Systems and methods for providing heat control in a multi-stack fuel cell system

Abstract

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 can: set one or more parameter values of one of the power converters (20-1) located at an output of one of the plurality of stacks (10-1) such that the one stack prioritizes providing power to a load; determine a thermal power 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 a voltage and a current determined at an input of a respective power converter (20-1 to 20-n); determine whether the thermal power of the one stack (20-1) meets a criterion; and in response to determining that the thermal power of the one stack meets the criterion, set one or more parameter values of each of the power converters (20-2 to 20-n) located at an output of the one or more other stacks such that the determined thermal power of each of the one or more other stacks (10-2 to 10-n) more closely matches the determined thermal power of the one stack (10-1).

Description

TECHNICAL FIELD

[0001] The present disclosure relates generally 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

[0002] Fuel cell stacks are stacked from many single cells such that the cathode of one cell is electrically connected to the anode of an adjacent cell. In this way, exactly the same current passes through each cell. Efficient fuel cell power sources require proper temperature control and heat management to ensure reliable operation. For example, higher operating temperatures typically result in more generated water being evaporated, resulting in more waste heat, which risks damaging the fuel cell stack (e.g., the membrane dries out) and / or exacerbating performance degradation.

[0003] Even new fuel cell stacks are different in their performance based on their manufacturing tolerances and their respective ways of operating. Over time, the stacks degrade, but they do not degrade at exactly the same rate, even if the electrical load is shared equally among all stacks. The stacks degrade at different rates, which causes the weakest or worst one to have to do more and more of the work and work proportionally harder to keep up with the others. In this case, the fuel cell stack further degrades, such as in a runaway condition or a negative feedback loop, in which the fuel cell stack rapidly deteriorates, resulting in a significant reduction in the lifetime of the constituent system. Simply further cooling the weakest stack is not a viable solution because of the square relationship, i.e., doubling the airflow from a fan consumes four times the parasitic power. SUMMARY

[0004] Systems and methods for controlling heat generation of multiple fuel cell stacks are disclosed. Accordingly, one or more aspects of the present disclosure relate to methods for configuring multiple power converters such that heat is balanced. Some embodiments can: set one or more parameter values of one of the power converters located at an output of one of the multiple stacks such that the one stack preferentially provides power to a load; determine a thermal power of the one stack and one or more other stacks of the multiple stacks, each of the thermal powers being determined based on a voltage and a current determined at an input of a corresponding power converter; determine whether the thermal power of the one stack meets a criterion; and in response to determining that the thermal power of the one stack meets the criterion, set one or more parameter values of each of the power converters located at an output of the one or more other stacks such that a determined thermal power of each of the one or more other stacks more closely matches the determined thermal power of the one stack.

[0005] The method is implemented by a system that includes one or more hardware processors configured by machine-readable instructions and / or other components. The system includes one or more processors and other components or media, e.g., on which machine-readable instructions can be executed. Implementations of any of the technology described can include a method or procedure, an apparatus, a device, a machine, a system, or instructions stored on one or more computer-readable storage devices. BRIEF DESCRIPTION OF DRAWINGS

[0006] The details of particular implementations are set forth in the accompanying drawings and explanation below. Like reference numerals can refer to like elements throughout the description. Other features will be apparent from the following description, including the drawings and claims. However, the drawings are not intended to be limiting of the disclosure, and are merely used to illustrate more fully the disclosure. It should not be assumed that the present disclosure is limited by any of the details set forth in the description, the drawings, or the claims.

[0007] Figure 1 An example of a system to balance heat generated by a fuel cell stack is shown in accordance with one or more embodiments.

[0008] Figure 2 A process for balancing heat generated by a fuel cell stack is shown in accordance with one or more embodiments. DETAILED DESCRIPTION

[0009] As used in this application, the word "may" is used in a permissive sense (i.e., meaning having the potential to), rather than the mandatory sense (i.e., meaning must). The words "include", "including", and "includes" mean including, but not limited to. As used herein, the singular forms "a", "an" and "the" include plural referents unless the context clearly dictates otherwise. As used herein, the term "number" shall mean one or an integer greater than one (i.e., a plurality).

[0010] As used herein, the statement that two or more parts or components are "coupled" shall mean that the parts are joined or operate together either directly or indirectly, such as through one or more intermediate parts or components, so long as there is some linkage between the parts. As used herein, "directly coupled" means that two elements are directly in contact with each other.

[0011] Unless specifically stated otherwise, as apparent from the discussion, it is appreciated that throughout the specification discussions utilizing terms such as "processing", "computing", "calculating", "determining" or the like, refer to the action or processes of a specific apparatus, such as a special purpose computer or a similar electronic processing / computing device, in the sense of the action that should be performed.

[0012] Figure 1 A multi-stack fuel cell power system 5 is shown that includes power converters 20 configured to cause one of a set of stacks 10 to follow the heat of the one of the stacks 10 at a certain time. At this time, this stack can be designated as a master stack. Also, while an electrical load limit can be set for this stack (e.g., a limit on rate of change), this stack effectively follows the load. The remaining stacks can be controlled based on a heat setpoint to be reached, which can be derived from the heat generated by the master stack. At another subsequent time, another stack of the set can be designated and controlled as the master stack.

