Systems and methods for providing thermal control in multi-stack fuel cell systems

Abstract

Systems and methods for providing heat control in a multi-stack fuel cell system. The present disclosure relates to a system (5) comprising a plurality of power converters (20-1 to 20-n) configured to balance heat from a plurality of fuel cell stacks (10-1 to 10-n) via a processing device (30). Some embodiments may: set one or more parameter values for one of the power converters (20-1) located at an output of one of the plurality of stacks (10-1) such that one stack preferentially provides power to a load; determining thermal powers of the one stack (10-1) and one or more other stacks of the plurality of stacks (10-2 to 10-n), each of the thermal powers being determined based on the voltage and current determined at the input of the respective power converter (20-1 to 20-n); determining whether the thermal power of one stack (20-1) meets a criterion; and in response to determining that the thermal power of one stack meets the criteria, setting one or more parameter values for each of the power converters (20-2 to 20-n) located at the output of one or more other stacks, the determined thermal power of each of the one or more other stacks (10-2 to 10-n) is closer to the determined thermal power of the one stack (10-1) in such a way that the determined thermal power of each of the one or more other stacks (10-2 to 10-n) matches the determined thermal power of the one stack (10-1).

Description

Systems and methods for providing thermal control in multi-stack fuel cell systems

[0001] This application is a divisional application of Chinese patent application 202080083130.X, filed on October 8, 2020, entitled "System and method for providing thermal control in a multi-stack fuel cell system". Technical Field

[0002] This disclosure generally relates to systems and methods for controlling fuel cell stacks and corresponding power converters to ensure that the fuel cell stacks degrade at substantially the same rate. Background Technology

[0003] A fuel cell stack consists of many individual cells stacked together, such that the cathode of one cell is electrically connected to the anode of the adjacent cell. In this way, the exact same current flows through each cell. Efficient fuel cell power requires proper temperature control and thermal management to ensure reliable operation. For example, higher operating temperatures often lead to more water being evaporated, generating more waste heat, which risks damaging the fuel cell stack (e.g., membrane drying) and / or accelerating performance degradation.

[0004] Even new fuel cell stacks vary in performance due to their manufacturing tolerances and individual operating methods. Over time, stacks degrade, but their performance doesn't degrade at the same rate, even when the electrical load is evenly distributed among all stacks. The stacks degrade at different rates, causing the weakest or worst-performing stack to increasingly take on more of its own and work proportionally to keep up with the others. Further degradation of the fuel cell stack occurs in situations such as runaway states or negative feedback loops, where the stack deteriorates rapidly, leading to a significantly shortened lifespan for the entire system. Simply further cooling the weakest stack is not a viable solution because of the quadratic relationship: doubling the airflow from the fan consumes four times the parasitic power. Summary of the Invention

[0005] Systems and methods for controlling heat generation in multiple fuel cell stacks are disclosed. Therefore, one or more aspects of this disclosure relate to methods for configuring multiple power converters to achieve thermal balance. Some embodiments may: set one or more parameter values ​​for one of the power converters located at the output of one of the multiple stacks such that one stack preferentially provides power / supply to a load; determine the thermal power of said one stack and one or more other stacks, each of the thermal powers being determined based on voltage and current determined at the input of the respective power converter; determine whether the thermal power of said one stack meets a criterion; and in response to determining that the thermal power of said one stack meets the criterion, set one or more parameter values ​​for each of the power converters located at the output of one or more other stacks such that the determined thermal power of each of the one or more other stacks more closely matches the determined thermal power of one stack.

[0006] This method is implemented by a system comprising one or more hardware processors configured with machine-readable instructions and / or other components. The system includes one or more processors and other components or media, such as on which machine-readable instructions can be executed. Implementations of any of the techniques described may include methods or processes, apparatus, devices, machines, systems, or instructions stored on one or more computer-readable storage devices. Attached Figure Description

[0007] Details of specific embodiments are set forth in the following figures and description. Throughout this specification, similar reference numerals may refer to similar elements. Other features will be apparent from the following description, including the figures and claims. However, the figures are for illustrative and descriptive purposes only and are not intended to be construed as limiting the scope of this disclosure.

[0008] Figure 1 illustrates an example of a system for balancing the heat generated by a fuel cell stack according to one or more embodiments.

[0009] Figure 2 illustrates a process for balancing the heat generated by a fuel cell stack according to one or more embodiments. Detailed Implementation

[0010] As used herein, the word “may” is used in a permissive sense (i.e., meaning possible), not in a mandatory sense (i.e., meaning mandatory). The words “include,” “including,” “includes,” etc., mean including, but are not limited to. As used herein, the singular forms “a / an” and “the” include plural references unless the context clearly indicates otherwise. As used herein, the term “number” should mean one or more integers (i.e., multiples).

[0011] As used herein, the statement that two or more parts or components are “coupled” means that, whenever a link occurs, these parts are engaged or operate together, directly or indirectly, i.e., through one or more intermediate parts or components. As used herein, “direct coupling” means that two elements are in direct contact with each other.

[0012] Unless otherwise expressly stated, it is obvious from the discussion that, throughout the specification, the use of terms such as “processing,” “computing,” “calculating,” and “determining” refers to the actions or processes of a particular device, such as a dedicated computer or similar dedicated electronic processing / computing equipment.

