A circuit and method for detecting disconnection of a fuel cell

Abstract

The present invention proposes a circuit for detecting a fuel cell disconnection. The fuel cell is connected in series in sequence, including a filter capacitor, a sampling resistor, an optocoupler unit, an optocoupler gating unit, a detection resistor, a MOS tube, a MOS control unit, an analog-to-digital conversion unit, and an MCU. The present invention provides a hardware detection circuit for a discrete optocoupler solution for fuel cell voltage detection, which solves the problem of false alarms and missed alarms when only software is used to detect disconnections. The disconnection detection circuit utilizes the characteristic of the optocoupler solution to select a battery channel separately, reducing the device cost and design difficulty of the disconnection detection hardware circuit design; the disconnection detection circuit and method can realize independent judgment of the disconnection of the sampling line, will not be restricted by the disconnection of other sampling lines, and will not cause the detection strategy to be extremely complicated due to the continuous disconnection of multiple sampling lines. The disconnection detection circuit and method provided by the present invention utilize the characteristic that the optocoupler can select a single battery channel, and are low-cost and easy to implement.

Description

Technical Field

[0001] The present invention belongs to the field of new energy batteries, and in particular relates to a circuit and method for detecting disconnection of a fuel cell. Background Art

[0002] Common fuel cell stacks on the market, such as hydrogen fuel cell stacks, are composed of hundreds of single cells connected in series, and the single cell voltage, impedance, etc. of the battery are sampled and detected through a voltage patroller. When the fuel cell is running, if a voltage sampling line is disconnected, the upper and lower battery voltage sampling of this sampling line will be abnormal, which will affect the operation of the fuel cell control system. Although the battery voltage acquisition data is abnormal, the actual battery may be normal. At this time, the system continues to operate without causing further failures. It can be considered to shield the abnormal voltage caused by the disconnection first. Therefore, when a disconnection occurs, it must be detected in time so that the fuel cell system can adopt an appropriate control strategy.

[0003] At present, fuel cell disconnection is detected by voltage patrollers, which have two mainstream solutions: integrated chip type and discrete optocoupler type. Integrated chips can integrate disconnection detection functions based on the two principles of current source method and resistance voltage division method; discrete optocoupler currently uses software to determine whether the voltage acquisition data meets the disconnection characteristics to perform disconnection detection, and there is no dedicated hardware circuit.

[0004] Because the current source method and the resistor voltage divider method are designed based on the disconnection of lithium battery voltage sampling, and the number of lithium battery channels is small, although the discrete optocoupler solution of the fuel cell voltage patroller can also build a discrete circuit to realize the disconnection detection function based on these two principles, due to the large number of fuel cell channels, each channel is equipped with a current source or switch, which will lead to an increase in devices, greatly increasing the cost and design complexity, so no disconnection detection hardware circuit is designed. Due to the lack of hardware detection, disconnection detection is only achieved through software diagnosis, which may cause false alarms, missed alarms and other problems. False alarms are reporting low battery voltage as disconnection, and missed alarms are failure to accurately identify the abnormal disconnection and fail to report it. Summary of the invention

[0005] In view of the problem that the discrete optocoupler voltage patrol device in the prior art may have false alarms or missed alarms due to the lack of a disconnection detection hardware circuit, the present invention provides a disconnection detection circuit and method.

[0006] According to one aspect of the present invention, the present invention provides a circuit for detecting a disconnection of a fuel cell, wherein the fuel cell is sequentially connected in series, and comprises a filter capacitor, a sampling resistor, an optocoupler, an optocoupler gating unit, a detection resistor, a MOS tube, a MOS control unit, an analog-to-digital conversion unit, and an MCU;

[0007] The two ends of the fuel cells connected in series and between two adjacent fuel cells connected in series are each connected to the first end of a sampling resistor, the second end of each sampling resistor is connected to the signal input end of an optocoupler unit, a filter capacitor is connected between the second ends of two adjacent sampling resistors, the control signal output end of each optocoupler gating unit is connected to the control signal input end of an optocoupler unit, and the control signal input end of the optocoupler gating unit is connected to the MCU;

