Fuel cell-based generation system and control method thereof

Abstract

A fuel cell-based generation system is provided. The fuel cell-based generation system includes a fuel cell subsystem comprising at least one fuel cell coupled to a power terminal which is configurable to connect with a load system; a battery subsystem comprising at least one battery coupled to the power terminal and configured to provide a state of charge (SoC) value of the at least one battery, the at least one battery being capable of discharging to the load system and charging from the at least one fuel cell; and a controller configured to operate the fuel cell-based generation system by coordinated control of the battery subsystem and the fuel cell subsystem, wherein the coordinated control is provided by dynamically adjusting a power setpoint of the at least one fuel cell based on the SoC value of the at least one battery.

Description

FUEL CELL-BASED GENERATION SYSTEM AND CONTROLMETHOD THEREOFTECHNICAL FILED

[0001] The present disclosure relates to a fuel cell-based generation system and a method for controlling the fuel cell-based generation system.BACKGROUND

[0002] A fuel cell is a chemical device that converts chemical energy into electrical energy. It mainly converts the Gibbs free energy part of the chemical energy into electrical energy through electrochemical reactions, which is not limited by the Carnot cycle effect and therefore has high efficiency. Taking the hydrogen-oxygen fuel cell as an example, its reaction principle is the reverse process of electrolyzing water. Hydrogen gas undergoes oxidation at the anode, producing hydrogen ions and electrons, and the electrons travel through the external circuit to reach the cathode. The hydrogen ions also reach the cathode through the proton exchange membrane and react with electrons and oxygen at the cathode to generate water.

[0003] Fuel cells have the advantage of high-power generation efficiency. Fuel cells can theoretically operate at near 100% thermal efficiency. In actual operation, the conversion efficiency is mostly within the range of 45% to 60%. If considering the use of heat dissipation, the overall efficiency can reach more than 80%. Fuel cells also have the advantage of low environmental pollution, with very few harmful gases emitted and the main product being water, making them environmentally friendly.

[0004] However, when a fuel cell-based system is used to power a load and the demand power of the load changes rapidly, the response speed of the fuel cell may not be fast enough. This is because the fuel cell generates electrical energythrough electrochemical reactions, which take time to complete. Moreover, the fuel cell-based system usually comprises multiple parts such as a fuel cell stack, a gas supply system (including air compressors), a thermal management system, and a control system. The collaborative work between these parts also takes time. Such a fuel cell-based system requires time to readjust the operation state of each part. If there is a rapid change in demand power but the response speed of the fuel cell-based system is not fast enough, this may lead to instability in output voltage and could cause other issues, such as power fluctuations or even system failure.SUMMARY

[0005] According to an embodiment of the present disclosure, a fuel cell-based generation system is provided. The fuel cell-based generation system includes a fuel cell subsystem comprising at least one fuel cell coupled to a power terminal which is configurable to connect with a load system; a battery subsystem comprising at least one battery coupled to the power terminal and configured to provide a state of charge (SoC) value of the at least one battery, the at least one battery being capable of discharging to the load system and charging from the at least one fuel cell; and a controller configured to operate the fuel cell-based generation system by coordinated control of the battery subsystem and the fuel cell subsystem, wherein the coordinated control is provided by dynamically adjusting a power setpoint of the at least one fuel cell based on the SoC value of the at least one battery.

[0006] According to another embodiment of the present disclosure, a method for controlling a fuel cell-based generation system is provided. The fuel cellbased system includes a fuel cell subsystem comprising at least one fuel cell coupled to a power terminal which is configurable to connect with a load system; and a battery subsystem comprising at least one battery coupled to the power terminal and configured to provide a state of charge (SoC) value of the at least one battery, the at least one battery being capable of discharging to the loadsystem and charging from the at least one fuel cell. The method includes operating the fuel cell-based generation system by coordinated control of the battery subsystem and the fuel cell subsystem. The coordinated control is provided by dynamically adjusting a power setpoint of the at least one fuel cell based on the SoC value of the at least one battery.BRIEF DESCRIPTION OF THE DRAWINGS

[0007] The disclosed aspects will hereinafter be described in connection with the appended drawings, which are provided to illustrate but not to limit the scope of the present disclosure.

[0008] Figure 1 is a block diagram illustrating a fuel cell-based generation system according to an embodiment of the present disclosure.

[0009] Figure 2 A is a block diagram illustrating an implementation of the controller of the fuel cell-based generation system shown in Figure 1.

[0010] Figure 2B illustrates multiple SoC ranges according to examples of the present disclosure.

[0011] Figure 3 is a block diagram illustrating a modified example of the fuel cell-based generation system shown in Figure 1.

[0012] Figure 4 is a block diagram illustrating another modified example of the fuel cell-based generation system shown in Figure 1.

[0013] Figure 5 is a flowchart diagram of a method for controlling a fuel cellbased generation system according to an embodiment of the present disclosure.

[0014] Figures 6A-6D show sub-steps of the main steps of the method illustrated in Figure 5.DETAILED DESCRIPTIONOverview

[0015] Examples of the present disclosure relate to a fuel cell-based generation system and a method for controlling the fuel cell-based generation system. The fuel cell-based generation system comprises a combination of a fuel cell (FC) and a battery (BAT), for example, a lithium battery, and is thus referred to as a FC- BAT generation system. In this system, the fuel cell serves as the main energy source, while the battery provides temporary backup power during fuel cell startup or when there are sudden changes in load power demand. This combination leverages not only the fuel cell's advantages of high efficiency and environmental protection but also the battery's high-power density and fast response characteristics, thereby enhancing the reliability and performance of the entire system.