[0013] Figure 1 illustrates a multi-stack fuel cell power system 5 including a power converter 20 configured to, at a given moment, cause a group of stacks 10 to follow the heat generated by one of the stacks 10. At this time, this stack may be designated as the master stack. Moreover, although electrical load limits (e.g., rate of change limits) can be set for this stack, it effectively follows the load. The remaining stacks can be controlled based on a heat setpoint to be achieved, which can be derived from the heat generated by the master stack. At a subsequent time, another stack in the group can be designated and controlled as the master stack.

[0014] In some embodiments, the outputs of the power converters 20 of system 5 are connected in a parallel configuration, such that stacks 10⁻¹ to 10⁻ⁿ (where n is a natural number) provide power to the load. In some embodiments, the power converters 20 are DC-DC (DC / DC) converters, which include electronic circuitry or electromechanical devices that convert a direct current (DC) source from one voltage level to another. For example, each power converter 20 may be a DC / DC buck-boost converter, a linear regulator, a voltage regulator, a motor generator, a rotary converter, or a switch-mode power supply. In some embodiments, the outputs of the power converters 20 are regulated. Furthermore, in some embodiments, the power provided to the load may be linear, switched, or battery-based.

[0015] In some embodiments, each power converter 20 has one or more analog inputs, such as voltage setpoints and current limits, for controlling the output power from each power converter. For example, power control component 32 may set the voltage of each power converter 20-2 to 20-n (where n is a natural number) to a higher voltage setpoint than that of power converter 20-1, thereby preferentially feeding power converters 20-2 to 20-n to the load. In this example, power control component 32 may configure power converter 20-1 as the master stack by setting its current limit to a higher current limit than that of power converters 20-2 to 20-n. When load demand meets the criteria, and therefore when a considerable amount of power is drawn from system 5, stack 10-1 and power converter 20-1 may participate in supplying the excess power demand. However, because heat estimation component 34 can determine the heat power generated from each stack 10, power control component 32 may increase the current limit of each power converter 20-2 to 20-n, causing power converters 20-2 to 20-n to deliver more power. In some implementations, the heat estimation component 34 may determine these heat powers periodically or irregularly. In another implementation, the heat estimation component 34 may determine these heat powers based on requests received from a user via the user interface 18.

[0016] In some embodiments, the power control component 32 can configure one stack 10 as the master stack by specifically controlling the output current limit and voltage setpoint of the power converter 20. In some embodiments, the power control component 32 can configure stack 10 as master to supply transient loads by following the power cycle. In some embodiments, the power control component 32 alternates between using one of the stacks 10 as the master stack. In some embodiments, more than one stack can operate as the master stack. In any of these cases, other stacks not currently operating as the master stack can increase or decrease their power generation / generation to follow the heat generation of the master stack.

[0017] In some embodiments, the power control component 32 may configure the weakest or least healthy stack 10 as the master stack. In these or other embodiments, the power control component 32 may configure the strongest or healthiest stack 10 as the master stack. The master stack typically follows the load. For example, if the load is zero, the master stack and all other stacks may not provide power; however, as the load increases, the power converter of the master stack may follow the load. That is, the power of the master stack may increase as quickly as possible to match the load. In practice, all stacks 10 in System 5 may follow the load by providing power accordingly, but the master stack may lead, and the other stacks may follow the master stack. However, this may not mean that the master stack 10 will exceed the level of equal sharing. Stacks 10 other than the master stack 10 may follow the master stack, such that they attempt to match the master stack's thermal power (or other matching parameters) and follow behind. In another example, the master stack may be inactive (while all other stacks are actively acquiring power) until the demand from the load rises above a threshold.

[0018] The electronic storage device 22 of Figure 1 includes an electronic storage medium for storing information electronically. The electronic storage medium of the electronic storage device 22 may include a system storage device integrated with (i.e., substantially non-removable) the system 5 and / or a removable storage device detachably connected to the system 5 via, for example, a port (e.g., a USB port, a FireWire port, etc.) or a drive (e.g., a disk drive, etc.). The electronic storage device 22 may be (wholly or partially) a separate component within the system 5, or the electronic storage device 22 may be (wholly or partially) integrated with one or more other components of the system 5 (e.g., user interface device 18, processor 30, etc.). In some embodiments, the electronic storage device 22 may be located in a server along with the processor 30, in a server as part of external resource 24, in the user interface device 18, and / or in other locations. Electronic storage device 22 may include a storage controller and one or more optically readable storage media (e.g., optical discs, etc.), magnetically readable storage media (e.g., magnetic tape, magnetic hard disk drives, floppy disk drives, etc.), charge-based storage media (e.g., EPROM, RAM, etc.), solid-state storage media (e.g., flash drives, etc.), and / or other electronically readable storage media. Electronic storage device 22 may store software algorithms, information obtained and / or determined by processor 30, information received via user interface device 18 and / or other external computing systems, information received from external resources 24, and / or other information enabling system 5 to function as described herein.

