KR20100133839A - Fuel cell system - Google Patents

Abstract

PURPOSE: A fuel cell system is provided to drive various driving parts with different driving voltage without a DC-DC converter, and to simplify a structure of a system by eliminating the DC-DC converter. CONSTITUTION: A fuel cell system has a multi stack structure in which a plurality of fuel cell stacks(10,20) are serially connected. An electric wire(11) is branched between the stacks or between cells in a specific stack to drive parts(40,50) with different driving voltage. The end of a serial stack and the branched electric wire are respectively to the driving parts.

Description

Fuel cell system

The present invention relates to a fuel cell system, and more particularly, to a fuel cell system capable of driving a low voltage driving part and a high voltage driving part without a DC-DC converter.

A fuel cell is a kind of power generation device that converts chemical energy of fuel into electric energy by electrochemical reaction in the fuel cell stack without converting it into heat by combustion. It can also be applied to the power supply of electrical / electronic products, especially portable devices.

Examples of such fuel cells include a polymer electrolyte membrane fuel cell (PEMFC), which is most frequently studied as a power source for driving a vehicle, and a membrane electrolyte based on an electrolyte membrane to which hydrogen ions move. Membrane Electrode Assembly (MEA) with a catalytic electrode layer on both sides, and a gas diffusion layer (GDL) that distributes the reactants evenly and delivers the generated energy. And a gasket and fastening mechanism for maintaining the airtightness and proper clamping pressure of the reactor bodies and the coolant, and a bipolar plate for moving the reactor bodies and the coolant.

In the fuel cell, hydrogen as the fuel and oxygen (air) as the oxidant are respectively supplied to the anode and the cathode of the membrane electrode assembly through the flow path of the separator, and the hydrogen is the anode ('fuel electrode' or 'water'). And the oxygen (air) are supplied to the cathode ('air' or 'oxygen', also known as 'reduction electrode').

Supplied to the anode hydrogen is a hydrogen ion (proton, H ⁺⁾ and electrons by the electrode catalyst constructed on both sides of the electrolyte membrane (electron, e ^-) are decomposed into, passed through only the hydrogen ion in the optional electrolyte membrane cation exchange membrane The electrons are transferred to the cathode through the gas diffusion layer and the separation plate which is a conductor.

In the cathode, the hydrogen ions supplied through the electrolyte membrane and the electrons transferred through the separator meet with oxygen in the air supplied to the cathode by the air supply device to generate a reaction. At this time, due to the movement of hydrogen ions, a flow of electrons occurs through an external conductor, and the flow of electrons generates current.

On the other hand, the fuel cell vehicle drives the vehicle by supplying electric power generated from the fuel cell stack to the driving motor, and in addition to the driving motor, various types of accessories such as an air blower, a stack coolant pump, a radiator fan, and a hydrogen recirculation blower are required for driving the fuel cell. Fuel cell stacks are powered by fuel cell stacks and water pumps to cool electrical components.

FIG. 1 is a diagram illustrating an example of a system mounted on a fuel cell bus, and illustrates a system having two multi-stacked structures in which two fuel cell stacks 10 and 20 are connected in series.

In the illustrated configuration, since the two fuel cell stacks 10 and 20 are connected in series, the high voltage driving components 40 such as the driving motor or the water pump for cooling the electric components are driven by the series voltage α of the stack. The low voltage driving components 50 such as an air blower for driving a fuel cell, a hydrogen recirculating blower, a stack cooling water pump, and the like are controlled by the DC-DC converter 30 to lower the driving voltage α of the high voltage driving component 40. drive to (β).

As such, the method of adjusting the supply voltage using the DC-DC converter 30 requires a system in which fuel cell stacks 10 and 20 are connected in series to drive components having different driving voltage ranges in order to increase the overall output. This can be very useful in.

In addition, the use of the DC-DC converter 30 enables a wide range of voltage adjustments to drive various driving components having different driving voltages, and also enables the supply of a fixed voltage through the DC-DC converter. It becomes easy to develop.