[0008] The analog-to-digital conversion unit is used to convert the input differential analog signal into a digital signal. The D pole and S pole of the MOS tube and the detection resistor are connected in series between the two differential signal input terminals of the analog-to-digital conversion unit. The G pole of the MOS tube is connected to the output terminal of the MOS control unit. The input terminal of the MOS control unit is connected to the MCU. The MOS control unit is used to control the conduction state of the MOS under the control of the MCU. The signal output terminals of the two corresponding optical coupling units of each fuel cell are connected to the two differential signal input terminals of the analog-to-digital conversion unit, and the digital signal output terminal of the analog-to-digital conversion unit is connected to the signal input terminal of the MCU.

[0009] In the circuit for fuel cell disconnection detection of the present invention, for a group of adjacent photocoupler units, the corresponding fuel cells are connected in series to form a battery group, and the signal output end of the photocoupler unit corresponding to the positive end of the battery group and the photocoupler units separated from the photocoupler unit by one are connected to the negative signal input end of the analog-to-digital conversion unit, and the signal output end of the photocoupler unit corresponding to the negative end of the battery group and the photocoupler units separated from the photocoupler unit by one are connected to the positive signal input end of the analog-to-digital conversion unit.

[0010] In the circuit for detecting disconnection of a fuel cell of the present invention, the photocoupler units corresponding to all fuel cells to be detected are connected together as a group of adjacent photocoupler units to the same analog-to-digital conversion unit; or,

[0011] The photocoupler units corresponding to all fuel cells to be detected are divided into a plurality of groups of adjacent photocoupler units, and each group of adjacent photocoupler units is connected to an analog-to-digital conversion unit.

[0012] According to another aspect of the present invention, a method for detecting a fuel cell disconnection provided by the present invention is used in any of the above-mentioned circuits for detecting a fuel cell disconnection, and comprises the following steps:

[0013] The MCU controls the MOS control unit to disconnect the MOS tube, and the circuit performs voltage detection in sequence: the MCU controls the optocoupler unit through the optocoupler selection unit. When measuring a fuel cell channel, the optocoupler connected to the positive and negative electrodes of the fuel cell is turned on, and the fuel cell voltage is transmitted to the analog-to-digital conversion unit, which processes the differential voltage and transmits it to the MCU, and the MCU obtains the fuel cell voltage;

[0014] If the detected fuel cell voltage is normal, the voltage detection is continued. If the detected voltage is abnormal, the MCU controls the MOS control unit to turn on the MOS tube, thereby performing a disconnection detection: the fuel cell n with abnormal voltage is detected. If the voltage detected by the analog-to-digital conversion unit is not 0, it is determined that no disconnection has occurred; if the voltage detected by the analog-to-digital conversion unit is 0, the MCU controls the optocoupler connected to the positive and negative poles of the fuel cell n+1 to be in a conductive state, and the analog-to-digital conversion unit detects the fuel cell n+1. If the voltage detected by the analog-to-digital conversion unit is not 0, it is determined that no disconnection has occurred. If the voltage detected by the analog-to-digital conversion unit is 0, it is determined that the connection line of the fuel cell n close to the pole of the fuel cell n+1 is disconnected.

[0015] In the method for detecting fuel cell disconnection of the present invention, when n is the fuel cell with the largest sequence number, it is directly determined that the connection line of the pole of fuel cell n away from fuel cell n-1 is disconnected.

[0016] In the method for detecting fuel cell disconnection of the present invention, the presence or absence of abnormality in the fuel cell voltage is determined in the following manner: when the fuel cell voltage exceeds a certain range of the average value of all fuel cells, it is determined to be abnormal; when it does not exceed a certain range, it is determined to be normal.

