Energy storage circuit with bypass functionality for high-voltage DC energy management system

Abstract

To improve electrical safety in high voltage DC systems.SOLUTION: An energy storage module 18 includes: a positive electrode terminal 26 and a negative electrode terminal 28; an energy storage assembly 30 configured to store electrical energy, the energy storage assembly including an energy storage cell 32 and a sensor 35; a switching assembly that is switchable into either of an operational state and a bypass state and optionally a cross-conduction state, and that, in the operational state, electrically connects the energy storage assembly to the positive and negative electrode terminals to supply them with electrical power, in the cross-conduction state, short-circuits the energy storage assembly, and in the bypass state, allows a direct electrical connection between the positive and negative electrode terminals; and an energy storage local control unit that, upon detecting a fault condition of the energy storage assembly based on the sensor, causes, preferably initiates, the switching assembly to progress from the operational state through the cross-conduction state into the bypass state.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an energy storage circuit. The present invention further relates to an energy storage module, an energy management system, and related methods. [Background technology]

[0002] Energy storage modules based on supercapacitors are increasingly in demand for a variety of applications that require high peak power for short periods of time, such as powering electric starter motors in large engines instead of using conventional lead-acid batteries.

[0003] Another promising application is grid stabilization in data centers, especially for AI applications. AI systems typically experience power surges due to sudden, large computational demands during inference, which quickly subside once completed. Supercapacitors are easily rechargeable and can provide large peak power for short periods of time, making supercapacitor-based energy storage modules well-suited to mitigating the effects of such surges.

[0004] The energy storage cells described here can be divided into three categories: batteries, capacitors, and supercapacitors (sometimes called ultracapacitors).

[0005] As used herein, the term "battery" refers to an energy storage cell that stores electrical energy solely through electrochemical redox reactions. This typically includes primary batteries, which can only be discharged. However, as used herein, the term "battery" refers exclusively to secondary batteries, i.e., batteries that can be charged and discharged.

[0006] As used herein, the term "capacitor" refers to an energy storage cell that stores electrical energy electrostatically.

[0007] The term "supercapacitor" as used here refers to a special type of capacitor, which can be further distinguished into double-layer capacitors (DLCs), which store energy electrostatically using a Helmholtz double layer; pseudocapacitors, which store electrical energy electrochemically by faradaic electron charge transfer such as intercalation or electroadsorption; or hybrid capacitors, which use both DLC and pseudocapacitor mechanisms.

[0008] Various methods have been developed to detect cells that behave abnormally and solutions to mitigate this behavior. The following approaches are referenced:

[0009] Unpublished German patent application 102024102852.1 discloses a method for detecting and balancing abnormal cells, the disclosure of which is incorporated herein by reference.

[0010] Patent Document 1 discloses a battery management circuit that senses the individual voltages of each battery cell to detect a faulty cell, and prevents the faulty cell from affecting the battery's output voltage.

[0011] US Pat. Nos. 5,999,249, 5,999,252, 5,999,262, and 6,099,272 disclose means for identifying abnormal cells based on leakage current.

[0012] Patent Document 5 discloses a control unit that can detect an abnormal cell in a battery module and control cell balance adjustment.

[0013] Patent Document 6 discloses a method for identifying and selectively disconnecting a faulty battery cell in a battery pack of multiple battery cells.

[0014] Patent Document 7 discloses a method for identifying a failed cell based on the amount of cell balancing required.

[0015] Patent Document 8 discloses a device that passes a current through a failed cell to activate a sacrificial component and disconnect the failed cell.

[0016] US Pat. No. 5,649,399 discloses a method for performing a balancing operation based on a voltage difference.

[0017] US Pat. No. 5,699,499 discloses a method for balancing based on Coulomb threshold levels.

[0018] US Pat. No. 5,699,499 discloses a device for locating and electrically isolating a faulty cell in a network of cells in a battery.

[0019] US Pat. No. 5,649,493 discloses a battery cell protection system that isolates failed cells.

[0020] Patent Document 13 discloses a method for inspecting a secondary battery in an offline mode.

[0021] Isolating supercapacitor modules with common faults such as overcharge, overdischarge, and imbalance is a critical task during abnormal conditions, especially for high-voltage DC applications, where interrupting high-voltage DC current can be difficult due to the nature of the current.

