Fuel cell discharge device for preventing high potential of stack at time of vehicle sudden stop

Abstract

The application provides a fuel cell discharge device for preventing high potential of an electric pile when a vehicle is suddenly stopped, and belongs to the technical field of fuel cells, and solves the problem that technology cannot rapidly and effectively discharge when a vehicle is suddenly stopped. The device comprises a capacity resistance circuit, a selection control circuit, a discharge circuit and a controller. The positive pole of the electric pile is connected with the input end of the capacity resistance circuit and the input end of the discharge circuit respectively, and the negative pole is connected with the output end of the capacity resistance circuit and the output end of the discharge circuit respectively. The input end of the selection control circuit is connected with the output end of the controller, and the selection control circuit has two independent selection branches. The output end of the branch one is connected with the control end of the capacity resistance circuit, and the output end of the branch two is connected with the control end of the discharge circuit. The controller is used for selecting the branch one in the selection control circuit to maintain the high potential output of the electric pile when the fuel cell is normally used, and selecting the branch two in the selection control circuit to rapidly discharge the electric pile when the vehicle is suddenly stopped.

Description

Technical Field

[0001] This invention relates to the field of fuel cell technology, and in particular to a fuel cell discharge device that prevents the fuel cell stack from reaching a high potential during a vehicle's emergency stop.

[0002] Background Technology: When fuel cell systems are used in vehicles, an emergency stop of the vehicle can cause a loss of high and low voltage power. At this time, the fuel cell stack is at a high potential, which seriously damages the lifespan of the fuel cell stack. Summary of the Invention

[0003] Based on the above analysis, the present invention aims to provide a fuel cell discharge device that prevents the fuel cell stack from reaching a high potential during a vehicle emergency stop, thereby solving the problem that the prior art cannot discharge quickly and effectively during a vehicle emergency stop.

[0004] On one hand, embodiments of the present invention provide a fuel cell discharge device to prevent high potential of the fuel cell stack during emergency vehicle stops, including a capacitive-resistive circuit, a selection control circuit, a discharge circuit, and a controller; wherein,

[0005] The positive terminal of the fuel cell stack is connected to the input terminal of the capacitive-resistive circuit and the input terminal of the discharge circuit, respectively, and the negative terminal is connected to the output terminal of the capacitive-resistive circuit and the output terminal of the discharge circuit, respectively.

[0006] The input terminal of the selection control circuit is connected to the output terminal of the controller. It has two independent selection branches. The output terminal of branch one is connected to the control terminal of the capacitive resistor circuit, and the output terminal of branch two is connected to the control terminal of the discharge circuit.

[0007] The controller is used to control the selection circuit to turn on branch one and turn off branch two during normal use of the fuel cell to maintain the high potential output of the stack, and to turn off branch one and turn on branch two during emergency stop of the vehicle to discharge the stack.

[0008] The beneficial effects of the above technical solution are as follows: During an emergency stop of the fuel cell, the discharge circuit designed in the DC-DC converter draws power from the fuel cell stack and then selects the discharge branch through the selection control circuit to discharge, preventing the fuel cell stack from being at a high potential and affecting its lifespan. Under normal fuel cell operation, the discharge circuit is shut off by the selection control circuit to avoid power loss, improve system efficiency, and activate the capacitive-resistive circuit to ensure the fuel cell stack is at the high potential required after the vehicle is normally powered on.

[0009] Based on further improvements to the aforementioned device, the capacitive-resistive circuit further includes a resistor R1, a diode D1, and a capacitor C1 connected in sequence; wherein,

[0010] Outside the capacitive-resistive circuit, one end of resistor R1 serves as the input terminal of the capacitive-resistive circuit and is connected to the positive terminal of the fuel cell stack and the input terminal of the discharge circuit, respectively; one end of capacitor C1 serves as the output terminal of the capacitive-resistive circuit and is connected to the negative terminal of the fuel cell stack and the output terminal of the discharge circuit, respectively.

[0011] In the capacitive-resistive circuit, the connection point between diode D1 and capacitor C1 is configured with the control terminal of the capacitive-resistive circuit, which is connected to the output terminal of branch one in the selection control circuit.

[0012] Furthermore, the capacitive-resistive circuit also includes a Zener diode D2; wherein,

[0013] Zener diode D2 is used to provide overvoltage protection for capacitor C1, and it is connected in parallel with capacitor C1.

