WO2020216486A1

WO2020216486A1 - Disconnector switch

Info

Publication number: WO2020216486A1
Application number: PCT/EP2020/053250
Authority: WO
Inventors: Roman Gronbach
Original assignee: Robert Bosch Gmbh
Priority date: 2019-04-23
Filing date: 2020-02-10
Publication date: 2020-10-29
Also published as: DE102019205801A1; CN113711453A

Abstract

The invention relates to a disconnector switch which is designed to enable bidiretional clamping, comprising a first current path (56) and a second current path (58), a first disconnector switch element group and a second disconnector switch element group being arranged in the first current path (56), and a third disconnector switch element group and a fourth disconnector switch element group being arranged in the second current path (58) Each disconnector switch element group is to be activated.

Description

description

title

Disconnector

The invention relates to a circuit breaker with bidirectional clamping, which is used in particular in an on-board network of a motor vehicle. The invention further relates to a method for checking a circuit breaker, in particular a circuit breaker of the type described herein.

State of the art

In automotive use, an on-board network is understood to mean the entirety of all electrical components in a motor vehicle. Thus, both electrical consumers and supply sources, such as. Generators or electrical storage, z. B. Batteries includes. In the motor vehicle it must be ensured that electrical energy is available in such a way that the

Motor vehicle can be started at any time and a sufficient power supply is ensured during operation. However, even when switched off, electrical consumers should still be operable for a reasonable period of time without a subsequent start being impaired.

In motor vehicles with electrically assisted or purely electrically executed, safety-relevant functions, such as, for example, the steering or brakes, there are high demands on the availability of these functions while driving. Taking into account the functional safety according to ISO 26262, such functions can be classified with an availability according to classification ASIL C or D.

ASIL (Automotive Safety Integrity Level) is a key component of ISO 26262. The ASIL level is set at the beginning of a development process certainly. For this purpose, the system functions are analyzed and related to possible risks. ASIL-A has the lowest risk level, ASIL-D the highest risk level.

Depending on the supply architecture of the on-board network, this requires an electrical isolating device to decouple highly reliable sub-supply networks, e.g. ASIL C or D, here called Kl. 30_1, and conventional sub-supply networks, classification z. B. QM, here called class 30_0. QM is a classification below ASIL A and means that only conventional quality measures are carried out. In the event of short circuits or overcurrents in the on-board power supply terminal 30_0, it is disconnected from the highly reliable on-board power supply terminal 30_1 via a disconnector in order to maintain functions such as the steering or the brake with a supply from terminal 30_1. The safety goal for the disconnector here is "safe disconnection".

The document DE 10 2008 043 402 A1 describes a method for protecting devices connected to an on-board network from an overvoltage, in which it is provided that the overvoltage is fed to an energy-destroying load which reduces the overvoltage. The energy-destroying load can, for example, be designed as a starter.

From the publication DE 10 2014 201 581 A1 a method for separating an on-board network from a DC voltage converter is known. The method provides a supply voltage with a

To convert DC voltage converter into an on-board network voltage, to determine a reverse voltage on at least one of the semiconductor rectifier elements and to control an isolating switch for decoupling the on-board network from the DC voltage converter as a function of the value of the determined reverse voltage.

Disclosure of the invention Against this background, a circuit breaker according to claim 1 and a method with the features of claim 8 are presented. Embodiments emerge from the dependent claims and the description.

The presented circuit breaker with bidirectional clamping has a first current path and a second current path, a first circuit breaker element group and a second in the first current path

Disconnector element group are arranged and in the second current path a third disconnector element group and a fourth

Disconnector element group are arranged. Everyone is the

Disconnector element groups to be controlled separately or separately in configuration. This means that each disconnector element group can be controlled independently of the other disconnector element groups. Basically, it is sufficient to provide a common control for each path.

It is important that the disconnector element groups, typically a series of disconnector elements, such as semiconductor switches, e.g. B. MOSFETs have, are arranged to each other that blocking a current flow is possible in both directions.

