JP4291769B2 - Contact detection method - Google Patents

Description

  In particular, the present invention relates to a method for detecting an electrical contact between contacts having an electromotive force.

  A fuel cell is a device that obtains an electromotive force by electrochemically reacting fuel gas and oxygen. Since the electromotive force of each individual cell is only about 1 V at most, it generally has several tens to several hundreds of cells. Used in stacked fuel cell stacks.

  Each cell voltage is measured by means of knowing whether or not each cell constituting the fuel cell stack is in a normal state. If an abnormality occurs in one cell during the operation of the fuel cell, the voltage of that cell will drop significantly. Can be prevented by stopping the battery operation.

In order to detect the voltage from each cell of the fuel cell, for example, as shown in FIG. 7, the separator for separating the cells 102 constituting the fuel cell stack 2 is provided with a protruding voltage measuring terminal 101, and the separator An example of measuring the voltage of the individual cell 102 sandwiched between the two has been reported (see Patent Document 1). In this case, since it is not necessary to make a hole in the end face of the separator, a terminal for voltage measurement is attached even if the fuel cell is small and the cell 102 or the separator is thin, and a lead wire socket is attached thereto. Can be connected to facilitate measurement of the voltage of the individual cell.
However, in actual measurement, the following work of connecting the terminal voltage drawn by the lead wire to the voltage measuring device is further required. Further, in order to connect the lead wire to the terminal, for example, a plurality of needle voltage measuring elements that contact the side surface of the separator of the fuel cell and an urging means for applying an elastic force to the needle voltage measuring elements are provided. Has been reported (see Patent Document 2).
JP 11-339828 A JP 2002-313398 A

However, when there are a large number of cells such as a fuel cell, depending on the usage environment, for example, when used in an electric vehicle, there is still a risk of contact failure due to vibration or the like. It is necessary to verify whether or not the connection is made securely.
When measuring the voltage at multiple measurement points, such as when measuring the cell voltage of a fuel cell, detect whether the connection between the input terminal of the multi-input voltage measurement device and the measurement point is securely performed. However, there have been no examples of accurate and effective contact detection methods reported in the past.
An object of the present invention is to provide a contact detection method for efficiently detecting simultaneously whether or not an input is normally connected from a large number of measurement points by a relatively simple method.

In order to solve the above-mentioned problem, the invention according to claim 1 is characterized in that the connector terminal in a voltage measuring device that measures a potential difference between adjacent connection points of a plurality of electromotive force elements connected in series via a connector terminal. In the contact detection method between the connector terminal and the ground, a plurality of power storage elements provided between the connector terminal and the ground, and charging means for charging the plurality of power storage elements to a predetermined voltage are provided, and the charging means , the voltage whose polarity is inverted with respect to the electromotive force of the electromotive force element, for the electric storage element connected to the electromotive force element of the high-voltage side of the electromotive force element adjacent to the series connection direction, said storage element The absolute value of the voltage is pre- charged with the predetermined voltage different for each power storage element so as to be higher than the voltage of the power storage element connected to the electromotive element on the low voltage side by a predetermined voltage width , connector And it shall be detected by detecting the terminal voltage of the electric storage device that occurs after the said connection point with the child in contact with contact between the connection point and a plurality of the connector terminals at the same time.

According to a second aspect of the present invention, the predetermined voltage is in a negative voltage range, and the electromotive force of the electromotive force element is in a positive voltage range .

  According to a third aspect of the present invention, the storage element is a capacitor of a low-pass filter.

  According to a fourth aspect of the present invention, the plurality of electromotive force elements connected in series are fuel cell cells.

  By doing so, for example, when charging the capacitor as the storage element provided in the input circuit of the voltage measuring device, and measuring the voltage of the electromotive force element by turning on the switch means, the voltage of the capacitor As a result of the change, the contact state between the electromotive force element and the input circuit can be detected, and an effect of being easily detected can be obtained.