However, there are the following problems in a system using a DC-DC converter.

1) Increased system instability and durability issues

DC-DC converter because the high voltage terminal voltage α on the DC-DC converter side varies variably according to the stack current (current ↑, voltage ↓), and the current used by the low voltage driving parts 50 is also very variable. 30 is driven under extremely poor conditions. This increases system instability and increases the likelihood of a single part durability problem.

2) Complex system structure and system price rise

The structure of the system is complicated by the use of the DC-DC converter 30, and the overall system cost increases due to the expensive DC-DC converter.

3) Difficult to change capacity of low voltage driving parts

Since the capacity of the low voltage driving component 50 is determined by the capacity of the DC-DC converter 30, it is difficult to change the capacity of the low voltage driving component.

Therefore, the present invention has been invented to solve the above problems, it is possible to drive a number of driving components with different operating voltages without a DC-DC converter, simplifying the system structure and cost reduction by eliminating the DC-DC converter The present invention aims to provide a fuel cell system having improved system stability and durability.

In order to achieve the above object, the present invention, in a multi-stack structure in which a plurality of fuel cell stacks are connected in series, in order to drive driving components having different driving voltages, between a stack and between cells or cells within a specific stack. And a driving component connected to each of the ends of the series stack and the branched electrical conductor, so that different driving voltages are applied to each driving component from the fuel cell stack. .

In a preferred embodiment, with the electrical leads branched between the stack and the stack, additional electrical leads are branched between cells and cells in a particular stack, and drive components are connected to the further branched electrical leads to fuel A different driving voltage is applied to each driving component from the battery stack.

Further, in the short stack structure having one fuel cell stack, in order to drive driving components having different driving voltages, electric conductors are branched from cells to cells of the stack, and ends of the stacks and the electric conductors. Each driving component is connected to each other, and a different driving voltage is applied to each driving component from the fuel cell stack.

In a preferred embodiment, the electric wire branched from the cell to the cell is characterized in that the branch is connected to the current collector interposed between the cell and the cell.

Accordingly, according to the fuel cell system according to the present invention, the voltage range can be variously changed according to the branch position of the electric conductor and the number of stacked cells, thereby replacing the DC-DC function.

In particular, it is possible to drive a plurality of driving components having different operating voltages without the DC-DC converter, the system structure is simplified, there is an advantage of the efficiency and cost reduction by eliminating the DC-DC converter.

In addition, since the low voltage driving parts are directly supplied with current from the fuel cell stack, system stability and durability are improved.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The present invention relates to a fuel cell system capable of separately driving a low voltage driving part and a high voltage driving part without a DC-DC converter.

2 is a configuration diagram of a fuel cell system according to a preferred embodiment of the present invention, and illustrates a fuel cell system having a multi-stack structure in which two fuel cell stacks are connected in series.

The illustrated embodiment is an example of a configuration in which two fuel cell stacks 10 and 20 are connected in series, but the present invention is not limited to two multi-stack structures, and the technical features of the claims are claimed. The number of stacks connected in series, such as three or four, can be varied without departing from the range.

As shown, in the fuel cell system according to the present invention, the DC-DC converter for adjusting the voltage supplied to the driving component is eliminated, and all the driving components 40 and 50 are all fuel cells without adjusting the voltage of the DC-DC converter. It is driven by being powered directly from the stacks 10 and 20.

At this time, in the multi-stack structure in which the plurality of stacks 10 and 20 are connected in series, power is directly drawn in accordance with the required driving voltage of the driving component in the middle between the stack and the stack.

Referring to the example of FIG. 2, in the state in which the first stack 10 and the second stack 20 are connected in series, the high voltage driving part 40 is the end of the series stack (the '+' end of the second stack). To be driven by the series voltage of the two stacks.

On the other hand, the low voltage driving part 50 is an electric conductor 11 branched between the first and second stacks so as to receive a voltage output between the first and second stacks 10 and 20. Connected to the '+' end of the stack), such that the low voltage driving component 40 is driven only by the voltage of the first stack 10.