[0013] In some embodiments, the outputs of the power converters 20 of the system 5 are connected in a parallel configuration such that the stacks 10-1 through 10-n (n being a natural number) provide power to a load. In some embodiments, the power converters 20 are DC-DC (DC / DC) converters, which include electronic circuits or electromechanical devices that convert a direct current (DC) source from one voltage level to another. For example, each power converter 20 can be a DC / DC buck-boost converter, a linear regulator, a voltage regulator, a motor generator, a rotary converter, or a switched-mode power supply. In some embodiments, the outputs of the power converters 20 are regulated. Also, in some embodiments, the power provided to the load can be linear, switched, or battery-based.

[0014] In some embodiments, each power converter 20 has one or more analog inputs, such as a voltage setpoint and a current limit, for controlling the output power from each power converter. For example, the power control component 32 can set the voltage of each power converter 20-2 through 20-n (n being a natural number) to be higher than the voltage setpoint of the power converter 20-1, such that the power converters 20-2 through 20-n preferentially feed power to the load. In this example, the power control component 32 can configure the power converter 20-1 as the master stack by setting its current limit to be higher than the current limits of the power converters 20-2 through 20-n. When the load demand meets a criterion, and thus when a substantial amount of power is drawn from the system 5, the stack 10-1 and the power converter 20-1 can participate in supplying the excess power demand. However, because the heat estimation component 34 can determine the thermal power generated from each stack 10, the power control component 32 can increase the current limits of each power converter 20-2 through 20-n such that the power converters 20-2 through 20-n deliver more power. In some implementations, the heat estimation component 34 can determine these thermal powers periodically or aperiodically. In another implementation, the heat estimation component 34 can determine these thermal powers based on a request received from a user via the user interface 18.

[0015] In some embodiments, the power control component 32 can configure one stack 10 as the primary 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 the stack 10 as primary to supply transient loads by following the power cycle. In some embodiments, the power control component 32 alternates which of the stacks 10 is used as the primary stack. In some implementations, more than one stack can operate as the primary stack. In any of these cases, the other stacks that are not currently operating as the primary stack can increase or decrease their power generation / generation to follow the heat generation of the primary stack.

[0016] In some embodiments, the power control component 32 can configure the weakest or least healthy stack 10 as the primary stack. In these or other embodiments, the power control component 32 can configure the strongest or most healthy stack 10 as the primary stack. The primary stack will generally follow the load. For example, if the load is zero, the primary stack and all other stacks can not provide power; however, as the load increases, the power converter of the primary stack can follow the load. That is, the primary stack power can increase at the fastest speed possible to match the load. In effect, all stacks 10 in the system 5 can follow the load by correspondingly providing power, but the primary stack can lead and the other stacks can follow the primary stack. However, this can not mean that the primary stack 10 will exceed the level of equal sharing. The stacks 10 other than the primary stack 10 can follow the primary stack such that they attempt to match the thermal power (or other matching parameter) of the primary stack and follow behind. In another example, the primary stack can be in an inactive state (while all other stacks are actively sourcing power) until the demand from the load rises above a threshold.

[0017] Figure 1The electronic storage 22 includes electronic storage media that electronically stores information. The electronic storage media of the electronic storage 22 can include system storage that is integrated into the system 5 (i.e., substantially non-removable), and / or removable storage that can be removably 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 22 can be (in whole or in part) a separate component within the system 5, or the electronic storage 22 can be (in whole or in part) integrated with one or more other components of the system 5 (e.g., the user interface device 18, the processor 30, etc.). In some embodiments, the electronic storage 22 can be located in a server, in a server that is part of the external resources 24, in the user interface device 18, and / or in other locations, along with the processor 30. The electronic storage 22 can include a storage controller and one or more optically readable storage media (e.g., optical disks, etc.), magnetically readable storage media (e.g., magnetic tape, magnetic hard drive, floppy disk drive, etc.), electrically charge-based storage media (e.g., EPROM, RAM, etc.), solid-state storage media (e.g., flash drive, etc.), and / or other electronically readable storage media. The electronic storage 22 can store software algorithms, information obtained and / or determined by the processor 30, information received via the user interface device 18 and / or other external computing systems, information received from the external resources 24, and / or other information that enables the system 5 to function as described herein.

[0018] The external resources 24 can include sources of information (e.g., databases, websites, etc.), external entities that participate in the system 5, one or more servers external to the system 5, networks, electronic storage, equipment related to Wi-Fi technology, equipment related to Bluetooth technology, and / or other resources. Bluetooth) technology-related equipment, data input devices, power sources, transmission / reception 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 can be provided by other components or resources included in system 5. Processor 30, external resources 24, user interface devices 18, electronic storage 22, network 70, and / or other components of system 5 can be configured to communicate with one another by way of wired and / or wireless connections, such as a network (e.g., a local area network (LAN), the Internet, a wide area network (WAN) such as the Internet, a wireless access network (RAN), a public switched telephone network (PSTN)), cellular technology (e.g., GSM, UMTS, LTE, 5G, and the like), Wi-Fi technology, another wireless communication link (e.g., radio frequency (RF), microwave, infrared (IR), ultraviolet (UV), visible light, centimeter wave, millimeter wave, and the like), a base station, and / or other resources.

