Method and apparatus for cooling a power electronic circuit arrangement, and use thereof

Abstract

The invention relates to a method for cooling a power electronic circuit arrangement (2-1) which is housed together with a coolant passage (3-1) in an electronic module (1), by means of a coolant flowing through the coolant passage (3-1) in a cooling circuit, wherein the method according to the invention comprises: providing a first coolant flow with a first flow rate (f1); splitting the first coolant flow into a second coolant flow with a second flow rate (f2) and a third coolant flow with a third flow rate (f3), wherein the second coolant flow is guided through the coolant passage (3-1), whereas the third coolant flow is guided past the coolant passage (3-1) via a bypass;and combining the second coolant flow and the third coolant flow into a fourth coolant flow, which is used in the cooling circuit to provide the first coolant flow, wherein the first flow rate (f1) is greater than a specified maximum permissible value (f2max) for the second flow rate (f2), and wherein the first coolant flow is split in such a way as to prevent the second flow rate (f2) from exceeding the maximum value (f2max). The invention further relates to a cooling device (10) and to the use of such a method or device on board a vehicle.

Description

[0001] The present invention relates to a method for cooling a power electronic circuit arrangement, in particular, for example, an inverter for supplying current to an electrical machine in a vehicle (e.g., an electric or hybrid vehicle). Furthermore, the invention relates to a corresponding cooling device and the use of such a method or device.

[0002] The technical starting point of the present invention is a cooling, known from the prior art, of a power electronic circuit arrangement formed in an electronic module (e.g., inverter or electrical energy storage device) by means of a coolant circulating in a cooling circuit (e.g., water, water-glycol mixture, etc.). In this case, a coolant flow is generated in the cooling circuit by means of a coolant pump, which is guided, among other things, through a coolant passage that is housed together with the power electronic circuit arrangement in the respective electronic module. Due to the thermal contact with the circuit arrangement, the coolant flowing through the coolant passage absorbs heat from the circuit arrangement. This heat can be released again by the coolant in the further course of the cooling circuit or a return of the coolant to the coolant pump, e.g., at a heat exchanger (cooler), be itto the ambient air, or alternatively, for example, to a coolant in a secondary cooling circuit.

[0003] The cooling performance achieved with such a known cooling system is influenced on the one hand by the geometric and material conditions or the resulting heat transfer resistance between the circuit arrangement (heat source) and the coolant (heat sink) in the cooling passage, and on the other hand by the temperature difference between the circuit arrangement and the coolant in the cooling passage.

[0004] In practice, in order to maintain such a required temperature difference, for example for a certain required cooling capacity, the coolant must therefore flow through the coolant passage at a certain minimum flow rate.

[0005] On the other hand, it is understood that in practice, for each cooling device in question, a suitable design for a constant "nominal flow rate" or, in the case of a variable flow rate, a suitable "maximum flow rate" is also appropriate for cost reasons (e.g., regarding the pump, lines, seals, coolant passage). Furthermore, for each specific cooling device design, there is ultimately a predetermined maximum flow rate up to which the coolant can be forced through the cooling passage (and all other sections of the cooling circuit) without the risk of leakage or damage.

[0006] If in a specific usage environment not only a (single) electronic module or the circuit arrangement located therein, but at least one further heat-generating component is to be cooled, e.g. another electronic module with another power electronic circuit arrangement, then, taking into account the above explanation on the "design of the flow rate" in the prior art, the problem arises that when cooling the several different components or electronic modules to be cooled in one and the same cooling circuit, which makes sense for cost reasons, there is generally no optimal common flow rate for all components.

[0007] Here is an example: Assuming that on board a vehicle that is equipped with an electric machine to drive the vehicle, not only an inverter (power electronic circuit arrangement) used to supply current to the electric machine is to be cooled, but at the same time also an electrical energy storage device (containing a battery cell arrangement) for supplying an electrical system or the inverter, optimal, e.g. constant flow rates of the coolant flow can differ from one another, for example 12 l / min for the inverter on the one hand and 16 l / min for the energy storage device on the other hand (the values ​​are to be understood purely as examples).

[0008] To avoid the expense of two separate cooling circuits, each with optimally dimensioned flow rates (12 l / min on the one hand, 16 l / min on the other), the electronic module containing the inverter could be designed so that it can also operate with a coolant flow rate of 16 l / min or can withstand such an increased flow rate. The two electronic modules (containing the inverter and energy storage device) can then advantageously be arranged one after the other in the course of one and the same cooling circuit, and their cooling passages can be flowed through at an identical flow rate of 16 l / min. However, this solution disadvantageously increases the cost of constructing the electronic module implementing the inverter.

