Capacitance roll of intermediate circuit capacitor and intermediate circuit capacitor with common mode current derivation function

Abstract

A capacitor roll of an intermediate circuit capacitor having a first metallization layer serving as a positive potential and a second metallization layer serving as a negative potential, and having at least one region serving as a return path for a common mode current, and an intermediate circuit capacitor having a common mode current derivation function are provided, the capacitor roll having a first metallization layer serving as a positive potential and a second metallization layer serving as a negative potential, the region comes from at least one of the metallization layers and is formed electrically isolated therefrom.

Description

Technical Field

[0001] The present invention relates to the field of power electronic devices. Background Art

[0002] Power electronics systems are widely used worldwide, particularly in electric vehicle propulsion systems. One of the primary challenges facing these systems is the generation of electromagnetic pollution, including high-frequency interference. Undesirable high levels of electromagnetic interference generated by power electronics converters, such as inverters, can affect adjacent electronic systems and disrupt radio services. Therefore, this unwanted interference must be limited to a certain level.

[0003] The traditional approach to minimizing electromagnetic radiation is to use passive electromagnetic compatibility filters (EMC filters). EMC filters can be manufactured as modules and integrated into the inverter, commutation unit, or other components of the control board. For example, Y-type capacitors can be built into the DC link capacitor to improve thermal performance. Alternatively, magnetic cores can be used directly at the phase interface instead of conventional DC-side common-mode chokes. Integrating EMC filters into the inverter as separate components or EMC suppression components typically results in disadvantages, such as higher component and manufacturing costs, as well as increased size and weight.

[0004] EMC interference can occur asymmetrically (as differential mode) or symmetrically (as common mode). Common-mode interference is caused by semiconductor switching processes and propagates through all conductive elements of the drive system to one or more components with high stray capacitance, which provides a path for the common-mode interference to the chassis or ground. The common-mode interference then flows through the chassis to a point in the system where it returns to its source. The shorter this loop, the less likely these currents will affect the inverter's functionality, and the lower the EMC emissions. Summary of the Invention

[0005] Therefore, it is an object of the present invention to provide a device which can reduce common-mode interference.

[0006] This object is achieved by the features of the independent claim. Advantageous embodiments are the subject matter of the dependent claims.

[0007] A capacitor winding of an intermediate circuit capacitor is provided, comprising a first metallization layer serving as a positive potential and a second metallization layer serving as a negative potential, and comprising at least one region serving as a return path for a common-mode current, the region being formed from at least one of the metallization layers and being electrically isolated therefrom.

[0008] In one embodiment, it is provided that the region serving as return path for the common-mode current is electrically isolated from the remaining metallization layer by at least one continuous gap passing through the metallization layer.

[0009] In one embodiment, it is provided that the region serving as the return path for the common-mode current is arranged at the start region, end region or central region of the metallization layer.

[0010] In one embodiment, it is provided that the metallization layer is applied to the mutually facing sides of a single electrically insulating foil.In one embodiment, it is provided that a plurality of electrically insulating foils are provided and that the metallization layer is respectively applied to one side of one of the electrically insulating foils.

[0011] In one embodiment, it is provided that, in the case of only one region serving as a return path for the common-mode current, another metallization layer has a sub-region at a position below the region serving as a return path for the common-mode current, which sub-region is electrically isolated from the metallization layer, so that the sub-region is electrically connected to the metallization layer via only one connecting tab, or is electrically connected to the metallization layer via an external connecting element.

[0012] Furthermore, an intermediate circuit capacitor formed from a plurality of capacitor windings is provided.

[0013] In one embodiment, the number of capacitor windings having a region serving as a return path for the common-mode current in the metallization layer serving as a positive potential is equal to the number of capacitor windings having a region serving as a return path for the common-mode current in the metallization layer serving as a negative potential. In one embodiment, the number of capacitor windings having a region serving as a return path for the common-mode current in the metallization layer serving as a positive potential is smaller or greater than the number of capacitor windings having a region serving as a return path for the common-mode current in the metallization layer serving as a negative potential. In one embodiment, only capacitor windings having a region serving as a return path for the common-mode current in the metallization layer serving as a positive potential or only capacitor windings having a region serving as a return path for the common-mode current in the metallization layer serving as a negative potential are provided.