[0017] In general, the above technical solutions conceived by the present invention have beneficial effects compared with the prior art: the present invention provides a hardware detection circuit for a discrete optocoupler solution for fuel cell voltage detection, which solves the problem of false alarms and missed alarms when only relying on software to detect disconnection. The disconnection detection circuit utilizes the characteristic of the optocoupler solution to select the battery channel separately, reducing the device cost and design difficulty of the disconnection detection hardware circuit design; the disconnection detection circuit and method can realize independent judgment of the disconnection of the sampling line, will not be restricted by the disconnection of other sampling lines, and will not cause the detection strategy to be extremely complicated due to the continuous disconnection of multiple sampling lines. The disconnection detection circuit and method provided by the present invention utilize the characteristic that the optocoupler can select a single battery channel, which is low in cost and easy to implement. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 A schematic diagram of an embodiment of a circuit for detecting a disconnection of a fuel cell according to the present invention;

[0019] Figure 2 This is a simplified diagram of the voltage detection mode circuit of the present invention when the line is not disconnected;

[0020] Figure 3 This is a simplified diagram of the voltage detection mode circuit when a line break occurs in the present invention;

[0021] Figure 4 A simplified diagram of the circuit of the disconnection detection mode when the line is not disconnected in the present invention;

[0022] Figure 5 A simplified diagram of a disconnection detection mode circuit when a disconnection occurs in the present invention;

[0023] Figure 6 It is a flow chart of an embodiment of a method for detecting a fuel cell disconnection according to the present invention. DETAILED DESCRIPTION

[0024] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0025] refer to Figure 1 In the circuit for detecting a fuel cell disconnection provided in the embodiment of the present invention, the fuel cells are connected in series in sequence. In this embodiment, three of the fuel cells CELL n-1 、CELL n 、CELL n+1 Including filter capacitors C1, C2 and C3, sampling resistor R n-2 , R n-1 , R n and R n+1 , Optocoupler unit OPT n-2 、OPT n-1 、OPT n and OPT n+1 , optocoupler selection unit, detection resistor R7, MOS tube Q1, MOS control unit, analog-to-digital conversion unit and MCU.

[0026] The two ends of the fuel cell connected in series (i.e. Figure 1 A sampling resistor R is connected to each of the top and bottom ends of the dotted box where the fuel cell is located and between two adjacent fuel cells connected in series. n-2 , R n-1 , R n and R n+1 The first end of each sampling resistor R n-2 , R n-1 , R nand R n+1 The second end is connected to an optocoupler unit OPT n-2 、OPT n-1 、OPT n and OPT n+1 A filter capacitor C1, C2 and C3 are connected between the second ends of two adjacent sampling resistors, the control signal output end of each optocoupler gating unit is connected to the control signal input end of an optocoupler unit, and the control signal input end of the optocoupler gating unit is connected to the MCU.

[0027] It should be understood that the optical coupling unit OPT in the present invention n-2 、OPT n-1 、OPT n and OPT n+1 It is an independent chip. In other embodiments, it can also be implemented by using a chip containing multiple optocoupler units. Since a single optocoupler gating unit uses a chip to control the optocoupler unit, the control quantity of a single chip is prioritized. In actual process, the optocoupler gating unit needs to be implemented jointly by multiple chips.

[0028] The analog-to-digital conversion unit is used to convert the input differential analog signal into a digital signal. The D pole and S pole of the MOS tube and the detection resistor are connected in series between the two differential signal input terminals of the analog-to-digital conversion unit. The G pole of the MOS tube is connected to the output terminal of the MOS control unit. The input terminal of the MOS control unit is connected to the MCU. The MOS control unit is used to control the conduction state of the MOS under the control of the MCU. The signal output terminals of the two corresponding optical coupling units of each fuel cell are connected to the two differential signal input terminals of the analog-to-digital conversion unit, and the digital signal output terminal of the analog-to-digital conversion unit is connected to the signal input terminal of the MCU.

[0029] In this embodiment, all the fuel cells to be detected are connected to the same analog-to-digital conversion unit as a group of adjacent photocoupler units. For the group of adjacent photocoupler units, the corresponding fuel cells are connected in series to form a battery pack. The positive end of the battery pack (i.e. Figure 1 The photocoupler unit corresponding to the top of the dotted line frame where the fuel cell is located) and the signal output end of the photocoupler unit separated by one photocoupler unit are connected to the negative signal input end of the analog-to-digital conversion unit, and the negative electrode end of the battery pack (i.e. Figure 1 The optical coupling unit corresponding to the lower end of the dotted line frame where the fuel cell is located) and the signal output ends of the optical coupling units spaced one from the optical coupling unit are connected to the positive signal input end of the analog-to-digital conversion unit.