[0022] Bypassing, for example in the case of supercapacitors, is a feature that can redirect current from a failed energy storage cell to another circuit permanently or in the case of abnormal voltage. Conventional techniques used to bypass a supercapacitor cell or module from the actual circuit are typically done by connecting resistors, diodes, reverse diodes, or other transistors to the supercapacitor cell / module to be bypassed. These techniques are generally time-consuming, increasing the risk of damage occurring in a short time frame, such as a fraction of a second. Typically, these techniques take more than a few seconds, e.g., 10 seconds, to bypass a supercapacitor. [Prior art documents] [Patent documents]

[0023] [Patent Document 1] US Patent Application Publication No. 2015 / 0044527A1 [Patent Document 2] U.S. Patent No. 11133133B2 [Patent Document 3] U.S. Patent No. 10649040B2 [Patent Document 4] U.S. Patent No. 11124087B2 [Patent Document 5] European Patent Application Publication No. 3800762A1 [Patent Document 6] U.S. Patent No. 7,683,575 B2 [Patent Document 7] U.S. Patent No. 9097774B2 [Patent Document 8] U.S. Patent No. 9,866,043 B2 [Patent Document 9] U.S. Patent Application Publication No. 2021 / 0281084A1 [Patent Document 10] U.S. Patent No. 8,796,993 B2 [Patent Document 11] US Patent Application Publication No. 5,227,259A [Patent Document 12] US Patent Application Publication No. 5,894,212A [Patent Document 13] U.S. Patent No. 10,317,477 B2 Summary of the Invention [Problem to be solved by the invention]

[0024] While this concept of bypassing failed electronic components is commonly known, there is still a need for faster and safer bypass techniques in the field.

[0025] The object of the present invention is to improve the electrical safety of high voltage DC systems. This object is achieved by the subject matter of the independent claims. Preferred embodiments are the subject matter of the dependent claims. [Means for solving the problem]

[0026] The present invention provides an energy storage circuit comprising: positive and negative terminals configured to connect to an external device; an energy storage assembly configured to store electrical energy, the energy storage assembly having at least one energy storage cell and at least one sensor; a switching assembly switchable between an operating state and a bypass state and optionally to a cross-conduction state; and an energy storage local control unit configured to: in the operating state, the switching assembly electrically connects the energy storage assembly to the positive and negative terminals to supply power; in the bypass state, the switching assembly allows a direct electrical connection between the positive and negative terminals; and in the cross-conduction state, the switching assembly short-circuits the energy storage assembly and / or connects the energy storage assembly to a bypass connection connecting the positive and negative terminals; detect a fault condition of the energy storage assembly based on the at least one sensor; and transition, preferably activate, the switching assembly upon detecting the fault condition.

[0027] Preferably, at least one energy storage cell comprises a supercapacitor. Preferably, at least half of the energy storage cells are supercapacitors. Preferably, each energy storage cell is a supercapacitor.

[0028] The proposed invention relates to isolating a faulty energy storage cell, e.g., a supercapacitor circuit or entire module, from an energy storage rack or electrical system current. Fault conditions can be detected using well-known methods. Generally, a fault condition is determined to exist when the system's electrical parameters meet certain conditions. In the event of a fault condition, such as overcharge, deep discharge, severe imbalance, emergency, maintenance, repair, or efficiency or performance improvement, the circuit must be bypassed within milliseconds to prevent potential damage, particularly to the supercapacitor and other components. This can reduce or avoid accelerated wear, material damage, excessive overheating, electrolyte leakage, chemical contamination, and the risk of fire.

[0029] For example, a gradual switchover from an operational state to a cross-conduction state to a bypass state allows for rapid isolation of a failed energy storage cell without interrupting the energy storage function, followed by a complete electrical bypass that avoids further involvement of the failed energy storage cell.

[0030] Preferably, the switching assembly includes a normally open closure switch configured to close in response to an activation signal, wherein in the operating state the closure switch is open and in the cross conduction and bypass states the closure switch is closed to form an electrical connection between the positive and negative terminals that bypasses the energy storage assembly. Preferably, the closure switch includes or consists of a closure pyroswitch.

[0031] In the operating state, the bypass path is interrupted. In the cross-conduction state, the closing switch briefly allows short-circuiting of the energy storage assembly and / or conduction to the bypass connection. In the cross-conduction state, a path is created for the high-voltage system current, potentially mitigating or preventing current interruption when the opening switch is opened. The pyroswitch ensures safe and fast switching after start-up. Additionally, the pyroswitch typically does not reverse in an accident, protecting the user and system from further fault conditions and injury.

