Cooling system, inverter and cooling process

Abstract

Cooling system (1) suitable for use with an electronic device with a heat sink (2), a heat sink (3) which is in heat-transferring contact with the heat sink, a nozzle (4), a fluid supply device (5) which supplies a fluid to the nozzle (4), and an actuator, characterized in that the actuator is configured to open the nozzle (4) in response to a trigger signal from a controller (6) so that the nozzle (4) sprays the fluid in the direction of the heat sink (3).

Description

[0001] The invention relates to a cooling system, an inverter with a cooling system and a method for operating a cooling system. Problem

[0002] In light of climate change, there is an effort to replace fossil fuel energy production with energy production from renewable energy sources. The most common renewable energy sources are wind and solar. Unlike wind energy, solar energy can also be converted into electricity using domestic and private photovoltaic systems. This electricity is used in the generating household or fed into a public energy grid. To ensure the stability of the energy supply grid, even with multiple feeders, such as private photovoltaic systems, operators of certain parts of the energy supply grid have established regulations regarding the feed-in of electrical power.For example, an inverter that converts the direct current from a photovoltaic system or other direct current source into feedable alternating current must inject a high level of electrical power into the power grid when the grid frequency drops, in order to "support" it, i.e., to attempt to raise the grid frequency by injecting active power. In other cases, it may be necessary to inject high levels of reactive power and / or reactive current into the power grid. Both active and reactive power are defined, in particular, by high current, since the voltage is determined by the power grid.

[0003] In this case, it may be necessary for the inverter to provide a current that is greater than the maximum current permitted for the inverter, whereby the power electronics in particular heat up considerably due to the high current provided. This heat must then be dissipated or the power electronics must be cooled before another high current can be provided, also known as an overcurrent event. If another overcurrent event occurs while the heat from the previous overcurrent event is still being dissipated, the power electronics would be damaged by excessive heat, so that the inverter control system prohibits the provision of an overcurrent in order to prevent damage. During this time, the provision of an overcurrent is therefore not possible, which means that the energy supply grid can only be supported within the maximum permissible current and not through an overcurrent.

[0004] The prior art discloses dissipating the heat from power electronics to heat sinks and cooling them with ambient air or an artificially generated airflow. However, this type of cooling may be insufficient.

[0005] Furthermore, German patent application DE 10 2008 029 887 A1 discloses a cooling system for an inverter in a vehicle, wherein the power electronics are contained in a microelectronic die. At higher temperatures, a fluid is sprayed onto this die, thereby cooling the die.

[0006] This gives rise to the task of providing a cooling system that can cool the power electronics of an inverter as quickly as possible.

[0007] This problem is solved by the subject matter of the main claim. Aspects and further developments of the invention are the subject matter of the subsidiary and dependent claims.

[0008] To achieve the object, the cooling system according to the invention, which is suitable for use with an electronic device, comprises, as a first aspect of the invention, a heat sink, a heat sink in heat-transferring contact with the heat sink, a nozzle, a fluid supply device that supplies a fluid to the nozzle, and an actuator. The cooling system is particularly characterized in that the actuator is configured to open the nozzle in response to a trigger signal, so that the nozzle sprays the fluid toward the heat sink.

[0009] The cooling system described above is therefore suitable for use with an electronic device or for being mounted on such an electronic device such that the electronic device, and in particular heat-sensitive components of the electronic device such as power electronics, can be cooled. For the sake of simplicity and clarity, all possible components that can or must be cooled are referred to as components to be cooled. Furthermore, the electronic device can be any type of electronic device that converts current. This means that the electronic device can be an AC-DC converter, a DC-AC converter, an AC-AC converter, or a DC-DC converter.

[0010] According to the invention, the heat sink is intended for contact with the electronic device or the components to be cooled. The heat sink is preferably made of a material with good thermal conductivity, such as copper. Various shapes of the heat sink are conceivable, which can vary depending on the application. It is advantageous if the contact surface with an electronic device or components to be cooled is as large as possible. This means that the shape of the heat sink depends on the components to be cooled.

[0011] The heat sink according to the invention can be a conventional heat sink. For example, the heat sink is designed as cooling fins, which have the advantage of a large surface area. This surface area dissipates heat to the surrounding media.

