Modular DC-DC converter equipment, operating methods and electrolysis devices

Abstract

A modular DC-DC converter device (100) includes input interfaces (102a, 102b), output interfaces (104a, 104b), a plurality of N DC-DC converter sub-modules (108, 110, 112, 114, 116, 118) connected in ISOP configuration, each sub-module (108, 110, 112, 114, 116, 118) capable of providing substantially the same amount of sub-module DC power, and a device controller unit 120 configured to individually enable and disable the supply of sub-module DC power to the sub-modules (108, 110, 112, 114, 116, 118), wherein the DC-DC converter device (100) is configured to provide the required operating DC power to a DC load (122) connected to the output interfaces (104a, 104b) and requiring an operating DC power not exceeding (N-1) times the sub-module DC power, the DC load (122) being an electrolytic capacitor. The system comprises N submodules (108, 110, 112, 114, 116, 118), each including one or more bypass switches (108a, 108b, 108c) controlled by a device controller unit (120), wherein the device controller unit (120) is configured to use the one or more bypass switches (108a, 108b, 108c) of at least one of the N submodules to disable the DC power supply of a submodule of at least one of the N submodules (108, 110, 112, 114, 116, 118), and to periodically change which submodule of at least one of the submodules (108, 110, 112, 114, 116, 118) has its DC power supply disabled, and wherein the device controller unit (120) is also configured to distribute activation time among all submodules in the plurality of N submodules according to the aging status of each individual submodule.

Description

Technical Field

[0001] This disclosure generally relates to the operation of modular, electrically isolated or non-isolated DC-DC converter devices, such as converter devices for connecting high-power electrical devices requiring direct current (DC) to a DC network. More specifically, this disclosure relates to a modular DC-DC converter device, an electrolysis apparatus, and a method of operating a modular DC-DC converter device. Furthermore, this disclosure also relates to a computer program product and a computer-readable storage medium. Background Technology

[0002] Operating an electrolysis unit, which produces hydrogen using electrolysis (the process of splitting water into hydrogen and oxygen using electrical energy), requires direct current (DC). To produce green hydrogen, the electricity is supplied by renewable energy sources such as wind turbines (or wind farms containing multiple turbines) or photovoltaic systems. However, distributing electricity from power suppliers to high-power devices may require high- or medium-voltage distribution networks, while high-power DC loads, such as multiple electrolysis systems in a large electrolysis unit, require large currents at relatively low voltages. Therefore, DC loads are connected to the grid via suitable power converter equipment, especially since the required DC power is often supplied by islanded grids and grids primarily fed by renewable energy sources, which are typically weak grids. For powering high-power DC loads such as large electrolysis units in weak grids, the limitation of rectifier technology stems from the grid's finite short-circuit ratio (SCR). One possible mitigation is the application of suitable power electronic (PE) switches, such as insulated-gate bipolar transistors (IGBTs) or integrated gate commutated thyristors (IGCTs), which are capable of handling the low short-circuit ratio of the connected grid.

[0003] However, on the other hand, IGBTs, in particular, may be prone to potential failures, such as latch-up, time-related dielectric breakdown, bond wire cracking, or bond wire detachment. These failure mechanisms are attributable to a single IGBT and may cause failure or malfunction of the specific equipment using that IGBT (e.g., an entire converter device or a specific submodule of a modular converter device).

[0004] CN114094834A proposes a switched-capacitor-connected DC transformer as a DC-DC converter, in which dual active full-bridge submodules, each with internal capacitors, are connected in a series input and parallel output configuration. Redundant submodules are provided, and to allow for easy replacement of faulty submodules at any time, all submodules are switched on according to a rotation scheme to keep the internal capacitors always energized. Summary of the Invention

[0005] One object of the present invention is to provide a cost-effective solution for reliably supplying DC current to high-power DC loads such as electrolysis units over long periods of time via an operable converter device optimized for long life and trouble-free operation.

[0006] This objective is achieved by a modular DC-DC converter device as described in technical solution 1, an electrolysis device as described in technical solution 6, a method for operating a modular DC-DC converter device as described in technical solution 7, a computer program product as described in technical solution 9, and a computer-readable storage medium as described in technical solution 10. Advantageous additional embodiments of the invention are disclosed in the corresponding dependent solutions.

[0007] According to a first aspect of the invention, technical solution 1 describes a modular DC-DC converter device. It includes an input interface, an output interface, a plurality of N DC-DC converter submodules connected in an ISOP (input series, output parallel) configuration, each submodule capable of providing substantially the same amount of submodule DC power, and a device controller unit configured to individually enable and disable the supply of submodule DC power to these submodules. The DC-DC converter device is configured to supply the required operating DC power to a DC load (which is an electrolytic system) connected to the output interface and whose required operating DC power does not exceed (N-1) times the submodule DC power, while the supply of submodule DC power to at least one of these submodules is disabled by the device controller unit. N is an integer greater than 1. The operating DC power may refer to the rated power of the DC load. Depending on the connected DC load, the operating DC power may be in the range of kW or MW.

[0008] The input interface is used to connect a DC-DC converter to receive DC power from a DC power source via a DC link or other DC power grid. The term "DC-DC converter submodule" refers to DC-DC converter submodules that are themselves complete DC-DC converters and are submodules of a DC-DC converter device. In other words, a modular DC-DC converter device comprises multiple submodules—multiple interconnected functional DC-DC converters—that collectively provide the DC power required for the operation of the connected DC load. Each submodule is capable of providing substantially the same amount of submodule DC power; that is, if enabled by the device controller unit, all submodules can provide at most substantially the same, i.e., very similar, amount of DC power.

