Vehicle-mounted fuel cell online activation system and vehicle-mounted fuel cell online activation method

Abstract

The invention discloses a vehicle-mounted fuel cell online activation system, which comprises a fuel cell stack, a main DCDC control circuit electrically connected with the fuel cell stack, and a whole vehicle power system electrically connected with the output end of the main DCDC control circuit, and is characterized in that the main DCDC control circuit is also connected with an activation DCDC circuit in parallel. Meanwhile, the invention also discloses an on-line activation method of the vehicle-mounted fuel cell. The method comprises the following steps: S1, fitting an initial stack voltage curve; s2, a monitoring mode; s3, an online activation mode; and S4, after activating the DCDC circuit to trigger and start for 5-10 minutes, entering the S2 system monitoring mode again, namely circularly alternating the steps S2 and S3 until the S2 immediately monitors that the S3 needs to be started after the S3 is completed, and at the moment, the vehicle-mounted fuel cell needs to be disassembled to be overhauled or scrapped.

Description

Technical Field

[0001] The present invention relates to the technical field of on-vehicle fuel cells, and particularly to an on-vehicle fuel cell online activation system and an on-vehicle fuel cell online activation method. Background Art

[0002] The durability problem of fuel cells has always been a major factor restricting the rapid development of fuel cell vehicles. As the operating time of the fuel cell engine increases, the performance of the fuel cell stack will gradually decay. When the fuel cell stack decays to 80% of its initial performance, it is considered to reach the end of its life.

[0003] The factors causing the decay of the fuel cell stack can be divided into two categories: one is irreversible decay, such as carbon carrier corrosion, catalyst loss, platinum particle growth, proton exchange membrane damage, etc.; the other is reversible decay, and the most important reversible decay is the contamination of the catalyst by impurity gases, such as sulfides and nitrides in the air, and reducing gas impurities in hydrogen. The impurities will react on the catalyst surface, covering the catalyst surface and reducing the reaction area.

[0004] Activation is the main way to solve reversible decay damage, but generally activation is carried out in an offline manner, that is, the fuel cell engine is disassembled and placed on a test bench.

[0005] There is no online activation solution in the prior art. As the operating time of the fuel cell engine increases, the performance decay is serious; the maintenance method for restoring performance requires disassembling the engine and placing it on a test bench for activation, which is difficult to operate, consumes a lot of resources, and has a poor user experience. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide an activation system. The technical solution adopted is: an on-vehicle fuel cell online activation system, which includes a fuel cell stack, a main DCDC control circuit electrically connected to the fuel cell stack, and a vehicle power system electrically connected to the output end of the main DCDC control circuit, characterized in that: an activation DCDC circuit is also connected in parallel to the main DCDC control circuit.

[0007] A further technical feature of the present invention is: The activation DCDC circuit is an R discharge circuit.

[0008] The activation DCDC circuit is an R discharge circuit connected in parallel with a BOOST circuit identical to the main DCDC.

[0009] The present invention also provides an on-vehicle fuel cell online activation method, characterized by including the following steps: S1. Fit the initial stack voltage curve The on-vehicle fuel cell system starts to work and enters the performance self-learning mode at each current density point. The specific operation process is as follows: The system is in the current mode, controlling the main DCDC boost inverter to vary the control current Let the fuel cell system operate at 0.3 A / CM 2 , and record the corresponding stack voltage V1; Let the fuel cell system operate at 0.6 A / CM 2 , and record the corresponding stack voltage V2; Let the fuel cell system operate at 0.9 A / CM 2 , and record the corresponding stack voltage V3; Let the fuel cell system operate at 1.2 A / CM 2 , and record the corresponding stack voltage V4; Let the fuel cell system operate at 1.5 A / CM 2 , and record the corresponding stack voltage V5; Respectively record the stack voltages V1, V2, V3, V4, and V5 at these points, and fit the initial stack voltage curve V = K1*I 3 +K2*I 2 ++K3*I + V0, and record it in the permanent storage unit; S2. Monitoring mode Enable the fuel cell monitoring mode. When the voltage corresponding to a certain monitored current value is compared with the theoretical voltage value obtained from the initial stack voltage curve V = K1*I 3 +K2*I 2 ++K3*I + V0 stored in the permanent storage unit, and is lower than the theoretical voltage value by more than 10%, start the online activation mode; S3. Online activation mode The online activation mode is to trigger and start an activation DCDC circuit in parallel with the on-vehicle fuel cell main DCDC circuit. The activation DCDC circuit outputs an alternating current with a preset amplitude sine wave, thereby causing the stack voltage to fluctuate with the current. The activation duration of the activation DCDC circuit is 5 - 10 minutes; After the activation DCDC circuit is triggered and started for 5 - 10 minutes, enter the S2 system monitoring mode again, that is, steps S2 and S3 alternate in a cycle until S3 is completed and S2 immediately monitors that S3 needs to be started again. At this time, the on-vehicle fuel cell needs to be removed for offline maintenance or scrapped.