Next, embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is an explanatory diagram of a basic circuit for executing the contact detection method of the present invention and its operation. FIG. 2 is a time chart showing the operation and waveform of each part in the circuit of FIG.

  In FIG. 1, symbol C is a battery cell for voltage measurement, symbol Cf is a precharging capacitor, symbol E is an output voltage of a charging circuit for charging the capacitor Cf, symbols SW1a, SW1b, SW2a, and SW2b are switches, symbol R1. , R2 is a resistor, symbol V is a voltage measuring instrument, and symbol GND is ground. This basic circuit operates in the order of FIG. 1A, FIG. 1B, and FIG. 1C to detect contact between a measurement point that is an electrode terminal of a battery cell C that is a voltage measurement target and the voltage measurement circuit. . 2 (a) shows the on / off of the switches SW1a and SW1b, FIG. 2 (b) shows the on / off of the switches SW2a and SW2b, and FIG. 2 (c) shows the terminals of the capacitor Cf when the measurement point contact is normal. FIG. 2D is a waveform showing a change in the terminal voltage of the capacitor Cf when there is no measurement point contact (defective).

The basic operation of the contact detection method of the present invention will be described with reference to FIGS.
First, the switches SW1a, SW1b, SW2a, and SW2b are all opened, and the switches SW1a and SW1b are turned on as shown in FIG. This corresponds to time t1 in FIG. As a result, electricity of the output voltage E flows as a current to the capacitor Cf via the switches SW1a and SW1b, and the capacitor Cf is gradually charged as shown in FIGS. 2 (c) and 2 (d), and finally the terminal of the capacitor Cf. The voltage becomes the output voltage E (V). When charging is completed, the switches SW1a and SW1b are turned off as shown in FIG. This corresponds to time t2 in FIG. In this state, no current flows from the capacitor Cf. Therefore, even if the switches SW1a and SW1b are turned off, the terminal voltage of the capacitor Cf shown in FIG. 2C or 2D is maintained at E (V).

  Next, the switches SW2a and SW2b are turned on as shown in FIG. This corresponds to time t3 in FIG. Thereby, when the contact at the measurement point of the battery cell C, that is, the connection between the battery cell C and the capacitor Cf is normal, a current flows from the battery cell C to the capacitor Cf via the switches SW2a and SW2b. As shown in FIG. 2 (c), the capacitor Cf is gradually charged, and finally the terminal voltage of the capacitor Cf becomes the power generation voltage Vc (V) of the battery cell C. As described above, when the terminal voltage of the capacitor Cf is changed by turning on the switches SW2a and SW2b, the current flows from the battery cell C to the capacitor Cf via the connection of the measurement point and the switches SW2a and SW2b. Therefore, it can be proved that the contact at the measurement point and the operation of the switches SW2a and SW2b are both normal.

  On the other hand, when either the contact at the measurement point or the operation of the switches SW2a and SW2b is not normal and the current does not flow from the battery cell C to the capacitor Cf via the switches SW2a and SW2b, FIG. As shown in d), the terminal voltage of the capacitor Cf does not change and is kept at E (V). Thus, if the terminal voltage of the capacitor Cf does not change even when the switches SW2a and SW2b are turned on, it is considered that no current flows from the battery cell C to the capacitor Cf. It is considered that the operation of either of the switches SW2a and SW2b is not normal.

  The output voltage E is preferably set to a voltage that cannot be taken by the battery cell C during normal operation so that the change in the terminal voltage of the capacitor Cf can be recognized correctly. In addition, when an electric current flows into the battery cell C from the outside, there is an influence such as heat generation inside the battery cell C, which may adversely affect the battery cell C. Therefore, the output voltage E is taken by the battery cell C during operation. It is preferable that the voltage is lower than, for example, a negative voltage.

  Next, an embodiment of the present invention will be described. Although the example of FIG. 1 is an example of a single input, when contact detection is simultaneously performed for a plurality of inputs, special input is required for detection because input voltages from a plurality of battery cells are intertwined.