[0009] To achieve the power levels required to supply DC power, such as exceeding 1 megawatt (MW) or 10 MW, to high-power DC loads (e.g., electrolytic systems, each comprising at least one row of electrolytic cells constituting a large electrolytic unit), DC-DC converter devices are provided as multiple N interconnected DC-DC converter submodules. The interconnection of these submodules follows an input-series-output-parallel (ISOP) configuration, i.e., series connection of submodules on the primary (input) side of the DC-DC converter device and parallel connection on the secondary (output) side. Through this connection, electrolytic units requiring high load currents at relatively low voltages can be powered by DC links with higher distribution voltages and thus lower primary-side currents. For example, a DC-DC converter device can be designed to provide 10, 20, or 30 MW of operating DC power to a connected electrolytic system via multiple submodules, each submodule providing, for example, approximately 1 MW (or, for example, up to 2.5 MW or more) of submodule DC power.

[0010] The number of DC-DC converter submodules required is calculated based on the total operating power requirements of the connected DC load (e.g., the connected electrolytic system) and the power transfer capability or submodule DC power of each DC-DC converter submodule.

[0011] For nonlinear DC loads such as electrolytic systems, an upper limit is defined for the required operating DC power, as the DC power demand may vary over time. However, depending on parameters such as those of the power electronic equipment used, short-term peaks of higher operating power demand may be acceptable.

[0012] The described DC-DC converter device is designed to allow a DC load for which the required operating DC power does not exceed (N-1) times the DC power of a submodule. In other words, the DC-DC converter device includes at least one more DC-DC converter submodule than the number likely required to provide its operating DC power to the DC load, so that during normal operation, at least one of the N available submodules can be disabled by the device controller unit. This N-1 design enhances the reliability of the entire modular DC-DC converter device because a redundant DC-DC converter submodule is included to ensure full-load operation, i.e., operation at 100%, even if one DC-DC converter submodule fails. In this case, the device controller unit can disable the failed DC converter submodule, for example, until it is replaced or repaired. This significantly improves the availability of DC loads such as electrolysis systems or entire electrolysis units, thereby significantly reducing opportunity costs. For electrolysis units, this significantly impacts the operating expenditure costs of the unit, as hydrogen production is not interrupted by a single point of failure. This design exhibits at least the advantages described when having one or more redundant submodules. Therefore, in the exemplary embodiment, a redundant DC-DC converter submodule is provided, thereby saving the cost of an additional submodule.

[0013] In the DC-DC converter device according to the present invention, each submodule includes one or more bypass switches controlled by a device controller unit. The device controller unit activates and deactivates the bypass switches to enable and disable the corresponding complete submodule. Other possibilities for enabling and disabling the DC power supply of the submodule may include, for example, control signals for replacing the rectifier of the DC-DC converter submodule. However, enabling and disabling the complete submodule, rather than blocking power flow within the DC-DC converter submodule, avoids or reduces unnecessary power losses within the submodule.

[0014] In the DC-DC converter device according to the present invention, the device controller unit is configured to periodically change which of at least one of a plurality of submodules has its DC power supply disabled. In other words, instead of disabling one or more selected submodules at once and keeping the remaining submodules continuously enabled, the device controller unit periodically changes which submodules are enabled to provide the required DC power. For example, periodic switching may include a rotation scheme in which each submodule is subsequently disabled for a certain period of time and then re-enabled, while another submodule is disabled instead. This distributes overall wear between semiconductor components in a high-power DC-DC converter device, reduces stress on individual components, and can significantly extend the lifespan of individual semiconductor components.

[0015] The device controller unit is configured to allocate activation time among all submodules across multiple submodules based on the aging status of each individual submodule. Using this rotation scheme based on the actual aging status of the DC-DC converter submodules, modules with lower aging levels operate for longer periods than modules with higher aging levels.

[0016] As an alternative example, the device controller unit will be configured to distribute activation time equally among all submodules across multiple submodules. In other words, each submodule will be disabled and activated according to a rotation scheme with equal time intervals, which tends to uniformly distribute the overall wear on the semiconductor components of the DC-DC converter device by balancing the on-time of each DC-DC converter submodule.

[0017] In one embodiment, the switching rate is tuned according to a specific DC-DC converter device, wherein the duration of activation or the on-time interval can range from milliseconds to days.

[0018] By employing an operating strategy of rotating activated DC-DC converter submodules, the overall wear of a DC-DC converter device comprising N DC-DC converter submodules configured with ISOP can be reduced, and the lifespan of individual semiconductors can be significantly extended. This is because the strategy reduces stress on individual components, for example, by 1 / N over equal time intervals, and this stress can be distributed among the N submodules. Furthermore, overall efficiency is improved because the submodules operate at lower temperatures.

[0019] In one embodiment, the DC-DC converter device is configured to provide the required operating DC power to a DC load with the maximum number of submodules, each providing its maximum submodule DC power, and, if necessary, also with one submodule providing power less than its maximum submodule DC power. The objective of this operating scheme is to maximize the number of DC-DC converter submodules operating at their maximum operating point. Therefore, for full-load operation (where the DC load requires 100% operating DC power, e.g., a connected electrolytic system operating at 100% load), N-1 modules operate at their maximum operating point (100% submodule operating point), while the Nth submodule is shut down.

