High-voltage electrical system with electrical and mechanical safety measures for a motor vehicle

Abstract

The invention relates to a high-voltage electrical system (1) for a motor vehicle having: - an electrical drive unit (2) with a first high-voltage component in the form of a high-voltage energy store (4) and at least one second high-voltage component in the form of a permanently energised electrical machine (5a, 5b), wherein the high-voltage components also have at least temporarily live parts in the event of an accident involving the motor vehicle, - at least one auxiliary consumer (3) electrically connected to the electrical drive unit (2), - a first protective device (10) for providing an electrical protective measure for the at least one auxiliary consumer (3) which, in the event of an accident, is designed to disconnect the at least one auxiliary consumer (3) from the electrical drive unit (2) in order to prevent a voltage induced by the permanently energised electrical machine (5a, 5b) from being fed in and to discharge it in order to allow an accident-related mechanical deformation, and - a second protective device (14) for providing a mechanical protective measure for the electrical drive unit (2), which is designed to absorb an accidental application of force to the electrical drive unit (2) to prevent an accidental mechanical deformation of the high-voltage components.

Description

[0001] High-voltage electrical system with electrical and mechanical safety measures for a motor vehicle

[0002] The invention relates to a high-voltage electrical system for a motor vehicle. The high-voltage electrical system comprises an electric drive unit with a first high-voltage component in the form of a high-voltage energy storage device and with at least one second high-voltage component in the form of a permanent-magnet electric machine. The high-voltage components comprise live parts at least temporarily, even in the event of an accident involving the motor vehicle. Furthermore, the high-voltage electrical system comprises at least one auxiliary consumer electrically connected to the electric drive unit. The invention also relates to a motor vehicle with a high-voltage electrical system.

[0003] In the present case, interest is directed to high-voltage on-board electrical systems of electrified motor vehicles, which have an electric drive unit and at least one auxiliary consumer or at least one auxiliary assembly. The electric drive unit has, for example, high-voltage components in the form of a high-voltage energy storage device and at least one electric drive motor. The at least one electric drive motor is connected to the high-voltage energy storage device via an inverter and a high-voltage intermediate circuit. The at least one auxiliary consumer, for example an air conditioning compressor, a heating device, a pump, or the like, is also connected to the electric drive unit, for example to the high-voltage intermediate circuit, so that the at least one auxiliary consumer can be supplied with energy from the high-voltage energy storage device.

[0004] The high-voltage electrical system is typically designed in such a way that, in the event of a motor vehicle accident, no danger arises from live, particularly voltage-generating, parts of the high-voltage components. For this purpose, the high-voltage components can be protected from accident-related mechanical deformation or destruction, for example, with mechanical protective elements. In the case of a drive unit with a permanently excited electric drive motor, it can happen that, when the rotor of the drive motor, which is equipped with permanent magnets, rotates, a voltage is induced and fed into at least one auxiliary consumer, so that this consumer must also be protected, for example with mechanical protective elements. However, such mechanical protective elements undesirably increase the weight and cost of the motor vehicle and require a lot of installation space.

[0005] It is an object of the present invention to provide a simple, cost-, space- and weight-saving solution for providing a safe state for a high-voltage vehicle electrical system in the event of an accident involving the motor vehicle.

[0006] This object is achieved according to the invention by a high-voltage electrical system and a motor vehicle according to the respective independent patent claims. Advantageous embodiments of the invention are the subject of the dependent patent claims, the description, and the figure.

[0007] A high-voltage electrical system according to the invention for a motor vehicle comprises an electric drive unit with a first high-voltage component in the form of a high-voltage energy storage device and at least one second high-voltage component in the form of a permanently excited electric machine, wherein the high-voltage components have live parts at least temporarily, even in the event of an accident involving the motor vehicle. The high-voltage electrical system also has at least one auxiliary consumer electrically connected to the electric drive unit. Furthermore, the high-voltage electrical system has a first protective device for providing an electrical protective measure for the at least one auxiliary consumer and a second protective device for providing a mechanical protective measure for the electric drive unit.In the event of a motor vehicle accident, the first protective device is designed to disconnect at least one auxiliary load from the electric drive unit to prevent the feed-in of a voltage induced by the permanent-magnet electric machine and to discharge it to allow for accident-related mechanical deformation. The second protective device is designed to prevent an accident-related force being applied to the electric drive unit to prevent accident-related mechanical deformation of the live high-voltage components.

