Fuel cell series-parallel multi-stack coordinated operation system and control method thereof

Abstract

The present invention discloses a fuel cell series-parallel multi-stack coordinated operation system and a control method thereof, the system comprising a plurality of fuel cell stacks, a gas supply module, a DC / DC converter, a series gas supply circuit, a parallel gas supply circuit, an electrical series circuit, an electrical parallel circuit and a controller. The series gas supply circuit and the electrical series circuit operate in a series operation mode selected by the controller; the parallel gas supply circuit and the electrical parallel circuit operate in a parallel operation mode selected by the controller. The present invention can fully combine the advantages of the series operation and parallel operation of the fuel cell multi-stack system, improve the service life of the fuel cell, and reduce the complexity of the control strategy.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cells, and in particular to a fuel cell series-parallel multi-stack coordinated operation system and a control method thereof. Background Art

[0002] Renewable energy sources such as wind and light have uncontrollable disadvantages. Storing the electricity from new energy sources by electrolyzing water to produce hydrogen is a very good solution. Therefore, countries are vigorously developing hydrogen energy application scenarios. Among them, fuel cells can directly convert the chemical energy of hydrogen into electrical energy through electrochemical reactions. Since they do not go through combustion and are not restricted by the Carnot cycle, they have the significant advantage of high energy conversion efficiency and will be widely used in various mechanical equipment.

[0003] At present, the power of a single proton exchange membrane fuel cell stack is about 100kW, which is generally used in passenger cars and buses. When the power demand increases, there are currently two solutions to increase the output power of the fuel cell. One is to continue to increase the number of single fuel cells and increase the output power of the fuel cell on the basis of a single stack, but this will make the stack assembly more difficult and cause local hot spots to occur frequently. The other is to increase the number of fuel cell stacks and use multiple fuel cell stacks to work together to output the target power.

[0004] Among them, there are two operating modes for the fuel cell multi-stack system: multi-stack series operation and multi-stack parallel operation. Multi-stack series operation has the significant advantages of simple structure and simple control, but its disadvantages are also very obvious: if one fuel cell stack in the system is damaged, the entire system cannot be used, and even when the load power demand is low, the entire system needs to be turned on at the same time. At this time, the fuel cell stack as a whole works at a high potential, which is not conducive to battery life. Multi-stack parallel operation has the advantage of flexible operation. Even if some fuel cell stacks in the system are damaged, the entire system can still operate, but the current multi-stack parallel operation system is equipped with a DC / DC converter for each fuel cell stack, resulting in problems such as complex control strategy, difficult control and high investment cost. Summary of the invention

[0005] The present invention aims to solve the deficiencies in the prior art. An embodiment of the present invention provides a fuel cell series-parallel multi-stack cooperative operation system and a control method thereof, which can fully combine the advantages of series operation and parallel operation of the fuel cell multi-stack system, not only avoiding the adverse operating conditions of high potential caused by the fuel cell multi-stack system when the load is small, and improving the service life of the fuel cell, but also avoiding the complex control strategy caused by the fuel cell multi-stack system when the load is large, reducing the complexity of the control strategy and reducing the system cost.

[0006] In the first aspect, an embodiment of the present invention provides a fuel cell series-parallel multi-stack coordinated operation system, which includes: multiple fuel cell stacks, a gas supply module, a DC / DC converter, a series gas supply circuit, a parallel gas supply circuit, an electrical series circuit, an electrical parallel circuit and a controller; the gas supply module connects the multiple fuel cell stacks in series through the series gas supply circuit; the gas supply module also connects the multiple fuel cell stacks in series through the parallel gas supply circuit; the multiple fuel cell stacks are connected in series with the DC / DC converter through the electrical series circuit; the multiple fuel cell stacks are connected in parallel with the DC / DC converter through the electrical parallel circuit; the series gas supply circuit, the parallel gas supply circuit, the electrical series circuit and the electrical parallel circuit are all connected to the controller; wherein the series gas supply circuit and the electrical series circuit operate in the series working mode selected by the controller; the parallel gas supply circuit and the electrical parallel circuit operate in the parallel working mode selected by the controller.

[0007] Furthermore, the series gas supply circuit is used to transmit the reaction gas provided by the gas supply module to all fuel cell stacks and to discharge the exhaust gas generated by all fuel cell stacks into the atmosphere when the controller selects the series working mode; the parallel gas supply circuit is used to transmit the reaction gas provided by the gas supply module to a preset number of fuel cell stacks and to discharge the exhaust gas generated by the preset number of fuel cell stacks into the atmosphere when the controller selects the parallel working mode; the electrical series circuit is used to transmit the energy generated by all fuel cell stacks in series to the DC / DC converter when the controller selects the series working mode; the electrical parallel circuit is used to transmit the energy generated by the preset number of fuel cell stacks in parallel to the DC / DC converter when the controller selects the parallel working mode.

[0008] Furthermore, a gas series circuit switch valve and a series exhaust gas emission valve are provided on the series gas supply circuit; the gas series circuit switch valve is provided between the gas supply module and the multiple fuel cell stacks, and the series exhaust gas emission valve is provided between the multiple fuel cell stacks and the atmosphere, and the gas series circuit switch valve and the series exhaust gas emission valve are both connected to the controller.

[0009] Furthermore, the parallel gas supply circuit is provided with a plurality of gas parallel circuit switch valves and a plurality of parallel exhaust gas emission valves; the gas parallel circuit switch valves are arranged between the gas supply module and the plurality of fuel cell stacks and between every two adjacent fuel cell stacks, and the parallel exhaust gas emission valves are arranged between each fuel cell stack and the atmosphere, and each gas parallel circuit switch valve and each parallel exhaust gas emission valve are connected to the controller.

