Pump, in particular submersible pump, having a heat sink for cooling power components

Abstract

The invention relates to a pump having an electric drive and an electronic controller for the open-loop / closed-loop controlling of the pump drive, wherein the electronic controller comprises at least one power component the dissipated heat of which is absorbed via at least one heat sink connected to the power component in a thermally conductive manner, characterised in that the heat sink comprises at least one latent heat store or is connected to same in a thermally conductive manner.

Description

[0001] 40572F

[0002] KSB SE & Co. KGaA 67227 Frankenthal

[0003] Description

[0004] Pump, especially submersible pump, with heat sink for cooling power components

[0005] The invention relates to a pump with an electric drive and an electronic control for controlling / regulating the pump drive, wherein the electronic control comprises at least one power component, the waste heat of which is absorbed via at least one heat-conducting heat sink connected to the power component.

[0006] Electronic control of pump drives utilizes power components that generate waste heat during normal operation. These power elements, such as the semiconductor switches of a frequency converter inverter, are typically integrated into module packages (e.g., IGBT modules). The resulting waste heat must be dissipated from the surface of the module package and from the pump's electronics housing. To optimize heat dissipation, a heat sink made of a thermally conductive material, particularly metal, is often mounted onto the power components or modules. The specific geometry of the heat sink, especially with cooling fins, increases the surface area for heat transfer.

[0007] The cooling capacity, i.e., the size and design of the heat sink, is dimensioned application-dependently with regard to the expected power consumption and heat generation in order to avoid increasing production costs. However, due to the tightly designed cooling capacity, overload situations with higher heat generation must be avoided, as prolonged thermal stress can lead to overheating.

[0008] The strain can damage the electronics. Larger heat sinks for rare overload situations are disproportionate to the additional costs and are often not even possible due to limited installation space.

[0009] For certain applications and functions, however, it would be desirable to be able to draw on higher performance temporarily. A special case is, for example, the execution of a self-cleaning procedure in a submersible or wastewater pump. Therefore, a solution is needed that minimizes the risk of thermal overload during short periods of higher power demand without requiring a larger heat sink.

[0010] This problem is solved by a pump according to the features of claim 1. Advantageous embodiments of the pump are the subject of the dependent claims.

[0011] According to the invention, for a pump of this type, it is proposed to extend the heat sink used for cooling a power component by at least one latent heat storage element, or to connect such a latent heat storage element to the heat sink in a thermally conductive manner. The integration of the latent heat storage element serves the purpose of implementing a kind of temporary boost function for the cooling capacity. During normal operation, the power component is to be cooled conventionally by the integrated heat sink. The heat sink consists of a thermally conductive material such as metal, in particular aluminum or copper, and may optionally also have a surface-enhancing structure with cooling fins or cooling ribs. The waste heat from the power component is dissipated to the ambient air and / or an adjacent wall, in particular a housing wall.The design and size of the heat sink are dimensioned so that the power component is adequately cooled by the heat sink during regular pump operation.

[0012] In contrast, the integrated or connected latent heat storage unit is only available as an emergency reserve if the conventional heat sink cannot ensure sufficient heat dissipation, for example in the event of an anomaly that impairs the cooling effect 3 40572F or a temporarily higher power requirement of the pump is needed to implement a special function, which entails a higher heat generation of the power component.

[0013] The latent heat storage system can absorb and store thermal energy through the phase transition, meaning that the increased waste heat is not only dissipated by the cooling element, but also additionally bound in the latent heat storage system.

[0014] The latent heat storage system comprises a suitable material that, due to its enthalpy of fusion, allows for a specific heat absorption capacity. Typically, such a latent heat storage system is made of a solid material. When the enthalpy of fusion is exceeded, the storage material changes phase from solid to liquid, thereby binding the applied heat energy within the storage system.

[0015] The pump is preferably a centrifugal pump, in particular a wastewater and / or submersible pump. Submersible pumps preferably have a vertical, and preferably encapsulated, design for the pump and drive unit. The design is intended for underwater installation and must be able to withstand high pressures. Such pumps can also be specifically designed for pumping aggressive fluids.