[0008] A motor vehicle according to the invention comprises a high-voltage on-board electrical system according to the invention. The motor vehicle is an electrified motor vehicle and has at least one permanent-magnet electric machine as a drive motor. The permanent-magnet electric machine has a stator with energizable stator windings for exciting a stator magnetic field and a rotor with permanent magnets for exciting a rotor magnetic field. The high-voltage energy storage unit supplies the stator windings of the at least one permanent-magnet electric machine and the at least one auxiliary consumer, for example an air conditioning component of an air conditioning circuit of the motor vehicle, with electrical energy. For this purpose, the electric drive unit has a high-voltage intermediate circuit electrically connected to the high-voltage energy storage unit, to which the at least one auxiliary consumer and, via an inverter, the at least one permanent-magnet electric machine are connected.The permanent-magnet electric machine and at least one auxiliary load are thus also electrically connected via the high-voltage intermediate circuit. The high-voltage energy storage device has, for example, a switching device with at least one contactor, via which the high-voltage energy storage device is switchably connected to the high-voltage intermediate circuit. The switching device can be used to disconnect the high-voltage energy storage device from the high-voltage intermediate circuit, for example in the event of a motor vehicle accident, so that no more voltage is fed into the high-voltage intermediate circuit from the high-voltage energy storage device. However, even when the high-voltage energy storage device is disconnected and the switching device is open, energy storage cells of the high-voltage energy storage device are live or voltage-generating parts of the high-voltage energy storage device and cannot be de-energized.In the event of an accident, the rotating rotor of the permanent magnet electrical machine is also a part that is at least temporarily live or generates voltage, and which can only be de-energized after a certain time by stopping the rotor.

[0009] The first protective device is provided to prevent the voltage-generating parts of the high-voltage components from continuing to feed voltage into the at least one auxiliary load in the event of a motor vehicle accident. The first protective device provides an electrical protective measure for the at least one auxiliary load, by which the at least one auxiliary load can be transferred to a de-energized state and thus does not need to be protected by a deformation-preventing mechanical protective measure. In other words, accident-related deformation, in particular destruction, of the at least one auxiliary load is permitted after the at least one auxiliary load has been restored to a de-energized state.The electrical protective measure includes disconnecting the at least one auxiliary consumer from the high-voltage intermediate circuit and thus from the electric drive unit, as well as discharging the at least one auxiliary consumer. To disconnect the at least one auxiliary consumer from the electric drive unit, at least one connection of the at least one auxiliary consumer, in particular all connections of the at least one auxiliary consumer, are disconnected from the drive unit. For this purpose, for example, a connecting line via which the at least one auxiliary consumer is connected to the high-voltage intermediate circuit can be severed. To discharge the at least one auxiliary consumer, the first protective device is designed, for example, to short-circuit connections of the at least one auxiliary consumer.After the voltage-free state of at least one secondary consumer has been established, it can be deformed due to an accident without the at least one destroyed secondary consumer posing any danger, for example a contact protection problem.

[0010] Since the electric drive unit has high-voltage components with at least temporarily live parts, the electric drive unit cannot be completely de-energized or de-energized even in the event of an accident. This is particularly problematic if the live parts of the high-voltage components are exposed due to the destruction of the high-voltage components. Therefore, the second protective device is provided, which protects the high-voltage components of the electric drive unit, in particular the high-voltage energy storage device, the at least one permanent-magnet electric machine, the inverter, and the connecting cables of the electric drive unit, from destruction and prevents excessive accident-related deformation of the components of the electric drive unit.

[0011] The high-voltage electrical system is designed in such a way that only those high-voltage components of the high-voltage electrical system that cannot be deactivated or cannot be fully deactivated and thus contain live parts, at least temporarily, are protected from accident-related deformation. However, deformation of at least one auxiliary consumer is permitted after it has been transferred to an intrinsically safe, de-energized state. This advantageously saves costs, installation space, and weight on the vehicle.

