Granted Patent B2

US 12,244,218 · App. 18/022,551 · Granted Mar 4, 2025

Inventors: ChunMing Yuan (Beijing, CN); Peter Steimer (Ehrendingen, CH); Adrian Timbus (Mellingen, CH); Philippe Maibach (Muhen, CH); Juergen Steinke (Albbruck, DE); Stephane Isler (Faucigny, FR); Ralph Burkart (Zürich, CH)

Assignee: HITACHI ENERGY LTD

H02M1/0067H02M3/33576

Abstract

Claims (49)

1. A power grid, comprising

a converting stage comprising a plurality of DC/DC converters;

at least one of the DC/DC converters being a single-stage isolated DC/DC converter comprising a voltage control configured to control a voltage of the respective DC/DC converter;

the DC/DC converters being connected in series;

wherein at least one of the plurality of converters of the converting stage is configured to provide a respective predetermined output voltage to a load;

each of the plurality of DC/DC converters comprising a plurality of DC/AC converters, a plurality of AC/DC converters, wherein the at least one DC/AC converter and the at least one AC/DC converter are configured to be connected to a transformer unit, the transformer unit comprising a plurality of transformers coupling the plurality of DC/AC converters to the plurality of AC/DC converters; and

at least two of the plurality of transformers being connected by an impedance circuit;

the impedance circuit comprising a winding and an impedance for at least two of the plurality of AC/DC converters; and

the windings and the impedances being interconnected.

2. The power grid according to claim 1 , wherein each of the plurality of DC/DC converters comprises at least one DC/AC converter, a plurality of AC/DC converters, wherein the at least one DC/AC converter and the at least one AC/DC converter are configured to be connected to a transformer unit, the transformer unit comprising at least one transformer coupling the at least one DC/AC converter to the plurality of AC/DC converters;

wherein the transformer unit comprises one winding per DC/AC converter and one winding per AC/DC converter, and the windings of the transformer unit share a common core.

3. The power grid according to claim 1 , further comprising another converting stage upstream of the plurality of DC/DC converters,

wherein the other converting stage comprises a DC/DC converter having a controlled voltage output; or

wherein the other converting stage comprises an AC/DC converter having a controlled voltage output.

4. The power grid according to claim 1 , wherein each of the plurality of DC/DC converters comprises a plurality of DC/AC converters, a plurality of AC/DC converters, wherein the at least one DC/AC converter and the at least one AC/DC converter are configured to be connected to a transformer unit, the transformer unit comprising a transformer coupling the plurality of DC/AC converters to the plurality of AC/DC converters;

wherein the power grid further comprises a plurality of second DC/DC converters upstream of and connected to each of the plurality of DC/AC converters;

wherein the second DC/DC converters are connected in series;

wherein particularly an impedance is connected between two of the plurality of second DC/DC converters; and

wherein particularly a capacitor is connected in parallel to the plurality of second DC/DC converters.

5. The power grid according to claim 1 , further comprising a power distribution unit configured to distribute the power to at least one consumer load,

wherein the power distribution unit particularly comprises at least one switch per converter of the second converting stage configured to connect or disconnect outputs of at least two converters of the second converting stage.

6. The power grid according to claim 5 , wherein the power distribution unit comprises a plurality of switches per converter configured to connect or disconnect outputs of the second converting stage, wherein the number of switches corresponds to the number of loads.

7. The power grid according to claim 5 , wherein the power distribution unit further comprises a control unit configured to control the at least one switch to distribute power according to loads and/or sources connected to the power grid, and/or

wherein the control unit is configured to manage assignment of the output voltages of the plurality of converters of the second converting stage according to loads and/or sources connected to the power grid.

8. The power grid according to claim 1 , wherein the power grid further comprises a DC current limiting and/or breaking unit.

9. The power grid according to claim 1 , wherein the power grid is connected to a Medium Voltage Direct Current, MVDC, and wherein particularly the MVDC is variable.

10. The power grid according to claim 1 , wherein the power grid is connectable to at least one of variable speed heatpump systems, hyperscale datacenters, distributed battery energy storage, physically distributed or collocated DC chargers, and renewable energy sources.

11. A method for controlling a power grid according to claim 1 , the method comprising:

converting, by a converting stage comprising a plurality of DC/DC converters, an input voltage into an output voltage,

connecting the plurality of DC/DC converters in series, wherein each of the DC/DC converters is a single-stage isolated DC/DC converter,

controlling, by a voltage control, the voltage of the respective DC/DC converters, and

wherein the method further comprises providing a respective predetermined output voltage to a load at each of the plurality of converters of the converting stage.

12. The method according to claim 11 , further comprising:

connecting the power grid to at least one of variable speed heatpump systems, hyperscale datacenters, distributed battery energy storage, physically distributed or collocated DC chargers, and renewable energy sources.

13. The method according to claim 11 , wherein the power grid further comprises a plurality of second DC/DC converters upstream of and connected to each of the plurality of DC/AC converters and at least one switch per second DC/DC converters, the method further comprising:

controlling each of the at least one switch to connect or disconnect outputs of the plurality of second DC/DC converters.

14. The method according to claim 13 , wherein the method further comprises providing a respective predetermined output voltage to a load at each of the plurality of second DC/DC converters.

15. The method according to claim 11 , further comprising:

controlling an input voltage to the power grid to provide a variable DC input to the plurality of DC/DC converters.

16. The method according to claim 15 , wherein controlling the input voltage to the power grid comprises controlling a Modular Multi-Level Converter (MMC) converter.

17. The method according to claim 11 , further comprising:

calculating a number of DC/DC converters per electric vehicle (EV) charger;

for each of the number of DC/DC converters:

calculating a power reference of the DC/DC converters;

calculating a voltage reference of the DC/DC converters; and

distributing DC/DC converter voltage and selecting a switching action for the DC/DC converters.

18. The method according to claim 17 , further comprising:

responsive to an output voltage of one of the number of DC/DC converters operating in a low input DC voltage and having a lows operational efficiency, stopping the one of the number of DC/DC converters from operating.

19. The method according to claim 18 , wherein stopping the one of the number of DC/DC converters from operating comprising closing a bypass breaker associated with the one of the number of DC/DC converters.

Assignments (3)

Priority Claims (2)

Continuity (1)

References Cited (26)