DE202012008740U1 - Thermosyphon with two capacitors in parallel - Google Patents

Abstract

Cooling system (1, 1 '), comprising a primary cooling stream (3, 3') for cooling a secondary cooling circuit (18) via a first heat exchanger (15, 15 '), wherein the secondary cooling circuit (18) as a thermosiphon cooling circuit in the form of a closed loop is formed, wherein the secondary cooling circuit (18) at least one evaporator (6) for receiving waste heat at least one of the evaporator (6) thermally connectable power electronic element (4), and wherein the secondary cooling circuit (18) one with the heat exchanger (15, 15 ' ) connected first capacitor (14) for transmitting at least a portion of the absorbed waste heat to the primary cooling stream (3, 3 '), characterized in that the secondary cooling circuit (18) connected to a second heat exchanger (17, 17') second capacitor ( 16), wherein the second heat exchanger (17, 17 ') is thermally dimensioned such that it is at least partially redundant to the first heat exchanger (15, 15 ') is, and wherein the first heat exchanger (15, 15') during operation of the cooling system (1, 1 ') is detachably connected to the secondary cooling circuit (18) such that the first heat exchanger (15, 15' ) is interchangeable without interruption of service.

Description

TECHNICAL AREA

The invention relates to the field of heat dissipation of power electronics from a converter, in particular by means of a thermosiphon cooling circuit.

STATE OF THE ART

Electrical and electronic elements of the power electronics are often as semiconductor elements, for example, IGBT's, thyristors, diodes, resistors, MOSFETs, as well as combinations of such devices and the like to understand. The term power electronics hereinafter means elements which typically have a blocking voltage of more than 500 volts during operation. These electrical and electronic elements must be cooled during operation of an inverter, as they also generate very high heat flows due to the very high power densities, which must be dissipated efficiently. In modern converters, these power electronic elements are often grouped together in power modules. For example, an inverter may be used to power an industrial mill, a vehicle, a ship, and / or generally for voltage conversion or voltage conversion.

If the heat is not removed from the semiconductor elements, they can be damaged, which in extreme cases may result in an inverter operator having to accept service interruptions due to repairs. Such interruptions in operation must be avoided, since they can lead to considerable economic disadvantages for the converter operator.

As inverter power density increases as the inverter increases in size, the demand for compact yet more powerful cooling systems increases. The heat dissipation of the heat flows of the power electronics from a converter is carried out in the operation of the inverter typically either via a connected to the inverter cooling water flow or a cooling air flow.

A cooling water flow is usually a cooling circuit with so-called service water. The disadvantage of such cooling water circuits is that the water tends to rot. The term "rotten" is understood to mean the structure of sediments and deposits on the surface of a heat exchanger, which hinders heat transfer.

The fouling also affects the cooling flow through the heat exchanger and contributes to the undesirable increase in pressure drop across the heat exchanger.

By contrast, the air from cooling air systems is often so polluted that it contributes to the unwanted clogging of a heat exchanger.

In both cases of cooling systems, this leads to a reduction in the performance of the cooling system, which ultimately means that the inverter must be temporarily put out of order for cleaning.

The object of the invention is therefore to provide an improved cooling system with which the operating interruptions of the inverter are at least reduced.

PRESENTATION OF THE INVENTION

This object is achieved by a cooling system according to claim 1.

This cooling system includes a primary cooling flow for cooling a secondary cooling circuit via a first heat exchanger. The secondary cooling circuit is designed as a thermosiphon cooling circuit in the form of a closed loop (loop-type thermosiphon). The secondary cooling circuit has at least one evaporator for receiving waste heat of at least one thermoelectrically connectable to the evaporator power electronic element. The secondary cooling circuit further comprises a first capacitor connected to the heat exchanger for transmitting at least a portion of the absorbed waste heat to the primary cooling flow. In addition, the secondary cooling circuit has a second condenser connected to a second heat exchanger, wherein the second heat exchanger is thermally dimensioned such that it is at least partially redundant to the first heat exchanger. During operation of the cooling system, the first heat exchanger is detachably connected to the secondary cooling circuit in such a way that the first heat exchanger without interruption of operation is against another heat exchanger of the type of the first heat exchanger. The removed from the inverter heat exchanger can then be conveniently examined outside the inverter, cleaned and / or repaired, so that its functionality is restored.

