Enhanced System and Method for String-Balancing

• US 20130026842A1
• Filed: 03/12/2012
• Published: 01/31/2013
• Est. Priority Date: 07/28/2011
• Status: Active Grant

• Current Assignee: Tigo Energy, Inc
• Original Assignee: Tigo Energy, Inc
• Inventors: Arditi, Shmuel, Hadar, Ron
• Granted Patent: US 9,368,965 B2
• Time in Patent Office: Days
• US Class Current: 307/82
• CPC Class Codes: H02J 1/10 Parallel operation of dc sources
• CPC Class Codes: H02J 13/00 Circuit arrangements for providing remote indication of network conditions, e.g. an instantaneous record of the open or closed condition of each circuitbreaker in the network; Circuit arrangements for providing remote control of switching means in a power distribution network, e.g. switching in and out of current consumers by using a pulse code signal carried by the network
• CPC Class Codes: H02J 13/00007 using the power network as support for the transmission
• CPC Class Codes: H02J 2300/24 of photovoltaic origin
• 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 3/38 Arrangements for parallely feeding a single network by two or more generators, converters or transformers
• CPC Class Codes: H02J 3/381 Dispersed generators
• CPC Class Codes: Y02E 10/56 Power conversion systems, e.g. maximum power point trackers
• CPC Class Codes: Y02E 40/70 Smart grids as climate change mitigation technology in the energy generation sector
• CPC Class Codes: Y02E 60/00 Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
• CPC Class Codes: Y04S 10/123 the energy generation units being or involving renewable energy sources
• CPC Class Codes: Y04S 40/121 using the power network as support for the transmission

Abstract

Apparatuses and methods for configuring and managing solar panels to form strings of photovoltaic energy generators with improved performance and reduced cost. The photovoltaic energy generators are connected via one or more combined local management units (CLMUs), each having a plurality of direct current converters connected to and configured to receive direct current power from a respective solar panel. A controller unit shared by the CLMU'"'"'s direct current converters is utilized to separately control the operation of each converter such that the power extracted from the solar panels is maximized. A communications unit coupled with the controller unit is utilized to facilitate communications between the controller unit and a system unit remote from the CLMU to report measurements and receive control signals.

Claims

1. A method for string balancing a plurality of photovoltaic panels connected in a plurality of strings in turn connected in parallel to a bus comprising:

sensing a string voltage on each of the plurality of strings;

setting the string having a highest voltage as Vsmax; and

up-converting voltage on the remaining strings to match Vsmax.

2. The method of claim 1 wherein up-converting comprises providing a dc-to-dc converter in series with each string to match voltage to Vsmax.

3. The method of claim 2 wherein the up-converting includes connecting a Vsupply to each dc-to-dc converter to provide additional voltage.

4. The method of claim 3 wherein the up-converting includes providing a portion of string output as the Vsupply to the dc-to-dc converter.

5. The method of claim 3 wherein the Vsupply is a separate voltage source.

6. A photovoltaic distribution system comprising:

a plurality of photovoltaic panels connected in a plurality of strings in turn connected in parallel to a bus; and

each string having a dc-to-dc converter connected in series to the bus, wherein each converter is configured to match string current and voltage to one of the strings having a highest voltage, Vsmax.

7. The system of claim 6 wherein one or more of the dc-to-dc converters has a separate voltage supply connected to supplement string voltage to achieve Vsmax.

8. The system of claim 6 wherein one or more of the dc-to-dc converters uses a portion of its string voltage as a voltage supply to achieve Vsmax.

9. The system of claim 8 wherein each dc-to-dc converter uses string voltage as the voltage supply to achieve Vsmax.

10. The system of claim 6 further comprising each string having a control unit connected thereto communicating with a controller to determine Vsmax.