Device with capacitors

Abstract

A device (20) has a plurality of capacitors (31) and a first material (40), which first material (40) is provided at least partially, at least in certain areas on an outside (32) of the capacitors (31), and which first material (40) is designed as a phase-change material.

Description

[0001] The invention relates to a device with capacitors.

[0002] KR 10 2020 0 117 704 A shows a printed circuit board carrying an inverter and a capacitor. A phase-change material is provided between a housing and a capacitor.

[0003] DE 10 2019 213 153 A1 shows an intermediate circuit capacitor which has a latent heat storage device made of phase change material which is in thermal connection with busbars.

[0004] US 2017 / 0 169 948 A1 shows an assembly with a capacitor and a heat sink, which heat sink has a phase change material.

[0005] WO 2016 / 077 619 A1 shows a capacitor encased in layers of a phase change material.

[0006] WO 2011 / 117 221 A1 shows a battery designed as a capacitor module with a casing made of a phase change material.

[0007] EP 2 825 008 A1 shows a direct cooling of power electrical capacitors with a dielectric fluid.

[0008] DE 10 2010 012 949 A1 shows a capacitor module with a plurality of interconnected cells of double-layer capacitors and / or hybrid capacitors and with a means for tempering the cells, wherein the means for tempering the cells has phase change material in contact.

[0009] WO 2014 / 134 143 A1 shows an energy storage arrangement.

[0010] DE 10 2011 007 315 ​​A1 shows a storage unit with an energy storage device, wherein the positive or negative terminal is thermally connected to a thermally conductive cooling element.

[0011] US 2012 / 0 327 596 A1 shows a thermal management system that uses a phase change material to assist with thermal stress.

[0012] EP 3 468 325 A1 shows a heat exchanger with a phase change material for influencing a coolant temperature.

[0013] EP 2 568 790 A1 shows a cooling device with a base plate, on one side of which channels for a coolant are provided and on the other side of which a phase change material is provided.

[0014] US 2016 / 0 226 042 A1 shows a housing for thermal management in an electrochemical cell.

[0015] It is therefore an object of the invention to provide a new device with capacitors.

[0016] This problem is solved by the subject matter of claim 1.

[0017] A device comprises a plurality of capacitors and a first material, which first material is provided at least partially, at least in regions, on an outer side of the capacitors, and which first material is designed as a phase change material. The phase-change material reduces the load on the cooling system and helps with thermal overload peaks. In addition, the phase-change material enables mechanical stabilization and vibration dampening.

[0018] The device has a fluid guide channel, which fluid guide channel is provided for receiving a dielectric fluid, and which fluid guide channel is designed to enable a thermal operative connection of a dielectric fluid with - the first material, - the capacitors, or - the first material and the capacitors.

[0019] Such a fluid guide channel is advantageous in combination with the first material, and the two cooling technologies complement each other advantageously in different temperature ranges.

[0020] The device comprises a pump designed to pump a dielectric fluid through the fluid guide channel. This improves the cooling effect of the dielectric fluid.

[0021] According to a preferred embodiment, a dielectric fluid is provided in the fluid guide channel. Dielectric fluid is electrically non-conductive and therefore reduces the risk of a short circuit.

[0022] According to a preferred embodiment, the device comprises a converter, and the capacitors are at least partially designed as intermediate circuit capacitors for the converter. In converters, large power losses can occur in the area of ​​the capacitors, and cooling is particularly advantageous.

[0023] According to a preferred embodiment, the converter is designed as a multi-stage converter. Multi-stage converters offer greater flexibility in the voltages generated.

[0024] According to a preferred embodiment, the converter is designed as a multi-stage, modular converter. Such converters can, for example, generate different voltages from a plurality of battery cells and are suitable, for example, for direct driving an electric motor.

[0025] According to a preferred embodiment, the converter is designed for a first maximum electrical power, and the first material is selected such that it undergoes a phase change at an outside temperature of 25°C within a power range that lies between 5% and 50% of the first maximum electrical power of the converter. For example, a power range between 10% and 20% can be selected. This enables the first material to perform a cooling function during low-load operation. During high-load operation, the first material is preferably liquid and therefore enables good heat conduction. The specified outside temperature, which can also be referred to as the ambient temperature, serves to ensure the reproducibility of the measurements.

[0026] According to a preferred embodiment, the converter is designed for a first maximum electrical power, and the first material is selected such that it undergoes a phase change at an outside temperature of 25°C in a power range that lies between 60% and 100% of the first maximum electrical power. This makes the entire cooling system more stable in the upper power range. The power range can, for example, be between 70% and 90%.