[0012] The general purpose of the heat sink is to absorb heat from the components to be cooled and to transfer it to the heat sink via a contact area, which then transfers the absorbed heat to a surrounding medium. In this way, among other things, the heat generated by the components to be cooled can first be transferred to the heat sink via a contact surface with good heat transfer and then efficiently transferred to the environment via the heat sink. For this purpose, it is not only relevant that the heat sink has a large contact surface with the components to be cooled, but also that the heat transfer between the heat sink and the heat sink is equally effective. According to the invention, heat-transferring contact between the heat sink and the heat sink can be understood to mean that the contact point between the heat sink and the heat sink is designed to transfer heat from the heat sink to the heat sink as effectively as possible. There are various possibilities for this.For example, the contact surfaces between the heat sink and the heat sink can be polished, a thermal paste can be applied to the contact surface between the heat sink and the heat sink, or the contact surface between the heat sink and the heat sink can be designed so that the contact surface is as large as possible.

[0013] The nozzle according to the invention can be a conventional nozzle suitable for dispensing a fluid in a defined manner. For example, it is conceivable that the nozzle is a mist nozzle that nebulizes the fluid if the fluid is a liquid. It is also conceivable that the nozzle is suitable for dispensing a fluid that is a gas with a specific spray radius or spray distance.

[0014] The fluid supply device according to the invention is suitable for supplying a fluid to the nozzle. The fluid supply device can be of many types. For example, the fluid can be supplied to the nozzle via a hose from a fluid container. Alternatively, a line continuously filled with a fluid can serve as the fluid supply device, such as a gas line or a water or other liquid line. The fluid can be adapted to the ambient properties. This means that a different fluid can be used in warmer environments than in cooler environments.

[0015] Other environmental characteristics may include open flame sources or areas with a high risk of ignition, humidity, etc. Furthermore, the fluid is selected based on its heat capacity and, in the case of a liquid, its enthalpy of vaporization. Fluids with higher heat capacity and enthalpy of vaporization are preferred, as their cooling effect is greater than that of air as the ambient medium for the heat sink.

[0016] The actuator according to the invention can be implemented as a valve arranged in the nozzle or the fluid supply device. The actuator serves to enable a flow of fluid from the nozzle. In the exemplary case of a valve in the nozzle, the valve opens in response to a trigger signal sent by a controller, so that the nozzle supplied with fluid from the fluid supply device releases the fluid flow. In the exemplary case of a valve in the fluid supply device, the fluid flow to the nozzle is released when the valve opens.

[0017] The cooling system according to the invention makes it possible to provide increased cooling performance by spraying the fluid onto the heat sink. Furthermore, the cooling performance can be adapted to the particular device to which the cooling system is attached by selecting a specific fluid. This makes it possible to spray no fluid during normal operation, while improving the cooling performance of the cooling system during operation with the provision of an overcurrent. This allows components to be cooled effectively, extends their service life, and extends the time during which an overcurrent can be provided.

[0018] According to one embodiment of the cooling system, the fluid supply device comprises a fluid container which has an internal pressure which is higher than the ambient pressure.

[0019] The design of the fluid supply device as a fluid reservoir with an internal pressure higher than the ambient pressure allows the cooling system to be used even in areas where there is no infrastructure for a fixed supply line. The increased internal pressure ensures that the fluid in the fluid reservoir also flows out when the actuator is opened by the trigger signal.

[0020] According to one embodiment of the cooling system, the fluid supply device comprises a hose that can be connected to a fluid source.

[0021] The fluid supply device, which is implemented as a conduit and connectable to a fluid source, offers the advantage of a continuous fluid supply via the hose from the fluid source. Thus, there can be no situation where there is no fluid available to spray from the nozzle and thus for cooling.

[0022] According to one embodiment of the cooling system, the fluid supplied to the nozzle is a liquid, preferably water.

[0023] If the fluid used for cooling is a liquid, the cooling performance of the cooling system according to the invention is further improved by the fact that when a liquid absorbs heat and transforms from a liquid state to a gaseous state, it evaporates. As already mentioned, evaporation requires a certain amount of energy in the form of heat. Water is the preferred fluid because it is non-toxic, has a boiling point at a reasonable temperature, and is widely available.

[0024] One aspect of the invention features a cooling system suitable for use with an electronic device, comprising a heat sink, a heat sink in heat-transferring contact with the heat sink, a nozzle configured to generate a liquid mist, and a liquid supply device that supplies a liquid to the nozzle. The cooling system is particularly characterized by an air flow generation device that generates an air flow such that the air flow flows around the heat sink, and an actuator configured to open the nozzle in response to a trigger signal, so that the nozzle introduces the liquid mist into the air flow.

