CN201096875Y - Fuel cell current measuring circuit - Google Patents

Abstract

The utility model provides a fuel cell current measuring circuit for measuring the current of the fuel cell, which comprises a measuring device and a loading module. One electrode of the fuel cell is divided into at least two areas which are insulated mutually, at least two areas are respectively connected with the loading module to form at least two branch circuits, the discharge voltage of at least two branch circuits can be adjusted, and the discharge voltage of at least two branch circuits is respectively measured through the measuring device. The multi-circuit adjustable load is adopted in the fuel cell current measuring circuit, to ensure that each area of the fuel cell works at the identical electrical potential, at this time, the density distribution of the measured current and the current of the obtained fuel battery has higher authenticity.

Description

Fuel Cell Current Measurement Circuit

technical field

The utility model relates to the measurement field, in particular to a fuel cell current measurement circuit.

Background technique

A fuel cell is a device that generates electrical energy through a chemical reaction between a fuel and an oxidant. A high-power PEM fuel cell (proton exchange membrane fuel cell) must output a large current, and it is bound to require a single cell of the fuel cell to have a large area. However, under the same production process conditions, the larger the cell area, the less uniform the current density distribution, and the more the performance of the fuel cell decreases. Therefore, it is necessary to use a PEM fuel cell current density distribution measuring device to study the current density distribution of a large-area PEM fuel cell during the discharge process. Battery production process.

The fuel cell current distribution measurement circuit in the prior art generally divides a certain pole of the fuel cell into multiple regions. As shown in Figure 1, the anode of the fuel cell is divided into a first anode area 11, a second anode area 12 and a third anode area 13, and the first anode area 11 is connected to a load module 21 for current measurement by a wire to form a first branch The second anode area 12 is connected to the load module 22 for current measurement by a wire to form a second branch, and the third anode area 13 is connected to a load module 23 for current measurement by a wire to form a third branch. The aforementioned load module 21 , load module 22 and/or load module 23 may be an independent load, or may be the internal resistance of the fuel cell to be tested. The other end of each load module is connected in parallel to the adjustable load module 31, and the adjustable load module 31 is connected to the cathode of the fuel cell to form a discharge circuit. Adjusting the size of the adjustable load module 31 can control the discharge current and discharge voltage of the fuel cell. The measuring device 40 is used to measure the discharge current and discharge voltage of each anode region, so as to obtain the current distribution of each anode region of the fuel cell under different discharge voltage values, and then calculate the current density of each anode region according to the area of each anode region . Using the existing technology to measure the current distribution of the fuel cell, due to the influence of the load module of each branch or the internal resistance of the fuel cell to be tested, the discharge voltage of the fuel cell in each branch may be different, and the load module of each branch only It can be adjusted uniformly through the adjustable load module 31, but the discharge voltage of each branch fuel cell cannot be adjusted separately. At this time, the measured current of each branch is based on different discharge voltages, which causes a large deviation in the measurement.

Contents of the invention

The utility model provides a fuel cell current measurement circuit, which can more accurately measure the current of the fuel cell and then measure the current density.

The utility model provides a fuel cell current measuring circuit, which measures the current of the fuel cell, including a measuring device and a load module. The modules are connected to form at least two branches, the discharge voltages of the at least two branches are respectively adjustable, and the measuring device respectively measures the discharge currents of the at least two branches.

Preferably, the above-mentioned measuring devices are respectively connected to at least two regions, while the measuring devices are connected to the other pole of the fuel cell.

Preferably, the above-mentioned load module adopts an adjustable load.

Preferably, the above-mentioned load module adopts a sliding rheostat.

Preferably, the above load module is realized by an electronic load circuit.

Preferably, the above-mentioned electronic load circuit adopts LM324 operational amplifier and/or IRFP460 field effect transistor.

Preferably, the above-mentioned fuel cell current measurement circuit further includes a load controller connected between the measurement device and the load module, and adjusts the load module according to the discharge voltage.

Preferably, the above-mentioned fuel cell current measurement circuit further includes a boosted DC power supply.

The utility model adopts multi-channel adjustable loads to make each region of the fuel cell work at the same potential, and the fuel cell current measured by the utility model and the obtained fuel cell current density distribution have higher authenticity.

Description of drawings

Fig. 1 is the circuit structure schematic diagram of the prior art of the utility model;

Fig. 2 is a schematic diagram of the circuit structure of the first embodiment of the utility model;

Fig. 3 is a schematic diagram of the circuit structure of the second embodiment of the utility model;

4 is a schematic diagram of a circuit structure of a third embodiment of the present invention;

Fig. 5 is a schematic circuit diagram of the electronic load in the third embodiment of the present invention.

The realization of the purpose of the utility model, functional characteristics and advantages will be further described in conjunction with the embodiments and with reference to the accompanying drawings.