[0032] Preferably, the switching assembly includes an opening switch that is normally closed and configured to open in response to an activation signal, wherein in the operating and discharging states the opening switch is closed and in the bypass state the opening switch is open. Preferably, the opening switch includes or consists of an opening pyroswitch or a fuse (e.g., a DC power fuse).

[0033] In the operating state, the opening switch connects the energy storage assembly to the terminals, allowing electrical energy to be charged to or discharged from the supercapacitor. In the cross-conduction state, the opening switch allows a short circuit and / or connection between the terminals for a short time, thereby preventing an interruption of the HV current. In the bypass state, the opening switch prevents power from being supplied to the energy storage assembly. In the case of a fuse, if a short circuit occurs during the cross-conduction state, the fuse will interrupt the current.

[0034] Preferably, the closing and opening switches are combined into a single component or assembly, allowing for easy replacement and maintenance as the entire switching sequence can be performed by one element.

[0035] Preferably, the switching assembly includes a surge protection device arranged to absorb voltage peaks caused by the switching assembly going into a bypass state. Preferably, the surge protection device is electrically coupled in parallel with the opening switch. The surge protection device is capable of withstanding a shock that interrupts current flow (if any) from or to the energy storage assembly. This is particularly useful during a cross-conduction condition, even if it is short-lived.

[0036] Preferably, the switching assembly is continuously operable in a discharge state, where the energy storage assembly is continuously discharged when no charging current is applied. Preferably, the switching assembly includes at least one discharge resistor arranged to continuously discharge the energy storage assembly or at least one energy storage cell, the discharge resistor being dimensioned to provide a discharge time of at least one day, preferably up to seven days, for discharging the energy storage assembly or each energy storage cell. This configuration facilitates balancing of the module, as the discharge resistor operates regardless of the bypass function. Furthermore, after entering the bypass state, the supercapacitor discharges without any additional action and is safe enough not to require special cooling.

[0037] Preferably, the switching assembly can be further switched to a discharge state after the bypass state, in which the energy storage assembly is discharged. Preferably, the switching assembly includes a discharge switch that, in a closed state, enables the energy storage assembly to be discharged via the discharge resistor, the discharge switch being operatively coupled to the energy storage local control unit and being switched between a closed state and an open state in which the energy storage assembly is prevented from being discharged via the discharge resistor. Typically, when in the bypass state, the energy storage cells may still contain electrical energy depending on their previous state. This remainder can be safely removed by a common discharge circuit with a resistor. Thus, not only can the supercapacitor be quickly shut down, but also the supercapacitor can be placed in a safe state for diagnostics and / or maintenance, etc.

[0038] Preferably, the discharge resistor is dimensioned so that the discharge time for discharging the energy storage assembly exceeds 30 minutes, preferably 1 hour. A properly dimensioned discharge resistor results in a small and inexpensive component. Active cooling can be avoided, and general cooling by available air is sufficient to release the remaining energy from the supercapacitor. This advantage comes at the expense of discharge time. This allows for a combination of fast bypass times (e.g., around 1 millisecond) and safe, problem-free discharge times (e.g., 30 minutes to 1 hour).

[0039] The present invention provides an energy storage module for an energy storage management system, the energy storage module comprising an energy storage circuit and an energy cell management system configured to monitor and control an energy storage assembly.

[0040] The present invention provides a method of operating an energy storage circuit or module, the method comprising:

[0041] a) measuring, with at least one sensor, at least one electrical parameter of the energy storage assembly and / or at least one energy storage cell; b) evaluating the electrical parameters using the energy storage local control unit to detect a fault condition that causes the switching assembly to progress from an operating state, through any cross conduction state, to a bypass state.

[0042] Preferably, the energy storing local control unit simply triggers the switching assembly to progress through the different states, which progression is carried out by the switching assembly.

[0043] Preferably, the energy storage local control unit closes the closure switch to initiate the cross conduction state, and the bypass state is obtained after the closure switch is closed and forms an electrical connection between the positive and negative terminals that bypasses the energy storage assembly.

[0044] Preferably, the energy storing local control unit activates the firing pellet of the closing pyroswitch.

[0045] Preferably, the energy storage local control unit actuates an opening switch to open and transition to a bypass state.

[0046] Preferably, the current surge caused by the closure of the closing switch activates the opening switch to open and transition to a bypass state.

[0047] Preferably, a surge protection device absorbs voltage peaks caused by the opening of the opening switch.

[0048] Preferably, when the energy storage module is in the bypass state, the energy storage local control unit closes the discharge switch to discharge the energy storage assembly through the discharge resistor.

