Vehicle electrical system

Abstract

A vehicle electrical system (FB) is equipped with a DC charging terminal (GA), a battery (AK), a DC voltage converter (W1) and an electric drive (I, M). The DC voltage converter (GW) has a first side (1S), which is connected to a connection point (VP) via a first switching device (S1, D). The DC voltage converter (GW) has a second side (2S), the electric drive (I, M) is connected to the second side, and the second side is connected to a connection point (VP) via a second switching device (S2, S3). The connection point (VP) is connected to the battery (AK). The DC charging terminal (GA) is connected to the side of the first switching device (S1, D) connected to the first side (1S) of the DC voltage converter (GW).

Description

Technical Field

[0001] The invention relates to a vehicle electrical system. Background Art

[0002] Vehicles with an electric drive have a battery which, in the case of plug-in vehicles, can be charged externally by means of a charging terminal. In addition, components with a nominal voltage of, for example, 800 volts are present within the vehicle (e.g., a high-voltage battery), while a different voltage of 400 volts can be set at the charging input, depending on the charging station. Therefore, there are multiple segments within the electrical system which have different nominal voltages but are directly or indirectly connected to the battery. Summary of the invention

[0003] Furthermore, the object of the present invention is to demonstrate a possibility with which a vehicle electrical system can be designed in such a way that, on the one hand, different nominal voltages within the vehicle electrical system are possible and, on the other hand, the vehicle can be charged and driven in a manner that is protected from excessively high contact voltages despite different nominal voltages in segments of the vehicle electrical system.

[0004] This task is solved by the vehicle electrical system.

[0005] Further embodiments, features, characteristics and advantages emerge from the further examples, descriptions and figures.

[0006] A vehicle electrical system is proposed, which has a DC charging terminal, a battery, a DC voltage converter and an electric drive. The DC voltage converter has a first side and a second side, wherein the first side is connected to a connection point via a first switching device. The second side of the DC voltage converter is connected to the electric drive and is also connected to the connection point via a second switching device. The connection point is used to couple the battery. The battery is connected to the connection point (especially via an isolating device and / or via a fuse). The DC charging terminal is connected to one side of the switching device, wherein the side is connected to the first side of the DC voltage converter. Therefore, the DC charging terminal is connected to the first side of the DC voltage converter and is especially (related to this) connected to this side of the switching device. In other words, the DC charging terminal is connected to the connection point via the first switching device and is therefore connected to the battery. Therefore, starting from the battery, two different paths are obtained, which are gathered through the connection point, wherein different paths lead to different sides of the DC voltage converter. One of the two switching devices is arranged in each path.

[0007] As a result, the DC charging terminal can be disconnected from the battery by means of the switching device. The electric drive can also be disconnected from the battery by means of the switching device (i.e. the second switching device). Thus, the possibility of isolating the battery is obtained both for driving and for charging, so that high contact voltages can be avoided. In particular, this operating method allows high voltages stored in the electric drive (e.g. the voltage of the intermediate circuit) to be isolated by means of the switching device, so that high contact voltages can be avoided.

[0008] The first switching device is bipolar and comprises a diode device for one potential of the vehicle electrical system and a switching element for another potential of the vehicle electrical system. The diode device and the switching element are connected in series and enable the current flow to be interrupted. The switching element is in particular an electromechanical switching element or also a semiconductor switch. The first switching direction connects the two potentials of the first side of the DC voltage converter to the two potentials of the connection point. The two potentials are, for example, a negative potential and a positive potential or a positive potential and a ground potential. The switching device sets the switching element for one of the potentials. The switching device sets the diode device for the other potential. As mentioned, the switching element and the diode device are connected in series. The conduction direction of the diode device preferably corresponds to the current flow direction of the charging current, by means of which the electrical energy is directed from the DC charging terminal to the battery. If the diode device is at a positive potential, the conduction direction leads from the DC charging terminal to the connection point or the battery. If the diode device is at a negative potential or a ground potential, the conduction direction is away from the connection point or the battery and points to the DC charging terminal. The potentials are respectively DC voltage potentials. A DC voltage is applied between the potentials. In particular, each potential is respectively assigned to a (direct current) busbar, which can also be referred to as a DC busbar or a direct current conductor. The potentials are in particular direct current voltage potentials. A supply voltage, in particular a high-voltage supply voltage, is applied between the potentials. The potentials are in particular high-voltage potentials.

[0009] The diode device is preferably a power diode device. The diode device has the function of a diode, but does not necessarily have to be realized by a single diode, but may have other diodes, or may have other devices that realize the function of a diode.