An advantage of the at least partial redundancy of the first capacitor by the second capacitor is that a converter equipped with the cooling system according to the invention does not shut down when the first capacitor or the first heat exchanger is replaced must be, but at least can be operated in partial load operation, so that an operator can avoid the disadvantages associated with a complete stoppage of an inverter. The term partial load operation is understood to mean operation with reduced power of the converter.

Since thermosiphon cooling circuits in operation have a working fluid that is at least partially in the vapor state, another advantage is that the loop of the secondary circuit despite an operation or partial operation of the power electronics elements to the outside must not be opened, so that no interruption in the heat dissipation occurs and so that the working fluid does not come into contact with the ambient air.

Another advantage of the redundancy provided by the second heat exchanger is that both the first and the second heat exchangers can be thermally dimensioned such that they are only sufficient for the nominal operation of the converter. Such a dimensioning means that the heat exchangers each have a correspondingly low volume requirement in terms of dimensions and are therefore particularly suitable for compact converter solutions.

In known solutions, the heat exchanger was conventionally oversized in such a way that it could still ensure a certain Mindestwärmeübetragung even after several years of operation to avoid performance losses in the heat transfer in the heat exchanger due to clogging (air cooling) or fouling in a liquid cooling.

Compared to conventional solutions can be kept smaller with a solution according to the present inventive concept, the total volume of the two heat exchangers, as the construction volume of an oversized heat exchanger conventional design.

There are cooling systems can be realized, in which the second heat exchanger is thermally dimensioned such that it is completely redundant to the first heat exchanger. For example, complete redundancy allows the converter to continue operating at full load during which one of the capacitors can be replaced.

Depending on the embodiment, the second condenser or the second heat exchanger may be different from the first condenser or the first heat exchanger. It is therefore possible that the second heat exchanger dimensionally larger, smaller and / or even poorer quality than the first heat exchanger is executed. However, this may still be sufficient if the first condenser or the first heat exchanger is designed to carry the main load of the waste heat removal of the power electronics elements, while the second heat exchanger must be designed only for a partial maintenance of the inverter operation during the replacement of the first heat exchanger.

Another advantage is that to achieve the desired redundancy not the whole power module, but. only one of the two or more capacitively associated capacitors must be replaced. The advantage lies in the fact that the capacitor to be exchanged or the heat exchanger contained in it is usually considerably less expensive than the power electronic elements and evaporators of the relevant power module.

This makes it clear that, depending on the replacement and maintenance concept of the converter and / or the cooling system, the condenser or heat exchanger units can be completely or only partially associated with the power module that can be inserted and removed in the converter. Alternatively, the capacitor or heat exchanger units may be associated with the inverter and may not be in the power module that can be inserted and removed from the inverter.

Another advantage is that in the case of leakage of the first capacitor in the first heat exchanger, the secondary circuit does not have to be completely put out of operation, but at least a partial further operation of the connected to the secondary circuit power electronics can be ensured to a reduced extent, during the leaking first capacitor or the first heat exchanger by the operator of the inverter is interchangeable.

Although it is quite conceivable that heat exchangers can also be connected in series with one another, it is advantageous for embodiments with thermally redundant capacitors for replacement and maintenance if the second heat exchanger of the first heat exchanger is connected in parallel to the second heat exchanger between the at least one evaporator and the primary cooling flow is arranged.

Further, it may be advantageous if the secondary cooling circuit of the cooling system has a preselector, with which the at least one evaporator during operation of the cooling system via the first heat exchanger or via the heat exchanger with the primary cooling current thermally connectable is, so that in the operation of the inverter - at most under partial load - the path of the working fluid via a particular capacitor is pre-selectable. A preselection can be made, for example, from a spatially remote from the inverter control center, or made locally on the inverter depending on the customer. The preselection element may, for example, be a switch which effects a switch position for the working medium. Selection of the path of the working fluid over a particular condenser can add significantly to the safety of the inverter operation if maintenance personnel are clearly shown which condenser is no longer in the way of the working medium and therefore can be replaced.

