Modular multilevel converter with improved cooling

Abstract

A modular multilevel converter (101) is provided. The modular multilevel converter comprises a plurality of converter cell modules (110) and a support structure (120) comprising a first layer (121) and a second layer (122). A vertical air separation (V) between the converter cell modules of the first layer and the converter cell modules of the second layer provides a hot air flow path (H) from an upper surface of the converter cell modules of the first layer to a space located between the converter cell modules of the second layer, defined by a lateral air separation (L) of the converter cell modules of the second layer, and a cold air flow path (C) for guiding ambient air around the modular multilevel converter to a lower surface of a heat exchanger unit of the converter cell modules of the second layer.

Description

Technical Field

[0001] The present disclosure generally relates to the field of modular multilevel converters (MMCs), such as HVDC transmission systems or flexible alternating current transmission systems (FACTS), and more particularly to an MMC having improved cooling. Background Art

[0002] The MMC comprises interconnected converter cell modules, wherein these interconnected converter cell modules form valves of a converter (or converter station).

[0003] MMCs are typically cooled by pumped water cooling systems that cool the power semiconductor components of the MMC. These systems typically include plastic pipes that carry water from a ground-based pump (and sometimes a deionization system) to the valves of the MMC, which are at high potential. The water is typically rich in ethylene glycol to prevent freezing at low temperatures and is deionized to enhance its dielectric strength. The power semiconductor components can be mounted on a cooler (e.g., an aluminum cooler) that has channels for distributing water along the hot surfaces of the power semiconductor components.

[0004] A complicating factor in using water cooling systems to cool MMCs is that the inverter unit modules of an MMC are located at vastly different electrical potentials, which must be taken into account when designing a water cooling system for the MMC. Consequently, water cooling systems are typically costly, complex, and risky to use to cool MMCs. Furthermore, when a malfunction occurs in the MMC or the water cooling system connected to the MMC, the entire water cooling system may have to be shut down in order to repair the MMC or the water cooling system, increasing the downtime of the MMC. Common malfunctions are leaks during commissioning or operation, which can cause severe damage if moisture enters high-voltage areas, potentially leading to partial discharge, fire, and / or malfunction. Furthermore, the commonly used coolant is a mixture of water and ethylene glycol, which requires special safety and environmental precautions in the event of a leak. An additional complicating factor in using water cooling systems to cool MMCs is that they require water, which may not be available in all areas.

[0005] In view of the foregoing, there is a need to provide a MMC that allows for less complex cooling, is cheaper to install or repair, and can operate in areas where water is not readily available. Summary of the Invention

[0006] In order to at least partially meet at least some of the above requirements, the present disclosure seeks to provide at least an improved modular multilevel converter as defined by the independent claims. Further embodiments are provided in the dependent claims.

[0007] According to one aspect of the present disclosure, a modular multilevel converter (MMC) is provided. The MMC includes a plurality of converter unit modules electrically connected to one another. The converter unit module includes at least one converter unit and at least one heat exchanger unit in thermal contact with the at least one converter unit. The at least one heat exchanger unit includes an upper surface for releasing hot air and a lower surface for collecting cold air. The MMC also includes a support structure comprising a first layer and a second layer. The first layer and the second layer are two consecutive layers along a vertical direction, and the second layer is arranged above the first layer. Each of the first and second layers of the support structure includes at least some converter unit modules. The converter unit modules of the second layer are spaced apart vertically from the converter unit modules of the first layer to provide vertical air separation between the converter unit modules of the first layer and the converter unit modules of the second layer. The converter unit modules of the second layer are spaced apart laterally from one another to provide lateral air separation between them. The vertical air separation provides a hot air flow path (or hot air path) from the upper surface of the heat exchanger unit of the inverter unit module of the first layer to the space defined by the horizontal air separation between the inverter unit modules located on the second layer, and a cold air flow path (or cold air path) for guiding ambient air surrounding the modular multilevel inverter to the lower surface of the heat exchanger unit of the inverter unit module of the second layer.

[0008] In this disclosure, although the terms "hot air flow path" and "cold air flow path" will be used, these terms may be interchangeably replaced with "hot air path" and "cold air path" to name the paths following hot (or warmer) air and cold (or cooler) air, respectively.

[0009] This aspect is based on the following concept, i.e. arranging a plurality of inverter cell modules on the second floor to enhance or optimize the convection of the hot air from the heat exchanger units of the plurality of inverter cell modules on the first floor. In other words, the arrangement of the plurality of inverter cell modules provides improved conditions for releasing the hot air (derived from the heat exchanger units of the plurality of inverter cell modules) from the MMC by convection. This arrangement enables the use of air cooling of the MMC instead of a water cooling system, thereby removing the inherent problems of the water cooling system. In addition, this arrangement is even more efficient when the MMC is arranged outdoors, because there is an unlimited supply of ambient air outdoors, and the released hot air does not need to be removed from the interior of the building. However, the present disclosure is not limited to being arranged in an outdoor MMC, and is also applicable to indoor applications.

[0010] The vertical and lateral separation between the plurality of inverter cell modules spreads the plurality of inverter cell modules over a larger space, thereby reducing the density of heat generated by the plurality of inverter cell modules and allowing the use of air cooling.

[0011] A plurality of inverter cell modules each including a heat exchanger unit allows a single inverter cell module to be replaced, thereby allowing simpler replacement and / or repair of the inverter cell modules in the MMC.