[0010] The diode device preferably connects the positive potential of the first side of the DC voltage converter to the potential of the connection point (or the battery). The conduction direction of the diode device points from the first side of the DC voltage converter to the connection point. Alternatively, the diode device connects the negative potential of the first side of the DC voltage converter to the negative potential of the connection point (or the battery). In this case, the conduction direction of the diode device points from the connection point (or from the battery) to the first side of the DC voltage converter.

[0011] The diode device is preferably a semiconductor device. The diode device may correspond to a diode. In addition, the diode device may have at least one diode. If the diode device has a plurality of diodes, these diodes may be connected in parallel or in series with each other, but preferably all have the same conduction direction. The diodes of the diode device are connected in series. Alternatively, the diode device has a transistor or another semiconductor element, wherein the transistor or semiconductor element is controlled by its wiring so that the diode device (diese) performs the function of a diode. This is particularly related to devices that can be controlled by external switching signals, wherein these devices realize the function of a diode by corresponding control and / or wiring. These devices are also considered to be diode devices.

[0012] The second switching device connects the two potentials of the second side of the DC voltage converter to the two potentials of the connection point. In this case, the switching device connects the first potential of the second side to the first potential of the connection point by means of a first switchable connection, and connects the second potential of the second side to the second potential of the connection point by means of a second switchable connection. Thus, the second switching device connects the potentials individually. The switching device has a switching element for each potential. The switching element can be configured as an electromechanical switching element or as a semiconductor switching element, for example as a transistor. In particular, the two switching elements are formed by contacts of a double relay.

[0013] Furthermore, it can be provided that the connection point is connected to the battery via a pyro fuse. A pyro fuse is an electrical connection that can be disconnected by means of an explosive. The explosive is triggered by an electrical igniter. Upon triggering, the explosive mechanically separates the electrical connection. The pyro fuse is preferably connected in series at the same potential at which the diode device is also located.

[0014] A control device can be provided in the sense of a control device, which is configured to control the switching device or disconnect the switching device according to the open circuit state. The control device is also configured to trigger the high-temperature fuse device only when at least one of the switching devices is not disconnected despite the corresponding control or only when a high potential or high voltage is determined despite the corresponding control. For this purpose, the control device is connected to the switching device and the high-temperature fuse device in a controllable manner. In particular, the control device is configured to first operate the switching device and then, after checking the effect of the disconnection of the switching device, if a high potential can be determined despite the disconnection (on the side of the high-temperature fuse device facing away from the battery), the high-temperature fuse device is triggered.

[0015] The connection point can be connected to the battery via a release device (Freischalteinrichtung). For example, during maintenance, the release device can be used to switch a segment of the vehicle electrical system to a voltage-free state. The release device is connected in series at the same potential at which the diode device is also located. In particular, the release device is at the same potential as the high-temperature fuse device (or in the same busbar). The release device can be present between the high-temperature fuse device and the battery. In addition, the high-temperature fuse device can be present between the release device and the battery. Not only the high-temperature fuse device but also the release device, if present, is preferably only arranged at one of the two potentials (in particular, the potential at which the diode device is also located), while the other potential is transmitted through a direct connection between the connection point and the battery.

[0016] The release device can be a power switch, a circuit breaker, a fuse, a load disconnect switch, a fault current switch or a plug-in device with a disconnect function. Preferably, the release device is a detachable jumper. If the jumper is removed from the bracket, the two contacts are separated from each other, and when the jumper is plugged in, the two contacts are connected to each other by the jumper.

[0017] The second switching device is preferably designed as a double relay.

[0018] In addition, an AC charging terminal can be provided, which is connected to the first side of the DC voltage converter via a rectifier. A further switching device can be provided, which is arranged between the first side of the DC voltage converter and the first switching device. The DC charging terminal can be connected directly to the first switching device or can be connected to the first switching device via a further switching device. The DC charging terminal can be connected directly to the first switching device and / or can be connected directly to the first side of the DC voltage converter.

[0019] A further DC voltage converter (hereinafter: additional converter) may be provided. The further DC voltage converter may have a first side, which is connected to the first side of the DC voltage converter. The second side of the additional converter may be connected to a low-voltage electrical system, for example an electrical system segment having a terminal voltage of approximately 12, 13, 14, 24 or 48 volts.

[0020] Other electrical components can be provided, which are connected to the second side of the DC voltage converter. In this case, this can be, for example, an electric heating device of a heating device, in particular a catalytic converter, or an air conditioning device, such as an electric air conditioning compressor or an electric interior space heating element. Other switches can be provided between the second side of the DC voltage converter and the electric drive. Other components can be directly connected to the second side, and the electric drive is connected to the second side via the switch. The switch can be constructed as a semiconductor fuse, in particular as an IGBT, with a diode connected in parallel to the IGBT. In the event of a fault, the semiconductor fuse is disconnected by a control signal. The flow direction of the diode is preferably directed from the second side of the DC voltage converter to the second switching device. This is particularly applicable if the switch is set at a positive potential; if the switch is connected in series in a negative potential, the diode has an opposite flow direction.

