Filter module for a power converter

Abstract

Filter module (10) for a power converter (12) for the electric drive of a motor vehicle, with an EMC filter (14) for reducing electrical interference at an input and / or output of the power converter (12) and a cooling device for cooling the EMC filter (14) wherein the cooling device has a cooling channel (16) for the passage of a coolant, wherein the cooling channel (16) thermally surrounds at least a partial component of the EMC filter (14) in a spiral direction by more than 360° characterized by the fact that a plurality of subcomponents are inserted in a substantially cylindrical housing, wherein the housing is inserted in a jacket (18), and wherein the cooling channel (16) is arranged between the housing and the jacket (18).

Description

[0001] The invention relates to a filter module with a cooled EMC filter, with the help of which electrical interference at an input and / or output of the power converter can at least be reduced.

[0002] From DE 10 2018 208 308 A1 it is known to use a liquid-cooled cooling device intended for power electronics of a pulse inverter of a motor vehicle also for cooling an EMC filter of the pulse inverter by thermally coupling a metallic heat sink of the cooling device to at least one coil module of the EMC filter via a thermal paste.

[0003] From DE 10 2021 118 760 A1 a filter module for pulse inverters for the electric drive of a motor vehicle is known, which has an EMC filter for reducing electrical interference at an input and / or output of the pulse inverter.

[0004] From DE 10 2021 209 640 A1 a cooling device is known which is flexibly inflatable with a cooling medium and which can conform to electronic component parts of a printed circuit board.

[0005] From DE 10 2022 209 558 A1 it is known to design an electrically conductive coil for an electrical filter of a converter arrangement for an electric machine of a motor vehicle as a pipe electrically and thermally connected to the electrical filter for the passage of a cooling fluid.

[0006] There is a constant need to improve the cooling of a power converter.

[0007] The purpose of the invention is to demonstrate measures that enable a well-cooled power converter.

[0008] The problem is solved according to the invention by a filter module with the features of claim 1 and a power converter with the features of claim 9. Preferred embodiments of the invention are specified in the dependent claims and the following description, each of which can individually or in combination represent an aspect of the invention.

[0009] One aspect of the invention relates to a filter module for a power converter, in particular a pulse inverter, for the electric drive of a motor vehicle, comprising an EMC filter for reducing electrical interference at an input and / or output of the power converter and a cooling device for cooling the EMC filter, wherein the cooling device has a cooling channel for the passage of a coolant, wherein the cooling channel thermally surrounds at least one component, in particular a ferrite core, in a spiral direction by more than 360°, wherein a plurality of components are inserted in a substantially cylindrical housing, wherein the housing is inserted in a sheath, in particular made of plastic, and wherein the cooling channel is arranged between the housing and the sheath.

[0010] If a motor vehicle is to be electrically powered, it is necessary to convert the direct current (DC) supplied by a traction battery into alternating current (AC) using a power converter, which can function as an inverter, particularly a pulse inverter. Similarly, mechanical energy, for example during braking, may need to be recuperated and (temporarily) stored as electrical energy in the traction battery. This requires converting the supplied AC into DC using a power converter, which can function as a converter. During the conversion of current between DC and AC, electrical disturbances can occur, which can originate within the power converter and / or outside of it.To at least reduce these electrical disturbances, a mains filter designed as an EMC filter is provided; however, this filter can heat up during operation and therefore requires cooling. Particularly in an electrically powered vehicle designed as a sports car or racing car, the high electrical drive power required for high-performance driving can lead to exceptionally high temperatures on the components of the associated power converter.

[0011] The cooling channel provided for cooling the EMC filter is not only located on one side of the EMC filter, but extends over more than the entire circumference of the component to be cooled. A circumferential direction is understood here to be an imaginary tangential path spanning along a circumferential angle in a plane perpendicular to the longest extent and / or longitudinal direction of the component to be cooled and / or the EMC filter to be cooled, without regard to whether the component or the EMC filter is cylindrical. For example, the component to be cooled or the entire EMC filter can be fully or partially immersed in the cooling channel, preferably in the longitudinal direction, so that an annular gap remains between the component to be cooled or the entire EMC filter on the one hand and an inner side of the cooling channel, through which the coolant flows.Especially if the EMC filter has a ferrite core as a component, the ferrite core can easily be almost completely immersed in the cooling channel through which the coolant flows. This allows the core to be surrounded by the cooling channel and, in particular, along its entire length and / or at its end faces. Since the cooling channel surrounds at least a component of the EMC filter across its entire circumference, cooling can be improved, resulting in a well-cooled power converter.

[0012] The EMC filter is designed to improve the electromagnetic compatibility (EMC) of the power converter. Electrical power converters, such as switched-mode inverters, especially pulse inverters, can generate electrical interference that can propagate via a DC connection to a connected power supply network, such as the high-voltage electrical system of an electric or hybrid vehicle. The EMC filter can eliminate or at least reduce such common-mode and differential-mode interference. Preferably, the EMC filter is designed to suppress electromagnetic interference in the frequency range between 150 kHz and 30 MHz. During the filtering of such interference, electrical energy is converted into heat energy, which can lead to heating of the EMC filter and / or a component thereof.

