Vehicle electrical system having a redundantly supplied inverter

Abstract

The invention relates to a vehicle electrical system (100, 200, 300) which has a first vehicle electrical sub-system (101) with a first vehicle electrical sub-system voltage level, a second vehicle electrical sub-system (102) with a second vehicle electrical sub-system voltage level which is higher than the first vehicle electrical sub-system voltage level, a DC-DC converter (110, 210) which is connected to the first vehicle electrical sub-system (101) at a first terminal (111) and is connected to the second vehicle electrical sub-system (102) at a second terminal (112), and an inverter (10), wherein the inverter (10) has a first voltage supply terminal (11) which is configured such that a supply voltage having the first vehicle electrical sub-system voltage level is applied to said terminal in order to supply the supply voltage to control electronics of the inverter (10), and a second voltage supply terminal (12) which is configured such that a supply voltage having the first vehicle electrical sub-system voltage level is applied to said terminal in order to supply the supply voltage to the control electronics of the inverter (10), wherein the first voltage supply terminal (11) is connected to a first supply voltage source having the first vehicle electrical sub-system voltage level, and wherein the second voltage supply terminal (12) is connected to a second supply voltage source, which is different from the first, having the first vehicle electrical sub-system voltage level.

Description

[0001] Description

[0002] title

[0003] On-board electrical system with redundantly supplied inverter

[0004] The present invention relates to an on-board electrical system.

[0005] Background of the invention

[0006] Especially with so-called inverters (power converter devices or pulse inverters), which are used for the motor and generator operation of electric machines (also known as traction inverters), it must be ensured that no incorrect torque is generated. This is also necessary in the event of a fault, such as a power supply failure.

[0007] For this purpose, a redundant power supply for the control electronics (e.g., the processing unit such as an integrated circuit for controlling the power semiconductors of the power output stage) can be used to ensure a safe operating state of the electric drive even in the event of a power supply failure. A safe operating state for a synchronous machine is typically an active short circuit of the three machine windings. For this, the three lower switches or the three upper switches of the inverter's half-bridges can be actively controlled or switched to conduction. This requires electrical energy, which, in the event of a power supply failure, must be supplied to the inverter via a second redundant power supply.

[0008] For example, vehicles often use dual-voltage electrical systems, which consist of a low-voltage system (voltage less than the permissible touch voltage of 60 V, e.g., 12 V) and a high-voltage system (voltage greater than the permissible touch voltage, usually several hundred volts). The high-voltage and low-voltage systems can be connected by means of a DC-DC converter.

[0009] For example, the control electronics can be redundantly powered from both vehicle electrical systems, with the supply voltage corresponding to the low-voltage voltage. One power supply connection of the inverter can be connected to both the low-voltage electrical system and the DC-DC converter powered by the high-voltage electrical system. Alternatively, the inverter can also have an internal DC-DC converter and one power supply connection for the low-voltage electrical system and one for the high-voltage electrical system.

[0010] Disclosure of the invention

[0011] According to the invention, an on-board electrical system with the features of claim 1 is proposed. Advantageous embodiments are the subject of the dependent claims and the following description.

[0012] The invention is characterized by a redundant power supply for an inverter consisting of at least two supply voltage sources connected to separate power supply terminals of the inverter, thus avoiding a so-called "single point of failure" (SPOF). A redundant power supply for an inverter may be necessary for reasons of functional safety.

[0013] Specifically, the vehicle electrical system comprises a first sub-system with a first sub-system voltage level and a second sub-system with a second sub-system voltage level that is higher than the first sub-system voltage level. It also includes a DC-DC converter, which is connected to the first sub-system at one terminal and to the second sub-system at a second terminal, and an inverter. The first sub-system is typically a low-voltage system (voltage less than a permissible touch voltage of 60 V, e.g., 12 V), and the second sub-system is typically a high-voltage system (voltage greater than the permissible touch voltage, usually several hundred volts).

[0014] An inverter is a device used to convert a direct current (DC) voltage applied to a DC voltage terminal into an alternating current (AC) voltage applied to an AC voltage terminal, and vice versa if required, and which may have a power converter circuit with half-bridges and semiconductor switches for this purpose.