  FIG. 3 is a circuit diagram showing an input circuit in the voltage measuring device that simultaneously measures the electromotive forces of four battery cells C connected in series at the same time. Next, the contact detection method of the present invention will be described with reference to FIG. This input circuit 10 can detect four voltages of each battery cell. 3, reference characters B1 to B5 are buffers, reference symbols C1 to C4 are battery cells that are voltage measurement targets, reference symbols D1 to D4 are differential amplifiers, F1 to F4 are capacitors that constitute a low-pass filter, and reference symbols S1 to S1. S5 is a photo MOS switch, and GND is a ground. A low-pass filter composed of a capacitor F (F1 to F4) and a resistor is connected to the input terminal of the input circuit 10, removes noise applied when measuring the voltage of the battery cell, and stabilizes the voltage. It has become. The capacitor F is also used for detecting contact between the input circuit 10 and the battery cell. That is, as described above, in this embodiment, when the capacitor F of this low-pass filter is charged in advance, the photo MOS switch is turned on, and each terminal of the input circuit 10 is connected to the battery cell, the photo MOS switch A contact failure between the measurement point of the battery cell C (C1 to C4) and the input terminal is detected by a change in the voltage of the capacitor F (F1 to F4) before and after being turned on.

  Specifically, the capacitors F (F1 to F4) of the low-pass filter are charged to different voltages, the photo MOS switches S (S1 to S5) are turned on, and the voltage change of the capacitor F is confirmed. Simultaneously, the contact between the measurement points of the four battery cells C (C1 to C4) and the input terminals is detected, and the electromotive force of the four battery cells C (C1 to C4) is simultaneously measured by a CPU (not shown). be able to. Further, when the electromotive force measurement of the battery cells C1 to C4 is finished, the photo MOS switches S (S1 to S5) are turned off, and the five photo MOS switches S connected to the next four battery cells are turned on. When the connection is sequentially switched so that each input terminal of the input circuit 10 is switched to the next four battery cells, the voltage of the battery cell can be measured while detecting contact with each measurement point. This is the same as in the prior art and will not be described in detail.

Here, it is assumed that the battery cells C1 to C4 to be measured are the fuel cell 102 as shown in FIG. The electromotive force during operation of the unit cell of the fuel cell is 0V to 1.3V.
FIG. 4 is a diagram showing an input circuit that enables detection of contact with a measurement point based on the principle described above. 4, a charging circuit 11 and switches SW (SW1 to SW4) that can be charged with different voltages are added to capacitors F (F1 to F4), respectively, and symbols C1 to C4 are connected in series. The series electromotive force of the two battery cells is measured and between the output terminals of the buffers B2 to B5 and the positive input terminals of the differential amplifiers D1 to D4. 3 is different from the configuration of FIG. 3 in that a resistor r is connected and 1V is applied to the + input terminals of the differential amplifiers D1 to D4 via the resistor R.

  Next, the contact detection method of the present invention will be described with reference to FIG. First, the photo MOS switches S1 to S5 are turned off, and the switches SW1 to SW4 are turned on. When this is applied to the examples of FIGS. 1 and 2, this corresponds to time t1 in FIG. 2A in which the switches SW2a and SW2b are turned off and the switches SW1a and SW1b are turned on.

At this time, the charging circuit 11 respectively to the capacitor F1~F4 through the switch SW1 to SW4, -0.3 V, -0.6 V, -0.9 V and - charging at the electromotive force of 1.2V. Thereby, each capacitor | condenser F (F1-F4) of a low-pass filter is each charged with a different voltage. When the charging is completed, the output voltages of the differential amplifiers D1 to D4 are all + 0.7V. For example, when the differential amplifier D2 is taken as an example, on the + input side, −0.6V charged in the capacitor F2 is input to the + input terminal of the differential amplifier D2 via the buffer B3 and is offset by + 1V. Is added to the voltage. On the negative input side of the differential amplifier D2, −0.3V charged in the capacitor F2 is input through the buffer B2, and therefore −0.6 + 1 − (− 0.3) = + 0.7 (V). is there. Similarly, a voltage of 0.7 V is output from each of the differential amplifiers D1, D3, and D4. When charging is completed, the switches SW1 to SW4 are turned off. This timing corresponds to time t2 in FIG.