[0019] External resources 24 may include information sources (e.g., databases, websites, etc.), external entities participating in system 5, one or more servers outside system 5, networks, electronic storage devices, equipment related to Wi-Fi technology, equipment related to Bluetooth® technology, data input devices, power supplies, transmitting / receiving elements (e.g., antennas configured to transmit and / or receive wireless signals), network interface controllers (NICs), display controllers, graphics processing units (GPUs), and / or other resources. In some embodiments, some or all of the functionality attributed herein to external resources 24 may be provided by other components or resources included in system 5. The processor 30, external resources 24, user interface device 18, electronic storage device 22, network 70 and / or other components of system 5 may be configured to communicate with each other via wired and / or wireless connections such as networks (e.g., local area network (LAN), Internet, wide area network (WAN), radio access network (RAN), public switched telephone network (PSTN)), cellular technologies (e.g., GSM, UMTS, LTE, 5G, etc.), Wi-Fi technology, another wireless communication link (e.g., radio frequency (RF), microwave, infrared (IR), ultraviolet (UV), visible light, centimeter wave (cmWave), millimeter wave (mmWave), etc.), base stations and / or other resources.

[0020] User interface devices (one or more) 18 of System 5 may be configured to provide an interface between System 5 and one or more users. User interface devices 18 are configured to provide information to and / or receive information from one or more users. User interface devices 18 include user interfaces and / or other components. The user interface may be and / or include a graphical user interface configured to present views and / or fields configured to receive input and / or selections regarding specific functionality of System 5, and / or provide and / or receive other information. In some embodiments, the user interface of user interface device 18 may include multiple separate interfaces associated with processor 30 and / or other components of System 5. Examples of interface devices suitable for inclusion in user interface device 18 include touchscreens, keypads, touch-sensitive and / or physical buttons, switches, keyboards, knobs, levers, displays, speakers, microphones, indicator lights, audible alarms, printers, and / or other interface devices. This disclosure also contemplates user interface device 18 including a removable storage interface. In this example, information can be loaded from a removable storage device (e.g., a smart card, a flash drive, or a removable disk) into the user interface device 18, which allows the user to customize the implementation of the user interface device 18.

[0021] In some embodiments, user interface device 18 is configured to provide system 5 with a user interface, processing power, database, and / or electronic storage device. Therefore, user interface device 18 may include processor 30, electronic storage device 22, external resources 24, and / or other components of system 5. In some embodiments, user interface device 18 is connected to a network (e.g., the Internet). In some embodiments, user interface device 18 does not include processor 30, electronic storage device 22, external resources 24, and / or other components of system 5, but communicates with these components via dedicated lines, buses, switches, networks, or other communication tools. Communication may be wireless or wired. In some embodiments, user interface device 18 is a laptop computer, desktop computer, smartphone, tablet computer, and / or other user interface device.

[0022] Data and content can be exchanged between various components of System 5 via communication interfaces (such as hardwired, bus, etc.) and communication paths, using any of a variety of communication protocols corresponding to different media delivery platforms.

[0023] In some embodiments, processor 30 may belong to a user device, consumer electronics device, mobile phone, smartphone, personal data assistant, digital tablet computer / tablet computer, wearable device (e.g., watch), personal computer, laptop computer, notebook computer, workbench, server, high-performance computer (HPC), in-vehicle computer, gaming or entertainment system, set-top box, or any other device. Therefore, processor 30 is configured to provide information processing capabilities in system 5. Processor 30 may include one or more of a microcontroller, digital processor, analog processor, digital circuitry designed for processing information, analog circuitry designed for processing information, state machine, and / or other mechanisms for electronically processing information. Although processor 30 is shown as a single entity in FIG. 1, this is merely for illustrative purposes. In some embodiments, processor 30 may include multiple processing units. These processing units may be physically located within the same device (e.g., a server), or processor 30 may represent the processing functionality of multiple devices operating collaboratively (e.g., one or more servers, user interface device 18, devices as part of external resource 24, electronic storage device 22, and / or other devices).

[0024] As shown in Figure 1, processor 30 is configured via machine-readable instructions to execute one or more computer program components. The computer program components may include one or more of a power control component 32, a heat estimation component 34, a cooling control component 36, a switch control component 38, a valve control component 39, and / or other components. Processor 30 may be configured to execute components 32, 34, 36, 38, and / or 39 via: software; hardware firmware; a combination of software, hardware, and / or firmware; and / or other mechanisms for configuring processing capabilities on processor 30.

[0025] It should be understood that although components 32, 34, 36, 38, and 39 are shown in FIG. 1 as co-located within a single processing unit, in embodiments where processor 30 includes multiple processing units, one or more of components 32, 34, 36, 38, and / or 39 may be located remotely from other components. For example, in some embodiments, each of processor components 32, 34, 36, 38, and 39 may include a set of independent and distinct processors. The description of the functionality provided by the different components 32, 34, 36, 38, and / or 39 described below is for illustrative purposes and not for limitation, as any of components 32, 34, 36, 38, and / or 39 may provide more or less functionality than described. For example, one or more of components 32, 34, 36, 38, and / or 39 may be eliminated, and some or all of their functionality may be provided by other components 32, 34, 36, 38, and / or 39. As another example, processor 30 may be configured to execute one or more additional components that can perform some or all of the functionality attributed to one of components 32, 34, 36, 38 and / or 39.

[0026] In some embodiments, the power control component 32 may determine the number of stacks 10 and the specific stack 10 currently operating in system 5, such that various combinations of stacks 10 are used to supply power to the load. For example, the power control component 32 and the heat estimation component 34 may result in the creation of a configuration (one or more) of an operating power converter 20 for feeding power to the load. In this or another example, a switch may be configured such that the load draws power from one or more of stacks 10-1, 10-2, ... 10-n. In some embodiments, the load comprises multiple loads.