[0012] The heat exchanger units can be configured to transport heat generated by the inverter units to which they are thermally connected. The heat generated by the inverter units is transported to the heat exchanger units to which they are thermally connected. The heat is taken up by the cold (or at least relatively cold) air passing through the heat exchanger units and released as hot air from the upper surfaces of the heat exchanger units.

[0013] It will be appreciated that, under normal ambient conditions, the inverter unit generates heat at a higher temperature than the ambient air surrounding the MMC. Therefore, the heat exchanger unit is arranged to take the heat generated by the inverter unit and release it as hot air (or air that is hotter than the ambient air) via its upper surface. To this end, the heat exchanger unit is configured to collect cooler air (compared to the air released through the upper surface) on its lower surface. Below, the terms "hot" and "cold" will be used to define the air collected on the upper surface and the air collected on the lower surface, respectively, rather than using the terms "hotter air" and "cooler air."

[0014] The vertical direction may be understood as a direction opposite to the direction of gravity, ie, an upward direction.

[0015] The vertical air separation between different inverter cell modules on the first layer and the inverter cell modules on the second layer may vary depending on the size variations (particularly their height) of the inverter cell modules on the first layer. However, such variations are negligible because, in most cases, the inverter cell modules have substantially the same size (i.e., the same height). The vertical air separation between each inverter cell module on the first layer and its nearest corresponding inverter cell module on the second layer (i.e., the inverter cell module directly above it on the second layer) may be substantially equal.

[0016] The plurality of converter unit modules may have substantially the same size, ie, the same height, width, and length. In addition, the distances between the layers of the support structure may also be substantially equal.

[0017] In other cases, variations in vertical air separation between the inverter cell modules of the first layer and the inverter cell modules of the second layer will provide slightly different hot air flow paths.The support structure may stand on the ground, or may be suspended from or attached to a support such as a ceiling or wall.

[0018] In addition, the present disclosure is not limited to a support structure comprising only a first layer and a second layer. The support structure may include substantially any number of layers. For example, the support structure may include a third layer, wherein the first, second, and third layers are three consecutive layers along a vertical direction, and the third layer is arranged above the second layer, and the second layer is arranged above the first layer. Each of these layers may include at least some of the plurality of inverter cell modules. The inverter cell modules of the third layer are spaced apart vertically from the inverter cell modules of the second layer to provide vertical air separation between the inverter cell modules of the second layer and the inverter cell modules of the third layer. The inverter cell modules of the third layer may be spaced apart laterally from each other to provide lateral air separation between them. The vertical separation between the inverter cell modules of the second layer and the inverter cell modules of the third layer may provide a hot air flow path (H) from the upper surface of the heat exchanger unit of the inverter cell modules of the second layer to the space between the inverter cell modules of the third layer, such as defined by the lateral air separation, and a cold air flow path (C) for directing ambient air surrounding the modular multilevel inverter to the lower surface of the heat exchanger unit of the inverter cell modules of the third layer. Therefore, the inverter cell modules of the third layer may be arranged relative to the inverter cell modules of the second layer in the same manner as the inverter cell modules of the second layer are arranged relative to the inverter cell modules of the first layer.

[0019] In addition, the support structure may include additional layers containing at least some of the following inverter cell modules, which can be arranged relative to the inverter cell modules of the layer below these additional layers in the same manner as the inverter cell modules of the second layer are arranged relative to the inverter cell modules of the first layer.

[0020] In this embodiment, two inverter cell modules arranged in one layer above the other of two consecutive layers of the support structure are vertically spaced apart from each other, such that hot air released by the exchanger unit of the lowest inverter cell module (e.g., the inverter cell module of the first layer) is directed into the space defined by the inverter cell module of the upper layer and at least one inverter cell module from the same layer as the inverter cell module of the upper layer (e.g., the second layer). In other words, the two inverter cell modules are vertically spaced apart by a sufficient distance so that hot air released by the lower inverter cell module does not reach the exchanger unit of the inverter cell module of the upper layer.

[0021] Therefore, the inverter cell modules of the second layer may be distributed within the second layer and spaced apart from the inverter cell modules of the first layer, so that hot air from the inverter cell modules of the first layer is directed into spaces between the inverter cell modules of the second layer.

[0022] The inverter unit modules of the second layer can be arranged relative to each other so that the space defined by the lateral air separation forms a channel for the hot air flow path in the middle part of the second layer. The channel can provide improved convection of the hot air, thereby improving cooling efficiency.

[0023] For example, the channel can serve as a chimney or provide a chimney effect for the convection of hot air, wherein the channel is formed within the support structure by the arrangement of the inverter cell modules.

[0024] For a support structure comprising one or more additional layers (i.e., three or more layers in total) arranged in series above a second layer and each layer comprising at least some inverter cell modules, the inverter cell modules of the additional layers may also be laterally spaced apart from each other so as to provide lateral air separation between them, which in turn defines spaces between the inverter cells located in the additional layers. The spaces defined by the laterally spaced inverter cells of different layers may be vertically aligned, which may alternatively be understood as stacking. The alignment or stacking of the spaces defined by the laterally spaced inverter cells of different layers may together form channels within the MMC (or support structure), thereby providing improved convection of hot air (or heat generated by the inverter cell modules).