[0010] A further technical feature of the present invention is: The activation DCDC circuit is an R discharge circuit.

[0011] The activated DCDC circuit is a parallel combination of an R discharge circuit and a BOOST circuit identical to the main DCDC.

[0012] The beneficial effects of the present invention are as follows: Since the activated DCDC circuit outputs an alternating current with a preset amplitude sine wave, it causes the voltage of the stack to fluctuate with the current. As a result, repeated oxidation and reduction reactions occur on the surface of the fuel cell, enabling the reduction of oxidizing gas impurities and the oxidation of reducing gas impurities on the surface of the catalyst. In this way, the gas impurities on the surface of the catalyst are eliminated, and the catalyst can operate normally without affecting the reaction area, thus playing the role of on-site activation. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a schematic diagram of an embodiment of the present invention; Figure 2 is Figure 1 the activated DCDC circuit diagram in the shown embodiment; Figure 3 is the activated DCDC circuit diagram in another embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0015] The present invention will be further described in detail below with reference to the drawings.

[0016] Referring to Figures 1 to 2 , a vehicle-mounted fuel cell on-line activation system includes a fuel cell stack 1, a main DCDC control circuit 2 electrically connected to the fuel cell stack, and a vehicle power system 4 electrically connected to the output end of the main DCDC control circuit. It is characterized in that: an activated DCDC circuit 3 is also connected in parallel to the main DCDC control circuit 2. In this embodiment, the activated DCDC circuit is as Figure 2 shown as an R discharge circuit.

[0017] In practical applications, the activated DCDC circuit can also be as Figure 3 shown, which is a parallel combination of an R discharge circuit and a BOOST circuit identical to the main DCDC.

[0018] A vehicle-mounted fuel cell on-line activation method is characterized by including the following steps: S1. Fitting the initial stack voltage curve When the vehicle-mounted fuel cell system starts to work, a performance self-learning mode for each current density point is carried out. The specific operation process is as follows: The system is in the current mode, controlling the main DCDC to boost and invert, and varying the control current to make the fuel cell system operate at 0.3 A / CM 2 , and recording the corresponding stack voltage V1; Let the fuel cell system operate at 0.6 A / CM 2 , and record the corresponding stack voltage V2; Let the fuel cell system operate at 0.9 A / CM 2 , and record the corresponding stack voltage V3; Let the fuel cell system operate at 1.2 A / CM 2 , and record the corresponding stack voltage V4; Let the fuel cell system operate at 1.5 A / CM 2 , and record the corresponding stack voltage V5; Respectively record the stack voltages V1, V2, V3, V4, V5 at these points, and fit the initial stack voltage curve V = K1*I 3 +K2*I 2 ++K3*I + V0, and record it into the permanent storage unit; S2. Monitoring mode Enable the fuel cell monitoring mode. When the voltage corresponding to a certain current value during monitoring is compared with the theoretical voltage value obtained from the initial stack voltage curve V = K1*I 3 +K2*I 2 ++K3*I + V0 stored in the permanent storage unit, and when it is lower than the theoretical voltage value by more than 10%, start the online activation mode; S3. Online activation mode The online activation mode is to trigger and start an activation DCDC circuit in parallel with the vehicle-mounted fuel cell main DCDC circuit. In this embodiment, the activation DCDC circuit is as Figure 1 shown, which is an R discharge circuit. When the R discharge circuit works, the K3 relay is pulled in, and at the same time, when the voltage from V4 to the stack voltage V2 is detected and the pre-charging is completed, the K4 relay is pulled in, and the R discharge circuit works. The R discharge circuit discharges the stack, and the R discharge circuit outputs an alternating current with a preset amplitude sine wave, thereby causing the stack voltage to fluctuate with the current. The activation duration of the activation DCDC circuit is 5 - 10 minutes; After the activation DCDC circuit is triggered and started for 5 - 10 minutes, enter the S2 system monitoring mode again, that is, steps S2 and S3 cycle alternately until S3 is completed and S2 immediately monitors that S3 needs to be started again. At this time, the vehicle-mounted fuel cell needs to be removed for offline maintenance or scrapped; In practical applications, the activation DCDC circuit can also be as Figure 2 shown, which is a parallel R discharge circuit and a BOOST circuit same as the main DCDC. The Boost circuit and the R discharge circuit are parallel circuits, as Figure 3As shown, when the Boost circuit is working, first close the K2 relay, and pre-charge the capacitor C1 through the current limiting of R2; detect the voltage V2 to the stack voltage V1. After the pre-charging is completed, close K1, and the BOOST circuit works, and the stack generates electricity; when the R discharge circuit is working, open the K1 and K2 relays, close the K3 relay, and at the same time detect the voltage V4 to the stack voltage V2. After the pre-charging is completed, close the K4 relay, and the R discharge circuit works. Use the R discharge circuit to discharge the stack. The R discharge circuit outputs an alternating current with a sine wave of a preset amplitude, thereby causing the voltage of the stack to fluctuate with the current. The activation DCDC circuit is triggered to start for 5 - 10 minutes.