[0021] The battery and the release device, the battery and the high-temperature fuse device, or the battery, the release device, and the high-temperature fuse device may be arranged in one housing, while the remaining components of the vehicle electrical system are arranged in at least one other housing.

[0022] The vehicle electrical system is preferably a high-voltage electrical system with a nominal voltage of at least 60 volts, 100 volts, 200 volts, 400 volts or 800 volts (at least in sections). The battery is preferably a traction battery, in particular a high-voltage battery. The battery can be a lithium battery. The battery has a nominal voltage of, for example, 400 volts or 800 volts. The rectifier between the AC charging terminal and the first side of the DC voltage converter can be an uncontrolled rectifier, a controlled rectifier or a power factor correction filter. In addition, other voltage converters can be arranged between the rectifier and the DC voltage converter. A filter can be arranged between the first side of the DC voltage converter and the first switching device. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 For illustrating embodiments of the vehicle electrical system described herein. DETAILED DESCRIPTION

[0024] Figure 1 The vehicle electrical system FB is shown, which has a DC charging terminal GA, a battery AK, a DC voltage converter W1 and an electric drive having an inverter I and an electric machine M. The battery has a negative pole, which is directly connected to the connection point or the corresponding negative potential N of the connection point VP. The positive pole of the battery AK is connected to the positive potential P of the connection point VP via a release device FE and a pyrofuse fuse. Two paths originate from the connection point VP.

[0025] The first path from the connection point VP leads from the connection point VP via the first switching device (including the switch S1 in the negative current path and the diode D in the positive current path) and via the switch SD (omnipolar, i.e. in the negative current path and the positive current path) to the first side 1S of the DC voltage converter W1. In this case, the DC charging terminal GA is connected to the connection point VP via the switching device DS1. The switch SD is connected in series with the first switching device.

[0026] The second path from the connection point VP leads via the second (all-pole) switching means S2, S3 and the (all-pole) additional switch SC to the second side 2S of the DC voltage converter W1. The paths from the connection point VP are brought together at the DC voltage converter W1.

[0027] The optional AC charging terminal WA is connected to the rectifier GR via the isolating switch SW, which in turn is connected to the first side 1S of the DC voltage converter W1. The DC voltage converter GR is directly connected to the first side 1S of the DC voltage converter W1. The additional switch SD connects the first side of the DC voltage converter and thus also the DC side of the rectifier GR to the first switching device S1, D on the one hand and to the DC charging terminal GA on the other hand. An alternative position POS is shown, to which the DC charging terminal GA is connected in an alternative embodiment. The DC charging terminal (dieser) is located between the switch SD and the first side 1S of the DC voltage converter W1. However, in the example shown, the DC charging terminal GA and the AC charging terminal WA or its rectifier GR are located on different sides of the switch SD.

[0028] The second side 2S of the DC voltage converter W1 is directly connected to the component K shown by way of example. The additional switch SC connects this component and thus also the second side 2S of the converter W1 to the second switching devices S2, S3. The electric drive and in particular its inverter I are connected to the side of the additional switch SC connected to the second switching devices S2, S3. The component K (e.g. an 800 volt component, such as an electric heater or an air conditioning compressor) is connected to the side of the additional switch SC connected to the second side 2S of the DC voltage converter W1. The switch denoted by SC can have the function of a semiconductor fuse, i.e. a semiconductor-based disconnecting switch that opens in the event of an overcurrent.

[0029] The first switching device comprises a first switch S1 and a diode D. The first switch S1 is set at a negative potential N, while the diode D is set at a positive potential in series. The diode D thus connects the positive potential of the DC terminal to the positive potential of the connection point or the battery. The first switch S1 connects the negative potential of the DC terminal GA to the connection point VP or the negative potential of the battery AK.

[0030] The second switching device includes a second switch S2 and a third switch S3, wherein the third switch S2 is set at a negative potential (in series), and the third switch is set at a positive potential. In other words, the switch S1 and the switch S2 are located in the negative busbar of the vehicle electrical system. The diode D is located in the positive busbar of the connected electrical system (Verbindungsbordnetz). This also applies to the third switch S3. Compared with the two-pole switching unit composed of switches S2 and S3, the first switching device also includes a diode D in addition to the switching element S1 (first switch), that is, a component with a cut-off direction and a conduction direction, wherein the current flow (Stromfluss) is predetermined by the direction of the current, not by an external control signal. Two voltage rails or potentials N, P are shown separately on the right side of the vehicle electrical system shown. From the battery, on the opposite side (jenseits) of the second switching device or the opposite side of the switch SD, for simplicity, only the basic connection is shown, and the individual potentials are not shown. Therefore, even if the connection is only represented by a separate line on the left side of the figure, the connection also includes a positive busbar and a negative busbar or two potentials (positive potential and negative potential P, N).

