Disconnecting switch

Abstract

An open circuit switch is provided for implementing bidirectional clamping. The open circuit switch has a first current path (56) and a second current path (58). A first group of open circuit switch elements and a second group of open circuit switch elements are arranged in the first current path (56), and a third group of open circuit switch elements and a fourth group of open circuit switch elements are arranged in the second current path (58), wherein each group of open circuit switch elements can be controlled.

Description

Technical Field

[0001] The invention relates to a disconnect switch (Trennschalter) with bidirectional clamping, which is particularly used in the vehicle electrical network of a motor vehicle. The invention also relates to a method for checking a disconnect switch, in particular a disconnect switch of the type described herein. Background Art

[0002] In automotive use, the vehicle electrical network should be understood as the totality of all electrical components in a motor vehicle. Thus, it includes both electrical appliances and power supply sources (such as generators) or electrical energy storage devices (such as batteries). In a motor vehicle, it should be noted that electrical energy is available in such a way that the motor vehicle can be started at any time and an adequate electrical supply is ensured during operation. However, even in the parked state, the electrical appliances should still be able to operate for an appropriate period of time without affecting subsequent starting.

[0003] In motor vehicles with electrically assisted or purely electric safety-related functions (such as steering or braking), there are high requirements for the availability of these functions during driving. Considering functional safety in accordance with ISO 26262, such functions can be classified according to the availability of ASIL C or D.

[0004] ASIL (Automotive Safety Integrity Level) is a key component of ISO 26262. The ASIL level is determined at the beginning of the development process. For this purpose, the system functions are analyzed and associated with possible risks. ASIL-A has the lowest risk level, and ASIL-D has the highest risk level.

[0005] According to the supply architecture of the vehicle electrical network, this requires electrical disconnect devices for decoupling from highly reliable partial supply networks (such as ASIL C or D, hereinafter referred to as Kl.30_1) and conventional partial supply networks (classified, for example, as QM, hereinafter referred to as Kl.30_0). QM is a classification lower than ASIL A and means that only conventional quality measures are carried out. In the case of a short circuit or overcurrent in the vehicle electrical network part Kl.30_0, this part of the vehicle electrical network is disconnected from the highly reliable vehicle power supply part Kl.30_1 by a disconnect switch, so that functions (such as a steering device or a brake) can be maintained without interference by the supply from Kl.30_1. Here, the safety objective of the disconnect switch is "safe disconnection".

[0006] The document DE 10 2008 043 402 A1 describes a method for protecting a device connected to a vehicle network against overvoltage, in which it is provided that the overvoltage is fed to a load that dissipates (abbauen) the overvoltage and consumes energy (energievernichtende). For example, the load that consumes energy can be configured as a starter.

[0007] A method for separating a vehicle network from a DC voltage converter is known from document DE 10 2014 201 581 A1. In this method, it is provided that the supply voltage is converted into a vehicle network voltage by means of a DC voltage converter, the blocking voltage at at least one of the semiconductor rectifier elements is determined, and the disconnect switch for decoupling the vehicle network from the DC voltage converter is controlled based on the value of the determined blocking voltage. Summary of the Invention

[0008] Against this background, a disconnect switch configured to enable bidirectional clamping and a method for checking the disconnect switch are proposed. Embodiments are derived from the extended technical solutions and the description.

[0009] The proposed disconnect switch with bidirectional clamping has a first current path and a second current path, wherein a first disconnect switch element group and a second disconnect switch element group are arranged in the first current path, and a third disconnect switch element group and a fourth disconnect switch element group are arranged in the second current path. Here, each of the disconnect switch element groups can be controlled separately or individually in the configuration. This means that each disconnect switch element group can be controlled independently of the other disconnect switch element groups. In principle, it is sufficient to provide for the common control of each path.

[0010] Importantly, the disconnect switch element groups (which typically have a series of disconnect switch elements, such as semiconductor switches like MOSFETs) are arranged such that the blocking of current flow can be achieved in both directions.

[0011] Therefore, a simplified structure of the disconnect switch with clamping elements (such as freewheeling diodes and Zener diodes) is proposed, which act in both current directions when turned off and thus only need to be provided once. In addition, it should be possible to perform a diagnosis of the blocking ability of the disconnect switch elements at the start of the driving cycle or even during operation.