[0019] User interface device(s) 18 of system 5 can be configured to provide an interface between one or more users and system 5. User interface device 18 is configured to provide information to and / or receive information from one or more users. User interface device 18 includes a user interface and / or other components. The user interface can be and / or include a graphical user interface configured to present views and / or fields configured to receive input and / or selections regarding particular functionality of system 5, and / or to provide and / or receive other information. In some embodiments, the user interface of user interface device 18 can 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. The present disclosure also contemplates user interface device 18 including a removable storage interface. In this example, information can be loaded into user interface device 18 from removable storage (e.g., a smart card, a flash drive, a removable disk), which enables a user to customize the implementation of user interface device 18.

[0020] In some embodiments, user interface device 18 is configured to provide a user interface, processing power, databases, and / or electronic storage to system 5. Thus, user interface device 18 can include processor 30, electronic storage 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 22, external resources 24, and / or other components of system 5, but is in communication with these components via a dedicated line, bus, switch, network, or other means of communication. The communication can be wireless or wired. In some embodiments, user interface device 18 is a laptop computer, desktop computer, smart phone, tablet computer, and / or other user interface device.

[0021] Data and content can be exchanged between various components of system 5 using any of a variety of communication protocols corresponding to different media delivery platforms, over communication interfaces (e.g., hardwired, busses, etc.) and communication paths.

[0022] In some embodiments, processor 30 can belong to a user device, consumer electronics device, mobile phone, smart phone, personal data assistant, digital tablet / computing pad, wearable device (e.g., watch), personal computer, laptop computer, notebook computer, workstation, server, high performance computer (HPC), vehicle computer, gaming or entertainment system, set-top box, or any other device. Thus, processor 30 is configured to provide information processing capabilities in system 5. Processor 30 can include one or more of a microcontroller, a digital processor, an analog processor, a digital circuit, an analog circuit, a state machine, and / or other mechanisms for electronically processing information. Although processor 30 is shown in Figure 1 system 5 as a single entity, this is for illustration purposes only. In some embodiments, processor 30 can include multiple processing units. These processing units can be physically located within the same device (e.g., server), or processor 30 can represent processing functionality of a plurality of devices operating in coordination (e.g., one or more servers, user interface device 18, devices that are part of external resources 24, electronic storage 22, and / or other devices).

[0023] As Figure 1As shown, the processor 30 is configured via machine-readable instructions to execute one or more computer program components. The computer program components can 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. The processor 30 can be configured to execute components 32, 34, 36, 38, and / or 39 by software; hardware; some combination of software, hardware, and / or firmware; and / or other mechanisms for configuring processing capabilities on the processor 30.

[0024] It should be appreciated that although the components 32, 34, 36, 38, and 39 are illustrated in Figure 1 FIG. 1 as being co-located within a single processing unit, in implementations in which the processor 30 includes multiple processing units, one or more of the components 32, 34, 36, 38, and / or 39 can be located remotely from the other components. For example, in some embodiments, each of the processor components 32, 34, 36, 38, and 39 can comprise a separate and independent processor. The description of the functionality provided by the different components 32, 34, 36, 38, and / or 39 described below is for illustrative purposes, and is not intended to be limiting, as any of components 32, 34, 36, 38, and / or 39 can provide more or less functionality than is described. For example, one or more of the components 32, 34, 36, 38, and / or 39 can be eliminated, and some or all of its functionality can be provided by other components 32, 34, 36, 38, and / or 39. As another example, processor 30 can be configured to execute one or more additional components that can perform some or all of the functionality attributed below to one of the components 32, 34, 36, 38, and / or 39.

[0025] In some embodiments, the power control component 32 can determine the number of stacks 10 and the particular stacks 10 that are currently running in the system 5, such that various different combinations of stacks 10 are used to provide power to the load. For example, the power control component 32 and the heat estimation component 34 can cause a configuration of the operating power converter 20 (or configurations) to be created for feeding power to the load. In this or another example, the switches can be configured such that the load consumes power from one or more of the stacks 10-1, 10-2,... 10-n. In some embodiments, the load includes multiple loads.

[0026] In some embodiments, the power control component 32 can be configured to identify and automatically determine one or more parameter values for each power converter 20. These parameter values can include at least one of a current limit, a voltage setpoint, an on / off setting, and another suitable control signal. By controlling these parameter values, the power converters 20 can be under full power control of the power control component 32. In some embodiments, the power converters 20 can determine their own output voltage between them based on a desired input voltage received via the user interface 18 and communicated to the respective power converters 20 via voltage control signals from the power control component 32.

[0027] In some embodiments, the power control component 32 can set a maximum current limit and / or voltage setpoint for each power converter 20 in the system 5. For example, the power converter 20-1 can be set to deliver power at 48 volts (V), and one or more power converters 20-2 through 20-n can be set to deliver power at 49 volts. But this is not intended to be limiting, as each of the one or more power converters can be set individually, and thus set to different and possibly varying currents and / or voltages.