[0009] It is therefore an object of the present invention, when cooling a power electronic circuit arrangement of the type mentioned at the outset, with a predetermined flow rate or maximum flow rate of the coolant, to avoid the problems explained above and thus in particular to provide cooling in which one or more further components can be cooled by means of the cooling circuit in question, even if a different flow rate of the coolant flow is desirable or necessary for these.

[0010] According to a first aspect of the invention, this object is achieved by a method according to claim 1. The dependent claims relate to advantageous embodiments and developments of the invention.

[0011] The method according to the invention for cooling a power electronic circuit arrangement, which is accommodated together with a coolant passage in an electronic module, by means of a coolant flowing through the coolant passage in a cooling circuit, comprises: - Providing a first coolant flow with a predetermined first flow rate (e.g. designed to cool an electrical energy storage device in a vehicle), - splitting the first coolant flow into a second coolant flow with a second flow rate (e.g. designed for cooling an inverter in the vehicle) and a third coolant flow with a third flow rate, wherein the second coolant flow is guided through the coolant passage of the electronic module (e.g. containing the inverter), whereas the third coolant flow is guided past the coolant passage via a bypass, and - Combining the second coolant flow and the third coolant flow downstream of the coolant passage and the bypass to form a fourth coolant flow, which is used in the cooling circuit to provide the first coolant flow (e.g. after it has been passed through a coolant passage of the electrical energy storage device), wherein the first flow rate (e.g. 16 l / min) is permanently or at least temporarily greater than a permissible maximum value (e.g. 12 l / min) predetermined for the second flow rate, and wherein the splitting of the first coolant flow is carried out in such a way that the second flow rate avoids exceeding the maximum value predetermined for the second flow rate.

[0012] The term “power electronic circuit arrangement” is to be interpreted broadly and, in the context of the invention, is intended to mean that a comparatively high electrical power is involved for electronic devices, which is, for example, generated, controlled, stored or consumed by the circuit arrangement during operation. This is generally the case, for example, when the circuit arrangement is intended for the generation, control, storage and / or use of electrical energy not purely for data processing, but rather this energy is used to supply “electrical consumers” (such as, for example, an electric machine for driving a vehicle). This primarily applies to devices whose power consumption during operation can assume values ​​of more than 100 W, in particular more than 1 kW.

[0013] With the invention, the cooling of the electronic module in question or the cooling circuit used anyway can be used in a particularly advantageous manner to cool at least one further heat-generating component.

[0014] Interesting applications of the invention arise, for example, in particular when the first flow rate is, permanently or at least temporarily, greater than 1.1 times, in particular 1.2 times, a permissible maximum value predetermined for the second flow rate (or a value of the second flow rate fixed during operation or a maximum value of the second flow rate provided during operation with a variable second flow rate).

[0015] In one embodiment of the invention, a liquid coolant is used (e.g. water, water-glycol mixture, etc.).

[0016] In one embodiment of the method according to the invention, it is provided that the first flow rate is fixed.

[0017] In the sense of the invention, a “fixed specification” means that the quantity in question is not subject to any variation over time, but has a constant value over time.

[0018] In another embodiment of the method according to the invention, the first flow rate is specified variably, ie this flow rate can also change over time, for example depending on a currently required cooling capacity of a component cooled with this flow rate.

[0019] In one embodiment, it is provided that by splitting the first coolant flow, the second flow rate is set to a setpoint value predetermined for the second flow rate.

[0020] In a first variant of this embodiment, which is advantageous in many applications, the setpoint value specified for the second flow rate is fixed and in this case can expediently correspond, for example, to the maximum value specified for the second flow rate.

[0021] Deviating from this, however, according to a second variant of this embodiment, it can also be provided that the setpoint provided for setting the second flow rate is specified variably, for example depending on a currently required cooling capacity.

[0022] In a further development of the aforementioned embodiment, ie with an adjustment of the second coolant flow to a setpoint value within the scope of the splitting of the first coolant flow, it is provided that the splitting of the first coolant flow comprises a regulation of the second flow rate to the setpoint value predetermined for this purpose.

[0023] In such a control system, for example, the setpoint specified for the second flow rate (e.g. fixed or variable) can be used as the reference variable, and an actual value of the second flow rate, detected by a sensor, for example, can be used as the controlled variable. Depending on a control deviation determined by a setpoint / actual value comparison, at least one valve position of at least one valve, in particular a proportional valve, can be set as the manipulated variable. This valve forms a component of a "branching device" for branching the first coolant flow or of a "combining device" for combining the second and third coolant flows and whose valve position quantitatively influences the splitting, i.e. for example determines a ratio between the values ​​of the second flow rate and the third flow rate.

[0024] The actual value of the second flow rate as the controlled variable can be recorded, for example, directly by measuring this value using a flow meter through which the second coolant flow flows.