[0010] Furthermore, an electrical series circuit switch is provided on the electrical series circuit; one end of the electrical series circuit switch is connected to the DC / DC converter, the other end of the electrical series circuit switch is connected to the multiple fuel cell stacks, and the electrical series circuit switch is also connected to the controller.

[0011] Furthermore, a plurality of electrical parallel circuit switches are provided on the electrical parallel circuit; one end of each electrical parallel circuit switch is connected to a fuel cell stack, the other end of each electrical parallel circuit switch is connected to the DC / DC converter, and each electrical parallel circuit switch is also connected to the controller.

[0012] Furthermore, the fuel cell series-parallel multi-stack cooperative operation system also includes a power module, and the power module is connected to the DC / DC converter, and the power module is also connected to the controller.

[0013] In a second aspect, an embodiment of the present invention further provides a control method for a fuel cell series-parallel multi-stack coordinated operation system, the method being applied to the fuel cell series-parallel multi-stack coordinated operation system described in the first aspect, the method comprising:

[0014] Get the load demand power;

[0015] Matching the load demand power with at least one preset output power interval to obtain a target output power interval to which the load demand power belongs;

[0016] A target operating mode corresponding to the target output power interval is obtained, and multiple fuel cell stacks are controlled to generate energy according to the target operating mode; wherein the target operating mode is a parallel operating mode or a series operating mode.

[0017] An embodiment of the present invention provides a fuel cell series-parallel multi-stack coordinated operation system and a control method thereof, the system comprising a plurality of fuel cell stacks, a gas supply module, a DC / DC converter, a series gas supply circuit, a parallel gas supply circuit, an electrical series circuit, an electrical parallel circuit and a controller. The series gas supply circuit and the electrical series circuit operate in a series operation mode selected by the controller; the parallel gas supply circuit and the electrical parallel circuit operate in a parallel operation mode selected by the controller. The present invention can fully combine the advantages of series operation and parallel operation of a fuel cell multi-stack system, improve the service life of the fuel cell, and reduce the complexity of the control strategy. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying any creative work.

[0019] Figure 1 A schematic block diagram of a fuel cell series-parallel multi-stack coordinated operation system provided by an embodiment of the present invention;

[0020] Figure 2 A flow chart of a control method for a fuel cell series-parallel multi-stack coordinated operation system provided by an embodiment of the present invention;

[0021] Figure 3 A schematic diagram of a first sub-process of a control method for a fuel cell series-parallel multi-stack coordinated operation system provided by an embodiment of the present invention;

[0022] Figure 4 A schematic diagram of a second sub-flow chart of a control method for a fuel cell series-parallel multi-stack coordinated operation system provided by an embodiment of the present invention;

[0023] Figure 5 A schematic diagram of the third sub-process of the control method of the fuel cell series-parallel multi-stack cooperative operation system provided by an embodiment of the present invention.

[0024] Wherein, the accompanying drawings are described as follows:

[0025] GS1, gas series circuit switch valve; SValve1, series exhaust valve; ES1, electrical series circuit switch;

[0026] GP1, GP2…GPn: Gas parallel circuit switch valve, 1…n represents the serial number;

[0027] PValve1, PValve2…PValven: parallel exhaust valves, 1…n represents the serial number;

[0028] EP1, EP2…EPn: electrical parallel circuit switches, 1…n represents the serial number. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] It should be understood that when used in this specification and the appended claims, the terms "include" and "comprises" indicate the presence of described features, integers, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0031] It should also be understood that the terms used in this specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the specification of the present invention and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an" and "the" are intended to include plural forms.

[0032] It should be further understood that the term "and / or" used in the present description and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0033] See also Figure 1 , Figure 1 A schematic block diagram of a system for coordinated operation of multiple stacks of fuel cells connected in series and in parallel is provided in an embodiment of the present invention, wherein the gas connection architecture and electrical connection architecture of the system for coordinated operation of multiple stacks of fuel cells connected in series and in parallel are shown.

[0034] The embodiment of the present invention provides a fuel cell series-parallel multi-stack coordinated operation system, comprising: a plurality of fuel cell stacks (such as Figure 1The fuel cell stack 1, fuel cell stack 2...fuel cell stack n, 1...n represents serial numbers), a gas supply module, a DC / DC converter, a series gas supply circuit, a parallel gas supply circuit, an electrical series circuit, an electrical parallel circuit and a controller (not shown in the figure); the gas supply module connects the multiple fuel cell stacks in series through the series gas supply circuit; the gas supply module also connects the multiple fuel cell stacks in series through the parallel gas supply circuit; the multiple fuel cell stacks are connected in series with the DC / DC converter through the electrical series circuit; the multiple fuel cell stacks are connected in parallel with the DC / DC converter through the electrical parallel circuit; the series gas supply circuit, the parallel gas supply circuit, the electrical series circuit and the electrical parallel circuit are all connected to the controller.

[0035] The series gas supply circuit and the electrical series circuit operate in a series working mode selected by the controller; the parallel gas supply circuit and the electrical parallel circuit operate in a parallel working mode selected by the controller.