[0014] Furthermore, an electronics module is provided, which comprises an inverter and an intermediate circuit capacitor electrically connected to the inverter.

[0015] Furthermore, an at least partially electrically driven vehicle is provided, which has an electronics module, wherein each region of a capacitance winding of an intermediate circuit capacitor serving as a return path for a common-mode current is in contact with a component providing a ground.

[0016] In one embodiment, it is provided that the component providing the ground connection is the vehicle frame or a circuit board of an electronics module.

[0017] Other features and advantages of the present invention are apparent from the following description of exemplary embodiments of the present invention, the accompanying drawings showing details of the present invention, and the claims. In variants of the present invention, the individual features can be realized individually or in any combination. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Preferred embodiments of the present invention are explained in more detail with reference to the accompanying drawings.

[0019] Figure 1 A schematic diagram showing the structure of a capacitor coil according to one embodiment of the present invention.

[0020] Figure 2a 、 Figure 2b 、 Figure 3 and Figure 4 Schematic diagrams respectively showing alternative structures of a capacitor coil according to an embodiment of the present invention.

[0021] Figure 5 Two capacitor coils are shown, each having a structure according to an embodiment of the present invention.

[0022] In the following description of the figures, identical elements or functions are provided with the same reference symbols. DETAILED DESCRIPTION

[0023] Figure 2a 、 Figure 2b 、 Figure 3 and Figure 4 It is only drawn very schematically. It should be noted that in these figures, Figure 1 Again, the left region is significantly longer than the right region.

[0024] As mentioned at the outset, the present invention is primarily concerned with common-mode interference generated by semiconductor switching processes in power electronic converters (eg, inverters).

[0025] A device is proposed that short-circuits the common-mode current to ground or the vehicle frame near the main common-mode current source (the power semiconductor). This prevents the common-mode current from propagating over long distances. To achieve this, a design concept for adjusting the intermediate circuit capacitor, more specifically the structure of its individual capacitor windings, is proposed as described below.

[0026] A typical intermediate circuit capacitor for automotive applications consists of at least one capacitor coil 1 (hereinafter referred to as a coil), which is wound around a special rod (often called a mandrel). These coils are made from at least one metallized polyethylene foil with a special fuse pattern. These coils are then connected (welded or soldered) to a conductive element (busbar). The entire assembly is then placed in a housing and typically cast with a special material (potting compound).

[0027] The intermediate circuit capacitor typically has a plurality of windings 1. Each winding 1 has two metallization layers 10, 11 in a known manner, one of which serves as a positive potential and the other as a negative potential. The metallization layers 10, 11 are separated from one another (electrically insulated) by at least one electrically insulating foil 13. In one embodiment, the first metallization layer 10, 11 can be arranged on one side of the electrically insulating foil 13, and the second metallization layer 11, 10 on the other side of the foil 13. In this case, the first metallization layer ( Figure 1 An electrically insulating foil is placed on the first metallization layer 10 (in this case, the first metallization layer 10) to prevent it from coming into contact with the second metallization layer 11 during the rolling process. Alternatively, a separate electrically insulating foil 13 can be provided for each metallization layer 10 and 11. This means that only one side of each metallization layer 10 or 11 is provided. In this case, the foils 13 are placed one on top of the other and then rolled up. Of course, it should be noted that the metallization layers 10 and 11 do not come into electrical contact. This can be achieved by aligning the metallization layers 10 and 11 relative to each other or by introducing an additional electrically insulating foil.

[0028] Independent of the exact structure of the roll 1, according to the invention, at least one of the metallization layers 10, 11 is modified in such a way that its subregion is electrically isolated from the remaining metallization layers 10, 11. For this purpose, a gap 2 is introduced into the metallization layers 10, 11, which gap reaches the electrically insulating foil 13 to which the metallization layers 10, 11 are applied.

