Constraint Weighted Regulation of DC/DC Converters

• US 20110187198A1
• Filed: 02/03/2011
• Published: 08/04/2011
• Est. Priority Date: 02/03/2010
• Status: Active Grant

• Current Assignee: Also Energy Incorporated
• Original Assignee: Blue Acquisition Group Incorporated (The J. M. Smucker Company)
• Inventors: Sandbote, Sam B., Williams, Bertrand J.
• Granted Patent: US 9,142,960 B2
• Time in Patent Office: Days
• US Class Current: 307/71
• CPC Class Codes: G05F 1/67 to the maximum power available from a generator, e.g. from solar cell
• CPC Class Codes: H02J 1/12 Parallel operation of dc generators with converters, e.g. with mercury-arc rectifier
• CPC Class Codes: H02J 2300/26 involving maximum power point tracking control for photovoltaic sources maximum power point systems in particular G05F1/67
• CPC Class Codes: H02J 3/381 Dispersed generators
• CPC Class Codes: H02M 3/02 without intermediate conversion into ac
• CPC Class Codes: Y02E 10/56 Power conversion systems, e.g. maximum power point trackers

Abstract

A converter unit to improve overall recovered power in a photovoltaic array configuration. Each photovoltaic panel in the photovoltaic array may be coupled to a respective converter unit, which may include a controller to sense an output voltage and output current produced by the solar panel, and manage the output voltage of a corresponding power converter to optimize and regulate the resultant bus voltage to a point which reduces overall system losses, maintains a low loss condition, and removes series-string non-idealities when the panels are series connected. The controller may also adapt to output condition constraints. Instead of single-port regulation, a combination of input voltage and output voltage management and regulation may be performed within the converter. The source voltage and current characteristic may be shaped to correspond to an optimized power curve at the desired bus voltage to allow MPPT tracking according to the DC voltage bus. The optimized power curve may be tracked to hold the DC-bus voltage at the desired operating point.

Claims

1. A control system for controlling a power converter configured to couple to a solar panel to provide an output voltage and an output current to a voltage bus, the control system comprising:

one or more input ports, each given input port of the one or more input ports configured to receive one of a plurality of parameters comprising;

a first parameter indicative of an input current of the power converter originating from the solar panel;

a second parameter indicative of an input voltage of the power converter originating from the solar panel;

a third parameter indicative of an output voltage of the power converter; and

a fourth parameter indicative of an output current of the power converter; and

a controller configured to regulate the input voltage of the power converter according to an MPPT (maximum power point tracking) algorithm, and further configured to regulate output power of the power converter to effect a shaped power transfer characteristic on the voltage bus, wherein the shaped power transfer characteristic sufficiently resembles a power transfer characteristic of the solar panel.

2. The control system of claim 1, wherein the controller is configured to regulate the output power of the power converter according to a specified mathematical function.

3. The control system of claim 1, wherein the controller is configured to regulate the input voltage of the power converter by setting a dominant value for a first control signal used for adjusting the output voltage of the power converter.

4. The control system of claim 3, wherein an output of the power converter operates as a virtual constant power port, wherein in regulating the output power of the power the controller is configured to adjust the dominant value of the first control signal to provide emphasis at the virtual constant power port around a preferred output voltage range of the power converter.

5. The control system of claim 1, wherein the controller is configured to regulate the output power of the power converter such that the output voltage of the power converter does not exceed a specified maximum value.

6. The control system of claim 1, wherein the controller is configured to regulate the input voltage of the power converter and suspend regulating the output power of the power converter when the output voltage of the power converter is within a specified first voltage value range.

7. The control system of claim 1, wherein the controller is configured to regulate the output power of the power converter according to a weighted constraint corresponding to the output voltage of the power converter.

8. A control system for controlling a power converter configured to couple to a solar panel to provide an output voltage and output current to a voltage bus, the control system comprising:

a sensing circuit configured to sense input current and input voltage of the power converter derived from the solar panel, and further configured to sense output voltage and output current of the power converter;

a controller configured to regulate the input voltage of the power converter according to the sensed input current and sensed input voltage of the power converter and according to the sensed output voltage and sensed output current of the power converter to optimize power derived from the solar panel, and further configured to regulate output power of the power converter to effect a desired power transfer characteristic on the voltage bus, wherein the desired power transfer characteristic sufficiently resembles a power transfer characteristic of the solar panel.

9. The control system of claim 8, wherein the controller is configured to regulate the output power of the power converter according to a specified mathematical function corresponding to the desired power transfer characteristic.

