CN116805564A

CN116805564A - Switching device with MEMS relay

Info

Publication number: CN116805564A
Application number: CN202310293447.1A
Authority: CN
Inventors: F·莫洛克; T·巴赫; Y·Z·博杜尔
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2022-03-25
Filing date: 2023-03-23
Publication date: 2023-09-26
Also published as: DE102022202971A1

Abstract

The invention relates to a switching device (1), comprising: -a first MEMS relay (2) having two switch-on portions (3, 4) and at least one control-on portion (5), wherein an electrical connection between the switch-on portions (3, 4) can be switched by applying a control signal to the control-on portions, wherein the switch-on portions of the first MEMS relay (2) are arranged in a current path (12); -switching logic (6) coupled with the control switch-on portion (5) of the first MEMS relay (2) for switching the first MEMS relay (2) by means of the control signal.

Description

Switching device with MEMS relay

Technical Field

Battery-operated systems, in particular associated control units (e.g. battery management systems), have high demands on their quiescent current (Ruhestrom) in order to avoid discharging the associated battery during the idle state (Ruhezustand). In most of these systems, a transistor is used as a switching element. Such transistors are used here at different locations in the system. However, this often results in a lossy current continuing to flow through these transistors or requiring switching of the transistors, especially when the system is in an idle state.

Background

In particular, fuses (sicfurngen) and transistors, by means of which parts of the system are deactivated in the idle state, often lead to unnecessary losses.

As safety devices for protection against overcurrent, use is often also made of fuse safety devices whose time-and temperature-dependent properties are selected such that they interrupt the conduction of current if necessary. In this case, the fuse is designed in particular in such a way that it is robust and electrically conductive over the nominal current and temperature range. The current required to blow the fuse is significantly higher than allowed in the normal range. Typically, the trigger time is estimated for a current in the normal range of 2 to 10 timesUp to 10 seconds. This property is sufficient to cope with high over-currents, for example, occurring in case of short-circuits. However, this is a relatively inaccurate performance in terms of preventing faults that only result in a small increase in current. Such a fuse protector has other disadvantages. For example, they are sensitive to moisture, dust, salt and similar external influences that may cause leakage currents. The heating of the fuse prior to triggering can also lead to undesirable thermal effects.

With respect to shutting down the system during the idle state, transistors are typically used in order to deactivate unused hardware functions during the idle state. However, such a transistor also has disadvantages as a semiconductor, since it for example causes additional voltage drops, voltage losses and requires additional control electronics. A field effect transistor just means that a high overhead control electronics is required. This results in the need for more components on the circuit board on which it is based and additional electrical consumers through the transistors.

In battery management systems, it is common to shut down some functions to save power. This also applies to systems that typically require low operating currents, such as voltage dividers for voltage identification. This results in high demands on the current loop that is switched off, since the nominal current that should be switched off during the idle state is in the same range as the leakage current of the switching element used. This results in that MOSFETs (metal oxide field effect transistors) are often used for such functions, which however results in relatively high manufacturing costs. Even in the case of particularly large currents, correspondingly expensive FETs have to be installed, which also leads to unnecessary increases in costs.

Disclosure of Invention

The switching device according to the invention comprises a first MEMS relay having two switch-on sections and at least one control-on section, wherein an electrical connection between the switch-on sections is switched by applying a control signal to the control-on sections, and switching logic (Schaltlogik), wherein the switch-on sections of the first MEMS relay are arranged in the current path, said switching logic being coupled to the control-on sections of the first MEMS relay in order to switch the MEMS relay by means of the control signal.

MEMS relays are a type of "microelectromechanical relay". The MEMS relay has at least two switch-on portions. However, the MEMS relay may also have a plurality of switch-on portions that are switched in common. The electrical connection is switched by the switch-on portion. In particular, the MEMS switch of the MEMS relay is arranged between two switch-on parts in order to connect the two switch-on parts in a switchable manner. The MEMS relay also has a control switch. The electrical connection between the switch-on portions may be switched by applying a control voltage to the control-on portions. The control voltage is specified here in particular by a control signal. The control signal therefore has, in particular, an on state (EIN-z ustand) in which the two switch-on parts are electrically conductively coupled to one another; and an off state (AUS-z ustand) in which the connection between the switch-on portions is disconnected from each other. The switch-on portion of the first MEMS relay is arranged in the current path so as to switch it. This means that the current path is routed through the switch-on section and can be switched by the MEMS relay.

The switching logic is a control circuit by which a control signal is provided to switch the first MEMS relay. For this purpose, the switching logic is coupled to the control switch-on of the first MEMS relay.

By combining the first MEMS relay with switching logic, a particularly highly integrated and cost-effective safety device can be achieved, which can be used for different products and applications, in particular in the field of battery management systems. The switching logic is in particular an ASIC (application specific integrated circuit).