[0015] The inverter has a first voltage supply terminal configured to receive a supply voltage at the first sub-onboard voltage level to supply control electronics of the inverter, and a second voltage supply terminal configured to receive a supply voltage at the first sub-onboard voltage level to supply control electronics of the inverter, wherein the first voltage supply terminal is connected to a first supply voltage source at the first sub-onboard voltage level, and wherein the second voltage supply terminal is connected to a second supply voltage source at the first sub-onboard voltage level, different from the first.

[0016] The invention makes it possible to save costs, reduce the size of the device, and increase efficiency or reduce power losses. A redundant supply using the first partial on-board voltage level opens up new, more cost-effective possibilities for the inverter's internal power supply.

[0017] In one embodiment, the first supply voltage source is the first connection of the DC-DC converter. This is advantageous because it allows the inverter to be supplied from the second sub-electrical system. In another embodiment, the second supply voltage source is a battery, such as a conventional starter battery or a 12V battery. This is advantageous because it allows the inverter to be supplied directly with a suitable voltage level.

[0018] In one embodiment, the battery is connected to the first terminal of the DC-DC converter. This is advantageous because the battery can be charged via this connection.

[0019] In one embodiment, at least one separating element is provided between the first power supply terminal and the first terminal of the DC-DC converter, and / or between the second power supply terminal and the battery, and / or between the first terminal of the DC-DC converter and the battery.

[0020] In one embodiment, the vehicle electrical system is configured to open at least one isolating element if an overcurrent flows through it. This ensures the functional safety of the redundant power supply even in various fault conditions (short circuits).

[0021] An overcurrent is defined here as a current with an intensity exceeding a permissible threshold current. This prevents harmful currents in the vehicle's electrical system.

[0022] In one embodiment, the battery is not connected to the first terminal of the DC-DC converter. This eliminates the need for a isolating element between the two aforementioned supply voltage sources.

[0023] In one embodiment, the battery is connected to a third terminal of the DC-DC converter, which is configured to output a voltage at the first partial on-board voltage level. In this embodiment, the DC-DC converter can, in particular, have a second redundant terminal, and thus a third terminal for the first partial on-board voltage level, independent of the first terminal. This second redundant supply opens up new, more cost-effective possibilities for the inverter's internal power supply. A line break or short circuit does not result in the loss of both inverter supplies.

[0024] In one embodiment, the vehicle electrical system includes a second DC-DC converter, which is connected at a first terminal to a third sub-system and at a second terminal to the second sub-system, with the second supply voltage source being the first terminal of the second DC-DC converter. In this embodiment, two redundant and independent DC-DC converters can be provided. This second redundant supply offers new, more cost-effective options for the internal power supply of the inverter. A line break or short circuit does not result in the loss of both inverter supplies.

[0025] Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawing.

[0026] The invention is schematically illustrated in the drawing using exemplary embodiments and is described below with reference to the drawing.

[0027] Brief description of the drawings

[0028] Figure 1 shows an embodiment of an on-board power supply according to the invention with an inverter.

[0029] Figure 2 shows another embodiment of an on-board power supply according to the invention with the inverter.

[0030] Figure 3 schematically shows a DC / DC converter that can be used in the vehicle electrical system shown in Figure 2. Figure 4 shows another embodiment of a vehicle electrical system according to the invention with the inverter.

[0031] embodiment(s) of the invention

[0032] Figure 1 shows a schematic and circuit-diagram-like representation of a first embodiment of an on-board electrical system, designated as 100. The on-board electrical system 100 comprises a first sub-system 101 with a first sub-system voltage level UN and a second sub-system 102 with a second sub-system voltage level UH that is higher than the first sub-system voltage level UN. The first sub-system voltage level UN can be a low-voltage level, for example, with a nominal value of 12 V, and the second sub-system voltage level UH can be a high-voltage level, for example, with 800 V.

[0033] The on-board network 100 also has a DC voltage converter 110, which has a first connection 111 for the first sub-on-board network 101 and a second connection 112 for the second sub-on-board network 102 and is designed to transfer energy from the second sub-on-board network 102 to the first sub-on-board network 101.

[0034] The first sub-system 101 includes a battery 120, for example a typical starter battery in a vehicle.

[0035] Furthermore, the on-board network 100 has an inverter 10, which has a first voltage supply connection 11 and a second voltage supply connection 12.