It thus becomes having a simplified structure of the circuit breaker

Clamping elements, such as, for example, freewheeling diodes and Zener diodes, are presented, which act in both directions of current when switched off and are therefore only required once. In addition, it should be possible to diagnose the disconnector elements for blocking capability at the beginning of a driving cycle or even during operation.

In one embodiment, the disconnector is divided into two parallel current paths with groups of disconnector elements, such as, for example, MOSFET groups, which are required in any case to conduct the total current. By interchanging the MOSFET arrangement in both groups, it is possible, on the one hand, to provide a common overvoltage clamp for both current directions and, on the other hand, to provide a common freewheeling path. Furthermore, one MOSFET group can also be switched off briefly during operation in order to check the elements.

The method presented for checking a circuit breaker can in particular be carried out with a circuit breaker of the type described herein. This method can also be referred to as a method for carrying out a diagnosis in a circuit breaker in which a first circuit breaker element group and a second circuit breaker element group are provided in at least one current path. A resistor is connected between the two disconnector element groups and the potential between the two disconnector element groups is then monitored. Alternatively, a current source or a current sink can also be used. If the potential cannot be increased with the resistor, in the case of a pull-up resistor, or decreased in the case of a pull-down resistor, then at least one of the circuit breaker elements is defective.

Further advantages and embodiments of the invention emerge from the description and the respective drawings.

It goes without saying that the features mentioned above and those yet to be explained below can be used not only in the respectively specified, but also in other combinations or alone, without departing from the scope of the present invention.

Brief description of the drawings

Figure 1 shows an embodiment of a circuit breaker.

Figure 2 shows an embodiment of the disconnector presented.

FIG. 3 shows the circuit breaker from FIG. 3 with an illustration of the current flows.

FIG. 4 shows a further embodiment of the disconnector presented. Embodiments of the invention.

The invention is based on embodiments in the drawings

shown schematically and is described below with reference to the

Drawings described in detail.

FIG. 1 shows an embodiment of a circuit breaker which is designated as a whole by the reference number 10 and which is based on a circuit breaker that has been used to date for the protection of highly reliable sub-board networks. The illustration shows the isolating switch 10, which is between a conventional electrical system, which is represented here by a terminal Kl. 30_0 12 and has a QM classification, and a safety-relevant electrical system, which is represented here by a terminal Kl. 30_1 14 and an energy source , such as. A battery, arranged. Safety-relevant consumers, such as a steering system or a brake, are connected to terminal 30_1 14.

The illustration has a first disconnector element group

Transistors group T1 20 and a second group of transistors T2 22, which are arranged in a back-to-back arrangement to one another. The illustration also shows the body diodes of the transistors of the two transistor groups 20 and 22. First gate drivers 24 are provided for driving the first transistor group T1 20 and second gate drivers 26 are provided for driving the second transistor group 22. Furthermore, a first Zener diode D1 28 and parallel to the second transistor group T2 22 a second Zener diode 30 are provided for voltage limitation in parallel with the first transistor group T1 20.

The circuit breaker 10 can block in both directions. If there is a short circuit at terminal Kl. 30_0 12, the current can flow using the first

Transistors group T1 20 are prevented. A current flow into the

The opposite direction can be prevented by means of the second group of transistors T2 22 in order to protect the body diodes in the first group of transistors T1 20 against uncontrolled current flow. It should be noted that the overvoltage clamping with the Zener diodes D1 / D2 28/30 is not referenced to ground and therefore unwanted overvoltages in

Can generate dependence of the supply voltage level.

An overvoltage clamp limits the overvoltage that occurs when the MOSFETs are switched off, thus protecting the MOSFETs and the connected loads from harmful voltages. When the MOSFETs are switched off, a negative voltage that occurs is limited by clamping or freewheeling and the MOSFETs or loads are protected.

The illustration also shows a pull-up resistor 40, which enables diagnosis or checking of the transistors in groups 20 and 22, which serve as switches and are, for example, designed as MOSFETs.

Components 42 and 44 are used to measure the voltage at the node, in principle only one of the two components 42, 44 being required for this. Component 46 is used to measure the current that z. B. can trigger disconnection of the switch in the event of overcurrent.