[0025] The general purpose of the heat sink is to absorb heat from the components to be cooled and dissipate it via a contact point on the heat sink, which then dissipates the absorbed heat to a surrounding medium. In this way, among other things, the heat generated by the components to be cooled can first be dissipated to the heat sink through a good contact surface and then efficiently dissipated to the environment via the heat sink. For this, it is not only relevant that the heat sink has a large contact surface with the components to be cooled, but also that heat is transferred between the heat sink and the heat sink. The heat-transferring contact between the heat sink and the heat sink according to the invention can be understood as meaning that the contact point between the heat sink and the heat sink is designed to transfer heat from the heat sink to the heat sink as effectively as possible. There are various possibilities for this.For example, the contact surfaces between the heat sink and the heat sink can be polished, a thermal paste can be applied to the contact surface between the heat sink and the heat sink, or the contact surface between the heat sink and the heat sink can be designed so that the contact surface is as large as possible.

[0026] The nozzle according to the invention can be a conventional nozzle suitable for dispensing a liquid in a defined manner. Here, the nozzle is designed as a mist nozzle that nebulizes the liquid. It is also conceivable for the nozzle to be designed to dispense a liquid mist with a specific spray radius or spray width.

[0027] The liquid supply device according to the invention is suitable for supplying a liquid to the nozzle. The liquid supply device can be of many types. For example, the liquid can be supplied to the nozzle from a liquid container via a hose. Alternatively, a line continuously filled with a liquid, such as a water or other liquid line, can serve as the liquid supply device. The liquid can be adapted to environmental properties. This means that a different liquid is used in warmer environments than in cooler environments. Other environmental properties can include open fire sources or areas with a risk of ignition, humidity in the air, or the like.Furthermore, the liquid is selected according to its heat capacity and enthalpy of vaporization, with liquids with higher heat capacity and enthalpy of vaporization being preferred, as their cooling effect is higher than that of air as the ambient medium of the heat sink.

[0028] The air flow generation device according to the invention generates an air flow, preferably outside air, in the direction of the heat sink, so that the heat sink is surrounded by an air flow. The constant air flow and the resulting displacement of air already heated by the heat sink improve the cooling performance of the cooling system.

[0029] The actuator according to the invention can be implemented as a valve arranged in the nozzle or the liquid supply device. The actuator serves to enable a liquid flow from the nozzle. In the exemplary case of a valve in the nozzle, the valve opens in response to a trigger signal sent by a controller, so that the nozzle supplied with liquid from the liquid supply device releases the liquid flow as a liquid mist. In the exemplary case of a valve in the liquid supply device, the liquid flow to the nozzle is released when the valve is opened.

[0030] Furthermore, the liquid mist generated by the nozzle is introduced into the air flow generated by the air flow generation device. This means that in this aspect, in addition to the improved cooling performance of the air flow, a liquid mist is also introduced into the air flow through the nozzle, whereby the cooling performance of the cooling system is further improved, on the one hand, by the additional heat capacity of the liquid and, on the other hand, by the evaporation enthalpy during a phase change of the liquid in the liquid mist from liquid to gaseous.

[0031] A further aspect of the invention shows an inverter with electrical and electronic components, in particular power electronics, and a cooling system according to the invention or an embodiment according to the invention as described above.

[0032] An inverter is conventionally equipped with both electrical and electronic components, and in particular power electronics, which generate a lot of heat. The inverter according to the invention also has these components and additionally a cooling system according to the invention, whereby it is possible for the heat-generating electrical and electronic components to be cooled by the cooling system during normal operation. During operation in which heat-generating components generate more heat than during normal operation, the trigger signal from the controller, which can be provided both as an individual component and as a function in a controller of the inverter, can provide additional cooling by opening the nozzle and thus enabling the fluid or liquid to flow out, spray, or atomize.

[0033] According to one embodiment, the power electronics is in heat-transferring contact with the heat sink.

[0034] Although indirect heat transfer between the power electronics and the heat sink may be sufficient, direct heat transfer between the power electronics and the heat sink is more efficient at dissipating heat from the power electronics. For this purpose, the heat sink can be shaped to match the power electronics.

[0035] One aspect of the invention shows a method for operating an inverter according to one of the preceding embodiments with the steps Providing an overcurrent through the power electronics, and Detecting the temperature of the power electronics and the heat sink.

[0036] The method is particularly characterized by the fact that when the detected temperature of the power electronics or the heat sink exceeds a temperature threshold, the controller provides the trigger signal for the actuator to open the nozzle.