Detailed ways

Referring to FIG. 2 , it shows a schematic diagram of the circuit structure of the first embodiment of the utility model. The fuel cell current measurement circuit includes a fuel cell 100 , a load module and a measurement device 300 . The anode of the fuel cell 100 is divided into three mutually insulated regions, and each region is connected to a load module to form a branch circuit. As shown in FIG. 2 , the first anode region 101 is connected to the first load module 201 to form a first branch circuit. , the second anode area 102 is connected to the second load module 202 to form a second branch, and the third anode area 103 is connected to the third load module 203 to form a third branch. The other end of the first load module 201 , the other end of the second load module 202 and the other end of the third load module 203 are connected in parallel with each other, and are all connected to the cathode of the fuel cell 100 to form a loop. The measuring device 300 is connected to each region of the anode of the fuel cell 100 , while the measuring device 300 is also connected to the cathode of the fuel cell 100 . The measuring device 300 measures the potential and discharge current of each region of the anode. The first load module 201 , the second load module 202 and the third load module 203 use adjustable loads, preferably, the adjustable loads use sliding rheostats. The measuring device can use a voltmeter to obtain the potential value; configure a sampling resistor or a Hall sensor in each discharge branch to obtain the current value.

The measurement process is as follows: preset a discharge voltage value, and measure the current of the fuel cell 100 under the discharge voltage. Roughly adjust the first load module 201, the second load module 202 and the third load module 203, so that the discharge voltage between the first anode region 101 and the cathode of the fuel cell 100, the discharge voltage between the second anode region 102 and the cathode and The discharge voltage between the third anode region 103 and the cathode is adjusted to be near a preset discharge voltage value. Then fine-tune the first load module 201, the second load module 202 and the third load module 203, so that the potentials at the connection points between the measuring device 300 and the three regions of the anode of the fuel cell 100 are all equal (that is, on the anode of the fuel cell 100 The potential of each region is equal). Then measure the current I1 of the branch where the first anode region 101 is located by the measuring device 300, the current I2 of the branch where the second anode region 102 is located, and the current I3 of the branch where the third anode region 103 is located; establish the first anode region The area of 101 is S1, the area of the second anode region 102 is S2, and the area of the third anode region 103 is S3, then under the current discharge voltage value, the current density of the first anode region 101 is I1/S1, and the area of the second anode region 103 is I1/S1. The current density of the anode region 102 is I2/S2, and the current density of the third anode region 103 is I3/S3. Repeat the above operations, select other discharge voltage values, measure the current of the fuel cell at other discharge voltage values, and calculate the current density based on the area of each anode region, and then obtain the current density distribution result of the fuel cell.

The above-mentioned preset discharge voltage is selected according to the working voltage of the fuel cell 100. The working voltage range of the fuel cell 100 is usually 0.2V-0.8V, and the preset discharge voltage is also selected in the range of 0.2V-0.8V.

Referring to FIG. 3 , it shows a schematic diagram of the circuit structure of the second embodiment of the present invention. The fuel cell current measurement circuit also includes a load controller 400, which is respectively connected to the measuring device 300 and the three load modules, measures the potential and discharge current of each area of the anode according to the measuring device 300, and adjusts the load modules on the corresponding branches. A discharge voltage value is preset before the measurement, and the current density of the fuel cell 100 under the discharge voltage is measured. When the measuring device 300 detects that the discharge voltage between the anode region and the cathode of the fuel cell 100 is greater than the preset discharge voltage value, the load controller 400 reduces the resistance of the load module on the branch where the anode region is located to reduce the discharge voltage, Conversely, when the discharge voltage between the anode region and the cathode of the fuel cell 100 is lower than the preset discharge voltage value, the load controller 400 increases the load resistance on the branch where the anode region is located to increase the discharge voltage. The adjustment of the load resistance by the load controller 400 will cause the discharge voltage to change, and the change of the discharge voltage will cause the load controller 400 to automatically readjust the load resistance according to the feedback from the measurement device 300. When the potentials at the connection points of the three regions of the anode are equal (that is, when the discharge voltages of each region of the fuel cell are equal to the preset discharge voltage value), the fuel cell current measurement circuit reaches a dynamic balance. At this time, the current I1 of the branch where the first anode region 101 is located, the current I2 of the branch where the second anode region 102 is located, and the current I3 of the branch where the third anode region 103 is located are measured by the measuring device 300 . Assuming that the area of the first anode region 101 is S1, the area of the second anode region 102 is S2, and the area of the third anode region 103 is S3, the current density of the first anode region 101 is I1/S1 and the second anode region 102 respectively. The current density is I2/S2, and the current density in the third anode region 103 is I3/S3. Repeat the above operations, respectively measure the current of the fuel cell at other discharge voltage values, and calculate the current density based on the area of each anode region, and then form the result of the current density distribution of the fuel cell.

The selection of the above-mentioned preset discharge voltage is similar to that of the first embodiment, so it will not be described in detail.

Referring to Fig. 4, it shows a schematic diagram of the circuit structure of the third embodiment of the present embodiment. On the basis of the second embodiment, the present embodiment adopts the electronic load circuit to realize the load module, and adopts the microprocessor to realize the load controller 400 and the testing device 300.