If the number of stacks is three or more instead of two, and the driving components (components driven by the power of the fuel cell) should be classified into three or more groups according to the required driving voltage, the stack is outputted according to the required driving voltage. The point between and the stack must be established.

For example, in a system in which three first, second and third stacks are connected in series, if three groups of driving components classified according to driving voltages are to be connected to receive different driving voltages between groups, The group must be electrically connected to the end of the third stack ('+' end) to receive the three series voltages in the stack, and the second group is between the second stack and the third stack to receive the two series voltages in the stack. It should be connected to a branched electrical conductor ('+' end of the second stack), which is driven by the series voltages of the first and second stacks.

In addition, the third group should be connected to an electric conductor (the '+' end of the first snack) branched between the first stack and the second stack so as to receive a voltage of one stack to be driven only by the voltage of the first stack.

Of course, the voltage output of each stack may be changed in consideration of the driving voltage required by the driving component in the plurality of multi-stack structures.

For example, since the unit cells constituting the stack are all connected in series, by adjusting the number of unit cells in each stack, voltage and current outputs can be adjusted for each stack.

In addition, if the response area where the fuel cell reaction occurs in the unit cell is changed from stack to stack, the voltage and current output can be adjusted from stack to stack. In other words, if the area of the flow path (air flow path and hydrogen flow path) of the separator and the area where the MEA is exposed to the flow path are changed for each stack, the voltage and current output can be adjusted for each stack.

As an example of adjusting the reaction area between the stacks as described above, the reaction area of the fuel cell stack (first stack) 10 to which the low voltage driving part 50 is connected is made larger than that of the fuel cell stack 20, which is low voltage driving. It is possible to handle the extra current consumed by the component.

In this way, in order to drive the driving components having different driving voltages, the fuel cell system according to the present invention is configured such that the driving components are directly supplied with the required voltages between the stacks connected in series and the DC-DC converter as in the prior art. No voltage regulation is required.

Meanwhile, FIGS. 3A and 3B are diagrams illustrating the configuration of a fuel cell system according to another exemplary embodiment of the present invention, which shows a configuration in which a voltage output of various ranges is possible by branching between cells in a stack.

Instead of the manner of branching between the stacks as shown in FIG. 2, the manner of branching between cells as shown in FIGS. 3A and 3B is applicable. In other words, it draws power from the middle of a stack.

FIG. 3A illustrates a fuel cell system having a short stack structure, and FIG. 3B illustrates a fuel cell system having a multi stack structure, in which voltages vary according to the number of cells by connecting electrical conductors 14 between cells in the middle of the stack. It is configured to enable output.

4 is a detailed diagram of a stack for outputting power between cells in a stack and cells in the embodiments of FIGS. 3A and 3B. As illustrated, the fuel cell stack 10 is about 1V according to a required output. Unit cells 12 forming an OCV (Open Circuit Voltage) voltage are stacked in series.

Therefore, in the case of branching the electric conductor 14 in the middle of the specific stack 10, that is, between the cell 12 and the cell 12, a wide range of voltage output is possible according to the number of cells.

In order to enable output of current in the middle of the stack 10, a current collector plate 13 is inserted between the cell 12 and the cell 12 in the middle of the stack as shown in FIG. 4. The electrical conductor 14 through which current is output is connected to the current collector 13a.

When the electrical conductors 14 are connected to the current collector plate 13 inserted in the middle of the stack 10 and the driving components 50 are connected to the electrical conductors 14, the voltage required by the driving components is increased. It can be authorized.

At this time, the voltage applied to the driving component 50 through the current collector plate 13 and the electric conductor 14 is determined according to the number of cells connected in series.

In FIG. 3A, the high voltage driving part 40 is electrically connected to the end ('+' end) of the stack 10 to receive a relatively high voltage from the stack, and the low voltage driving part 50 is a current collector plate in the middle of the stack. The low voltage formed in the cells from one end of the stack to the current collector plate is applied to (13) ('+' end) by the electric conductor 14.