10. The control system of claim 8, wherein the power converter is a switching power converter;

and

wherein the controller is configured to regulate the input voltage of the power converter by setting a dominant pulse timing for a pulse-width modulated (PWM) signal provided as a switching signal to the power converter.

11. The control system of claim 10, wherein an output of the power converter operates as a virtual constant power port, wherein in controlling the output power of the power converter, the controller is configured to adjust the dominant pulse timing of the PWM signal to provide emphasis at the virtual constant power port around a preferred output voltage range of the power converter.

12. The control system of claim 8, wherein the controller is configured to regulate the output power of the power converter such that the output voltage of the power converter does not exceed a specified maximum value.

13. The control system of claim 8, wherein the controller is configured to regulate the input voltage of the power converter and suspend regulating the output power of the power converter when the output voltage of the power converter is within a specified first voltage value range.

14. A method for controlling a power converter coupled to a solar panel to provide an output voltage and an output current to a voltage bus, the method comprising:

monitoring input voltage and input current of the power converter;

monitoring output voltage and output current of the power converter;

regulating the input voltage of the power converter according to an MPPT (maximum power point tracking) algorithm using parameters corresponding to;

the monitored input voltage and monitored input current of the power converter; and

the monitored output voltage and output current of the power converter; and

regulating output power of the power converter to effect a shaped power transfer characteristic on the voltage bus, wherein the shaped power transfer characteristic sufficiently resembles a power transfer characteristic of the solar panel.

15. The method of claim 14, wherein said monitoring comprises obtaining digitized values corresponding to the input voltage and input current of the power converter and the output voltage and output current of the power converter, and using the digitized values as the parameters.

16. The method of claim 14, wherein said regulating the output power of the power converter comprises regulating the output power of the power converter according to a specified function of the output voltage of the power converter.

17. The method of claim 14, wherein said regulating the input voltage of the power converter comprises setting a dominant value for a control signal, the method further comprising:

adjusting the output voltage of the power converter using the first control signal.

18. The method of claim 17, wherein an output of the power converter operates as a virtual constant power port, wherein said regulating the output power of the power the controller comprises:

adjusting the dominant value of the control signal to provide emphasis at the virtual constant power port around a preferred output voltage range of the power converter.

19. A converter unit comprising:

a power converter having an input configured to couple to a solar panel to receive an input voltage and input current from the solar panel, and an output configured to couple to a voltage bus to provide a converter output voltage and a converter output current to the voltage bus; and

a control unit comprising;

one or more input ports, each given input port of the one or more input ports configured to receive one of a plurality of parameters comprising;

a first parameter indicative of an input current of the power converter;

a second parameter indicative of an input voltage of the power converter;

a third parameter indicative of the converter output voltage; and

a fourth parameter indicative of the converter output current; and

a controller configured to regulate the input voltage of the power converter according to a first function, and further configured to regulate output power of the power converter according to a second function.

20. The converter unit of claim 19, wherein in regulating the output power of the power converter according to the second function, the controller is configured to effect a shaped power transfer characteristic on the voltage bus, wherein the shaped power transfer characteristic sufficiently resembles a power transfer characteristic of the solar panel.

21. The converter unit of claim 19, wherein the first function is a maximum power point tracking (MPPT) algorithm.

22. The converter unit of claim 19, wherein the power converter is a switching DC/DC converter.

23. A system for harnessing photonic energy to provide power to one or more loads, the system comprising:

a plurality of solar power panels, wherein each given solar panel of the plurality of solar panels provides a respective output current and a respective output voltage;

a DC voltage bus providing a DC bus voltage;

a plurality of converter units coupled to the DC voltage bus, each converter unit of the plurality of converter units configured to provide a respective converter output voltage to the DC voltage bus, wherein each given solar panel is coupled to a corresponding converter unit of the plurality of converter units to provide its respective output current and its respective output voltage as inputs to its corresponding converter unit, wherein each corresponding converter unit comprises a switching power module that produces a respective converter output voltage and respective converter output current, and wherein each corresponding converter unit is configured to;

regulate an input voltage of its switching power module according to an MPPT (maximum power point tracking) algorithm receiving parameters as inputs, wherein the parameters correspond to one or more of;

the input voltage and input current of the switching power module; and

the respective converter output voltage, and the respective converter output current; and

regulate output power of the switching power module according to a function of the respective converter output voltage; and

a DC/AC inverter that inverts the DC bus voltage to an AC power signal for distribution to one or more AC loads.

24. The system of claim 23, wherein the plurality of converter units are series connected to the DC voltage bus via their respective outputs.

25. The system of claim 23, wherein the plurality of converter units are parallel connected to the DC voltage bus via their respective outputs.