[0031] The control device ST is connected to the switches S1, S2 and S3 in an actuating manner and can also be connected to the switches SC and SD and, if necessary, to the switch SW in an actuating manner. This actuating connection is symbolically reproduced by a double arrow. The control device ST is also connected to the high-temperature fuse device in an actuating manner in order to trigger the high-temperature fuse device if necessary. The control device ST is designed to first disconnect the switches S1, S2 and S3 and, if necessary, also the switches SD, SC and SW, and only trigger the high-temperature fuse device if a high voltage can be detected, for example, at the DC charging terminal GA or at the AC charging terminal WA or at other points in the vehicle electrical system, although no high voltage is expected there according to the switch actuation. In the event of a fault, the control device disconnects the corresponding switch or fuse device.

[0032] The vehicle electrical system comprises terminals WA and GA for charging, wherein the terminals form a charging interface LS. External energy sources WQ and GQ are designed to be connected to these terminals WA, GA and can be provided as external energy sources by a charging station, for example.

Claims

1. A vehicle electrical system (FB), comprising a DC charging terminal (GA), a battery (AK), a DC voltage converter (W1) and an electric drive (I, M), wherein the DC voltage converter (W1) has a first side (1S) which is connected to a connection point (VP) via a first switching device, wherein the first switching device comprises a switching element (S1) and a diode device (D), and the DC voltage converter (W1) has a second side (2S) to which the electric drive (I, M) is connected, and the second side is connected to the connection point (VP) via a second switching device (S2, S3), wherein the connection point (VP) is connected to the battery (AK) and the DC charging terminal (GA) is connected to a side of the first switching device which is connected to the first side (1S) of the DC voltage converter (W1); and An additional converter is provided with a first side which is connected to the first side of the DC voltage converter, wherein the DC charging terminal can be disconnected from the battery by means of the first switching device and wherein the electric drive can be disconnected from the battery by means of the second switching device.

2. A vehicle electrical system (FB) according to claim 1, wherein the first switching device connects two potentials of the first side (1S) of the DC voltage converter (W1) to two potentials of the connection point (VP), wherein the first switching device sets a switching element (S1) for one of the potentials and sets a diode device (D) for the other potential, the conduction direction of the diode device corresponding to the current flow direction of the charging current, with the aid of which electrical energy is conducted from the DC charging terminal (GA) to the battery (AK).

3. The vehicle electrical system (FB) according to claim 2, wherein the diode device (D) connects the positive potential of the first side (1S) of the DC voltage converter (W1) to the positive potential of the connection point (VP), and the conduction direction of the diode device (D) is from the first side (1S) of the DC voltage converter (W1) to the connection point (VP), or The diode device (D) connects the negative potential of the first side (1S) of the DC voltage converter (W1) to the negative potential of the connection point (VP), and the conduction direction of the diode device (D) points from the connection point (VP) to the first side (1S) of the DC voltage converter (W1).

4. The vehicle electrical system (FB) according to claim 2 or 3, wherein the diode device (D) corresponds to a diode connected in series, or comprises a transistor which is controlled via its wiring such that it performs the function of a diode.

5. A vehicle electrical system (FB) according to any one of claims 1 to 3, wherein the second switching device connects the two potentials of the second side (2S) of the DC voltage converter (W1) to the two potentials of the connection point, wherein the second switching device sets a switching element for each potential.

6. A vehicle electrical system (FB) according to any one of claims 2 to 3, wherein the connection point (VP) is connected to the battery (AK) via a high-temperature fuse (PF), wherein the high-temperature fuse (PF) is connected in series at the same potential as the diode device (D).

7. The vehicle electrical system (FB) according to claim 6 further comprises a control device (ST), which is configured to control the first switching device and the second switching device according to an open circuit state and is further configured to trigger the high-temperature fuse device (PF) only when at least one of the first switching device and the second switching device has not been disconnected despite corresponding control.

8. A vehicle electrical system (FB) according to any one of claims 2 to 3, wherein the connection point (VP) is connected to the battery (AK) via a release device (FE), wherein the release device (FE) is connected in series at the same potential as the diode device (D).

9. The vehicle electrical system (FB) according to claim 8, wherein the release device is a power switch, a circuit breaker, a fuse, a load isolation switch, a fault current switch or a plug-in device with a separation function.

10. The vehicle electrical system (FB) according to claim 8, wherein the release device is a detachable jumper.

11. The vehicle electrical system according to any one of claims 1 to 3, wherein the second switching device (S2, S3) is designed as a double relay.

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