Systems and methods for control of photovoltaic arrays

Patent metadata

Field	Value
Publication number	US-10965126-B2
Application number	US-201715583456-A
Country	US
Kind code	B2
Filing date	May 1, 2017
Priority date	May 1, 2017
Publication date	Mar 30, 2021
Grant date	Mar 30, 2021

Abstract

An apparatus includes a plurality of photovoltaic modules including at least a first and a second photovoltaic module having outputs connected in series by a bus. A voltage detection circuit detects a bus voltage at an output of the bus, to provide an indicator of detected bus voltage to the first photovoltaic module, and to provide the indicator of detected bus voltage to the second photovoltaic module.

First claim

What is claimed is:

1. An apparatus, comprising:
a plurality of photovoltaic modules including at least a first photovoltaic module having a first power circuit controlled by a first duty cycle supplied to the first power circuit by a first controller to generate a first output and a second photovoltaic module having a second power circuit controlled by a second duty cycle supplied to the second power circuit by a second controller to generate a second output;
a bus connecting the plurality of photovoltaic modules, the bus connecting the first output and the second output in series;
a voltage detection circuit to measure a bus voltage at an output of the bus, to provide an indicator of measured bus voltage to the first controller, the indicator is a multi-bit digital value of one or more bytes per data sample from analog to digital conversion of the measured bus voltage by an analog-to-digital converter, the indicator providing information including the total voltage between output terminals of the bus;
the first controller is configured to receive the indicator from the voltage detection circuit, change the first duty cycle for the first power circuit in response to changes in the total voltage between output terminals of the bus indicated by the indicator, and send the indicator to the second controller with additional data; and
the second controller is configured to receive the indicator and the additional data from the first controller, change the second duty cycle of the second power circuit in response to changes in the total voltage between output terminals of the bus indicated by the indicator and the additional data from the first controller.

2. The apparatus of claim 1 , wherein the additional data includes data regarding changes to the first output.

3. The apparatus of claim 2 wherein the additional data includes one or more of duty cycle data for the first photovoltaic module and module output voltage and/or current for the first photovoltaic module.

4. The apparatus of claim 1 wherein the first controller and the second controller independently respond to the indicator of measured bus voltage, combined responses of the plurality of photovoltaic modules drive the bus voltage at the output of the bus to maintain the bus voltage at the output of the bus within a bus voltage range of 200 volts to 500 volts, the apparatus further comprising an inverter connected to the output of the bus and wherein the bus voltage range is in an acceptable input range of the inverter.

5. The apparatus of claim 1 wherein:
the first controller is configured to detect an unbalanced condition by comparing a voltage of the first output with the total voltage between the output terminals divided by a number of photovoltaic modules connected to the bus; and
the second controller is configured to detect an unbalanced condition by comparing a voltage of the second output with the total voltage between the output terminals divided by the number of photovoltaic modules connected to the bus.

6. The apparatus of claim 1 , further comprising a direct communication channel from the analog-to-digital converter to the first controller and a bi-directional communication channel from the first controller to the second controller configured for communication from the first controller to the second controller and communication from the second controller to the first controller.

7. The apparatus of claim 1 wherein the analog-to-digital converter is located within a housing that houses a controller of the first photovoltaic module.

8. The apparatus of claim 1 wherein the voltage detection circuit further comprises a voltage divider configured to reduce a bus voltage to a smaller voltage for sampling by the analog-to-digital converter.

9. The apparatus of claim 1 wherein the plurality of photovoltaic modules includes two or more additional photovoltaic modules, each individual additional photovoltaic module configured to receive the indicator and additional data from one or more upstream photovoltaic modules, change a respective duty cycle in response to changes in the total voltage between output terminals of the bus indicated by the indicator and additional data from the one or more upstream photovoltaic modules, and send the indicator to a downstream photovoltaic module with additional data from the individual additional photovoltaic module.

10. An apparatus, comprising:
a plurality of power modules, each power module of the plurality of power modules having a plurality of power cells connected to a power circuit and a controller to control an output voltage by controlling duty cycle of the power circuit;
a bus connecting the plurality of power modules, the bus connecting outputs of the plurality of power modules in series;
an inverter receiving a direct current (DC) input from the bus and generating an alternating current (AC) output;
a voltage detection circuit to measure the DC input from the bus and to generate an indicator of measured voltage, the indicator is a multi-bit digital value of one or more bytes per data sample from analog to digital conversion of the measured bus voltage, the indicator providing information including the total voltage between output terminals of the bus; and
a plurality of communication channels including:
a first communication channel extending from the voltage detection circuit to a first power module of the plurality of power modules to provide the indicator of the measured bus voltage to the first power module;
a second communication channel extending from the first power module to a second power module of the plurality of power modules to provide the indicator of the measured bus voltage and additional data from the first power module to the second power module;
additional communication channels extending between additional power modules of the plurality of power modules; and
the plurality of communication channels providing the indicator and additional data for individual feedback control by the controllers of duty cycles of the power circuits of the plurality of power modules in response to the total voltage between output terminals of the bus and additional data from controllers of other power modules of the plurality of modules.

11. The apparatus of claim 10 wherein each controller is configured to control an output voltage of a corresponding module, independently of other controllers of other modules, in response to the total voltage between output terminals of the bus.

12. The apparatus of claim 11 wherein each controller is configured to control the output voltage of the corresponding module using Proportional Integral (PI) control in response to the total voltage between output terminals of the bus.

13. The apparatus of claim 10 wherein a power circuit of a power module of the plurality of power modules includes a DC-to-DC converter that has either a boost-buck circuit or a buck-boost circuit, and wherein an output of the power module is generated by the DC-to-DC converter, the duty cycle of the DC-to-DC converter controlled by a corresponding controller in response to the total voltage between output terminals of the bus.

14. The apparatus of claim 13 wherein the output of the power module is controlled by modifying a duty cycle of the DC-to-DC converter using a Pulse Width Modulation (PWM) signal generated by the corresponding controller.

15. The apparatus of claim 10 wherein the plurality of power modules are photovoltaic power modules, each power module of the plurality of power modules having a plurality of photovoltaic cells.

16. The apparatus of claim 10 w

Assignees

• Futurewei Technologies Inc

Inventors

• Zhu Huibin
• Dai Heping
• Mao Xiaolin

Classifications

• H02J2101/25

  involving maximum power point tracking control for photovoltaic sources · CPC title

• H02J2101/24

  Photovoltaics · CPC title

• H02J3/381 Primary

  Dispersed generators · CPC title

• H02J3/46

  Controlling the sharing of generated power between the generators, sources or networks · CPC title

• H02J3/38

  Arrangements for feeding a single network from two or more generators or sources in parallel; Arrangements for feeding already energised networks from additional generators or sources in parallel · CPC title