[0012] Here, in the configuration, the disconnect switch is divided into two parallel current paths, which have groups of disconnect switch elements (for example, a group of MOSFETs), and these are always required to conduct all the current. By swapping the MOSFET arrangements in the two groups, the following possibilities result: on the one hand, a common overvoltage clamp is provided for both current directions, and on the other hand, a common freewheeling path is provided.

[0013] In addition, it is also possible to briefly switch off the MOSFET groups separately during operation in order to check the components.

[0014] The proposed method for checking the disconnect switch can in particular be carried out by means of a disconnect switch of the type described herein. This method can also be referred to as a method for performing diagnostics in a disconnect switch in which a first group of disconnect switch elements and a second group of disconnect switch elements are provided in at least one current path. Here, a resistor is connected between the two groups of disconnect switch elements and then the potential between the two groups of disconnect switch elements is monitored. Alternatively, a current source or a current sink can also be used. If the potential cannot be increased in the case of a pull-up resistor, or if the potential cannot be decreased by means of a resistor in the case of a pull-down resistor, then at least one of the disconnect switch elements is faulty.

[0015] Other advantages and configurations of the invention result from the description and the corresponding drawings.

[0016] It is understood that, without departing from the scope of the invention, the features mentioned above and those to be explained below can be used not only in the respectively described combinations, but also in other combinations or alone. Description of the Drawings

[0017] Figure 1 Shows an embodiment of the disconnect switch;

[0018] Figure 2 Shows an embodiment of the proposed disconnect switch;

[0019] Figure 3 Shows Figure 3 the disconnect switch in

[0020] Figure 4 and a diagram of the current flow; Detailed Description

[0021] The invention is schematically illustrated based on the embodiments in the drawings and is described in detail below with reference to the drawings.

[0022] Figure 1Shows an embodiment of a disconnect switch, which is generally labeled with reference numeral 10 and is based on disconnect switches hitherto used to protect highly reliable sub-vehicle networks. The figure shows a disconnect switch 10, which is arranged between a conventional vehicle network (represented here by terminal Kl.30_0 12 and having a QM classification) and a safety-related vehicle network (represented here by terminal Kl.30_1 14 and including an energy source, such as a battery). Safety-related electrical appliances (such as a steering device or a brake) are connected to Kl.30_1 14.

[0023] The figure has a first transistor group T1 20 and a second transistor group T2 22 as a group of disconnect switch elements, and these transistor groups are arranged in a back-to-back arrangement with respect to each other. The figure also shows the body diodes of the transistors of the two transistor groups 20 and 22, respectively. To control the first transistor group T1 20, a first gate driver 24 is provided, and to control the second transistor group 22, a second gate driver 26 is provided. In addition, for voltage limitation, a first Zener diode D1 28 is provided in parallel with the first transistor group T1 20, and a second Zener diode 30 is provided in parallel with the second transistor group T2 22.

[0024] The disconnect switch 10 can block in both directions. If there is a short circuit at terminal Kl.30_0 12, the current flow can be suppressed by means of the first transistor group T1 20. The current flow in the opposite direction can be suppressed by means of the second transistor group T2 22 in order to protect the body diode in the first transistor group T1 20 from an uncontrolled current flow.

[0025] It should be noted that the overvoltage clamping by means of the Zener diodes D1 / D2 28 / 30 is not referenced to ground (massebezogen), and thus an undesired overvoltage may occur depending on the supply voltage level.

[0026] The overvoltage that occurs when the MOSFET is turned off is limited by overvoltage clamping, and thus the MOSFET and the connected electrical appliances are protected from harmful voltages. By clamping or freewheeling (Freilauf), the negative voltage that occurs when the MOSFET is turned off is limited, and the MOSFET or the electrical appliance is protected.

[0027] The figure also shows a pull-up resistor 40, which enables the diagnosis or inspection of the transistors of groups 20 and 22, which are used as switches and are constructed, for example, as MOSFETs.

[0028] Components 42 and 44 are used for voltage measurement at the node. In principle, only one of the two components 42 and 44 is required for this purpose. Component 46 is used for current measurement, which can trigger the opening of the switch in the case of overcurrent, for example.