[0028] In some embodiments, the power control component 32 can configure one or more power converters 20 such that one or more stacks 10 operate as a master stack. In some implementations, the power control component 32 can receive a voltage setting for a master stack of the system 5 as input via the user interface device 18. The power control component 32 can then configure the output voltage of the power converters 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 a voltage slightly higher than the output voltage associated with the master stack. With this configuration, the other stacks will be prioritized for feeding. That is, by setting a lower setpoint than the other stacks, the master stack 10 will allow the other stacks 10 to feed first. But by setting the current limit of the power converters 20 of the master stack higher than the current limit of the power converters 20 of the other stacks, the power converters of the master stack can facilitate delivering more current to the load when there is extra load to be pulled off.

[0029] In some implementations, the power control component 32 can control the power converters 20 associated with the master stack 10 such that the master stack prioritizes providing 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, the other stacks 10 can be configured by controlling their power converters to help and take some of the load to reduce the temperature of the master stack. Thus, each stack 10 can be controlled such that it takes turns being the master stack. With this control strategy, some embodiments of the system 5 can avoid a weak stack running out. When a weak stack is in the master stack, it can heat up faster, so the other stacks can be controlled to activate earlier to assist.

[0030] In some embodiments, rather than requiring all of the stacks 10 to provide an equal proportion of the electrical load, one stack 10 can be designated as the master stack. The effect of this can be that the stacks that perform better work a little harder than the other stacks, so the performance degradation is distributed more evenly among all of the stacks. In addition, since they can generate the same amount of heat, they can need the same cooling, so they can be operated with the same cooling flow (e.g., via a gas, air, liquid, or other medium).

[0031] When a fuel cell operates, the electrolytic oxidation of hydrogen produces a voltage that drives a current to provide useful power. However, this production is not perfectly efficient, so it produces waste heat. The heat estimation component 34 can perform calculations to provide an estimate of the heat power. In some embodiments, the heat power can be the power from the reaction (i.e., the reversible electrochemical reaction that occurs in a fuel cell by the oxidation of hydrogen to produce water) that is not efficiently converted into electricity, but is converted into heat. This heat power (P 热 ) can be generated using the following equation:

[0032]

[0033] In this equation, N 电池 is the number of cells (e.g., proton exchange membrane (PEM) fuel cells) in the stack, Δ c H LHV is the heat of combustion of hydrogen (LHV) and measured in mega joules (MJ) per kilogram (kg), M H2 is the molecular mass of hydrogen and measured in grams (g) per mole, s is the number of substances used / generated in the reaction (e.g., hydrogen consumption), z is the number of electrons used in the reaction (e.g., 2), F is the Faraday constant and measured in coulombs (C) per mole, V 堆栈 is the output voltage setpoint of the stack and measured by the voltage sensor 40, and I is the current drawn from the stack and measured by the current sensor 50. Equation 1 above can be simplified by replacing the constants with the respective values to the following equation:

[0034] Pheat = (1.253169873 Ncell - Vstack) I (2)

[0035] The value 1.253169873 can be considered an ideal low heat value (LHV) voltage.

[0036] In some embodiments, the heat estimation component 34 can implement a general strategy of stack-based estimation health to implement selection of the primary stack 10. For example, the heat estimation component 34 can be configured to store a previously determined heat power for each stack 10, and determine a health level for each stack 10 based on the stored (i.e., historical) heat power for each stack. In this or another example, using the power from one or more values of the heat estimation component 34, the power control component 32 can be configured to reset a parameter value of a power converter (e.g., 20-1) associated with a primary stack (e.g., 10-1) and reset a parameter value 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) based on the respective, determined health levels, such that the other stack is prioritized to provide power to the load. The power control component 32 and the heat estimation component 34 can thus configure this change of the primary stack; as a result, the other stack can be caused to degrade at now a greater rate (e.g., by running the other stack via configuration of the respective power converter such that the other stack is hotter than it would be without the selection of the other stack to reset its parameter value(s)).

[0037] The processor 30 can load values from the electronic storage 22, the processor 30 can learn optimal values, and then store these new values to the electronic storage 22. These values can include heat power, parameter values for controlling the power converters 20, values for controlling the cooling equipment 60, values from the sensors 55, 56, 40, 41, 50, 51, and / or one or more other devices, total power-on time since power-on, total energy generated, and / or other suitable values. One or more of these values can be read from the electronic storage 22 at start-up. Once running, the processor 30 can record these values to the electronic storage 22 or another destination.

