Electric Power Source Arrangement and Method of How to Use It

• US 20100261085A1
• Filed: 04/05/2010
• Published: 10/14/2010
• Est. Priority Date: 04/09/2009
• Status: Active Grant

• Current Assignee: Guangdong Horizon New Energy Technologies Company Limited, Hyzon Motors, Inc. (Horizon Fuel Cell Technologies Pte Ltd)
• Original Assignee: Horizon Fuel Cell Technologies Pte Ltd
• Inventors: Lu, Yong, Jin, Ke, GU, Zhijun
• Granted Patent: US 8,367,258 B2
• Time in Patent Office: Days
• US Class Current: 429/432
• CPC Class Codes: H01M 8/04559 of fuel cell stacks
• CPC Class Codes: H01M 8/0488 of fuel cell stacks
• CPC Class Codes: H01M 8/04955 Shut-off or shut-down of fuel cells
• CPC Class Codes: Y02E 60/50 Fuel cells

Abstract

An electric power source arrangement is described, comprising a fuel cell means (2) having a nominal voltage and a specified voltage-current characteristic, to be connected to a load (1), and comprising a variable DC-DC voltage converter (3), a by-pass branch (11) by-passing the DC-DC voltage converter, a switch (13) alternatively connecting the fuel cell to the DC-DC voltage converter or to the by-pass branch, and a control unit (12) controlling the switch, which control unit (12) comprises a measuring device coupled to the fuel cell means (2) for detecting the operating point thereof and is configured to connect the by-pass branch (11) if the fuel cell means voltage is within a selected range of section (5) of the voltage-current characteristic of the fuel cell means and to disconnect the by-pass branch in the remaining range of sections (4, 6, 7) of said characteristic.

Claims

1. An electric power source arrangement comprising a fuel cell (2) having a nominal voltage and a specified voltage-current characteristic, connected to a load (1) comprising

a variable DC-DC voltage converter (3),

a by-pass branch (11) by-passing the DC-DC voltage converter,

a switch (13) alternatively connecting the fuel cell to the DC-DC voltage converter or to the by-pass branch, and

a control unit (12) controlling the switch, characterized in that the control unit (12) further comprises a measuring device coupled to the fuel cell means (2) for detecting the operating point thereof and is configured to connect the by-pass branch (11) if the fuel cell means voltage is within a selected range of section (5) of the voltage-current characteristic of the fuel cell means and to disconnect the by-pass branch in the remaining range of the sections (4, 6, 7) of said characteristic.

2. An electric power source arrangement according to claim 1, characterized in that the selected range of section (5) of the voltage-current characteristic is the range at both sides of the nominal voltage wherein the voltage difference in dependency of current changes is not more than 25%.

3. An electric power source arrangement according to claim 2, characterized in that the voltage difference is not more than 15%, preferably not more than 5%.

4. An electric power source arrangement according to claim 1, characterized in that said control unit (12), said switch (13), said by-pass branch (11) and said DC-DC voltage converter (3) are integral parts of a single unit.

5. An electric power source arrangement according to claim 4, characterized in that said switch (13) is an electronic switch, preferably a MOSFET or an IGBT.

6. An electric power source arrangement according to claim 4, characterized in that said DC-DC voltage converter (3) is a stabilized closed-loop controlled converter.

7. A method for using a fuel cell having a nominal voltage and a specified voltage-current characteristic further divided into four sections (4, 5, 6, 7) of ranges of voltage-current characteristics, wherein the cell has a variable DC-DC voltage converter (3), a by-pass branch (11) by-passing the DC-DC voltage converter, a switch (13) alternatively connecting the fuel cell to the DC-DC voltage converter or to the by-pass branch, and a control unit (12) controlling the switch, comprising

connecting the fuel cell to the by-pass branch (11) if the fuel cell voltage is within a range of a specified section (5) of the voltage-current characteristic of the fuel cell (2);

and

disconnecting the fuel cell from the by-pass branch (11) if the fuel cell voltage is in one of the other sections (4, 6, 7) of the voltage-current characteristic of the fuel cell (*2).

8. The method according to claim 7, characterized in that the range of section (5) of the voltage-current characteristic is determined to be the range at both sides of the nominal voltage wherein the voltage varies not more than 25% in dependence on current changes.

9. The method according to claim 8, characterized in that the range is determined to be not more than 15%, preferably not more than 5%.

10. A method for using a fuel cell having a nominal voltage and a specified voltage-current characteristic further divided into at least four sections (4, 5, 6, 7) of ranges of voltage-current characteristics, the cell having a variable DC-DC voltage converter (3), a by-pass branch (11) by-passing the DC-DC voltage converter, a switch (13) alternatively connecting the fuel cell to the DC-DC voltage converter or to the by-pass branch, and a control unit (12) controlling the switch, comprising

establishing at least a recovering section (7) and a shutdown section (8);

designating a first voltage-current operational point (9) representing the minimum fuel cell output voltage to be still convertible under continuous operation conditions, this operational point (9) coinciding with the beginning of the recovering section (7);

further designating a second voltage-current operational point (10) representing the point beyond which the shutdown section (8) begins;

wherein the DC-DC voltage converter (3) issues a sub-nominal voltage while the fuel cell is operating within recovering section (7).

11. The method according to claim 10, characterized in that in the recovering section (7) the fuel cell (2) is intermittently switched off and re-started.

12. The method according to claim 11, characterized in that switching off and restarting the fuel cell (2) is controlled by the control unit (12) according to time transpired and/or idle voltage of the fuel cell.

13. The method according to claim 10 characterized in that, if using a DC-DC voltage converter (3) capable of stepping up the voltage between the selected range of section (5) and the recovering range of section (7), an adapting range of section 6) is provided wherein the converter issues the nominal voltage.