Of course, in FIG. 3A, one current collector plate 13 is used, but a plurality of current collector plates are inserted at each position between the cell and the cell in order to drive a plurality of driving components having different driving voltages, and then to each current collector plate. It is possible to connect electrical leads.

In the embodiment of FIG. 3B, the high voltage driving component 30 is connected to the end of the series stack (the '+' end of the second stack) by an electrical conductor to receive a relatively high voltage, and the low voltage driving component 50 is The current collector plate (denoted by reference numeral 13 in FIG. 4) (the '+' end) of one stack 10 and the low voltage applied through the electric conductor 14 connected thereto are configured to be driven.

3A and 3B, even when power is supplied from the middle of the stack, the total number of cells constituting the specific stack and the number of cells connected in series from the specific stack to the current collector plate (the current collector plate may be Related to the position of the cell to be inserted), the reaction area of the cell, etc. can be appropriately set in consideration of the required voltage of the driving component. In this case, the stacks may be different from each other, or may be different from each other before and after the cells based on the current collector plate.

As such, since the driving voltage is configured to receive the required voltage directly in the middle of a specific stack in order to drive the driving components having different driving voltages, the voltage regulation using the DC-DC converter is not required as in the related art.

In addition, although not shown in the drawings, a multi-stacked fuel cell system may be configured to combine a method of receiving power from a stack and a stack (see FIG. 2) and a method of receiving power from a current collector plate (see FIGS. 3A and 3B). It is also possible to carry out.

1 is a configuration diagram showing an example of a system mounted on a conventional fuel cell bus,

2 is a block diagram of a fuel cell system according to a preferred embodiment of the present invention;

3A and 3B are schematic views of a fuel cell system according to another embodiment of the present invention;

4 is a detailed stack diagram for outputting power between cells in a stack and cells in the embodiment of FIGS. 3A and 3B;

<Explanation of symbols for the main parts of the drawings>

10: first stack 11: electric wire

12 cell 13 collector plate

13a: current collector 14: electric wire

20: second stack 30: DC-DC converter

40: high voltage drive part 50: low voltage drive part

Claims (7)

In a multi-stack structure in which a plurality of fuel cell stacks 10 and 20 are connected in series, a cell between the stack 10 and the stack 20 or a cell in a specific stack in order to drive the driving components 40 and 50 having different driving voltages. Electrical conductors 11 and 14 are branched from between 12 and the cell 12, and drive parts 40 and 50 are connected to the ends of the series stack and the branched electrical conductors 11, respectively, to provide a fuel cell stack. And a different driving voltage is applied to each driving component from the fuel cell system. The method according to claim 1, With the electrical conductors 11 branched between the stack 10 and the stack 20, additional electrical conductors 14 branch between the cells 12 and 12 in a particular stack, and the additional A driving component (50) is connected to the electric conductor (14) branched to the fuel cell system, characterized in that different driving voltages are applied to each driving component from the fuel cell stack. The method according to claim 1 or 2, A fuel cell system, characterized in that the electrical conductors (14) branched from between the cell (12) and the cell (12) are connected to and branched from the current collector plate (13) interposed between the cell and the cell. The method according to claim 1, The fuel cell system, characterized in that the reaction area in which the fuel cell reaction of a specific stack in the multi-stack structure is different from the other stacks. The method according to claim 1, In the multi-stack structure, the number of stacked cells of a specific stack is different from the other stacks, the fuel cell system. In a short stack structure having one fuel cell stack 10, in order to drive the driving components 40 and 50 having different driving voltages, the electric conductors 14 are separated from between the cells 12 and 12 in the stack. And branched and connected to the ends of the stack and the electrical conductors (14), respectively, so that different driving voltages are applied to each of the driving components from the fuel cell stack. The method according to claim 6, The electric conductor (14) is characterized in that the fuel cell system, characterized in that the branch is connected to the current collector plate (13) interposed between the cell (12) and the cell.

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