[0030] In other embodiments of the present invention, all fuel cells to be detected are divided into multiple groups of adjacent photocoupler units, and each group of adjacent photocoupler units is connected to an analog-to-digital conversion unit, that is, the photocoupler units are divided into multiple groups, each group corresponds to an analog-to-digital conversion unit, a corresponding MOS control unit, a MOS tube and a detection resistor R7.

[0031] In this embodiment, the sampling resistor R n-2 , R n-1 , R n and R n+1 The filter capacitors C1, C2 and C3 are used to filter out the noise in the signal input to the optocoupler; the optocoupler selection unit controls the conduction of the optocoupler unit to achieve the switching of different battery channels; the MOS tube is used to switch the disconnection detection mode and the voltage detection mode; the detection resistor is used for voltage division during disconnection detection; the analog-to-digital conversion unit processes the differential voltage signal and converts it into a digital signal that can be received by the MCU; the MCU processes the collected voltage data and controls the optocoupler selection unit and the MOS control unit at the same time. Among them, the data measured by the analog-to-digital conversion unit, because the two sets of differential signals finally transmitted to the analog-to-digital conversion unit by adjacent fuel cells are inverted, so for the reverse input set (for example, CELL n-1 、CELL n+1 The positive signal is finally input to the inverting input terminal of the analog-to-digital conversion unit, and the negative signal is finally input to the non-inverting input terminal of the analog-to-digital conversion unit. The measurement result needs to be inverted to correctly measure the fuel cell voltage, etc. The inversion operation can be implemented by the analog-to-digital conversion unit during circuit design.

[0032] The circuit working principle of the present invention is as follows:

[0033] The circuit is divided into two modes: voltage detection and disconnection detection. The MOS tube is disconnected during voltage detection and turned on during disconnection detection.

[0034] Voltage detection: The MCU controls the optocoupler unit through the optocoupler selection unit and measures the fuel cell channels one by one. When measuring a battery channel, the optocoupler connected to the positive and negative poles of the piece is turned on, and the battery voltage is transmitted to the analog-to-digital conversion unit input. The analog-to-digital conversion unit processes the differential voltage and transmits it to the MCU.

[0035] Disconnection detection: The MCU controls the MOS tube to conduct through the MOS control unit, and then repeats the above voltage detection steps to collect the battery channel voltage.

[0036] The key to realizing the circuit function is that the circuit can accurately identify the difference between the sampling line being disconnected and not disconnected.

[0037] like Figure 2As shown, when the line is not broken, in the voltage detection mode, the sampling voltage V i+ -V i- and battery voltage V n -V n-1 equal;

[0038] like Figure 3 As shown in the figure, when a line is broken, in the voltage detection mode, one input of the analog-to-digital conversion unit is equivalent to being suspended, and the sampling voltage V i+ -V i- Not equal to the battery voltage V n -V n-1 , but the common-mode difference between the other input and the floating input, which often results in full-scale offset;

[0039] like Figure 4 As shown, when the line is not broken, in the line break detection mode, due to the voltage division between the sampling resistor and the detection resistor, the sampling voltage V i+ -V i- Slightly less than the battery voltage V n -V n-1 , but it will not be 0;

[0040] like Figure 5 As shown in the figure, when a line is broken, in the line break detection mode, the detection resistor is equivalent to connecting the two inputs of the analog-to-digital conversion unit. Since the detection resistor is much smaller than the input impedance of the analog-to-digital conversion unit, the sampling voltage V i+ -V i- is a value very close to 0.

[0041] From the analysis of the above four situations, it can be seen that the disconnection detection circuit can accurately identify the difference between the sampling line being disconnected and not disconnected, thereby realizing the disconnection detection function.