[0016] Due to the nature of the application, wastewater and / or submersible pumps may experience contamination and / or blockages, particularly of the impeller. The power component is preferably part of a frequency converter; in particular, the power component can be at least one semiconductor switch for implementing an inverter. The power component is especially preferred as a module with multiple components or semiconductor switches, e.g., an IGBT module, a SiC power module (consisting of silicon carbide semiconductors), or a GaN power module (consisting of gallium nitride semiconductors).

[0017] Preferably, the latent heat storage medium is integrated within the heat sink, in particular encapsulated and embedded within the heat sink. The PCM material is 4 40572F.

[0018] The phase change material (PCM) of the latent heat storage unit can be in direct contact with the power component, ensuring that the highest temperature is located directly at the latent heat storage unit. Preferably, at least one surface of the latent heat storage unit is in direct contact with the power component, while the remaining surfaces are surrounded by the material of the conventional heat sink.

[0019] Alternatively, the latent heat storage unit can also be fully encapsulated and embedded within the heat sink, with only indirect contact with the power component via the heat sink. In other words, the PCM material of the latent heat storage unit is preferably completely surrounded by the heat sink in this case. The power component is then directly and thermally connected to the heat sink over a larger area, thus improving heat dissipation to the heat sink.

[0020] Ideally, the enthalpy of fusion of the PCM material used in the latent heat storage system is matched to the expected heat loss of the power component during a defined overload situation of the pump drive (execution of the special function). In particular, such an overload situation is conceivable when the pump is activated to perform a so-called cleaning procedure. For such a cleaning procedure, the pump or pump drive requires more power for a short period compared to regular pump operation, which leads to increased heat generation at the power component. This increased heat generation at the power component preferably causes the enthalpy of fusion of the PCM material to be exceeded, so that the excess heat is absorbed in the latent heat storage system by the triggered phase change. During regular pump operation, the heat generation preferably remains below the enthalpy of fusion. 5 40572F

[0021] If the power consumption and heat generation subsequently decrease again, the heat energy bound in the latent heat storage can also be released again by reversing the state of matter and dissipated via the cooling sink.

[0022] According to an advantageous embodiment, a defined overload situation occurs when the pump is to perform a cleaning procedure. The pump is primarily used for conveying wastewater, so that during operation, contamination of the pump, especially the impeller, by adhering solid particles regularly occurs. This adhering contamination can lead to impaired pump operation with increased power consumption, and even impeller blockage. To avoid this problem, it can be advantageous to perform a cleaning procedure during which the impeller is specifically controlled to force the detachment of the adhering solid particles through defined impeller movements. In this context, for example, repeatedly changing the direction of rotation of the pump impeller is conceivable.Experience shows that a higher power consumption is required, at least temporarily, to carry out the cleaning procedure.

[0023] According to an advantageous embodiment, the heat sink is in thermally conductive contact with at least one wall of the pump or electronics housing. Particularly in wastewater pumps and / or submersible pumps, the pumped medium or a medium surrounding the pump can be used as a coolant, flowing around or through at least certain parts of the pump and thus enabling heat absorption by the pump housing or heat sink. It is also conceivable that the housing is air-cooled, for example, by being surrounded or permeated by a flow of cooling air. If an anomaly occurs, for example, caused by a blockage, the corresponding coolant flow (air or liquid) may be interrupted, so that the heat dissipation typically achievable with a conventional heat sink is no longer guaranteed.It may also be intended for such a purpose that the reduced cooling effect of the heat sink caused by the anomaly can be at least temporarily compensated for by the integrated latent heat storage. 6 40572F.

[0024] In a preferred embodiment, the pump can include a controller configured to temporarily operate the pump at a higher power consumption for the execution of a cleaning procedure. It is further preferred that the pump controller monitors the heat generation of the power component and / or the storage state of the latent heat storage device during the cleaning procedure. For example, if the additional storage capacity of the latent heat storage device is exhausted, this must be detected by the controller, and the pump's power consumption must be reduced again to prevent thermal damage to the pump. This can generally be ensured by measuring the temperature at the power module, in particular an IGBT module, SiC module, MOSFET module, or GaN module. However, it is also conceivable to measure the storage state or estimate the available heat storage capacity.