[0027] In some embodiments, the power control component 32 may be configured to identify and automatically determine one or more parameter values ​​for each power converter 20. These parameter values ​​may include at least one of current limit, voltage setpoint, on / off setting, and another suitable control signal. By controlling these parameter values, the power converter 20 may be under the full power control of the power control component 32. In some embodiments, the power converter 20 may determine its own output voltage among itself based on the desired input voltage received via the user interface 18 and transmitted to the respective power converter 20 via a voltage control signal from the power control component 32.

[0028] In some embodiments, the power control component 32 may set a maximum current limit and / or voltage setpoint for each power converter 20 in system 5. For example, power converter 20-1 may be set to deliver power at 48 volts (V), and one or more power converters 20-2 to 20-n may be set to deliver power at 49 volts. However, this is not intended to be limiting, as each of the one or more power converters may be individually configured and therefore set to different and potentially different currents and / or voltages.

[0029] In some embodiments, the power control component 32 may configure one or more power converters 20 such that one or more stacks 10 operate as a master stack. In some embodiments, the power control component 32 may receive the voltage setting of the master stack of the system 5 as input via the user interface device 18. The power control component 32 may then configure the output voltage of the power converter associated with that stack based on the received voltage, and configure the output voltage of the power converters associated with all other stacks of the system 5 to be slightly higher than the output voltage associated with the master stack. With this configuration, other stacks will be fed preferentially. That is, by setting a lower setpoint than other stacks, the master stack 10 will allow other stacks 10 to be fed first. However, by setting the current limit of the power converter 20 of the master stack to be higher than the current limit of the power converter 20 of other stacks, the power converters of the master stack can facilitate the delivery of more current to the load when an additional load needs to be ripped.

[0030] In some implementations, the power control component 32 can control the power converters 20 associated with the master stack 10, causing the master stack to preferentially provide power until it becomes too hot; that is, the master stack can be configured to follow the load. When the master stack 10 becomes too hot, other stacks 10 can be configured to help and remove some load to lower the temperature of the master stack by controlling their power converters. Thus, each stack 10 can be controlled to take turns being the master stack. With this control strategy, some embodiments of system 5 can avoid weak stack exhaustion. When a weak stack is in the master stack, it may heat up faster, so other stacks can be controlled to activate earlier to assist.

[0031] In some embodiments, instead of requiring all stacks 10 to provide an equal proportion of electrical load, one stack 10 may be designated as the master stack. The effect of this is that a higher-performing stack may work slightly harder than the others, thus distributing performance degradation more evenly across all stacks. Furthermore, since they may generate the same amount of heat, they may require the same cooling and therefore may operate with the same cooling flow (e.g., via gas, air, liquid, or other media).

[0032] When the fuel cell is operating, the electrolytic oxidation of hydrogen generates a voltage that drives a current to provide useful power. However, this production is not entirely efficient, thus generating waste heat. The heat estimation component 34 performs calculations to provide an estimate of the thermal power. In some embodiments, the thermal power may be the power from a reaction (i.e., the reversible electrochemical reaction that occurs in the fuel cell to produce water via hydrogenation), which is not efficiently converted into electricity but rather into heat. This thermal power (P...) 热 The following equation can be used to generate it: (1) In this equation, N 电池 It is the number of cells (e.g., proton exchange membrane (PEM) fuel cells) in the stack, Δ c H LHV It is the heat of combustion of hydrogen (LHV) and is measured in megajoules (MJ) per kilogram (kg). H2 is the molecular mass of hydrogen measured in grams (g) per mole, s is the amount of substance used / produced in the reaction (e.g., hydrogen consumed), z is the number of electrons used in the reaction (e.g., 2), F is the Faraday constant measured in coulombs (C) per mole, and V 堆栈 I is the output voltage setpoint of the stack and is measured by voltage sensor 40, and I is the current drawn from the stack and is measured by current sensor 50. Equation 1 above can be simplified to the following equation by replacing the constant with the corresponding values: (2) The value 1.253169873 can be regarded as the ideal low heating value (LHV) voltage.

[0033] In some embodiments, the heat estimation component 34 may implement a stack-based estimated health status implementation of a general strategy for selecting a base stack 10. For example, the heat estimation component 34 may be configured to store previously determined heat power for each stack 10 and determine the health level of each stack 10 based on the stored (i.e., historical) heat power for each stack. In this or another example, the power control component 32, using one or more values ​​from the heat estimation component 34, may be configured to reset the parameter values ​​of a power converter (e.g., 20-1) associated with a primary stack (e.g., 10-1) based on the corresponding, determined health level, and reset the parameter values ​​of another power converter (e.g., one of 20-2 to 20-n) associated with another stack (e.g., one of 10-2 to 10-n), such that the other stack preferentially provides power to the load. The power control component 32 and the heat estimation component 34 can thus be configured for this change in the primary stack; as a result, another stack may degrade at a now greater rate (e.g., by operating the other stack via the configuration of the corresponding power converter, such that the other stack is hotter than if the other stack had not been selected to reset its parameter values(s)).

[0034] Processor 30 can load values ​​from electronic storage device 22, learn optimal values, and then store these new values ​​in electronic storage device 22. These values ​​may include thermal power, parameter values ​​for controlling power converter 20, values ​​for controlling cooling equipment 60, values ​​from sensors 55, 56, 40, 41, 50, 51 and / or one or more other devices, total power-on time after power-on, total energy generated, and / or other suitable values. One or more of these values ​​can be read from electronic storage device 22 at startup. Once running, processor 30 can record these values ​​to electronic storage device 22 or another destination.