[0029] This area of ​​coil 1 is not used for its normal energy storage function, such as semiconductor commutation and meeting voltage ripple requirements, but rather as a return path for common-mode currents. To this end, this area is in contact with the ground of the system using the intermediate circuit capacitor and therefore coil 1, such as the vehicle frame, circuit board, or other component providing ground.

[0030] By electrically isolating the region 12 from the main region providing the positive or negative potential (which serves as a return path for the common-mode current and is connected to ground), a significantly shorter path can be provided for the common-mode current than previously. Thus, the previously required Y-type capacitors can be omitted.

[0031] The gap 2 separating the main area from the area 12 serving as the return path for the common mode current must be sized in such a way that the area of ​​the area 12 is equal to or greater than the coupling capacitance of the load or source, in the case of a motor, equal to or greater than the motor stray capacitance since it is proportional thereto.

[0032] like Figure 1As shown, the region 12 serving as the return path for the common mode current can be positioned at the end region (where the winding ends) or at the start region (where the winding begins) of the roll 1. It can also be positioned in the middle region as long as electrical contact can be achieved.

[0033] exist Figure 1 、 Figure 3 and Figure 4 In the embodiment shown, the region 12 serving as the return path for the common mode current is provided in only one of the metallization layers 10 and 11. However, regions serving as the return path for the common mode current may also be provided in both metallization layers 10, 11, such as Figure 2a (upper side of foil) and Figure 2b (underside of the foil) is shown as an example. In this case, the metallization layers 10, 11 do not occupy the entire width in the sub-areas, thus forming the sides of an L-shape. A region 12 serving as a return path for the common-mode current can then be arranged parallel to the sides. It is then separated from the metallization layers 10, 11 by two gaps 2.

[0034] The same fuse pattern as in conventional intermediate circuit capacitors can be used on metallization layers 10 and 11 to prevent a short circuit between one conductive section and the vehicle frame and to meet safety requirements. The purpose of the fuse pattern is to interrupt the conductive path for current in the event of membrane damage in one area, thereby isolating that area from the rest of the capacitor. This prevents short circuits between positive and negative potentials and the vehicle frame.

[0035] In one embodiment, additional fuses may be introduced by reducing the width of the current path in the region of the metallization layers 10, 11, e.g. Figure 3 and Figure 4 As shown by means of different embodiments. In this case, the metallization layer ( Figure 3 and Figure 4 A subregion 11.1 of the metallization layer 11 in the vehicle body is separated from the rest of the vehicle body by a gap 2. However, this separated subregion 11.1 is not connected to ground but is reconnected to the main body via a fuse. This minimizes the risk of shorting positive or negative potentials to the vehicle frame. In one design, subregion 11.1 is sized to correspond to region 12, which serves as the return path for the common-mode current, i.e., to be of approximately the same size. Figure 3 The embodiment in which the connecting tab 3 remains between the separated part and the main part is shown. In this embodiment, the metallization layer 11 is not separated by the gap 2. Figure 4An embodiment is shown in which the gap 2 is continuous and an external (electrical) connection is established between the spaced apart part and the main part, wherein an external connecting element 4 is provided which has the same function as the connecting tab 3, i.e. acts as a kind of fuse.

[0036] Fuses can be used in all embodiments of the present invention. For example, Figure 3 and Figure 4 In the embodiment shown, the fuse is provided in the metallization layer 10 or 11 (in the embodiment shown, the metallization layer 11), wherein no separate region 12 is provided for the return path of the common mode current. Figure 2a and 2b In the embodiment shown, the side edges of the metallization layers 10 and 11 can also be separated from the respective main regions by gaps 2 and connected to each other by fuses 3 or 4 .

[0037] Fuses can also be used to optimize the equivalent series resistance and, if necessary, damp certain system resonances in the spectrum. Furthermore, fuse patterns can be designed to adjust the series resistance in series with the capacitor accordingly. This fuse pattern can also be used to damp system resonances in the spectrum.

[0038] As previously mentioned, an intermediate circuit capacitor is generally formed from a plurality of interconnected coils 1, which form the capacitor coil of the intermediate circuit capacitor and are electrically contacted with the corresponding busbars. If the coils 1 described according to the present invention with modified metallization layers 10 and 11 are now used in the intermediate circuit capacitor, in particular, the originally required Y-type capacitors can be omitted, since their function is already provided by the modified coils 1.