[0027] According to a preferred embodiment, the capacitors are arranged side by side in such a way that at least two rows and two columns are provided, preferably at least three rows and three columns. This matrix-like arrangement has proven very advantageous for applying the first material.

[0028] According to a preferred embodiment, the device comprises an electrical connection device, and the capacitors are electrically connected to the electrical connection device. Such a connection device facilitates assembly and enables a low-resistance electrical connection.

[0029] According to a preferred embodiment, the electrical connecting device comprises busbars. Busbars are also suitable for high currents.

[0030] According to a preferred embodiment, the first material is designed to be solid at a first material temperature of 20°C to enable a phase transition to a liquid state during operation. This transition is advantageous, and in the liquid state, the first material often has better thermal conductivity.

[0031] According to a preferred embodiment, the first material is designed to undergo a crystal structure transition from a first lattice configuration to a second lattice configuration at a predetermined temperature. Such a first material changes the lattice configuration in certain regions and enables a comparatively large amount of latent heat to absorb it.

[0032] According to a preferred embodiment, the first material is provided in one or more sheaths. This allows for better dimensional stability, particularly during a transition to a liquid phase.

[0033] According to a preferred embodiment, the at least one coating comprises a microencapsulation. Overall, heat transfer is better with microencapsulation than with macroencapsulation.

[0034] Further details and advantageous developments of the invention will become apparent from the exemplary embodiments described below and illustrated in the drawings, which are in no way to be understood as limiting the invention, as well as from the dependent claims. Fig. 1 shows a side view of a first embodiment of a device with capacitors and with a first material, Fig. 2 in a plan view the device of Fig. 1, Fig. 3 shows a side view of a second embodiment of a device with capacitors and with a first material, Fig. 4 in a plan view the device of Fig. 3, and Fig. 5 a diagram of an electrical performance for the design of the first material.

[0035] In the following, identical or equivalent parts are provided with the same reference symbols and are usually described only once. The description builds on each figure to avoid unnecessary repetition.

[0036] Fig. 1 shows a device 20 in a side view, and Fig. 2 shows the device 20 of Fig. 1 in a top view.

[0037] The device 20 has an electrical connection device 22 and a plurality of capacitors 31. The capacitors 31 have, at least partially, at least in regions, a first material 40 on an outer side 32, which first material 40 is designed as a phase-change material. Phase-change material is referred to in English as PCM.

[0038] The electrical connecting device 22 is electrically connected to the capacitors 31.

[0039] The electrical connection device 22 preferably has busbars 24.

[0040] In the exemplary embodiment, the capacitors 31 are arranged in three rows and four columns. Preferably, the capacitors 31 are arranged next to one another in such a way that at least two rows and two columns are provided, preferably at least three rows and three columns.

[0041] The first material 40 is preferably provided in one or more enclosures 41. Particularly during a transition to a liquid phase, it might otherwise no longer be guaranteed that the first material 40 remains in the region of the capacitors 31. The enclosure 41 can advantageously have a microencapsulation. This is advantageous over pure macroencapsulation because the first material conducts heat less well in the solid state than in the liquid state, and upon cooling, the outer regions are the first to solidify, preventing effective heat transfer.

[0042] Tests have shown that the cooling effort can be reduced by using the first material 40.

[0043] The first material 40 also enables comparatively rapid absorption of heat.

[0044] Phase change materials are materials that can be used technically by releasing or absorbing heat or cold during their phase change, depending on their respective melting point and the ambient temperature.

[0045] The phase change between solid and liquid, or the phase change between liquid and gas, can be utilized. Due to the smaller volume change, the transition between solid and liquid is technically advantageous, and in the liquid phase, the first material 40 can conduct heat well.

[0046] The phase change can also occur within the solid phase. For this purpose, the first material 40 is preferably designed to undergo a transition of a crystal structure from a first lattice configuration to a second lattice configuration at a predetermined temperature. This also requires (or releases) latent heat, which can be used for cooling.

[0047] Elements made of phase-change materials are latent heat storage devices that store a high proportion of heat and cold energy and release it as heat in a changed phase as needed. Salts (e.g., Glauber's salt, sodium acetate) or organic compounds (e.g., paraffins, fatty acids) are used as storage media. These change their state (liquid to solid) under thermal loads, absorbing or releasing heat energy.

[0048] Preferably, a housing is provided around the capacitors 31, such as the housing 88 in Fig. 3 is shown.

[0049] Fig. 3 shows a further embodiment of the device 20 in a side view, and Fig. 4 shows the device 20 of Fig. 3 in a top view.

[0050] The following is based on the description of Fig. 1 and Fig. 2 explains the differences.

[0051] The device 20 has a housing 88 which forms a fluid guide channel 82.

