High-voltage device with flat cover and protective device

Abstract

High-voltage device comprising: - a housing (1) with a removable, flat cover (10) in the area above a circuit board (3), and - an inverter (2) arranged in the housing (1) and electrically connected to a DC power source, comprising a printed circuit board (3) arranged on a side facing the cover (10) and forming a control unit of the inverter (2), and - a protective device which is connected to the control unit of the inverter (2) and is designed in such a way as to detect the removal of the cover (10) and then disconnects the connection to the DC power source, wherein the protective device has two components, one of which is a Hall sensor (4) and the other a magnet (5), wherein the first component is arranged on the circuit board (3), and wherein the second component is arranged on a bottom side of the cover (10) facing the circuit board (3) and opposite the first component at a predetermined distance (A) and without any other components such as a housing wall in between.

Description

[0001] The present invention relates to the field of electromobility.

[0002] The use of electronic modules, such as power electronic modules, in motor vehicles has increased significantly in recent decades. This is due, on the one hand, to the need to improve fuel efficiency and vehicle performance, and on the other hand, to advances in semiconductor technology. The main component of such an electronic module is a DC / AC inverter, which serves to supply electrical machines such as electric motors or generators with multiphase alternating current (AC). In this process, direct current generated by a DC energy source, such as a battery, is converted into multiphase alternating current. To this end, inverters comprise a variety of electronic components, such as semiconductor power switches, also known as power semiconductors.Due to the high currents and voltages and the associated risk of injury, measures are necessary to provide protection against accidental contact with high-voltage components such as the inverter's power electronics. Inverters are typically housed in a casing with a cover that protects the inverter's components from external influences. Additional protection against accidental contact is achieved by incorporating devices that, upon detection of the cover being removed, disconnect all live components of the inverter from the DC power source, thus switching the inverter to a safe mode. This protection is currently implemented by providing electrical conductors on one or both sides of the cover and between the cover and the inverter's circuit board. This is known as an interlock. To remove the cover, these conductors must be disconnected.Furthermore, there are measures for touch protection that detect when the cover is removed and subsequently disconnect the live components of the inverter from the DC power source. This is achieved, for example, by detecting the removal of the screws connecting the cover to the rest of the housing via the lines described above, as disclosed in DE 10 2018 221 908 A1. An alternative solution is proposed in DE 10 2019 135 137 A1, in which several cover elements with different geometries are provided and the sensor for detecting cover removal is embedded in one of the covers. Further prior art can be found in document DE 10 2012 015 252 A1, which discloses a reed sensor integrated into a housing cover.From DE 10 2006 029 977 B3 a position sensor is known which provides non-contact position measurement using a Hall sensor.

[0003] Since there is still room for improvement regarding the simplification of contact protection, the invention is based on the objective of providing improved contact protection for high-voltage devices. This objective is achieved by the features of the independent claims. Advantageous embodiments are the subject of the dependent claims.

[0004] A high-voltage device is proposed, comprising a housing with a removable lid, and an inverter arranged in the housing and electrically connected to a DC power source, comprising a printed circuit board arranged on a side facing the lid and forming the control unit of the inverter, and comprising a protective device which is connected to the control unit of the inverter and is configured to detect the removal of the lid and subsequently disconnects the connection to the DC power source, wherein the protective device comprises two components, one of which is a Hall sensor and the other a magnet, the first component being arranged on the printed circuit board.and wherein the second component is located on the underside of the cover facing the circuit board, opposite the first component and at a predetermined distance and without any other components such as a housing wall in between.

[0005] In one version, the first component is a Hall sensor and the second component is a magnet.

[0006] In one embodiment, a spacer element is arranged on the underside of the lid, on which the second component is arranged, with the spacer element and the second component being attached to the lid.

[0007] In one version, the spacer element and the second component are formed as a single unit.

[0008] One version includes a counting unit that counts the frequency with which the lid is removed.

[0009] In one version, the counting unit only starts counting after a predetermined operating time upon initial use.

[0010] Furthermore, an electric axle drive comprising the high-voltage device is provided. Additionally, a vehicle with at least one electric axle driven by the electric axle drive is provided.

[0011] Further features and advantages of the invention will become apparent from the following description of exemplary embodiments of the invention, with reference to the figures in the drawing, which shows details of the invention, and from the claims. The individual features can be implemented individually or in any combination in a variant of the invention.

[0012] Preferred embodiments of the invention are explained in more detail below with reference to the accompanying drawing. Fig. Figure 1 shows a basic structure of a high-voltage device with a closed lid, according to an embodiment of the present invention. Fig. Figure 2 shows a basic structure of a high-voltage device with an open lid, according to an embodiment of the present invention.

[0013] In the following figure descriptions, identical elements or functions are marked with the same reference symbols.

[0014] As mentioned at the outset, an inverter 2, located in a vehicle that is at least partially electrically powered, is housed in a casing 1 with a cover 10. The casing 1, enclosed by the cover 10, protects the components of the inverter 2 from external influences. Due to the high currents and voltages in HV (high voltage) applications, it also serves as contact protection. This protective device functions by putting the inverter into a safe mode, i.e., a de-energized mode, when the cover 10 of the casing 1 is removed (opened).

[0015] Since current solutions are sometimes very complicated, an alternative protective device for contact protection is proposed below, which requires no additional steps when removing the cover 10. Furthermore, installation is simple and does not require any geometric modification or a complex geometry of the cover 10.

[0016] As is known from the prior art, a housing 1 with a cover 10 is provided, in which the inverter 2 is arranged. A populated circuit board 3, which serves as the control unit for the inverter 2 and is accordingly connected to it, is arranged on the top of the inverter 2 and in the housing 1 below the cover 10. The cover 10 is essentially flat in the area above the circuit board 3.