[0013] The component of the EMC filter can be, for example, a ferrite core. It is also possible for the EMC filter to consist solely of the ferrite core as the only component intended for interference suppression, or even to be entirely composed of the ferrite core. Preferably, the EMC filter is designed as an electrical circuit comprising several components. In particular, the EMC filter includes at least one capacitor. For example, the EMC filter includes a capacitor designated as an X-capacitor for attenuating differential-mode interference, which may be interference voltages between the supply lines, and / or a capacitor designated as a Y-capacitor for suppressing common-mode interference, which may be interference voltages occurring in phase on the live conductors and neutral conductor relative to earth or ground.Additionally or alternatively, the EMC filter can include an inductor, in particular a choke, which preferably has a magnetically effective core, wherein the inductor can in particular effect common-mode rejection. Preferably, common-mode terminals of the converter are connected to power supply terminals via the choke and to a ground terminal via the at least one capacitor.

[0014] The cooling system can include a coolant conveyed through the cooling channel, which absorbs heat generated in the EMC filter and dissipates it in a heat exchanger or radiator, in particular an air-cooled front radiator. The coolant can be, for example, water or oil. Preferably, the coolant is an electrically non-conductive dielectric fluid, which allows components immersed in the cooling channel to be cooled directly without risk of electrical short circuits. Suitable coolants, particularly anhydrous ones, are mentioned, for example, in WO 95 / 07323 A1. Preferably, the coolant has a high heat capacity of, for example, approximately 4.19 kJ / (kg K).

[0015] Thermal contact between the cooling channel and the component to be cooled can occur via the coolant if the component is immersed in the cooling channel, resulting in convective heat transfer between the component material and the cooling channel material. However, it is also possible to separate the coolant from the component. In this case, thermal contact is characterized by heat conduction between the component to be cooled and the cooling channel material, with the coolant within the cooling channel able to dissipate heat convectively. A thermally insulating air gap in the heat flow between the component to be cooled and the cooling channel is avoided. Preferably, the heat flow along the thermal contact is as short as possible and is characterized by materials with the lowest possible thermal resistance.

[0016] The cooling channel, similar to a coil spring, can surround the component to be cooled with several coils arranged sequentially along the component's length, resulting in a circumferential angle for the cooling channel multiplied by the number of coils. Particularly when the coolant flowing through the cooling channel has a high heat capacity, the coolant can be charged with a significant amount of heat and thus be heated more effectively. This can improve the cooling efficiency and / or cooling capacity of the cooling system.

[0017] Preferably, successive turns of the cooling channel run longitudinally along the component to be cooled, separated from each other by an air gap. This prevents heat flow from the warm end of the cooling channel to the cold end due to heat conduction effects between successive turns. A heat flow in the wrong direction on the outside of the cooling channel can thus be avoided or at least reduced.

[0018] Preferably, the housing is filled with a resin so that the heat from the components inside can be transferred to the housing by thermal conduction and dissipated there via the cooling channel. In this case, the outer casing, which acts as a thermal resistance, is avoided. Instead, the casing can protect the cooling channel, for example, against damage. The cooling channel can penetrate the casing with an inlet and an outlet to allow the coolant to flow through it. Additionally or alternatively, at least one component of the EMC filter is surrounded by a casing, with the cooling channel located between the component to be cooled and the casing.

[0019] In particular, the EMC filter comprises at least one capacitor as one of its components, wherein the capacitor is surrounded by the cooling channel. Preferably, the capacitor is designed as a wound component and can therefore be a substantially cylindrical body that can be easily surrounded by the cooling channel in a spiral shape.

[0020] Preferably, the EMC filter comprises at least one coil, in particular a choke, as one of its components, wherein the coil is surrounded by the cooling channel. The coil typically has a substantially cylindrical outer contour, which may be slightly spirally surrounded by the cooling channel.

[0021] Particularly preferably, the EMC filter comprises at least one electrical resistor as one of its components, wherein the resistor is surrounded by the cooling channel. Electrical resistors are generally cylindrical in shape, so that the resistor can easily be spirally surrounded by the cooling channel.

[0022] In particular, the cooling channel features multiple sub-channels connected in parallel and / or in series for cooling different components of the EMC filter. This allows each component of the EMC filter to be cooled separately. Specifically, several components can be surrounded by a single sub-channel in a spiral configuration.

[0023] Preferably, the cooling channel is thermally coupled to the component to be cooled via a thermally conductive adhesive, in particular a thermal paste. The adhesive can thus establish both a mechanical and a thermal connection. This increases the heat flow through the thermal contact between the cooling channel and the component to be cooled.