[0036] In this embodiment, see Figure 1 The fuel cell series-parallel multi-stack cooperative operation system provided by the embodiment of the present invention is composed of multiple fuel cell stacks, a gas supply module, a DC / DC converter, a series gas supply circuit, a parallel gas supply circuit, an electrical series circuit, an electrical parallel circuit and a controller, wherein the gas supply module is used to provide the required reaction gas to the fuel cell stack, and the fuel cell stack can provide energy to the outside after inputting the reaction gas, and the DC / DC converter is used to convert the energy output by the fuel cell stack (at a certain voltage) into the energy required by the customer (at another voltage). The load is connected to the DC / DC converter, and the controller controls the fuel cell series-parallel multi-stack cooperative operation system to enter the parallel working mode or the series working mode according to the load demand power of the load, thereby providing the required energy to the load. When the load demand power is small, the fuel cell series-parallel multi-stack cooperative operation system enters the parallel working mode, avoiding the adverse effect of the multi-stack series system on the service life of the fuel cell when working at a high potential, and can improve the service life of the fuel cell. When the load demand power is large, the fuel cell series-parallel multi-stack cooperative operation system enters the series working mode, which can reduce the complexity of the control strategy and reduce the system cost.

[0037] In a more specific embodiment, the series gas supply circuit is used to transmit the reaction gas provided by the gas supply module to all fuel cell stacks and to discharge the exhaust gas generated by all fuel cell stacks into the atmosphere when the controller selects the series working mode; the parallel gas supply circuit is used to transmit the reaction gas provided by the gas supply module to a preset number of fuel cell stacks and to discharge the exhaust gas generated by the preset number of fuel cell stacks into the atmosphere when the controller selects the parallel working mode; the electrical series circuit is used to transmit the energy generated by all fuel cell stacks in series to the DC / DC converter when the controller selects the series working mode; the electrical parallel circuit is used to transmit the energy generated by the preset number of fuel cell stacks in parallel to the DC / DC converter when the controller selects the parallel working mode.

[0038] In this embodiment, see Figure 1 When the load demand power is relatively small, the fuel cell series-parallel multi-stack cooperative operation system enters the parallel working mode, opens the parallel gas supply circuit and closes the electrical parallel circuit, and closes the series gas supply circuit and opens the electrical series circuit. The reaction gas provided by the gas supply module is transmitted to a preset number of fuel cell stacks through the parallel gas supply circuit, and the exhaust gas generated by the preset number of fuel cell stacks is discharged into the atmosphere, and the energy generated by the preset number of fuel cell stacks is transmitted in parallel to the DC / DC converter through the electrical parallel circuit. It is not necessary for all fuel cell stacks in the entire system to be turned on at the same time, which avoids the adverse effect of the multi-stack series system on the service life of the fuel cell when working at a high potential, and can improve the service life of the fuel cell. When the load demand power is large, the fuel cell series-parallel multi-stack cooperative operation system enters the series working mode, opens the series gas supply circuit and closes the electrical series circuit, and closes the parallel gas supply circuit and opens the electrical parallel circuit. The reaction gas provided by the gas supply module is transmitted to all fuel cell stacks through the series gas supply circuit, and the exhaust gas generated by all fuel cell stacks is discharged into the atmosphere. The energy generated by all fuel cell stacks is transmitted in series to the DC / DC converter through the electrical series circuit, which can reduce the complexity of the control strategy and reduce the system cost.

[0039] Specifically, the output power of a single fuel cell stack when the average operating voltage is the preset voltage is PS1, then PSn is the output power of n fuel cell stacks when the average operating voltage is the preset voltage, n is the total number of multiple fuel cell stacks in the fuel cell series-parallel multi-stack cooperative operation system, preferably, the preset voltage is 0.8V, and the load demand power is P1. When P1≤PS1, the system enters the parallel operation mode, and energy is provided by a single fuel cell stack, that is, the reaction gas provided by the gas supply module is transmitted to the fuel cell stack 1 through the parallel gas supply circuit, and the exhaust gas generated by the fuel cell stack 1 is discharged to the atmosphere, and the energy generated by the fuel cell stack 1 is transmitted to the DC / DC converter through the electrical parallel circuit. When PS1<P1<PSn, the system still enters the parallel operation mode, and the quotient obtained by dividing P1 by PS1 is rounded down to a, which means that a fuel cell stacks (i.e., fuel cell stack 1 to fuel cell stack a) need to be put into operation at this time, and the reaction gas provided by the gas supply module is transmitted to the fuel cell stack 1 to the fuel cell stack a through the parallel gas supply circuit, and the exhaust gas generated by the fuel cell stack 1 to the fuel cell stack a is discharged to the atmosphere through the parallel gas supply circuit, and the energy generated by the fuel cell stack 1 to the fuel cell stack a is transmitted in parallel to the DC / DC converter through the electrical parallel circuit. When P1≥PSn, the system enters the series operation mode, and the reaction gas provided by the gas supply module is transmitted to all fuel cell stacks (i.e., fuel cell stack 1 to fuel cell stack n) through the series gas supply circuit, and the exhaust gas generated by all fuel cell stacks is discharged to the atmosphere, and the energy generated by all fuel cell stacks is transmitted in series to the DC / DC converter through the electrical series circuit.

[0040] In a more specific embodiment, a gas series circuit switch valve GS1 and a series exhaust gas emission valve SValve1 are provided on the series gas supply circuit; the gas series circuit switch valve GS1 is provided between the gas supply module and the multiple fuel cell stacks, and the series exhaust gas emission valve SValve1 is provided between the multiple fuel cell stacks and the atmosphere, and the gas series circuit switch valve GS1 and the series exhaust gas emission valve SValve1 are both connected to the controller.

[0041] In this embodiment, see Figure 1The series gas supply circuit is provided with a gas series circuit switch valve GS1 and a series exhaust gas emission valve SValve1. Specifically, one end of the gas series circuit switch valve GS1 is connected to the gas supply module, and the other end of the gas series circuit switch valve GS1 is connected to the first fuel cell stack 1. Every two adjacent fuel cell stacks are directly connected through a gas supply pipeline, and the last fuel cell stack n is connected to the atmosphere through the series exhaust gas emission valve SValve1. When the fuel cell series-parallel multi-stack cooperative operation system enters the series working mode, the controller controls the gas series circuit switch valve GS1 to open, and controls the series exhaust gas emission valve SValve1 to perform exhaust gas emission according to the preset exhaust control strategy. The reaction gas flows out of the gas supply module through the gas series circuit switch valve GS1-fuel cell stack 1-fuel cell stack 2...fuel cell stack n, and finally the gas is discharged into the atmosphere through the series exhaust gas emission valve SValve1.