[0017] The required contact protection is achieved by means of a protective device with two components, one of which is a Hall sensor 4 and the other a magnet 5, to provide non-contact detection of whether the cover 10 is removed or closed. The protective device is therefore connected to the inverter's control unit to provide it with information on whether the cover 10 has been detected as being removed or whether it is still closed, so that the control unit can initiate appropriate contact protection measures.

[0018] According to the invention, one of the components is attached to the underside of the cover 10. The other component is arranged as directly opposite it as possible on the circuit board 3. The component located on the circuit board 3, the Hall sensor 4, is advantageous because it can then be directly contacted via conductor tracks on the circuit board 3 with the control unit, which represents at least partially integrated hardware and software of the inverter 2, in order to put the inverter 2 into safe mode when the cover 10 is removed. Opposite the Hall sensor 4, the magnet 5 (preferably a permanent magnet) is provided. This is attached to the underside of the cover 10. Thus, when the cover 10 is closed, the Hall sensor 4 and the magnet 5 are arranged at a distance A from each other, without touching each other and without any other components, such as a housing wall, between them.The arrangement must be such that the distance A when the lid is closed is only so large that the Hall sensor 5 can detect the magnetic field of the magnet 5 and thus output a signal (e.g. "high") that indicates to the control unit of the inverter 2 (on the circuit board 3) that the lid 10 is closed, as in . Fig. 1 schematically indicated. If the distance A becomes too large, i.e., if the cover 10 is removed, then the Hall sensor 5 can no longer detect the magnetic field of the magnet 5. It can then output a corresponding signal (e.g., "low") that indicates to the control unit of the inverter 2 (on the circuit board 3) that the cover 10 is open, as shown in Fig. 2 is shown schematically. In this case, the control unit can then react and disconnect the live components of inverter 2 from the DC power source.

[0019] Depending on the lid geometry and the positioning of the Hall sensor 4 and magnet 5, it may be necessary to provide a spacer element 6, e.g., in the form of a pedestal, on the lid 10 to ensure the required (small) distance A between the Hall sensor 4 and the magnet 5, as indicated in the figures. The spacer element 6 serves merely as a spacer positioned between the underside of the lid 10 and the magnet 5. Advantageously, it is made of a non-electrically conductive material. In one embodiment, the magnet 5 can also be formed as a single unit with the spacer element 6, such that the spacer element 6 is magnetic at one end.

[0020] Both the magnet 5 without spacer 6 and the magnet 5 together with spacer 6 can be attached to the lid 10. For example, the magnet 5 can have a screw that can be screwed directly into the lid (and then also attach the spacer 6).

[0021] By providing a Hall sensor, non-contact detection can be made as to whether the cover 10 is closed or removed, so that a disconnection from the power supply (by the control unit) can take place.

[0022] In another version, a counting unit can be provided that records the frequency with which the lid 10 is removed. For example, only the "high" signal can be counted. This allows for a simple check to determine whether the lid 10 has been (unauthorized) removed during its operating time.

[0023] To provide more precise verification, it can be arranged that the removal of cover 10, for example by service personnel, can be registered as authorized in the control unit of inverter 2. Alternatively or additionally, it can be arranged that the counter unit only starts counting after a predetermined operating time, so as not to count any openings of cover 10 that may be necessary during installation or commissioning. For example, it can be arranged that counting only starts once inverter 2 has been in continuous operation for a certain period, e.g., a few minutes. The counter reading can be read from the counter unit in the usual manner.

[0024] The described high-voltage device is used, for example, in partially electrically powered vehicles, particularly those with electrically driven axles. The vehicle is typically a commercial vehicle such as a truck or bus, or a passenger car. The inverter (DC / AC inverter) serves to generate a multi-phase alternating current from a direct current (DC) produced by an energy source, such as a battery. Reference symbol list 1 case 10 lids 2 Inverter 3 circuit boards 4 Hall sensor 5 Magnet with N / S 6 spacer elements A distance between 4 and 5

Claims

[1] High-voltage device comprising: - a housing (1) with a removable, flat cover (10) in the area above a circuit board (3), and - an inverter (2) arranged in the housing (1) and electrically connected to a DC power source, comprising a printed circuit board (3) arranged on a side facing the cover (10) and forming a control unit of the inverter (2), and - a protective device which is connected to the control unit of the inverter (2) and is designed in such a way as to detect the removal of the cover (10) and then disconnects the connection to the DC power source, wherein the protective device has two components, one of which is a Hall sensor (4) and the other a magnet (5), wherein the first component is arranged on the circuit board (3), and wherein the second component is arranged on a bottom side of the cover (10) facing the circuit board (3) and opposite the first component at a predetermined distance (A) and without any other components such as a housing wall in between. [2] High-voltage device according to claim 1, wherein the first component is formed as a Hall sensor (4) and the second component as a magnet (5). [3] High-voltage device according to claim 1 or 2, wherein a spacer element (6) is arranged on the underside of the cover (10), on which the second component is arranged, wherein the spacer element (6) and the second component are attached to the cover (10). [4] High-voltage device according to claim 3, wherein the spacer element (6) and the second component are formed as a unit. [5] High-voltage device according to one of the preceding claims, wherein a counting unit is provided which counts the frequency of removing the cover (10). [6] High-voltage device according to claim 5, wherein the counting unit only starts counting after a predetermined operating time on first use. [7] Electric axle drive comprising a high-voltage device according to one of the preceding claims. [8] Vehicle comprising at least one electric axle driven by an electric axle drive according to claim 7.

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