Device for feeding electric energy into a power grid and DC converter for such a device

A DC converter for a device for feeding electric energy into a power grid and for arrangement between a direct voltage generator and an inverter with a bipolar voltage intermediate circuit, wherein the DC converter comprises at least two diodes, one switch and one storage reactor containing one first winding and one second winding, these two windings being magnetically coupled together in such a manner that, in a first switching condition, the first winding is loaded by the direct voltage generator and the second winding via the first winding by virtue of the magnetic coupling and that, in a second switching condition, the two windings are unloaded via a respective one of the two capacitors, which is associated, and via an associated diode, wherein a first terminal of the first winding is connected to a first connection point with a first switch and that a second terminal of the first winding is connected to a second switch at a second connection point in such a manner that the first winding forms, together with the two switches, a first electric circuit connected to associated outputs of the direct voltage generator and moreover lies in a second electric circuit that leads from the ground terminal through a first diode, the first connection point, the first winding, the second connection point, a second diode and the capacitor associated thereto back to the ground terminal and that the second winding is arranged in a third electric circuit that leads from the ground terminal, via the capacitor associated to said winding, via a third diode and the second winding back to the ground terminal.

A device for feeding electric energy into a power grid, comprising:

• a DC converter configured to receive energy from a direct voltage generator;
• and
• an inverter coupled to the DC converter and configured to provide electric energy to the power grid, the inverter comprising:
• a first capacitor and a second capacitor connected together in series at a ground node that forms a negative output terminal of the inverter and couples to a negative output of the DC converter;
• and
• a half bridge circuit comprising first and second series-connected switches coupled in parallel with the first and second capacitors, wherein a connecting node between the first and second series-connected switches form a positive output terminal of the inverter,
• wherein the DC converter further comprises:
• a storage reactor comprising first and second windings that are magnetically coupled together;
• first and second switches coupled to the storage reactor, wherein in a first switching condition the first and second switches are configured to load the first winding and thus the second winding via magnetic coupling via a first electric circuit, and in a second switching condition the first and second windings are unloaded to one of the first and second capacitors;
• first and second diodes coupled to the storage reactor and configured to unload the first and second windings to one of the first and second capacitors via a second electric circuit, when the first and second switches are in the second switching condition;
• a third diode configured to form a third electric circuit with the other of the first and second capacitors and the second winding.