[0042] In a more specific embodiment, the parallel gas supply circuit is provided with a plurality of gas parallel circuit switch valves (such as Figure 1 GP1, GP2...GPn, 1...n represents a serial number) and multiple parallel exhaust valves (such as Figure 1 PValve1, PValve2…PValven shown in the figure, 1…n represents serial numbers); the gas parallel circuit switch valve is arranged between the gas supply module and the multiple fuel cell stacks and between every two adjacent fuel cell stacks, the parallel exhaust gas emission valve is arranged between each fuel cell stack and the atmosphere, and each gas parallel circuit switch valve and each parallel exhaust gas emission valve are connected to the controller.

[0043] In this embodiment, see Figure 1, a plurality of gas parallel circuit switch valves and a plurality of parallel exhaust gas emission valves are arranged on the parallel gas supply circuit, and the number of gas parallel circuit switch valves and parallel exhaust gas emission valves is the same as the total number of multiple fuel cell stacks in the fuel cell series-parallel multi-stack cooperative operation system, that is, when there are n fuel cell stacks, n gas parallel circuit switch valves and n parallel exhaust gas emission valves are arranged on the parallel gas supply circuit. Specifically, one end of the gas parallel circuit switch valve GP1 is connected to the gas supply module, and the other end of the gas parallel circuit switch valve GP1 is connected to the fuel cell stack 1, that is, the gas parallel circuit switch valve GP1 is arranged between the gas supply module and the fuel cell stack 1. The gas parallel circuit switch valve GP2 is arranged between the fuel cell stack 1 and the fuel cell stack 2, and so on, the gas parallel circuit switch valve GPn is arranged between the fuel cell stack n-1 and the fuel cell stack n, that is, a gas parallel circuit switch valve is arranged between every two adjacent fuel cell stacks. Among them, when the fuel cell series-parallel multi-stack cooperative operation system enters the parallel working mode, the controller controls the preset number of gas parallel loop switch valves to open, thereby controlling the preset number of fuel cell stacks to provide energy in parallel, and controls the parallel exhaust gas emission valve connected to the last fuel cell stack in the preset number of fuel cell stacks to perform exhaust gas emission according to the preset exhaust control strategy. For example, when two fuel cell stacks are required to provide energy in parallel, the controller controls the gas parallel loop switch valve GP1 and the gas parallel loop switch valve GP2 to open, and controls the parallel exhaust gas emission valve PValve2 to perform exhaust gas emission according to the preset exhaust control strategy, and the reaction gas flows out of the gas supply module through the gas parallel loop switch valve GP1-fuel cell stack 1-gas parallel loop switch valve GP2-fuel cell stack 2, and finally the gas is discharged into the atmosphere through the parallel exhaust gas emission valve PValve2.

[0044] In a more specific embodiment, an electrical series circuit switch ES1 is provided on the electrical series circuit; one end of the electrical series circuit switch ES1 is connected to the DC / DC converter, the other end of the electrical series circuit switch ES1 is connected to the multiple fuel cell stacks, and the electrical series circuit switch ES1 is also connected to the controller.

[0045] In this embodiment, see Figure 1, an electrical series circuit switch ES1 is provided on the electrical series circuit, specifically, one end of the electrical series circuit switch ES1 is connected to one end of the DC / DC converter, and the other end of the electrical series circuit switch ES1 is connected to the first fuel cell stack 1, and every two adjacent fuel cell stacks are directly electrically connected, and the last fuel cell stack n is connected to the other end of the DC / DC converter, so that n fuel cell stacks are connected in series with the DC / DC converter through the electrical series circuit. Among them, when the fuel cell series-parallel multi-stack cooperative operation system enters the series working mode, the controller controls the electrical series circuit switch ES1 to close, so that the n fuel cell stacks are connected in series to provide energy.

[0046] In a more specific embodiment, the electrical parallel circuit is provided with a plurality of electrical parallel circuit switches (such as Figure 1 EP1, EP2...EPn shown in the figure, 1...n represents a serial number); one end of each electrical parallel circuit switch is connected to a fuel cell stack, the other end of each electrical parallel circuit switch is connected to the DC / DC converter, and each electrical parallel circuit switch is also connected to the controller.

[0047] In this embodiment, see Figure 1 , a plurality of electrical parallel circuit switches are arranged on the electrical parallel circuit, and the number of the electrical parallel circuit switches is the same as the total number of the plurality of fuel cell stacks in the fuel cell series-parallel multi-stack cooperative operation system, that is, when there are n fuel cell stacks, n electrical parallel circuit switches are arranged on the electrical parallel circuit. Specifically, one end of the fuel cell stack 1 is connected to one end of the DC / DC converter, and the other end of the fuel cell stack 1 is connected to the other end of the DC / DC converter through the electrical parallel circuit switch EP1; one end of the fuel cell stack 2 is connected to one end of the DC / DC converter, and the other end of the fuel cell stack 2 is connected to the other end of the DC / DC converter through the electrical parallel circuit switch EP2, and so on, one end of the fuel cell stack n is connected to one end of the DC / DC converter, and the other end of the fuel cell stack n is connected to the other end of the DC / DC converter through the electrical parallel circuit switch EPn, that is, each fuel cell stack is connected in parallel with the DC / DC converter through an electrical parallel circuit switch. Among them, when the fuel cell series-parallel multi-stack cooperative operation system enters the parallel working mode, the controller controls the preset number of electrical parallel circuit switches to be closed, thereby controlling the preset number of fuel cell stacks to provide energy in parallel. For example, when two fuel cell stacks are required to provide energy in parallel, the controller controls the electrical parallel circuit switch EP1 and the electrical parallel circuit switch EP2 to be closed, and fuel cell stack 1 and fuel cell stack 2 provide energy in parallel.