[0024] Another aspect concerns a power converter, in particular a pulse inverter, for the electric drive of a motor vehicle, with a filter module that can be designed and further developed as described above for reducing electrical interference at an input and / or output of the power converter, and a conveying element for pumping the coolant through the cooling system of the filter module. The conveying element can be designed, in particular, as a pump for pumping the coolant. Since the cooling channel surrounds at least a component of the EMC filter over its entire circumference, cooling can be improved, resulting in a well-cooled power converter.

[0025] The invention is explained below by way of example with reference to the accompanying drawings and preferred embodiments, wherein the features shown below can represent an aspect of the invention, either individually or in combination. The drawings show: Fig. 1 a schematic perspective detail view of a filter module, Fig. 2 a schematic perspective view of a power converter with the filter module made of Fig. 1 and Fig. 3 a schematic perspective view of the power converter from Fig. 2 with enclosed filter module.

[0026] The in Fig. The filter module 10 shown in Figure 1 is designed for a power converter 12 configured as a pulse inverter for the electric drive of a motor vehicle. The filter module 10 includes an EMC filter 14, which may, for example, have a ferrite core as a component. The EMC filter 14 may also include capacitors, coils, or resistors, which are preferably encased in resin in a common housing. The EMC filter 14 is spirally surrounded by a cooling channel 16, which thus surrounds the EMC filter 14 with a circumferential angle of considerably more than 360°. In the illustrated embodiment, the cooling channel 16 has ten turns, resulting in a circumferential angle of approximately 3600° for the cooling channel 16. The cooling channel 16 is thermally connected to the EMC filter 14 to dissipate the heat generated in the EMC filter 14 and to cool it. The cooling channel 16 can be accessed from one in Fig. The EMC filter 14 and the cooling channel 16 are surrounded by a partially enclosed casing 18, which protects them. Preferably, the casing 18 is designed to press the cooling channel 16 against the EMC filter 14 or a component thereof, thereby further improving heat transfer and cooling performance.

[0027] As in Fig. As shown in Figure 2, the filter module 10 can be provided on an outer surface of the power converter 12. An inlet and outlet section of the cooling channel 16 penetrating the casing 18 is thus easily accessible, allowing a pump to easily convey a coolant through the cooling channel 16 of the filter module 10.

[0028] As in Fig.As shown in Figure 3, the cooling channel 16 and the EMC filter 14 are well protected by the casing 18. In particular, damage to the cooling channel 16 and / or leakage from the cooling channel 16 can be prevented by the casing 18. Preferably, the casing 18 covers not only a radially outward-facing surface, but also end faces extending longitudinally along the EMC filter 14, which may lie in a common radial area with the cooling channel 16 and, in particular, may conform radially to the inside of the EMC filter.

Claims

[1] Filter module (10) for a power converter (12) for the electric drive of a motor vehicle, with an EMC filter (14) for reducing electrical interference at an input and / or output of the power converter (12) and a cooling device for cooling the EMC filter (14) wherein the cooling device has a cooling channel (16) for the passage of a coolant, wherein the cooling channel (16) thermally surrounds at least a partial component of the EMC filter (14) in a spiral direction by more than 360° characterized by , that a plurality of subcomponents are inserted in a substantially cylindrical housing, wherein the housing is inserted in a jacket (18), and wherein the cooling channel (16) is arranged between the housing and the jacket (18). [2] Filter module (10) according to claim 1, wherein the cooling channel (16) surrounds the component to be cooled in several turns arranged one after the other in the longitudinal direction of the component, resulting in a circumferential angle for the cooling channel (16) multiplied by the number of turns. [3] Filter module (10) according to claim 2, wherein subsequent turns of the cooling channel (16) run spaced apart from each other in the longitudinal direction of the component to be cooled. [4] Filter module (10) according to one of claims 1 to 3, wherein the EMC filter (14) has at least one capacitor as one of the subcomponents, wherein the capacitor is surrounded by the cooling channel (16). [5] Filter module (10) according to one of claims 1 to 4, wherein the EMC filter (14) has at least one coil as one of the subcomponents, the coil being surrounded by the cooling channel (16). [6] Filter module (10) according to one of claims 1 to 5, wherein the EMC filter (14) has at least one electrical resistance as one of the subcomponents, wherein the resistance is surrounded by the cooling channel (16). [7] Filter module (10) according to one of claims 1 to 6, wherein the cooling channel (16) has a plurality of parallel and / or series connected sub-channels for cooling different sub-components of the EMC filter (14). [8] Filter module (10) according to one of claims 1 to 7, wherein the cooling channel (16) is thermally coupled to the component to be cooled via a thermally conductive adhesive. [9] Power converter (12) for the electric drive of a motor vehicle, comprising a filter module (10) according to one of claims 1 to 8 for reducing electrical disturbances at an input and / or output of the power converter (12) and a conveying device for conveying the coolant through the cooling device of the filter module (10).

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