EP2909910A1

EP2909910A1 - Protection circuit arrangement for a multi-voltage power supply

Info

Publication number: EP2909910A1
Application number: EP13766046.0A
Authority: EP
Inventors: Sebastian WALENTA; Ulf Pischke; Nils Draese; Juergen Haeffner; Turgut Karacay; Gabriel Wetzel; Mirko Schinzel
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2012-10-17
Filing date: 2013-09-20
Publication date: 2015-08-26
Also published as: WO2014060181A1; CN104704698B; US20150288169A1; US9893511B2; DE102012218914A1; CN104704698A

Abstract

A protection circuit arrangement for a multi-voltage power supply is presented. It comprises a DC-DC converter (102), which is provided in the region of transition between a high-voltage loop (110) and a low-voltage loop (112), at least one switch being provided in both the high-voltage loop and in the low-voltage loop.

Description

Description title

Protective circuit arrangement for a multi-voltage network

The invention relates to a protective circuit arrangement for a multi-voltage network, for example in a motor vehicle in order to control internal and possibly external faults, in particular short circuits and reverse polarity. The protective circuit arrangement may be at least partially part of a DC-DC converter as well as provided separately in the multi-voltage network.

State of the art

DC-DC converters are used to convert different voltages. As a DC-DC converter, an electrical circuit or an electrical component is regularly referred to, which converts a DC voltage supplied to the input to another DC voltage.

DC voltage converters are used, for example, in so-called multi-voltage networks, in which a primary-side input voltage, based on the converter, is converted into a comparatively high or low secondary-side output voltage. Under a multi-voltage network networks are referred to with multiple meshes, which are operated with different electrical voltages. In the interaction of the different meshes, it is necessary to convert the electrical voltage between them.

Multi-voltage networks are found in motor vehicles as electrical power supply systems, which in addition to the usually set to a DC voltage of 12V low-voltage loads with at least one example set to 48V high-power load. For this purpose, the multi-voltage network has a corresponding high-power generator and / or a corresponding high-performance battery and a DC-DC converter, which converts the DC voltage, which is, for example, 48V, with approximately the same power in a 12V voltage. Typically, the multi-voltage network of a motor vehicle usually also has a low-voltage battery, for example a 12V battery.

In motor vehicles, DC-DC converters are used, for example, in a low-voltage hybrid system. In this application, the DC-DC converter transfers the energy between the 48V and 12V on-board networks. The 48V vehicle electrical system is a high-voltage mesh, the 12V

Wiring system a low voltage mesh. Such a DC-DC converter is referred to as PCU-BRS (Power Conversion Unit for Boost Recuperation System). A challenge of this converter is to protect the 12V electrical system. This must be ensured even in the case of a short circuit from the high-voltage side to ground and a Durchlegierens the half-bridges. It is known for such a protection circuit a fuse, for example. A

Semiconductor switch to provide on the 12V side.

From the document DE 10 2008 041 341 A1 a DC-DC converter is known, which is used in a vehicle electrical system of a motor vehicle. In the described DC-DC converter, the external ground potential is separated from an internal ground potential point when the DC-DC converter is in the off state. In this way, parasitic current flows are largely avoided.

Disclosure of the invention

Against this background, a protective circuit arrangement for a multi-voltage network according to claim 1 is presented. Embodiments result from the dependent claims and the description. It is proposed to provide at least one switch both on the low-voltage side or in the low-voltage mesh as well as on the high-voltage side or in the high-voltage mesh. So far, a circuit is provided on the low voltage side. In order to provide optimum protection, in one embodiment the switch on the high voltage side is designed with different trigger conditions than the switch on the low voltage side.

This cost-effective, but also very effective solution makes galvanically non-isolated DC-DC converters interesting. There is optimal protection, almost as with galvanically isolated converters at a lower cost.

The presented protective circuit arrangement is used, for example, in a motor vehicle, in particular in a recuperation system in the motor vehicle. This is used for energy recovery and leads to a reduction of exhaust gases. It should be noted that in the automotive vehicle, the voltage on the low voltage side is regularly in a range of 9 to 16V. The voltage on the high voltage side can be up to 600V. Such a high voltage is needed, for example, in hybrid vehicles.

On the two sides and two switches can be provided, which usually lock in different directions. Usually, the first of the two switches protects against internal errors, i. H. Malfunction in the DC-DC converter, and the second switch against external errors, such as. A reverse polarity or a short circuit.

It should also be noted that switches are usually formed by a number of parallel transistors, for example MOSFET transistors, so that high currents can be efficiently conducted and reliably switched off in this way.

Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawings.