[0020] For operation at points between no-load and near-full load, a first number of DC-DC converter submodules (excluding the remaining second number (at least two)) operate at the maximum operating point (100% submodule operating point), and one of the remaining second number of DC-DC converter submodules operates at a possible varying operating point below its maximum operating point, and is used to balance transient load fluctuations across the full range of the contribution capability of said submodule (i.e., its maximum submodule DC power). For example, if the DC-DC converter submodules consist of N = 6 submodules (5 submodules plus 1 redundant submodule), each submodule accounts for 20% of the operating DC power requirement of the connected DC load. For operating points between 80% and 100% load, 4 submodules operate at the 100% operating point, and a 5th (N-1)th submodule is used to balance load fluctuations between 80% and 100%. For operating points between 60% and 80%, the 4th (N-2) submodule is responsible for balancing load fluctuations, and submodules N-3 to N-5 operate at 100% operating points.

[0021] Even in this partial load operation, preferably, the device controller unit is configured to distribute activation time among all submodules of the plurality of submodules, and deactivation assignments (as N and N-1, N-2, ... submodules) are rotated among the plurality of DC-DC converter submodules in the ISOP configuration. This is advantageous because unnecessary cycling and the resulting stress on the semiconductors used (such as IGBTs) can be avoided, and the lifespan of the individual semiconductors can be extended. Furthermore, the rotation of deactivation assignments as N, N-1, N-2, ... submodules allows the DC-DC converter submodules to age uniformly, thereby extending the operational life of the entire DC-DC converter device in the ISOP configuration.

[0022] DC loads, such as electrolysis systems, are not directly switched on to begin operation at their operating point. Instead, in a preferred embodiment, they are enabled using a power-up sequence. However, even during the power-up (and power-down) phases, the preferred operating scheme includes operating as many DC-DC converter submodules as possible at their maximum operating points. For the power-up of the electrolysis system (0% to the set load point, i.e., the operating point), the power-up sequence begins with one submodule and increases from 0% to 100% of the operating point. Once the maximum operating point of the first submodule is reached, the second submodule increases from 0% to 100% of the operating point. This sequence is repeated in the subsequent submodules until the set load point of the electrolysis unit is reached. For the power-down of the electrolysis unit, the same method is used in reverse, wherein all but one submodule remain at their maximum operating point, and said submodule decreases to 0% before the next submodule begins its power-down process. In one embodiment, this operating strategy is controlled by a device controller unit, and the operating points of the submodules can be controlled by the device controller unit or a dedicated separate submodule controller unit, while the operating points of the DC loads can be provided to the device controller unit by the control unit of the electrolysis system or other connected DC loads.

[0023] In one embodiment, the DC-DC converter device is configured to supply a power boost required to a DC load connected to the output interface that requires a short-term power boost exceeding the operating DC power by enabling the supply of submodule DC power from at least one submodule currently disabled by the device controller unit. This operating DC power is no more than (N-1) times the submodule DC power. In this power boost mode, power and load fluctuations within the nominal operating limits of the connected DC load (e.g., an electrolytic system) are balanced by the allocated individual DC-DC converter submodules. In this power boost mode, the nominal power, i.e., the operating DC power of the connected DC load, is equal to the power rating of the combined N-1 modules, i.e., (N-1) times the submodule DC power, but the additional power boost can be provided by the Nth submodule. This submodule can draw additional power within the (short-term) limits of the connected DC load and can provide auxiliary grid services, such as frequency stabilization.

[0024] In one embodiment of a DC-DC converter device, the submodule is an electrically isolated DC-DC converter submodule, preferably a bidirectional electrically isolated DC-DC converter submodule, meaning that the electrical isolation operates in both directions. Electrical isolation prevents both DC and unwanted AC currents between two parts of an electrical system, while still allowing power transfer between these parts, for example, through capacitors or inductors, but without a conductive path. Typical variations of such electrically isolated DC-DC converters are, for example, single-active-bridge or dual-active-bridge converters. An electrically isolated DC-DC converter effectively isolates DC-based network units (e.g., DC loads, such as electrolytic systems) and DC power supplies from each other and from any upper-level common coupling point to the AC power grid. Thus, the DC-based network units are protected from adverse effects received through the DC link without causing harmful effects on the DC link and the connected units. For example, an electrically isolated DC-DC converter device allows nonlinear DC loads, such as electrolytic systems, to be decoupled from the upper-level AC power grid and from the DC link connecting the DC-DC converter device to the input interface of the DC-DC converter device (to which the DC-based network unit is connected). This significantly improves power quality at the common coupling point to the AC grid because, for example, harmonics generated by the switching of power converters used in the electrolysis system are not distributed back to the DC link and the coupling point to the AC grid. Electrical isolation also prevents circulating currents between parallel electrolysis systems, which could otherwise lead to additional losses and increase corrosion and aging on the process side (i.e., the electrolytic cell banks of the electrolysis system), and significantly improves the safety of the electrolysis unit in the event of a failure.

[0025] In one embodiment, the electrically isolated DC-DC converter submodule includes a DC-to-AC converter module connected to a transformer module, which in turn is connected to an AC-to-DC converter module. This modular design allows the operating voltage and current to be independently and individually adjusted to suit the specifications of the connected DC load and the DC link connected to the input interface of the DC-DC converter device.