[0048] In a more specific embodiment, the fuel cell series-parallel multi-stack cooperative operation system also includes a power module (not shown in the figure), which is connected to the DC / DC converter and is also connected to the controller.

[0049] In this embodiment, the fuel cell series-parallel multi-stack cooperative operation system also includes a power module. When the load demand power P1 is less than the output power PS1 of a single fuel cell stack when the average operating voltage is a preset voltage, preferably, the preset voltage is 0.8V, the power module is used to receive the excess power of the system, wherein the power module can be a lithium battery. The reason why the power module is charged to increase the output power of the fuel cell stack until its output power is greater than PS1 is that the operation of the system at a power lower than PS1 is not conducive to the service life of the fuel cell stack.

[0050] The fuel cell series-parallel multi-stack cooperative operation system provided by the embodiment of the present invention includes multiple fuel cell stacks, a gas supply module, a DC / DC converter, a series gas supply circuit, a parallel gas supply circuit, an electrical series circuit, an electrical parallel circuit and a controller. Among them, the series gas supply circuit and the electrical series circuit operate in the series working mode selected by the controller; the parallel gas supply circuit and the electrical parallel circuit operate in the parallel working mode selected by the controller. The present invention can fully combine the advantages of the series operation and parallel operation of the fuel cell multi-stack system, improve the service life of the fuel cell, and reduce the complexity of the control strategy.

[0051] like Figure 2 As shown, Figure 2 A flow chart of a control method for a fuel cell series-parallel multi-stack coordinated operation system provided in an embodiment of the present invention. The control method for a fuel cell series-parallel multi-stack coordinated operation system provided in an embodiment of the present invention is applied to any embodiment of the aforementioned fuel cell series-parallel multi-stack coordinated operation system, and the method comprises steps S11 to S13.

[0052] S11. Obtain load demand power.

[0053] In this embodiment, the load is connected to the DC / DC converter, and the controller obtains the load demand power of the load. The controller controls the fuel cell series-parallel multi-stack cooperative operation system to provide the required energy to the load according to the obtained load demand power to meet the load requirements.

[0054] S12: Match the load demand power with at least one preset output power interval to obtain a target output power interval to which the load demand power belongs.

[0055] In this embodiment, the controller matches the load demand power with at least one preset output power interval to obtain the target output power interval to which the load demand power belongs, thereby determining how many fuel cell stacks are needed to be put into operation to meet the load requirements, and then controlling the fuel cell series-parallel multi-stack cooperative operation system to enter different target operating modes. Specifically, let the output power of a single fuel cell stack when the average operating voltage is the preset voltage be PS1, then PSn is the output power of n fuel cell stacks when the average operating voltage is the preset voltage, and n is the total number of multiple fuel cell stacks in the fuel cell series-parallel multi-stack cooperative operation system. Preferably, the preset voltage is 0.8V, and three preset output power intervals can be divided by PS1 and PSn, that is, the first preset output power interval is (0, PS1], the second preset output power interval is (PS1, PSn), and the third preset output power interval is [PSn, +∞).

[0056] S13, obtaining a target operating mode corresponding to the target output power interval, and controlling multiple fuel cell stacks to generate energy according to the target operating mode; wherein the target operating mode is a parallel operating mode or a series operating mode.

[0057] In this embodiment, different preset output power intervals correspond to different target working modes, and the load demand power is matched with at least one preset output power interval to obtain the target output power interval to which the load demand power belongs, and then the target working mode corresponding to the target output power interval is obtained, and multiple fuel cell stacks are controlled to generate energy according to the target working mode to meet the load requirements. Specifically, the target working mode is a parallel working mode or a series working mode. When the load demand power is small, the fuel cell series-parallel multi-stack cooperative operation system enters the parallel working mode, opens the parallel gas supply circuit and closes the electrical parallel circuit, and closes the series gas supply circuit and opens the electrical series circuit. The reaction gas provided by the gas supply module is transmitted to the preset number of fuel cell stacks through the parallel gas supply circuit, and the exhaust gas generated by the preset number of fuel cell stacks is discharged to the atmosphere, and the energy generated by the preset number of fuel cell stacks is transmitted in parallel to the DC / DC converter through the electrical parallel circuit. It is not necessary for all fuel cell stacks in the entire system to be turned on at the same time, which avoids the adverse effect of the multi-stack series system on the service life of the fuel cell when working at a high potential, and can improve the service life of the fuel cell. When the load demand power is large, the fuel cell series-parallel multi-stack cooperative operation system enters the series working mode, opens the series gas supply circuit and closes the electrical series circuit, and closes the parallel gas supply circuit and opens the electrical parallel circuit. The reaction gas provided by the gas supply module is transmitted to all fuel cell stacks through the series gas supply circuit, and the exhaust gas generated by all fuel cell stacks is discharged into the atmosphere. The energy generated by all fuel cell stacks is transmitted in series to the DC / DC converter through the electrical series circuit, which can reduce the complexity of the control strategy and reduce the system cost.