[0035] In some embodiments, the cooling control component 36 may send control signals to each of a group of fans, impellers, and / or pumps. In some embodiments, the cooling control component 36 may use the output values ​​of thermistors 55-56 to control the cooling apparatus 60. Therefore, fan control may heavily rely on thermal power, which is the heat required for fan cooling. For example, by using power control component 32 and thermal estimation component 34 together to match the thermal power of the main stack 10, the cooling control component 36 may use temperature sensors 55-56 to effectively match airflow and fan controls. Since fan power is quadratically related to airflow, the most efficient (and quietest) point may be when airflow is matched. Each of thermistors 55 (e.g., 55-1, 55-2, ... 55-n) may be placed before the stack 10, for example, at or near the airflow duct. And each thermistor 56 (e.g., 56-1, 56-2, ... 56-n) may be placed after the stack 10, for example, at the other end of the airflow duct. In some embodiments, the cooling apparatus 60 may be coupled to the stack 10. For example, cooling equipment 60 may include a set of fans, impellers, and / or pumps located at or near stack 10, such as at the rear (or front) of system 5. Cooling equipment 60 (e.g., 60-1, 60-2, ... 60-n) may exhaust air, hydrogen, and / or water vapor. Some embodiments of system 5 may reduce production costs by placing stack 10 in an airflow, a box, and / or a hydrogen feed into it.

[0036] Known fuel cell stack cooling systems include a fixed maximum airflow for each stack. Therefore, if a system has multiple units, each with the same airflow and operating at maximum power, then each stack must withstand the same amount of heat. Any power demand exceeding this maximum load can cause the stacks to operate hotter, but these stacks cannot dissipate the excess heat, thus exposing them to a greater risk of damage and a shorter lifespan. In some embodiments, power control component 32 controls power converter 20 such that the amount of cooling required for each stack 10 is balanced. Thus, some embodiments may have uniformly operating cooling equipment 60 (e.g., through approximately the same amount of airflow when using fans), resulting in lower parasitic power consumption (i.e., due to the way nonlinear terms in the control equations operate) compared to the consumption of one higher-operating cooling equipment and another lower-operating cooling equipment. Therefore, even at non-maximum power, some embodiments of system 5 can have the same cooling (e.g., operating at the same or similar fan speeds) because the heat generated by each of the stacks 10 is the same, resulting in minimal parasitic power consumption. Therefore, some embodiments of system 5 may balance the fan speeds.

[0037] In some embodiments, the power control component 32 can control each power converter 20, and the heat estimation component 34 can monitor the temperature of each stack 10. Through this combined approach, if a stack 10 becomes too hot, the power control component 32 can reduce the heat generation of that stack 10. For example, the power control component 32 can induce this reduction from one stack by controlling an increase in heat generation from one or more other stacks 10, thereby effectively balancing thermal power. In this or another example, the power control component 32 and the heat estimation component 34 can balance the heat generated from the stacks 10 by exchanging one stack 10 with another as a master stack or as a stack powering a parasitic load. The temperature that a hot stack 10 experiences or operates at may be proportional to its degradation, such that the hotter the stack, the more severe the degradation it may experience. Some embodiments of the power control component 32 and the heat estimation component 34 can therefore control and reduce degradation by dynamically balancing the heat between the stacks 10.

[0038] Some embodiments of processor(s) 30 may include a balancing algorithm that requires power to implement. For example, during the startup phase, processor 30 may draw power from battery 16 via a closed switch. That is, when switched on, the load and / or processor 30 may consume power from battery 16. For example, system 5 may include a switch controlled by switch control component 38 such that processor 30 stops receiving power from the battery by opening the switch at the end of the power-on phase. That is, in this or another example, system 5 may include a plurality of other switches controlled by switch control component 38 such that processor 30 begins to draw power from one or more of stacks 10-1, 10-2, ... 10-n by closing the other switches at the end of the power-on phase. Each of these other switches may be connected between one of diodes 45 and processor 30. In some embodiments, switch control component 38 may configure other switches such that stack 10 shares the parasitic load. In other embodiments, switch control component 38 may configure other switches such that one of stacks 10 supplies power to the parasitic load. In these other embodiments, the switch control component 38 may be configured with additional switches such that the stack and power converter combination is used to alternately power parasitic loads.

[0039] Some embodiments of System 5 may include switches for alternating stacks that deliver these voltage levels to the cooling equipment 60. Therefore, since one stack (e.g., 10-1) can be used to power such equipment, which may consume, for example, 200 watts (W), this one stack may degrade faster than the others 10. In some embodiments, the cooling control component 36, the switch control component 38, and / or the power control component 32 (i.e., via parameter settings of the power converter 20) can thus be shifted around the source of power supply to the cooling equipment 60 from the stacks 10 (e.g., another stack 10-2 may then take over from stack 10-1 to power this parasitic load). For System 5, having at least one power converter 20 for each stack 10 to better control the power from each stack is an important aspect of this disclosure.

[0040] The number and specific stacks of stack 10 can be controlled by processor 30. In some embodiments, power control component 32 can determine from this number and these stacks by turning switches on and / or off, such that various different combinations of stack 10 are utilized when power is fed to processor 30. In some embodiments, a power line may extend from the output of diode 45 to processor 30 via a set of switches. In this or another example, a power line may extend from the output of power converter 20 (or from the output of current sensor 51) to processor 30 via switches. In some embodiments, power control component 32 determines the sharing of parasitic loads (e.g., power consumption at processor 30 and other components, such as cooling equipment 60, sensors 55, 56, 40, 41, 50, 51 and / or one or more other devices).