[0037] In this aspect of the invention, an example is shown of when additional cooling is provided by the cooling system according to the invention. In particular, additional cooling is provided by the cooling system according to the invention when the temperature of the power electronics, the heat sink, or the heat sink exceeds a temperature threshold. This threshold is set arbitrarily before the inverter is operated and, in order to avoid damage to components, is sensibly based on the maximum permissible temperature of the components to be cooled. Alternatively, the threshold can also be based on a maximum temperature that the components to be cooled may have in order to provide an overcurrent. For this purpose, the controller can query the temperature of the power electronics, the heat sink, or the heat sink via a sensor.and then, when the temperature threshold is exceeded, send the trigger signal to the actuator.

[0038] According to one embodiment of the method according to the invention, the nozzle of the cooling system is further opened due to the provision of an overflow.

[0039] In this embodiment, an example of a special and excessively heat-generating operation of the power electronics is the provision of an overcurrent, in which additional cooling by the cooling system according to the invention is useful.

[0040] According to one embodiment of the method according to the invention, the nozzle of the cooling system is further opened due to a predicted provision of an overcurrent, wherein the prediction of the provision of the overcurrent is achieved by monitoring a power supply network connected to the inverter and detecting an anomaly in the power supply network.

[0041] In this embodiment, too, the cooling system is activated with increased cooling capacity due to an overcurrent. However, unlike the previous embodiment, the overcurrent has not yet been provided, but is predicted. In this case, "predicted" means that the power grid connected to the inverter is monitored for irregularities or anomalies by the controller or another device. If, for example, this monitoring detects that the grid frequency or voltage is dropping, the inverter can generate an overcurrent. In this case, the trigger signal can be sent while the power grid is being monitored but before the overcurrent is triggered, so that the fluid or liquid mist is already present on the heat sink.If the provision of an overcurrent is now ordered, the increased cooling capacity is provided by the cooling system even before the temperature of the components increases, so that the temperature of the components is permanently low.

[0042] It should be noted that the spraying of the fluid or liquid takes the form of a burst of spray. The burst of spray has a specific duration, and after the specific duration has elapsed, the spraying is stopped by closing the nozzle using the actuator. Although it goes without saying, it should be mentioned at this point that the actuator of each of the aforementioned aspects and embodiments of the invention is also suitable for closing the nozzle. The spraying duration can be influenced by one or more influencing factors, wherein the influencing factors include, for example, local conditions at the installation location of the system, in particular outside temperature, air pressure, altitude above sea level and / or air humidity, standard requirements, in particular the requirement for the frequency of providing excess current, the heat capacity of the fluid used, exceeding the temperature threshold, or the stability of the local energy supply network or.the frequency of events requiring an overcurrent. Furthermore, a maximum spray time can be specified, which particularly takes into account the inertia of the temperature reduction by the cooling system according to the invention. The maximum spray time is intended to prevent the spray duration from assuming enormous proportions due to the delay between the spray burst and the temperature reduction on the components to be cooled. For example, the maximum spray time can be between one and ten seconds.

[0043] In the following, the invention is illustrated with the aid of the figures, where Fig. 1 shows a cooling system according to one aspect of the invention, Fig. 2 shows an inverter according to the invention with a cooling system, and Fig. 3 shows an inverter according to the invention with a cooling system according to another embodiment.

[0044] The figures are explained in detail below.

[0045] For the sake of clarity and simplicity, the present invention is described in Fig. 1 is described with reference to the cooling system according to one aspect of the invention, in which a liquid supply device is installed. In Fig. 1 shows a cooling system 1 according to the invention. The cooling system 1 comprises a heat sink 2, a heat sink 3, a nozzle 4, a liquid supply device 5, and a controller 6. The heat sink 2 and the heat sink 3 are arranged next to one another in such a way that a heat-transfer connection is present. This means that the heat sink 2 can transfer its heat to the heat sink 3 as efficiently as possible. The nozzle 4 is designed as a mist nozzle. This means that the nozzle 4 discharges a liquid flowing through it as a liquid mist at an open end. Furthermore, the nozzle 4 is aligned such that an emerging liquid mist is sprayed onto the heat sink 3. The liquid supplied to the nozzle 4 is supplied to the nozzle 4 via the liquid supply device 5. By way of example, the liquid supply device 5 is Fig. 1 as a faucet with a water pipe. In order for the nozzle 4 to spray a liquid mist onto the heat sink 3, the actuator, which is Fig. 1 as a valve integrated with the nozzle 4, opening the nozzle 4. This occurs when the actuator receives a trigger signal from the controller 6. For example, the controller 6 sends a trigger signal to the actuator of the nozzle 4 when the controller 6 detects that the temperature of the heat sink 2 exceeds a temperature threshold. For this purpose, a sensor (not shown) is installed in the heat sink 2, whereby the sensor is connected to the controller 6 and the controller 6 can query temperature information from the sensor. In Fig. 1 shows, by way of example, that the controller 6 has a data connection to a sensor on the heat sink 2. However, it is also possible for the controller 6 to access a heat sensor on the heat sink 3.