Alternative embodiments show preferred embodiments of the invention.

The switching device preferably comprises a temperature sensor, a current sensor and/or a voltage sensor, which are logically coupled to the switch, wherein the switching device is in particular designed as a safety device, preferably as an overload safety device or an overcurrent safety device. The temperature sensor is provided in particular for detecting the temperature of the MEMS relay. The current sensor is particularly suitable for detecting a current flowing through a current path. The voltage sensor is provided in particular for detecting a voltage drop between one of the switch-on parts and circuit ground or between two switch-on parts. Each of the above-mentioned sensors is adapted to detect the state of the MEMS relay, which is derived in particular from the current flowing through the current path. For example, the large current flowing through the current path may be detected either indirectly by heating the MEMS relay or directly by a current sensor. The overvoltage may also be detected by a voltage sensor. If an especially high current, an especially high voltage or an especially high temperature is detected by one of the sensors, this can be used for triggering the switching process. In this case, the electrical connection between the two switch-on parts of the MEMS relay is broken, in particular if the current temperature, the current flowing or the current voltage exceeds a threshold value. The switching is performed by means of switching logic. A circuit can thus be provided in the current path that acts in correspondence with the safety device. Such a safety device is preferably designed as an overload safety device or an overcurrent safety device. The entire switching device is preferably arranged in an industry-standard safety housing.

The switching device preferably comprises a temperature sensor which is logically coupled to the switch and is arranged such that the temperature of the first MEMS relay is detected. The switching device further comprises a current sensor logically coupled to the switch and arranged for detecting a current flowing through the current path. The switching logic is provided for determining the aging state and/or overload of the MEMS relay based on the detected temperature and the detected current. In particular, the temperature of the MEMS relay is determined when the associated current flows through the current path. Depending on the internal resistance of the MEMS relay, the first MEMS relay will heat up differently depending on its aging state and a higher temperature is measured with the aging increasing with the present specific current. This distribution between the flowing current and the associated detected temperature is evaluated by the switching logic and the aging state of the MEMS relay is deduced therefrom. Alternatively or additionally, an overload of the MEMS relay can be ascertained, wherein, in particular, high currents lead to high temperatures.

It is also advantageous if the switching device comprises a voltage sensor which is arranged to detect a voltage drop between the switch-on parts. In this case, the switching logic is preferably provided for determining, based on the detected voltage drop and the control signal, whether the first MEMS relay is in a switching state corresponding to the control signal. When the first MEMS relay is actuated by the output control signal, it is evaluated by the switching logic, in particular, whether the first MEMS relay is in a connected (durchgeschaltet) state. When the MEMS relays are connected, the voltage drop between the two switch-on portions of the first MEMS relay is particularly low. Accordingly, when the MEMS relay is turned off according to the control signal, a voltage drop between the switch-on portions of the MEMS relay is relatively high. However, if the first MEMS relay has a fault, for example, a mechanical switch inside the MEMS relay may be faulty. In this case, the first MEMS relay has a high voltage drop across its switch-on portion in a state of communication according to the control signal. In other cases, the MEMS relay has a low voltage drop between its switch-on portions in a state of being turned off according to the control signal. This can be identified by the switching logic.

It is also advantageous if the switching device comprises a voltage sensor, wherein the voltage sensor is provided for detecting a voltage drop between the switch-on parts of the first MEMS relay and for detecting a second voltage drop between the switch-on parts of the second MEMS relay, wherein the switching logic is provided for determining which of the MEMS relays is in a switching state corresponding to the control signal based on the detected first voltage drop, the detected second voltage drop and the control signal. The switching device comprises in particular two MEMS relays connected in series, which are formed by a first MEMS relay and a second MEMS relay. The two MEMS relays are preferably switched in a corresponding manner by two control signals. Alternatively, the second MEMS relay is connected in parallel with the first MEMS relay. In this case, the safety during the switching off process can be increased by the series-connected MEMS relays, since in the event of a functional failure of one MEMS relay the current path is also broken. In this case, the switching-on process can be ensured in particular by the MEMS relays connected in parallel, since the current path can be switched on even in the event of a functional failure of one of the MEMS relays. By detecting which of the MEMS relays has a fault (which may be identified by one of the MEMS relays not being in a switching state corresponding to the control signal), it may be analyzed whether the process switching device may continue to operate. For example, if two MEMS relays are connected in parallel and one of the MEMS relays cannot be switched to the off state, the switching device can continue to operate, since the switching process can also be performed by the remaining MEMS relays. Preferably, an error signal is output by the switching logic, for example to request service to the switching device upon recognizing that the first MEMS relay is not in a state corresponding to the control signal.