[0025] The inverter unit modules of the second layer can be arranged along two columns (or rows) spaced laterally from each other so as to provide lateral air separation between them. The space defined by lateral air separation can form a channel for hot air flow path. The first group of inverter unit modules of the second layer can be arranged side by side to form a first row, while the second group of inverter unit modules of the second layer can be arranged side by side to form a second row. The inverter unit modules can be arranged along these two rows so that an air gap is provided between the first row (first group of inverter unit modules) and the second row (second group of inverter unit modules). The air gap provides a channel for convection of hot air.

[0026] For example, the rear side of the first group of inverter cell modules may face the rear side of the second group of inverter cell modules, and there is lateral air separation between them (i.e., between the rear side or back side of the first group of inverter cell modules and the rear side or back side of the second group of inverter cell modules).

[0027] Arranging the inverter cell modules along two columns (or rows) may also provide easier access to the inverter cell modules, thereby facilitating replacement, maintenance, and / or repair of the inverter modules.

[0028] In addition, referring to the above example, in some embodiments, each row of inverter unit modules can be oriented to face away from (or away from) the channel on the side of the inverter unit module including the port connection (e.g., for electrical connection to another inverter unit module), thereby facilitating the electrical connection of the inverter unit modules.

[0029] For a support structure comprising one or more additional layers arranged serially above the second layer, each layer comprising at least some inverter cell modules, the inverter cell modules of the additional layers can be arranged along two columns. The two columns of different layers can be vertically aligned so that the spaces defined by the laterally spaced inverter cells of the different layers are vertically aligned, thereby providing improved convection of hot air through the channels or spaces formed between the inverter cell modules of the columns.

[0030] In some embodiments, the MMC may further include at least one guide member arranged between the one or more inverter unit modules of the first layer and the one or more inverter unit modules of the second layer. In other words, the at least one guide member may be arranged below the one or more inverter unit modules of the second layer and above the one or more inverter unit modules of the first layer. The at least one guide member may be arranged to separate the hot air flow path of the upper surface of the heat exchanger unit originating from the one or more inverter unit modules of the first layer from the cold air flow path of the lower surface of the heat exchanger unit directed to the one or more inverter unit modules of the second layer. By separating the hot air flow path from the cold air flow path, the air collected at the lower surface of the heat exchanger unit can be cooler, thereby improving the cooling efficiency, and the heat can be more efficiently discharged upward (to the second layer or higher layers) and thus discharged from the MMC.

[0031] The guide member can be arranged under a single converter unit module of the second layer, or under a plurality of converter unit modules of the second layer. For example, the guide member can be arranged under a column of converter unit modules of the second layer, or can be used exclusively for a single converter unit module.

[0032] Additionally, the at least one guide member may be configured to block solar radiation that would otherwise block or affect one or more inverter unit modules disposed below the at least one guide member, thereby further improving cooling efficiency.

[0033] Additionally, at least one guide member may be attached to the support structure, thereby providing improved structural rigidity and / or stability, which may reduce twisting and / or deformation of the support structure during, for example, an earthquake.

[0034] It will also be appreciated that providing one or more guide members or plates to separate the hot air flow from the cold air flow also reduces the size requirements for the vertical air separation between different layers of the MMC. In this embodiment, the hot air is directed by convection into the space (or channel) provided by the lateral air separation of the second layer and then into the one or more guide members, thereby reducing the size of the required vertical air separation. This, in turn, can provide a more compact MMC.

[0035] The guide member of the at least one guide member may extend in a plane located between the first layer and the second layer. The plane may be inclined relative to the vertical direction. The guide member may be inclined to more efficiently guide hot air away from the upper surface of the heat exchanger unit of the inverter unit module of the first layer along at least one hot air flow path (i.e., toward the space defined by the lateral air separation between the inverter unit modules of the second layer), and / or guide cold air from the outside of the MMC (or support structure) to the lower surface of the heat exchanger unit of the inverter unit module of the second layer along at least one cold air flow path, thereby increasing the cooling efficiency within the MMC.

[0036] For example, the plane (or guide member) may be inclined at an angle between 30 and 60 degrees relative to vertical.

[0037] It will also be appreciated that, without being tilted (e.g., a tilted plate), a guide member for an individual inverter cell module or a group of inverter cell modules (e.g., a row of inverter cell modules of a layer of a support structure) may include a main body portion comprising at least one surface having a shape for separating hot air and cold air. More specifically, the main body portion of the guide member may include at least one inclined surface for guiding hot air (originating from the upper surface of the heat exchanger unit of the inverter cell module located below the guide member) along at least one hot air flow path (i.e., directed toward the space defined by the lateral air separation between the inverter cell modules of the layer above the guide member), and / or guiding cold air along at least one cold air flow path (i.e., directed from the outside of the MMC (or support structure) toward the lower surface of the heat exchanger unit of the inverter cell module located above the guide member).

[0038] Typically, the guide member of the at least one guide member can be configured to guide hot air from the upper surface of the heat exchanger unit of the inverter unit module of the first layer along at least one hot air flow path. The guide member of the at least one guide member can be arranged to guide hot air along at least one hot air flow path and / or guide cold air along at least one cold air flow path. The at least one guide member can provide improved delivery of hot air. The at least one guide member can be arranged to guide hot air into a space defined by a lateral air separation, which can increase the heat density in the space, thereby increasing the exhaust of hot air, and thus improving the cooling of the MMC.