[0038] In some embodiments, the cooling control component 36 can send control signals to each of a set of fans, impellers, and / or pumps. In some embodiments, the cooling control component 36 can use the output values of the thermistors 55-56 to control the cooling equipment 60. Thus, the control of the fans can be heavily dependent on the thermal power, which is the amount of heat required for the fans to cool. For example, by using the power control component 32 and the heat estimation component 34 to match the thermal power of the main stack 10, the cooling control component 36 can use the temperature sensors 55-56 to effectively match the airflow and fan control. Since fan power is proportional to the airflow squared, the most efficient (and quiet) point can be when the airflow is matched. Each of the thermistors 55 (e.g., 55-1, 55-2,... 55-n) can be placed before the stack 10, for example, at or near the airflow duct. And each of the thermistors 56 (e.g., 56-1, 56-2,... 56-n) can be placed after the stack 10, for example, at the other end of the airflow duct. In some embodiments, the cooling equipment 60 can be coupled to the stack 10. For example, the cooling equipment 60 can include a set of fans, impellers, and / or pumps that are located at or near the stack 10, for example, at the back (or front) of the system 5. The cooling equipment 60 (e.g., 60-1, 60-2,... 60-n) can exhaust air, hydrogen, and / or water vapor. Some embodiments of the system 5 can reduce production costs by placing the stack 10 into an airflow, into a box, and / or into a hydrogen feed.

[0039] Known fuel cell stack cooling systems include a fixed maximum airflow for each stack. Thus, if a system has multiple units, each unit has the same airflow and runs at maximum power, each stack must endure the same amount of heat. Any power demand beyond this maximum can cause the stacks to run hotter, but these stacks cannot dissipate the excess heat, leaving them at greater risk of damage and shorter life. In some embodiments, the power control component 32 controls the power converters 20 so that the amount of cooling required by each stack 10 is balanced. Thus, some embodiments can have cooling equipment 60 (e.g., when using fans, by approximately the same amount of airflow) that runs evenly, which results in lower parasitic power consumption (i.e., due to the way that the non-linear terms in the control equation work) than a system that has one piece of cooling equipment running high and others running low. Thus, some embodiments of the system 5 can have the same cooling (e.g., running at the same or similar fan speeds) even at non-maximum power, because the amount of heat generated by each of the stacks 10 is the same, resulting in the lowest parasitic power consumption. Thus, some embodiments of the system 5 can balance the speed of the fans.

[0040] 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. With this combined approach, if one 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 cause such a reduction from one stack by controlling an increase in heat generation from one or more other stacks 10, thereby effectively balancing the 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 swapping one stack 10 with another stack 10 as the primary stack or as a stack powering the parasitic load. The temperature at which a hot stack 10 can sustain or operate can be directly proportional to its degradation, such that the hotter the stack, the more degradation it can experience. Some embodiments of the power control component 32 and the heat estimation component 34 can thus control and reduce degradation by dynamically balancing the heat between the stacks 10.

[0041] Some embodiments of the processor(s) 30 can include a balancing algorithm that requires power to implement. For example, during a start-up phase, the processor 30 can obtain power from the battery 16 through a closed switch. That is, upon turning on, the load and / or the processor 30 can consume power from the battery 16. For example, the system 5 can include a switch controlled by the switch control component 38 such that the processor 30 stops receiving power from the battery at the end of the power-on phase by opening the switch. That is, in this or another example, the system 5 can include a plurality of other switches controlled by the switch control component 38 such that the processor 30 starts obtaining power from one or more of the stacks 10-1, 10-2,... 10-n at the end of the power-on phase by closing the other switches. Each of these other switches can be connected between one of the diodes 45 and the processor 30. In some embodiments, the switch control component 38 can configure the other switches such that the stacks 10 share the parasitic load. In other embodiments, the switch control component 38 can configure the other switches such that one of the stacks 10 powers the parasitic load. In these other embodiments, the switch control component 38 can configure the other switches such that the stacks and power converters combine to alternate powering the parasitic load.

[0042] Some embodiments of system 5 can include switches for alternating stacks that deliver these voltage levels to cooling equipment 60. Thus, as one stack (e.g., 10-1) can be used to power such equipment, which can for example consume 200 Watts (W), the rate of degradation of this one stack can be faster than other stacks 10. In some embodiments, cooling control component 36, switch control component 38, and / or power control component 32 (i.e., via parameter settings of power converters 20) can thus shift around the source from which stacks 10 power cooling equipment 60 (e.g., another stack 10-2 can subsequently take over from stack 10-1 to power this parasitic load). It is an important aspect of the present disclosure that for system 5, each stack 10 has at least one power converter 20 to better control the power from each stack.

[0043] The number and particular stacks 10 can be controlled by processor 30. In some embodiments, power control component 32 can determine from this number and these stacks by turning on and / or off switches so that various different combinations of stacks 10 are utilized in feeding power to processor 30. In some implementations, power lines can extend from outputs of diodes 45 to processor 30 via a set of switches. In this or another example, power lines can extend from outputs of power converters 20 (or from outputs of current sensors 51) to processor 30 through switches. In some embodiments, power control component 32 determines the apportioning 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).

[0044] In some embodiments, each of a plurality of diodes (e.g., 45-1, 45-2,... 45-n) can be located at or near an input of each power converter 20.