[0016] The control method according to examples of the present disclosure involves determining and adjusting the power setpoint of the fuel cell, thereby enhancing overall performance of the system, extending the service life of both the fuel cell and battery, and ensuring stable and reliable power supply across various operating conditions through precise control of the fuel cell power setpoint.

[0017] For example, while ensuring that the load demand power is met, this control method considers the SOC value of the battery to avoid overcharging the battery (which may lead to battery damage or safety hazards) or deep discharge (which may affect battery life and performance) through the power setpoint of the fuel cell. Furthermore, it considers the operating efficiency and stability of the fuel cell, which is achieved by limiting the value of the power setpoint and change rate of the power setpoint of the fuel cell.Example systems

[0018] Figure 1 shows a fuel cell-based power generation system 100(hereinafter referred to as system 100) according to an embodiment of the present disclosure. The system 100 has a power terminal 101 and can be coupled to a load system 200 to supply power to the load system 200 through the power terminal 101. The load system 200 may include one or more DC loads, or one or more AC loads, or a combination of DC and AC loads. In other words, the system 100 can supply power to DC loads, or to AC loads, or to a hybrid of DC and AC loads.

[0019] With reference to Figure 1, the system 100 comprises a fuel cell subsystem 10, a battery subsystem 20, a controller 60, converters 30A and 40A, and a transformer 50. In an example, the system 100 may also include a housing (i.e., a container) where the fuel cell subsystem 10, battery subsystem 20, controller 60, converters 30A and 40A, and transformer 50 are housed. The power terminal 101, located on the housing, serves as an interface for the system 100 to output electric power.

[0020] The fuel cell subsystem 10 includes at least one fuel cell 11. The fuel cell subsystem 10 can also increase its power generation capacity by including more fuel cells. For example, the fuel cell subsystem 10 can also include an additional fuel cell unit 12, which includes one or more fuel cells. In addition, the fuel cell subsystem 10 can also include a fuel cell controller (not shown) for controlling the operation of the fuel cell subsystem 10 according to control instructions from a higher-level controller, such as the controller 60. The fuel cell subsystem 10 can also include sensors (not shown) to detect the operating status of fuel cells, such as temperature sensors and flow sensors. The fuel cell subsystem 10 can also include auxiliary equipment (not shown) for assisting the operation of the fuel cell subsystem 10, such as heat exchangers and water pumps.

[0021] The battery subsystem 20 includes at least one battery 21. The battery 21 is, for example, a lithium-ion battery. The battery subsystem 20 can operate in one of the following modes: 1) discharging to the load system 200; 2) being charged by the fuel cell subsystem 10; and 3) neither discharging nor beingcharged. The battery subsystem 20 can increase its discharge capacity or storage capacity by including more batteries. For example, the battery subsystem 20 can include an additional battery unit 22, which includes one or more batteries. In addition, the battery subsystem 20 can also include a battery management system (BMS) for monitoring, managing, and protecting the battery subsystem 20. For example, the BMS collects status parameters such as a voltage, current, state of charge and temperature of the battery subsystem 20 and calculates the maximum available charging power and the maximum available discharging power of the battery subsystem 20 under the current state (i.e., real time maximum charging power and real time maximum discharging power).

[0022] Due to a possible difference in output voltage levels between the fuel cell subsystem 10 and the battery subsystem 20, the DC-AC converter 30A coupled to the fuel cell subsystem 10 and the DC-AC converter 40A coupled to the battery subsystem 20 can be used to convert the output voltages of the fuel cell subsystem 10 and the battery subsystem 20 to the same voltage level, which is required by the load system 200. The DC-AC converter 30A is coupled to an input winding of the transformer 50, while the DC-AC converter 40A is coupled to another input winding of the transformer 50. The output winding of the transformer 50 is coupled to the load system 200 via the power terminal 101. The transformer 50 can play a role of electrical isolation.

[0023] In an example, one of the DC-AC converters, either 30A or 40 A, may be omitted. That is, the system 100 may be implemented to convert the voltage level output by either the fuel cell subsystem 10 or the battery subsystem 20 to a voltage level equal to the output voltage of the other, using only one DC-AC converter coupled to either the fuel cell subsystem 10 or the battery subsystem 20.

[0024] The controller 60 can communicate with the fuel cell subsystem 10 and the battery subsystem 20 to receive real time information from each. For example, the fuel cell controller of the fuel cell subsystem 10 provides information aboutthe real-time status of the fuel cell 11 to the controller 60. This information includes, for example, the maximum and minimum output power that the fuel cell 11 can currently provide (i.e., the maximum and minimum available output power of the fuel cell 11). Similarly, the BMS of the battery subsystem 20 provides information about the real-time status of the battery 21 to the controller 60. This information includes, for example, the real time SoC value, real time maximum charging power (i.e., maximum available charging power), and real time maximum discharging power (i.e., maximum available discharging power) of the battery 21. The controller 60 can also communicate with the load system 200 to receive real time information from the load system 200. This information includes, for example, the demand power of the load system 200 and changes in the demand power.

[0025] The controller 60 dynamically adjusts the power setpoint of the fuel cell subsystem 10, which represents the target output power of the fuel cell subsystem 10, based on information received from both the fuel cell subsystem 10 and the battery subsystem 20, as well as information received from the load system 200. Such coordinated control ensures that the demand power of the load system 200 is met while preventing deep discharging or overcharging of the batteries in the battery subsystem 20, enabling the overall system 100 to operate in a stable state.