[0052] The fluid guide channel 82 is provided for receiving a dielectric fluid 80 and is designed to enable a thermal connection of the dielectric fluid 80 with - the first material 40, - the capacitors 31, or - the first material 40 and the capacitors 31.

[0053] A schematically indicated pump 84 is designed to pump the dielectric fluid 80 through the fluid guide channel 82.

[0054] A schematically indicated line 86 closes a coolant circuit with the pump 84 and the fluid guide channel 82.

[0055] The device 20 has a converter 35, and the capacitors 31 are at least partially designed as intermediate circuit capacitors for the converter 35. Cooling the intermediate circuit capacitors is particularly advantageous because it reduces the losses of the converter 35.

[0056] The converter 35 is preferably designed as a multi-stage converter, in particular as a multi-stage, modular converter. Such converters 35 can generate an AC voltage, for example, from a plurality of battery cells.

[0057] Fig.Figure 5 shows a diagram in which an arrow indicates the electrical power. The maximum power of the device 20 is indicated as P_max, and this value corresponds to 100%. Conversely, when no power is required, the electrical power percentage is 0%.

[0058] For the design of the device 20, it is advantageous to select the first material 40 with a suitable temperature for the phase change.

[0059] The temperature for the phase change can be selected as follows.

[0060] The first material 40 is selected such that it undergoes a phase change at an outside temperature of 25°C within a power range 91 that lies between 5% and 50% of the maximum electrical power. Thus, the power range 91 can range, for example, from 10% to 40% or from 10% to 50%.

[0061] This allows the material 40 to completely assume passive cooling at low loads, and active cooling only occurs in high loads, where the material 40 is in a liquid state and therefore well suited for heat conduction. This allows the pumping power of pump 84 to be reduced at low power levels of the device 20, allowing the device 20 to operate efficiently.

[0062] Alternatively, the first material 40 can be selected such that it undergoes a phase change at an outside temperature of 25°C within a power range 92 that lies between 60% and 100% of the maximum electrical power. For example, the power range 92 lies between 65% and 100%.

[0063] This enables good cooling performance in the upper performance range.

Claims

[1] Device (20) which has a plurality of capacitors (31), a fluid guide channel (82), a pump (84) and a first material (40), which first material (40) is arranged at least partially, at least in regions, on an outer side (32) of the capacitors (31), which first material (40) is designed as a phase change material, wherein the fluid guide channel (82) is designed to receive a dielectric fluid (80), and wherein the fluid guide channel (82) is configured to enable a thermal operative connection of a dielectric fluid (80) with the first material (40) and the capacitors (31), wherein the pump (84) is designed to pump a dielectric fluid (80) through the guide channel (82). [2] Device (20) according to claim 1, wherein a dielectric fluid (80) is arranged in the fluid guide channel (82). [3] Device (20) according to one of the preceding claims, which has a converter (35), and in which the capacitors (31) are at least partially designed as intermediate circuit capacitors for the converter (35). [4] Device (20) according to claim 3, wherein the converter (35) is designed as a multi-stage converter, in particular as a multi-stage, modular converter. [5] Device (20) according to claim 3 or 4, wherein the converter (35) is designed for a first maximum electrical power, and wherein the first material (40) is selected such that it carries out a phase change at an outside temperature of 25 °C in a first power range (91), which first power range (91) is in the range of 5% to 50% of the first maximum electrical power. [6] Device (20) according to one of claims 3 to 5, in which the converter (35) is designed for a first maximum electrical power, and in which the first material (40) is selected such that it carries out a phase change at an outside temperature of 25 °C in a second power range (92), which second power range (92) is in the range of 60% to 100% of the first maximum electrical power. [7] Device (20) according to one of the preceding claims, in which the capacitors (31) are arranged next to one another in such a way that at least two rows and two columns are formed, preferably at least three rows and three columns. [8] Device (20) according to one of the preceding claims, which has an electrical connection device (22), and in which the capacitors (31) are electrically connected to the electrical connection device (22). [9] Device (20) according to claim 8, wherein the electrical connection device (22) comprises busbars (24). [10] Device (20) according to one of the preceding claims, wherein the first material (40) is designed to be solid at a temperature of the first material (40) of 20 °C in order to enable a phase transition to a liquid state during operation. [11] Device (20) according to one of the preceding claims, wherein the first material (40) is designed to carry out a transition of a crystal structure from a first lattice configuration to a second lattice configuration at a predetermined temperature. [12] Device (20) according to one of the preceding claims, in which the first material (40) is arranged in one or more enclosures (41). [13] Device (20) according to claim 12, wherein the at least one enclosure (41) comprises a microencapsulation.

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