Vehicle onboard power grid

Abstract

The vehicle onboard power system (FB) is equipped with a DC voltage charging terminal (GA), a battery (AK), a first DC voltage converter (W1) and an electric drive (I, M). The first DC voltage converter (GW) has a first side (1S). The first side is connected to a connection point (VP) via a first switch (S1). The first DC voltage converter (GW) has a second side (2S), to which the electric drive (I, M) is connected. The second side is connected to the battery (AK) via a second switch (S2) and via a connection point (VP) or is directly connected to the battery (AK). The vehicle onboard power system has a second DC voltage converter (W2). The second DC voltage converter is connected to one side of the first switch (S1).

Description

Background Art

[0001] Vehicles with electric drives have batteries that can supply energy to the electric drives. It is known that vehicles have corresponding charging terminals (“plug-in vehicles”) for charging the batteries. The functions of charging and supplying the electric drives are performed by the vehicle electrical system. In addition, there are electrical consumers that can be supplied with a lower voltage than the electric drives, for example 12 V onboard electronics. Summary of the invention

[0002] The object is therefore to provide a possibility by which a battery or an electric drive can be supplied with a lower voltage on the one hand and an electrical consumer on the other hand in a simple manner.

[0003] This object is achieved by the vehicle onboard electrical system according to the invention. Further characteristics, features, embodiments and advantages emerge from the description and the drawings.

[0004] The vehicle electrical system described here has a battery, a first DC voltage converter, a second DC voltage converter and an electric drive. The battery is connected to a first side of the first DC voltage converter via a first switch and to a second side of the DC voltage converter via a second switch. The electric drive is connected to the second side of the converter, while the second DC voltage converter is connected to the first side of the first DC voltage converter (directly or via the first switch).

[0005] Thus, since the second DC voltage converter can be electrically disconnected from the electric drive using the first converter and the second switch, the electric drive is arranged separately from the voltage source for the second DC voltage converter. In addition, this behavior allows that the battery is connected to the second DC voltage converter and that the second DC voltage converter can be powered while the electric drive is disconnected.

[0006] Thus, if the electric drive is defective or a fault is detectable on the second side of the first DC voltage converter, at least one safety-related system of the vehicle can be supplied with power by means of the second DC voltage converter, for example, a component such as an electric steering device or a control device of an electric brake (or the electric brake itself). Thus, a short circuit on the second side of the first converter, for example caused by the electric drive, can be separated from the second DC voltage converter by means of the second switch and the first DC voltage converter. Furthermore, a fault on the second side of the first DC voltage converter can be separated from the battery by means of the first DC voltage converter and the second switch, but in this case, the battery can supply power to the second DC voltage converter. Thus, the second switch (and the first DC voltage converter) is used to separate the possibly defective power supply segment in which the electric drive is located, while the segment of the onboard power supply that supplies the second DC voltage converter can be supplied by the battery. Furthermore, the second DC voltage converter allows the voltage level of the power supply device to be adapted to the operating voltage suitable for the mentioned components.

[0007] Thus, there is a connection point to which the battery is connected and from which the first switch and the second switch proceed in order to connect the connection point to the first side or the second side of the first DC voltage converter. Since the second DC voltage converter is connected to the connection point or to the first side of the first DC voltage converter and the connection point itself is connected to the battery, a part of the onboard power supply system, in particular the part in which the electric drive is located, can be shut down by means of the second switch, which leads to the second side of the first DC voltage converter, so that the electric drive can be disconnected in the event of a defect.

[0008] Safety-relevant components, such as electric brakes, electric steering or their control devices, are connected to the second DC voltage converter, wherein other components, such as driver assistance systems, may also be connected to the second DC voltage converter.

[0009] The DC voltage terminal can also be connected to the connection point (for example via a switch). As a result, during the DC voltage charging, the second DC voltage converter and thus the components connected thereto can be supplied via the connection point without the first DC voltage converter having to be active. Since the battery and the second DC voltage converter are connected to the same connection point, to which the DC voltage charging terminal is also connected, energy can also be transferred from the connection point or the DC voltage terminal or the battery to the second DC voltage converter during the transfer of energy from the DC voltage charging terminal to the battery.