Preferably, the switching device comprises a current sensor coupled to the switching logic, wherein the current sensor is arranged to detect a current flowing through the current path, wherein the switching logic is arranged to break an electrical connection between the switch-on portions of the first MEMS relay in response to the detected current exceeding a predetermined threshold. Thus realizing a safety device for current switching.

The switching device further preferably comprises a temperature sensor coupled to the switching logic, wherein the temperature sensor is provided for detecting a temperature of the first MEMS relay, wherein the switching logic is provided for switching off an electrical connection between the switch-on parts of the first MEMS relay in response to the detected temperature exceeding a predefined threshold value. A temperature-controlled safety device can thus be realized. Depending on the arrangement of the temperature sensor, the temperature increase may result from excessive current flowing through it or from the ambient temperature of the first MEMS relay.

It is also advantageous that the switching logic comprises a communication interface enabling to invoke information about the state of the switching device and/or to manipulate the switching logic to switch the first MEMS relay to a desired switching state. A flexible switching device is thus achieved which is capable of providing a feedback signal to the upper circuit (u berlegende Schaltung). A reliable switching process can thus be provided by the switching device. The information about the state of the switching device preferably comprises a measured value of a sensor of the switching device, a state of the switching device determined on the basis of one of the sensors, or an indication about the switching state of the MEMS relay. The switching logic can be operated in particular to switch the first MEMS relay to a connected switching state after it has been switched to a non-conductive state due to overload or overvoltage.

It is furthermore advantageous if the switching device comprises a second MEMS relay, the switch connections of which are arranged in series with the switch connections of the first MEMS relay in the current path, and the control connections of which are also logically coupled to the switches, wherein the second MEMS relay is switched by the switch logic corresponding to the first MEMS relay. Optionally, the first MEMS relay is switched separately from the second MEMS relay. Accordingly, it is preferable to provide separately generated control signals for the first MEMS relay and the second MEMS relay at the control turn-on portion to increase redundancy. A redundancy-protected shut-down procedure can be provided by MEMS relays arranged in series.

A battery management system comprising a switching device according to the invention is also advantageous. The switching device based on the first MEMS relay is particularly advantageous here, since this results in a low leakage current and a low current required for actuating the switching process. Thus ensuring a particularly low power consumption of the battery management system.

The battery management system preferably includes: a first control electronics component by which operation of the battery management system is controlled in an energy saving mode, the first control electronics component being supplied with an operating voltage by at least one battery cell, wherein the first control electronics component comprises switching logic; and a second control electronics which is supplied with an operating voltage by the at least one battery cell via a current path switchable by means of the first MEMS relay, wherein the first control electronics are provided for switching the first MEMS relay in the energy saving mode to disconnect the second control electronics from the operating voltage. The component of the battery management system, here the second control electronics, is therefore switched off in the idle state by the first MEMS relay of the switching device. The first MEMS relay is preferably in an off state when the control signal is in a low mode, i.e. having a lower voltage than when the first MEMS relay is in communication via the control signal. Thus, there is no need to provide a voltage that maintains the desired switching state during the idle state. Thus, a particularly efficient first control electronics can be realized and leakage currents through the first MEMS relay are blocked. This therefore enables a particularly efficient battery management system with particularly low consumption in the idle state.

It is also advantageous if the second control electronics are coupled to different battery cells via a plurality of current paths, wherein each of the current paths comprises a MEMS relay that can be controlled by the first control electronics in order to disconnect the second control electronics from one or more of the battery cells. In particular, the state of the individual battery cells is detected by the second control electronics, wherein this takes place via a plurality of current paths. This is not absolutely necessary in the idle state. If the plurality of current paths are each disconnected from the second control electronics via the associated MEMS relay, this prevents a current supplied by the battery cell from flowing, for example, through the measuring resistor and thus causing losses.

The battery pack for an electric bicycle comprising the battery management system according to the invention is also advantageous, wherein the battery pack has a housing, wherein a plurality of battery cells, in particular cylindrical round battery cells, are arranged in the housing. The battery cell is preferably a battery cell or comprises a plurality of battery cells.

Drawings

Exemplary embodiments of the present invention are described in detail below with reference to the accompanying drawings. The drawings show:

FIG. 1 shows a schematic diagram of a MEMS relay with an associated equivalent circuit;

fig. 2 shows a schematic diagram of a switching device according to a first embodiment of the invention;

fig. 3 shows a schematic view of a switching device according to a second embodiment of the invention;

fig. 4 shows a schematic view of a switching device according to a third embodiment of the invention;

fig. 5 shows a schematic diagram of a switching device according to a fourth embodiment of the invention;

fig. 6 shows a schematic diagram of a switching device according to a fifth embodiment of the invention;

fig. 7 shows a schematic view of a switching device according to a sixth embodiment of the invention;

fig. 8 shows a schematic diagram of a switching device according to a seventh embodiment of the invention;

fig. 9 shows a schematic view of a battery management system according to an eighth embodiment of the present invention;

fig. 10 shows a schematic view of a battery management system according to a ninth embodiment of the present invention;

fig. 11 shows a schematic diagram of a battery management system according to a tenth embodiment of the present invention.