[0025] As a rule, however, it is simpler to provide, for example, at least one pressure measurement by means of at least one pressure measuring sensor, for detecting the second flow rate as a controlled variable. The pressure sensor is arranged at a suitable point along the cooling circuit and measures the pressure of the coolant there. Under the premise of predetermined known flow resistances of the individual sections of the cooling circuit and thus in particular the flow resistances of the coolant passage and the bypass, a corresponding flow rate can be deduced from such a measured pressure in order to then control the aforementioned at least one valve (as a component of the "branching device" or the "combining device"), e.g. a proportional valve, accordingly (e.g. electrically) within the framework of the control.

[0026] In a further simplified embodiment, it is provided that the above-mentioned at least one valve (as a component of the “branching device” or the “combining device”) is a pressure-controlled valve which combines the functions of such a detection of the controlled variable by means of pressure measurement, control (e.g. proportional control), and adjustment of the manipulated variable (valve position).

[0027] In one embodiment, it is provided that the method further comprises cooling a further power electronic circuit arrangement, which is accommodated together with a further coolant passage in a further electronic module, by means of coolant flowing through the further coolant passage, in that the fourth coolant flow is guided through the further coolant passage of the further electronic module.

[0028] In one embodiment, it is provided that the splitting of the first coolant flow into the second coolant flow with the second flow rate and the third coolant flow with the third flow rate is carried out by means of a proportional valve, the valve position of which determines the splitting quantitatively or based on the ratio between the (set) values ​​of the second flow rate and the third flow rate, or by means of a pressure-controlled valve.

[0029] According to a further aspect of the invention, the object mentioned above is achieved by a device for carrying out a method of the type described here. Such a device comprises a cooling circuit - with a coolant pump for providing a first coolant flow with a predetermined first flow rate in a first section of the cooling circuit downstream of the coolant pump, - with a branching device having an inlet connected to the first section of the cooling circuit for supplying the first coolant flow to this inlet, and having two outlets leading to corresponding second and third branching sections of the cooling circuit for splitting the first coolant flow into a second coolant flow supplied to the second branching section at a second flow rate and a third coolant flow supplied to the third branching section at a third flow rate, wherein the second branching section includes a coolant passage of an electronic module, whereas the third branching section represents a bypass leading past this coolant passage, - with a combining device having two inlets connected to the second and third branching sections of the cooling circuit for supplying the second and third coolant flows to these inlets, and with an outlet leading to a fourth section of the cooling circuit for combining the second coolant flow and the third coolant flow downstream of the second and third branching sections to form a fourth coolant flow supplied to the fourth section of the cooling circuit, from which fourth coolant flow the coolant is provided for supplying the coolant pump when the first coolant flow is provided, wherein the cooling circuit is designed such that, by splitting the first coolant flow, the second flow rate is prevented from exceeding a maximum value predetermined for the second flow rate.

[0030] The embodiments and special configurations described here for the method according to the invention can, individually or in any combination, also be provided in an analogous manner as embodiments or special configurations of the device according to the invention, and vice versa.

[0031] In one embodiment, the cooling device according to the invention comprises means for controlling the coolant pump such that the first coolant flow is provided by the coolant pump at a fixed, predetermined first flow rate. Alternatively, means for controlling the coolant pump can be designed for a variable specification of the first flow rate, in particular, for example, for a temporary reduction of the first flow rate in the event of a temporarily reduced cooling power required for a coolant passage of another component to be cooled, arranged downstream of the electronic module in the cooling circuit and through which the first flow rate flows.

[0032] In one embodiment, the branching device and / or the combining device are designed such that by splitting the first coolant flow, the second flow rate is set to a setpoint value predetermined for the second flow rate.

[0033] In this case, the setpoint specified for the second flow rate can be fixed, for example, and correspond to the maximum value specified for the second flow rate. Alternatively, however, this setpoint can also be specified variably, for example, depending on the cooling capacity currently required for the circuit arrangement.

[0034] In one embodiment, the device comprises means for regulating the second flow rate to the predetermined setpoint when splitting the first coolant flow.

[0035] Such means for regulating the second flow rate can, for example, comprise at least one sensor by means of which a measured variable representative of the second flow rate is detected, which is then used as a reference variable within the framework of the control. Furthermore, the means for regulating the second flow rate can also comprise, for example, an electronic device for evaluating the measured variable detection and, based thereon, outputting a control signal by means of which, depending on the result of a setpoint / actual value comparison relating to the second flow rate, for example at least one valve position of at least one valve, in particular a proportional valve, is set, which forms a component of a "branching device" for branching the first coolant flow or of a "combining device" for combining the second and third coolant flows. (At least) one electrically controllable valve can thus be controlled using an electrical control signal.

[0036] It should be noted that if the first flow rate is known, either because it is specified as a constant or because it is known due to a measurement, a “measurement value for the third flow rate” could also be used as a “measurement value representative of the second flow rate” (since the second flow rate can be determined as the difference between the first and the third flow rate).