[0041] In some embodiments, each of the plurality of diodes (e.g., 45-1, 45-2, ... 45-n) may be located at or near the input of each power converter 20.

[0042] In some embodiments, system 5 may include a set of current sensors (e.g., 50-1, 50-2, ... 50-n), each current sensor located at the input of each power converter 20, and each current sensor 50 configured to determine the current passing through the corresponding sensor. In some embodiments, system 5 may include another set of current detectors (e.g., 51-1, 51-2, ... 51-n), each current detector located at the output of each power converter 20, and each current sensor 51 configured to determine the current passing through the corresponding sensor. In some embodiments, system 5 may include a set of voltage sensors (e.g., 40-1, 40-2, ... 40-n) located at or near the output of each fuel stack 10, each voltage sensor 40 configured to determine the voltage relative to its respective mounting location. In some embodiments, system 5 may include another voltage sensor 41 located at a shared, parallel output of the power converter 20, the voltage sensor 41 being configured to determine the voltage relative to its mounting location. Each of the voltage sensing devices 40-41 may be a voltmeter, an analog multimeter, a digital multimeter, or another device configured to measure voltage (i.e., potential) and transmit its reading to the processor 30.

[0043] In some embodiments, when the heat generated by the main stack 10 meets a criterion, the power control component 32 may increase one or more of the current limit and voltage setpoint of one or more power converters 20. In these or other embodiments, when the heat generated by the main stack meets a criterion, the power control component 32 may decrease one or more of the current limit and voltage setpoint of one or more power converters 20. In some embodiments, the thermal power of the fuel cell stack 10 may be matched by balancing the power settings (e.g., current, voltage, etc.) between the power converters 20.

[0044] In some embodiments, when multiple stacks 10 are used, some embodiments may configure some stacks 10 to preferentially feed power to the load, for example, when one (or more) other stacks 10 are not in operation. For example, power control component 32 may increase power generation from one or more stacks 10-2 to 10-n. In this or another example, power control component 32 may decrease power generation from one or more stacks 10-2 to 10-n. That is, by preferentially feeding power through stacks 10-2 to 10-n and power converters 20-2 to 20-n, it may result in a reduction in power fed via main stack 10-1 and power converter 20-1. In some embodiments, the power drawn by power converters 20-2 to 20-n may be adjusted such that the heat generated at each of the stacks 10-2 to 10-n associated with each of the power converters 20-2 to 20-n becomes closer to or becomes the same as the heat generated at stack 10-1 associated with power converter 20-1. For example, power control component 32 may set one or more parameter values ​​for power converters 20-2 to 20-n, causing the heat of stacks 10-2 to 10-n to increase to balance or match the heat of stack 10-1. In another example, power control component 32 may set one or more parameter values ​​for power converters 20-2 to 20-n, causing the heat of stacks 10-2 to 10-n to decrease to balance or match the heat of stack 10-1.

[0045] In some embodiments, the heat estimation component 34 may determine the amount of heat being delivered by each fuel cell stack 10. When stack 10-1 is designated as the master stack, the power control component 32 may extract at least a nominal amount of heat from one or more other stacks 10-2 to 10-n based on the determination made by the heat estimation component 34. For example, to achieve this, the power control component 32 may cause an increase in the maximum current consumption limit for one or more power converters 20-2 to 20-n.

[0046] In some embodiments, the thermal follower stack 10 is not necessarily part of the same system as the main stack. In some embodiments, one or more stack systems may be installed adjacent to each other. In this embodiment, one stack system may act as the main stack, and the remaining stack systems (one or more) may follow. This is advantageous, for example, when all stack systems experience the same cooling flow rate, such as when a single cooling fan / pump controls the cooling flow rate to multiple stacks. In some embodiments, the cooling control component 36 may implement a temperature-based control strategy via ducts in which or associated with cooling activity occurs, by naturally balancing any differences in cooling.

[0047] In some embodiments, the control strategy may cause all thermal follower stacks 10 to reach the same hot spot, which may be equal to the heat generated by the master stack. In some embodiments, this approach may become undesirable after prolonged operation. For example, thermal follower stacks 10 may experience different conditions, resulting in different levels of (e.g., reversible) temporary or permanent energy loss (e.g., due to dryness or another fault condition). In this or another example, offsetting or scaling the thermal setpoint for at least one thermal follower stack 10 may enable the stack to recover from performance loss.

[0048] Because the primary stack experiences a higher instantaneous load than the thermal follower stack 10, it may degrade faster or regulate better. To ensure wear / condition leveling, the power control component 32 and / or the thermal estimation component 34 may periodically reassign which stack is the primary stack. These reassignments may be based on elapsed time or on other metrics, such as the current primary stack's performance in standardized tests.

[0049] In some embodiments, the voltage output from each stack 10 may vary depending on current consumption. For example, based on the polarization diagram, the cells in the stack may operate at 1.0 volts (V) when there is no load. And, when there is load consumption, such as several amperes (A), the voltage of each cell in the stack 10 may be 0.65 V. For example, each stack 10 of the fuel cell may output an open-circuit voltage of 48 V (or 24 V or another suitable voltage, i.e., depending on the current application).

