JPH10223248A - Discharging device for fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform an optimum discharging operation and reduce damages to a cell by electrically dividing a fuel cell into a plurality of sections in serial direction, providing a serial circuit of a discharge resistance and a switch, and a discharge control device in parallel for each section, measuring the voltage within the section by the discharge control device, and opening and closing the switch so that the measured voltage is within a prescribed range. SOLUTION: A semi-block 2 is formed of a plurality of fuel cells 1 connected in series to each other. A serial circuit of a discharge resistance 3 and a switch 4 and a discharge control device 5 are connected in parallel to each semi-block 2. The discharge control device 5 measures the voltage at all times and starts the control of the switch 4, when a preset threshold is detected at the time of operation stop. The voltage in off of the switch 4 is reduced as the residual gas within the cell is consumed by the opening and closing operation of the switch 4, and when this voltage becomes a prescribed target voltage, the control of the switch 4 is terminated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION In a fuel cell power generator,
The present invention relates to a discharge device that consumes residual gas in a fuel cell when operation is stopped and prevents the fuel cell from being left at a high potential.

[0002]

2. Description of the Related Art When an operation of a fuel cell power generation device is stopped, a discharge current is adjusted in order to suppress damage to a catalyst due to a voltage generated by a residual gas in the fuel cell and corrosion of an electrode due to excessive discharge current. , The voltage must be kept within a predetermined range. FIG. 2 is a connection diagram of a conventional device. In FIG. 2, a series circuit of a discharge resistor 3 and a switch 4 and a discharge control device 5 are provided between the positive and negative electrodes of one series of the fuel cell 1 to adjust the discharge current and control the fuel cell voltage. Was.

[0003]

In the conventional apparatus,
Since the discharge operation is common to one series of fuel cells, if the characteristics of the cells at the time of discharge vary, corrosion of the electrodes due to excessive current consumption may occur for cells with a fast discharge.
There is a problem that the catalyst is damaged by the high potential for the slow cell.

When the number of cells in series is large, the DC voltage and the discharge current also increase, and the discharge resistance, wiring, and switch also need to have a large capacity and a high withstand voltage. It was also a factor that hindered. An object of the present invention is to solve these problems, perform an optimal discharge operation, and reduce damage to cells.

[0005]

In order to solve the above-mentioned problems, one series fuel cell is electrically divided into a plurality of sections (semi-blocks), and a discharge resistor and a switch are connected in parallel to each semi-block. And a discharge control device. Each discharge control device measures the voltage in the semi-block and controls the voltage by opening and closing a switch so that the voltage falls within a predetermined range.

By the above means, the discharge device of each semi-block can perform the discharge operation independently without being affected by the discharge operations of the other semi-blocks. Further, since the entire DC voltage is shared by the respective semi-blocks, the discharge resistance, the capacity of the wiring and the switch, and the withstand voltage can be reduced.

[0007]

FIG. 1 is a connection diagram of an embodiment of the present invention. In FIG. 1, a semi-block 2 is configured by stacking a plurality of fuel cells 1 and connecting them in series.
A series circuit of a discharge resistor 3 and a switch 4 and a discharge control device 5 are connected to each semi-block 2 in parallel. The switch 4 performs an opening and closing operation according to a signal from the discharge control device 5.

FIG. 2 is an explanatory diagram of the discharging operation started when the operation is stopped. E ₀ is the voltage of the fuel cell during operation,
E ₁ represents a voltage when voltage at the time of operation stop, the load current the voltage drop due to the internal resistance of the battery by becomes zero is zero. E ₂ represents a target voltage after discharge. The discharge control device 5 is measured continuously voltage, it starts controlling the switch 4 detects a preset threshold (voltage) E _1. As the residual gas in the battery is consumed by the opening and closing operation of the switch 4, the voltage when the switch 4 is turned off decreases, and when the voltage reaches a predetermined target voltage, the control of the switch 4 ends.

[0009]

According to the present invention, even if there is a large variation in the characteristics of the fuel cells, the discharge control is performed for each semi-block, so that the discharge operation can be performed according to the characteristics. Damage can be reduced.

[Brief description of the drawings]

FIG. 1 is a connection diagram showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a discharging operation.

FIG. 3 is a connection diagram showing a conventional device.

[Explanation of symbols]

1 ... fuel cell, 2 ... semi-block, 3 ... discharge resistance,
4 switches, 5 discharge control device.

Claims (1)

[Claims] In a fuel cell comprising a plurality of fuel cells connected in series, the fuel cell is electrically divided into a plurality of sections in the series direction, and each section includes a series connection of a discharge resistor and a switch. A circuit and a discharge control device are connected in parallel with the fuel cell of each section, and the discharge control device measures the voltage of the section and performs opening / closing control of the switch so that the voltage falls within a predetermined range. A discharge device for a fuel cell.