[0010] A vehicle onboard power system is described, which has a DC voltage charging terminal, a battery, a first DC voltage converter and an electric drive. The first DC voltage converter (hereinafter also referred to as: first converter) has a first side, which is connected to a connection point via a first switch. The first converter has a second side, and the electric drive is connected to the second side. The converter is set up to transfer energy between the first side and the second side, and to change the voltage level. (This also applies to the second converter). The second side of the first converter is connected to the battery, for example, directly or via a second switch and via a connection point. The vehicle onboard power system has a second DC voltage converter, which is connected to one side of the first switch. The second DC voltage converter is therefore either directly or connected to the connection point via the first switch. In other words, the second DC voltage converter is either directly or connected to the first side of the first converter via the first switch. The second DC voltage converter is also referred to as the second converter hereinafter.

[0011] The vehicle onboard power supply is preferably a high-voltage onboard power supply. The DC voltage charging terminal is preferably designed according to standards for wired charging. The battery is preferably a traction battery, wherein the electric drive is preferably used as a drive of the vehicle and is therefore connected to the output of the vehicle. This relates in particular to vehicles provided with a vehicle onboard power supply. The battery is, for example, a lithium battery. The switch mentioned here is preferably bipolar and is designed to separate the positive or negative voltage potential respectively (thus full-pole connection) or to provide a corresponding connection in the respective potential.

[0012] The second DC voltage converter is preferably connected (directly, i.e. without switches and converters) to the first side of the first DC voltage converter or can be connected (directly) to the connection point. In particular, the second DC voltage converter is connected to the battery directly, via the first switch and / or via a switch for connecting the battery to the remaining onboard electrical system.

[0013] The battery is preferably connected to the connection point via a third switch. The third switch is used to connect the battery to the remaining onboard power supply in a switchable manner. The third switch and the battery can be arranged in a first housing, while the second switch and the converter are arranged in another housing. A detachable plug connection can be arranged between the third switch and the remaining onboard power supply of the vehicle. Thus, the third switch can be connected to the remaining onboard power supply via a detachable connection. The detachable connection comprises in particular at least one plug terminal and an (at least two-core) cable.

[0014] Preferably, the first DC voltage converter and the second DC voltage converter are each designed as a galvanically isolated DC voltage converter. Therefore, the converters each include at least one transformer, which galvanically isolates the first side of the converter from the second side of the converter. The first DC voltage converter and the second DC voltage converter can therefore have a chopper, at least one transformer and a rectifier (the chopper, at least one transformer and the rectifier are connected to each other in this order) in order to thereby convert the first DC voltage and the second DC voltage.

[0015] In particular, the vehicle onboard power system comprises a low-voltage onboard power system branch, which is connected to one side of the first switch (or to a connection point or to a battery) via a second DC voltage converter. Therefore, the low-voltage onboard power system branch can be powered from the first side of the converter or from the connection point via the second converter. The low-voltage onboard power system branch has a nominal voltage of 12 volts, 13 volts or 14 volts, in particular 12 to 14 volts or substantially 24 volts. The low-voltage onboard power system branch can also have a nominal voltage of 48 volts. The second DC voltage converter is set up to send a voltage of 12 to 14 volts, substantially 24 volts or substantially 48 volts on the side where the second DC voltage converter is connected to the low-voltage onboard power system branch. The opposite side of the second converter is set up to work with a voltage of substantially 400 volts, 600 volts or 800 volts, and the mentioned nominal voltage of the low-voltage onboard power system branch is generated from this voltage.

[0016] The second DC voltage converter can also have a transformer as a galvanic isolating converter, in particular a galvanic isolating transformer. The second DC voltage converter has in particular a chopper, a galvanic isolating transformer and a rectifier, which are connected to one another in this order.

[0017] The second DC voltage converter has a high-voltage side, which is connected to one side of the first switch (and thus to the first side of the converter or to the connection point). The high-voltage side can also be regarded as the first side of the second DC voltage converter, while the second side of the second converter is connected to the low-voltage vehicle electrical system branch.

[0018] The DC voltage charging terminal is preferably connected to the connection point via a fourth switch. In particular, the DC voltage charging terminal is connected to the first switch or to the third switch via the fourth switch. In addition, the DC voltage charging terminal is connected to the second switch via the fourth switch. The DC voltage charging terminal is connected to the first converter or to its first side, in particular, via the fourth switch and the first switch downstream thereof.