Alternatively or in addition to the Vorwählelement the heat exchanger can also over

Depending on the embodiment of the cooling system, the condenser can be permanently or detachably connected to a cooling device to form a heat exchanger, so that only the condenser itself or the entire heat exchanger can be exchanged as a unit during replacement. If at least the first heat exchanger is connected to the secondary cooling circuit via first couplings, and both coupling parts of the first couplings when opening the first couplings are each self-closing, an exchange of the heat exchanger without emptying the primary cooling flow and / or the secondary cooling circuit can be made quickly and easily. Self-closing couplings are also known by the term "dry-break" couplings.

In one embodiment of the cooling system, at least the first heat exchanger is fluidically connected to the secondary cooling circuit via first couplings.

Depending on requirements, the space available and / or existing, suitable means for supplying the inverter and / or its line modules, the primary cooling circuit may be a liquid cooling flow. This liquid cooling stream can be a service water circuit (two-way circuit) or at least a one-way flow (not a circuit) with service water. Alternatively, the liquid cooling stream can also be produced with water added with inhibitors, an ester or an oil-containing cooling medium. Liquid cooling streams having a water content are often preferred for ease of handling oil-containing liquid cooling streams.

Otherwise, the primary cooling stream can also be formed by a gaseous cooling stream, for example or in particular by an air stream. Such primary cooling is preferred if a ventilation system, for example a fan battery, is already present in the environment of the converter and / or its line modules.

The abovementioned advantages of the cooling system according to the invention are accordingly transferred to a converter provided therewith, in which the at least one evaporator is thermally connected to at least one power electronic element.

In modern converters, several power electronic elements and several evaporators are often combined to form a power module. Depending on the embodiment, the power electronics elements and the evaporators are combined to form a stack (for example, a so-called "press-pack stack") in which the power electronics elements and the evaporators are arranged alternately in the direction of the stack, that is to say in alternating sequence.

BRIEF DESCRIPTION OF THE DRAWINGS

Hereinafter, several embodiments of the invention will be explained in detail with reference to the drawing. This shows purely schematically

1 a first embodiment of a cooling system with a liquid cooling flow of the primary cooling circuit and a thermosiphon cooling circuit as a secondary cooling circuit for cooling of at least one power electronic element, and

2 a second embodiment of a cooling system with a gaseous cooling stream of the primary cooling circuit and a thermosiphon cooling circuit as a secondary cooling circuit for cooling of at least one power electronic element.

The reference numerals used in the drawings and their meaning are listed in the list of reference numerals. Basically, the same parts are provided with the same reference numerals in the figures. The described embodiments are exemplary of the subject invention and have no limiting effect.

WAY FOR CARRYING OUT THE INVENTION

The 1 shows a first embodiment of a dotted illustrated inventive cooling system 1 in a converter 100 , This cooling system 1 has a primary cooling circuit 2 with a liquid cooling flow 3 on. The cooling system 1 serves to cool three power electronic elements 4 a power module 5 , The three Power electronics elements 4 are with multiple evaporators 6 to a pile 7 clamped together to form a press-pack stack. These are the evaporators 6 and the power electronic elements 4 arranged in alternating order in the stack. Each evaporator has a first cooling connection 10 and a second cooling port 11 on, which in each case via a first pipe system 12 and a second pipe system 13 with a first capacitor 14 a first heat exchanger 15 and a second capacitor 16 a second heat exchanger 17 are fluidically connected. To avoid an electrical short circuit between two adjacent evaporators, which are at different electrical potentials during operation of the power module or inverter, are the first pipe system 12 and the second pipe system 13 at least partially electrically insulating, while the working fluid of the secondary cooling circuit is electrically insulating.

In operation of the inverter 100 the heat dissipation of the heat flows of the power electronic elements takes place 4 from the inverter 100 in that in the evaporators 6 a working medium present in liquid form is evaporated and via the first cooling connection 10 a capacitor 14 . 16 selectively or both capacitors 14 . 16 is also supplied in vapor form. The capacitors 14 . 16 serve for the condensation of the working medium, which subsequently in liquid form via the second cooling connection 11 the respective evaporator 6 is recirculated from where the working fluid is re-cycled so that it has a secondary cooling circuit 18 form.

In the in 1 illustrated embodiment, all first cooling connections open 10 in the first pipe system 12 while all second cooling connections 11 in the second pipe system 13 lead.