[0026] The controller 60 can be implemented through hardware, software, or a combination of both, including code stored in a non-transitory computer-readable medium and executed as instructions by a processor. When it comes to hardware implementation, it may be embodied in an application-specific integrated circuit (ASIC), a digital signal processor (DSP), a digital signal processing device (DSPD), a programmable logic device (PLD), a field-programmable gate array (FPGA), a processor, a controller, a microcontroller, a microprocessor, an electronic unit, or any combination of these. As for software implementation, it may encompass microcode, program code, or code segments. The software can be stored in a machine-readable storage medium, such as a memory.

[0027] Next, the working principle of the system 100 will be explained using an example of how the controller 60 cooperatively controls the fuel cell 11 and the battery 21.

[0028] In the system 100, the fuel cell 11 serves as the primary energy source, while the battery 21 functions as a backup energy source. Specifically, during the start-up phase of the fuel cell 11, the battery 21 supplies electrical power to enable the electrical devices of the fuel cell 11 to activate and enter a working state. When the SoC value of the battery 21 falls within a predetermined range, indicating that it is neither overly charged nor depleted, the battery 21 remains idle, and the controller 60 sets the power setpoint of the fuel cell 11 (i.e., FC power setpoint) to match the demand power of the load system 200.

[0029] During operation of the system 100, there may be a situation where the demand power of the load system 200 increases. In this case, due to the relatively slow power change of the fuel cell 11, the battery 21 will discharge to the load system 200 to quickly meet the increase in demand power of the load system 200. During the discharge process, there may be a situation where the SoC of battery 21 becomes lower than the lower limit of the predetermined SoC range. In this case, the controller 60 will increase the power setpoint of the fuel cell 11 , so that part of the power generated by the fuel cell 11 is used to charge battery 21, while the other part is used to provide power to the load system 200. After system 100 has operated for a period of time in this way, the SoC of the battery 21 will return to the predetermined SoC range.

[0030] During operation of the system 100, there may be a decrease in the power demand of the load system 200. In this case, due to the relatively slow power response of the fuel cell 11, the battery 21 will absorb the excess power generated by the fuel cell 11, meaning that the fuel cell 11 charges the battery 21 to accommodate the decrease in the power demand of the load system 200. During this process, there may be a situation where the SoC of the battery 21 exceeds the upper limit of the predetermined SoC range. In this case, thecontroller 60 will reduce the power setpoint of the fuel cell 11 and allow the battery 21 to discharge to the load system 200, such that part of the power demand of the load system 200 is provided by the fuel cell 11 and the other part is provided by the battery 21. After the system 100 operates for a period of time in this way, the SoC of the battery 21 will return to the predetermined SoC range.

[0031] It should be understood that, according to the control strategy of examples of the present disclosure, the most suitable coordinated control can be provided for various SoC change scenarios, so that the demand power of the load system 200 is met, and there is no deep discharge or overcharge of the battery 21 , thus allowing the system 100 to operate in a stable state. Examples of the coordinated control will be introduced below.

[0032] Figure 2A shows an exemplary implementation of the controller 60. As shown in Figure 2 A, the controller 60 includes multiple determination units, such as first to fourth determination units 61 -64, a multiplexer 65, and a setpoint limiter 66.

[0033] In this example, each module (i.e., each determination unit, the multiplexer or the setpoint limiter) of the controller 60 can be implemented through hardware, software, or a combination of both, including code stored in a non-transitory computer-readable medium and executed as instructions by a processor. When it comes to hardware implementation, it may be embodied in an application-specific integrated circuit (ASIC), a digital signal processor (DSP), a digital signal processing device (DSPD), a programmable logic device (PLD), a field-programmable gate array (FPGA), a processor, a controller, a microcontroller, a microprocessor, an electronic unit, or any combination of these. As for software implementation, it may encompass microcode, program code, or code segments. The software can be stored in a machine-readable storage medium, such as a memory.

[0034] Each of the multiple determination units 61-64 is used to determine the FC power setpoint in the case where the SoC value of the battery 21 is within oneof multiple SoC ranges. The multiplexer 65 includes multiple channels (e.g., first to fourth channels 651-654) corresponding to the multiple SoC ranges. Each channel has an input and an output. The input is connected to one of the multiple determination units 61-64 to receive the FC power setpoint determined by the determination unit. The output of each channel can be gated to transmit the FC power setpoint to the setpoint limiter 66. The setpoint limiter 66 employs a saturation limiter and a ramp limiter to constrain the FC power setpoint, ensuring safe, efficient, and stable operation of the fuel cell. Additionally, it safeguards the stability of the system 100 and any super system it is interconnected with. Subsequently, the setpoint limiter 66 transmits the FC power setpoint that meets each limit threshold to the fuel cell 11 as the target output power of the fuel cell 11.

[0035] In an example, the multiple SoC ranges include four SoC ranges. Below, each of the four SoC ranges is described with reference to Figure 2B.

[0036] With reference to Figure 2B, the first SoC range is the predetermined SoC range mentioned above, which has an upper limit value and a lower limit value. When the SoC value of the battery 21 is within this range, the power setpoint of the fuel cell 22 is determined by the first determination unit 61.

[0037] The second SoC range, also known as a low SoC range, is a range in which SoC values are less than the lower limit value. When the SoC value of the battery 21 is within this range, the power setpoint of the fuel cell 22 is determined by the second determination unit 62.