[0014] Furthermore, the discharge circuit further includes a resistor R6 and a discharge control element Q4 connected in sequence; wherein,

[0015] Outside the discharge circuit, one end of resistor R6 serves as the input terminal of the discharge circuit, and is connected to the positive terminal of the fuel cell stack and the input terminal of the capacitive-resistive circuit, respectively; the source of discharge control element Q4 serves as the output terminal of the discharge circuit, and is connected to the negative terminal of the fuel cell stack and the output terminal of the capacitive-resistive circuit, respectively.

[0016] In the discharge circuit, the connection between resistor R6 and discharge control element Q4 is provided with the control terminal of the discharge circuit, which is connected to the output terminal of branch two in the selection control circuit.

[0017] Furthermore, the discharge control element Q4 is a solid-state relay, an N-type field-effect transistor or an insulated-gate bipolar transistor, or two or more N-type field-effect transistors or two or more insulated-gate bipolar transistors connected in parallel.

[0018] Furthermore, the selection control circuit further includes resistors R2, R4, and R5, N-type transistor Q1, N-type transistor Q2, and P-type transistor Q3; wherein,

[0019] The gate of the N-type transistor Q1 serves as the input terminal of the selection control circuit and is connected to the output terminal of the controller. Its drain is connected to one end of the resistor R2, the gate of the N-type transistor Q2, and the gate of the P-type transistor Q3, respectively. Its source is connected to the source of the P-type transistor Q3, the source of the discharge control element Q4, and the negative terminal of the stack, respectively.

[0020] The other end of resistor R2 serves as the output terminal of branch one in the selection control circuit, and is connected to the control terminal of the capacitive-resistive circuit and the drain of N-type transistor Q2, respectively; the source of N-type transistor Q2 is connected to the drain of P-type transistor Q3 and one end of resistor R4, respectively.

[0021] The other end of resistor R4 serves as the output terminal of branch two in the selection control circuit, is connected to the gate of discharge control element Q4, and is connected to the negative terminal of the fuel cell stack via resistor R5.

[0022] Furthermore, the selection control circuit also includes a resistor R3; wherein,

[0023] The gate of the N-type transistor Q1 is connected to the output of the controller via resistor R3.

[0024] Furthermore, the selection control circuit also includes a light-emitting diode D3; and,

[0025] The N-type transistor Q1 is a phototransistor, and its gate is coupled to the output terminal of the controller via a light-emitting diode D3 and a resistor R3 in sequence.

[0026] Furthermore, the fuel cell stack includes at least one of a proton exchange membrane fuel cell, a solid oxide fuel cell, an alkaline fuel cell, or a methanol fuel cell.

[0027] Preferably, the controller executes the following program:

[0028] The subroutine for charging capacitor C1 after the fuel cell is normally powered on at low voltage includes: when the fuel cell is normally powered on at low voltage, controlling N-type transistor Q1 to turn on so that P-type transistor Q3 turns on synchronously, and discharging control element Q4 to turn off, thereby realizing the start of capacitive-resistive circuit and disconnection of discharge circuit, and the fuel cell charging capacitor C1 through resistor R1 and diode D1; after recognizing that capacitor C1 is fully charged, controlling N-type transistor Q1 to turn off.

[0029] The subroutine for rapidly discharging the fuel cell during an emergency stop of the vehicle includes: after recognizing an emergency stop of the fuel cell, controlling the N-type transistor Q1 to turn off, so that capacitor C1 turns on the N-type transistor Q2 through resistor R2, and discharge control element Q4 is turned on simultaneously. The fuel cell discharges through resistor R6 and discharge control element Q4. After the discharge is completed, discharge control element Q4 is automatically turned off.

[0030] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0031] 1. When the fuel cell is normally powered by low voltage, the N-type transistor Q1 is turned on, causing the P-type transistor Q3 to turn on synchronously. The discharge control element Q4 is turned off, thus starting the capacitive-resistive circuit and disconnecting the discharge circuit. The fuel cell charges the capacitor C1 through the resistor R1 and the diode D1. Because the discharge circuit is disconnected, the system power loss is reduced, and the system efficiency is improved.