[0037] It should also be noted that, instead of a "flow rate sensor" (arranged in the second or third branching section), the at least one sensor can also represent a "pressure sensor" arranged at a suitable location for measuring the coolant pressure prevailing at the relevant location. Assuming predetermined known flow resistances, in particular of the coolant passage and the bypass, the respective flow rate can be determined, for example, from the pressure dropping at the coolant passage or at the bypass. In a related embodiment, the means for regulating the second flow rate comprise at least one pressure sensor along the second branching section (e.g., upstream and / or downstream of the cooling passage) and / or at least one pressure sensor along the third branching section (e.g., at the beginning and / or end of the bypass).

[0038] The means for regulating the second flow rate may, alternatively or in addition to at least one electrically controllable valve, also comprise, for example, at least one pressure-controlled valve (such as a so-called "pressure valve," "pressure control valve," "pressure relief valve," etc.), which is arranged in the region of the "branching device" or the "combining device" and is suitably controlled by one of the coolant pressures prevailing there. With one or more such valves, functions such as detecting a controlled variable (here: pressure(s) or pressure difference(s)), controlling (e.g., proportional control), and adjusting the manipulated variable(s) (valve positions) can be implemented "purely mechanically."

[0039] In an embodiment of the device which is advantageous in many cases, the flow resistance of the third branching section (containing the bypass) is smaller than the flow resistance of the second branching section (containing the coolant passage).

[0040] In one embodiment, the fourth section of the cooling circuit includes a further coolant passage, which is accommodated together with a further power electronic circuit arrangement in a further electronic module (e.g. electrical energy storage device) in order to simultaneously cool the further power electronic circuit arrangement by means of the device by means of coolant flowing through the further coolant passage.

[0041] In one embodiment, the branching device may comprise a pressure-controlled valve or a proportional valve, the valve position of which can be determined for quantitatively splitting the first coolant flow into the second coolant flow with the second flow rate and the third coolant flow with the third flow rate or for splitting the first coolant flow into the second coolant flow and the third coolant flow based on the ratio between the (set) values ​​of the second flow rate and the third flow rate.

[0042] According to a further aspect of the invention, the use of a method of the type described here and / or a device of the type described here is proposed for cooling a power electronic circuit arrangement constituting an inverter for supplying current to the electric machine in a vehicle equipped with an electric machine for driving the vehicle, in particular with the relevant coolant passage arranged as part of the second branching section. The fourth coolant flow provided downstream of the inverter after cooling the inverter can advantageously be used to cool another device (in particular in the course of the fourth section of the cooling circuit) for which a higher flow rate of the coolant is required or at least desirable, permanently or at least temporarily.

[0043] In a particularly advantageous embodiment in this regard, the use provides for cooling the inverter and the electrical energy storage device at the same time in a vehicle which is equipped with an electrical machine for driving the vehicle, a power electronic circuit arrangement in the form of an inverter for supplying current to the electrical machine, and a further power electronic circuit arrangement in the form of an electrical energy storage device for supplying power to the inverter, in particular with the inverter arranged in the second branching section and the electrical energy storage device in the fourth cooling circuit section (if a higher cooling flow rate is to be provided for the energy storage device than for the inverter, otherwise vice versa).

[0044] Within the scope of the invention, the vehicle can be, for example, a battery electric vehicle (BEV) or a hybrid electric vehicle (HEV). Such vehicles typically have both an inverter and an electrical energy storage device, which, according to the invention, can be cooled during operation by means of a single or common cooling circuit.

[0045] The inverter can, for example, have at least one circuit carrier, wherein, for example, a substrate made of a plate-shaped ceramic material, such as based on aluminum nitride (AIN) or, for example, based on aluminum oxide (Al2O3), is advantageous. If a conductor track arrangement is only provided on one of the two flat sides of the substrate, the other flat side of the substrate can, for example, be connected to a heat sink for the purpose of heat dissipation, e.g., glued to the heat sink or soldered to the heat sink via a metallic layer, for example. A cooling channel can run within such a heat sink, which represents the cooling passage of the electronic module provided within the scope of the invention. In particular, in the case of an inverter as a power electronic circuit arrangement, this can have power electronic components, such as, in particular, power semiconductor components such as diodes, transistors (e.g., MOS-FETs), thyristors, etc. In particular, for example,semiconductor components manufactured using SiC (silicon carbide) technology.