[0029] However, it is not possible to perform diagnostics by turning off the transistor or MOSFET during operation and measuring the opening ability, because the main current path is interrupted here.

[0030] Figure 2 An embodiment of the proposed disconnect switch is shown, which is labeled as a whole with reference numeral 50. This figure shows terminal Kl.30_0 52 and terminal Kl.30_1 54, between which the disconnect switch 50 is arranged. The disconnect switch 50 is further divided into two parallel current paths 56 and 58. In the first current path 56, a first transistor group T1 60 and a second transistor group T2 62 are provided as a group of disconnect switch elements. Correspondingly, in the second current path 58, a third transistor group T3 64 and a fourth transistor group T4 66 are provided as a group of disconnect switch elements. The first transistor group T1 60 and the second transistor group T2 62 are arranged in a face-to-face manner with respect to each other. The third transistor group T3 64 and the fourth transistor group T4 66 are arranged in a back-to-back manner with respect to each other.

[0031] A Zener diode D1 70 for preventing overvoltage 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 for limiting 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 inspection of the disconnect switch elements in T1 60 and T2 62 and the inspection of the function of the Zener diode D1 70. The pull-down resistor 76 enables the inspection of the disconnect switch elements in T3 64 and T4 66 and the inspection of the function of the freewheeling diode 74.

[0032] The clamping in the shown disconnect switch 50 can be carried out with respect to ground and used independently of the current supply voltage. Here, the terminal voltage is independent of the potential level of Kl.30_0 / _1 52 / 54.

[0033] If the disconnect switch 50 is opened and the energy stored in the lead inductance For the energy in [context], the clamping elements D1 70 and D2 74 function in both current directions. The Zener diode D1 70 limits overvoltage in the case of current flow in the break switch 50 through the body diodes of T1 60 or T2 62. Instead of the Zener diode D1 70, the clamping device can generally be implemented as a clamping circuit for positive overvoltage. The freewheeling diode D2 74 provides a freewheeling path for the current from the break 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 diode function.

[0034] By dividing the current path through T1 / T2 (60 / 62) and T3 / T4 (64 / 66) into two current paths 56, 58, the possibility of in-operation diagnosis is created. For this purpose, part of the path is switched off for diagnosis, while the other path takes on the full current for a short time.

[0035] The figure also shows the network ProtGND 80, which represents the ground for polarity reversal protection in the case where there is a possibility of polarity reversal with the occurrence of negative voltage in at least one of the two vehicle networks.

[0036] Component 90 is used to measure the drain-source voltage drop of the MOSFET. Component 92 is used for current measurement through the shunt.

[0037] Figure 3 shows Figure 2 the break switch 50 in [context], where an example of current flow during the turn-off due to the lead inductance during the clamping process of a large current from Kl.30_1 to Kl.30_0 can be identified.

[0038] The diagnostic scheme is as follows:

[0039] The diagnosis of the path T1 / T2 60 / 62 or T3 / T4 64 / 66 and the terminal structure can only be carried out in the off state of the path.

[0040] T1 / T2 60 / 62 checks the blocking ability by applying a positive voltage to V on the pull-up resistor 72. Here, V should be significantly higher than Kl.30_0 52 and Kl.30_1 54. The diagnostic voltage is limited upwards by the Zener voltage of D1 70. Thus, the blocking ability of the MOSFET can be checked and at the same time the functional ability of D1 70 can be checked.

[0041] Similarly, T3 64 and T4 66 can check the blocking ability by applying a negative voltage to V on the pull-down resistor 76. Limiting the diagnostic voltage to about 0.7V to 1.0V below ProtGND 80 by D2 74 also indicates the conductivity of D2 74.

[0042] Diagnosis of the conductivity of the MOSFET is not necessary for the safety goal of "safe open circuit", but can be carried out by checking the credibility of the drain-source voltage drop when the current is known. Here, the drain-source voltage drop is increased by interrupting the faulty MOSFET. For this function, components 90 and 92 are required.

[0043] Clamping components D1 70 and D2 74 are drawn representatively, and multiple series components or switches may be included in the application. This is especially possible due to ASIL classification and the necessity of avoiding simple faults and diagnostic requirements.