[0032] 2. When the vehicle stops suddenly, the N-type transistor Q1 is turned off, causing capacitor C1 to turn on the N-type transistor Q2 through resistor R2. Simultaneously, the discharge control element Q4 is turned on, and the fuel cell discharges through resistor R6 and discharge control element Q4. After discharge is complete, discharge control element Q4 automatically turns off. In the event of an emergency stop, the residual hydrogen in the fuel cell stack is consumed through the discharge circuit, preventing high potential in the stack and improving stack lifespan.

[0033] The summary section is provided to present the chosen concepts in a simplified form, which will be further described in the detailed description below. The summary section is not intended to identify essential or necessary features of this disclosure, nor is it intended to limit the scope of this disclosure. Attached Figure Description

[0034] The above and other objects, features and advantages of this disclosure will become more apparent from the accompanying drawings, in which like reference numerals generally denote like parts.

[0035] Figure 1 A schematic diagram of the composition of the fuel cell discharge device of Example 1 is shown;

[0036] Figure 2 A circuit connection diagram of the fuel cell discharge device of Example 2 is shown.

[0037] Figure label:

[0038] FC - Battery stack; R1, R2, R3, R4, R5, R6 - Resistors R1, R2, R3, R4, R5, R6; C1 - Capacitor C1; D1 - Diode D1;

[0039] D2 - Zener diode D2; D3 - Light-emitting diode D3; Q1 - N-type transistor Q1;

[0040] Q2 - N-type transistor Q2; Q3 - P-type transistor Q3; Q4 - Discharge control element Q4. Detailed Implementation

[0041] Embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the present disclosure will be thorough and complete, and will fully convey the scope of the present disclosure to those skilled in the art.

[0042] The term "comprising" and its variations as used herein signify open inclusion, i.e., "including but not limited to". Unless otherwise stated, the term "or" means "and / or". The term "based on" means "at least partially based on". The terms "one example embodiment" and "one embodiment" mean "at least one example embodiment". The term "another embodiment" means "at least one additional embodiment". The terms "first", "second", etc., may refer to different or the same objects. Other explicit and implicit definitions may also be included below.

[0043] Example 1

[0044] One embodiment of the present invention discloses a fuel cell discharge device that prevents the fuel cell stack from reaching a high potential during a sudden vehicle stop, such as... Figure 1 As shown, it includes a housing and a capacitive-resistive circuit, a selection control circuit, a discharge circuit, and a controller disposed within the housing.

[0045] The positive terminal of the fuel cell stack is connected to the input terminal of the capacitive resistor circuit and the input terminal of the discharge circuit, respectively, while the negative terminal is connected to the output terminal of the capacitive resistor circuit and the output terminal of the discharge circuit, respectively.

[0046] The input terminal of the selection control circuit is connected to the output terminal of the controller. It has two independent selection branches. The output terminal of branch one is connected to the control terminal of the capacitive resistor circuit, and the output terminal of branch two is connected to the control terminal of the discharge circuit.

[0047] The controller is used to control the selection circuit to turn on branch one and turn off branch two during normal use of the fuel cell to maintain the high potential output of the stack, and to turn off branch one and turn on branch two during emergency stop of the vehicle to discharge the stack.

[0048] The capacitive-resistive circuit is a circuit whose main components are a resistor R1 and a capacitor C1 connected in series. Besides the form described in Example 2, the circuit can also be found in existing patents such as CN202011330774.2. The capacitor C1 is used for charging, and its preset charging time is determined by the time constants of the resistor R1 and the capacitor C1. The time required to rise to the high-level state is only on the order of microseconds (μs) to ensure a high potential after the vehicle is powered on normally.

[0049] The selection control circuit is used to select the connection branch of the fuel cell stack-capacitor circuit or the connection branch of the fuel cell stack-discharge circuit. In addition to the form described in Embodiment 2, the circuit can also be the circuit in existing patents such as CN201710711638.X and CN202110942310.5.

[0050] The discharge circuit is a circuit for rapidly discharging the fuel cell stack. Besides the form described in Example 2, the circuit can also be found in existing patents such as CN201520041481.0 and CN201310390870.X.

[0051] During implementation, when the fuel cell is operating normally, the capacitor circuit in the capacitor circuit is quickly charged by selecting the control circuit to ensure a high potential after the vehicle is powered on normally, while the discharge circuit is disconnected to reduce system power loss and improve system efficiency. In the event that the fuel cell stops due to an emergency stop of the vehicle, the residual hydrogen in the stack is consumed by selecting the discharge circuit to avoid a high potential in the stack and improve the stack life.