[0025] Preferably, the pump control system can include means for detecting a blockage in the pump. If, for example, a blockage is detected, the control system can automatically trigger a cleaning procedure, during which the heat generation at the power component and / or the condition of the latent heat storage system is monitored.

[0026] In addition to the pump according to the invention, the present invention relates, according to a second aspect, to a method for operating a pump. The pump comprises an electric drive and an electronic control unit for controlling / regulating the pump drive. The electronic control unit has at least one power component, the waste heat from which is absorbed by at least one heat sink thermally connected to the power component. According to the invention, it is proposed that the pump is temporarily driven by the control unit with increased power consumption, and that the higher heat output temporarily produced by the increased power consumption is absorbed by a latent heat storage device of the pump, in particular an integral latent heat storage device of the heat sink. 7 40572F

[0027] Preferably, during increased power consumption, the control system monitors the heat generation of the power component and / or the storage state of the latent heat storage and reduces the power consumption if the increased waste heat can no longer be absorbed by the latent heat storage.

[0028] Further advantages and features of the invention will be explained in more detail below with reference to exemplary embodiments shown in the figures. The figures show:

[0029] Figure 1: An embodiment of a conventional solution according to the state of the art

[0030] Technology,

[0031] Figure 2: a first embodiment of pump electronics according to the invention with a latent heat storage unit integrated into the heat sink, and

[0032] Figure 3: a second embodiment of pump electronics according to the invention with a latent heat storage unit integrated into the heat sink

[0033] The invention is described by way of example using a centrifugal pump with an integrated frequency converter. The centrifugal pump is designed as a submersible pump and / or serves to pump wastewater.

[0034] Figure 1 shows the conventional solution with a conventional heat sink for cooling the IGBT module of the installed inverter of the pump; Figures 2 and 3 show the solution according to the invention.

[0035] The pump and electronics housing 10 is shown schematically. It is sealed against the environment to prevent the ingress of liquid or pumped medium; that is, outside the housing 10 there is either ambient air, water, or the pumped medium 11. The sealed interior of the housing 10 contains air 12. 8 40572F

[0036] The electronics, i.e., the inverter for controlling the pump unit, are located within the housing 10. An example shown here is a single IGBT module 15 as a power component, although the power component can alternatively or additionally include a SiC module, a MOSFET module, and / or a GaN module. For the sake of simplicity, only an IGBT power module 15 will be considered in the following. An outer surface of the IGBT module 15 is thermally connected to a heat sink 16, in particular in the form of a thermally conductive material, e.g., a metallic heat sink. According to the embodiment of Figure 2, a PCM material (“phase change material”) 20 is embedded in a cavity of the heat sink 16 which is open to the IGBT module 15, and the PCM material 20 is directly connected to the outside of the IGBT module 15; the heat sink 16 is therefore only indirectly connected to the module 15.The PCM material 20 consists of a material with good thermal conductivity and is originally in a solid state, so that the waste heat emitted by the IGBT module 15 can be transferred via the PCM material 20 to the heat sink 16 and from there via the housing 10 to the external environment 11.

[0037] In the embodiment shown in Figure 3, the latent heat storage medium, or PCM material 20, is completely encapsulated and embedded within the heat sink 16; that is, the PCM material 20 is completely surrounded by the heat sink 16. The power component 15 is therefore only indirectly connected to the latent heat storage medium 20 via the heat sink 16. During normal pump operation, cooling preferably occurs only via the heat sink 16, with direct heat dissipation to the external environment via the housing 10.

[0038] However, if the pump is to be operated temporarily with a higher power consumption, which inevitably leads to increased heat generation, the additional heat absorption capacity of the PCM material 20 is available in the embodiments of the invention shown in Figures 2 and 3. If the temperature at the IGBT module exceeds the enthalpy of fusion of the PCM material 20, the PCM material 20 undergoes a phase change from the solid to the liquid state, with the associated heat storage. Thus, even during a temporary 9 40572F

[0039] Sufficient cooling of the IGBT module 15 must be ensured in overload situations.

[0040] The thermal energy temporarily stored in the PCM material 20 can be released via the heat sink 16, for example during pump shutdown or under load operation, causing the PCM material 20 to return to the solid state.