[0044] Figure 4 Another embodiment of the open switch 100 with two redundant open circuit components is shown. The figure shows terminals Kl.30_0 102 and Kl.30_1 104, between which the open switch 100 is arranged. The open switch 100 is further divided into two parallel current paths 106 and 108. In the first current path 106, a first transistor group T1 110 and a second transistor group T2 112 are provided as a group of open circuit switch elements. Correspondingly, in the second current path 108, a third transistor group T3 114 and a fourth transistor group T4 116 are provided as a group of open circuit switch elements.

[0045] Additionally, a fifth transistor group T5 120 is provided in the first current path 106, and a sixth transistor group T6 122 is provided in the second current path 108. The figure also shows a pull-up resistor 130, a Zener diode D1 132, a first resistor R1 134, a second resistor R2 136, a pull-down resistor 140, a freewheeling diode 142, a third resistor R3 144, and a fourth resistor R4 146.

[0046] According to the requirements of the characteristic numbers for the measurement of functional safety, an implementation of redundancy for the open circuit components may be required. In the topology, this is represented by additional MOSFETs T5 120 and T6 122. By inserting MOSFETs T5 120 and T6 122, now two MOSFET groups are redundantly available for turning off the current flow from Kl.30_1 to Kl.30_0, namely T1 110 / T5 120 and T4 116 / T6 122. Therefore, a short circuit in one of the MOSFET groups also results in the loss of the open circuit function that is safe for single faults.

[0047] The loss of the open circuit function that is safe for single faults.

[0048] In order to also be able to perform the diagnostics of all relevant MOSFETs here, a diagnostic network composed of R1 to R4 is additionally provided. If these resistors are implemented, for example, with the same value, then in the diagnostic state (i.e., the switches in the path are AUS), at the new measurement points between T1 / T5 and T4 / T6, half of the differential voltage of the voltages to be checked on T1 / T5 and T4 / T6 is obtained respectively. Thus, it is also possible to check the open-circuit capability of the additional redundant MOSFETs in the blocking direction. In principle, the diagnostic network can be provided by a voltage measuring device.

Claims

1. A circuit breaker, the circuit breaker being configured to enable bidirectional clamping, the circuit breaker having a first current path (56, 106) and a second current path (58, 108), wherein, A first set of open switch elements and a second set of open switch elements are arranged in the first current path (56, 106), and a third set of open switch elements and a fourth set of open switch elements are arranged in the second current path (58, 108), wherein each set of open switch elements can be controlled. Wherein, a Zener diode (70, 132) is connected between the two sets of open switch elements in the first current path (56, 106). Wherein, a freewheeling diode (74, 142) is connected between the two sets of open switch elements in the second current path (58, 108). Wherein, the first set of open switch elements (60) and the second set of open switch elements (62) are interconnected in a front-to-front arrangement, and the third set of open switch elements (64) and the fourth set of open switch elements (66) are interconnected in a back-to-back arrangement.

2. The open switch according to claim 1, wherein additional open switch elements are provided in the two current paths (56, 58, 106, 108) of the open switch.

3. The open switch according to claim 1 or 2, wherein a pull-up resistor (40, 72, 130) is connected between the two sets of open switch elements in the first current path (56, 106), and a pull-down resistor (76, 140) is connected between the two sets of open switch elements in the second current path (58, 108), and the pull-up resistor and the pull-down resistor are used to check the corresponding open switch elements.

4. The open switch according to claim 2, wherein a diagnostic network is additionally assigned to each current path (56, 58, 106, 108).

5. The open switch according to claim 1 or 2, wherein MOSFETs are provided as open switch elements, and the MOSFETs can be controlled by gate drivers (24, 26) respectively.

6. A method for checking a disconnector switch (10, 50, 100) according to any one of claims 1 to 5, wherein, Connect the pull-up resistor (40, 72, 130) between the two sets of open switch elements in the first current path (56, 106) of the open switch (10, 50, 100), and then monitor the potential between the two sets of open switch elements in the first current path (56, 106) of the open switch (10, 50, 100), and / or, wherein, connect the pull-down resistor (76, 140) between the two sets of open switch elements in the second current path (58, 108) of the open switch (10, 50, 100), and then monitor the potential between the two sets of open switch elements in the second current path (58, 108) of the open switch (10, 50, 100).

7. The method according to claim 6, wherein the method is executed during the operation of the open switch (10, 50, 100).

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