[0026] According to a second aspect of the invention, an electrolysis apparatus includes one or more electrolysis systems, each electrolysis system including at least one row of electrolytic cells, wherein the electrolysis apparatus includes one or more DC-DC converter devices according to a first aspect of the invention, configured to connect the one or more electrolysis systems to receive electrical power from a DC link. In this way, the advantages and features of the modular DC-DC converter device according to the invention, having multiple DC-DC converter submodules configured in (N-1)ISOP, are also realized within the framework of an electrolysis apparatus including multiple electrolysis systems connected to a DC link via such modular DC-DC converter devices.

[0027] The DC link can be, for example, a medium-voltage DC (MVDC) link. Medium voltage (MV) is a DC voltage range between 1.5 kV and 45 kV. High-power MVDC links operate, for example, at 1.5 kV or higher. By operating at a higher voltage level instead of using a low-voltage DC link, the operating current can be reduced, thereby reducing distribution losses. Therefore, any necessary cooling can be reduced, and overall efficiency is improved. MVDC links enable cost-optimized high-power DC current distribution, and are therefore particularly suitable, for example, for powering multi-megawatt electrolysis units using DC current supplied by DC power sources (e.g., renewable energy systems such as wind farms or photovoltaic systems) or by DC current supplied by AC-DC converters that receive AC power from the AC grid through an intermediate transformer.

[0028] Using bidirectional electrically isolated DC-DC converter devices to connect to the MVDC link ensures that the MVDC link voltage will not be unavailable in the connected electrolytic system due to faults. Therefore, for example, it is not necessary to apply MVDC circuit breakers with sufficient ratings in the connected electrolytic system. Furthermore, this method allows the operating voltage of the MVDC link to remain within a cost-optimized range, independent of the operating voltage of the connected electrolytic system.

[0029] According to a third aspect of the invention, a method for operating a modular DC-DC converter device is provided, wherein the DC-DC converter device includes an input interface, an output interface, a plurality of N DC-DC converter submodules connected in an ISOP configuration, and a device controller unit, each submodule including one or more bypass switches and capable of providing substantially the same amount of submodule DC power. The provided method includes at least the steps of: individually enabling and disabling the supply of submodule DC power to the submodules by the device controller unit using the one or more bypass switches; and supplying the required operating DC power by the DC-DC converter device to a DC load connected to the output interface that requires no more than (N-1) times the operating DC power of the submodules, the DC load being an electrolytic system, wherein the supply of submodule DC power to at least one of the submodules is disabled by the device controller unit.

[0030] The steps of individually enabling and disabling the DC power supply of a submodule involve periodically changing which submodule(s)' DC power supply is deactivated. For example, periodic replacement may include a rotation scheme where each submodule is subsequently disabled for a certain period and then re-enabled, while another submodule is disabled. This distributes overall wear and tear among the semiconductor components of a high-power DC-DC converter device, reduces stress on individual components, and can significantly extend the lifespan of individual semiconductor components.

[0031] The process of periodically disabling the DC power supply of one or more submodules involves allocating activation time based on the aging condition of each individual submodule. Using this rotation scheme based on the actual aging condition of the DC-DC converter submodules, modules with lower aging conditions operate for longer periods than those with higher aging conditions.

[0032] In an alternative example, the step of periodically disabling the DC power supply of one or more of these submodules involves evenly distributing the activation time across all submodules. In other words, each submodule is disabled and activated according to a rotating scheme with uniform time intervals, which coordinates the overall wear and tear of the semiconductor components of the DC-DC converter device by balancing the on-time of the individual DC-DC converter submodules.

[0033] In one embodiment of the method, the step of individually enabling and disabling the DC power supply of a submodule includes: receiving the operating DC power value of the connected DC load; determining a maximum number of submodules for providing the maximum sum of DC power of the submodules that is less than or equal to the operating DC power value of the connected DC load; and if the sum is equal to the operating DC power value, enabling the maximum number of submodules to supply the DC power of the submodules; or if the maximum number is less than N-1 and the sum is less than the operating DC power value, enabling the maximum number of submodules to supply the DC power of the submodules and additionally enabling one submodule to provide power less than its maximum DC power; or if the maximum number is equal to N-1 and the sum is less than the operating DC power value, enabling the maximum number of submodules to supply the DC power of the submodules and additionally enabling one submodule for short-term power boost.

[0034] In this embodiment, the operating DC power required by the DC load is provided by the maximum number of submodules providing their maximum submodule DC power, plus (if necessary) a submodule providing less than their maximum submodule DC power. Alternatively, in a first mode, if the maximum submodule DC power of N-1 submodules corresponds to the operating DC power required by the connected DC load, then the N-1 submodules are enabled to provide their maximum submodule DC power. Alternatively, in a second mode, if the maximum submodule DC power of N-1 submodules is greater than the operating DC power required by the connected DC load, then at most N-2 submodules are enabled to provide their maximum submodule DC power, and another submodule providing less than its maximum submodule DC power is enabled. Alternatively, in a third mode, if the maximum submodule DC power of N-1 submodules corresponds to less than the currently required operating DC power of the connected DC load (this corresponds to a short-term exception, since otherwise the DC-DC converter device should be able to provide the power consumption of the DC load through N-1 submodules), then the N-1 submodules are enabled to provide their maximum submodule DC power, and further, the Nth submodule is not disabled but used to provide the required short-term power boost.