[0019] The vehicle electrical system can also have an AC voltage charging terminal. The AC voltage charging terminal is preferably connected to the first side of the DC voltage converter via a rectifier device of the vehicle electrical system. The rectifier thus has an AC voltage side connected to the AC voltage charging terminal and also has a DC voltage side connected to the first converter or to its first side. In particular, the AC voltage charging terminal is connected to the first switch via the rectifier device.

[0020] The AC voltage charging terminal is connected to the connection point via a rectifier device and a first downstream switch. The battery is also connected to the connection point via a third switch, so that the AC voltage terminal can charge the battery via the rectifier and via the relevant switch. The rectifier device is preferably configured as a power factor correction filter and therefore has a rectification and step-up conversion (hochsetzstellende) function. The rectifier device is preferably configured as three-phase, but can also be configured as single-phase. The AC voltage charging terminal is also preferably configured as three-phase, but can also be configured as single-phase. The rectifier device can be configured as a full-wave rectifier, preferably as a three-phase full-wave rectifier or as a single-phase full-wave rectifier. The rectifier device can also be configured as a controllable or uncontrollable rectifier. The rectifier device is preferably configured as a power factor correction filter, in particular a Vienna filter.

[0021] The right-hand voltage charging terminal and the DC voltage charging terminal can be arranged in the same charging terminal module and are preferably designed in accordance with a standard for charging electrically operated vehicles.

[0022] It can be provided that the third switch is connected to the connection point via a detachable connection. As mentioned above, the detachable connection can include at least one plug connection element, preferably at least two plug elements, which are connected to each other via an (at least two-core) cable. Thus, the third switch and the battery can be accommodated in a housing which is connected to at least part of the remaining vehicle electrical system via the detachable connection.

[0023] The battery and the third switch on the one hand and the first switch, the second switch, the first DC voltage converter and the second DC voltage converter on the other hand can be arranged in different housings. Thus, the first housing can surround the battery and the third switch, while the second housing surrounds neither the battery nor the third switch, but at least the first switch, the second switch, the first DC voltage converter and the second DC voltage converter.

[0024] The electric drive is preferably designed as a high-voltage component and in particular has a nominal voltage of at least 400 volts, 600 volts or 800 volts. Alternatively or in combination therewith, at least one further high-voltage component can be connected to the second side of the first converter. The further high-voltage component can be, for example, an electrically heatable catalytic converter or another electrical heating device or an electric motor for driving an electric compressor.

[0025] The second DC voltage converter is preferably constructed as a multiphase. In this case, the second DC voltage converter includes a plurality of single converters. The single converters are connected to each other at the side of the DC voltage converter connected to the low-voltage onboard power supply branch, preferably connected in parallel. A plurality of single converters can be connected to the first side of the first switch via a configuration circuit, in particular to the first side of the first converter or to a connection point. The configuration circuit is established for connecting the single converters in series with each other in a first configuration state and connecting the single converters in parallel with each other in a second configuration state. This particularly relates to the side of each single converter connected to one side of the first switch. In other words, the configuration circuit is connected to the side of the second converter that deviates from the low-voltage onboard power supply branch.

[0026] It can be provided that each individual converter has an intermediate circuit capacitor (Zwischenkreiskondensator). The intermediate circuit capacitor is preferably arranged at the point where the single converter is connected to the configuration circuit. Each single converter therefore includes an intermediate circuit capacitor, which is connected to one side of the first switch via the configuration circuit. The intermediate circuit capacitors are connected in series or in parallel with each other according to the configuration state. In other words, the configuration circuit is designed to connect the intermediate circuit capacitors in parallel or in series with each other in different configuration states. In particular, when the configuration circuit is in the first configuration state, the intermediate circuit capacitors are connected in series with each other. When the configuration circuit is in the second configuration state, the intermediate circuit capacitors are connected in parallel with each other. The intermediate circuit capacitor is especially arranged at the input end of the single converter. The intermediate circuit capacitor is located on the side of the second converter that is away from the low-voltage onboard power supply branch.

[0027] The low-voltage battery can be located in the low-voltage onboard power supply branch, while the battery connected to the connection point can be designed as a high-voltage battery. The battery connected (switchably) to the connection point preferably has a nominal voltage of at least 400, 600 or 800 volts. The battery in the low-voltage onboard power supply preferably has a nominal voltage of substantially 12 to 14 volts, substantially 24 volts or substantially 48 volts.