[0049] The present invention provides an energy management system configured for grid stabilization and / or peak power supply, comprising a plurality of energy storage modules electrically connected to each other and a system control unit operably coupled to each energy storage local control unit.

[0050] Preferably, each energy storage local control unit is configured to report a fault condition or a bypass condition to the system control unit upon detecting a fault condition or determining that the respective energy storage module is in a bypass state, and the system control unit, upon receiving the report, recalculates at least one electrical parameter of the energy management system, such as available electrical energy, available power, available current, and / or available voltage.

[0051] The present invention provides a method of operating an energy management system, the method including each energy storage local control unit reporting a fault condition or determining that a respective energy storage module is in a bypass state to a system control unit, the system control unit receiving the report and recalculating at least one electrical parameter of the energy management system.

[0052] Further features, effects, or advantages of the present invention will be described in more detail below, with the understanding that not all elements need to be present at the same time or in the same quantity.

[0053] In some embodiments, it is contemplated to bypass a supercapacitor circuit without discharging the circuit. In some embodiments, the bypassing of the supercapacitor circuit is accomplished by a pyroswitch or pyrofuse. In some embodiments, this bypassing technique is applicable to supercapacitor modules connected in both series and parallel options. In some embodiments, this technique does not require a complete discharge of the circuit that needs to be bypassed. Therefore, a discharge resistor is not necessarily required. In some embodiments, the proposed bypassing technique is relatively faster than existing solutions, as it can be completed in a time range approaching 1 millisecond. In some embodiments, the bypassing prevents excessive heat generation within the system, since it does not require discharging the supercapacitor circuit.

[0054] In the event of an electrical fault, the failed supercapacitor module can be bypassed within 1 millisecond without discharging, avoiding voltage and / or current imbalances within the supercapacitor energy storage system. This is significantly faster than existing solutions, which typically take at least 1 minute to discharge the supercapacitor module as a first step, generating a large amount of heat, and then isolate the module as a second step.

[0055] In some embodiments, the bypass circuit includes a combination of two pyroswitches to isolate the supercapacitor modules. In some embodiments, whenever an abnormal condition occurs, both switches operate quickly to bypass the failed or unbalanced supercapacitor module. In some embodiments, one of the switches first shorts the positive and negative connections of the supercapacitor module, and then, with a minimal delay, the other switch disconnects the supercapacitor module from the positive connection. Thus, both the capacitor circuit and the respective switch are unloaded or bypassed from the entire supercapacitor energy storage system.

[0056] In some embodiments, the local control unit detects an abnormal condition, such as high or low voltage, and immediately activates a bypass for the target supercapacitor module. In some embodiments, the local control unit reports to the system-level control unit that the target supercapacitor module has been bypassed. In some embodiments, the system-level control unit accordingly recalculates the availability and available performance values ​​(power, current, energy, voltage) of the capacitor circuits throughout the energy storage system to continue using the capacitor circuits within specifications.

[0057] The main advantages realized by the idea presented here are that bypassing can be performed within milliseconds and that the technique can be applied to series or a combination of series and parallel connections of supercapacitor cells or modules.

[0058] In some embodiments, a specialized transfer switch is actuated by a pyropil, providing very fast actuation over mechanical switches actuated by, for example, a solenoid. In some embodiments, two electrically synchronized switches are used that are independently activated (actuated) by a pyropil.

[0059] In some embodiments, a bypass can be provided for a capacitor circuit in which capacitors are connected in series or in series / parallel.

[0060] In some embodiments, the bypass is performed without significantly discharging the target capacitor circuit. In some embodiments, the local control unit detects a failure (or a high risk of capacitor failure) in a low-voltage capacitor circuit and activates a bypass for that target capacitor circuit. In some embodiments, one switch shorts the positive and negative connections of the capacitor circuit, and with a minimal delay, another switch disconnects the capacitor circuit from the positive connection, thus unloading both the capacitor circuit and the respective switch.

[0061] In some embodiments, a special pyrotechnic low voltage switch can be used to bypass the capacitor circuit in less than 1 millisecond.

[0062] In some embodiments, an additional discharge circuit comprising a discharge resistor and a discharge switch allows a bypassed module to be discharged when the module is disconnected from the system. In some embodiments, the discharge switch is closed after a particular circuit is bypassed, so that the additional power loss from the resistive discharge is not a factor for the system.