[0046] Fig. Figure 2 shows an inverter 10 with a cooling system according to the invention. The inverter 10 has a housing 11 in which power electronics 12 are installed. The power electronics 12 are in heat-transferring contact with the heat sink 2, which in turn transfers its heat to the heat sink 3. The remaining configurations of the cooling system are similar to those of the cooling system of Fig. 1 identical.

[0047] In Fig. Figure 3 shows an inverter according to the invention with a cooling system according to a further embodiment. For the sake of clarity, redundant descriptions are omitted. Fig. The inverter 10 shown in Figure 3 differs from the one shown in Fig. 2 is that, in addition to cooling by an ambient air flow and the liquid mist sprayed onto the heat sink 3 through the nozzle 4, an air flow generating device 13 is provided. The air flow generating device 13 generates an air flow in the direction of the heat sink 3. The liquid mist generated by the nozzle 4 is sprayed into the air flow generated by the air flow generating device 13 in the direction of the heat sink 3 when additional cooling power is required. Fig. 3 also shows the power supply network 14, which is connected to the controller 6. The controller 6 can detect anomalies in the power supply network 14 via this connection, so that the trigger signal from the controller 6 to call up additional cooling power is provided before, for example, an overcurrent is or must be provided by the power electronics 12. List of reference symbols 1 cooling system 2 heat sink 3 heat sinks 4 nozzles 5 Liquid supply device 6 Control 10 inverters 11 housings 12 Power electronics 13 Air flow generation device 14 Energy supply network

Claims

[1] Cooling system (1) suitable for use with an electronic device with a heat sink (2), a heat sink (3) which is in heat-transferring contact with the heat sink, a nozzle (4), a fluid supply device (5) which supplies a fluid to the nozzle (4), and an actuator, characterized by , that the actuator is configured to open the nozzle (4) in response to a trigger signal from a controller (6) so that the nozzle (4) sprays the fluid in the direction of the heat sink (3). [2] Cooling system according to claim 1, wherein the fluid supply device (5) comprises a fluid container which has an internal pressure which is higher than the ambient pressure. [3] Cooling system according to claim 1, wherein the fluid supply device (5) comprises a conduit connectable to a fluid source. [4] Cooling system according to one of the preceding claims, wherein the fluid supplied to the nozzle (4) is a liquid. [5] Cooling system suitable for use with an electronic device with a heat sink (2), a heat sink (3) which is in heat-transferring contact with the heat sink (2), a nozzle (4) which is arranged to generate a liquid mist, and a liquid supply device (5) which supplies a liquid to the nozzle (4), characterized by an air flow generating device (13) which generates an air flow such that the heat sink (3) is surrounded by the air flow, and an actuator configured to open the nozzle (4) in response to a trigger signal from a controller (6) so that the nozzle introduces the liquid mist into the air stream. [6] Inverter (10) with electrical and electronic components and a cooling system (1) according to one of the preceding claims. [7] Inverter (10) according to the preceding claim, wherein the power electronics (12) is in heat-transferring contact with the heat sink (2). [8] Method for operating an inverter according to one of claims 6 and 7, comprising the steps Providing an overcurrent through the power electronics, and Detecting the temperature of the power electronics (12) and the heat sink (3), characterized by a If the detected temperature of the power electronics (12) or the heat sink (3) exceeds a temperature threshold, providing the trigger signal by the controller (6) for the actuator to open the nozzle (4). [9] The method according to claim 8, further comprising opening the nozzle (4) of the cooling system (1) due to the provision of the overflow. [10] Method according to claim 8, furthermore, due to a predicted provision of an overcurrent, the nozzle (4) of the cooling system (1) is opened, wherein the prediction of the provision of the overcurrent is achieved by monitoring a power supply network (14) connected to the inverter (10) and detecting an anomaly in the power supply network (14).

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