Energy storage system and method for increasing the efficiency of an energy storage system

Patent metadata

Field	Value
Publication number	US-10250054-B2
Application number	US-201615208965-A
Country	US
Kind code	B2
Filing date	Jul 13, 2016
Priority date	Jan 17, 2014
Publication date	Apr 2, 2019
Grant date	Apr 2, 2019

Abstract

An energy storage system including an energy store with a plurality of flow batteries, a first voltage converter, an intermediate circuit connected to the first voltage converter, a second voltage converter connected to the intermediate circuit and a first of the batteries, a third voltage converter connected to the intermediate circuit and a second of the batteries, and a controller connected to the first, second, and third voltage converters. The controller is configured to simultaneously control a power flow direction of the second voltage converter and a power flow direction of the third voltage converter such that the power flow direction of the second voltage controller is in an opposite direction of the power flow direction of the third voltage controller, to control a power flow direction of the first voltage controller, and to charge and discharge the batteries.

First claim

What is claimed is:

1. An energy storage system comprising:
an energy store comprising a plurality of flow batteries each of which are connected to a common pair of electrolytes;
an AC/DC-voltage converter configured to be connected to a power grid;
an intermediate circuit connected to a DC-side of the AC/DC-voltage converter;
a first DC/DC-voltage converter connected to the intermediate circuit and connected to at least a first one of the flow batteries;
a second DC/DC-voltage converter connected to the intermediate circuit and connected to at least a second one of the flow batteries; and
a controller connected to the AC/DC-voltage converter, the first DC/DC-voltage converter, and the second DC/DC-voltage converter, wherein the controller is configured to:
simultaneously control a power flow direction of the first DC/DC-voltage converter and a power flow direction of the second DC/DC-voltage converter such that the power flow direction of the first DC/DC-voltage converter is in an opposite direction of the power flow direction of the second DC/DC-voltage converter, and
charge and discharge the flow batteries.

2. The system of claim 1 , wherein the controller is configured to actuate the first DC/DC-voltage converter and the second DC/DC-voltage converter such that energy is conducted from the first one of the flow batteries connected to the first DC/DC-voltage converter to the second one of the flow batteries connected to the second DC/DC-voltage converter.

3. The system of claim 1 , wherein the controller is configured to switch off the AC/DC voltage converter while the first DC/DC-voltage converter and the second DC/DC-voltage converter operate to transfer energy between the first one of the flow batteries and the second one of the flow batteries.

4. An energy storage system arrangement comprising:
a plurality of energy storage systems of claim 1 ; and
a common controller connected to each of the plurality of energy storage systems.

5. A method of increasing energy efficiency of an energy storage system that comprises an intermediate circuit, an AC/DC-voltage converter connected to the intermediate circuit, a first DC/DC-voltage converter connected to the intermediate circuit, a second DC/DC-voltage converter connected to the intermediate circuit, and at least one energy store connected to each of the first DC/DC-voltage converter and the second DC/DC-voltage converter, wherein the at least one energy store connected to the first DC/DC-voltage converter comprises a plurality of flow batteries each of which are connected to a common pair of electrolytes, the method comprising:
controlling, by a controller in communication with the first DC/DC-voltage converter and the second DC/DC voltage controller, a first power flow direction of the first DC/DC-voltage converter in a direction opposite to a second power flow direction of the second DC/DC-voltage converter.

6. The method of claim 5 , wherein energy is transferred between the at least one energy store connected to the AC/DC-voltage converter and the at least one energy store connected to the first DC/DC-voltage converter, and wherein the energy is transferred through the AC/DC-voltage converter, the intermediate circuit, and the first DC/DC-voltage converter.

7. The method of claim 5 , comprising:
transferring energy between the at least one energy store and the second DC/DC-voltage converter through the intermediate circuit and at least one of the AC/DC-voltage converter and the second DC/DC-voltage converter.

8. The method of claim 5 , wherein at least one energy store is completely emptied.

9. An energy storage system comprising:
an AC/DC-voltage converter configured to be connected to a power grid;
an intermediate circuit connected to a DC-side of the AC/DC-voltage converter;
a first DC/DC-voltage converter connected to the intermediate circuit and configured to be connected to a first energy store;
a second DC/DC-voltage converter connected to the intermediate circuit and configured to be connected to a second energy store that comprises at least one flow battery; and
a controller connected to the AC/DC-voltage converter, the first DC/DC-voltage converter, and the second DC/DC-voltage converter, wherein the controller is configured to:
simultaneously control a power flow direction of the first DC/DC-voltage converter and a power flow direction of the second DC/DC-voltage converter such that the power flow direction of the first DC/DC-voltage converter is in an opposite direction of the power flow direction of the second DC/DC-voltage converter, and
start up the at least one flow battery using power from the first energy store.

10. The system of claim 9 , wherein the controller is configured to actuate the first DC/DC-voltage converter and the second DC/DC-voltage converter such that energy is conducted from the first energy store connected to the first DC/DC-voltage converter to the at least one flow battery connected to the second DC/DC-voltage converter.

11. The system of claim 9 , wherein intermediate circuit is configured to operate at a voltage that is ten or more times larger than an operating voltage of the energy store.

12. An energy storage system arrangement comprising:
a plurality of energy storage systems of claim 9 ; and
a common controller connected to each of the plurality of energy storage systems.

13. The system of claim 9 , wherein at least one of the AC/DC voltage converter, the first DC/DC voltage converter, and the second DC/DC voltage converter is a resonant voltage converter.

14. The system of claim 9 , wherein the controller is a self-learning controller that is further configured to charge and discharge the first energy store and the second energy store based on a learned daily current cycle.

15. The system of claim 1 , wherein intermediate circuit is configured to operate at a voltage that is ten or more times larger than an operating voltage of the energy store.

16. The system of claim 1 , wherein at least one of the AC/DC voltage converter, the first DC/DC voltage converter, and the second DC/DC voltage converter is a resonant voltage converter.

17. The system of claim 1 , wherein the controller is a self-learning controller that is further configured to charge and discharge flow batteries based on a learned daily current cycle.

18. The method of claim 5 , wherein the controller is a self-learning controller, the method further comprising charging and discharging the at least one energy store based on a learned daily current cycle.

19. The system of claim 1 , wherein the controller is further configured to start up the flow batteries using a third energy store.

20. The method of claim 5 , further comprising starting up the flow batteries using power from the at least one energy store connected to the second DC/DC-voltage converter.

Assignees

• Trumpf Huettinger Gmbh Co Kg

Inventors

• Lueth Thomas
• Richter Ulrich

Classifications

• H02J7/52

  for charge balancing, e.g. equalisation of charge between batteries · CPC title

• H02J7/865

  Battery or charger load switching, e.g. concurrent charging and load supply (H02J7/50 takes precedence) · CPC title

• H02M3/24

  by static converters · CPC title

• H02J2207/20

  Charging or discharging characterised by the power electronics converter · CPC title

• H02J9/062

  for AC powered loads · CPC title