[0012] In one embodiment of the first protective device, it comprises an overcurrent protection device, which may, for example, comprise at least one fuse, for interrupting the connecting line, and a closing element, for example a pyrotechnic contact or a semiconductor switch, for electrically connecting the terminals of the at least one auxiliary load. The overcurrent protection device cuts electrical conductors of the connecting line connected to the terminals of the at least one auxiliary load. The closing element short-circuits the terminals of the at least one auxiliary load to discharge the power.

[0013] In another embodiment of the first protective device, it comprises a, in particular, pyrotechnic disconnection unit, which is designed to sever the connecting line between the at least one auxiliary load and the electric drive unit and to electrically connect the electrical conductors of the severed connecting line that are electrically connected to the terminals of the at least one auxiliary load. The disconnection unit, which is mounted on the connecting line in a non-destructively detachable manner, is thus designed both to interrupt the connecting line and to short-circuit the terminals.For this purpose, the separating unit comprises, for example, a pyrotechnically driven separating element which divides the connecting line into two connecting line sections, namely a drive-side connecting line section and a secondary consumer-side connecting line section, wherein the separating element is arranged in a separating position between the two connecting line sections. The separating element has an electrically insulating region which, in the separating position, is arranged on the drive-side connecting line section and thus insulates electrical conductors of the drive-side connecting line section from one another. In addition, the separating element has the electrically conductive region which, in the separating position, is arranged on the secondary consumer-side connecting line section and electrically connects the conductors of the secondary consumer-side connecting line section connected to the terminals of the secondary consumer, in order to short-circuit the terminals.For example, the separating element can have an electrically insulating separating piston which is metallically coated on one side.

[0014] It can be provided that the second protective device comprises at least one mechanical protective element that covers the electric drive unit at least in part and is designed to absorb the impact force caused by an accident. For example, the at least one mechanical protective element is a protective plate and / or a foam. The second protective device can also comprise a cable duct for protecting the connecting cables of the electric drive unit. The embodiments presented with reference to the high-voltage electrical system according to the invention and their advantages apply accordingly to the motor vehicle according to the invention.

[0015] Further features of the invention emerge from the claims, the figure, and the description of the figures. The features and combinations of features mentioned above in the description, as well as the features and combinations of features mentioned below in the description of the figures and / or shown alone in the figure, can be used not only in the respective specified combination, but also in other combinations or on their own.

[0016] The invention will now be explained in more detail using a preferred embodiment and with reference to the drawing.

[0017] The single figure, Fig. 1, shows a schematic representation of a high-voltage on-board electrical system 1 for an electrified motor vehicle. The high-voltage on-board electrical system 1 has an electric drive unit 2 and at least one auxiliary consumer 3. The electric drive unit 2 has high-voltage components in the form of a high-voltage energy storage device 4 acting as a traction battery and two permanently excited electric machines 5a, 5b. A first permanently excited electric machine 5a is designed as the drive machine of a front axle of the motor vehicle and a second permanently excited electric machine 5b is designed as the drive machine of a rear axle of the motor vehicle. The high-voltage energy storage device 4 has a switching device 6, via which an interconnection 7 of energy storage cells 8 is connected to the permanently excited electric machines 5a, 5b.The electric drive unit 2 represents a first high-voltage electrical system area 1a that cannot be de-energized. In the event of an accident, its high-voltage components have permanently or temporarily live parts. Such parts include, for example, the energy storage cells 8 of the high-voltage energy storage unit 4 and rotating rotors 9 of the permanently excited electric motors 5a, 5b, which are equipped with permanent magnets and can induce voltage into the high-voltage electrical system 1.

[0018] The at least one auxiliary consumer 3 belongs to a second high-voltage electrical system area 1b, which can be de-energized and de-energized. To ensure this de-energization of the second high-voltage electrical system area 1b in the event of an accident involving the motor vehicle, the high-voltage electrical system 1 has a first protective device 10 for providing an electrical protective measure, which disconnects and discharges the at least one auxiliary consumer 3 from the live high-voltage components of the first high-voltage electrical system area 1a. Here, the first protective device 10 has an overcurrent protection device 11, for example a fuse 12, which can disconnect the at least one auxiliary consumer 3 from the electric drive unit 2 and thus from the first high-voltage electrical system area 1a in the event of a fault.In addition, the first protection device 10 here has a pyrotechnic contact 13, which short-circuits terminals of the at least one auxiliary consumer 3 to discharge the at least one auxiliary consumer 3. This establishes the voltage-free state of the second high-voltage electrical system area 1b. In the exemplary embodiment shown here, the first protection device 10 is arranged in the high-voltage energy storage device 4. However, the first protection device 10 can also be arranged, at least partially, outside the high-voltage energy storage device 4.

