Multi-string inverter having input-side EMC filter

Patent metadata

Field	Value
Publication number	US-9614427-B2
Application number	US-201514683301-A
Country	US
Kind code	B2
Filing date	Apr 10, 2015
Priority date	Oct 10, 2012
Publication date	Apr 4, 2017
Grant date	Apr 4, 2017

Abstract

An inverter includes a DC/AC converter, a DC intermediate circuit on the direct current input side of the DC/AC converter, multiple DC/DC converters connected in parallel to one another on the output side to the DC intermediate circuit, multiple inputs each coupled to one of the DC/DC converters, and an EMC filter connected between the inputs and the DC/DC converters. The EMC filter includes chokes in all current-carrying lines between the inputs and the DC/DC converters and filter capacitors between the inputs and the DC/DC converters leading from all the current-carrying lines to ground. The chokes in all current-carrying lines from the at least two inputs are formed by means of choke windings on a common core of a current-compensated choke.

First claim

The invention claimed is:

1. An inverter, comprising:
a DC/AC converter,
a DC intermediate circuit coupled to a direct current input side of the DC/AC converter,
multiple DC/DC converters connected in parallel to one another on an output side thereof, wherein the output side of the multiple DC/DC converters is coupled to the DC intermediate circuit,
multiple inputs that are each coupled to an input of one of the DC/DC converters, respectively,
an EMC filter connected between the multiple inputs and the inputs of the DC/DC converters,
wherein the EMC filter comprises:
chokes in all current-carrying lines between the multiple inputs and the inputs of the DC/DC converters, and
filter capacitors that lead from all the current-carrying lines to ground between the multiple inputs and the inputs of the DC/DC converters,
wherein one of the current-carrying lines comprises a common current-carrying line that leads from an input to the multiple DC/DC converters, and
wherein the chokes in all the current-carrying lines comprise choke windings on a common core of a current-compensated choke; and

a controller configured to control switches of the DC/DC converters in a synchronous manner when the multiple inputs of the inverter are connected in parallel by means of hard-wiring their current-carrying lines.

2. The inverter as claimed in claim 1 , wherein the chokes each comprise an inductance of between 0.2 mH to 4.0 mH.

3. The inverter as claimed in claim 1 , wherein the choke winding for the choke in the common current-carrying line comprises a line cross-section that is n-times greater than the choke winding for each choke in one of the current-carrying lines that is not the common current-carrying line, wherein n is the number of the inputs.

4. The inverter as claimed in claim 3 , wherein the n-times greater line cross-section of the choke winding in the common current-carrying line is a line cross-section of an individual thick wire conductor.

5. The inverter as claimed in claim 3 , wherein the n-times greater line cross-section of the choke winding in the common current-carrying line is a total line cross-section of multiple parallel guided wire conductors.

6. The inverter as claimed in claim 1 , wherein the choke windings are wound on the common core in a symmetrical manner.

7. The inverter as claimed in claim 1 , wherein the common core is a core that is not provided with slots.

8. The inverter as claimed in claim 1 , wherein the common core is arranged in an upright manner within a housing of the inverter, wherein the choke winding for the choke in the common current-carrying line is arranged at a location within the inverter that is more easily accessible to a cooling air current for the current-compensated choke in comparison to the choke windings for each choke in one of the current-carrying lines that are not common current-carrying lines.

9. The inverter as claimed in claim 1 , wherein the filter capacitors between the chokes and the DC/DC converters are coupled to ground.

10. The inverter as claimed in claim 9 , wherein the filter capacitors are each coupled to ground through series-connected resistors.

11. The inverter as claimed in claim 10 , wherein the filter capacitors comprise a capacitance of at least 47 nF and the resistors comprise an ohmic resistance of between 0.5 to 10 ohm.

12. The inverter as claimed in claim 9 , further comprising other filter capacitors between the inputs and the chokes, wherein the other filter capacitors are coupled to ground and are not damped with resistors, and comprise a smaller capacitance than the filter capacitors that are coupled at one node between the chokes and the DC/DC converters and coupled to ground.

13. The inverter as claimed in claim 12 , wherein the other further filter capacitors comprise a capacitance of between 0.2 nF to 33 nF.

14. An operation method for an inverter comprising:
providing an inverter comprising:
a DC/AC converter,
a DC intermediate circuit coupled to a direct current input side of the DC/AC converter,
multiple DC/DC converters connected in parallel to one another on an output side thereof, wherein the output side of the multiple DC/DC converters is coupled to the DC intermediate circuit,
multiple inputs that are each coupled to an input of one of the DC/DC converters, respectively, wherein the multiple inputs are connected in parallel by means of hard-wiring their current-carrying lines,
an EMC filter connected between the multiple inputs and the inputs of the DC/DC converters,
wherein the EMC filter comprises:
chokes in all current-carrying lines between the multiple inputs and the inputs of the DC/DC converters, and
filter capacitors that lead from all the current-carrying lines to ground between the multiple inputs and the inputs of the DC/DC converters,
wherein one of the current-carrying lines comprises a common current-carrying line that leads from an input to the multiple DC/DC converters, and
wherein the chokes in all the current-carrying lines comprise choke windings on a common core of a current-compensated choke; and

a controller configured to control switches of the DC/DC converters; and

controlling the switches of the DC/DC converters in a synchronous manner via the controller.

Assignees

• Sma Solar Technology Ag

Inventors

• Berger Niels
• Napierala Tomasz
• Buchhold Stefan
• Pinne Julia
• Rueckmann Frank
• Wolf Henrik

Classifications

• H02M3/1584

  with a plurality of power processing stages connected in parallel · CPC title

• H02M1/44

  Circuits or arrangements for compensating for electromagnetic interference in converters or inverters · CPC title

• H02M7/48

  using discharge tubes with control electrode or semiconductor devices with control electrode · CPC title

• H02M7/44

  by static converters · CPC title

• H02J2101/25

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