Systems and methods for controlling power switching converters for photovoltaic panels

Patent metadata

Field	Value
Publication number	US-9577425-B1
Application number	US-201213478939-A
Country	US
Kind code	B1
Filing date	May 23, 2012
Priority date	May 23, 2011
Publication date	Feb 21, 2017
Grant date	Feb 21, 2017

Abstract

A photovoltaic (PV) system has a plurality of PV panels that convert solar energy into electrical energy. Each PV panel is coupled to a respective switching power converter. A parameter (e.g., voltage or current) of a combined current signal from each of the switching power converters is sensed, and a controller controls the duty cycle of each switching power converter in order to maximize the sensed parameter. In this regard, the controller adjusts the duty cycles of the power switching converters in groups while the duty cycles of other power switching converters are held constant in order to set the duty cycles for maximum power transfer, thereby accounting for variations in the power output by each PV panel.

First claim

Now, therefore, the following is claimed:

1. A photovoltaic (PV) energy system, comprising:
a first PV panel;
a first power switching converter coupled to the first PV panel;
a second PV panel;
a second power switching converter coupled to the second PV panel;
a system load coupled to the first power switching converter and the second power switching converter, the system load configured to receive a signal having current from each of the power switching converters;
a sensor configured to sense the current or a voltage of the signal; and
a controller configured to adjust energy transfer characteristics of each of the power switching converters based on the sensed current or voltage, the controller configured to adjust a duty cycle of the first power switching converter during a first time period while keeping a duty cycle of the second power switching converter constant, the controller further configured to adjust the duty cycle of the second power switching converter during a second time period while keeping the duty cycle of the first power switching converter constant, wherein adjustments to the duty cycle of the first power switching converter and adjustments to the duty cycle of the second power switching converter affect the current or the voltage of the signal received by the system load, wherein the controller is configured to set the duty cycle of the first power switching element based on measurements of the current or the voltage of the signal by the sensor during the first time period while the controller is adjusting the duty cycle of the first power switching converter and keeping the duty cycle of the second power switching converter constant, and wherein the controller is configured to set the duty cycle of the second power switching converter based on measurements of the current or the voltage of the signal by the sensor during the second time period while the controller is adjusting the duty cycle of the second power switching converter and keeping the duty cycle of the first power switching converter constant.

2. The system of claim 1 , wherein the controller is configured to apply a maximum power point tracking algorithm to each converter at different instances of time.

3. The system of claim 1 , wherein the first power switching converter is in series with the second power switching converter.

4. The system of claim 1 , wherein the first power switching converter is in parallel with the second power switching converter.

5. A method for use in a photovoltaic (PV) energy system, comprising:
combining current from a first power switching converter with current from a second power switching converter, thereby providing a combined signal, wherein the first power switching converter is coupled to a first PV panel and the second power switching converter is coupled to a second PV panel;
driving a system load with the combined signal;
sensing a current or a voltage of the combined signal with a sensor;
controlling energy transfer characteristics of the first and second power switching converters based on the sensing, wherein the controlling comprises (1) adjusting a duty cycle of the first power switching converter during a first time period and (2) keeping a duty cycle of the second power switching converter constant during the adjusting the duty cycle of the first power switching converter;
adjusting the duty cycle of the second power switching converter during a second time period;
keeping the duty cycle of the first power switching converter constant during the second time period;
setting the duty cycle of the first power switching converter for a third time period based on measurements of the current or the voltage of the combined signal during the first time period while the duty cycle of the first power switching converter is adjusted and the duty cycle of the second power switching converter is kept constant; and
setting the duty cycle of the second power switching converter for the third time period based on measurements of the current or the voltage of the combined signal during the second time period while the duty cycle of the second power switching converter is adjusted and the duty cycle of the first power switching converter is kept constant.

6. A method for use in a photovoltaic (PV) energy system, comprising:
receiving a first signal from a PV panel via a first power switching converter;
receiving a second signal from a PV panel via a second power switching converter;
combining the first signal and the second signal thereby forming a combined signal having current from each of the power switching converters;
receiving the combined signal at a system load coupled to the first power switching converter and the second power switching converter;
sensing, with a sensor, the current or a voltage of the combined signal;
adjusting energy transfer characteristics of each of the power switching converters based on the current or the voltage sensed by the sensing;
adjusting a duty cycle of the first power switching converter during a first time period while a duty cycle of the second power switching converter is held constant; and
adjusting the duty cycle of the second power switching converter during a second time period while the duty cycle of the first power switching converter is held constant,
wherein the adjusting the energy transfer characteristics comprises:
setting the duty cycle of the first power switching converter for a third time period based on measurements of the current or the voltage of the combined signal during the first time period while the duty cycle of the first power switching converter is adjusted and the duty cycle of the second power switching converter is held constant; and
setting the duty cycle of the second power switching converter for the third time period based on measurements of the current or the voltage of the combined signal during the second time period while the duty cycle of the second power switching converter is adjusted and the duty cycle of the first power switching converter is held constant.

7. The system of claim 6 , wherein the first power switching converter is in series with the second power switching converter.

8. The system of claim 6 , wherein the first power switching converter is in parallel with the second power switching converter.

Assignees

• Abu Qahouq Jaber A
• Univ Alabama

Inventors

• Abu Qahouq Jaber A

Classifications

• H02J1/102 Primary

  being switching converters (H02J1/108, H02J1/12 take precedence) · CPC title

• H10F77/955

  for photovoltaic devices · CPC title

• Y02E10/50

  Photovoltaic [PV] energy · CPC title