[0038] The third SoC range, also known as a first high SoC range, is a range in which SoC values are greater than the upper limit value but less than a critical value, which is higher than the upper limit value. When the SoC value of the battery 21 is within this range, the power setpoint of the fuel cell 22 is determined by the third determination unit 63.

[0039] The fourth SoC range, also known as a second high SoC range, is a range in which SoC values are greater than the critical value. The critical valueis a very high SoC value such that the battery 21 discharges to the load system 200 with large discharge power, thereby causing the output power of the fuel cell 11 to be lower than the minimum generation threshold of the fuel cell 11. When the output power of the fuel cell 11 is lower than the minimum generation threshold, the fuel cell 11 will turn off or enter a standby state. Thus, when the SoC value of the battery 21 is within this range, the fourth determination unit 64 determines the power setpoint of the fuel cell 11 to be zero, and the fuel cell 11 turns off or enters a standby state.

[0040] The system 100 in Figure 1 has various variations in topology, and some of these variations are described below.

[0041] Figure 3 shows a modified example of the system 100 in Figure 1.

[0042] The system 100’ in Figure 3 has most of the same features as the system 100 in Figure 1, except that the fuel cell subsystem 10 is coupled to a DC bus through a DC-DC converter 30B, the battery subsystem 20 is coupled to the DC bus through another DC-DC converter 40B, and these two DC-DC converters 30B and 40B are coupled to the transformer 50 through a DC- AC converter 70. In this configuration, the output voltage levels of both the fuel cell subsystem 10 and the battery subsystem 20 are first converted to the same voltage level by the DC-DC converters 30B and 40B, and then they are converted to a voltage level suitable for the load system 200 by the DC-AC converter 70.

[0043] Figure 4 shows another modified example of the system 100 in Figure 1.

[0044] The system 100 in Figure 1 and the system 100' in Figure 3 are both suitable for powering AC loads. Here, the system 100" in Figure 4 is suitable for powering DC loads. The system 100” in Figure 4 has most of the same features as the system 100 in Figure 1, except that the fuel cell subsystem 10 is coupled to a DC bus through a DC-DC converter 30B, the battery subsystem 20 is coupled to the DC bus through another DC-DC converter 40B, and the DC bus is directly coupled to the load system 200 via the power terminal 101. In this way, the outputvoltage levels of the fuel cell subsystem 10 and the battery subsystem 20 are converted to the same voltage level that is suitable for the load system 200 through the DC-DC converters 30B and 40B.

[0045] In some examples, in the case where the output voltage levels of the fuel cell subsystem 10 and the battery subsystem 20 are the same, the DC-DC converters or DC-AC converters coupled to them can be omitted.

[0046] In some examples, the fuel cell subsystem 10 and the battery subsystem 20 can be directly connected to the load system 200 a DC bus or an AC bus, omitting the transformer 50.

[0047] It is noted that, in various examples of the present disclosure, the fuel cell subsystem 10 can be coupled to the battery subsystem 20 and the power terminal 101 through a power electronics circuit that includes one or more converters and / or a transformer. That is to say, the converters and / or a transformer described above can be referred to as being part of the power electronics circuit.Example methods

[0048] Figure 5 shows a control method 500 for controlling a fuel cell-based power supply system according to an embodiment of the present disclosure. The method 500 can be executed by the controller 60. Below, the method 500 is introduced by way of an example, where the controller 60 coordinatively controls the fuel cell 11 and the battery 21.

[0049] With reference to Figure 5, at block 510, the controller 60 receives realtime information from the fuel cell subsystem 10 and the battery subsystem 20, as well as information from the load system 200.

[0050] The real-time information from the fuel cell subsystem 10 can include: temperatures, currents, voltages, and other state parameters of the fuel cell 11 , as well as the maximum and minimum output power that the fuel cell 11 cancurrently provide.

[0051] The real-time information from the battery subsystem 20 can include: the real-time SoC value of the battery 21, the maximum charging power, and the maximum discharging power that the battery 21 can currently provide (i.e., the maximum available charging power and the maximum available discharging power).

[0052] The information from the load system 200 can include a load profile. The load profile can be expressed as a curve showing the change in power demand over time. Based on the load profile, the following information can be obtained: 1) the amount of change in the demand power of the load system 200; 2) the frequency of change in the demand power; 3) the time period during which the demand power changes; and 4) the energy required for every load change over a given time period. Furthermore, based on the load profile, the controller 60 can predict the trend of change in the demand power over a time period in the future.

[0053] At block 520, the controller 60 detects the SoC value of the battery 21 and determines its relationship to the multiple SoC ranges. Specifically, it checks which one of the multiple SoC ranges includes the current SoC value. For example, the SoC value may be: within the predetermined range; less than the lower limit value of the predetermined range; greater than the upper limit value of the predetermined range but less than the critical value; or greater than the critical value.

[0054] If the detection result indicates that the SoC value of the battery 21 is within the predetermined SoC range, that is, the SoC value is lower than the upper limit and higher than the lower limit, the method 500 proceeds to block 530.

[0055] At block 530, the controller 60 operates the system 100 in a first operation mode. In this mode, the controller 60 adjusts the power setpoint of the fuel cell 11 to be equal to the demand power of the load system 200.

[0056] Next, examples of the upper and lower limit values of the predeterminedSoC range will be introduced.