[0036] An inverter, such as inverter 10, is a device used to convert a direct current (DC) voltage applied to a DC voltage terminal 13 into an alternating current (AC) voltage applied to an AC voltage terminal 14, and vice versa if required. It may incorporate a power converter circuit with half-bridges and semiconductor switches. For example, the second sub-system 102 can be connected to the DC voltage terminal 13, and an electric machine 20, which can be used, for example, as a drive system or for power assistance in a vehicle, can be connected to the AC voltage terminal 14.

[0037] The two power supply connections 11 and 12 are designed to receive a supply voltage with the first partial on-board voltage level UN and to supply control electronics of the inverter, e.g. computing unit(s) such as integrated circuit(s) for controlling the semiconductor switches of the half-bridges.

[0038] Connections 11 to 14 are led out of a device housing of the inverter 10.

[0039] The first power supply terminal 11 is connected to a first supply voltage source with the first sub-board voltage level, and the second power supply terminal 12 is connected to a second supply voltage source different from the first with the first sub-board voltage level.

[0040] In the on-board network 100, specifically both the first voltage supply connection 11 and the second voltage supply connection 12 are connected to the first connection 111 as the first supply voltage source and the battery 120 as the second supply voltage source and can be supplied with voltage from both supply voltage sources.

[0041] Additionally, three isolating elements 131, 132, and 133 are provided, wherein a first isolating element 131 is provided between the first power supply terminal 11 and the first terminal 111 of the DC-DC converter 110, a second isolating element 132 is provided between the second power supply terminal 12 and the battery 120, and a third isolating element 133 is provided between the first terminal 111 of the DC-DC converter 110 and the battery 120. The isolating elements 131 to 133 can, for example, be designed as fuses that open in the event of an overcurrent. An overcurrent is defined here as a current with a current intensity that exceeds a permissible threshold current intensity.

[0042] For example, a short circuit of the first power supply terminal 11 to ground triggers the first disconnecting element 131 and the inverter 10 continues to be supplied with energy via the second power supply terminal 12.

[0043] For example, a short circuit of the second power supply terminal 12 to ground triggers at least the second isolating element 132, but not the first isolating element 131, and the inverter is supplied via the first power supply terminal 11.

[0044] For example, a short circuit of the first terminal 111 of the DC-DC converter 110 triggers the third isolating element 133 (and possibly an internal fuse of the DC-DC converter 110) and the inverter 10 is supplied via the second voltage supply terminal 12.

[0045] For example, a short circuit of battery 120 to ground triggers the third disconnect element 133 and the inverter 10 is supplied via the first voltage supply connection 11.

[0046] A break in the line at any point in the first sub-network 101 does not lead to a loss of voltage supply to the inverter 10.

[0047] Figure 2 shows a further embodiment of a proposed vehicle electrical system schematically and in the form of a circuit diagram, and is designated as 200 in its entirety. Identical elements in the figures are provided with the same reference numerals.

[0048] In contrast to embodiment 100 according to Figure 1, an alternative embodiment 210 of a DC-DC converter is provided, which, in addition to the first and second terminals, has a third terminal 211, which is also configured to output a voltage at the low-voltage level UN. In this embodiment, the first voltage supply terminal 11 of the inverter 10 is connected via the first sub-system 101 only to the first terminal 111 as the first supply voltage source, but no longer to the battery 120.

[0049] The second power supply terminal 12 of the inverter 10 is no longer connected to the first terminal 111 and no longer to the first sub-network 101, but to a third sub-network 103 with the low-voltage level UN. The second power supply terminal 12 of the inverter 10 is connected to the battery 120 and to the third terminal 211 of the DC-DC converter 210 as the second supply voltage sources.

[0050] This separate connection eliminates the need for the separating elements 131 to 133 shown in Figure 1.

[0051] A functional internal structure of the DC-DC converter 210 is shown schematically in Figure 3. In particular, the DC-DC converter 210 has two separate converter stages 214, 215, which supply the first terminal 111 and the third terminal 211 separately and are controlled by a control electronics unit 213.