[0045] In some embodiments, the system 5 can include a set of current sensors (e.g., 50-1, 50-2,... 50-n), each located at an input of each power converter 20, each current sensor 50 configured to determine a current passing through the respective sensor. In some embodiments, the system 5 can include another set of current detectors (e.g., 51-1, 51-2,... 51-n), each located at an output of each power converter 20, each current sensor 51 configured to determine a current passing through the respective sensor. In some embodiments, the system 5 can include a set of voltage sensors (e.g., 40-1, 40-2,... 40-n) located at or near an output of each fuel stack 10, each voltage sensor 40 configured to determine a voltage relative to its respective mounting location. In some embodiments, the system 5 can include another voltage sensor 41 located at a shared, parallel output of the power converters 20, the voltage sensor 41 configured to determine a voltage relative to its mounting location. Each of the voltage sensing devices 40-41 can be a voltmeter, an analog multimeter, a digital multimeter, or another device configured to measure voltage (i.e., electric potential) and transmit its reading to the processor 30.

[0046] In some embodiments, the power control component 32 can increase one or more of a current limit and a voltage set point of one or more power converters 20 when the heat generated by the primary stack 10 meets a criterion. In these or other embodiments, the power control component 32 can decrease one or more of a current limit and a voltage set point of one or more power converters 20 when the heat generated by the primary stack meets a criterion. In some embodiments, the thermal power of the fuel cell stack 10 can be matched by balancing the power settings (e.g., current, voltage, etc.) between the power converters 20.

[0047] In some embodiments, when multiple stacks 10 are used, some embodiments can configure some stacks 10 to preferentially feed power to the load, for example, when one (or more) other stacks 10 are not operating. For example, power control component 32 can increase power generation from one or more stacks 10-2 through 10-n. In this or another example, power control component 32 can decrease power generation from one or more stacks 10-2 through 10-n. That is, by preferentially feeding power through stacks 10-2 through 10-n and power converters 20-2 through 20-n, power fed via main stack 10-1 and power converter 20-1 can be reduced. In some implementations, power drawn using power converters 20-2 through 20-n can be adjusted so that the heat generated at each of stacks 10-2 through 10-n respectively associated with each of power converters 20-2 through 20-n is 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 can set one or more parameter values of power converters 20-2 through 20-n so that the heat of stacks 10-2 through 10-n is increased to balance or match the heat of stack 10-1. In another example, power control component 32 can set one or more parameter values of power converters 20-2 through 20-n so that the heat of stacks 10-2 through 10-n is decreased to balance or match the heat of stack 10-1.

[0048] In some embodiments, heat estimation component 34 can determine the heat each fuel cell stack 10 is delivering. When stack 10-1 is designated as the main stack, power control component 32 can draw at least a nominal amount of heat from one or more other stacks 10-2 through 10-n based on the determination of heat estimation component 34. For example, to accomplish this, power control component 32 can cause an increase in the maximum current draw limit with respect to one or more power converters 20-2 through 20-n.

[0049] In some embodiments, the heat following stacks 10 are not necessarily part of the same system as the main stack. In some implementations, there can be one or more stack systems installed adjacent to each other. In this implementation, one stack system can act as the main stack and the remaining stack system(s) can follow. This is beneficial, for example, when the cooling flow experienced by all stack systems is the same, for example, when a single cooling fan / pump controls the cooling flow to multiple stacks. In some embodiments, cooling control component 36 can implement a temperature-based control strategy via the conduits in or associated with which cooling activity occurs, by naturally balancing any differences in cooling.

[0050] In some embodiments, the control strategy can cause all of the thermal following stacks 10 to reach the same hot spot, which can equal the heat generated by the primary stack. In some implementations, this approach can not be desirable after a long period of operation. For example, the thermal following stacks 10 can experience different conditions, resulting in different levels of (e.g., reversible) temporary or permanent performance loss (e.g., due to dryout or another fault condition). In this or another example, a thermal setpoint offset or scaling for at least one of the thermal following stacks 10 can enable the stack to recover from the performance loss.

[0051] Since the primary stack is subject to higher instantaneous loads than the thermal following stacks 10, it can degrade faster or regulate better. To ensure wear / condition equalization, the power control component 32 and / or the heat estimation component 34 can periodically reallocate which stack is the primary stack. These reallocations can be based on elapsed time or according to other metrics, such as the current primary stack’s performance in a standardized test.

[0052] In some embodiments, the voltage output from each stack 10 can change depending on the current draw. For example, based on a polarization graph, the stack’s batteries can operate at 1.0 volt (V) when there is no load. And, when there is a load draw, for example, several amperes (A), the voltage of each battery of the stack 10 can be 0.65 V. For example, each stack 10 of a fuel cell can output 48 V (or 24 V or another appropriate voltage, i.e., depending on the current application) of no-load voltage.

[0053] In some embodiments, the current sensor 51 can be used to confirm that the power converter 20 is functioning properly. 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 can not be used for the disclosed thermal following approach, unless in a system where the current sensor 50 is not present. In these latter 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. Given 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.

[0054] In some embodiments, system 5 can include a software-based observer (SBO) or hardware-based observer (HBO) safety circuit (not shown). This circuit can be a processor or microcontroller that monitors signals and detects whether these signals have any safety-related faults. For example, the entire control software can not need to be certified, documented, or written to the same quality. The monitored signals can include fuel / hydrogen inlet pressure, printed circuit board (PCB) temperature, and / or differential pressure on stack 10 to indicate airflow. These can capture over-temperature, under-temperature, low airflow, overpressure, and pressure rise, among other functionality, when the valves are closed.