[0039] The at least one guide member may extend in an upward direction from the side of the support structure toward the space defined by the lateral air separation, along a plane located between the first layer and the second layer. In other words, the guide member is inclined in an upward direction from the periphery of the MMC (or the support structure) toward the center or middle portion of the MMC, thereby facilitating the inflow of cool air from the outside of the MMC and facilitating convection of hot air in the middle portion of the MMC. The edges of the guide members located at the periphery of the MMC are located at a lower level in the vertical direction than the edges of the guide members located at the center or middle portion of the MMC.

[0040] The guide member of the at least one guide member may be a guide plate having a flat shape, a curved shape, or an S-shape. The flat shape may provide improved guidance of air along the air flow path. The curved shape may provide further improved guidance of air along the air flow path. The S-shape may provide even further improved guidance of air along the air flow path.

[0041] The MMC may also include a corona ring extending in a plane between the first and second layers. The corona ring may be a corona shield. The corona ring may be configured to provide electric field shaping. The corona ring may extend in a circular shape in the plane, wherein the circular shape may be arranged along the circumference of the support structure or at a distance therefrom.

[0042] In an MMC comprising a support structure having more than two layers, the MMC may comprise a plurality of corona rings, wherein each corona ring extends in a plane between two consecutive layers of the support structure.

[0043] Additionally, the corona rings may be attached to one or more guide members. Thus, the guide members may be configured as mounting structures for the corona rings.

[0044] A converter cell module in the plurality of converter cell modules may further include a housing in which at least one converter cell of the converter cell module is disposed. The housing may provide protection for the at least one converter cell disposed therein, for example, protecting it from weather conditions. Thus, providing the housing may allow for outdoor installation of the MMC. In particular, each converter cell module of the MMC may include a housing for protecting its converter cells.

[0045] The heat exchanger unit of the inverter unit module can be arranged outside the housing of the inverter unit module, thereby allowing ambient air to easily reach the lower surface of the heat exchanger unit and allowing hot air to easily exit the upper surface of the heat exchanger unit. The heat exchanger unit can be attached to the outside of the housing. The heat exchanger unit can be at the same electrical potential as the housing.

[0046] A converter cell module of the plurality of converter cell modules may include an electrically insulating bushing for connecting a heat exchanger unit of the converter cell module to a housing of the converter cell module. The electrically insulating bushing may allow the heat exchanger unit to be at a different electrical potential than the housing to which it is connected.

[0047] A heat exchanger unit in the plurality of heat exchanger units may be a heat pipe, for example, a loop heat pipe or a pulsating heat pipe.

[0048] A heat exchanger unit in the plurality of heat exchanger units may include at least one condenser and at least one evaporator, the at least one evaporator being fluidly connected to at least one condenser of the heat exchanger unit. The heat exchanger unit may be thermally connected to the at least one inverter unit via the at least one evaporator of the heat exchanger unit. The at least one condenser and the at least one evaporator may be fluidly connected via a pipe or a flexible hose. The pipe or the flexible hose may include electrically insulating segments arranged around a circumference of a portion of the pipe or the flexible hose to allow the at least one condenser and the at least one evaporator to be at different electrical potentials. The heat exchanger unit may include different numbers of condensers and evaporators, for example, one condenser and two evaporators, or two condensers and one evaporator, and may further include a Y-connector to connect the evaporator and the condenser together.

[0049] The inverter unit module in the plurality of inverter unit modules may include at least one fan and / or at least one impeller arranged at the lower surface of the inverter unit module. At least one fan or at least one impeller can support convection of hot air, thereby improving cooling efficiency. Providing at least one fan and / or at least one impeller reduces the requirements for the cooling efficiency of the heat exchanger unit, thereby allowing the use of smaller, simpler, and / or cheaper heat exchanger units. At least one fan and / or at least one impeller can be powered by a power source, for example, one or more Peltier elements, solar panels (which may include batteries), and / or battery cells. The power source can be arranged at at least one fan and / or at least one impeller, thereby reducing the complexity of the MMC, because at least one fan and / or at least one impeller are powered separately and / or locally. Multiple heat exchanger units can be configured as multiple two-phase heat exchanger units. Two-phase heat exchanger units can be more efficient and smaller than traditional heat exchanger units, thereby allowing more efficient cooling of the MMC.

[0050] The two-phase heat exchanger unit may be a thermosyphon. A thermosyphon operates by utilizing natural convection, thereby eliminating the need for a device (e.g., a pump or other liquid circulation equipment) for transporting coolant between the condenser and evaporator. A thermosyphon is a more passive component than a conventional two-phase heat exchanger unit. At least one condenser of the thermosyphon may be positioned above at least one evaporator of the thermosyphon to enable natural convection to function.

[0051] It should be noted that other embodiments using all possible combinations of features described in the above embodiments are foreseeable. Therefore, the present disclosure also relates to all possible combinations of features mentioned herein. Any embodiment described herein can be combined with other embodiments described herein, and the present disclosure relates to all feature combinations. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Exemplary embodiments will now be described with reference to the accompanying drawings, in which:

[0053] Figure 1 is a schematic diagram of a modular multilevel converter according to some embodiments.

[0054] Figure 2a 、 2b , 3a, 3b, 4, and 5 are schematic diagrams of different types of converter unit modules of a multilevel converter according to different embodiments.

[0055] Figure 6a 、 6b , 6c, 6d, and 7b are schematic diagrams of arrangements including a plurality of converter unit modules.