[0057] The upper and lower limit values of the predetermined SoC range can be preconfigured in the controller 60. For example, the upper and lower limit values are predetermined according to the type of the battery 21 and stored in the controller 60, as different types of batteries have different SoC normal operating ranges. In other words, the predetermined SoC range may vary depending on the type of the battery 21. The controller 60 may also adjust the upper and lower limit values based on one or more of the following factors: 1) the state of health of the battery 21; 2) the ambient condition including a temperature, humidity, pressure of the battery 21; and 3) the load profile of the load system 200.

[0058] For example, the state of health of the battery 21 refers to the ability of the battery to store and release electrical energy during its life cycle. Over time, the battery 21 will gradually degrade due to factors such as charge and discharge cycles, self-discharge, temperature fluctuations, etc. The BMS of the battery 21 can assess its health status by monitoring parameters such as voltage, current, internal resistance, and capacity of the battery 21. When communication information from the BMS indicates a decline in the state of health of the battery 21, the controller 60 can reduce the upper and increase lower limit values to extend battery life and avoid safety risks.

[0059] For example, the performance and lifetime of the battery 21 are significantly influenced by the ambient temperature. Extremely high or low temperatures can not only decrease its performance and shorten its lifetime, but also pose a safety risk. To address this, the controller 60 continuously monitors the ambient temperature of the battery 21 through a temperature sensor (not shown). Depending on the temperature, the controller 60 adjusts the upper and lower limit values of the predetermined SoC range accordingly. In a high temperature environment, for instance, when the ambient temperature exceeds a predetermined high temperature threshold, the controller 60 automatically reduces both the upper and lower limit values by a certain percentage (e.g., 10%each) to protect the battery 21 from potential damage. Conversely, in a low temperature environment, where the ambient temperature falls below a low temperature threshold, the controller 60 increases both the upper and lower limit values by a certain percentage (e.g., 10% each) to ensure optimal battery performance.

[0060] For example, based on the load profile of the load system 200, the power demand of the load system 200 at different time points can be obtained. The power demand may vary due to various factors such as application scenarios, operation time during a day, and user-customized requirements. The controller 60 can predict future power demands by analyzing the load profile and adjust the upper and lower limit values accordingly. An example of the adjustment is when it is predicted that there will be a peak in demand power, the controller 60 increases the upper and lower limit values (for example, by 10% each); when it is predicted that there will be a low power demand, the controller 60 decreases the upper and lower limit values (for example, by 10% each).

[0061] In the first operation mode, the controller 60 may perform a battery balancing function (block 531) and a sensitivity limiting function (block 532). Below, these two functions are introduced in detail.

[0062] With reference to Figure 6 A, at block 531 , in the case that the SoC value of the battery 21 is within the predetermined SoC range, the controller 60 can perform the battery balancing function. The controller 60 detects a difference between the maximum charging power value and the maximum discharging power value that the battery 21 can currently provide based on the real-time information from the battery subsystem 20 and determines whether the power difference is greater than a power difference threshold. If it is determined that the power difference is greater than the power difference threshold, the controller 60 adjusts the power setpoint of the fuel cell 11 so that the available power of the battery 21 remains at a central value relative to the maximum charging power and the maximum discharging power. The power difference threshold can bepredetermined based on the type of the battery 21 and stored in the controller 60.

[0063] This function is particularly useful when the maximum available charging power and maximum available discharging power of the battery 21 lead to a large difference. For example, in low temperature environments, the maximum available charging power of the battery 21 may significantly decrease, but the demand for discharging power may still be high. In this case, this function can adjust the output of the fuel cell 11 by adjusting the power setpoint of the fuel cell 11 to balance this difference and ensure stable operation of the system 100.

[0064] In addition, this function can be selectively turned on or turned off. In an example, when the available charging power and discharging power of the battery 21 are much higher than the demand power of the load system 200, this function can be turned off. In another example, when it is known that the power demand of the load system 200 will not change for a long period of time, this function can be turned off during this period of time.

[0065] With continued reference to Figure 6A, at block 532, in the case that the SoC value of the battery 21 is within the predetermined SoC range, the controller 60 can perform a sensitivity limit function. This function can reduce the change frequency of the power setpoint by means of setting one or more sensitivity thresholds. For example, in the situation of a sudden change in the power demand for a short time, by applying this function, changing the power setpoint of the fuel cell 11 can be avoided.

[0066] In an example, the controller 60 determines whether the power demand of the load system 200 has changed by at least a sensitivity threshold over a predetermined time period, based on real-time information from the load system 200. If it is determined that the power demand of the load system 200 has changed by at least the sensitivity threshold over the predetermined time period, the controller 60 adjusts the power setpoint of the fuel cell 11 to match the new, changed power demand. That is, the new power setpoint equals the updated demand power.

[0067] In this example, both the sensitivity threshold and the predetermined time period are used as thresholds to limit the sensitivity of the change in the power setpoint of the fuel cell 11. The sensitivity threshold and the predetermined time period can be preset and stored in the controller 60 based on the stability- related test results of the system 100. In addition, both the sensitivity threshold and the predetermined time period are adjustable. For example, the controller 60 can adjust the sensitivity of the power setpoint change by configuring these values. That is, both the sensitivity threshold and the predetermined time can be set to react differently to changes in demand power, depending on whether the change is small or large, and whether it is short-term or long-term continuous.

[0068] It should be understood that the present disclosure does not limit the execution order of block 531 and block 532. That is, both blocks can be executed simultaneously or sequentially.

[0069] If the detection result is that the SoC value of the battery 21 is lower than the lower limit value of the predetermined SoC range, the method 500 proceeds to block 540.