[0046] Within the scope of the invention, the electrical energy storage device can, in particular, comprise a plurality of rechargeable battery cells connected in parallel and / or series. The cells can, in particular, be electrochemical battery cells. Examples of this include lithium-ion cells based on mixed transition metal oxides of lithium. So-called high-energy cells can be cells based on lithium nickel cobalt manganese oxide (NCM), for example, and high-performance cells can be cells based on lithium titanate (LTO), lithium ferrophosphate (LFP), or even ultracapacitors, for example. Furthermore, the energy storage device can contain numerous other electronic components, such as controllable energy transfer units (e.g., DC / AC converters or DC / DC converters), sensors, control electronics (e.g., for balancing and battery management), and communication devices (e.g., data interfaces), etc.In one embodiment, the electrical energy storage device has an energy storage capacity of at least 20 kWh, in particular at least 40 kWh. For heat dissipation, at least one heat sink can be provided that is in thermal contact with the battery cells and / or other heat-generating components of the energy storage device. A cooling channel runs through the heat sink, which represents the cooling passage of the electronic module containing the electrical energy storage device, as provided within the scope of the invention.

[0047] The invention will be further described below using exemplary embodiments with reference to the accompanying drawings. They schematically depict: Fig. 1 a device for cooling a power electronic circuit arrangement according to a first embodiment, and Fig. 2 a device for cooling a power electronic circuit arrangement according to a further embodiment.

[0048] Fig. 1 shows a device 10 for carrying out a cooling method, by means of which, in the example shown, a first power electronic circuit arrangement 2-1 and a second power electronic circuit arrangement 2-2 are cooled during their operation on board a vehicle.

[0049] The first power electronic circuit arrangement 2-1 is accommodated together with a coolant passage 3-1, e.g. a cooling channel in a heat sink, in a first electronic module 1 (in a housing structure), and the second power electronic circuit arrangement 2-2 is accommodated together with a coolant passage 3-2, e.g. a cooling channel in a heat sink, in a second electronic module 2 (in a housing structure).

[0050] In the example shown, the vehicle is a battery electric vehicle (BEV) that is equipped with an electric machine (e.g. three-phase synchronous motor) for driving the vehicle, the power electronic circuit arrangement 2-1 for implementing an inverter for supplying current to the electric machine, and the power electronic circuit arrangement 2-2 for implementing an electrical energy storage device (“vehicle battery”) for supplying an electrical on-board network and thus also the inverter.

[0051] The cooling of the inverter and simultaneously of the electrical energy storage device is carried out by means of a coolant flowing through the coolant passages 3-1 and 3-2 in a cooling circuit (e.g. water-glycol mixture or the like).

[0052] In the cooling circuit of the cooling device 10, as shown in Fig. 1 clearly arranged: - a coolant pump 20 for providing a first coolant flow with a predetermined first flow rate f1 in a first section of the cooling circuit downstream of the coolant pump 20, - a branching device 30 having an inlet connected to the first section of the cooling circuit for supplying the first coolant flow to this inlet, and having two outlets leading to corresponding second and third branching sections of the cooling circuit for splitting the first coolant flow into a second coolant flow supplied to the second branching section at a second flow rate f2 and a third coolant flow supplied to the third branching section at a third flow rate f3, wherein the second branching section includes the coolant passage 3-1 of the first electronic module 1 (inverter) and the third branching section represents a bypass leading past the electronic module 1, - a combining device 40 having two inlets connected to the second and third branching sections of the cooling circuit for supplying the second and third coolant flows to these inlets, and having an outlet leading to a fourth section of the cooling circuit for combining the second coolant flow and the third coolant flow downstream of the second and third branching sections (coolant passage 3-1 and bypass) to form a fourth coolant flow with flow rate f4 supplied to the fourth section of the cooling circuit (the flow rate f4 is thus the same as the flow rate f1).

[0053] As from Fig. 1, the cooling passage 3-2 of the second electronic module 2 (electrical energy storage device) is arranged in the fourth section of the cooling circuit (downstream of the combining device 40) and thus flows through coolant at the flow rate f1 (=f4).

[0054] Finally, the fourth section of the cooling circuit is followed by a fifth section of the cooling circuit (downstream of the second electronic module 2, up to the coolant pump 20), which serves to return the coolant from the fourth coolant flow to the coolant pump 20 and in which, in the example shown, a cooler 50 (heat exchanger) is arranged in order to extract heat from the coolant at this point (and, for example, to release it to the ambient air). Deviating from the example of Fig. 1, such a cooler could also be arranged in a different section of the cooling circuit. In any case, the coolant ultimately supplied to the coolant pump 20 is provided from the fourth coolant flow when the first coolant flow is provided.

[0055] A very advantageous feature of the cooling device 10 in this example is that the cooling circuit is designed such that, by splitting the first coolant flow at the branching device 30, an exceeding of a maximum value f2max predetermined for the second flow rate f2 is avoided by the second flow rate f2.

