistor.
Claim 54
Dependent Claim
39 words
The apparatus of claim 47, wherein said peak current determining means further includes a capacitor that is electrically discharged prior to said first portion of the time period and electrically charged during said first portion of the time period.
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