[0058] In one embodiment, if Figure 3 As shown, the parallel working mode includes a first parallel working mode, and step S13 includes:

[0059] S1311. If the target output power interval is a first preset output power interval, determining that the target operating mode is the first parallel operating mode in the parallel operating modes; wherein the first preset output power interval is (0, PS1], where PS1 is the output power of a single fuel cell stack when the average operating voltage is a preset voltage;

[0060] S1312. Control a single fuel cell stack to generate energy according to the first parallel operating mode; wherein, in the first parallel operating mode, the reaction gas provided by the gas supply module is transmitted to the single fuel cell stack through the parallel gas supply circuit, and the exhaust gas generated by the single fuel cell stack is discharged into the atmosphere, and the energy generated by the single fuel cell stack is transmitted to the DC / DC converter through the electrical parallel circuit.

[0061] In this embodiment, P1 is the load demand power, and PS1 is the output power of a single fuel cell stack when the average operating voltage is a preset voltage. Preferably, the preset voltage is 0.8V. When P1≤PS1, the target output power interval to which the load demand power P1 belongs is obtained as the first preset output power interval, wherein the first preset output power interval is (0, PS1], thereby obtaining the first parallel working mode, and controlling the fuel cell series-parallel multi-stack cooperative operation system to control the single fuel cell stack to generate energy according to the first parallel working mode. For details, refer to Figure 1 , the operations required for the fuel cell series-parallel multi-stack cooperative operation system to execute the first parallel working mode are: control the gas parallel circuit switch valve GP1 on the parallel gas supply circuit to open, control the electrical parallel circuit switch EP1 on the electrical parallel circuit to close, control the gas series circuit switch valve GS1 on the series gas supply circuit to close, and control the electrical series circuit switch ES1 on the electrical series circuit to open, and control the parallel exhaust gas emission valve PValve1 on the parallel gas supply circuit to perform exhaust gas emission according to the preset exhaust control strategy. Therefore, when controlling a single fuel cell stack to generate energy, the reaction gas flows through the gas parallel circuit switch valve GP1-fuel cell stack 1 after flowing out of the gas supply module, and finally the gas is discharged into the atmosphere through the parallel exhaust gas emission valve PValve1, and the energy generated by the fuel cell stack 1 is transmitted to the DC / DC converter through the electrical parallel circuit switch EP1 on the electrical parallel circuit. In another embodiment, when P1<PS1, since the load demand power P1 is less than the output power PS1 of the fuel cell stack when the average operating voltage is the preset voltage, a power module can be used to receive the excess power of the system, wherein the power module can be a lithium battery. The reason why the power module is charged to increase the output power of the fuel cell stack until its output power is greater than PS1 is because the operation of the system at a power lower than PS1 is not conducive to the service life of the fuel cell stack.

[0062] In one embodiment, if Figure 4 As shown, the parallel working mode also includes a second parallel working mode, and step S13 further includes:

[0063] S1321. If the target output power interval is the second preset output power interval, the target operating mode is determined to be the second parallel operating mode in the parallel operating mode; wherein the second preset output power interval is (PS1, PSn), PSn is the output power of n fuel cell stacks when the average operating voltage is the preset voltage, and n is the total number of multiple fuel cell stacks in the fuel cell series-parallel multi-stack cooperative operation system;

[0064] S1322. Control a preset number of fuel cell stacks to generate energy according to the second parallel operating mode; wherein, in the second preset parallel operating mode, the reaction gas provided by the gas supply module is transmitted to the preset number of fuel cell stacks through the parallel gas supply circuit, and the exhaust gas generated by the preset number of fuel cell stacks is discharged into the atmosphere, and the energy generated by the preset number of fuel cell stacks is transmitted in parallel to the DC / DC converter through the electrical parallel circuit.

[0065] In the present embodiment, PSn is the output power of n fuel cell stacks when the average operating voltage is a preset voltage, and n is the total number of multiple fuel cell stacks in the fuel cell series-parallel multi-stack cooperative operation system. Preferably, the preset voltage is 0.8V. When PS1<P1<PSn, the target output power interval to which the load demand power P1 belongs is obtained as the second preset output power interval, wherein the second preset output power interval is (PS1, PSn), thereby obtaining the second parallel working mode, and controlling the fuel cell series-parallel multi-stack cooperative operation system to control the preset number of fuel cell stacks to generate energy according to the second parallel working mode. Moreover, when PS1<P1<PSn, the quotient obtained by dividing P1 by PS1 is rounded down to a, indicating that a fuel cell stacks (i.e., fuel cell stack 1 to fuel cell stack a) are required to be put into operation at this time, that is, the preset number is a, and the fuel cell series-parallel multi-stack cooperative operation system controls a fuel cell stacks to generate energy according to the second parallel working mode. For details, refer to Figure 1The operations required for the fuel cell series-parallel multi-stack cooperative operation system to execute the second parallel working mode are: control the gas parallel circuit switch valves GP1 to GPa on the parallel gas supply circuit to be opened, and the remaining gas parallel circuit switch valves on the parallel gas supply circuit to be closed; control the electrical parallel circuit switches EP1 to EPa on the electrical parallel circuit to be closed; control the gas series circuit switch valve GS1 on the series gas supply circuit to be closed, and control the electrical series circuit switch ES1 on the electrical series circuit to be opened; and control the parallel exhaust emission valve PVAlvea connected to the last fuel cell stack in a fuel cell stack to perform exhaust emissions according to the preset exhaust control strategy. Thus, when controlling a fuel cell stack to generate energy, the reaction gas flows through the gas supply module through the gas parallel circuit switch valve GP1-fuel cell stack 1...gas parallel circuit switch valve GPa-fuel cell stack a, and finally the gas is discharged into the atmosphere through the parallel exhaust valve PValvea, and the energy generated by fuel cell stack 1 to fuel cell stack a is transmitted in parallel to the DC / DC converter through the electrical parallel circuit switches EP1 to EPa on the electrical parallel circuit. When the load demand power is small, it is not necessary for all fuel cell stacks in the entire system to be turned on at the same time, avoiding the adverse effects of the multi-stack series system on the service life of the fuel cell when working at a high potential, and can improve the service life of the fuel cell.