[0063] Optionally, the discharge resistors can be sized appropriately for very slow discharge (on the order of a few days) and the switch can be removed from the circuit, improving electrical safety. This also improves control and assembly. It also improves voltage balancing of the module, even when balancing is done by electronics using permanently connected resistors.

[0064] In some embodiments, one pyroswitch can be converted into a DC power fuse, where a short circuit of the other switch activates the fuse, simplifying control, especially since high currents automatically activate the fuse.

[0065] In some embodiments, a surge protection device (SPD) can be used to absorb voltage peaks caused by interrupting the current.

[0066] In some embodiments, the local control unit reports to the system level that the capacitor circuit has been bypassed, and in some embodiments, the system level recalculates the availability of the capacitor circuit in the overall energy storage, and then recalculates the available performance values ​​(power, current, energy, voltage) to continue using the capacitor circuit within specifications.

[0067] In some embodiments, a discharge resistor can be added. The discharge current is very low and the resistor size can be small. After bypassing, there is time to slowly discharge the failed capacitor circuit.

[0068] Embodiments of the present invention will now be described in more detail with reference to the accompanying schematic drawings listed below. [Brief explanation of the drawings]

[0069] [Figure 1] FIG. 1 shows an embodiment of an energy management system. [Figure 2] FIG. 2 shows a first embodiment of an energy storage module. [Figure 3] FIG. 3 shows a second embodiment of the energy storage module. [Figure 4] FIG. 4 shows a third embodiment of the energy storage module. [Figure 5] FIG. 5 shows a fourth embodiment of the energy storage module. [Figure 6] FIG. 6 shows a fifth embodiment of the energy storage module. [Figure 7] Figure 7 shows the functional principle of the integrated pyroswitch. [Figure 8] Figure 8 shows the functioning principle of the integrated pyroswitch. [Figure 9] Figure 9 shows the functioning principle of the integrated pyroswitch. [Figure 10] Figure 10 shows the functioning principle of an independent pyroswitch. DETAILED DESCRIPTION OF THE INVENTION

[0070] 1, an energy management system 10 includes a grid supply line 12 that supplies power to an electrical load 14. The energy management system 10 is preferably configured for and used in an E-STATCOM application.

[0071] The electrical load 14 has periods requiring peak power and periods when power demand is relatively low and stable. An example of such an electrical load 14 is an AI data center. To provide a fast response, the energy management system 10 connects the energy storage module 18 to the grid supply line 12. However, the electrical load 14 may have different load characteristics.

[0072] The energy management system 10 includes a power converter 16 configured to convert AC current to DC current and vice versa. The power converter 16 is connected to the grid supply lines 12 and to the electrical loads 14.

[0073] The energy management system 10 preferably includes multiple energy storage modules 18 arranged in racks 20. The racks 20 may be connected in parallel and / or series, as the case may be. That is, some racks 20 may be connected in series as groups, and other racks 20 may be connected in parallel as groups. These groups may be connected in series and / or parallel to achieve desired electrical parameters, such as system voltage and available peak power, among others. The energy storage modules 18 are connected to the power converters 16 to receive and supply power.

[0074] The energy management system 10 includes a system control unit 22 communicatively coupled to each energy storage module 18, and specifically to its energy storage local control unit 24.

[0075] Alternatively, if the energy management system 10 is connected to a grid supply line 12 that is a high voltage DC line, the power converter 16 may be a DC-DC converter or may be omitted.

[0076] Referring to FIG. 2, a first embodiment of the energy storage module 18 will be described.

[0077] Energy storage module 18 includes a positive terminal 26 and a negative terminal 28. Terminals 26, 28 allow electrical connection to other components, particularly other energy storage modules 18. Energy storage modules 18 can be selectively connected in series or parallel.

[0078] The energy storage module 18 includes an energy storage assembly 30. The energy storage assembly 30 includes a plurality of energy storage cells 32 in the form of supercapacitors. The energy storage cells 32 are connected according to the intended application, and their configuration varies depending on the module voltage and available peak power required for the application.

[0079] The energy storage assembly 30 further comprises at least one sensor 35 configured to measure an electrical parameter, such as cell voltage, of the energy storage assembly 30. Other types of sensors are possible and can be used.

[0080] The energy storage module 18 includes a switching assembly 36. The switching assembly 36 includes an opening switch 38 in the form of a pyroswitch. The switching assembly 36 includes a closing switch 40 in the form of a pyroswitch.

