Photovoltaic power conditioning units
First Claim
1. A photovoltaic (PV) power conditioning unit for delivering power from a PV panel to an ac power supply output, the PV panel comprising a string of series-connected solar cells with at least one electrical tap connection on said string to define a set of series-connected sub-strings of said solar cells, the PV power conditioning unit comprising:
- a plurality of input power converters, one for each said sub-string, each input power converter having a pair of dc input connections for connection to either end of a sub-string in the set of sub-strings, each of said input power converters having a power output, wherein each electrical tap connection on said string connects to a dc input connection of each of two power converters in the plurality of input power converters;
a sub-string sensing system comprising a voltage-programmed current source having a set of current programming inputs, each current programming input to receive a voltage signal from a sub-string in the set of sub-strings and having a corresponding programmed current output to output a programmed current dependent on a level of said voltage signal;
at least one input power converter controller coupled to said sub-string sensing system to control a level of power conversion of one or more input power converters responsive to a voltage from a particular sub-string received by the sub-string sensing system, wherein said programmed current output corresponding to the particular sub-string is coupled to a current-to-voltage converter to convert said programmed current to a voltage dependent on said programmed current for input to said input power converter controller;
a shared dc link to provide a common dc bus for said plurality of input power converters, wherein said power output of each said input power converter is coupled to said shared dc link to provide power from a sub-string in the set of sub-strings to said dc bus;
an energy storage capacitor, coupled to said shared dc link, to store power from said plurality of input power converters for delivering to said ac power supply output; and
a common output power conversion stage coupled to said shared dc link to convert dc power from said shared dc link to ac power to provide an ac output from said PV power conditioning unit.
4 Assignments
0 Petitions
Accused Products
Abstract
We describe a photovoltaic (PV) panel power conditioning circuits, in particular for a PV panel with multiple sub-strings of connected solar cells. The power conditioning unit comprises a set of input power converters, one connected to each sub-string, a shared dc link to provide a common dc bus for the set of input power converters, and a common output power conversion stage coupled to the shared dc link to convert power from the shared dc link to ac power for a mains power supply output from the power conditioning unit. Local conversion of the sub-strings facilitates control of the power available from the panel and optimum energy harvesting, as well as local maximum power point tracking (MPPT) adjustment.
126 Citations
17 Claims
-
1. A photovoltaic (PV) power conditioning unit for delivering power from a PV panel to an ac power supply output, the PV panel comprising a string of series-connected solar cells with at least one electrical tap connection on said string to define a set of series-connected sub-strings of said solar cells, the PV power conditioning unit comprising:
-
a plurality of input power converters, one for each said sub-string, each input power converter having a pair of dc input connections for connection to either end of a sub-string in the set of sub-strings, each of said input power converters having a power output, wherein each electrical tap connection on said string connects to a dc input connection of each of two power converters in the plurality of input power converters; a sub-string sensing system comprising a voltage-programmed current source having a set of current programming inputs, each current programming input to receive a voltage signal from a sub-string in the set of sub-strings and having a corresponding programmed current output to output a programmed current dependent on a level of said voltage signal; at least one input power converter controller coupled to said sub-string sensing system to control a level of power conversion of one or more input power converters responsive to a voltage from a particular sub-string received by the sub-string sensing system, wherein said programmed current output corresponding to the particular sub-string is coupled to a current-to-voltage converter to convert said programmed current to a voltage dependent on said programmed current for input to said input power converter controller; a shared dc link to provide a common dc bus for said plurality of input power converters, wherein said power output of each said input power converter is coupled to said shared dc link to provide power from a sub-string in the set of sub-strings to said dc bus; an energy storage capacitor, coupled to said shared dc link, to store power from said plurality of input power converters for delivering to said ac power supply output; and a common output power conversion stage coupled to said shared dc link to convert dc power from said shared dc link to ac power to provide an ac output from said PV power conditioning unit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
-
-
14. A photovoltaic (PV) power conditioning unit for delivering power from a PV panel to an ac power supply output, the PV panel comprising a string of series-connected solar cells with at least one electrical tap connection on said string to define a set of series-connected sub-strings of said solar cells, the power conditioning unit comprising:
-
a set of input power converters, one for each said sub-string, each input power converter having a pair of dc input connections for connection to either end of each of two sub-strings, each of said input power converters having a power output; a shared dc link to provide a common dc bus for said set of input power converters, wherein said power output of each said input power converters is coupled to said shared dc link to provide power from a sub-string in the set of sub-strings to said dc bus, wherein each input power converter comprises a dc-to-ac converter, wherein said dc-to-ac converters of said input power converters for said sub-strings are synchronized such that each operates at a successive relative phase offset of (180°
/n) or (360°
/n) to reduce a voltage ripple on said dc link, wherein n is a number of the input power converters;an energy storage capacitor, coupled to said shared dc link, to store power from said PV panel for delivering to said ac power supply output; and a common output power conversion stage coupled to said shared dc link to convert dc power from said shared dc link to ac power to provide an ac output from said PV power conditioning unit.
-
-
15. A photovoltaic (PV) power conditioning unit for delivering power from a PV panel to an ac power supply output, the PV panel comprising a string of series-connected solar cells with at least one electrical tap connection on said string to define a set of series-connected sub-strings of said solar cells, the power conditioning unit comprising:
a sensing circuit to sense a voltage or current from one or more of said solar cells, said sensing circuit comprising; a sense input to receive a voltage signal from said one or more solar cells dependent on said sensed voltage or current; and a voltage-programmed current source having a current programming input coupled to said sense input, and having a programmed current output to output a programmed current dependent on a level of said voltage signal, wherein said programmed current output is coupled to a current-to-voltage converter to convert said programmed current to a voltage output from the sensing circuit dependent on said programmed current. - View Dependent Claims (16, 17)
Specification