[0066] In one embodiment, if Figure 5 As shown, step S13 also includes:

[0067] S1331. If the target output power interval is a third preset output power interval, determine that the target working mode is the series working mode; wherein the third preset output power interval is [PSn, +∞);

[0068] S1332. Control all fuel cell stacks to generate energy according to the series working mode; wherein, in the series working mode, the reaction gas provided by the gas supply module is transmitted to all fuel cell stacks through the series gas supply circuit, and the exhaust gas generated by all fuel cell stacks is discharged into the atmosphere, and the energy generated by all fuel cell stacks is transmitted in series to the DC / DC converter through the electrical parallel circuit.

[0069] In this embodiment, when P1≥PSn, the target output power interval to which the load demand power P1 belongs is obtained as the third preset output power interval, wherein the third preset output power interval is [PSn, +∞), thereby obtaining the series working mode, and controlling the fuel cell series-parallel multi-stack cooperative operation system to control all fuel cell stacks to generate energy according to the series working mode, that is, at this time, all fuel cell stacks (i.e., fuel cell stack 1 to fuel cell stack n) need to be put into operation. For details, refer to Figure 1 , the operations required for the fuel cell series-parallel multi-stack coordinated operation system to execute the series operation mode are: control the gas parallel circuit switch valves GP1 to GPn on the parallel gas supply circuit to be closed, control the electrical parallel circuit switches EP1 to EPn on the electrical parallel circuit to be opened, control the gas series circuit switch valve GS1 on the series gas supply circuit to be opened, and control the electrical series circuit switch ES1 on the electrical series circuit to be closed, and control the series exhaust gas emission valve SValve1 on the series gas supply circuit to perform exhaust gas emission according to the preset exhaust control strategy. Therefore, when the fuel cell series-parallel multi-stack coordinated operation system is controlled to control all fuel cell stacks to generate energy in the series operation mode, the flow path of the reaction gas after flowing out of the gas supply module is gas series circuit switch valve GS1-fuel cell stack 1-fuel cell stack 2...fuel cell stack n, and finally the gas is discharged into the atmosphere through the series exhaust gas emission valve SValve1, and the energy generated by fuel cell stack 1 to fuel cell stack n is transmitted to the DC / DC converter in series through the electrical series circuit. When the load demand power is large, the fuel cell series-parallel multi-stack cooperative operation system enters the series working mode to control the output of each fuel cell stack. The control strategy is simple, and the working range and working time of each stack are consistent, which reduces the inconsistency of stack performance degradation, can reduce the complexity of the control strategy, and reduce system costs.

[0070] The control method of the fuel cell series-parallel multi-stack cooperative operation system provided in an embodiment of the present invention is applied to any embodiment of the aforementioned fuel cell series-parallel multi-stack cooperative operation system, including: obtaining load demand power; matching the load demand power with at least one preset output power interval to obtain the target output power interval to which the load demand power belongs; obtaining the target operating mode corresponding to the target output power interval, and controlling multiple fuel cell stacks to generate energy according to the target operating mode; wherein the target operating mode is a parallel operating mode or a series operating mode. The present invention controls the fuel cell series-parallel multi-stack cooperative operation system to enter the parallel operating mode when the load demand power is small, thereby avoiding the adverse effect of the multi-stack series system on the service life of the fuel cell when working at a high potential, and can improve the service life of the fuel cell. By controlling the fuel cell series-parallel multi-stack cooperative operation system to enter the series operating mode when the load demand power is large, the complexity of the control strategy can be reduced and the system cost can be reduced.

[0071] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. A fuel cell series-parallel multi-stack coordinated operation system, characterized in that: include: A plurality of fuel cell stacks, a gas supply module, a DC / DC converter, a series gas supply circuit, a parallel gas supply circuit, an electrical series circuit, an electrical parallel circuit and a controller; The gas supply module connects the multiple fuel cell stacks in series through the series gas supply circuit; the gas supply module also connects the multiple fuel cell stacks in series through the parallel gas supply circuit; the multiple fuel cell stacks are connected in series with the DC / DC converter through the electrical series circuit; the multiple fuel cell stacks are connected in parallel with the DC / DC converter through the electrical parallel circuit; the series gas supply circuit, the parallel gas supply circuit, the electrical series circuit and the electrical parallel circuit are all connected to the controller; The series gas supply circuit and the electrical series circuit operate in the series working mode selected by the controller; the parallel gas supply circuit and the electrical parallel circuit operate in the parallel working mode selected by the controller; the controller selects the working mode according to the load demand power, the output power of a single fuel cell stack when the average working voltage is a preset voltage, and the output power of the multiple fuel cell stacks when the average working voltage is the preset voltage; The series gas supply circuit is used to sequentially transmit the reaction gas provided by the gas supply module to all fuel cell stacks and discharge the tail gas generated by all fuel cell stacks to the atmosphere in the series operation mode selected by the controller; The parallel gas supply circuit is used to sequentially transmit the reaction gas provided by the gas supply module to a preset number of fuel cell stacks when the controller selects the parallel working mode, and to discharge the exhaust gas generated by the preset number of fuel cell stacks into the atmosphere.

2. The fuel cell series-parallel multi-stack coordinated operation system according to claim 1 is characterized in that: The electrical series circuit is used to transmit the energy generated by all fuel cell stacks in series to the DC / DC converter when the controller selects the series operation mode; The electrical parallel circuit is used to transmit the energy generated by the preset number of fuel cell stacks in parallel to the DC / DC converter when the controller selects the parallel working mode.