[0028] A control device can be provided, which is connected to the first switch and the second switch in a controlled manner, wherein the control device can also be connected to the third, fourth and / or fifth switch in a controlled manner. In addition, the control device can be connected to the first converter and the second converter in a controlled manner. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 In order to explain the vehicle electrical system described here and its mode of operation in more detail. DETAILED DESCRIPTION

[0030] The vehicle electrical system FB shown is connected to an AC voltage source WQ and a DC voltage source GQ via a charging interface LS. The AC voltage source WQ and the DC voltage source GQ can be regarded as part of a charging station (outside the vehicle electrical system FB). The respective sources WQ, GQ are connected to the relevant charging terminals WA, GA of the vehicle electrical system FB via disconnect switches T1, T2. In particular, these sources WA, GA are connected to the AC voltage charging terminal WA of the vehicle electrical system and to the DC voltage charging terminal GA of the vehicle electrical system FB.

[0031] The vehicle electrical system FB comprises a battery AK, which is connected to a first DC voltage converter W1 via a first switch S1. The first DC voltage converter has two sides (a first side 1S and a second side 2S) which are galvanically isolated from one another. The vehicle electrical system FB further comprises a second switch S2. The second switch is also connected to the connection point VP, like the first switch S1. Furthermore, the battery AK is connected to the connection point VP via a third switch S3. A fourth switch S4 connects the DC voltage charging terminal GA to the connection point VP.

[0032] The detachable connection LV connects the third switch S3, via which the battery AK is connected to the connection point VP, to the connection point VP. The connection point VP is connected to the first side 1S of the first converter W1 via the first switch S1 and to the second side 2S of the first converter W1 via the second switch S2.

[0033] The second DC voltage converter W2 is connected to the first switch S1. In particular, the converter W2 is connected to one side of the first switch S1, in particular to the side of the first switch connected to the first side 1S of the first converter W1, or to the connection point VP, that is to say to the first side of the first switch S1, which is connected to the connection point VP. The last-mentioned connection is represented by a dotted line. The two possible connections are alternative to each other. The low-voltage on-board power supply branch NV is connected to the first side 1S of the first converter W1 or to the connection point VP (the battery is connected to the connection point via the third switch S3) via the second converter W2. The low-voltage on-board power supply branch NV (in addition to the second battery) can include at least one safety-related component, such as an electric steering drive or its control device, or an electric brake or its control device. The battery and the two sides of the first converter W1 are preferably constructed for high-voltage applications, in particular for a nominal voltage of at least 400 volts. Even if the second switch S2 is disconnected, for example in order to cut off a defective load, the low-voltage on-board power supply branch can also be supplied via the second converter W2 through the circuit shown.

[0034] The second switch S2 can connect the connection point VP with the first converter W1 or with its second side 2S. Alternatively (indicated by dotted lines), the second switch S2 can connect the battery AK with the first converter W1 or with its second side 2S. In this case, as indicated by dots, the second switch is not connected to the connection point VP.

[0035] The DC voltage charging terminal GA is connected to the connection point VP via the fourth switch S4. The DC voltage charging terminal GA is thus connected to the first side 1S of the first converter W1 via the fourth switch S4 and via the first switch S1. The AC voltage terminal WA is connected to the first side 1S of the first converter W1 via the fifth switch S5 and the rectifier device GR (and therefore also to the first switch S1).

[0036] In the embodiment shown, the second DC voltage converter W2 is designed to be multi-phase, in particular two-phase. In the specific example shown, the second converter W2 includes two single converters, which are connected to the low-voltage vehicle power supply branch NV. The configuration circuit KO connects the second converter W2 (or its single converter) to one side of the first switch S1. The configuration circuit KO is set up to connect the sides of the single converters connected to the first switch S1 to each other in parallel or in series in a switchable manner (and also connect these sides to the first switch). On the side of the low-voltage vehicle power supply branch NV2, the single converters of the second converter W2 are preferably connected in parallel to each other. The side of the second converter W2 connected to one side of the first switch S1 includes one or more intermediate circuit capacitors, and in the case of multiple single converters, includes multiple intermediate circuit capacitors. The intermediate circuit capacitors are also connected in series or in parallel with each other by means of the configuration circuit KO, especially because the intermediate circuit capacitors are connected in parallel to the respective input ends of the single converters.