[0035] These operating modes apply not only to the normal operating phase of a DC load (e.g., an electrolytic system or other nonlinear DC load) but also to the power ramp-up and power ramp-down phases. That is, even during the power ramp-up and power ramp-down phases, the operating scheme involves operating as many DC-DC converter submodules as possible at their maximum operating points. For the power ramp-up of an electrolytic system, the power ramp-up sequence starts with one submodule, ramping up from 0% to 100% operating point. Once the maximum operating point of the first module is reached, the second module ramps up from 0% to 100% operating point. This sequence is repeated in the subsequent submodules until the set load point of the DC load is reached, i.e., until the DC load receives its required operating DC power. For the power ramp-down of a DC load, the same method is used in reverse, where all modules except one remain at their maximum operating points, and the power ramp-down of the next submodule only begins after one submodule has reached 0% operating point.

[0036] According to a fourth aspect of the invention, a computer program product includes code portions that, when executed on a device controller unit of a DC-DC converter device according to a first aspect of the invention, enable the DC-DC converter device to perform the steps of the method according to a third aspect of the invention. For this purpose, in one embodiment of the DC-DC converter device, the device controller unit includes a programmable device and a memory. The programmable device refers to any data processing unit, such as a central processing unit (CPU), microprocessor, microcontroller, or any other processor. The memory may include a computer program product corresponding to a computer program adapted to configure the programmable device of the device controller unit to perform the steps of the method according to a third aspect of the invention.

[0037] Furthermore, according to a fifth aspect of the invention, a computer-readable storage medium is provided, which stores a computer program product according to a fourth aspect of the invention. And according to a sixth aspect of the invention, a data carrier signal is provided, which carries the computer program product according to the fourth aspect of the invention. The computer program product can be provided on a computer-readable storage medium, i.e., a data carrier, such as a CD, DVD, memory card, or other storage medium, particularly a non-volatile storage medium, which stores data that can be loaded into the memory of a device controller unit, wherein the data represents the computer program. As another example, the data carrier can also be a data connection, such as a telephone cable or data cable or a wireless connection, and the computer program product can be represented as a data carrier signal transmitted via the data carrier.

[0038] Although not explicitly described, the given embodiments can be used in any combination or sub-combination. Attached Figure Description

[0039] The features, characteristics, and advantages of the present invention described above, as well as the ways in which they are implemented, will become clearer and easier to understand in conjunction with the following description of exemplary embodiments, which are described in more detail with reference to the accompanying drawings.

[0040] Figure 1 A first example of a modular DC-DC converter device according to an embodiment of the present invention is illustrated schematically; Figure 2 A second example of a modular DC-DC converter device according to another embodiment of the present invention is illustrated schematically; Figure 3 An example of an electrolysis apparatus according to yet another embodiment of the present invention is illustrated, which is connected to a medium-voltage direct current (MVDC) link; and Figure 4 An example of a method for operating a modular DC-DC converter device according to yet another embodiment of the present invention is illustrated. Detailed Implementation

[0041] It should be understood that other embodiments may be used, and structural or logical modifications may be made without departing from the scope of the invention. It should be understood that, unless specifically stated otherwise, features of the various exemplary embodiments described above and below may be combined with each other. Therefore, this description should not be interpreted in a restrictive sense, and the scope of the invention is defined by the appended claims.

[0042] exist Figure 1 The diagram schematically illustrates a first example of a modular DC-DC converter device according to an embodiment of the present invention. The illustrated modular DC-DC converter device 100 includes input interfaces 102a, 102b, output interfaces 104a, 104b, and a plurality of DC-DC converter sub-modules 106 (N sub-modules 108, 110, 112, 114, 116, 118), which are connected in an input series, output parallel (ISOP) configuration. N is a positive integer. Figure 1 In this context, N equals 6. Each of the submodules 108, 110, 112, 114, 116, and 118 with N=6 can provide substantially the same amount of submodule DC power. The DC-DC converter device 100 also includes a device controller unit 120 configured (e.g., programmed) to individually enable and disable the supply of submodule DC power to submodules 108, 110, 112, 114, 116, and 118, such that when the device controller unit 120 disables the supply of DC power to at least one of the submodules 108, 110, 112, 114, 116, and 118, the DC-DC converter device 100 can supply DC power to the DC load 122 (in... Figure 1 The system supplies the operating DC power required by the DC load 122 to the electrolysis system connected to the output interfaces 104a and 104b.

[0043] DC-DC converter device 100 is configured or selected such that the total DC power provided by N-1 submodules 108, 110, 112, 114, 116 at the same time is suitable for the connected DC load 122, that is, the operating DC power of the DC load is generally no more than (N-1) times the DC power of the submodules.

[0044] exist Figure 1In the illustrated embodiment, submodules 108, 110, 112, 114, 116, and 118 each include bypass switches 108a, 108b, 108c; 110a, 110b, 110c; 112a, 112b, 112c; 114a, 114b, 114c; 116a, 116b, 116c; and 118a, 118b, 118c. The device controller unit 120 is configured or programmed to individually enable and disable the DC power supply to submodules 108, 110, 112, 114, 116, and 118 by controlling the on and off states of the bypass switches, thereby enabling or disabling the bypass of the respective submodule under ISOP configuration.