A diagnosis by switching off during operation by switching off the transistors or MOSFETs and measuring the separation capability is not possible, however, since the main current path is interrupted in this case.

FIG. 2 shows an embodiment of the circuit breaker presented, which is designated as a whole by the reference number 50. The illustration shows a terminal Kl.30_0 52 and a terminal Kl.30_1 54, between which the disconnector 50 is arranged. The circuit breaker 50 is in turn divided into two parallel current paths 56 and 58. In the first current path 56 are as

Isolating switch element groups a first transistor group T1 60 and a second transistor group T2 62 are provided. Correspondingly, a third transistor group T3 64 and a fourth transistor group T4 66 are provided as disconnector element groups in the second current path 58. The first transistor group T1 60 and the second transistor group T2 62 are provided in a front-to-front arrangement with respect to one another. The third transistor group T3 64 and the fourth Transistor groups T4 66 are provided in a back-to-back arrangement to one another.

A Zener diode D1 70 for protection against overvoltages and a pull-up resistor 72 are connected between the first transistor group T1 60 and the second transistor group T2 62. A freewheeling diode D2 74, which is used to limit the voltage, and a pull-down resistor 76 are connected between the third transistor group T3 64 and the fourth transistor group T4 66. The pull-up resistor 72 enables the

Isolating switch elements in T1 60 and T2 62 and a check of the function of the Zener diode D1 70. The pull-down resistor 76 enables the isolating switch elements in T3 64 and T4 66 to be checked and the function of the freewheeling diode 74 to be checked.

The disconnection switch 50 shown can be clamped with reference to ground and begins independently of the current supply voltage. The clamping voltage is not dependent on the level of the potentials at term. 30_0 / _1 52/54.

If the isolating switch 50 is opened and the energy stored in the supply line inductances is dissipated, the clamping elements D1 70 and D2 74 are effective in both current directions. The Zener diode D1 70 limits overvoltages in the event of a current flow in the disconnectors 50 through the body diode of T1 60 or T2 62. Instead of the Zener diode D1 70, the clamping can generally be implemented as a clamping circuit for positive overvoltages. The

Freewheeling diode D2 74 provides a freewheeling path for currents from the isolating switch 50 through the body diodes of T3 64 and T4 66 and can be implemented by means of a diode or a circuit with a diode function.

By dividing the current path into the two current paths 56, 58 through T1 / T2 (60/62) and T3 / T4 (64/66), the possibility of diagnosis arises in the

Business. For this purpose, a partial path is switched off for diagnosis, while the other path takes over the entire current for a short time. The illustration also shows a network ProtGND 80, which represents a ground protected against reverse polarity, if there is one in at least one of the two vehicle electrical systems

There is a possibility of polarity reversal with negative voltages occurring.

Component 90 is used to measure the drain-source voltage drop of the MOSFETs. Component 92 is used to measure the current through the shunt.

Figure 3 shows the circuit breaker 50 from Figure 2, an example of the

Current flow when a high current is switched off from Kl. 30_1 to Kl. 30_0 with clamping processes due to the lead inductances.

The diagnostic concept is as follows:

The diagnosis of a path T 1 / T2 60/62 or T3 / T4 64/66 as well as the

Clamping structures can only take place when the path is switched off.

T1 / T2 60/62 are checked for blocking capability by applying a positive voltage across the pull-up resistor 72 to V. V should be well above Kl. 30_0 52 and Kl. 30_1 54. The upper limit of the diagnostic voltage is the Zener voltage of D1 70. So that is

Blocking ability of the MOSFETs and at the same time the functionality of D1 70 can be checked.

Similarly, T3 64 and T4 66 can be checked for blocking capability by applying a negative voltage across the pull-down resistor 76 to V. Limiting the diagnostic voltage by D2 74 to approx. 0.7..1.0 V below ProtGND 80 also indicates the conductivity of D2 74.

A diagnosis of the conductivity of the MOSFETs is not required for a "safe disconnection" safety goal, but can be done by checking the plausibility of the drain-source voltage drop when the current is known. With an interruption

Failed MOSFETs increase the drain-source voltage drop. Elements 90 and 92 are required for this function. The clamping elements D1 70 and D2 74 are drawn representative and can contain several elements in series or switches in the application. This can be necessary in particular due to the ASIL classification and avoidance of single errors as well as diagnostic requirements.