[0070] At block 540, the controller 60 controls the system 100 in a second operation mode. In the second operation mode, the controller 60 determines the power setpoint of the fuel cell 11 to be higher than the demand power of the load system 200. Consequently, a part of the power generated by the fuel cell 11 is used to provide power to the load system 200, while another part is used to charge the battery 21. Below, an example of the block 540 is described (see blocks 541- 545).

[0071] With reference to Figure 6B, at block 541, the controller 60 determines charging margin parameters of the battery 21, which include the minimum load charging power and a corresponding minimum charging margin, as well as the maximum load charging power and a corresponding maximum charging margin.

[0072] In an example, the charging margin parameters are preconfigured based on the type of battery 21 and stored in the controller 60. This is because differenttypes of batteries have different charging and discharging characteristics and safety requirements, so different charging margin parameters need to be configured. Moreover, considering that relying solely on the charging margin parameters that have been configured based on the battery type may not be sufficient to cope with changing application scenarios, the controller 60 can adjust the preconfigured charging margin parameters based on at least one of the following factors: 1) the state of health of the battery 21; 2) the ambient condition including a temperature, humidity, pressure of the battery 21; and 3) the load profile of the load system 200.

[0073] For example, as the battery 21 is used and ages, its capacity and performance will gradually decrease. When the state of health of the battery 21 decreases, in order to prevent damage caused by overcharging or undercharging, the controller 60 can increase the charging margins, that is, both the minimum and maximum charging margins are increased, for the same minimum and maximum load charging power.

[0074] For example, considering that the performance and safety of the battery 21 are greatly affected by the ambient temperature, the controller 60 can adjust the minimum and maximum charging margins of the battery 21 to ensure the safety and efficiency of the battery 21 in high or low temperature environments.

[0075] For example, based on the changes in the load profile, the controller 60 can adjust the maximum and minimum charging margins to accommodate different power demands, thereby optimizing the efficiency and lifespan of the battery 21.

[0076] At block 542, the controller 60 determines a charging margin factor based on the charging margin parameters. The charging margin factor is, for example, a charging slope calculated based on the four charging margin parameters described above, and its value is between 0 and 1. The controller 60 can adjust the charging margin factor by adjusting the charging margin parameters.

[0077] At block 543, the controller 60 determines the charging power of the battery 21 based on the maximum charging power that the battery 21 can currently provide and the charging margin factor. For example, the charging power of the battery 21 is obtained by multiplying the maximum available charging power by the charging margin factor. Here, by using the charging margin factor to make the charging power of the battery 21 less than its maximum charging power, it can play a role in ensuring the charging safety of the battery 21.

[0078] At block 544, the controller 60 calculates the sum of the demand power of the load system 200 and the charging power of the battery 21.

[0079] At block 545, the controller 60 determines the power setpoint of the fuel cell 11 as the sum of the demand power of the load system 200 and the charging power of the battery 21.

[0080] If the detection result indicates that the SoC value of the battery 21 is greater than the upper limit value of the predetermined SoC range but less than the critical value, the method 500 proceeds to block 550

[0081] At block 550, the controller 60 controls the system 100 in a third operation mode. In this operation mode, the controller 60 adjusts the power setpoint of the fuel cell 11 to be lower than the demand power of the load system 200, so that the battery 21 discharges to the load system 200. In this way, a part of the demand power of the load system 200 is provided by the fuel cell 11 and another part is provided by the battery 21. Below, an example of the block 550 is described (see blocks 551-555).

[0082] With reference to Figure 6C, at block 551, the controller 60 determines discharging margin parameters of the battery 21, which include the minimum load discharging power and a corresponding minimum discharging margin, as well as the maximum load discharging power and a corresponding maximum discharging margin.

[0083] In an example, the discharging margin parameters are preconfigured based on the type of battery 21 and stored in the controller 60. This is because different types of batteries have different charging and discharging characteristics and safety requirements, so different discharging margin parameters need to be configured. Moreover, considering that relying solely on the preconfigured discharging margin parameters, which are based on the battery type, may not be sufficient to cope with discharging application scenarios, the controller 60 can adjust these parameters based on at least one of the following factors: 1) the state of health of the battery 21; 2) the ambient condition including a temperature, humidity, pressure of the battery 21; and 3) the load profile of the load system 200.

[0084] For example, as the battery 21 is used and aged, its capacity will gradually decrease and its internal resistance will increase, which will affect its discharge performance. In order to ensure that the battery 21 can still work safely and stably when its state of health declines, the controller 60 can adjust the discharge margin parameters accordingly.

[0085] For example, the performance and safety of the battery 21 are greatly affected by the ambient temperature. In high temperature environments, the chemical reactions inside the battery will accelerate, which may lead to safety issues such as overheating, leakage, and even explosion; on the other hand, while in low temperature environments, the discharge capacity of the battery 21 will significantly decrease. Therefore, the controller 60 can adjust the discharge margin parameters according to changes in ambient temperature to ensure the normal operation of the battery 21 at different temperatures.

[0086] For example, the load profile reflects the power demand of the load system 200 at different time points. If the power demand of the load system 200 fluctuates greatly or there is a sudden high load demand, the controller 60 can adjust the discharge margin parameters to cope with these changes and maintain stable power supply. By reserving larger power margins, it can ensure that thebattery 21 can still provide stable power supply when the load power demand changes, avoiding system collapse or performance degradation caused by insufficient power.

[0087] At block 552, the controller 60 determines a discharge margin factor based on the discharge margin parameters. The discharge margin factor is, for example, a discharge slope calculated based on the four discharge margin parameters described above, and its value is between 0 and 1. The controller 60 can adjust the discharge margin factor by adjusting the discharge margin parameters.