[0041] The proposed approach is particularly useful for submersible pumps whose electronics and cooling system are designed for regular pump operation. However, submersible pumps regularly experience contamination or blockages of the pump unit due to solid particles in the pumped medium. These particles, which adhere to the pump structure and especially to the impeller, can be removed using a special cleaning procedure. Such a cleaning procedure, however, requires a temporarily higher power consumption from the pump unit; the associated increased heat loss can be absorbed by the integral PCM material 20. For this purpose, it is advisable for the pump control system to monitor the temporary overload situation with higher power consumption and, in particular, to keep an eye on the storage status of the PCM material 20.For example, if the latent heat storage is saturated, the overload operation must be switched off to avoid thermal damage to the IGBT module 15.

Claims

10 40572F Patent claims Pump, especially submersible pump, with heat sink for cooling power components 1. Pump with an electric drive and an electronic control for controlling / regulating the pump drive, wherein the electronic control comprises at least one power component (15) whose waste heat is absorbed via at least one heat sink (16) thermally connected to the power component (15), characterized in that the heat sink (16) comprises at least one latent heat storage element (20) or is thermally connected to it.

2. Pump according to claim 1, characterized in that the at least one latent heat storage element (20) is encapsulated within the heat sink (16), preferably completely enclosed by the heat sink (16).

3. Pump according to one of the preceding claims, characterized in that the latent heat storage (20) forms a connection interface between the cooling element (16) and the power component (15).

4. Pump according to one of the preceding claims, characterized in that the enthalpy of fusion of the latent heat storage (20) is matched to the waste heat emitted by the power component (15) during a defined overload situation of the pump drive, in particular the execution of a cleaning procedure. 11 40572F 5. Pump according to one of the preceding claims, characterized in that the dimensioning of the heat sink (16) is selected such that sufficient heat dissipation via the heat sink (16) occurs during regular pump operation without phase change of the latent heat storage (20).

6. Pump according to one of the preceding claims, characterized in that the heat sink (16) is in thermally conductive contact with a wall of a pump or electronics housing (10), and the pump or electronics housing (10) is at least partially surrounded, in particular flowed around or washed around, by a cooling medium, preferably by a fluid, particularly preferably by the pumped medium (11).

7. Pump according to claim 6, characterized in that a phase change of the latent heat storage (20) can compensate for a reduced cooling effect of the heat sink (16) caused by an anomaly in the pump operation, wherein the reduced cooling effect is caused in particular by a blockage in the conveying medium line, which impairs the heat exchange between the heat sink (16) and the conveying medium (11).

8. Pump according to one of the preceding claims, characterized in that a control of the pump is configured to operate the pump temporarily with higher power consumption for the execution of a cleaning procedure.

9. Pump according to claim 8, characterized in that the control of the pump monitors the temperature development and / or the storage state of the latent heat storage (20) during the cleaning procedure and reduces the power consumption of the pump in the absence of storage capacity in order to avoid thermal damage to the pump.

10. Pump according to one of the preceding claims 8 or 9, characterized in that the control of the pump has means for detecting a blockage of the pump and a cleaning procedure after detection 12 40572F triggers a blockage with temporarily increased power consumption.

11. Pump according to one of the preceding claims, characterized in that the power component (15) is an IGBT module, a SiC module, a MOSFET module or a GaN module or comprises at least one of these modules and / or the power component (15) is part of a frequency converter for speed control of the pump.

12. Pump according to one of the preceding claims, characterized in that the pump is a submersible pump.

13. Method for operating a pump with an electric drive and an electronic control for controlling / regulating the pump drive, wherein the electronic control comprises at least one power component (15) whose waste heat is absorbed via at least one heat sink (16) thermally connected to the power component (15), characterized in that the pump is temporarily controlled by the control with increased power consumption and the higher heat output temporarily produced by the increased power consumption is absorbed by a latent heat storage device (20).

14. Method according to claim 13, characterized in that the control system monitors the heat generation and / or the storage state of the latent heat storage unit (20) during the increased power consumption and reduces the power consumption when the increased waste heat can no longer be absorbed by the latent heat storage unit (20).

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