[0050] In some embodiments, the current sensor 51 can be used to confirm that the power converter 20 is functioning correctly. In these or other embodiments, the current sensor 51 can be used to calculate the output power and / or power converter losses. In some embodiments, the current sensor 51 may not be used in the disclosed thermal following method, except in a system where the current sensor 50 is not present. In these later embodiments, the output power of the power converter 20 can be determined by multiplying the voltage measured at the voltage sensor 41 by the output current measured at the current sensor 51. Assuming a particular power converter efficiency, this output power and input voltage measured at the voltage sensor 40 can be used to estimate the current of the stack 10.

[0051] In some embodiments, system 5 may include a software-based observer (SBO) or hardware-based observer (HBO) safety circuitry (not shown). This circuitry may be a processor or microcontroller used to monitor signals and detect any safety-related faults in these signals. For example, the entire control software may not need to be certified, documented, or written to the same quality. Monitored signals may include fuel / hydrogen inlet pressure, printed circuit board (PCB) temperature, and / or differential pressure on stack 10 used to indicate gas flow. When the valve is closed, these may, among other functionalities, detect overheating, undertemperature, low gas flow, overpressure, and pressure rise.

[0052] In some embodiments, power converter 20 may support any input voltage (e.g., a range of 20 to 60 V, 9 to 60 V, or another suitable range). In some embodiments, power converter 20 may support any output voltage (e.g., about 48 V, about 24 V, or another suitable voltage). In some embodiments, power converter 20 may support any current consumption (e.g., about 40 A or another suitable ampere). In some embodiments, another power converter (not shown) may support different output voltages (e.g., 5.0 V and 3.3 V) for powering the intake valve, purge valve, louver motor, various sensors disclosed herein, processor 30, and SBO circuitry. In some embodiments, valve control assembly 39 may be configured to control one or more of these valves (not shown). Thus, processor 30 may be configured to control or otherwise interface with a power plant auxiliary facility (BOP), which refers to all support components and auxiliary systems (e.g., other than stack 10 and power converter 20) required by system 5 to deliver energy to the load.

[0053] In some embodiments, power converter 20-1 is identical to each of the other power converters (e.g., 20-2 to 20-n) in system 5. In these or other embodiments, power converter 20-1 differs from at least one of the other power converters 20 in the system.

[0054] In some embodiments, external resource 24 and / or user interface device 18 may further include interfaces (not shown) for communication, such as a controller area network (CAN) for user communication, inter-system communication and diagnostics, and a stack interface board (SIB) for internal communication to provide battery voltage information and temperature measurement.

[0055] Figure 2 illustrates a load balancing method 100 for multiple fuel cells based on thermal management according to one or more embodiments. Method 100 can be executed by a computer system including one or more computer processors and / or other components. The processor is configured with machine-readable instructions to execute computer program components. The operation of method 100 given below is illustrative. In some embodiments, method 100 may be implemented by one or more additional operations not described, and / or without requiring one or more operations discussed. Furthermore, the order of operations of method 100 shown in Figure 2 and described below is not limiting. In some embodiments, method 100 may be implemented in one or more processing devices (e.g., digital processors, analog processors, digital circuits designed for processing information, analog circuits designed for processing information, state machines, and / or other mechanisms for electronically processing information). The processing device may include one or more devices that perform some or all of the operations of method 100 in response to instructions stored electronically on an electronic storage medium. The processing device may include one or more devices configured by hardware, firmware, and / or software that are specifically designed to perform one or more operations of method 100.

[0056] In operation 102 of method 100, parameter values ​​(one or more) of a power converter located at the output of one of a plurality of fuel cell stacks may be set such that the stack preferentially supplies power to the load. For example, power control component 32 (as shown in FIG1 and described herein) may set voltage levels, current limits, and / or turn on a power converter (e.g., 20-1) such that a stack (e.g., 10-1) associated with that power converter operates as the master stack. In this or another example, power control component 32 (as shown in FIG1 and described herein) may set voltage levels, current limits, and / or turn on power converters (e.g., 20-2 to 20-n) from each other. In some embodiments, operation 102 is performed by another processor component that is the same as or similar to power control component 32.

[0057] In operation 104 of method 100, the thermal power of one of a plurality of stacks, as well as one or more other stacks, can be determined based on voltage and current, which can be determined at the input of the respective power converter. For example, the thermal power of stack 10 can be determined using Equation 1 or Equation 2 (as described above). In this example, each stack 10 may have a power converter 20 at its output. In some embodiments, operation 104 is performed by the same or similar processor component as the thermal estimation component 34 (shown in FIG. 1 and described herein).

[0058] In operation 106 of method 100, it can be determined whether the thermal power of a stack meets one or more criteria. For example, the thermal power of stack 10-1 can be compared with a threshold. If the thermal power exceeds the threshold, operation 108 can be performed. Otherwise, if the thermal power is less than or equal to the threshold, operation 104 can be performed again. In some embodiments, operation 106 is performed by the same or similar processor component as the thermal estimation component 34 (shown in FIG. 1 and described herein).

[0059] In operation 108 of method 100, parameter values ​​(one or more) of each power converter located at the output of one or more other stacks may be set such that a given thermal power of each of the one or more other stacks more closely matches a given thermal power of one stack. For example, power control component 32 (shown in FIG1 and described herein) may set voltage levels and current limits for each other power converter (e.g., 20-2 to 20-n) such that the associated stack (e.g., 10-2 to 10-n) follows the thermal generation of a master stack. In some embodiments, operation 108 is performed by another processor component that is the same as or similar to power control component 32.