[0088] At block 553, the controller 60 determines the discharge power of the battery 21 based on the maximum discharge power that the battery 21 can currently provide and the discharge margin factor. For example, the discharge power of the battery 21 is obtained by multiplying the maximum discharge power by the discharge margin factor. Here, by using the discharge margin factor to limit the discharge power of the battery 21 to be less than its maximum allowable discharge power, it ensures the safety of the battery 21 during the discharge process.

[0089] At block 554, the controller 60 calculates a difference between the demand power of load system 200 and the discharge power of battery 21.

[0090] At block 555, the controller 60 determines the power setpoint of fuel cell 11 to be the difference between the demand power and the discharge power.

[0091] If the detection result indicates that the SoC value of the battery 21 is higher than the critical value, the method 500 proceeds to block 560.

[0092] In block 560, the controller 60 operates the system 100 in a fourth operation mode. In this operation mode, the controller 60 sets the power setpoint of the fuel cell 11 to zero. This is because the SoC value of the battery 21 is higher than the critical value, which means that the battery 21 must be discharged even when load power demand is lower than to the minimum generation thresholdof the fuel cell 11. This will cause the fuel cell 11 to turn off or enter a standby state. It should be understood that the minimum generation threshold of the fuel cell 11 is the lowest power value that the fuel cell can stably and continuously work. This value is usually determined by the design parameters, working environment, and load characteristics of the fuel cell 11. When the generated power of the fuel cell 11 is lower than this value, it cannot maintain a normal electrochemical reaction rate, resulting in performance degradation or damage.

[0093] After determining the power setpoint at block 530, 540, or 550, the method 500 proceeds to block 570.

[0094] At block 570, the controller 60 limits the power setpoint in two aspects, i.e., saturation limiting and ramp limiting. The two aspects are described in detail below (blocks 571 and 572).

[0095] With reference to Figure 6D, at block 571, the controller 60 limits the determined power setpoint by means of an upper saturation value and a lower saturation value.

[0096] The upper saturation value and the lower saturation value are used to ensure that the fuel cell 11 does not output power beyond its safe or effective operating range. That is, if the determined power setpoint is higher than the upper saturation value or lower than the lower saturation value, it will be limited by the upper saturation value or the lower saturation value.

[0097] The upper saturation value and the lower saturation value can be preset in the controller 60 or determined based on communication information with the fuel cell 11. For example, the fuel cell 11 provides real-time available maximum and minimum output power, which can be used as the upper saturation value and the lower saturation value.

[0098] With contoured reference to Figure 6D, at block 572, the controller 60 limits the power setpoint by means of a ramp limit value.

[0099] The ramp limit value is used to control the rate of change of the powersetpoint delivered to the fuel cell 11. This is because rapidly changing the power output of the fuel cell 11 may negatively affect its performance, lifetime, or stability. That is, if the rate of change of the power setpoint exceeds the ramp limit value, it will be adjusted to comply with the ramp limit value. Additionally, it can avoid the risk of instabilities in the overall control by limiting the ramp rate of the change of the power setpoint.

[0100] The ramp limit value can either be preset in the controller 60 or dynamically determined based on communication with the fuel cell 11. For example, the fuel cell 11 provides an absolute maximum rate of power change, which is determined by various factors such as the type (e.g., proton exchange membrane fuel cell, molten carbonate fuel cell, etc.), current state (e.g., temperature, pressure, humidity, etc.), and operating conditions (e.g., load demand, supply of hydrogen and oxygen, etc.) of the fuel cell 11. These factors directly affect the chemical reaction rate inside the fuel cell 11 , thereby limiting the maximum power change rate that the fuel cell 11 can safely and stably achieve.

[0101] It can be seen that by setting the upper and lower saturation values for the power setpoint and limiting the rate of change with a ramp limit value, the fuel cell 11 can operate safely, efficiently, and stably.

[0102] It should be understood that the present disclosure does not limit the execution order of block 571 and block 572. That is, both blocks can be executed simultaneously or sequentially.

[0103] At block 580, the controller 60 transfers the power setpoint to the fuel cell 11 , as the target output power of the fuel cell 11.

[0104] It should be understood that in the embodiment where the controller 60 is implemented with a multiplexer (see Figure 2 A), the controller method according to the present disclosure can be implemented in a similar manner as described above, and therefore will not be repeated here.

[0105] The previous description is provided to enable any person skilled in theart to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein. All structural and functional equivalent transformations to the elements of the various aspects of the present disclosure, which are known or to be apparent to those skilled in the art, are intended to be covered by the claims.

Claims

WHAT IS CLAIMED IS:

1. A fuel cell-based generation system comprising: a fuel cell subsystem comprising at least one fuel cell coupled to a power terminal which is configurable to connect with a load system; a battery subsystem comprising at least one battery coupled to the power terminal and configured to provide a state of charge (SoC) value of the at least one battery, the at least one battery being capable of discharging to the load system and charging from the at least one fuel cell; and a controller configured to operate the fuel cell-based generation system by coordinated control of the battery subsystem and the fuel cell subsystem, wherein the coordinated control is provided by dynamically adjusting a power setpoint of the at least one fuel cell based on the SoC value of the at least one battery.

2. The fuel cell-based generation system of claim 1, wherein the controller is configured to adjust the power setpoint of the at least one fuel cell based on a comparison of the SoC value with an upper limit value or a lower limit value of a predetermined SoC range which is preconfigured based on the type of the at least one battery.