Fig. 5 shows a circuit structure of an electronic load circuit, the microprocessor is connected with the inverting input terminal of the operational amplifier U1 through the Vref interface, and provides the voltage control signal Vref for the electronic load circuit; the microprocessor is also connected with the electronic load circuit through the Current interface The current interface of the load is connected to measure the current of each branch. The electronic load circuit is a constant voltage electronic load, which automatically works at a set voltage value according to the voltage control signal Vref of the load controller 400, and the load controller 400 will not intervene in the adjustment process of the constant voltage electronic load. Since the single-cell output voltage of the fuel cell 100 is low, about 1V when open circuited, and the operating voltage range is usually 0.2V-0.8V, it is impossible to make the electronic load composed of transistors work, so this embodiment also includes the fuel cell 100. A step-up DC power supply 500 with cathodes connected in series. The boosted DC power supply 500 increases the potential of the entire fuel cell current measurement circuit to ensure that the electronic load circuit can work normally.

The working principle of the electronic load circuit is as follows: the gate of the transistor Q1 is connected to the output terminal of the operational amplifier U1 through a resistor, that is, the transistor Q1 is driven by the operational amplifier U1, and its on-resistance depends on the output voltage of the operational amplifier U1. The operational amplifier U1 is used as a voltage comparator, its inverting input end is connected to the voltage control signal Vref of the microprocessor, and its non-inverting input end is connected to the discharge voltage of the fuel cell 100 to form a feedback path. When the discharge voltage of the fuel cell 100 is high, Usually, the discharge voltage of the fuel cell 100 is divided by resistors R1 and R6 and then input to the operational amplifier. When measuring, select a discharge voltage value Vref, and measure the current discharge voltage of each region of the fuel cell 100. If the current discharge voltage is greater than Vref, the operational amplifier U1 outputs a high level, and the transistor Q1 is turned on, that is, the load resistance decreases, and the discharge current increases, the discharge voltage of the fuel cell 100 will decrease; if the current discharge voltage of the fuel cell 100 is less than Vref, the operational amplifier U1 outputs a low level, and the transistor Q1 is cut off, that is, the load resistance increases, the discharge current decreases, and the fuel cell 100 The discharge voltage will increase. After multiple comparisons, the discharge voltage signals of each region of the anode as a feedback signal are finally stabilized at Vref, thereby realizing constant voltage discharge. By adjusting the size of Vref, the discharge current can be measured under different discharge voltage values. The microprocessor obtains the current of each branch by measuring the current of the Current interface of the electronic load, and calculates the current density of the fuel cell through the pre-stored area of each anode area, and then forms the result of the distribution of the current density of the fuel cell.

The microprocessor of this embodiment adopts C8051F005, the operational amplifier U1 adopts LM324, and the transistor Q1 adopts power field effect transistor IRFP460. When using an electronic load circuit, the general discharge current is measured through a 0.1 ohm current sampling resistor R7 connected in series.

In the fourth embodiment of the present utility model, the cathode of the fuel cell 100 can also be divided to form a plurality of mutually insulated cathode regions. The fuel cell current measurement circuit and measurement principle are similar to those of the foregoing embodiments, so no further description is given.

The above descriptions are only preferred embodiments of the present utility model, and are not therefore limiting the patent scope of the present utility model. Any equivalent structure or equivalent process transformation made by using the specification of the utility model and the contents of the accompanying drawings may be directly or indirectly used in Other relevant technical fields are all included in the patent protection scope of the present utility model in the same way.

Claims (8)

1. fuel cell current metering circuit, measure the electric current of fuel cell, comprise measurement mechanism and load blocks, one utmost point of described fuel cell is divided into the zone of at least two mutually insulateds, described at least two zones are connected with a load blocks respectively and form at least two branch roads, the sparking voltage of described at least two branch roads is respectively adjustable, and described measurement mechanism is measured the discharge current of described at least two branch roads respectively.

2. fuel cell current metering circuit according to claim 1 is characterized in that, described measurement mechanism is connected with at least two zones respectively, and described measurement mechanism is connected with another utmost point of fuel cell.

3. fuel cell current metering circuit according to claim 1 and 2 is characterized in that, described load blocks adopts tunable load.

4. fuel cell current metering circuit according to claim 3 is characterized in that, described load blocks adopts slide rheostat.

5. fuel cell current metering circuit according to claim 1 and 2 is characterized in that, described load blocks adopts the electronic load circuit to realize.

6. fuel cell current metering circuit according to claim 5 is characterized in that, described electronic load circuit adopts LM324 operational amplifier and/or IRFP460 field effect transistor.

7. fuel cell current metering circuit according to claim 3 is characterized in that, comprises that also load controller, load controller are connected between measurement mechanism and the load blocks, according to sparking voltage regulating load module.

8. fuel cell current metering circuit according to claim 3 is characterized in that, also comprises the voltage boosting dc power supply.

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