[0056] According to a first application example, it is initially assumed that the first coolant flow is provided by the coolant pump 20 with a fixed (constant) first flow rate f1 of, for example, 16 l / m, whether the coolant pump 20 is designed accordingly for this purpose or that the cooling device has a control device (not shown) by means of which the coolant pump 20 is controlled accordingly.

[0057] Furthermore, it is assumed by way of example that the maximum value f2max specified for the second flow rate f2 is 12 l / min, whereby the first coolant passage 3-1 is to be flowed through with coolant at a likewise constant value of the second flow rate of f2 = f2max.

[0058] In this case, the branching device 30 and the combining device 40 could be implemented, for example, as a simple line branch or line junction, i.e., as (flow-suitably dimensioned) "Y-pieces," such that, taking into account the flow resistances of the first coolant passage 3-1 and the bypass, the first coolant flow is distributed in the appropriate ratio (here: 3:1) between the coolant passage 3-1 and the bypass. In the present numerical example, the following applies: f1=16I / min f2=12I / min f3=4I / min

[0059] Advantageously, by means of the cooling device 10, both the inverter (in the first electronic module 1) and the electrical energy storage device (in the second electronic module 2) can be cooled simultaneously with predetermined different flow rates (here: 12 l / min and 16 l / min) of the coolant in one and the same cooling circuit.

[0060] By splitting and recombining the first coolant flow, which is "purely designed / implemented from a fluidic perspective," the second flow rate f2 is adjusted to the setpoint specified for the second flow rate (here: f2max). In the context of the present application example, it is sufficient to dimension the ratio of the flow resistances of the second and third branching sections (containing the bypass and the coolant passage, respectively) accordingly.

[0061] According to a second application example, in a modification of the above first example, it is assumed that the first coolant passage 3-1 is to be flowed through with a variable second flow rate f2, for example depending on a determined current cooling requirement for the circuit arrangement in question (here: inverter in the electronic module 1).

[0062] In this case, the branching device 30 could be designed, for example, as an electrically controllable proportional directional control valve or comprise one to which the first coolant flow (with flow rate f1) is supplied on the inlet side and which, on the outlet side, branches this flow to the second and third coolant flow in currently desired dimensions (flow rates f2 and f3) depending on a supplied electrical control signal.

[0063] It should be noted that, alternatively or in addition to the arrangement of a controllable proportional directional control valve for forming the branching device 30, it is also possible to provide such a valve for forming the combining device 40. In this case, the second and third coolant flows would be supplied to the valve on the inlet side in the currently desired amounts (flow rates f2 and f3) depending on an applied electrical control signal and would be combined to form the fourth coolant flow on the outlet side.

[0064] If the first coolant flow is provided with a fixed (constant) first flow rate f1, the aforementioned proportional directional control valve could be controlled, for example, on the basis of a look-up table or the like stored in the relevant (e.g. electronic) control device, which links a currently desired flow rate f2 with a control signal suitable for this purpose.

[0065] Alternatively, the control signal can also be generated, for example, as a control variable within the framework of a closed-loop control system by a respective control device, which is supplied with, for example, a variably specified setpoint for the second flow rate f2 as a reference variable, and which uses, for example, a sensor-detected actual value of the second flow rate f2 as a controlled variable. One or more coolant pressures in the region of the second and / or third branching section, detected by at least one pressure sensor, are also suitable for determining an actual value usable for closed-loop control.

[0066] An advantage of such a control of the second flow rate f2 to its setpoint has the advantage of greater universality as far as the setting of the first flow rate f1 is concerned: If a control of the second flow rate f2 is provided, this can easily be combined with a variable setting of the first flow rate f1, whether the first flow rate f1 is set (without control) or controlled (with control to a variable setpoint for f1).

[0067] The first flow rate f1 could, for example, be varied depending on the current cooling requirement of the circuit arrangement in question (here: energy storage device in the electronic module 2) by correspondingly varying the control of the coolant pump 20, either by setting (without control), for example on the basis of a lookup table stored in the control device in question, or by controlling the first flow rate f1.

[0068] For the purpose of regulating the first flow rate f1 to a variably specified setpoint value, for example, a sensor-detected actual value of the first flow rate f1 in the first cooling circuit section, e.g. at the outlet of the coolant pump 20, can be used to generate a corresponding control signal for the coolant pump 20 on the basis of a control deviation determined by a setpoint / actual value comparison.

[0069] In order to determine an actual value that can be used to control the first flow rate f1, it is often also possible to measure the pressure of the coolant in the area of ​​the first cooling circuit section by means of a pressure sensor (as a measured variable representative of the first flow rate f1).

[0070] According to a third application example, it is assumed that the first coolant flow is to be provided with a variably predetermined first flow rate f1 within the range of, for example, 12-16 l / m (depending on the cooling requirement for the electronic module 2), and that the second coolant flow is to be provided with a fixed predetermined second flow rate f2 of, for example, 12 l / m (which again can correspond in particular to the maximum value f2max predetermined for the second flow rate f2).