FIG. 4 shows a further embodiment of the isolating switch 100 with two redundant isolating elements. The illustration shows a terminal Kl.30_0 102 and a terminal Kl.30_1 104, between which the disconnector 100 is arranged. The isolating switch 100 is in turn divided into two parallel current paths 106 and 108. In the first current path 106 are as

Isolating switch element groups a first transistor group T1 110 and a second transistor group T2 112 are provided. Correspondingly, a third transistor group T3 114 and a fourth transistor group T4 116 are provided as disconnector element groups in the second current path 108.

In addition, there is a fifth transistor group T5 120 in the first current path 106 and a sixth transistor group T6 122 in the second current path 108

intended. Furthermore, the illustration shows a pull-up resistor 130, a Zener diode D1 132, a first resistor R1 134, a second resistor R2 136, a pulldown resistor 140, a freewheeling diode 142, a third resistor R3 144 and a fourth resistor R4 146.

Depending on the requirements for the key figures of the metrics for the functional

Safety, a redundant design of the separating elements may be necessary. In the topology, this is expressed by the additional MOSFETs T5 120 and T6 122. By inserting the MOSFETs T5 120 and T6 122, two MOSFET groups are now available redundantly for switching off a current flow from terminal 30_1 to terminal 30_0, namely T1 110 / T5 120 and T4 116 / T6 122. A short circuit in one of the MOSFET groups does not lead to

Individual error resulting in the loss of the safety-relevant isolating function.

In order to be able to carry out the diagnosis of all relevant MOSFETs here too, the diagnosis network from R1..R4 has been added. Are these resistances z. B. executed with the same values, results in the diagnostic state, ie switch in path OFF, at the new measuring point between T1 / T5 and T4 / T6 each half Differential voltage of the test voltage across T1 / T5 and T4 / T6. This can also be used to check the ability of the additional redundant MOSFETs to isolate in the reverse direction. The diagnosis network can in principle be given by a voltage measuring device.

Claims

Expectations

1. Disconnector, which is set up to allow bidirectional clamping, with a first current path (56, 106) and a second

Current path (58, 108) wherein a first circuit breaker element group and a second circuit breaker element group are arranged in the first current path (56, 106) and a third group is arranged in the second current path (58, 108)

Circuit breaker element group and a fourth circuit breaker element group are arranged, each circuit breaker element group is to be controlled.

2. Circuit breaker according to claim 1, in which additional circuit breaker elements are provided in the two current paths (56, 58, 106, 108).

3. Disconnector according to claim 1 or 2, wherein in the first current path (56, 106) between the two disconnector element groups a pull-up resistor (40, 72, 130) and in the second current path (58, 108) between the two disconnector element groups Pull-down resistor (76, 140) is connected, which are used to check the respective circuit breaker elements.

4. Disconnector according to claim 2 and 3, in which each current path (56, 58, 106, 108) is additionally assigned a diagnostic network.

5. Disconnector according to one of claims 1 to 4, wherein in the first

A Zener diode (70, 132) is connected between the two disconnector element groups in the current path (56, 106).

6. Disconnector according to one of claims 1 to 5, in which in the second

In the current path (58, 108) a freewheeling diode (74, 142) is connected between the two disconnector element groups.

7. Disconnector according to one of claims 1 to 6, in which as

Isolating switch elements MOSFETs are provided which are each to be controlled via gate drivers (24, 26).

8. A method for checking a circuit breaker (10, 50, 100), in which in at least one current path (56, 58, 106, 108) a first

Circuit breaker element group and a second circuit breaker element group are provided with a resistor between the two

Isolating switch element groups is switched and then the potential between the two isolating switch element groups is monitored.

9. The method according to claim 8, which is carried out for diagnosing a circuit breaker (10, 50, 100) according to one of claims 1 to 7.

10. The method according to claim 8 or 9, during an operation of the

Disconnector (10, 50, 100) is carried out.