[0039] In an advantageous embodiment, at least two capacitor windings are used, wherein the region 12 serving as the return path for the common mode current is distributed symmetrically between the windings 1, i.e. each winding 1 is implemented at an opposite potential (positive + or negative -), e.g. Figure 5 As shown. For example, in the first coil, the positive metallization layer remains unchanged, while the negative metallization layer is interrupted so that this part can be connected to the vehicle frame or ground. The second coil has no change in negative potential, but the positive metallization layer is interrupted and connected to the vehicle frame. In this way, a balance can be achieved between the two potentials from the perspective of common-mode current. This prevents certain common-mode currents from being converted into differential-mode currents that could cause additional, undesirable resonances in the interference spectrum. Of course, this principle can also be applied to all other designs of coil 1, that is, designs in which both metallization layers 10 and 11 are modified, that is, designs with area 12 serving as a return path for the common-mode current. The size of coil 1 in the intermediate circuit capacitor can also be varied.

[0040] Furthermore, it is also possible that the number of rolls 1 having regions 12 serving as return paths for the common-mode current in the metallization layer serving as the positive potential may be smaller or greater than the number of rolls 1 having regions 12 serving as return paths for the common-mode current in the metallization layer serving as the negative potential. Furthermore, it is also possible to provide only rolls 1 having regions 12 serving as return paths for the common-mode current in the metallization layer serving as the positive potential, or only rolls 1 having regions 12 serving as return paths for the common-mode current in the metallization layer serving as the negative potential.

[0041] By using the described coil 1 and the possibility of conducting common-mode currents over short paths, a complete intermediate circuit capacitor can be constructed. The entire intermediate circuit capacitor and the ground capacitance must be designed according to the system requirements. Finally, the connection between region 12, which serves as the return path for the common-mode current, and the vehicle frame or ground can be achieved via a connecting element 5, such as a pin connector, cable, or busbar, which is fastened to the capacitor coil (region 12), for example, by soldering or welding it thereto.

[0042] The proposed modification of the metallization layers 10 and 11 of coil 1, which serves as the intermediate circuit capacitor, allows common-mode currents to be shorted to the vehicle frame or ground near their source. This prevents these currents from propagating through the system and interfering with other functional modules. Furthermore, excellent high-frequency damping is achieved in the range above 10 MHz (including ultra-shortwave frequencies). Due to the elimination of joints, parasitic inductance is at least twice as low as in typical coils.

[0043] By being able to select the dimensions of the region 12 and the gap 2, the capacitance to ground can be varied in a simple manner without mechanically modifying the inverter. This makes it easier to adapt to system requirements and to implement modifications.

[0044] Since the typical winding of the intermediate circuit capacitor can be used to integrate the grounding capacitor by slightly adjusting the metallization, it can also be easily integrated into series production.

[0045] Furthermore, a high level of integration is achieved, which reduces the cost, size, and weight of the system. Therefore, with appropriate design, additional components such as Cy or even entire DC EMC filter modules can be eliminated, which has a positive impact on the overall cost, weight, and size of the inverter.

[0046] Furthermore, the resonances in the HVAN (High Voltage Artificial Network) spectrum can be adjusted. The resonances in this spectrum can be manipulated by adjusting the amplitude and / or frequency of the common-mode current. This can be achieved using the proposed principle.

[0047] The main indicator of the applicability of Volume 1 for the proposed modification is how severe the common mode currents are in the system. This problem is common to all systems with a B6 bridge and many types of multilevel inverters, DC voltage converters, active rectifiers, etc.

[0048] Such power electronics systems, i.e. systems with power semiconductors as switching elements, are used in a wide variety of applications, such as adjustable drives, systems for harvesting electrical energy, chargers, inductive energy transfer systems, high-voltage DC transmission lines, aircraft power supply systems, switched-mode power supplies, and in e-mobility.