[0071] In this case, the device 10 can in principle be designed and operated, for example, as already described in the above second application example (for variable flow rate f1), both with regard to the generation of a variable flow rate f1, with or without control, and with regard to the generation of the constant flow rate f2, wherein in this case a fixed (constant) setpoint is to be used for the control of f2.

[0072] Alternatively, however, it can also be provided in this case that the means for regulating the second flow rate f2 comprise at least one pressure-controlled valve as a component of the branching device 30 or the combining device 40, which combines the functions of detecting the controlled variable and, for example, proportional control with a corresponding adjustment of the manipulated variable (valve position).

[0073] In order to regulate the second flow rate f2 (to a constant setpoint) by means of at least one pressure-controlled valve, various design variants come into consideration.

[0074] One variant, for example, consists in using a "Y-piece" as the branching device 30 to implement the one inlet and the two outlets, but in which a normally closed proportional pressure valve is arranged on the one of the two outlet-side line branches or outlets that leads to the third branching section (bypass) in such a way that this valve begins to open when the coolant pressure corresponds to the setpoint value of the flow rate f2, and thus coolant of the first coolant flow entering the branching device 30 is partially diverted to the bypass, and the second flow rate f2 is regulated to its setpoint value independently of the first flow rate f1. In this case, a "Y-piece" can be used as the combining device 40 to implement the two inlets and the one outlet.In particular in this variant it is advantageous if the flow resistance of the third branching section (containing the bypass) is relatively small, e.g. smaller than the flow resistance of the second branching section (containing the coolant passage 3-1 bypass).

[0075] The aforementioned pressure valve is provided in the area of, or as a component of, the branching device 30 and thus, in a sense, regulates the inflow of coolant into the bypass. It should be noted again that, alternatively or additionally, it is also possible to provide such a valve to form the combining device 40 in order to indirectly regulate the inflow of coolant into the bypass by regulating the outflow of coolant in the area of ​​the combining device 40.

[0076] The cooling process carried out by means of the device 10 advantageously prevents the second flow rate f2 from exceeding the maximum value f2max specified for the second flow rate f2. Therefore, in the Fig. 1, an “unmodified” electronic module 1 can advantageously be used and cooled with an optimal flow rate f2, although the coolant pump 20 delivers a significantly higher flow rate f1, be it permanently or at least temporarily.

[0077] In the following description of a further exemplary embodiment, the same reference numerals are used for components with equivalent functions, each supplemented by a lowercase letter "a" to distinguish the embodiment. In this context, only the differences from the previously described exemplary embodiment will be discussed, and otherwise, explicit reference is hereby made to the description of this previous exemplary embodiment.

[0078] Fig. 2 shows a device 10a for carrying out a cooling process as already described for the example according to Fig. 1. In contrast to the example of Fig. 1, however, in the device 10a, a branching device 30a, a third branching passage (bypass), and a combining device 40a are not arranged outside the respective electronic module (here: electronic module 1), but are integrated into the respective electronic module.

[0079] Although in practice this results in a different result compared to the first example ( Fig. 1) a certain amount of effort is required to redesign the electronic module 1, this implementation variant of the invention advantageously requires no additional components outside the electronic module 1. List of reference symbols 1 first electronic module 2-1 inverters 3-1 first coolant passage 2 second electronic module 2-2 electrical energy storage device 3-2 second coolant passage 10 Cooling device 20 Coolant pump f1 first flow rate 30 branching device f2 second flow rate f3 third flow rate 40 Association facility f4 fourth flow rate 50 heat exchangers (coolers)