[0056] Figure 7ais a schematic diagram of a modular multilevel converter.

[0057] All figures are schematic, not necessarily to scale, and generally show only parts which are necessary to elucidate embodiments of the invention, wherein other parts may be omitted or merely suggested. Identical reference numerals refer to similar elements throughout. DETAILED DESCRIPTION

[0058] The present invention will be described below with reference to the accompanying drawings, in which exemplary embodiments are shown. However, the inventive concept may be embodied in many different forms and should not be construed as limited to the embodiments presented herein; rather, these embodiments are provided by way of example to convey the scope of the present invention to those skilled in the art. In the figures, unless expressly stated otherwise, identical reference numerals denote identical or similar components having identical or similar functions.

[0059] Figure 1 Schematic diagram of a modular multilevel converter (MMC) 101. MMC 101 includes a support structure 120, which comprises four poles or support columns, and a first layer 121, a second layer 122, and a third layer 123. The three layers 121 to 123 are arranged between the poles. The three layers 121 to 123 are arranged in a continuous layer along a vertical direction Z, with the first layer 121 arranged below the second layer 122, and the second layer 122 arranged below the third layer 123. The relationship between the first layer 121 and the second layer 122 is that of a lower layer and an upper layer. Similarly, the relationship between the second layer 122 and the third layer 123 is that of a lower layer and an upper layer. Therefore, the second layer 122 is a lower layer relative to the third layer 123 and an upper layer relative to the first layer 121.

[0060] The MMC 101 includes a plurality of inverter unit modules 110. Each inverter unit module 110 includes a housing 115 and at least one inverter unit 111 arranged within the housing 115. Each inverter unit module 110 also includes a heat exchanger unit 112, which is arranged outside the housing and in thermal contact with the at least one inverter unit 111. Each heat exchanger unit 112 includes an upper surface 113 for releasing hot air and a lower surface 114 for collecting cold air. The heat exchanger unit 112 may include a heat sink, which may be arranged between the upper surface 113 and the lower surface 114. Each inverter unit module 110 also includes two electrical ports 130, which are configured to allow electrical connection to one or more other inverter unit modules 110.

[0061] Each of the layers 121 to 123 includes some of the inverter cell modules 110. The inverter cell modules 110 of each layer 121 to 123 are arranged along two columns (or rows) laterally spaced apart from each other to provide lateral air separation L therebetween.

[0062] The inverter cell modules 110 of the second layer 122 are spaced apart from the inverter cell modules 110 of the first layer 121 along the vertical direction Z, so as to provide vertical air separation V between the inverter cell modules 110 of the first layer 121 and the inverter cell modules 110 of the second layer 122. Similarly, the inverter cell modules 110 of the third layer 123 are spaced apart from the inverter cell modules 110 of the second layer 122 along the vertical direction Z, so as to provide vertical air separation V between the inverter cell modules 110 of the second layer 122 and the inverter cell modules 110 of the third layer 123. Figure 1 As shown, the spaces defined by the two vertical air separations V can be substantially equal, but can also be different. Additionally, the vertical air separation V can be substantially uniform along the entire space between the first layer 121 and the second layer 122 .

[0063] The vertical air separation V between two layers is determined by the position of the two layers in the support structure along the vertical direction Z and the dimensions (especially the height) of the converter cell modules arranged at these different layers.

[0064] For purposes of illustrating the first and second layers 121 and 122 only, the vertical air separation V provides a hot air flow path H from the upper surfaces 113 of the heat exchanger units 112 of the inverter unit modules 110 of the lower layer 121 to the space defined by the lateral air isolation L between the inverter unit modules 110 of the upper layer 122 arranged above the lower layer 121. The vertical air separation V further provides a cold air flow path C for directing ambient air surrounding the modular multilevel inverter 101 to the lower surfaces 114 of the heat exchanger units 112 of the inverter unit modules 110 of the upper layer 122. The space defined by the lateral air separation L forms a passage for the hot air flow path H in the middle portion of the upper layer.

[0065] It is also understandable that in Figure 1 In the illustrated embodiment, hot air from the upper surface 113 of the heat exchanger unit 112 of the inverter cell module 110 of the first layer 121 can reach any space formed between two adjacent (or neighboring) inverter cell modules 110 of the inverter cell module 110 of the second layer 122, including a channel (or space) formed between two rows (or columns) along which the inverter cell modules 110 of the second layer 122 are arranged.

[0066] In addition, the housing of the inverter unit module may be in the form of a box having six sides (ie, a bottom side, a top side, a front side, a back side, and two lateral sides). Figure 1 In the illustrated embodiment, the inverter unit modules are placed on the corresponding layers by lying on their bottom surfaces with their top surfaces facing the bottom surfaces of the inverter unit modules of the upper layer.

[0067] Furthermore, considering that the front side of the inverter cell modules provides electrical ports for connecting the inverter cell modules to, for example, other inverter cell modules, the inverter cell modules are positioned so that their front sides face away from the space or passage formed between two rows of inverter cell modules. Thus, the back sides of the inverter cell module housings face the space or passage formed between the two rows. In other words, the back sides of the inverter cell modules in the first row face the back sides of the inverter cell modules in the second row, and the first and second rows are separated by a lateral separation L.

[0068] The converter cell modules of a row may be arranged side by side, which means that a lateral side of each converter cell module faces a lateral side of an adjacent converter cell module.