[0037] In addition to the inverter I and the motor M, which are jointly part of the electric drive, the high-voltage component K is connected to the second side 2S of the first converter W1. It can be seen that the second converter W2 is not connected like such a load or component, but is connected to the first side 1S of the first converter. Therefore, the electric drive and the second converter are connected to two different opposite sides 1S, 2S of the first converter W1.

[0038] There may be a control device ST which is connected in a control manner to the first and second switches, preferably also to the third, fourth and fifth switches (if present). Furthermore, the control device ST may be connected in a control manner to the first converter W1 and the second converter W2 in order to at least set their activity state (inactive / active).

Claims

1. A vehicle electrical system (FB), comprising a DC voltage charging terminal (GA), a battery (AK), a first DC voltage converter (W1) and an electric drive (I, M), wherein the first DC voltage converter (W1) has a first side (1S), which is connected to a connection point (VP) via a first side of a first switch (S1), and the first DC voltage converter (W1) has a second side (2S), the electric drive (I, M) is connected to the second side, and the second side is connected to the battery (AK) via a second switch (S2) and via the connection point (VP) or the second side is directly connected to the battery (AK), wherein the vehicle electrical system comprises a second DC voltage converter (W2), which is connected to the first side of the first switch (S1) or directly to the connection point (VP). 2 . The vehicle onboard power supply system (FB) according to claim 1 , wherein the second DC voltage converter ( W2 ) is connected to a first side of the first DC voltage converter ( W1 ) or to the connection point (VP).

3. The vehicle onboard power supply (FB) according to claim 1 or 2, wherein the battery is connected to the connection point (VP) via a third switch (S3).

4. The vehicle onboard power system (FB) according to claim 1 or 2, wherein the first DC voltage converter and the second DC voltage converter (W1, W2) are each galvanically isolated DC voltage converters.

5. The vehicle onboard power system (FB) according to any one of claims 1 to 2, wherein a low-voltage onboard power system branch (NV) of the vehicle onboard power system (FB) is connected to one side of the first switch (S1) via the second DC voltage converter (W2).

6. The vehicle on-board power grid (FB) according to claim 5, wherein the second DC voltage converter (W2) has a high-voltage side and a low-voltage side, the high-voltage side is connected to one side of the first switch (S1), and the low-voltage side is connected to the low-voltage on-board power grid branch (NV).

7. The vehicle onboard power supply (FB) according to claim 1, wherein the DC voltage charging terminal (GA) is connected to the connection point (VP) via a fourth switch (S4).

8. The vehicle onboard power system (FB) according to any one of claims 1 to 2, comprising an AC voltage charging terminal (WA), which is connected to the first side (1S) of the first DC voltage converter (W1) via a rectifier device (GR) of the vehicle onboard power system (FB).

9. The vehicle onboard power supply (FB) according to claim 8, wherein the AC voltage charging terminal (WA) is connected to the rectifier device (GR) via a fifth switch (S5) and the rectifier device (GR) connects the fifth switch (S5) to the first side (1S) of the first DC voltage converter (W1). 10 . The vehicle onboard power supply system (FB) according to claim 8 , wherein the rectifier device is designed as a power factor correction filter.

11. The vehicle onboard power supply (FB) according to claim 3, wherein the third switch (S3) is connected to the connection point (VP) via a detachable connection (LV).

12. The vehicle onboard power system (FB) according to claim 3, wherein the battery (AK) and the third switch (S3) on the one hand and the first switch (S1), the second switch (S2), the first DC voltage converter (W1), and the second DC voltage converter (W2) on the other hand are arranged in different housings.

13. The vehicle onboard power system (FB) according to any one of claims 1 to 2, wherein the electric drive (I, M) is designed as a high-voltage component and at least one further high-voltage component (K) is connected to the second side (2S) of the first DC voltage converter (W1).

14. The vehicle on-board power system (FB) according to any one of claims 1 to 2, wherein the second DC voltage converter (W2) has a plurality of single converters, which are connected to one side of the first switch (S1) via a configuration circuit (KO), wherein the configuration circuit (KO) connects the single converters in series with each other in a first configuration state and connects the single converters in parallel with each other in a second configuration state.

15. The vehicle onboard power supply (FB) according to claim 14, wherein each single converter has an intermediate circuit capacitor, which is connected to one side of the first switch (S1) via the configuration circuit (KO), wherein the intermediate circuit capacitors are connected in series or in parallel with each other depending on the configuration state.

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