[0055] In some embodiments, power converter 20 can support any input voltage (e.g., ranging from 20 to 60 V, 9 to 60 V, or another suitable range). In some embodiments, power converter 20 can support any output voltage (e.g., about 48 V, about 24 V, or another suitable voltage). In some embodiments, power converter 20 can support any current draw (e.g., about 40 A or another suitable number of amperes). In some embodiments, another power converter (not shown) can support different output voltages (e.g., 5.0 V and 3.3 V) for powering intake valves, purge valves, louvers motors, various sensors disclosed herein, processor 30, and SBO circuit. In some embodiments, valve control assembly 39 can be configured to control one or more of these valves (not shown). Thus, processor 30 can be configured to control or otherwise interface with a balance of plant (BOP), which refers to all supporting components and auxiliary systems (e.g., other than stack 10 and power converter 20) needed by system 5 to deliver energy to a load.

[0056] In some embodiments, power converter 20-1 is identical to every other power converter (e.g., 20-2 to 20-n) in system 5. In these or other embodiments, power converter 20-1 is different from at least one of the other power converters 20 in the system.

[0057] In some embodiments, external resources 24 and / or user interface device 18 can 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 measurements.

[0058] Figure 2A method 100 of load balancing a plurality of fuel cells based on thermal management is shown in accordance with one or more embodiments. The method 100 can be performed by a computer system comprising one or more computer processors and / or other components. The processors are configured by machine- readable instructions to execute computer program components. The operations of method 100 given below are illustrative. In some embodiments, method 100 can be accomplished with one or more additional operations not described, and / or without one or more of the Figure 2 operations discussed. For example, one or more of the operations described can be eliminated, and / or one or more other operations can be added in various embodiments of method 100. The operations of method 100 are not necessarily performed in the order discussed.

[0059] In operation 102 of method 100, a parameter value(s) of a power converter located at an output of one stack of a plurality of fuel cell stacks can be set such that the stack preferentially provides power to a load. For example, a power control component 32 (as shown and described herein) can set a voltage level, a current limit, and / or turn on a power converter (e.g., 20-1) such that a stack (e.g., 10-1) associated with the power converter operates as a master stack. In this or another example, a power control component 32 (as shown and described herein) can set voltage levels, current limits, and / or turn on power converters (e.g., 20-2 through 20-n) to 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. Figure 1 Figure 1 In operation 104 of method 100, a thermal power of one stack of a plurality of stacks and one or more other stacks can be determined based on a voltage and a current, which can be determined at an input of a respective power converter. For example, a thermal power of stacks 10 can be determined using Equation 1 or Equation 2 (as described above). In this example, each stack 10 can have a power converter 20 at an output thereof. In some embodiments, operation 104 is performed by a processor component that is the same as or similar to thermal estimation component 34 (as shown and described herein).

[0060] In operation 106 of method 100, a thermal power of one or more stacks of a plurality of stacks can be determined based on a voltage and a current, which can be determined at an input of a respective power converter. For example, a thermal power of stacks 10 can be determined using Equation 1 or Equation 2 (as described above). In this example, each stack 10 can have a power converter 20 at an output thereof. In some embodiments, operation 106 is performed by a processor component that is the same as or similar to thermal estimation component 34 (as shown and described herein). Figure 1

[0061] ​​In operation 106 of the method 100, it can be determined whether the thermal power of the stack meets one or more criteria. For example, the thermal power of the stack 10-1 can be compared to 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 heat estimation component 34, as shown and described herein. Figure 1

[0062] In operation 108 of the method 100, the parameter value(s) of each power converter located at the output of one or more other stacks can be set so that the determined thermal power of each of the one or more other stacks more closely matches the determined thermal power of the stack. For example, the power control component 32, as shown and described herein, can set the voltage level and current limit for each other power converter (e.g., 20-2 through 20-n) so that the associated stack (e.g., 10-2 through 10-n) follows the heat generation of the primary stack. In some embodiments, operation 108 is performed by another processor component that is the same as or similar to the power control component 32. Figure 1

[0063] The techniques described herein can be implemented in digital electronic circuitry, or in computer hardware, firmware, software, or in combinations of them. These techniques can be implemented as a computer program product, i.e., a computer program tangibly embodied in an information carrier, e.g., in a machine-readable storage device, a machine-readable storage medium, a computer-readable storage device, or a computer-readable storage medium, for execution by, or to control the operation of, data processing apparatus, e.g., a programmable processor, a computer, or multiple computers. A computer program can be written in any form of programming language, including compiled or interpreted languages, and can be deployed in any form, including as a stand-alone program or as a module, component, subroutine, or other unit suitable for use in a computing environment. A computer program can be deployed to be executed on one computer or on multiple computers at one site or distributed across multiple sites and

[0064] Method steps of the techniques can be performed by one or more programmable processors executing a computer program to perform functions of the techniques by operating on input data and generating output. Method steps also can be performed by, and an apparatus of the techniques can be implemented as, special purpose logic circuitry, e.g., an FPGA (field programmable gate array) or an ASIC (application-specific integrated circuit).