[0069] exist Figure 1 In the illustrated embodiment, the heat exchanger unit of the inverter unit module is arranged on a lateral side of the housing of the inverter unit module.

[0070] Figure 2a and 2b is a multilevel converter (e.g., Figure 1 Schematic diagram of converter unit modules 210a and 210b of the type (or 7a). Converter unit module 210a is equivalent to Figure 1 The inverter cell module 110 shown and described in the related description, except that the heat exchanger unit 112 is arranged on the back side of the housing 115, that is, the side opposite to the side of the housing 115 including the electrical port 130 of the inverter cell module 210a.

[0071] It will be understood that the present disclosure is not limited to the heat exchanger unit 112 being arranged on a specific side of the inverter unit module. However, if the heat exchanger unit of the inverter unit module is arranged on one of the lateral sides or the back, it is beneficial to the arrangement of the inverter unit module, to facilitate the electrical connection of the inverter unit module, and / or to improve the cooling efficiency.

[0072] In addition, the present disclosure is not limited to inverter cell modules including the housing 115, and the heat exchanger unit 112 can be thermally connected to at least one inverter cell of the inverter cell module. However, arranging the inverter cells (i.e., power semiconductor devices) of the inverter cell module within the housing to protect them from the outdoor environment is advantageous for outdoor applications. Arranging the heat exchanger unit outside the housing also provides improved cooling for outdoor applications.

[0073] Figure 2b The inverter unit module 210b and Figure 1 and Figure 2a The difference between the inverter unit modules 110 and 210a shown is that it includes two heat exchanger units 112 arranged on opposite sides (i.e., on two lateral sides of the housing) of the inverter unit module 210b. The inverter unit module 210b may include additional heat exchanger units 112, which may be arranged on other sides (particularly the back side) of the housing 115 of the inverter unit module 210b.

[0074] Figure 3a and 3b is a multilevel converter (e.g., Figure 1 or a schematic diagram of an inverter unit module 310a of the type shown in FIG. 7a).

[0075] Figure 3a The inverter unit module 310a shown may be Figure 1 Examples of converter unit modules used in the illustrated embodiments.

[0076] In this embodiment, the heat exchanger unit 112 of the inverter unit module 310a includes two condensers 117 and two evaporators 118. The heat exchanger unit 112 can be thermally connected to at least one inverter unit of the inverter unit module 110 (or its housing 15) via the evaporator 118. The condenser 117 and the evaporator 118 are arranged on opposite sides of the housing 115 of the inverter unit module 310a. Each of the two condensers 117 is connected to a corresponding evaporator 118 via two fluid connections 119, which can be pipes or flexible tubing. One of the fluid connections 119 is configured to transport coolant from the condenser 117 to the evaporator 118, while the other fluid connection 119 is configured to transport coolant back to the condenser 117. Thus, the coolant is transported in a loop from the condenser 117 to the evaporator 118 and then back to the condenser 117.

[0077] Insulation segments 129 may be disposed around the circumference of the fluid connection 119 connecting the condenser 117 and the evaporator 118 to provide electrical insulation, thereby allowing the condenser 117 and the evaporator 118 to be at different electrical potentials.

[0078] The condenser 117 may be arranged at a first distance from, for example, the top surface of the housing 115 along the vertical direction Z, and the evaporator 118 may be arranged at a second distance from, for example, the top surface of the housing 115 along the vertical direction Z, wherein the second distance is greater than the first distance. Therefore, the condenser 117 and the evaporator 118 are arranged at different heights along the vertical direction Z, thereby allowing the heat exchanger unit 112 to function as a thermosiphon.

[0079] Figure 3b The inverter unit module 310b and Figure 3a The difference between the illustrated inverter unit module 310a is that the heat exchanger unit 112 of the inverter unit module 310b includes a condenser 117 fluidly connected to two evaporators 118. The fluid connection 119 is provided with a Y-connector 139 or splitter to allow cooling liquid from the condenser 117 to reach both evaporators 118, and to allow cooling liquid from both evaporators 118 to reach the condenser 117.

[0080] Figure 4 is a multilevel converter (e.g., Figure 1 or a schematic diagram of an inverter unit module 410 of the type shown in 7a).

[0081] In this embodiment, the inverter unit module 410 includes an electrically insulating sleeve 116 for connecting the heat exchanger unit 112 of the inverter unit module 410 to the housing 115 of the inverter unit module 410, thereby allowing at least a portion of the heat exchanger unit 112 and the housing 115 to be at different electrical potentials. For example, the heat exchanger unit 112 may include at least one condenser (not shown) and at least one evaporator (not shown) fluidically connected via a fluid connection device (not shown). The at least one condenser may be arranged in a portion of the heat exchanger unit that is arranged outside the housing 15, and the at least one evaporator may be arranged inside the housing in thermal contact with the at least one inverter unit. The fluid connection device may be arranged via the electrically insulating sleeve 116.

[0082] Figure 5 is a multilevel converter (e.g., Figure 1 or a schematic diagram of an inverter unit module 510 of the type shown in 7a).

[0083] In this embodiment, the inverter unit module 510 is equipped with three fans 150, which are arranged at the lower surface 114 of the heat exchanger unit 112 of the inverter unit module 510. Figure 5 , three fans 150 are shown, but the inverter unit module can include any number of fans 150, for example, one, two, three, four, five, or more. In addition, the fans 150 can be replaced by (for example) impellers and / or used in combination with impellers. The fans 150 can provide improved convection cooling.