[0019] In the on-vehicle fuel cell online activation system and the on-vehicle fuel cell online activation method, no matter which activation DCDC circuit, it at least includes an R discharge circuit, which can output an alternating current with a sine wave of a preset amplitude, thereby causing the voltage of the stack to fluctuate with the current, and further causing repeated oxidation reactions and reduction reactions on the surface of the fuel cell, so that the oxidizing gas impurities on the surface of the catalyst are reduced, and the reducing gas impurities are oxidized. In this way, the gas impurities on the surface of the catalyst are eliminated, the catalyst can work normally, and the reaction area is not affected, that is, it plays the role of on-site activation.

[0020] The technical content and technical features of the present invention have been disclosed above. However, it can be understood that under the creative concept of the present invention, those skilled in the art can make various changes and improvements to the above structure, including the combination of the technical features disclosed or claimed here alone, and obviously other combinations of these features. These deformations and / or combinations all fall within the technical field involved in the present invention and fall within the protection scope of the claims of the present invention. The protection scope of the present invention shall be subject to the claims.

Claims

1. An on-vehicle fuel cell online activation system, which comprises a fuel cell stack, a main DCDC control circuit electrically connected to the fuel cell stack, and a vehicle power system electrically connected to the output end of the main DCDC control circuit. Characterized in that: An activation DCDC circuit is also connected in parallel to the main DCDC control circuit.

2. The on-vehicle fuel cell online activation system according to claim 1, Characterized in that: The activation DCDC circuit is an R discharge circuit.

3. The on-vehicle fuel cell online activation system according to claim 1, Characterized in that: The activation DCDC circuit is an R discharge circuit connected in parallel and a BOOST circuit the same as the main DCDC.

4. An on-vehicle fuel cell online activation method, Characterized in that It includes the following steps: S1. Fitting the initial stack voltage curve The on-vehicle fuel cell system starts to work, and performs the performance self-learning mode at each current density point. The specific operation process is: The system is in the current mode, controls the main DCDC to boost and invert, and changes the control current Let the fuel cell system operate at 0.3 A / cm 2 , and record the corresponding stack voltage V1; Operate the fuel cell system at 0.6 A / cm 2 , and record the corresponding stack voltage V2; Let the fuel cell system operate at 0.9 A / cm 2 , and record the corresponding stack voltage V3; Operate the fuel cell system at 1.2 A / cm² 2 , and record the corresponding stack voltage V4; Let the fuel cell system operate at 1.5 A / cm 2 , and record the corresponding stack voltage V5; Record the stack voltages V1, V2, V3, V4, and V5 corresponding to these points respectively, and fit the initial stack voltage curve V = K1*I 3 +K2*I 2 ++K3*I + V0, and record it into the permanent storage unit; S2. Monitoring mode Enable the fuel cell monitoring mode. When the voltage corresponding to a certain current value during operation is compared with the theoretical voltage value obtained from the initial stack voltage curve V = K1*I 3 +K2*I 2 ++K3*I + V0, and when it is lower than the theoretical voltage value by more than 10%, start the online activation mode; S3. Online activation mode The online activation mode is to trigger and start an activation DCDC circuit connected in parallel to the main DCDC circuit of the on-vehicle fuel cell. The activation DCDC circuit outputs an alternating current of a sine wave with a preset amplitude, thereby causing the voltage of the stack to fluctuate with the current. The triggering start duration of the activation DCDC circuit is 5 - 10 minutes; After the activation DCDC circuit is triggered and started for 5 - 10 minutes, it enters the S2 system monitoring mode again, that is, steps S2 and S3 cycle alternately until S3 is completed and S2 immediately monitors that S3 needs to be started again. At this time, the on-vehicle fuel cell needs to be removed for offline maintenance or scrapped.

5. The on-vehicle fuel cell online activation method according to claim 4, Characterized in that The activation DCDC circuit is an R discharge circuit.

6. The on-vehicle fuel cell online activation method according to claim 4, Characterized in that The activation DCDC circuit is an R discharge circuit connected in parallel and a BOOST circuit the same as the main DCDC.

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