[0052] This can be illustrated by a DC-DC converter 210, which has two sub-converters with two independent converter stages 214, 215 and a common control circuit. If one of the two converter stages of the DC-DC converter 210 fails, the failed converter stage can short-circuit at most one of the two sub-networks 101, 103 to ground. The DC-DC converter 210 can continue to supply inverter 10 via the other converter stage. If the common control circuit 213 of the DC-DC converter 210 fails, both converter stages can no longer supply power. However, the two converter stages can then no longer create short circuits to ground. Inverter 10 can then be supplied via battery 120. This approach can also be implemented for a DC-DC converter consisting of more than two sub-converters.This redundant power supply eliminates the need for a redundant internal inverter supply from the DC voltage connection 13 (which can be at the second sub-system voltage level UH or high-voltage level), resulting in a significant simplification of the first sub-system 101. A line break or short circuit at any point in the first sub-system 101 or in the third sub-system 103 does not lead to a loss of power supply to the inverter 10.

[0053] Figure 4 shows a further embodiment of a proposed on-board power supply schematically and in circuit diagram form, and is designated collectively as 300. The on-board power supply 300 has two redundant and independent DC-DC converters 110, 110', wherein the first terminal 111 of a first DC-DC converter 110 of the two DC-DC converters is connected to the first voltage supply terminal 11 of the inverter 10, and a first terminal 11T of a second DC-DC converter 110' of the two DC-DC converters is connected to the second voltage supply terminal 12 of the inverter 10. For example, the two DC-DC converters 110, 110' can be operated on different sub-batteries of the high-voltage supply.

[0054] This redundant power supply eliminates the need for a redundant internal inverter supply from the DC connection 13 (which can be at the second sub-system voltage level UH or high-voltage level), resulting in a significant simplification of the first sub-system 101 and the third sub-system 103. A line break or short circuit at any point in the first sub-system 101 or the third sub-system 103 does not lead to a loss of power supply to the inverter 10.

Claims

Claims 1. On-board electrical system (100, 200, 300), comprising - a first partial on-board network (101) with a first partial on-board voltage level, - a second sub-network (102) with a second sub-network voltage level that is higher than the first sub-network voltage level, - a DC / DC converter (110, 210) which is connected at a first terminal (111) to the first sub-system (101) and at a second terminal (112) to the second sub-system (102), and - an inverter (10), wherein the inverter (10) has: -- a first power supply terminal (11) configured to receive a supply voltage at the first partial on-board voltage level to supply control electronics of the inverter (10) with the supply voltage; and -- a second power supply terminal (12) configured to receive a supply voltage at the first sub-onboard voltage level to supply the control electronics of the inverter (10) with the supply voltage; wherein the first power supply terminal (11) is connected to a first supply voltage source at the first sub-onboard voltage level, and wherein the second power supply terminal (12) is connected to a second supply voltage source at the first sub-onboard voltage level, different from the first.

2. On-board power supply (100, 200, 300) according to claim 1, wherein the first supply voltage source is the first terminal (111 , 11 T) of the DC voltage converter (110, 210).

3. On-board electrical system (100, 200, 300) according to claim 1 or 2, wherein the second supply voltage source is a battery (120).

4. On-board electrical system (100, 200, 300) according to claims 2 and 3, wherein the battery (120) is connected to the first terminal (111) of the DC voltage converter (110).

5. On-board power supply (100, 200, 300) according to claim 4, wherein at least one separating element (131, 132, 133) is provided: - between the first power supply terminal (11) and the first terminal (111) of the DC-DC converter (110), and / or - between the second power supply terminal (12) and the battery (120), and / or - between the first terminal (111) of the DC-DC converter (110) and the battery (120).

6. On-board network (100, 200, 300) according to claim 5, which is configured to open the at least one separating element (131 , 132, 133) when an overcurrent flows through the at least one separating element (131, 132, 133).

7. On-board electrical system (100, 200, 300) according to claims 2 and 3, wherein the battery (120) is not connected to the first terminal (111) of the DC voltage converter (110).

8. On-board electrical system (100, 200, 300) according to claim 7, wherein the battery (120) is connected to a third terminal (211) of the DC-DC converter (110, 210), wherein the third terminal (211) of the first DC-DC converter (110, 210) is configured to output a voltage at the first partial on-board voltage level.

9. On-board electrical system (100, 200, 300) according to claim 1 or 2, comprising a second DC-DC converter (110') connected to a first terminal (11 T) is connected to a third sub-network (103) and to a second terminal (112) is connected to the second sub-network (102), wherein the second supply voltage source is the first terminal (11 T) of the second DC voltage converter (110').

Images