[0084] Figure 6a is a schematic diagram of two converter unit modules 610. The two converter unit modules 610 can be (for example) reference Figure 1 A portion of the plurality of converter unit modules 110 of the MMC. The first converter unit module 610 in the converter unit module may be arranged above the second converter unit module 610. The two converter unit modules 610 may be arranged in (for example) Figure 1 Two corresponding layers of the support structure of the MMC are shown.

[0085] exist Figure 6a In the illustrated embodiment, each inverter cell module includes a guide member 128 disposed below the lower or bottom surface 114 of the corresponding heat exchanger unit of the inverter cell module 610. The guide member 128 is arranged to separate the hot air flow path H originating from the upper surface 113 of the heat exchanger unit 112 of one or more inverter cell modules 610 in a layer below the layer in which the guide member 128 is disposed, from the cold air flow path C directed to the lower surface 114 of the heat exchanger unit 112 of the inverter cell module 610 including the guide member 128.

[0086] exist Figure 6a , the guide member 128 includes a body portion having a shape of a surface for guiding a hot air flow path away from the lower surface 114 of the heat exchanger unit 112 and a surface for guiding a cold air flow path to the lower surface 114 of the heat exchanger unit 112 .

[0087] Figure 6b is a schematic diagram of six converter unit modules 110, which may be MMCs (e.g., Figure 1 1. Thus, Figure 6bA portion of an MMC is shown. The inverter cell modules 110 are arranged in three different layers, including a first layer 121, a second layer 122, and a third layer 123. The second layer 122 is arranged directly above the first layer 121, and the third layer 123 is arranged directly above the second layer 122. Each layer 121 to 123 includes two of the six inverter cell modules 110. The inverter cell modules 110 of the second and third layers 122 and 123 are spaced apart from the inverter cell modules 110 of the first and second layers 121 and 122, respectively, along a vertical direction Z to provide vertical air separation V between the inverter cell modules 110 of the first and second layers 121 and 122, and between the inverter cell modules 110 of the second and third layers 122 and 123. Furthermore, the inverter cell modules 110 of each layer 121 to 123 are spaced apart laterally from each other to provide lateral air separation L.

[0088] This portion of the MMC further includes four guide members 125, wherein the guide members 125 are guide plates 125 having a flat shape. However, the guide plates 125 may have other shapes, such as a curved shape or an S-shape. Figure 6c and 6d are provided to illustrate these alternative shapes of the guide members 125. Each guide plate 125 is arranged below several converter unit modules 110 of a certain layer, although Figure 6b Only one is shown (because it is a cross-sectional view of the MMC).

[0089] Two of the four guide members 125 extend in respective planes between the first layer 121 and the second layer 122, and the other two of the four guide members 125 extend in respective planes between the second layer 122 and the third layer 123. These planes are inclined relative to the vertical direction Z so that the guide plates 125 extend from the sides or periphery of that portion of the MMC toward the space defined by the lateral air separation in the middle portion of the MMC. The guide plates 125 extend in the Figure 6b 123. The guide plates 125 are shown as being adjacent to the layers 121 to 123 located directly above them. However, the ends of the guide plates 125 located in the middle portion of the MMC are spaced apart from each other to provide a path for the exhaust of hot air. The guide plates may also be attached to the portion of the support structure that forms the layers 121 to 123 to which they are adjacent.

[0090] Provides such as Figure 6b 、 6cThe plate-shaped guide member 125 shown in FIG6d is advantageous in that it prevents hot air from passing between the two sides of two adjacent unit modules in the same row (column). Instead, hot air originating from a layer below the guide member 125 is directed to the area (or space) formed between the two rows of inverter unit modules 110.

[0091] It is understandable that in Figure 6a In FIG. 1 , the guide member 125 is considered to be a guide member attached to each converter unit module 610a, while in FIG. Figure 6b In FIG. 1 , the guide member 125 is considered to be a guide member attached to a support structure below each plurality of converter unit modules 110 .

[0092] Figure 6b 、 6c , 6d shown in the converter unit module 110 can be such as reference Figure 2a 、 2b , 3a, 3b, 4, and the converter unit module described in 5.

[0093] Figure 7a is a schematic diagram of a modular multilevel converter 701 according to an embodiment.

[0094] Figure 7a The MMC 701 shown and Figure 1 The difference between the MMCs shown is that Figure 7a The illustrated MMC 701 is further provided with four pairs of electrically insulating corona rings 127. Each pair of electrically insulating corona rings 127 extends in one of four substantially parallel and spaced-apart planes. The first plane on which the first pair of electrically insulating corona rings 127 extend is located below the first layer 121. The second plane on which the second pair of electrically insulating corona rings 127 extend is located between the first layer 121 and the second layer 122. The third plane on which the third pair of electrically insulating corona rings 127 extend is located between the second layer 122 and the third layer 123. The fourth plane on which the fourth pair of electrically insulating corona rings 127 extend is located above the third layer 123. The electrically insulating corona rings 127 can be attached to the inverter cell module 110 and / or the support structure 120.

[0095] Figure 7b is a schematic diagram of six converter unit modules 110, wherein these converter unit modules can be (for example) Figure 1 and 7a The MMC shown is a portion of a plurality of converter unit modules 110. Therefore, Figure 7b A portion of the MMC is shown. Figures 6b to 6d , Figure 7b is a cross-sectional or side view of the portion of the MMC.