It is understood that the features mentioned above and those yet to be explained not only in the combination specified in each case, but which can be used in other combinations or alone, without departing from the scope of the present invention.

Brief description of the drawings

FIG. 1 shows an embodiment of a multi-voltage network.

FIG. 2 shows an embodiment of the described circuit arrangement in a multi-voltage network.

FIG. 3 shows a further embodiment of the described circuit arrangement in a multi-voltage network.

FIG. 4 shows yet another embodiment of the described circuit arrangement in a multi-voltage network.

Figure 5 illustrates in a schematic representation different triggering conditions.

Embodiments of the invention

The invention is schematically illustrated by means of embodiments in the drawings and will be described in detail below with reference to the drawings.

Figure 1 shows an embodiment of a multi-voltage network, which is generally designated by the reference numeral 10. This multi-voltage network comprises a high-voltage mesh 12 and a low-voltage mesh 14, between which a DC-DC converter 16 is connected. This converts the voltage between the two meshes 12 and 14. Furthermore, a load 18 and a source 20 are provided in the high-voltage mesh 12. The low-voltage mesh 14 comprises a consumer 22 and a source 24. In principle, a consumer or an energy source, for example a battery, may be provided in each of the two meshes 12 and 14, respectively. An error in the DC-DC converter 16 now leads to a malfunction of the entire multi-voltage network 10. When used in a motor vehicle, this can lead to a failure of certain function and thus safety-critical driving conditions. Therefore, it must be ensured that errors in the DC-DC converter 16, ie internal errors, and preferably also external faults, such as a short circuit or reverse polarity in the multi-voltage network 10, are detected and timely measures can be taken to ensure safe further operation of the motor vehicle , FIG. 2 shows an embodiment of the protective circuit arrangement, designated overall by the reference numeral 50. This circuit arrangement 50 comprises a DC-DC converter 52 which is provided in the region between a high-voltage mesh 54 and a low-voltage mesh 56, ie in this embodiment that the DC-DC converter 52 respectively comprises parts of the two meshes 54 and 56.

The DC-DC converter has a microcontroller 61 as a controller, a module with the circuit inductances 62 and a power or switching part 64. In the power section 64, a number of branches 66 are provided corresponding to the number of phases. Each phase consists of a half-bridge with two transistors or switches with an upper half-bridge 68 and a lower half-bridge 69. On the high-voltage side, a switch 72 with a source 74 and a motor 76 parallel to it are provided at terminal 60 (reference numeral 70). In the low-voltage mesh 56, a source 80, a first consumer 82, a second consumer 84 and an additional consumer 86 are connected in parallel with each other.

In the DC voltage converter 52, a first switch 90 is provided in the high-voltage mesh 54 and a second switch 92 is provided in the ground path and thus in the low-voltage mesh 56.

With the two switches 90 and 92 can be responded to different errors suitable. On a short circuit between the high voltage and ground, for example. Externally in the wiring harness or internally in the circuit itself, the first switch 90 is opened. If there is a short circuit between the low voltage and earth, for example, externally in the wiring harness or internally in the circuit itself, the second switch 92 is opened.

A short circuit between high and low voltage can be externally caused by a short circuit in the wiring harness. In this case, no countermeasure is required. If this short circuit is due to an internal short circuit, the switches 90 and 92 are opened.

FIG. 3 shows a further embodiment of the circuit arrangement 100 with a DC-DC converter 102 having a first phase 104, a second phase 106 and a third phase 108. This DC-DC converter 102 is arranged between a high-voltage mesh 110 and a low-voltage mesh 12, wherein parts of the two meshes 1 10 and 1 12 are integrated in the DC-DC converter 102.

The high-voltage mesh includes u. a. a switch 120 and a source 122 in series connected in parallel with an electric machine 124. In the low-voltage mesh 1 12, a source 130, a first consumer 132, a second consumer 134 and another consumer 136, for example, the electric machine 124 are arranged parallel to each other.

In the DC-DC converter 102 on the high-voltage side and thus in the high-voltage mesh 1 10, a first switch 140 and a second switch 142 is arranged. This so-called back-to-back arrangement (B2B) is formed by means of two oppositely arranged MOSFETs. Outside the DC-DC converter 102 in the ground path and thus in the low-voltage mesh 1 12, a third switch 144 and a fourth switch 146 are provided, which form a zweitet B2B.

The first switch 140 protects against an internal fault, for example when the upper half-bridge switch 150 of the DC-DC converter 102 breaks down. The second switch 142 protects against an external short-circuit or a reverse polarity in the high-voltage mesh 110. The third switch 144 protects against internal errors, for example at a

Durchlegieren the lower half-bridge switch 152. The fourth switch 146 protects at an external reverse polarity in the low-voltage mesh 1 12 and thus on the low-voltage side.