  Then, after the switches SW1 to SW4 are turned off, the photoMOS switches S1 to S5 are turned on (this corresponds to time t3 in FIG. 2B). Thereby, each capacitor | condenser F (F1-F4) is each connected to the corresponding battery cell C1-C4, and is charged with the output voltage.

  Here, it is assumed that the single electromotive forces of the battery cells are all + 1V, and the electromotive forces of the battery cells C1 to C4 are + 2V. When all the contact points of the measurement points are normal and the photoMOS switches S1 to S5 are operating normally, the terminal voltage of the capacitor F1 is changed from −0.3V to + 2V, and the terminal voltage of the capacitor F2 is −0. The terminal voltage of the capacitor F3 changes from -0.9V to + 6V, and the terminal voltage of the capacitor F4 changes from -1.2V to + 8V.

  As a result, +3 V obtained by adding the offset voltage +1 V to the terminal voltage +2 V is applied to the + input terminal of the differential amplifier D1, and 0 V is applied to the − input side. + 5V, which is the sum of + 4V and + 1V, is added to the + input terminal of the differential amplifier D2, + 2V is supplied to the -input side, + 7V is supplied to the + input terminal of the differential amplifier D3, and + 4V is supplied to the -input side. + 9V is applied to the + input terminal of the amplifier D4, and + 6V is applied to the − input side, and the outputs of the differential amplifiers D1 to D4 are all + 3V.

  The electromotive force during operation of the unit cell of the fuel cell is in the range of 0V to + 1.3V, and the electromotive force (output voltage) of the battery cells C1 to C4 in which two unit cells are arranged in series is 0V to + 2.6V. Is in range. Corresponding outputs of the normal differential amplifiers D1 to D4 are in the range of + 1V to + 3.6V as shown in FIG. 5 when the offset voltage is + 1V. Therefore, when the output shows a value other than this, it can be detected that a contact failure at the measurement point or a failure of the photoMOS switches S1 to S5 has occurred.

Next, the identification of a poor contact location will be described.
Table 1 shows the location of occurrence of contact failure or switch failure and the output voltage values of the differential amplifiers D1 to D4 in this embodiment. This table shows a case where the offset voltage is + 1V and the electromotive force of each battery cell is + 2V. How to read this table will be described with reference to an example.

  Here, consider the case where the measurement point AN-0 is defective in FIG. 4, that is, the case where there is a contact failure or disconnection on the negative electrode side of the battery cell C1, or the photoMOS switch S1 is defective. At this time, since the ground GND is not connected to the battery cell C side, the capacitors F (F1 to F4) are not charged from the battery cell C (C1 to C4) side even if other parts are normal, and the maximum in Table 1 is obtained. As shown in the lower row, the outputs of the differential amplifiers D2 to D4 are unstable except that the same + 0.7V is output as when the ground GND is charged from the differential amplifier D1 connected to the negative input terminal.

  Next, in the case of a defect at the measurement point AN-2, that is, there is a contact failure or disconnection at the measurement point on the negative electrode side of the battery cell C3 and the positive electrode side of the battery cell C2, or the photoMOS switch S3 has a defect. Think about the case. In this case, since the capacitor F1 is charged to + 2V, the output of the differential amplifier D1 is + 2 + 1 = 3 (V) as a sum with the offset voltage.

  Since the capacitor F2 is not charged from the battery cell C2 side, it maintains -0.6V, which is the same as when charged. Therefore, −0.6 + 1 = + 0.4 (V) is applied to the + input terminal of the differential amplifier D2, and + 2V is applied to the −input terminal, so that the output of the differential amplifier D2 is + 0.4−2 = −. 1.6 (V).