[0060] The techniques described herein can be implemented in digital electronic circuits or in computer hardware, firmware, software, or combinations thereof. These techniques can be implemented as computer program products, i.e., computer programs tangibly embodied in an information carrier, such as in a machine-readable storage device, machine-readable storage medium, computer-readable storage device, or computer-readable storage medium, for execution or control of the operation of a data processing device (e.g., a programmable processor, computer, or multiple computers). Computer programs can be written in any form of programming language, including compiled or interpreted languages, and can be deployed in any form, including as standalone programs or modules, components, subroutines, or other units suitable for use in a computing environment. Computer programs can be deployed to execute on one or more computers at one location, or distributed across multiple locations and interconnected via communication networks.

[0061] The method steps of these techniques can be executed by one or more programmable processors that execute computer programs to perform the functions of these techniques by manipulating input data and generating output. The method steps can also be executed by special-purpose logic circuitry, and the means of the techniques can be implemented as special-purpose logic circuitry, such as FPGAs (Field-Programmable Gate Arrays) or ASICs (Application-Specific Integrated Circuits).

[0062] For example, processors suitable for executing computer programs include general-purpose and special-purpose microprocessors, as well as any one or more processors in any kind of digital computer. Typically, the processor receives instructions and data from read-only memory or random access memory, or both. The basic components of a computer are a processor for executing instructions and one or more storage devices for storing instructions and data. Typically, a computer will also include, or be operatively coupled to, one or more mass storage devices for storing data, such as magnetic disks, magneto-optical disks, or optical disks, to receive data from or transfer data to, or both. Information carriers suitable for embodying computer program instructions and data include all forms of non-volatile memory, including, for example, semiconductor memory devices such as EPROM, EEPROM, and flash memory devices; magnetic disks such as internal hard disks or removable disks; magneto-optical disks; and CD-ROM and DVD-ROM optical disks. The processor and memory may be supplemented by or incorporated into dedicated logic circuitry.

[0063] Machine-readable media may carry machine-readable instructions in the form of code, which may be executed by one or more processors of the machine. Machine-readable media may include storage media storing instructions, such as hard disks or removable disks; magneto-optical disks; and CD-ROMs and DVD-ROMs. Alternatively, machine-readable media may include transient media, such as signals, e.g., transmission signals, electrical signals, electromagnetic signals, optical signals, or acoustic signals. These instructions may control one or more processors to perform the processes and steps described herein and defined in the appended claims to set parameter values ​​for each power converter.

[0064] This document specifically illustrates and / or describes several embodiments of the invention. However, it should be understood that modifications and variations are contemplated and are within the scope of the appended claims.

Claims

1. A fuel cell power system, comprising: Multiple fuel cell stacks; Multiple power converters, each located at a different output terminal of each in the stack; Multiple current sensors, each located at the input of each of the power converters, each of the current sensors being configured to determine a current; Multiple voltage sensors, each located at the input of each power converter, each of the voltage sensors being configured to determine a voltage; And a computing device configured to: set one or more parameter values ​​for one of the power converters located at the output of one of the plurality of stacks, such that the stack preferentially provides power to the load; Determine the thermal power of the one stack and one or more other stacks, each of the thermal powers being determined based on the voltage and current determined at the input of the respective power converter; determine whether the thermal power of the one stack meets a criterion; In response to determining that the thermal power of the one stack meets the criterion, one or more parameter values ​​are set for each of the power converters located at the output of the one or more other stacks, such that the determined thermal power of each of the one or more other stacks more closely matches the determined thermal power of the one stack.

2. The fuel cell power system of claim 1, wherein the setting of the parameter values ​​of each of the power converters located at the output of the one or more other stacks is such that the output voltage of each power converter is greater than the output voltage of the other power converter.

3. The fuel cell power system of claim 2, wherein the output voltage of each power converter is greater than the output voltage of the other power converter, such that the power to the load is preferentially provided by the other one or more stacks.

4. The fuel cell power system according to any one of claims 1 to 3, wherein when the amount of power consumed by the load meets a criterion, the setting of the one or more parameter values ​​of the power converter causes the stack to preferentially provide power to the load.

5. The fuel cell power system according to any one of claims 1 to 4, wherein the outputs of the power converters are connected together such that power is supplied to the load via a parallel configuration of the power converters.

6. The fuel cell power system of claim 2, wherein the output voltage of the power converter is based on a voltage level input by a user via an interface of the fuel cell power system.

7. The fuel cell power system according to any one of claims 1 to 6, wherein the computing device is further configured to: store a previously determined thermal power of each of the stacks; and determine a health level of each of the stacks based on the stored thermal power of each stack.

8. The fuel cell power system of claim 7, wherein, based on a determined health level of said one stack being greater than a determined health level of said one or more other stacks, said one stack preferentially supplies power to the load.

9. The fuel cell power system of claim 7 or 8, wherein the computing device is further configured to: reset the one or more parameter values ​​of the one stack based on a corresponding determined health level, such that one of the one or more other stacks preferentially provides power to the load.

10. The fuel cell power system according to any one of claims 1 to 9, wherein the one or more parameter values ​​include at least one of current limiting, voltage setpoint, and on / off setting.

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