The primary cooling circuit 2 has a fluid reservoir 19 which is preferably thermally connected to a cooling unit (not shown) and which via a supply line 20 and a return 21 over the first heat exchanger 15 and the second heat exchanger 17 with the secondary cooling circuit 18 thermally connected on the one hand thermally, on the other hand, however, is fluidically separated. Depending on the embodiment of the heat exchanger, these may have an internal, further cooling circuit with a further working medium if necessary. However, the symbol used in the figures for the heat exchanger should not be interpreted in the present disclosure as having in each case an internal, further cooling circuit. In any case, the supply line is used 20 for supplying a primary cooling stream 3 to the heat exchangers 15 . 17 , which with respect to the primary cooling flow 3 are connected in parallel.

In other words, the first heat exchanger 15 and the second heat exchanger 17 between the primary cooling circuit 2 and the secondary cooling circuit 18 arranged. Here is the first heat exchanger 15 parallel to the second heat exchanger 17 between the evaporators 6 and the primary cooling stream 3 of the primary cooling circuit 2 arranged.

In alternative embodiments not illustrated in the figures, the fluid reservoir does not belong to the inverter but only to its surroundings.

In the cooling system 1 according to 1 is the first heat exchanger 15 for receiving a heat flow from the first capacitor 14 via a first feed section 22 with the supply line 20 connected while the second heat exchanger 17 for receiving a heat flow from the second capacitor 16 via a second feed section 23 with the supply line 20 connected is. Next is the first heat exchanger 15 for delivering the heat flow from the first condenser 14 over a first return section 24 with the return 21 connected while the second heat exchanger 17 for delivering the heat flow from the second condenser 16 over a second return section 25 with the return 21 connected is.

The first first pipe system 12 Branches on the heat exchanger side, so that it is both the first capacitor 14 of the first heat exchanger 15 , as well as the second capacitor 16 of the second heat exchanger 17 fluidly binds. Also the second pipe system 13 Branches on the heat exchanger side, so that it is both the first capacitor 14 of the first heat exchanger 15 , as well as the second capacitor 16 of the second heat exchanger 17 fluidly binds.

To the first heat exchanger 15 or the second heat exchanger 17 from the inverter 100 To be able to remove without having to stop the operation of the inverter, the heat exchanger are in all connecting lines 15 . 17 , So in the heat exchanger side ends of the pipe systems 12 . 13 ; the feeding sections 22 . 23 ; and the return sections 24 . 25 with shut-off devices, for example in the form of self-closing couplings 26 . 26 ' in which, when opening (decoupling) of the coupling parts, both coupling ends automatically leak-free or at least closed leak-tight, arranged.

As the heat exchangers 15 . 17 both the power module 5 can be assigned to exchange the power module 5 at the inverter 100 with a release of the electrical connection (not shown) of the power electronic elements 4 and any mechanical holding means to the inverter only the self-closing clutches 26 between the heat exchangers 15 . 17 and the primary cooling circuit 2 be opened.

In the 2 illustrated embodiment of a cooling system 1' differs from the in 1 illustrated, the first embodiment of the cooling system 1 in that their primary cooling flow 3 ' not liquid, but gaseous. Below are therefore only the first cooling system 1 different features of the cooling system 1' described according to the second embodiment, as well as any different effects explained. Compared to the first embodiment of the cooling system 1 identical or equivalent elements are therefore provided with the same reference numerals.

Instead of a supply line 20 and a return 21 shows the second embodiment of the cooling system 1' only one supply line 20 for a gaseous primary cooling stream 3 ' on. The heat exchangers 15 ' . 17 ' are at least partially in the supply line 20 arranged so that the gaseous primary cooling stream 3 ' during operation of the inverter 100 ' successively through the first heat exchanger 15 ' and the second heat exchanger 17 ' is passed.

For generating the primary cooling flow 3 ' can the cooling system 1' a cooling air unit 30 with a fan 31 exhibit. In alternative embodiments not illustrated in the figures, the cooling air unit is included 30 not to the inverter, but only to its environment. In addition, the fan can 31 also outside the inverter 100 ' be arranged. It is also possible that the fan with respect to the primary cooling flow 3 ' downstream seen below the heat exchanger 15 ' . 17 ' can be arranged so that it has the primary cooling flow 3 ' through the supply line 20 sucks.