Similarly, the capacitor F3 is charged to + 6V from the battery cell C3 side, and + 6 + 1 = + 7 (V) is applied to the + input terminal of the differential amplifier D3, and −0.6V is applied to the −input terminal. The output of the dynamic amplifier D2 is +7 − (− 0.6) = + 7.6 (V).
Further, the capacitor F4 is charged to + 8V from the battery cell C4 side, and + 8 + 1 = + 9 (V) is applied to the + input terminal of the differential amplifier D4 and + 6V is applied to the − input terminal. The output is +9 − (+ 6) = + 3 (V). These output voltages are shown in the third column of Table 1. Defects at other locations can be detected in the same way.
By examining the output voltages of the differential amplifiers D1 to D4 as described above, it is possible to detect whether the contact is normal or any location of AN-0 to AN-4, such as a contact failure, disconnection, or switch failure. .

  By the way, conventionally, there are many examples in which filters f1 to f4 as shown in FIG. 6 are used as a low-pass filter for removing such noise, but since each circuit is completely independent, the number of parts is large. Become. In the present invention, as shown in FIG. 3 and FIG. 4, only a resistor and a smoothing capacitor are used, and one end of the smoothing capacitor is dropped to GND. Therefore, the number of circuit elements is reduced by reducing the number of resistance elements. can do.

As described above, the present invention provides an effective method for detecting contact between a connector terminal of a plurality of battery cells connected in series, such as a fuel cell, and the connection point, so that a fuel cell system is widely used. It has the possibility of being widely used in fields where monitoring of such electromotive force elements is necessary, mainly in the industrial field.
Moreover, in this Embodiment, regarding the charging voltage of capacitor | condenser F1-F4, although it charged with the negative voltage which reversed the polarity with respect to battery cell C1-C5, you may charge with a positive voltage.

It is explanatory drawing of the basic circuit which performs the contact detection method of this invention, and its operation | movement. It is a time chart which shows the operation | movement and waveform of each part in the circuit of FIG. It is a circuit diagram of the input circuit of the voltage measuring device which measures the electromotive force of four battery cells connected in series simultaneously using the present invention. It is a figure which shows the input circuit which enabled the detection of the contact with a measuring point based on this invention. It is explanatory drawing which shows the relationship between the starting force (output voltage) of the battery cell of a fuel cell, and the output of a differential amplifier. It is a figure which shows the structure of the filter used for the conventional circuit. It is sectional drawing of a fuel cell.

Explanation of symbols

10 Input Circuit 11 Charging Circuit (Charging Means)
101 voltage measurement terminal 102 cell AN-0 to AN-4 measurement point B2, B3 buffer C battery cell (electromotive force element)
Cf capacitor (storage element)
D1 to D4 Differential amplifier E Output voltage F1 to F4 Capacitor (storage element)
GND Grounding S1-S5 Photo MOS switch

Claims (4)

In the contact detection method between the connector terminal and the connection point in a voltage measuring device that measures the potential difference between adjacent connection points of a plurality of electromotive elements connected in series via the connector terminal,
A plurality of power storage elements provided between the connector terminal and the ground;
Charging means for charging the plurality of power storage elements to a predetermined voltage;
The charging means,
For the storage element connected to the high-voltage side electromotive force element adjacent to the electromotive force element adjacent in the series connection direction at a voltage whose polarity is inverted with respect to the electromotive force of the electromotive force element, the voltage of the storage element Is charged in advance with the predetermined voltage different for each power storage element so that the absolute value is higher than the voltage of the power storage element connected to the electromotive element on the low voltage side by a predetermined voltage width ,
Detects the terminal voltage of the storage element that occurs after the connector terminal and the connection point are in contact with each other
And the contact detection method characterized by detecting simultaneously the contact with the said several connector terminal and the said connection point . The contact detection method according to claim 1, wherein the predetermined voltage is a negative voltage range, and the electromotive force of the electromotive force element is a positive voltage range .   The contact detection method according to claim 1, wherein the power storage element is a capacitor of a low-pass filter. The contact detection method according to claim 1, wherein the plurality of electromotive force elements connected in series are fuel cell cells.

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