[0042] refer to Figure 6 Based on the above principle, the method for detecting a fuel cell disconnection provided by the present invention comprises the following steps:

[0043] The MCU controls the MOS control unit to disconnect the MOS tube, and the circuit performs voltage detection in sequence: the MCU controls the optocoupler unit through the optocoupler selection unit. When measuring a fuel cell channel, the optocoupler connected to the positive and negative electrodes of the fuel cell is turned on, and the fuel cell voltage is transmitted to the analog-to-digital conversion unit, which processes the differential voltage and transmits it to the MCU, and the MCU obtains the fuel cell voltage;

[0044] If the detected fuel cell voltage is normal, the voltage detection is continued. If the detected voltage is abnormal, for example, the CELLn channel voltage deviates from the average voltage of all fuel cells by 200mV (in other embodiments, other methods may also be used, such as using the average voltage of some fuel cells instead of the aforementioned average voltage of all fuel cells), the MCU controls the MOS control unit to turn on the MOS tube, thereby performing a disconnection detection: the fuel cell n with abnormal voltage is detected. If the voltage detected by the analog-to-digital conversion unit is not 0, it is determined that no disconnection has occurred; if the voltage detected by the analog-to-digital conversion unit is 0, the MCU controls the optical coupler connected to the positive and negative poles of the fuel cell n+1 to be in a conducting state, and the analog-to-digital conversion unit detects the fuel cell n+1. If the voltage detected by the analog-to-digital conversion unit is not 0, it is determined that no disconnection has occurred. If the voltage detected by the analog-to-digital conversion unit is 0, it is determined that the connection line of the fuel cell n close to the pole of the fuel cell n+1 is disconnected.

[0045] In the method for detecting fuel cell disconnection of the present invention, when n is the fuel cell with the largest sequence number, it is directly determined that the connection line of the pole of fuel cell n away from fuel cell n-1 is disconnected.

[0046] In the method for detecting fuel cell disconnection of the present invention, the presence or absence of abnormality in the fuel cell voltage is determined in the following manner: when the fuel cell voltage exceeds a certain range of the average value of all fuel cells, it is determined to be abnormal; when it does not exceed a certain range, it is determined to be normal.

[0047] The key technical points of the above implementation scheme are as follows:

[0048] The fuel cell disconnection detection circuit connects a MOS tube and a detection resistor in parallel at the input end of the analog-to-digital conversion unit;

[0049] The fuel cell disconnection detection circuit adopts a MOS control unit to control the detection MOS tube, avoiding the problem that the MCU and the MOS tube do not share the same ground.

[0050] This fuel cell disconnection detection circuit uses an optocoupler to divide the battery channel input into two outputs according to odd and even numbers, so that the positive and negative of each battery channel can be selected at the same time;

[0051] The analog-to-digital conversion unit of the fuel cell disconnection detection circuit is powered by positive and negative power supplies, so that both positive and negative inputs can be collected;

[0052] The detection circuit and method need to detect the abnormal voltage channel and the previous channel to determine whether the connection line between two adjacent channels is broken.

[0053] The above is only an exemplary embodiment of the present disclosure, and the scope of the present disclosure cannot be limited thereto. That is, any equivalent changes and modifications made according to the teachings of the present disclosure are still within the scope of the present disclosure. After considering the specification and practicing the disclosure here, those skilled in the art will easily think of the implementation scheme of the present disclosure. This application is intended to cover any modification, use or adaptation of the present disclosure, which follows the general principles of the present disclosure and includes common knowledge or customary technical means in the technical field not recorded in the present disclosure. The description and examples are regarded as exemplary only, and the scope and spirit of the present disclosure are defined by the claims.

[0054] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0055] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

[0056] The above is only an exemplary embodiment of the present disclosure, and the scope of the present disclosure cannot be limited thereto. That is, any equivalent changes and modifications made according to the teachings of the present disclosure are still within the scope of the present disclosure. After considering the specification and practicing the disclosure here, those skilled in the art will easily think of the implementation scheme of the present disclosure. This application is intended to cover any modification, use or adaptation of the present disclosure, which follows the general principles of the present disclosure and includes common knowledge or customary technical means in the technical field not recorded in the present disclosure. The description and examples are regarded as exemplary only, and the scope and spirit of the present disclosure are defined by the claims.