The embodiment shown in Figure 3 is technically easy to implement. Furthermore, with this a reduction of the quiescent current is possible.

FIG. 4 shows yet another embodiment of the circuit arrangement 200 with a DC-DC converter 202 between a high-voltage mesh 204 and a low-voltage mesh 206. In this case, only one switch 210 is provided in the DC-DC converter in the high-voltage mesh 204. The second switch can be omitted if there is no need to react to a polarity reversal of the high-voltage mesh, because this can be excluded, for example, by external measures.

Also in the DC-DC converter 202 on the low voltage side, d. H. in the low voltage mesh 206, a second switch 212 and a third switch 214 (B2B) are provided. However, these are not provided in the ground connection but in the potential connection of the low-voltage mesh.

The high voltage mesh 204 includes i.a. a switch 220 in series with a source 222. Parallel to these, an electric machine 224 is provided. Low-voltage mesh 206 further includes a source 230, a first consumer 232, a second consumer 234, and an additional consumer

236 provided.

The embodiment shown in Figure 4 is also technically easy to implement. Likewise, with this a reduction of the quiescent current is possible.

In Figure 5 tripping conditions are shown. The illustration shows a comparator 250, in this case a hardware comparator, a microcontroller 252 and a watchdog 254, in this case a hardware watchdog. Furthermore, the illustration shows a logic gate 256, in this case an OR gate.

In this version, the switches should have the following triggering conditions: The comparator 250 detects too high an output current.

The microcontroller 252 detects a malfunction.

The watchdog 254 detects a malfunction of the microcontroller 252.

The hardware comparator 250 compares an output, such as the output current or the output voltage, with a maximum threshold. The microcontroller 252 has a monitoring function for the output current. While this monitor function is more accurate than the hardware comparator 250, it is slower.

The hardware watchdog 254 ensures that the microcontroller 252 is operating correctly, i. H. that the microcontroller monitoring function, which should open the associated switch as needed, is executed properly.

If one of the three conditions is met, the associated circuit breakers should be opened immediately.

The microcontroller 250 can basically monitor operating conditions.

Claims

claims

1 . Protective circuit arrangement for a multi-voltage network (10) with a

A DC-DC converter (16, 52, 102, 202) provided in the region of a junction between a high-voltage mesh (12, 54, 110, 204) and a low-voltage mesh (14, 56, 112, 206), both in the high-voltage mesh (12, 54, 1 10, 204) as well as in the low-voltage mesh (14, 56, 1 12, 206) in each case at least one switch (90, 92, 120, 140, 142, 144, 146, 210, 212, 214) is provided.

2. Protective circuit arrangement according to claim 1, wherein the at least one switch of the high-voltage mesh is provided in the DC-DC converter.

The protection circuitry of claim 1 or 2, wherein the at least one switch (90, 92, 120, 140, 142, 144, 146, 210, 212, 214) of the low voltage mesh (14, 56, 112, 206) in the DC-DC converter (16, 52, 102, 202) is provided.

4. Protection circuit arrangement according to one of claims 1 to 3, wherein additionally in the high-voltage mesh (12, 54, 1 10, 204), a further switch (90, 92, 120, 140, 142, 144, 146, 210, 212, 214 ) is provided, which protects against reverse polarity in the high-voltage mesh (12, 54, 1 10, 204).

5. Protection circuit arrangement according to one of claims 1 to 4, in which in addition in the low-voltage mesh (14, 56, 1 12, 206), a further switch is provided which against reverse polarity in the low-voltage mesh (14, 56, 1 12, 206) protects.

A protection circuit arrangement according to any one of claims 1 to 5, wherein the switches (90, 92, 120, 140, 142, 144, 146, 210, 212, 214) are adapted to be opened in the presence of at least one tripping condition.

A protection circuit arrangement according to claim 6, wherein the first triggering condition is to be checked by comparing an output value with a limit value by means of a comparator (250).

8. Protection circuit arrangement according to claim 6 or 7, in which a second triggering condition by a monitoring function in a microcontroller (61, 252) is to be checked.

9. Protection circuit arrangement according to claim 8, wherein a third trigger condition by a watchdog (254), which ensures the correct operation of the monitoring function of the microcontroller (61, 252), is to be checked.

10. Protective circuit arrangement according to one of claims 1 to 9, wherein the switches (90, 92, 120, 140, 142, 144, 146, 210, 212, 214) are each realized by at least one MOSFET transistors.