[0065] ​​Processors suitable for the execution of a computer program include, by way of example, both general and special purpose microprocessors, and any one or more processors of any kind of digital computer. Generally, a processor will receive instructions and data from a read-only memory or a random access memory or both. The essential elements of a computer are a processor for performing instructions and one or more memory devices for storing instructions and data. Generally, a computer will also include, or be operatively coupled to receive data from or transfer data to, or both, one or more mass storage devices for storing data, such as magnetic, magneto-optical, or optical disks. Information carriers suitable for embodying computer program instructions and data include all forms of non-volatile memory, including by way of 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 disks. The processor and the memory can be supplemented by, or incorporated in, special purpose logic circuitry.

[0066] A machine-readable medium can carry code that can be machine-executed for causing a machine to perform various operations. The machine-readable medium can include a storage medium having stored thereon instructions that can be executed by one or more processors of a machine. The machine-readable medium can include a storage medium including one or more of: a hard disk; a floppy disk; a magnetic tape; a compact disk; a DVD; a Blu-ray disk; a memory; and a storage circuit (e.g., a cache). The machine-readable medium can also include a transient medium, such as a transitory signal, a propagating signal, an electromagnetic signal, an optical signal, and the like. The transient medium can be a signal directly measurable as a physical quantity during transmission. Examples of a physical quantity include: one or more of: electric, electromagnetic, magnetic, radio frequency (RF), infrared, acoustic, and optical. The instructions can be executable by one or more processors of a machine to cause the machine to perform operations described herein and defined by the appended claims.

[0067] A number of embodiments of the application have been specifically illustrated and / or described herein. However, it will be appreciated that modifications and variations of the illustrative embodiments are contemplated and covered by the following claims.

Claims

1. A fuel cell power system, comprising: Multiple fuel cell stacks; Multiple power converters, each located at the output of a different one of the multiple fuel cell stacks; 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 terminal of each of the power converters, each of the voltage sensors being configured to determine a voltage; as well as The computing device is configured as follows: Set one or more parameter values ​​for one of the power converters located at the output of one of the plurality of fuel cell stacks, such that the fuel cell stack preferentially provides power to the load; The thermal power of one fuel cell stack and another thermal power of one or more other fuel cell stacks are determined, each of the thermal power and the other thermal power being determined based on the voltage and the current determined at the input terminal of the respective power converter; Determine whether the thermal power of a stack meets a thermal threshold amount; as well as In response to determining that the thermal power of the one fuel cell stack meets a thermal threshold, one or more parameter values ​​are set for each of the power converters located at the output of the one or more other fuel cell stacks, such that another determined thermal power of each of the one or more other fuel cell stacks matches the determined thermal power of the one fuel cell 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 fuel cell 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 power converter, such that the power to the load is preferentially provided by the one or more other fuel cell stacks.

4. The fuel cell power system of claim 1, wherein when the amount of power consumed by the load meets a power threshold, the setting of the one or more parameter values ​​of the power converter causes the fuel cell 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 claim 1, wherein the computing device is further configured to: Store the previously determined thermal power of each of the plurality of fuel cell stacks; and The health level of each of the plurality of fuel cell stacks is determined based on the stored thermal power of each of the plurality of fuel cell stacks.

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

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

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

11. The fuel cell power system of claim 1, wherein each of the thermal power and the other thermal power is further determined based on the number of cells in the respective fuel cell stack.

12. The fuel cell power system according to claim 1, further comprising: A battery configured to power the computing device when the plurality of fuel cell stacks and power converters are energized.

13. The fuel cell power system according to claim 12, further comprising: Multiple diodes, each diode located at the input terminal of each of the power converters; A switch, wherein the computing device is further configured to control the switch such that the computing device stops receiving power from the battery when the power-on ends; as well as Multiple other switches, each connected between one of the diodes and the computing device, wherein the computing device is further configured to control the other switches such that the computing device begins to receive power from one or more of the multiple fuel cell stacks.

14. The fuel cell power system according to claim 13, wherein the power converter is a buck-boost converter.

15. The fuel cell power system according to claim 1, further comprising: Multiple fans, each located near a different one of the multiple fuel cell stacks; as well as Multiple temperature sensors are located at the input and output of each of the plurality of fuel cell stacks, and correspond to the airflow through each of the plurality of fuel cell stacks. The computing device is further configured to determine the speed of each of the fans based on temperature readings from the temperature sensor. The fan speed is the same when the determined thermal power of each of the one or more other fuel cell stacks matches the determined thermal power of the one fuel cell stack.

16. A machine-readable medium carrying machine-readable code, which, when executed by at least one processor of a machine, causes the machine to perform a method, said method being used in conjunction with a plurality of fuel cell stacks, a plurality of power converters, a plurality of current sensors, and a plurality of voltage sensors, each power converter being located at the output of a different one of each in the stack, each current sensor being located at the input of each of the power converters, each of the current sensors being configured to determine a current, and each voltage sensor being located at the input of each of the power converters, each of the voltage sensors being configured to determine a voltage; said method comprising: 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 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 stack meets the criteria; as well as 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.

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