[0052] Compared with existing technologies, the fuel cell discharge device provided in this embodiment can utilize a discharge circuit designed in the DC-DC converter to draw power from the fuel cell stack during emergency stop of the fuel cell. The discharge branch is then selected via a selection control circuit to prevent the fuel cell stack from being at a high potential, thus avoiding impact on stack lifespan. Under normal fuel cell operation, the discharge circuit is shut off by the selection control circuit to prevent power loss, improve system efficiency, and activate the capacitive-resistive circuit to ensure the fuel cell stack is at the high potential required after the vehicle is normally powered on.

[0053] Example 2

[0054] Based on Embodiment 1, the capacitor-resistor circuit is further improved by including a resistor R1, a diode D1, and a capacitor C1 connected in sequence, as shown below. Figure 2 As shown, but not limited to Figure 2 The range shown. Capacitor C1 can be charged and discharged.

[0055] In this circuit, on the outside of the capacitive-resistive circuit, one end of the resistor R1 serves as the input terminal of the capacitive-resistive circuit and is connected to the positive terminal of the fuel cell stack and the input terminal of the discharge circuit, respectively; one end of the capacitor C1 serves as the output terminal of the capacitive-resistive circuit and is connected to the negative terminal of the fuel cell stack and the output terminal of the discharge circuit, respectively.

[0056] In the capacitive-resistive circuit, the connection point between diode D1 and capacitor C1 is configured with the control terminal of the capacitive-resistive circuit, which is connected to the output terminal of branch one in the selection control circuit.

[0057] Preferably, the capacitive-resistive circuit further includes a Zener diode D2. The Zener diode D2 provides overvoltage protection for capacitor C1 and is connected in parallel with capacitor C1.

[0058] Preferably, the discharge circuit further includes a resistor R6 and a discharge control element Q4 connected in sequence. The discharge control element Q4 is an N-type transistor or a solid-state relay, or a combination of both.

[0059] Existing discharge circuits use a single resistor for discharge, which lacks control and results in high power consumption. In contrast, the discharge circuit in this embodiment automatically controls the discharge through a discharge control element Q4. When discharge is not required, the circuit is shut down, reducing power consumption and improving efficiency. Resistor R6 limits the discharge current, especially in the event of a switch failure, preventing damage to other components.

[0060] In this circuit, on the outside of the discharge circuit, one end of resistor R6 serves as the input terminal of the discharge circuit and is connected to the positive terminal of the fuel cell stack and the input terminal of the capacitive-resistive circuit, respectively; the source of discharge control element Q4 serves as the output terminal of the discharge circuit and is connected to the negative terminal of the fuel cell stack and the output terminal of the capacitive-resistive circuit, respectively.

[0061] In the discharge circuit, the connection between resistor R6 and discharge control element Q4 is provided with the control terminal of the discharge circuit, which is connected to the output terminal of branch two in the selection control circuit.

[0062] Preferably, the discharge control element Q4 can be a solid-state relay, or an N-type transistor (including a MOSFET, an IGBT), or two or more N-type transistors connected in parallel. MOSFET transistors have high input resistance (10 ohms). 8 ~10 9 It has advantages such as low noise, low power consumption, large dynamic range, easy integration, no secondary breakdown phenomenon, and wide safe operating area, which can prevent resistor R6 from overheating. Multiple N-type MOSFET transistors can be connected in parallel.

[0063] Preferably, the selection control circuit further includes resistors R2, R4, and R5, an N-type transistor Q1, an N-type transistor Q2, and a P-type transistor Q3.

[0064] In this circuit, the gate of N-type transistor Q1 serves as the input terminal of the selection control circuit and is connected to the output terminal of the controller. Its drain is connected to one end of resistor R2, the gate of N-type transistor Q2, and the gate of P-type transistor Q3, respectively. Its source is connected to the source of P-type transistor Q3, the source of discharge control element Q4, and the negative terminal of the stack, respectively.

[0065] The other end of resistor R2 serves as the output terminal of branch one in the selection control circuit, and is connected to the control terminal of the capacitive-resistive circuit and the drain of N-type transistor Q2, respectively; the source of N-type transistor Q2 is connected to the drain of P-type transistor Q3 and one end of resistor R4, respectively.

[0066] The other end of resistor R4 serves as the output terminal of branch two in the selection control circuit, connected to the gate of discharge control element Q4, and connected to the negative terminal of the fuel cell stack via resistor R5. Resistors R4 and R5 form a voltage divider circuit to prevent overvoltage damage to discharge control element Q4.

