Method for controlling single-phase DC/AC converters and converter arrangement

Patent metadata

Field	Value
Publication number	US-9257848-B2
Application number	US-73287110-A
Country	US
Kind code	B2
Filing date	Mar 26, 2010
Priority date	Mar 26, 2009
Publication date	Feb 9, 2016
Grant date	Feb 9, 2016

Abstract

A method is disclosed for controlling single-phase DC/AC converters, along with a converter arrangement having at least two single-phase DC/AC converters. A controller is provided which can control the at least two single-phase DC/AC converters, and an isolation transformer, wherein outputs of the at least two single-phase DC/AC converters are cascade-connected with each other and an input of the isolation transformer. The controller is configured to control the at least two single-phase DC/AC converters to deliver power from their inputs to their outputs by turns.

First claim

What is claimed is:

1. A converter arrangement comprising:
at least two single-phase DC/AC converters;
control means for controlling the at least two single-phase DC/AC converters, the control means being configured to control the at least two single-phase DC/AC converters to deliver power from their inputs to their outputs by turns; and
an isolation transformer,
wherein outputs of said at least two single-phase DC/AC converters are cascade-connected with each other and an input of the isolation transformer.

2. The arrangement of claim 1 , wherein the control means are configured to control each of the at least two single-phase DC/AC converters to deliver power from its input to its output in delivery periods such that each of the at least two single-phase DC/AC converters has one delivery period during a predetermined switching period
wherein, when a number of the at least two single-phase DC/AC converters is N, a length of one such delivery period is 100%/ 2 N of the predetermined switching period and starting times of two successive delivery periods by two different single-phase DC/AC converters are spaced by 100%/N of the predetermined switching period.

3. The arrangement of claim 2 , wherein each of the at least two single-phase DC/AC converters comprises:
a half bridge having two controllable switches, and the control means are configured to control the at least two single-phase DC/AC converters by controlling the switches.

4. The arrangement of claim 3 , wherein the two controllable switches of each DC/AC converter comprise:
a first switch connected to a positive DC pole of the DC/AC converter and a second switch connected to a negative DC pole of the DC/AC converter,
wherein the control means are configured to control the first switch of each of the at least two single-phase DC/AC converter to be conductive for the delivery period of the DC/AC converter it belongs to, and to control the second switch of each of the at least two single-phase DC/AC converters to, be conductive when the first switch of the same DC/AC converter is not conductive.

5. The arrangement of claim 4 , wherein two output poles of each of the at least two single-phase DC/AC converters are formed by a negative output of the DC/AC converter and a connection point of the two controllable switches.

6. The arrangement of claim 5 , wherein the at least two single-phase DC/AC converters are connected to the isolation transformer via a resonant capacitance.

7. The arrangement of claim 4 , wherein two output poles of each of the at least two single-phase DC/AC converters are formed by a connection point of two mutually series-connected capacitances, which are connected in parallel with the two controllable switches, and the connection point of the two controllable switches.

8. The arrangement of claim 7 , wherein the two mutually series-connected capacitances are configured to operate as resonant capacitances.

9. The arrangement of claim 1 , wherein the at least two single-phase DC/AC converters and the isolation transformer operate in a resonant mode.

10. The arrangement of claim 1 , comprising: an AC/AC converter supplied by the isolation transformer.

11. The arrangement of claim 1 , comprising: means for supplying each of the single-phase DC/AC converters by at least one photovoltaic cell.

12. The arrangement of claim 11 , wherein the means for supplying the single-phase DC/AC converter by at least one photovoltaic cell comprises: a DC/DC converter.

13. A method for controlling single-phase DC/AC converters in an arrangement having at least two single-phase DC/AC converters and an isolation transformer, the method comprising:
cascade-connecting outputs of said at least two single-phase DC/AC converters with each other and an input of the isolation transformer; and
controlling, in turns, each of the at least two single-phase DC/AC converters to deliver power from its input to its output in delivery periods such that each of the at least two single-phase DC/AC converters has one delivery period during a predetermined switching period
wherein, when a number of the at least two single-phase DC/AC converters is N, a length of one such delivery period is 100%/ 2 N of the predetermined switching period and starting times of two successive delivery periods by two different single-phase DC/AC converters are spaced by 100%/N of the predetermined switching period.

14. The method of claim 13 , wherein the at least two single-phase DC/AC converters each comprise:
a half bridge having two controllable switches, wherein the controlling of the at least two single-phase DC/AC converters is performed by controlling the switches.

15. The method of claim 14 , wherein the two controllable switches comprise a first switch connected to a positive DC pole of the converter and a second switch connected to a negative DC pole of the converter, and wherein the controlling of the switches comprises:
controlling the first switch of each of the at least two single-phase DC/AC converters to be conductive for the delivery period of the DC/AC converter it belongs to; and
controlling the second switch of each of the at least two single-phase DC/AC converters to be conductive when the first switch of the same DC/AC converter is not conductive.

16. A computer program product configured as a non-transitory computer readable medium containing computer program code, wherein execution of the program code in a computer causes the computer to perform a method comprising:
controlling, in turns, each of the at least two single-phase DC/AC converters, the outputs of which are cascade-connected with each other and an input of an isolation transformer, to deliver power from its input to its output in delivery periods such that each of the at least two single-phase DC/AC converters has one delivery period during a predetermined switching period wherein, when a number of the at least two single-phase DC/AC converters is N, a length of one such delivery period is 100%/ 2 N of the predetermined switching period and starting times of two successive delivery periods by two different single-phase DC/AC converters are spaced by 100%/N of the predetermined switching period.

17. A converter system comprising:
at least two single-phase DC/AC converters; a controller configured to control the at least two single-phase DC/AC converters to deliver power from their inputs to their outputs by turns; and
an isolation transformer,
wherein outputs of said at least two single-phase DC/AC converters are cascade-connected with each other and an input of the isolation transformer.

Assignees

• Coccia Antonio
• Canales Francisco
• Serpa Leonardo-Augusto
• Paakkinen Mikko
• Abb Research Ltd

Inventors

• Coccia Antonio
• Canales Francisco
• Serpa Leonardo-Augusto
• Paakkinen Mikko

Classifications

• H02M7/49

  Combination of the output voltage waveforms of a plurality of converters · CPC title

• H02J2101/24

  Photovoltaics · CPC title

• H02J4/25

  for transfer of electric power between AC and DC networks, e.g. for supplying the DC section within a load from an AC mains system · CPC title

• H02J3/383 Primary

  Electricity · mapped topic

• Y10T307/707

  Cross-Sectional Technologies · mapped topic