[0019] To protect the first high-voltage electrical system area 1a, the high-voltage electrical system 1 has a second protective device 14 for providing a mechanical protective measure. The second protective device 14 here has mechanical protective elements 15, for example, protective plates, which cover the high-voltage energy storage device 4 and the permanent-magnet electrical machines 5a, 5b at least in part and absorb any force applied in an accident. This prevents deformation of the high-voltage components and thus exposure of the live parts of the high-voltage components of the electric drive unit 2. Furthermore, the second protective device 14 here has cable ducts 16 for accommodating and protecting connecting lines 17 of the electric drive unit 2. The high-voltage electrical system areas 1a, 1b thus have different protective devices 10, 14, which provide different protective measures.

Claims

Patent claims 1. High-voltage electrical system (1) for a motor vehicle, comprising: - an electric drive unit (2) with a first high-voltage component in the form of a high-voltage energy storage device (4) and at least one second high-voltage component in the form of a permanently excited electric machine (5a, 5b), wherein the high-voltage components have live parts at least temporarily even in the event of an accident involving the motor vehicle, - at least one auxiliary consumer (3) electrically connected to the electric drive unit (2), characterized by - a first protective device (10) for providing an electrical protective measure for the at least one secondary consumer (3), which, in the event of an accident, is designed to separate the at least one secondary consumer (3) from the electric drive unit (2) to prevent the feeding of a voltage induced by the permanent magnet electric machine (5a, 5b) and to discharge it to allow an accident-related mechanical deformation, and - a second protective device (14) for providing a mechanical protective measure for the electric drive unit (2), which is designed to absorb an accident-related force applied to the electric drive unit (2) in order to prevent an accident-related mechanical deformation of the high-voltage components.

2. High-voltage vehicle electrical system (1) according to claim 1, characterized in that the first protective device (10) is designed to short-circuit terminals of the at least one secondary consumer (3) in order to discharge the at least one secondary consumer (3).

3. High-voltage vehicle electrical system (1) according to claim 2, characterized in that the first protective device (10) has an overcurrent protection device (11) for interrupting a connecting line connected to the terminals of the at least one secondary consumer (3) and the electric drive unit (2) and a closing element, in particular a pyrotechnic closer (13) and / or a semiconductor switch, for short-circuiting the terminals of the at least one secondary consumer (3).

4. High-voltage vehicle electrical system (1) according to claim 3, characterized in that the overcurrent protection device (11) has at least one fuse (12).

5. High-voltage vehicle electrical system (1) according to claim 2, characterized in that the first protective device (10) has a, in particular pyrotechnic, separation unit which is designed to sever a connecting line connected to the terminals of the at least one secondary consumer (3) and the electric drive unit (2) and to electrically connect two electrical conductors of the severed connecting line which are electrically connected to the terminals of the at least one secondary consumer (3).

6. High-voltage vehicle electrical system (1) according to claim 5, characterized in that the separating unit has a pyrotechnically activatable separating element which has an electrically conductive region for electrically connecting the two conductors of the severed connecting line.

7. High-voltage vehicle electrical system (1) according to one of the preceding claims, characterized in that the second protective device (14) has at least one mechanical protective element (15) which covers the high-voltage components of the electric drive unit (2) at least in regions and is designed to protect the accident-related to absorb force.

8. High-voltage vehicle electrical system (1) according to claim 7, characterized in that the at least one mechanical protective element (15) is a protective plate and / or a foam.

9. High-voltage vehicle electrical system (1) according to one of the preceding claims, characterized in that the second protective device (14) has at least one cable duct (16) for receiving and protecting connecting lines (16) of the electric drive unit (2).

10. Motor vehicle comprising a high-voltage electrical system (1) according to one of the preceding claims.

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