[0081] The opening switch 38 is electrically connected to one of the terminals 26, 28, for example, the positive terminal 26, and the energy storage assembly 30. The other of the terminals 28, 26, for example, the negative terminal 28, is permanently connected to the energy storage assembly 30.

[0082] The closing switch 40 is electrically connected to the same terminals 26, 28 (here, the positive terminal 26) as the opening switch 38. The closing switch 40 is electrically connected to the same terminals 28, 26 (here, the negative terminal 28) as the energy storage assembly 30.

[0083] The energy storage local control unit 24 is operatively coupled to sensors 35 to receive data indicative of electrical parameters. The energy storage local control unit 24 is operatively coupled to a switching assembly 36. The energy storage local control unit 24 is typically implemented at the rack level. The energy storage local control unit 24 may also be a distributed system. In other words, the energy storage local control unit 24 may be formed by multiple physical devices, and the devices may be distributed across multiple components, such as energy storage modules 18 and racks 20.

[0084] Next, the operation of the energy management system 10 will be described in more detail.

[0085] Initially, the energy storage module 18 is in an operational state. In this state, the open switch 38 electrically connects the positive terminal 26 to the energy storage assembly 30. The close switch 40 is open, interrupting the bypass connection 42 from the positive terminal 26 to the negative terminal 28.

[0086] The energy storage local control unit 24 constantly monitors the energy storage assembly 30 using sensors 35. If a fault occurs in the energy storage assembly 30 for any reason, the energy storage local control unit 24 detects the fault and initiates a switching process that advances the switching assembly 36 from an operational state through a cross-conduction state to a bypass state. After initiation, the switching process proceeds without further intervention from the energy storage local control unit 24. In other words, the energy storage local control unit 24 can only initiate the switching process; it cannot control its progression, which is impeded by the associated components. The switching process lasts approximately 1 millisecond.

[0087] Shortly after the initiation of the switching process, the switching assembly 36 enters a cross-conduction state. The cross-conduction state is an intermediate state that lasts for less than the entire switching process. The cross-conduction state prevents an open circuit that would interrupt the HV system current, thereby preventing the formation of an arc.

[0088] In a cross-conduction state, the closing switch 40 is closed, connecting the positive terminal 26 to the negative terminal 28 via the bypass connection 42, while the opening switch 38 is still closed. Thus, a short circuit is formed in the energy storage assembly 30, causing a surge and a strong but brief discharge of the energy storage cells 32. The duration of the cross-conduction state is so short that no significant damage is caused to the energy storage cells 32 or other components, while also avoiding an interruption of the HV current.

[0089] The switching process then advances the switching assembly 36 to a bypass state. In the bypass state, the opening switch 38 is open, interrupting the electrical connection from the positive terminal 26 to the energy storage assembly 30. System current now flows from the positive terminal 26 to the negative terminal 28 through the bypass connection 42, thereby isolating the failed energy storage assembly 30 from the system circuit.

[0090] The energy storage local control unit 24 sends a message to the system control unit 22 that each energy storage module 30 is now in a bypass state and is not participating in the system.

[0091] Upon receiving this message, the system control unit 22 recalculates the electrical parameters of the energy management system 10 excluding the failed energy storage module 30, specifically the available electrical energy, available power, available current, and / or available voltage.

[0092] Referring to FIG. 3, a second embodiment of the energy storage module 18 will be described only insofar as it differs from the first embodiment.

[0093] Energy storage module 18, and more particularly switching assembly 36, further includes a discharge switch 44 and a discharge resistor 46. Discharge switch 44 is positioned to enable discharge of energy storage assembly 30 via discharge resistor 46. Discharge switch 44 is operatively coupled to energy storage local control unit 24.

[0094] When in the bypass state, the energy storage local control unit 24 closes the discharge switch 44 to discharge the energy storage assembly 30 for approximately 30 minutes to 1 hour. The discharge resistor 46 is sized accordingly.

[0095] In a variant (not shown), the discharge switch 44 is omitted and a discharge resistor 46 is connected in parallel with the energy storage assembly 30 or the energy storage cell 32 to allow permanent discharge. The discharge resistor 46 is sized so that discharging takes at least one day, and preferably several days.

[0096] With reference to FIG. 4, a third embodiment of the energy storage module 18 will be described, focusing only on the differences from the second embodiment.

[0097] The energy storage module 18 includes a surge protection device (SPD) 48. The SPD 48 is connected in parallel with the opening switch 38. The SPD 48 absorbs surges that occur during transitions to the discharge and bypass states, i.e., when the current in the local energy storage circuit is interrupted.