LIST OF REFERENCE NUMBERS

1, 1 '

cooling system

2

Primary cooling circuit

3, 3 '

Liquid cooling flow, primary cooling flow

4

Power electronics element

5

power module

6

Evaporator

7

stack

10

first cooling connection

11

second cooling connection

12

first pipe system

13

second pipe system

14

first capacitor

15, 15 '

first heat exchanger

16

second capacitor

17, 17 '

second heat exchanger

18

Secondary cooling circuit

19

fluid reservoir

20, 20 '

supply

21

return

22

first feed section

23

second feed section

24

first return section

25

second return section

26, 26 '

Shut-off / clutch

30

Cooling air unit

31

fan

100, 100 '

inverter

Claims (11)

Cooling system ( 1 . 1' ) comprising a primary cooling stream ( 3 . 3 ' ) for cooling a secondary cooling circuit ( 18 ) via a first heat exchanger ( 15 . 15 ' ), wherein the secondary cooling circuit ( 18 ) is designed as a thermosiphon cooling circuit in the form of a closed loop, wherein the secondary cooling circuit ( 18 ) at least one evaporator ( 6 ) for absorbing waste heat at least one of the evaporator ( 6 ) thermally connectable power electronic element ( 4 ), and wherein the secondary cooling circuit ( 18 ) one with the heat exchanger ( 15 . 15 ' ) connected first capacitor ( 14 ) for transmitting at least a portion of the absorbed waste heat to the primary cooling flow ( 3 . 3 ' ), characterized in that the secondary cooling circuit ( 18 ) one with a second heat exchanger ( 17 . 17 ' ) connected second capacitor ( 16 ), wherein the second heat exchanger ( 17 . 17 ' ) is thermally dimensioned such that it is at least partially redundant to the first heat exchanger ( 15 . 15 ' ), and wherein the first heat exchanger ( 15 . 15 ' ) during operation of the cooling system ( 1 . 1' ) detachable with the secondary cooling circuit ( 18 ), that the first heat exchanger ( 15 . 15 ' ) is interchangeable without interruption of service. Cooling system according to claim 1, characterized in that the second heat exchanger ( 17 . 17 ' ) is thermally dimensioned so that it is completely redundant to the first heat exchanger ( 15 . 15 ' ). Cooling system according to claim 1, characterized in that the first heat exchanger ( 15 . 15 ' ) parallel to the second heat exchanger ( 17 . 17 ' ) between the at least one evaporator ( 6 ) and the primary cooling stream ( 3 . 3 ' ) is arranged. Cooling system according to one of the preceding claims, characterized in that the secondary cooling circuit ( 18 ) has a preselection element with which the at least one evaporator ( 6 ) during operation of the cooling system ( 1 . 1' ) over the first heat exchanger ( 15 . 15 ' ) or via the second heat exchanger ( 17 . 17 ' ) with the primary cooling stream ( 3 . 3 ' ) is thermally connectable. Cooling system according to one of the preceding claims, characterized in that at least the first heat exchanger ( 15 . 15 ' ) with the secondary cooling circuit ( 18 ) via first couplings ( 26 ), wherein both coupling parts of the first couplings ( 26 ) when opening the first couplings ( 26 ) are each self-closing. Cooling system ( 1 ) according to one of the preceding claims, characterized in that the primary cooling flow ( 3 ) is a liquid cooling flow with a water content. Cooling system according to one of claims 1 to 5, characterized in that the primary cooling flow is a gaseous cooling flow, in particular an air flow. Cooling system according to one of claims 1 to 7, characterized in that the first heat exchanger with the primary cooling flow ( 3 . 3 ' ) via second couplings ( 26 ' ), wherein both coupling parts of the second couplings ( 26 ' ) when opening the second clutches ( 26 ' ) are each self-closing. Inverter ( 100 . 100 ' ), comprising a cooling system ( 1 . 1' ) according to one of the preceding claims, wherein the at least one evaporator ( 6 ) thermally with at least one power electronic element ( 4 ) connected is. Converter according to claim 9, characterized in that a plurality of power electronic elements ( 4 ) and several evaporators ( 6 ) to a power module ( 5 ) are summarized. Converter according to claim 10, characterized in that the power electronic elements ( 4 ) and the evaporators ( 6 ) are arranged such that they form a stack ( 7 ), in particular a stack ( 7 ), in which power electronic elements ( 4 ) and evaporators ( 6 ) are arranged in alternating order.

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