[0045] exist Figure 1 In the illustrated embodiment, the device controller unit includes at least a programmable device 124 and a memory 126. The programmable device 124 refers to any data processing unit, such as a central processing unit (CPU), microprocessor, microcontroller, or any other processor. The memory 124 may include a computer program product corresponding to a computer program adapted to configure the programmable device 124 of the device controller unit 120 to perform steps of a method for operating a modular DC-DC converter device 100, including periodically changing which of the submodules 108, 110, 112, 114, 116, 118 is disabled in its DC power supply; in other words, which of the N submodules is bypassed by setting a corresponding bypass switch. Furthermore, the device controller unit 120 is configured to perform a rotation scheme, i.e., sequentially bypassing (at least) one of these submodules, each submodule being bypassed at different times, while the remaining submodules supply their DC power to the DC load 122 connected to the output interfaces 104a, 104b. In other words, the device controller unit 120 is configured to allocate activation time among all the multiple sub-modules 106 (sub-modules 108, 110, 112, 114, 116, 118), for example, depending on the aging status of each individual sub-module.

[0046] Due to its ISOP configuration, the DC-DC converter device 100 is suitable for providing DC current to electrolytic systems. The ISOP configuration is particularly suitable for connecting DC loads with high DC current requirements (e.g., several thousand amperes (kA), such as 10 kA) and relatively low voltage values ​​to DC networks or DC links configured to provide medium or high voltage at relatively low current values, such as medium-voltage DC (MVDC) links. For example, an MVDC link provides a DC voltage between 1 kV and 45 kV, such as 20 kV.

[0047] Device controller unit 120 is configured to enable as few submodules as possible to provide the required operating DC power by having as many submodules as possible provide their maximum submodule DC power. This enables DC-DC converter device 100 to meet the operating DC power required by DC load 122 by having the maximum number of submodules 108, 110, 112, 114, 116 provide their respective maximum submodule DC power, and if necessary, any remaining difference is provided by a submodule 118 at a power lower than its maximum submodule DC power.

[0048] This applies even when the power required by DC load 122 exceeds the actual maximum operating DC power, at least for a short period, because DC-DC converter device 100 is also configured to provide the required power boost to DC load 122 connected to output interfaces 104a, 104b and requiring a short-term power boost exceeding (N-1) times the operating DC power of the submodule, by enabling the supply of submodule DC power to a submodule currently disabled by device controller unit 120. That is, the device controller unit suspends the sequential enabling and disabling of submodules and temporarily enables an additional currently disabled Nth submodule.

[0049] exist Figure 1 In the illustrated embodiment, device controller unit 120 controls the supply of DC power to the submodules based on the actual operating DC power required by the connected DC load 122. The target or corresponding value of the current required by the DC load 122 at a selected setpoint (i.e., operating point) is provided by load controller unit 128, which is part of or connected to the DC load 122. Device controller unit 120 then directly controls each submodule. Alternatively, in the illustrated embodiment, device controller unit 120 is configured to determine which submodule will be activated and which will be bypassed, and then provides the target value of the DC power supplied to the submodules or the corresponding voltage or current setpoint (i.e., operating point) value, along with a submodule activation / deactivation signal, to submodule controller unit 130, which is part of or connected to submodules 108, 110, 112, 114, 116, and 118. Submodule controller unit 130 receives its respective current setpoint and activation / deactivation signal and determines its respective necessary switching signals and parameter values.

[0050] exist Figure 2The diagram schematically illustrates a second example of a modular DC-DC converter device according to another embodiment of the present invention. The illustrated modular DC-DC converter device 200 includes input interfaces 202a, 202b, output interfaces 204a, 204b, and a plurality of DC-DC converter sub-modules 206 (N sub-modules 208, 210, 212, 214), which are connected in an ISOP configuration. Figure 2 The diagram shows four of N submodules. Each of the four submodules 208, 210, 212, and 214 shown is capable of providing substantially the same amount of submodule DC power. The DC-DC converter device 200 also includes a device controller unit 220 configured (e.g., programmed) to individually enable and disable the supply of submodule DC power to submodules 208, 210, 212, and 214, such that when the device controller unit 220 disables the supply of submodule DC power to at least one of the submodules 208, 210, 212, and 214, the DC-DC converter device 200 can supply DC power to the DC load 222 (in Figure 2 The system provides the operating DC power required by the DC load 222 for the electrolysis system connected to the output interfaces 204a and 204b. Figure 2 The function of the DC-DC converter device 200 shown corresponds to Figure 1 The functions of the DC-DC converter device 100 shown are illustrated. Figure 2 In the illustrated embodiment, DC-DC converter submodules 208, 210, 212, and 214 are shown as electrically isolated DC-DC converter submodules. Each electrically isolated DC-DC converter submodule 208, 210, 212, and 214 includes DC-to-AC conversion modules 228, 230, 232, and 234 connected to transformer modules 238, 240, 242, and 244 connected to AC-to-DC conversion modules 248, 250, 252, and 254.

[0051] exist Figure 3 The image schematically illustrates an example of an electrolysis apparatus according to another embodiment of the present invention, which is connected to a medium-voltage DC link 314. The electrolysis apparatus 300 includes a plurality of electrolysis systems, wherein... Figure 3 The diagram shows two electrolysis systems 302 and 304, each including at least one row of electrolytic cells 306 and 308. The electrolysis apparatus includes DC-DC converter devices 310 and 312, which can correspond to... Figure 1 The DC-DC converter device 100 shown is or Figure 2The DC-DC converter device 200 shown is connected to the electrolysis systems 302 and 304 to receive power from the DC link 314. Figure 3 The DC link 314 shown is a medium-voltage DC (MVDC) link. DC link 314 can be connected to one or more DC power supplies. Figure 3 In the system shown, DC link 314 is powered by DC power provided by AC-DC converter device 316. Input AC power is provided by connecting to a high-voltage (HV) AC grid 318, which is connected to the AC input side of AC-DC converter device 316 via transformer 320. Transformer 320 is provided as a high-to-medium voltage transformer to adapt the voltage range to the voltage range of the MVDC link.