[0096] Figure 7b The parts of the MMC shown and (for example) Figure 6b The difference between the portion of the MMC shown is that it also includes a plurality of electrically insulating corona rings 127 (a cross section of these corona rings is shown). The electrically insulating corona rings 127 are attached to the edge of the underlying guide plate 125, i.e., the edge closest to the periphery of the MMC, which can improve the stability of the arrangement.

[0097] While the invention has been described in the drawings and foregoing description, such description should be considered illustrative or exemplary rather than restrictive; the invention is not limited to the disclosed embodiments. Other variations to the disclosed embodiments will be apparent to those skilled in the art upon studying the drawings, the present disclosure, and the appended claims in practicing the claimed invention.

[0098] For example, although Figure 7b The embodiment shown is Figure 6b The embodiment shown is compared to describe the arrangement of the corona ring 127, but it is understood that the arrangement of the corona ring 127 can be described in detail. Figure 6c and 6d Corona rings are similarly provided in the MMC or inverter cell module group of the illustrated embodiment.

[0099] In the accompanying claims, the word "comprising" does not exclude other elements or steps, and the indefinite article "a" or "an" does not exclude a plurality. The mere fact that certain measures are recited in mutually different dependent claims does not indicate that a combination of these measures cannot be used to advantage. Any reference signs in the claims should not be construed as limiting the scope.

Claims

1. A modular multilevel converter (101), comprising: A plurality of converter unit modules (110) electrically connected to each other, wherein the converter unit modules include: at least one converter unit (111), and at least one heat exchanger unit (112) in thermal contact with the at least one inverter unit, wherein the at least one heat exchanger unit comprises an upper surface (113) for releasing hot air and a lower surface (114) for collecting cold air, a housing (115) in which the at least one inverter unit is arranged, wherein the at least one heat exchanger unit is arranged outside at least one of the respective lateral sides and rear side of the housing, and A support structure (120) comprising a first layer (121) and a second layer (122), wherein the first layer and the second layer are two consecutive layers along a vertical direction, and the second layer is arranged above the first layer, wherein each of the first layer and the second layer of the support structure comprises at least some of the inverter cell modules, wherein the inverter cell modules of the second layer are spaced apart from the inverter cell modules of the first layer along the vertical direction so as to provide vertical air separation between the inverter cell modules of the first layer and the inverter cell modules of the second layer, and wherein the inverter cell modules of the second layer are spaced apart from each other laterally so as to provide lateral air separation therebetween; The vertical air separation provides a hot air flow path from the upper surface of the heat exchanger unit of the inverter unit module of the first layer to the space defined by the horizontal air separation between the inverter unit modules located on the second layer, and a cold air flow path for guiding ambient air surrounding the modular multilevel inverter to the lower surface of the heat exchanger unit of the inverter unit module of the second layer.

2. The modular multilevel converter according to claim 1, wherein: The inverter cell modules of the second layer are arranged relative to each other such that the space defined by the lateral air separation forms a passage for the hot air flow path in a middle portion of the second layer.

3. The modular multilevel converter according to claim 1 or 2, wherein: The inverter cell modules of the second layer are arranged along two rows that are laterally spaced apart from each other to provide the lateral air separation therebetween.

4. The modular multilevel converter according to claim 1 or 2, further comprising at least one guide member (125), wherein the at least one guide member is arranged between the one or more converter unit modules of the first layer and the one or more converter unit modules of the second layer, wherein The at least one guide member is arranged to separate a hot air flow path originating from an upper surface of the heat exchanger unit of the one or more inverter unit modules of the first layer from a cold air flow path directed to a lower surface of the heat exchanger unit of the one or more inverter unit modules of the second layer.

5. The modular multilevel converter according to claim 4, wherein: A guide member of the at least one guide member extends in a plane located between the first layer and the second layer, wherein the plane is inclined with respect to the vertical direction.

6. The modular multilevel converter according to claim 5, wherein: The guide members extend along the plane in an upward direction from a side of the support structure toward a space defined by the lateral air separation.

7. The modular multilevel converter according to claim 4, wherein: The guide member of the at least one guide member is a guide plate having a flat shape, a curved shape, or an S-shape.

8. The modular multilevel converter according to claim 1 or 2, further comprising a corona ring (127) extending in a plane between the first layer and the second layer.

9. The modular multilevel converter according to claim 1 or 2, wherein: A converter cell module of the plurality of converter cell modules comprises an electrically insulating bushing (116) for connecting a heat exchanger unit of the converter cell module to a housing of the converter cell module.

10. The modular multilevel converter according to claim 1 or 2, wherein: A heat exchanger unit of the plurality of heat exchanger units comprises at least one condenser (117) and at least one evaporator (118), the at least one evaporator being fluidically connected to the at least one condenser of the heat exchanger unit; and wherein the heat exchanger unit is thermally connected to the at least one inverter unit via the at least one evaporator of the heat exchanger unit.

11. The modular multilevel converter according to claim 1 or 2, wherein: Each of the plurality of inverter unit modules includes at least one fan (150) arranged at a lower surface of a heat exchanger unit of the inverter unit module.

12. The modular multilevel converter according to claim 1 or 2, wherein: The plurality of heat exchanger units are configured as a plurality of two-phase heat exchanger units.

13. The modular multilevel converter according to claim 12, wherein: The two-phase heat exchanger unit is a thermosyphon.

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