[0049] In the field of electromobility, electronic modules are often used to operate the electric drive of a motor vehicle powered by a battery or fuel cell. The motor vehicle is particularly a commercial vehicle, such as a truck or bus, or a passenger car. The electronic modules include an inverter, intermediate circuit capacitors, and possibly other components such as EMC filters, heat sinks, AC / DC rectifiers, DC / DC converters, cycloconverters, and / or other electrical converters. In particular, power electronics modules are used to energize electric machines, such as electric motors and / or generators. A DC / AC inverter is preferably used to generate multiphase AC current from a DC voltage generated by an energy source, such as a battery. The DC / DC converter is used, for example, to convert (boost) the DC current from a fuel cell into a DC current that can be used by the drive.

[0050] Reference Signs List

[0051] 1 volume

[0052] 10 First metallization layer

[0053] 11 Second metallization layer

[0054] 11.1 Sub-areas

[0055] 12Area serving as the return path for common mode current (ground)

[0056] 13 Electrical insulation foil

[0057] 2 gaps

[0058] 3 connecting tabs (fuse)

[0059] 4 External connection elements (fuse)

[0060] 5Connection elements for ground / frame

Claims

1. A capacitor winding (1) of an intermediate circuit capacitor, comprising a first metallization layer (10; 11) serving as a positive potential and a second metallization layer (11; 10) serving as a negative potential, and further comprising at least one region (12) serving as a return path for a common-mode current, said region being formed from at least one of the metallization layers (10; 11) and being electrically isolated therefrom.

2. The capacitor coil (1) according to claim 1, wherein: The region (12) serving as a return path for the common mode current is electrically isolated from the remaining metallization layer (10; 11) by at least one continuous gap (2) passing through the metallization layer (10; 11).

3. The capacitor coil (1) according to claim 1 or 2, wherein: The region (12) serving as a return path for the common mode current is arranged at a starting region, an end region or a central region of the metallization layer (10; 11).

4. Capacitor coil (1) according to any one of the preceding claims, wherein The metallization layers (10; 11) are applied to mutually facing sides of a single electrically insulating foil (13), or wherein A plurality of electrically insulating foils (13) are provided, and a metallization layer (10; 11) is applied to one side of each of the electrically insulating foils (13).

5. Capacitor coil (1) according to any one of the preceding claims, wherein In the case where there is only one region (12) serving as a return path for the common mode current, the other metallization layer (10; 11) has a subregion (11.1) below the region (12) serving as a return path for the common mode current, the subregion being electrically isolated from the metallization layer (10; 11) such that: - electrically connected to the metallization layer (10; 11) via only one connecting tab (3), or - electrically connected to the metallization layer (10; 11) via an external connection element (4).

6. An intermediate circuit capacitor formed from a plurality of capacitor coils (1) according to any one of the preceding claims.

7. The intermediate circuit capacitor according to claim 6, wherein: - the number of capacitor windings (1) having areas (12) serving as return paths for common-mode currents in the metallization layer (10; 11) serving as positive potential is comparable to the number of capacitor windings (1) having areas (12) serving as return paths for common-mode currents in the metallization layer (10; 11) serving as negative potential, or - the number of capacitor windings (1) having an area (12) serving as a return path for the common mode current in the metallization layer (10; 11) serving as a positive potential is smaller or larger than the number of capacitor windings (1) having an area (12) serving as a return path for the common mode current in the metallization layer (10; 11) serving as a negative potential, or - A capacitor winding (1) having a region (12) serving as a return path for a common-mode current only in a metallization layer (10; 11) serving as a positive potential, or a capacitor winding (1) having a region (12) serving as a return path for a common-mode current only in a metallization layer (10; 11) serving as a negative potential. 8 . An electronics module comprising an inverter and an intermediate circuit capacitor according to claim 6 or 7 , which is electrically connected to the inverter.

9. An at least partially electrically driven vehicle having an electronics module according to claim 8, wherein: Each region (12) of the capacitor winding (1) of the intermediate circuit capacitor, which serves as a return path for the common mode current, is in contact with a component providing grounding.

10. The at least partially electrically driven vehicle according to claim 9, wherein: The component providing the ground is the frame of the vehicle or the circuit board of the electronics module.

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