Claims

[1] Method for cooling a power electronic circuit arrangement (2-1) which is accommodated together with a coolant passage (3-1) in an electronic module (1) by means of a coolant flowing through the coolant passage (3-1) in a cooling circuit, the method comprising: - Providing a first coolant flow with a predetermined first flow rate (f1), - splitting the first coolant flow into a second coolant flow with a second flow rate (f2) and a third coolant flow with a third flow rate (f3), wherein the second coolant flow is guided through the coolant passage (3-1) of the electronic module (1), whereas the third coolant flow is guided past the coolant passage (3-1) via a bypass, and - Combining the second coolant flow and the third coolant flow downstream of the coolant passage (3-1) and the bypass to form a fourth coolant flow, which is used in the cooling circuit to provide the first coolant flow. The first flow rate (f1) is permanently or at least temporarily greater than a permissible maximum value (f2max) specified for the second flow rate (f2), and the splitting of the first coolant flow is carried out in such a way that the second flow rate (f2) prevents the maximum value (f2max) specified for the second flow rate (f2) from being exceeded. [2] Method according to claim 1, wherein the first flow rate (f1) is fixed. [3] Method according to one of the preceding claims, wherein by splitting the first coolant flow the second flow rate (f2) is set to a setpoint value predetermined for the second flow rate (f2). [4] Method according to claim 3, wherein the setpoint value predetermined for the second flow rate (f2) is fixed and corresponds to the maximum value (f2max) predetermined for the second flow rate (f2). [5] Method according to claim 3 or 4, wherein the splitting of the first coolant flow comprises regulating the second flow rate (f2) to the setpoint value predetermined therefor. [6] Method according to one of the preceding claims, further comprising cooling a further power electronic circuit arrangement (2-2), which is accommodated together with a further coolant passage (3-2) in a further electronic module (2), by means of coolant flowing through the further coolant passage (3-2), in that the fourth coolant flow is guided through the further coolant passage (3-2) of the further electronic module (2). [7] Method according to one of the preceding claims, wherein the splitting of the first coolant flow into the second coolant flow with the second flow rate (f2) and the third coolant flow with the third flow rate (f3) is carried out by means of a proportional valve, the valve position of which determines the splitting quantitatively or based on the ratio between the values ​​of the second flow rate (f2) and the third flow rate (f3), or by means of a pressure-controlled valve. [8] Device (10) for carrying out a method according to one of the preceding claims, comprising a cooling circuit - with a coolant pump (20) for providing a first coolant flow with a predetermined first flow rate (f1) in a first section of the cooling circuit downstream of the coolant pump 20, - with a branching device (30) having an inlet connected to the first section of the cooling circuit for supplying the first coolant flow to this inlet, and having two outlets leading to corresponding second and third branching sections of the cooling circuit for splitting the first coolant flow into a second coolant flow supplied to the second branching section at a second flow rate (f2) and a third coolant flow supplied to the third branching section at a third flow rate (f3), wherein the second branching section includes a coolant passage (3-1) of an electronic module (1), whereas the third branching section represents a bypass leading past this coolant passage (3-1), - with a combining device (40) having two inlets connected to the second and third branching sections of the cooling circuit for supplying the second and third coolant flows to these inlets, and with an outlet leading to a fourth section of the cooling circuit for combining the second coolant flow and the third coolant flow downstream of the second and third branching sections to form a fourth coolant flow supplied to the fourth section of the cooling circuit, from which fourth coolant flow the coolant is provided for supplying the coolant pump when the first coolant flow is provided, wherein the cooling circuit is designed such that, by splitting the first coolant flow, the second flow rate (f2) does not exceed a maximum value (f2max) predetermined for the second flow rate (f2). [9] Device (10) according to claim 8, comprising means for controlling the coolant pump (20) such that the first coolant flow is provided by the coolant pump (20) at a fixed, predetermined first flow rate (f1). [10] Device (10) according to one of claims 8 to 9, wherein the branching device (30) and / or the combining device (40) are designed such that by splitting the first coolant flow, the second flow rate (f2) is set to a setpoint value predetermined for the second flow rate (f2). [11] Device (10) according to claim 10, wherein the setpoint value predetermined for the second flow rate (f2) is fixed and corresponds to the maximum value (f2max) predetermined for the second flow rate (f2). [12] Device (10) according to claim 10 or 11, comprising means for regulating the second flow rate (f2) to the setpoint value predetermined for this purpose when splitting the first coolant flow. [13] Device (10) according to one of claims 8 to 12, wherein the fourth section of the cooling circuit includes a further coolant passage (3-2) which is accommodated together with a further power electronic circuit arrangement (2-2) in a further electronic module (2) in order to simultaneously cool the further power electronic circuit arrangement (2-2) by means of the device (10) by means of coolant flowing through the further coolant passage (3-2). [14] Device (10) according to one of claims 8 to 13, wherein the branching device (30) comprises a pressure-controlled valve or a proportional valve, the valve position of which can be determined for quantitatively splitting the first coolant flow into the second coolant flow with the second flow rate (f2) and the third coolant flow with the third flow rate (f3) or for splitting the first coolant flow into the second coolant flow and the third coolant flow based on the ratio between the values ​​of the second flow rate (f2) and the third flow rate (f3). [15] Use of a method according to one of claims 1 to 7 and / or a device (10) according to one of claims 8 to 14 to cool, in a vehicle equipped with an electric machine for driving the vehicle, a power electronic circuit arrangement (2-1) representing an inverter for supplying current to the electric machine. [16] Use of a method according to claim 7 and / or a device (10) according to claim 14, in order to cool the inverter and simultaneously the electrical energy storage device in a vehicle which is equipped with an electrical machine for driving the vehicle, a power electronic circuit arrangement (2-1) in the form of an inverter for supplying current to the electrical machine, and a further power electronic circuit arrangement (2-2) in the form of an electrical energy storage device for supplying power to the inverter.

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