[0098] In a variant (not shown), an SPD 48 is installed and the discharge switch and resistors 44, 46 are omitted.

[0099] With reference to FIG. 5, a fourth embodiment of the energy storage module 18 will be described, focusing only on the differences from the first embodiment.

[0100] The opening switch 138 is configured in the form of a DC power fuse, and the SPD 48 is connected in parallel with the opening switch 138 .

[0101] Upon detecting a fault condition, the energy storage local control unit 24 initiates a switching process by actuating the closing switch 40. In a cross-conduction state, the closing switch 40 is closed, the current caused by the short circuit exceeds the threshold of the DC power fuse, and the short circuit current opens the closing switch 138. The surge generated when the opening switch 138 opens is again absorbed by the SPD 48. It is possible to omit the SPD 48, but this is not usually recommended.

[0102] 6, a fifth embodiment of an energy storage module 18 will be described, focusing only on the differences from the fourth embodiment. The energy storage module 18 includes a discharge switch and resistors 44, 46, as described in the second embodiment. As with the second embodiment, it is also possible to omit the discharge switch 44 and dimension the discharge resistor 46 accordingly.

[0103] 7 to 9, the functional principle of the pyroswitch 50 will be described in more detail, specifically a variant in which the opening switch 38 and the closing switch 40 are integrated into a single component. The pyroswitch 50 includes an electrical ignition device 52 and a pyropill 54. The pyropill 54 is a small amount of explosive material. Furthermore, the pyroswitch 50 includes a plurality of static contacts 56 and a moving contact 58. The static contacts 56 are organized in two sets.

[0104] 7 shows the pyroswitch 50 in an activated state, with the movable contact 58 in the starting position and electrically connecting the first pair of static contacts 56. That is, the opening switch 38 is closed and the closing switch 40 is open.

[0105] FIG. 8 shows how, upon receiving an electrical signal, the electrical ignition device 52 ignites the pyropil 54. The expanding hot gases generated by the pyropil 54 push the moving contact 58 into contact with all of the static contacts 56. This corresponds to a cross-conduction state in which both the open and closed switches 38, 40 are closed. As shown, the duration of the cross-conduction state can be adjusted by changing the size of the static contacts 56 and moving contacts 58 and the distance between the static contacts 56. In an alternative configuration, the static and moving contacts 56, 58 can be configured to avoid cross-conduction, thereby adding a small delay.

[0106] 9 shows the movable contact 58 in its final position, electrically connecting the second pair of static contacts 56. This opens the opening switch 38 and closes the closing switch 40.

[0107] 10 shows an alternative configuration in which the open switch 38 and the close switch 40 are separate components. Both switches 38, 40 are operatively coupled to the energy storage local control unit 24. Again, an electrical ignition device 52 is used. In this configuration, the energy storage local control unit 24 generates electrical ignition pulses that activate (actuate) the switches 38, 40. The time delay between the ignition pulses can be adjusted by the energy storage local control unit 24 or by the length of the electrical connection from the energy storage local control unit 24 to the electrical ignition device 52. In this configuration, it is also possible to activate the switches 38, 40 synchronously. In this case, there may be no cross-conduction. [Explanation of symbols]

[0108] 10 Energy Management System 12 Grid Supply Lines 14 Electrical Load 16 Power Converter 18 Energy Storage Module 20 racks 22 System Control Unit 24 Energy Storage Local Control Unit 26 Positive terminal 28 Negative terminal 30 Energy Storage Assembly 32 Energy storage cells 35 sensors 36 Switching Assembly 38 Open switch 40 Closure switch 42 Bypass Connection 44 Discharge switch 46 Discharge resistor 48 Surge Protection Devices (SPDs) 50 Pyro Switch 52 Electric ignition device 54 Pyropill 56 static contacts 58 Movable contact 138 Open switch

Claims

1. An energy storage circuit for an energy storage module (18), comprising: - a positive terminal (26) and a negative terminal (28); an energy storage assembly (30) configured to store electrical energy, said energy storage assembly (30) comprising at least one energy storage cell and at least one sensor (35); a switching assembly (36) switchable between an operating state and a bypass state, and optionally a cross-conduction state and / or a discharge state, wherein in the operating state, the switching assembly (36) electrically connects the energy storage assembly (30) to the positive and negative terminals to supply power, and in the bypass state, the switching assembly (36) allows a direct electrical connection between the positive and negative terminals (26, 28), and in the cross-conduction state, the switching assembly (36) shorts out the energy storage assembly (30) and / or connects the energy storage assembly (30) to a bypass connection (42) connecting the positive and negative terminals (26, 28); an energy storage local control unit (24) configured to detect a fault condition of the energy storage assembly (30) based on said at least one sensor (35), and configured to cause, preferably trigger, the switching assembly (36) to progress from said operating state, through said cross conduction state, to said bypass state upon detection of said fault condition.