[0067] Through the above circuit structure, capacitor C1 can also automatically supply power to the second branch of the selection control circuit when the vehicle stops suddenly, without the need for power supply from the controller.

[0068] Preferably, the selection control circuit further includes a resistor R3. The gate of the N-type transistor Q1 is connected to the output terminal of the controller via resistor R3.

[0069] Preferably, the selection control circuit further includes a light-emitting diode D3. Furthermore, the N-type transistor Q1 is a phototransistor, and its gate is coupled to the output terminal of the controller via the light-emitting diode D3 and resistor R3 in sequence. The use of optocouplers isolates the input and output of the selection control circuit, ensuring unidirectional electrical signal transmission. This results in excellent electrical insulation and anti-interference capabilities, as well as strong common-mode rejection, preventing false triggering.

[0070] Preferably, the fuel cell stack includes at least one of a proton exchange membrane fuel cell, a solid oxide fuel cell, an alkaline fuel cell, or a methanol fuel cell. Parallel or series configurations are possible, as will be understood by those skilled in the art.

[0071] Preferably, the resistors R1 to R5 can be one of transistor resistors, polysilicon resistors, or N-type well resistors. Furthermore, the capacitor C1 is one of a metal-oxide-semiconductor capacitor, a metal-oxide-semiconductor capacitor, or a metal-insulating layer capacitor.

[0072] Preferably, the controller executes the following program:

[0073] S1. The subroutine for charging capacitor C1 after the fuel cell is normally powered on at low voltage includes: when the fuel cell is normally powered on at low voltage, controlling N-type transistor Q1 to turn on so that P-type transistor Q3 turns on synchronously, and discharge control element Q4 to turn off, thereby realizing the start of capacitive-resistive circuit and disconnection of discharge circuit, and the fuel cell charging capacitor C1 through resistor R1 and diode D1; after recognizing that capacitor C1 is fully charged, controlling N-type transistor Q1 to turn off;

[0074] S2. Subroutine for rapid discharge of fuel cell during vehicle emergency stop, including: after recognizing emergency stop of fuel cell, controlling N-type transistor Q1 to turn off, so that capacitor C1 turns on N-type transistor Q2 through resistor R2, discharge control element Q4 is turned on synchronously, fuel cell discharges through resistor R6 and discharge control element Q4, and discharge control element Q4 is automatically turned off after discharge is completed.

[0075] Compared with the prior art, the discharge device provided in this embodiment has the following beneficial effects:

[0076] 1. When the fuel cell is normally powered by low voltage, the N-type transistor Q1 is turned on, causing the P-type transistor Q3 to turn on synchronously. The discharge control element Q4 is turned off, thus starting the capacitive-resistive circuit and disconnecting the discharge circuit. The fuel cell charges the capacitor C1 through the resistor R1 and the diode D1. Because the discharge circuit is disconnected, the system power loss is reduced, and the system efficiency is improved.

[0077] 2. When the vehicle stops suddenly, the N-type transistor Q1 is turned off, causing capacitor C1 to turn on the N-type transistor Q2 through resistor R2. Simultaneously, the discharge control element Q4 is turned on, and the fuel cell discharges through resistor R6 and discharge control element Q4. After discharge is complete, discharge control element Q4 automatically turns off. In the event of an emergency stop, the residual hydrogen in the fuel cell stack is consumed through the discharge circuit, preventing high potential in the stack and improving stack lifespan.