3. The fuel cell-based generation system of claim 2, wherein the controller is configured to adjust the upper limit value and the lower limit based on one or more of:- a state of health of the at least one battery;- an ambient condition including a temperature, humidity, pressure of the at least one battery; and- a load profile of the load system.

4. The fuel cell-based generation system of claim 1, wherein the controller is configured to: in the case that the SoC value is less than a lower limit value of a predetermined SoC range, adjust the power setpoint such that the at least one battery charges from the at least one fuel cell.

5. The fuel cell-based generation system of claim 4, wherein the controller is configured to: determine a charging margin factor; determine the charging power for charging the at least one battery based on the charging margin factor and the maximum available charging power of the at least one battery; and adjust the power setpoint to be a sum of demand power of the load system and the charging power.

6. The fuel cell-based generation system of claim 5, wherein determining the charging margin factor comprises: determining the charging margin factor based on charging margin parameters comprising a minimum load charging power and a corresponding minimum charging margin, as well as a maximum load charging power and a corresponding maximum charging margin, and wherein the charging margin parameters are preconfigured based on the type of the at least one battery.

7. The fuel cell-based generation system of claim 6, wherein the controlleris configured to adjust the charging margin parameters based on one or more of:- a state of health of the at least one battery;- an ambient condition including a temperature, humidity, pressure of the at least one battery; and- a load profile of the load system.

8. The fuel cell-based generation system of claim 1, wherein the controller is configured to: in the case that the SoC value is greater than an upper limit value of a predetermined SoC range, adjust the power setpoint such that the at least one battery discharges to the load system.

9. The fuel cell-based generation system of claim 8, wherein the controller is configured to: determine a discharging margin factor; determine the discharging power for discharging to the load system from the at least one battery based on the discharging margin factor and the maximum available discharging power of the at least one battery; and adjust the power setpoint to be a difference of demand power of the load system and the discharging power.

10. The fuel cell-based generation system of claim 9, wherein determining the discharging margin factor comprises: determining the discharging margin factor based on discharging margin parameters comprising a minimum load discharging power and a corresponding minimum discharging margin, as well as a maximum load discharging power anda corresponding maximum discharging margin, and wherein the discharging margin parameters are preconfigured based on the type of the at least one battery.

11. The fuel cell-based generation system of claim 10, wherein the controller is configured to adjust the discharging margin parameters based on one or more of:- a state of health of the at least one battery;- an ambient condition including a temperature, humidity, pressure of the at least one battery; and- a load profile of the load system.

12. The fuel cell-based generation system of claim 1, wherein the controller is configured to, in the case that the SoC value is within a predefined SoC range and power demand of the load system has changed by at least a sensitivity threshold over a predetermined time period, adjust the power setpoint to the power demand.

13. The fuel cell-based generation system of claim 1, wherein the controller is configured to, in the case that the SoC value is within a predetermined SoC range, implement a battery balancing function that is able to be activated or deactivated, to perform charging and discharging power balancing of the at least one battery.

14. The fuel cell-based generation system of claim 13, wherein the controller is configured to implement the battery balancing function by: detecting a power difference between the maximum available charging power and the maximum available discharging power of the at least one battery;in the case that the detected power difference exceeds a power difference threshold, adjust the power setpoint to keep the available power of the at least one battery at a central value with respect to the maximum available charging power and the maximum available discharging power.

15. The fuel cell-based generation system of any one of claims 1-14, wherein the controller is configured to implement a saturation limit and a ramp limit on the adjusted power setpoint to limit both the value of the power setpoint and the rate of change of the power setpoint.

16. The fuel cell-based generation system of claim 1, wherein the controller is configured to: in the case that the SoC value exceeds a critical value, which results in the output power of the at least one fuel cell falling below its minimum generation threshold, causing the at least one fuel cell to turn off or enter a standby state, adjust the power setpoint to zero.

17. The fuel cell-based generation system of claim 1, wherein the controller comprises: multiple determination units each of which is configured to determine the power setpoint in the case that the SoC value is within one of multiple predetermined SoC ranges; and a multiplexer with multiple channels corresponding to the multiple determined SoC ranges, each channel having an input connected to one of the multiple determination units and an output that can be gated to connect to the at least one fuel cell.

18. The fuel cell-based generation system of claim 17, wherein the multiple predetermined SoC ranges comprise: a predetermined SoC range having an upper limit value and a lower limit value; a low SoC range within which SoC values are less than the lower limit value; a first high SoC range within which SoC values are greater than the upper limit value and less than a critical value which is greater than the upper limit value; and a second high SoC range within which SoC values are greater than the critical value.

19. The fuel cell-based generation system of claim 1, wherein the at least one fuel cell is coupled to the at least one battery and the power terminal through a power electronics circuit that optionally includes at least one transformer.

20. A method for controlling a fuel cell-based generation system, the fuel cell-based system comprising: a fuel cell subsystem comprising at least one fuel cell coupled to a power terminal which is configurable to connect with a load system; and a battery subsystem comprising at least one battery coupled to the power terminal and configured to provide a state of charge (SoC) value of the at least one battery, the at least one battery being capable of discharging to the load system and charging from the at least one fuel cell; the method comprising: operating the fuel cell-based generation system by coordinated control of the battery subsystem and the fuel cell subsystem, wherein the coordinated control isprovided by dynamically adjusting a power setpoint of the at least one fuel cell based on the SoC value of the at least one battery.

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