3. The fuel cell series-parallel multi-stack coordinated operation system according to claim 2 is characterized in that: The series gas supply circuit is provided with a gas series circuit switch valve and a series exhaust gas emission valve; the gas series circuit switch valve is arranged between the gas supply module and the multiple fuel cell stacks, and the series exhaust gas emission valve is arranged between the multiple fuel cell stacks and the atmosphere, and the gas series circuit switch valve and the series exhaust gas emission valve are both connected to the controller.

4. The fuel cell series-parallel multi-stack coordinated operation system according to claim 2, characterized in that: The parallel gas supply circuit is provided with a plurality of gas parallel circuit switch valves and a plurality of parallel exhaust gas emission valves; the gas parallel circuit switch valves are arranged between the gas supply module and the plurality of fuel cell stacks and between every two adjacent fuel cell stacks, and the parallel exhaust gas emission valves are arranged between each fuel cell stack and the atmosphere, and each gas parallel circuit switch valve and each parallel exhaust gas emission valve are connected to the controller.

5. The fuel cell series-parallel multi-stack coordinated operation system according to claim 2, characterized in that: An electrical series circuit switch is provided on the electrical series circuit; one end of the electrical series circuit switch is connected to the DC / DC converter, the other end of the electrical series circuit switch is connected to the multiple fuel cell stacks, and the electrical series circuit switch is also connected to the controller.

6. The fuel cell series-parallel multi-stack coordinated operation system according to claim 2, characterized in that: The electrical parallel circuit is provided with a plurality of electrical parallel circuit switches; one end of each electrical parallel circuit switch is connected to a fuel cell stack, the other end of each electrical parallel circuit switch is connected to the DC / DC converter, and each electrical parallel circuit switch is also connected to the controller.

7. The fuel cell series-parallel multi-stack coordinated operation system according to claim 1, characterized in that: It also includes a power supply module, which is connected to the DC / DC converter and is also connected to the controller.

8. A control method for a fuel cell series-parallel multi-stack coordinated operation system, applied to a fuel cell series-parallel multi-stack coordinated operation system as claimed in any one of claims 1 to 7, characterized in that: The method comprises: Get the load demand power; Matching the load demand power with at least one preset output power interval to obtain a target output power interval to which the load demand power belongs; wherein the preset output power interval is determined based on the output power of a single fuel cell stack in the fuel cell series-parallel multi-stack cooperative operation system when the average operating voltage is a preset voltage and the output power of the multiple fuel cell stacks when the average operating voltage is the preset voltage; A target operating mode corresponding to the target output power interval is obtained, and multiple fuel cell stacks are controlled to generate energy according to the target operating mode; wherein the target operating mode is a parallel operating mode or a series operating mode.

9. The control method of a fuel cell series-parallel multi-stack coordinated operation system according to claim 8, characterized in that: The parallel operation mode includes a first parallel operation mode, and the acquiring of a target operation mode corresponding to the target output power interval and controlling a plurality of fuel cell stacks to generate energy according to the target operation mode includes: If the target output power interval is the first preset output power interval, the target operating mode is determined to be the first parallel operating mode in the parallel operating mode; wherein the first preset output power interval is (0, PS1], PS1 is the output power of a single fuel cell stack when the average operating voltage is a preset voltage; A single fuel cell stack is controlled to generate energy according to the first parallel operating mode; wherein, in the first parallel operating mode, the reaction gas provided by the gas supply module is transmitted to the single fuel cell stack through the parallel gas supply circuit, and the exhaust gas generated by the single fuel cell stack is discharged into the atmosphere, and the energy generated by the single fuel cell stack is transmitted to the DC / DC converter through the electrical parallel circuit.

10. The control method of a fuel cell series-parallel multi-stack coordinated operation system according to claim 9, characterized in that: The parallel operation mode also includes a second parallel operation mode, and the step of acquiring a target operation mode corresponding to the target output power interval and controlling a plurality of fuel cell stacks to generate energy according to the target operation mode also includes: If the target output power interval is the second preset output power interval, the target operating mode is determined to be the second parallel operating mode in the parallel operating mode; wherein the second preset output power interval is (PS1, PSn), PSn is the output power of n fuel cell stacks when the average operating voltage is the preset voltage, and n is the total number of multiple fuel cell stacks in the fuel cell series-parallel multi-stack cooperative operation system; A preset number of fuel cell stacks are controlled to generate energy according to the second parallel operating mode; wherein, in the second preset parallel operating mode, the reaction gas provided by the gas supply module is transmitted to the preset number of fuel cell stacks through the parallel gas supply circuit, and the exhaust gas generated by the preset number of fuel cell stacks is discharged into the atmosphere, and the energy generated by the preset number of fuel cell stacks is transmitted in parallel to the DC / DC converter through an electrical parallel circuit.

11. The control method of a fuel cell series-parallel multi-stack coordinated operation system according to claim 10, characterized in that: The step of acquiring a target operating mode corresponding to the target output power interval and controlling a plurality of fuel cell stacks to generate energy according to the target operating mode further includes: If the target output power interval is the third preset output power interval, the target working mode is determined to be the series working mode; wherein the third preset output power interval is [PSn, +∞); All fuel cell stacks are controlled to generate energy according to the series operation mode; wherein, in the series operation mode, the reaction gas provided by the gas supply module is transmitted to all fuel cell stacks through the series gas supply circuit and the exhaust gas generated by all fuel cell stacks is discharged into the atmosphere, and the energy generated by all fuel cell stacks is transmitted in series to the DC / DC converter through the electrical parallel circuit.

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