[0052] exist Figure 4 The image schematically illustrates an example of a method 400 for operating a modular DC-DC converter device according to another embodiment of the present invention, wherein the DC-DC converter device includes an input interface, an output interface, a plurality of N DC-DC converter sub-modules (each sub-module including one or more bypass switches and capable of providing substantially the same amount of sub-module DC power) connected in an ISOP configuration, and a device controller unit.

[0053] The method begins in initial state 402, during which, for example, the programmable device of the device controller unit can be initialized using a computer program product stored in the memory of the device controller unit, and the state of the connected DC load, wherein the DC load is an electrolytic system.

[0054] Then, method 400 continues to perform individual enable and disable steps 404 through the device controller unit to supply submodule DC power to the submodule; and supply step 406, in which the DC-DC converter device performs the supply of its required operating DC power to a DC load connected to the output interface and whose required operating DC power does not exceed (N-1) times the submodule DC power, while the device controller unit disables the supply of submodule DC power to at least one submodule in the submodule using one or more bypass switches.

[0055] exist Figure 4 In the embodiment of method 400 shown, step 404, which individually enables and disables the DC power supply of a submodule, includes several sub-steps. In the first sub-step 410, the operating DC power value of the connected DC load is received. This value can be received from the load controller unit of the connected DC load.

[0056] In the next sub-step 412, the maximum number of submodules that provide the maximum sum of DC power of the submodules is less than or equal to the operating DC power value of the connected DC load is determined.

[0057] Then, one of three optional sub-steps is performed to ensure that as many DC-DC converter submodules as possible are operating at their maximum operating point at any given time. These optional sub-steps depend on the remaining difference between the sum of the submodule DC power supplied by the submodules providing their maximum DC power and the actual operating DC power required by the DC load connected to the output interface of the DC-DC converter device: if the sum equals the operating DC power value, then the maximum number of submodules is activated to supply submodule DC power (step 414). Alternatively, if the maximum number is less than N-1 and the sum is less than the operating DC power value, then the maximum number of submodules is activated to supply submodule DC power, and an additional submodule is activated to provide power less than its maximum submodule DC power (step 416). Alternatively, if the maximum number equals N-1 and the sum is less than the operating DC power value, then the maximum number of submodules is activated to supply submodule DC power, and an additional submodule is activated for a short-term power boost (step 418).

[0058] Even during the power increase and power decrease phases when the operating DC power of the DC load changes (increasing from zero to the maximum operating DC power as the target operating point, or decreasing from the maximum value to zero, respectively), it is preferable to operate the device controller unit to operate as many DC-DC converter submodules as possible at their maximum operating point, i.e., to provide their maximum submodule DC power.

[0059] Step 404, which individually enables and disables the DC power supply of a submodule, also includes a sub-step 408 of periodically changing which submodule's DC power supply is disabled. In the illustrated method, this includes allocating activation times based on the aging status of each submodule across a plurality of submodules. This can be performed using a rotation scheme, where N submodules are disabled sequentially, with at least one disabled at a time.

[0060] For example, the method ends (step 420) when the DC-DC converter device is disabled, or when there is no longer a DC load connected to the output interface, or when the connected DC load no longer needs to operate DC power (e.g., after the DC load is turned off).

[0061] Those skilled in the art will recognize that the boundaries between the blocks are merely illustrative, and alternative embodiments may combine blocks or apply alternative combinations of functions to them. It should be noted that, depending on the embodiment, although the method steps are described and illustrated according to a specific sequence or order of steps, they may be performed at least partially in a different order or simultaneously. Additional steps may be added, and some steps described herein may be omitted.

[0062] Although the present invention has been described and detailed by way of the preferred embodiments shown, the present invention is not limited to the disclosed examples, and those skilled in the art can derive other variations therefrom without departing from the scope of the present invention.

[0063] In summary, a modular DC-DC converter device 100 is provided, comprising input interfaces 102a and 102b, output interfaces 104a and 104b, multiple DC-DC converter submodules (N submodules 108, 110, 112, 114, 116, and 118) connected in an ISOP configuration, each submodule 108, 110, 112, 114, 116, and 118 capable of providing substantially the same amount of submodule DC power, and a device controller unit 120 configured to individually enable and disable the supply of submodule DC power to submodules 108, 110, 112, 114, 116, and 118. The DC-DC converter device 100 is configured to provide the required operating DC power to a DC load 122 connected to the output interfaces 104a and 104b, the required operating DC power of which does not exceed (N-1) times the submodule DC power. 122 is an electrolysis system in which each of the N sub-modules 108, 110, 112, 114, 116, 118 includes one or more bypass switches 108a, 108b, 108c controlled by a device controller unit 120, wherein the device controller unit 120 is configured to use the one or more bypass switches 108a, 108b, 108c of at least one of the N sub-modules to disable the DC power supply of at least one of the N sub-modules 108, 110, 112, 114, 116, 118, and to periodically change which of the sub-modules 108, 110, 112, 114, 116, 118 has its DC power supply disabled, and wherein the device controller unit 120 is also configured to distribute activation time among all the sub-modules in the plurality of N sub-modules according to the aging condition of each individual sub-module.