2. 2. The energy storage circuit of claim 1, wherein the switching assembly (36) comprises a closure switch (40) that is normally open and configured to close in response to an activation signal, wherein in an operating state the closure switch (40) is open and in a cross conduction state and a bypass state the closure switch (40) is closed, forming an electrical connection between the positive terminal (26) and the negative terminal (28) that bypasses the energy storage assembly (30).

3. The energy storage circuit of claim 2 , wherein the closure switch (40) comprises or consists of a closure pyroswitch (50).

4. 4. The energy storage circuit of claim 1, wherein the switching assembly (36) comprises an opening switch (38, 138) that is normally closed and configured to open in response to an activation signal, wherein in the operating state and the discharging state, the opening switch (38, 138) is closed, and in the bypass state, the opening switch (38, 138) is open.

5. The energy storage circuit of claim 4, wherein the opening switch (38, 138) comprises or consists of an opening pyroswitch (50) or a fuse, such as a DC power fuse.

6. An energy storage circuit according to any one of claims 2 to 5, wherein the closing switch (40) and the opening switch (38) are combined into a single component.

7. 7. The energy storage circuit of claim 1, wherein the switching assembly includes a surge protection device arranged to absorb voltage peaks caused by the switching assembly transitioning to the bypass state.

8. The energy storage circuit of claim 7, wherein the surge protection device (48) is electrically coupled in parallel with the opening switch (38, 138).

9. 9. The energy storage circuit of claim 1, wherein the switching assembly (36) comprises at least one discharge resistor (46) arranged to continuously discharge the energy storage assembly (30) or the at least one energy storage cell, the discharge resistor (46) being dimensioned such that a discharge time for discharging the energy storage assembly (30) or each energy storage cell is at least one day, preferably at most seven days.

10. 9. The energy storage circuit of claim 1, wherein the switching assembly includes a discharge switch that, in a closed state, enables discharging of the energy storage assembly via a discharge resistor, the discharge switch being operatively coupled to the energy storage local control unit and being switched between a closed state and an open state to prevent discharging of the energy storage assembly via the discharge resistor, and wherein the discharge resistor is preferably sized such that a discharge time for discharging the energy storage assembly exceeds 30 minutes, preferably exceeds 1 hour.

11. An energy storage module (18) for an energy storage management system, comprising: The energy storage module (18) comprises an energy storage circuit according to any one of claims 1 to 10 and an energy cell management system configured to monitor and control the energy storage assembly (30).

12. A method of operating an energy storage circuit according to any one of claims 1 to 10 or an energy storage module (18) according to claim 11, comprising: a) measuring at least one electrical parameter of the energy storage assembly (30) and / or at least one energy storage cell using at least one sensor (35); b) evaluating the electrical parameters using an energy storage local control unit (24) and, upon detecting a fault condition, progressing the switching assembly (36) from the operating state through any of the cross conduction states to the bypass state.

13. 13. The method of claim 12, wherein the energy storing local control unit (24) simply triggers the switching assembly (36) to progress through different states, and the progression is performed by the switching assembly (36).

14. An energy management system (10) configured for grid stabilization and / or peak power supply, comprising:

12. An energy management system (10) comprising: a plurality of energy storage modules (18) according to claim 11 electrically connected to one another; and a system control unit (22) operably coupled to each energy storage local control unit (24).

15. 15. The system of claim 14, wherein each energy storage local control unit (24) is configured to report the respective energy storage module (18) to the system control unit (22) upon detecting the fault condition or determining that the respective energy storage module (18) is in the bypass state, and the system control unit (22) is configured to recalculate at least one electrical parameter of the energy management system (10), such as available electrical energy, available power, available current, and / or available voltage, upon receiving the report, and wherein each energy storage local control unit (24) is configured to report the respective energy storage module (18) to the system control unit (22) upon detecting the fault condition or determining that the respective energy storage module (18) is in the bypass state, and the system control unit (22) is configured to recalculate at least one electrical parameter of the energy management system (10) upon receiving the report.

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