[0057] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0058] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for detecting a fuel cell disconnection, in a circuit for detecting a fuel cell disconnection, the fuel cells are sequentially connected in series, and the circuit for detecting a fuel cell disconnection comprises a filter capacitor, a sampling resistor, an optocoupler unit, an optocoupler gating unit, a detection resistor, a MOS tube, a MOS control unit, an analog-to-digital conversion unit and an MCU; both ends of the series-connected fuel cells and between two adjacent series-connected fuel cells are each connected to a first end of a sampling resistor, the second end of each sampling resistor is connected to a signal input end of an optocoupler unit, a filter capacitor is connected between the second ends of two adjacent sampling resistors, the control signal output end of each optocoupler gating unit is connected to a control signal input end of an optocoupler unit, and the control signal input end of the optocoupler gating unit is connected to the MCU; The analog-to-digital conversion unit is used to convert the input differential analog signal into a digital signal. The D pole and S pole of the MOS tube and the detection resistor are connected in series between the two differential signal input terminals of the analog-to-digital conversion unit. The G pole of the MOS tube is connected to the output terminal of the MOS control unit. The input terminal of the MOS control unit is connected to the MCU. The MOS control unit is used to control the conduction state of the MOS under the control of the MCU. The signal output terminals of the two corresponding optical coupling units of each fuel cell are connected to the two differential signal input terminals of the analog-to-digital conversion unit. The digital signal output terminal of the analog-to-digital conversion unit is connected to the signal input terminal of the MCU. The method for detecting a disconnection of a fuel cell comprises the following steps: The MCU controls the MOS control unit to disconnect the MOS tube, and the circuit performs voltage detection in sequence: the MCU controls the optocoupler unit through the optocoupler selection unit. When measuring a fuel cell channel, the optocoupler connected to the positive and negative electrodes of the fuel cell is turned on, and the fuel cell voltage is transmitted to the analog-to-digital conversion unit, which processes the differential voltage and transmits it to the MCU, and the MCU obtains the fuel cell voltage; If the detected fuel cell voltage is normal, the voltage detection is continued. If the detected voltage is abnormal, the MCU controls the MOS control unit to turn on the MOS tube, thereby performing a disconnection detection: the fuel cell n with abnormal voltage is detected. If the voltage detected by the analog-to-digital conversion unit is not 0, it is determined that no disconnection has occurred; if the voltage detected by the analog-to-digital conversion unit is 0, the MCU controls the optocoupler connected to the positive and negative poles of the fuel cell n+1 to be in a conductive state, and the analog-to-digital conversion unit detects the fuel cell n+1. If the voltage detected by the analog-to-digital conversion unit is not 0, it is determined that no disconnection has occurred. If the voltage detected by the analog-to-digital conversion unit is 0, it is determined that the connection line of the fuel cell n close to the pole of the fuel cell n+1 is disconnected.

2. The method for detecting a fuel cell disconnection according to claim 1, characterized in that: When n is the fuel cell with the largest sequence number, it is directly determined that the connection line of the pole of fuel cell n away from fuel cell n-1 is broken.

3. The method for detecting a fuel cell disconnection according to claim 1, characterized in that: Whether the fuel cell voltage is abnormal is determined in the following manner: when the fuel cell voltage exceeds a certain range of the average value of all fuel cells, it is determined to be abnormal; when it does not exceed a certain range, it is determined to be normal.

4. The method for detecting a fuel cell disconnection according to claim 1, characterized in that: For a group of adjacent photocoupler units, the corresponding fuel cells are connected in series to form a battery group, and the signal output end of the photocoupler unit corresponding to the positive end of the battery group and the photocoupler units separated from the photocoupler unit by one are connected to the negative signal input end of the analog-to-digital conversion unit, and the signal output end of the photocoupler unit corresponding to the negative end of the battery group and the photocoupler units separated from the photocoupler unit by one are connected to the positive signal input end of the analog-to-digital conversion unit.

5. The method for detecting a fuel cell disconnection according to claim 4, characterized in that: All the photocoupler units corresponding to the fuel cells to be detected are connected together as a group of adjacent photocoupler units to the same analog-to-digital conversion unit; or, The photocoupler units corresponding to all fuel cells to be detected are divided into a plurality of groups of adjacent photocoupler units, and each group of adjacent photocoupler units is connected to an analog-to-digital conversion unit.

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