Method and arrangement for improved operability of a high temperature fuel cell system

• US 9,005,832 B2
• Filed: 08/28/2013
• Issued: 04/14/2015
• Est. Priority Date: 02/28/2011
• Status: Active Grant

• Current Assignee: Convion Oy
• Original Assignee: Convion Oy
• Inventors: strm, Kim, Laitinen, Marko
• Primary Examiner(s): Laios, Maria J
• Application Number:
  US14/012,381
• Publication Number:
  US 20140056035A1
• Time in Patent Office: 594 Days
• US Class Current: 429/431
• CPC Class Codes: H01M 2008/1293 Fuel cells with solid oxide electrolytes
• CPC Class Codes: H01M 8/04268 Heating of fuel cells during the start-up of the fuel cells
• CPC Class Codes: H01M 8/04365 of other components of a fuel cell or fuel cell stacks
• CPC Class Codes: H01M 8/04865 Voltage
• CPC Class Codes: H01M 8/0488 of fuel cell stacks
• CPC Class Codes: H01M 8/0491 of fuel cell stacks
• CPC Class Codes: H01M 8/04955 Shut-off or shut-down of fuel cells
• CPC Class Codes: H01M 8/186 by electrolytic decomposition of the electrolytic solution or the formed water product
• CPC Class Codes: H02M 3/33523 with galvanic isolation between input and output of both the power stage and the feedback loop
• CPC Class Codes: Y02E 60/50 Fuel cells

Abstract

An arrangement for improved operability of a high temperature fuel cell device at higher fuel cell voltage values than nominal voltage values, each fuel cell in the fuel cell device including an anode side, a cathode side, and an electrolyte between the anode side and the cathode side, and the arrangement includes means for determining temperature information of the fuel cells and main power converter for loading fuels cells at least up to their rated power level. The arrangement includes a non-isolating pre-regulator for reducing the fuel cell voltage to a voltage level useable for the main power converter at least at substantially low power levels in start-up and low current load situations when the fuel cell voltage is significantly higher than in nominal operation conditions, the pre-regulator being located between the fuel cells and the main power converter, and the arrangement includes bypass means for bypassing the pre-regulator at substantially high current loads when the fuel cell voltage has decreased to the voltage level suitable for an input voltage of the main power converter.

Claims

1. An arrangement for improved operability of a high temperature fuel cell device at higher fuel cell voltage values than nominal voltage values, wherein each fuel cell in the fuel cell device comprises an anode side, a cathode side, and an electrolyte between the anode side and the cathode side, wherein the arrangement comprises:

a main power converter for loading fuel cells at least up to their rated power level, the main power converter comprising galvanic isolation,

a non-isolating pre-regulator for reducing the fuel cell voltage to a voltage level useable with the main power converter at least at substantially low power levels in start-up and low current load situations when the fuel cell voltage is substantially higher than in nominal operation conditions, said pre-regulator being located between the fuel cells and the main power converter, and said pre-regulator being dimensioned for partial load current, and

bypass means for bypassing the pre-regulator at substantially high current loads when the fuel cell voltage has decreased to the voltage level suitable for an input voltage of the main power converter.

2. The arrangement according to claim 1, wherein the maximum allowed input voltage of the main power converter is less than the maximum fuel cell voltage.

3. The arrangement according to claim 1, wherein the maximum allowed current of the pre-regulator is less than 50% of the rated current of the fuel cells.

4. The arrangement according to claim 1, wherein the bypass means comprise a relay mechanism for switching operations for changing the operation mode of the bypass means.

5. The arrangement according to claim 1, wherein the main power converter comprises means for performing a bi-directional power flow.

6. The arrangement according to claim 1, wherein the arrangement comprises the pre-regulator for boost mode of operation in which an electrolysis current is injected to the fuel cells.

8. A fuel cell device, comprising:

fuel cells, wherein each fuel cell comprises an anode side, a cathode side, and an electrolyte between the anode side and the cathode side, and

the arrangement according to claim 1.

9. The arrangement according to claim 1, wherein the fuel cells are solid oxide fuel cells or molten carbonate fuel cells.

7. An arrangement for improved operability of a high temperature fuel cell device at higher fuel cell voltage values than nominal voltage values, wherein the arrangement comprises:

a fuel cell device comprising a fuel cell, wherein the fuel cell comprises an anode side, a cathode side, and an electrolyte between the anode side and the cathode side,

a main power converter for loading fuel cells at least up to their rated power level, the main power converter comprising galvanic isolation,

a non-isolating pre-regulator for reducing the fuel cell voltage to a voltage level useable with the main power converter at least at substantially low power levels in start-up and low current load situations when the fuel cell voltage is substantially higher than in nominal operation conditions, said pre-regulator being located between the fuel cells and the main power converter, and said pre-regulator being dimensioned for partial load current, and

a mechanism for bypassing the pre-regulator at substantially high current loads when the fuel cell voltage has decreased to the voltage level suitable for an input voltage of the main power converter.

10. A method for improved operability of a high temperature fuel cell device at higher fuel cell voltage values than nominal voltage values, the method comprising:

loading fuel cells at least up to their rated power level by a main power converter, which is galvanically isolated,

arranging a non-isolating pre-regulator between the fuel cells and the main power converter, which pre-regulator is dimensioned for partial load current,

using said pre-regulator to reduce the fuel cell voltage to a voltage level useable by the main power converter at least at substantially low power levels in start-up and low current load situations when the fuel cell voltage is significantly higher than in nominal operation conditions, and

bypassing the pre-regulator at substantially high current loads, when the fuel cell voltage has decreased to a voltage level suitable for an input voltage of the main power converter.

11. The method according to claim 10, wherein the maximum allowed input voltage of the main power converter is less than the maximum fuel cell voltage.

12. The method according to claim 10, wherein the maximum allowed current of the pre-regulator is less than 50% of the rated current of the fuel cells.

13. The method according to claim 10, wherein the bypassing of the pre-regulator is achieved using a relay mechanism for switching operations.

14. The method according to claim 10, wherein a bi-directional power flow is performed by utilizing the main power converter.

15. The method according to claim 10, wherein an electrolysis current is injected to the fuel cells in a boost mode of operation of the pre-regulator.

16. The method according to claim 10, wherein each fuel cell comprises an anode side, a cathode side, and an electrolyte between the anode side and the cathode side.

17. The method according to claim 10, wherein the fuel cells are solid oxide fuel cells or molten carbonate fuel cells.