[0064] In addition, an electrolysis apparatus, a method for operating a modular DC-DC converter device, a computer program product, and a computer-readable storage medium are also provided.

Claims

1. A modular DC-DC converter device (100), comprising: Input interfaces (102a, 102b); Output interfaces (104a, 104b). Multiple N DC-DC converter submodules (108, 110, 112, 114, 116, 118) connected in ISOP configuration, each submodule (108, 110, 112, 114, 116, 118) can provide essentially the same amount of submodule DC power; as well as A device controller unit (120) is configured to individually enable and disable the DC power supply to the submodules (108, 110, 112, 114, 116, 118), wherein, The DC-DC converter device (100) is configured to supply the required operating DC power to a DC load (122) connected to the output interface (104a, 104b) and whose required operating DC power does not exceed (N-1) times the DC power of the submodule. The DC load (122) is an electrolytic system. Each of the N submodules (108, 110, 112, 114, 116, 118) includes one or more bypass switches (108a, 108b, 108c) controlled by the device controller unit (120), wherein the device controller unit (120) is configured to be able to The DC power supply of at least one of the N sub-modules (108, 110, 112, 114, 116, 118) is disabled using one or more bypass switches (108a, 108b, 108c) of at least one of the N sub-modules, and the DC power supply of at least one of the sub-modules (108, 110, 112, 114, 116, 118) is periodically changed, and the device controller unit (120) is also configured to distribute activation time among all sub-modules of the plurality of N sub-modules according to the aging condition of each individual sub-module.

2. The DC-DC converter device of claim 1, wherein the DC-DC converter device (100) is configured to provide the operating DC power required by the DC load (122) with a maximum number of submodules (108, 110, 112, 114, 116) that each provide the maximum submodule DC power, and, if necessary, also with a submodule (118) to provide power less than its maximum submodule DC power.

3. The DC-DC converter device as described in claim 1 or 2, wherein, The DC-DC converter device (100) is configured to supply the required power boost to a DC load (122) connected to the output interface (104a, 104b) that requires a short-term power boost exceeding the operating DC power by enabling the supply of submodule DC power of at least one submodule currently disabled by the device controller unit (120), wherein the operating DC power does not exceed (N-1) times the submodule DC power.

4. The DC-DC converter device as claimed in any of the preceding claims, wherein the submodule is an electrically isolated DC-DC converter submodule (208, 210, 212, 214).

5. The DC-DC converter device of claim 4, wherein the electrically isolated DC-DC converter submodules (208, 210, 212, 214) include DC-to-AC conversion modules (228, 230, 232, 234) connected to transformer modules (238, 240, 242, 244), and the transformer modules (238, 240, 242, 244) are connected to AC-to-DC conversion modules (248, 250, 252, 254).

6. An electrolysis apparatus (300), comprising: One or more electrolysis systems (302, 304), each of the electrolysis systems including at least one row of electrolytic cells (306, 308), wherein the electrolysis apparatus (300) further includes: One or more DC-DC converter devices (310, 312) as claimed in any one of claims 1 to 5, the DC-DC converter devices (310, 312) being configured to connect to the one or more electrolysis systems (302, 304) to receive electrical power from a DC link (314).

7. A method (400) for operating a modular DC-DC converter device, wherein the DC-DC converter device includes an input interface, an output interface, a plurality of N DC-DC converter submodules connected in an ISOP configuration, and a device controller unit, each submodule including one or more bypass switches and capable of providing substantially the same amount of submodule DC power; the method comprising: The device controller unit can individually enable and disable the DC power supply of the submodule using one or more bypass switches (404). as well as The DC-DC converter device supplies the required operating DC power to a DC load connected to the output interface and whose required operating DC power does not exceed (N-1) times the DC power of the submodule, wherein the supply of DC power to at least one of the submodules is disabled by the device controller unit (406), the DC load being an electrolytic system, wherein the step (404) of individually enabling and disabling the supply of DC power to the submodules of the submodules includes periodically changing the supply of DC power to at least one of the submodules that is disabled (408), and wherein the step (408) of periodically changing the supply of DC power to at least one of the submodules that is disabled includes allocating activation time among all submodules of the plurality of submodules according to the aging condition of each individual submodule.

8. The method of claim 7, wherein, The step (404) of individually enabling and disabling the DC power supply of the submodule includes: Receive the operating DC power value (410) of the connected DC load. Determine the maximum number (412) of submodules whose sum of maximum submodule DC power is less than or equal to the operating DC power value of the connected DC load; and If the sum equals the operating DC power value, then the maximum number of submodules is activated to supply the DC power to the submodules (414), or If the maximum number is less than N-1 and the sum is less than the operating DC power value, then the maximum number of submodules is enabled to supply the DC power of the submodules, and an additional submodule is enabled to provide power less than its maximum submodule DC power (416), or If the maximum number is equal to N-1 and the sum is less than the operating DC power value, then the maximum number of submodules is enabled to supply DC power to the submodules, and an additional submodule is enabled for short-term power boost (418).

9. A computer program product comprising a code portion that, when executed on a device controller unit (120) of a DC-DC converter device (100) as claimed in any one of claims 1 to 5, enables the DC-DC converter device (100) to perform the steps of the method (400) as claimed in any one of claims 7 or 8.

10. A computer-readable storage medium comprising the computer program product as described in claim 9.

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