[0078] The various embodiments of this disclosure have been described above. These descriptions are exemplary and not exhaustive, and are not limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical applications, or improvements to the prior art of the embodiments, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A fuel cell discharge device for preventing high potential of the fuel cell stack during sudden vehicle stop, characterized in that, It includes a capacitor-resistor circuit, a selection control circuit, a discharge circuit, and a controller; among which, The positive terminal of the fuel cell stack is connected to the input terminal of the capacitive-resistive circuit and the input terminal of the discharge circuit, respectively, and the negative terminal is connected to the output terminal of the capacitive-resistive circuit and the output terminal of the discharge circuit, respectively. The input terminal of the selection control circuit is connected to the output terminal of the controller. It has two independent selection branches. The output terminal of branch one is connected to the control terminal of the capacitive resistor circuit, and the output terminal of branch two is connected to the control terminal of the discharge circuit. The controller is used to control the selection circuit to turn on branch one and turn off branch two during normal use of the fuel cell to maintain the high potential output of the stack, and to turn off branch one and turn on branch two during emergency stop of the vehicle to discharge the stack. The capacitive-resistive circuit further includes a resistor R1, a diode D1, and a capacitor C1 connected in sequence; wherein... Outside the capacitive-resistive circuit, one end of resistor R1 serves as the input terminal of the capacitive-resistive circuit and is connected to the positive terminal of the fuel cell stack and the input terminal of the discharge circuit, respectively; one end of capacitor C1 serves as the output terminal of the capacitive-resistive circuit and is connected to the negative terminal of the fuel cell stack and the output terminal of the discharge circuit, respectively. In the capacitive-resistive circuit, the connection point between diode D1 and capacitor C1 is configured with the control terminal of the capacitive-resistive circuit, which is connected to the output terminal of branch one in the selection control circuit.

2. The fuel cell discharge device for preventing high stack potential during vehicle emergency stop according to claim 1, characterized in that, The capacitive-resistive circuit also includes a Zener diode D2; wherein... Zener diode D2 is used to provide overvoltage protection for capacitor C1, and it is connected in parallel with capacitor C1.

3. The fuel cell discharge device for preventing high stack potential during vehicle emergency stop according to claim 2, characterized in that, The discharge circuit further includes a resistor R6 and a discharge control element Q4 connected in sequence; wherein... Outside the discharge circuit, one end of resistor R6 serves as the input terminal of the discharge circuit, and is connected to the positive terminal of the fuel cell stack and the input terminal of the capacitive-resistive circuit, respectively; the source of discharge control element Q4 serves as the output terminal of the discharge circuit, and is connected to the negative terminal of the fuel cell stack and the output terminal of the capacitive-resistive circuit, respectively. In the discharge circuit, the connection between resistor R6 and discharge control element Q4 is provided with the control terminal of the discharge circuit, which is connected to the output terminal of branch two in the selection control circuit.

4. The fuel cell discharge device for preventing high stack potential during vehicle emergency stop according to claim 3, characterized in that, The discharge control element Q4 is a solid-state relay, an N-type field-effect transistor or an insulated-gate bipolar transistor, or two or more N-type field-effect transistors or two or more insulated-gate bipolar transistors connected in parallel.

5. The fuel cell discharge device for preventing high stack potential during vehicle emergency stop according to claim 3 or 4, characterized in that, The selection control circuit further includes resistors R2, R4, and R5, N-type transistor Q1, N-type transistor Q2, and P-type transistor Q3; wherein, The gate of the N-type transistor Q1 serves as the input terminal of the selection control circuit and is connected to the output terminal of the controller. Its drain is connected to one end of the resistor R2, the gate of the N-type transistor Q2, and the gate of the P-type transistor Q3, respectively. Its source is connected to the source of the P-type transistor Q3, the source of the discharge control element Q4, and the negative terminal of the stack, respectively. The other end of resistor R2 serves as the output terminal of branch one in the selection control circuit, and is connected to the control terminal of the capacitive-resistive circuit and the drain of N-type transistor Q2, respectively; the source of N-type transistor Q2 is connected to the drain of P-type transistor Q3 and one end of resistor R4, respectively. The other end of resistor R4 serves as the output terminal of branch two in the selection control circuit, is connected to the gate of discharge control element Q4, and is connected to the negative terminal of the fuel cell stack via resistor R5.

6. The fuel cell discharge device for preventing high stack potential during vehicle emergency stop according to claim 5, characterized in that, The selection control circuit also includes a resistor R3; wherein... The gate of the N-type transistor Q1 is connected to the output of the controller via resistor R3.

7. The fuel cell discharge device for preventing high stack potential during vehicle emergency stop according to claim 6, characterized in that, The selection control circuit also includes a light-emitting diode D3; and... The N-type transistor Q1 is a phototransistor, and its gate is coupled to the output terminal of the controller via a light-emitting diode D3 and a resistor R3 in sequence.

8. The fuel cell discharge device for preventing high stack potential during vehicle emergency stop according to any one of claims 1, 2, 3, 4, 6, and 7, characterized in that, The fuel cell stack includes at least one of the following: proton exchange membrane fuel cell, solid oxide fuel cell, alkaline fuel cell, or methanol fuel cell.

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