Detailed Description

Fig. 1 shows a schematic diagram of a MEMS relay 2, which is typically arranged in a switching device 1 according to the invention. An associated equivalent circuit diagram of the MEMS relay 2 is also shown. The MEMS relay 2 has a first switch-on portion 3 and a second switch-on portion 4. The MEMS relay 2 further includes a control switch 5. The two switch-on portions 3,4 and the control-on portion 5 are arranged on a substrate 15. The micromechanical conductor 16 is arranged on the second switch-on part 4 and extends beyond the control switch-on part 5 to the first switch-on part 3. In the idle state, the micromechanical conductor 16 is not in contact with the first switch-on 3. However, if a control signal is applied to the control switch-on portion 5, an electromagnetic field is generated and the electrical conductor 16 is pulled towards the first switch-on portion 3, so that an electrically conductive connection between the first switch-on portion 3 and the second switch-on portion 4 is produced.

Here, if a switching voltage with a control signal is applied to the control on portion 5, the MEMS relay 2 may be brought into an on state or a communication state. Further, when there is no control signal or the control signal has a low voltage level at the control on portion 5, the MEMS relay may be switched to an off state or a non-on state.

It can be seen from the equivalent circuit diagram that a controllable switch is thus realized. The switching device 1 has at least one first MEMS relay 2 having a corresponding structure.

Fig. 2 shows a switching device according to a first embodiment of the present invention. The first MEMS relay 2 is arranged in the current path 12. The current path 12 here extends through the switch-on parts 3,4 of the first MEMS relay 2 and is thus switchably implemented. The switching device 1 further comprises a switching logic 6, which switching logic 6 is coupled to the control switch-on 5 of the first MEMS relay 2 in order to switch the first MEMS relay 2 by means of a control signal. Here, a high voltage level is applied to the control switch-on portion 5 by means of a control signal by the switching logic 6 to switch the MEMS relay 2 to the conductive state, and a low voltage level is applied to the control switch-on portion 5 to switch the MEMS relay 2 to the non-conductive state. Both are implemented by means of control signals which may take either a high voltage level or a low voltage level. It should be noted that in alternative embodiments of the MEMS relay, it is also possible to switch to the off-state by a high voltage level and to switch to the on-state by a low voltage level.

The switching device 1 further comprises a current sensor 8 coupled to the switching logic 6. The current sensor 8 is provided for detecting a current flowing through the current path 12. For this purpose, the current sensor 8 comprises in particular an inductive measuring circuit arranged around the current path 12 or a measuring resistor integrated into the current path 12. The current flowing through the current path 12 is measured by the current sensor 8 and transmitted as a measured value to the switching logic 6. The switching logic is provided for switching off the electrical connection between the switching-on parts 3,4 of the first MEMS relay 2 in response to the detected current exceeding a predefined threshold value. The threshold value is predefined for the switching logic 6, wherein the threshold value is designed as a fixed value or can be configured via the communication interface.

If the current flowing through the current path 12 rises above the threshold value, the first MEMS relay 2 is switched to a non-conductive state by the control signal and thus the current flowing through the current path 12 is interrupted. The switching logic 6 is preferably designed such that after a reset, the first MEMS relay 2 is again placed in the conductive state, for example by switching off all voltages. Instead of this, the first MEMS relay 2 is always put in the open state, which is achieved, for example, by: the switching logic 6 comprises a non-volatile memory. Hereby it is achieved that the first MEMS relay 2 cannot be switched back to the conducting state by simply disconnecting the switching device 1 from all voltages. The switching logic 6 optionally has a communication interface and can be reset via this interface in order to switch the first MEMS relay 2 back into the conducting state.

Fig. 3 shows a schematic diagram of a switching device 1 according to a second embodiment of the invention. The second embodiment of the present invention substantially corresponds to the first embodiment of the present invention. In addition to the current sensor 8, the switching device 1 here also comprises a temperature sensor 7. A temperature sensor 7 is arranged at the first MEMS relay 2 and is coupled with the switching logic 6. The temperature of the MEMS relay 2 is detected by a temperature sensor 7 and provided as a measured value to the switching logic 6. The switching logic 6 is provided for determining the aging state and/or overload of the MEMS relay 2 on the basis of the detected temperature and the detected current through the current path 12. In this way, an overload is determined, in particular, when the temperature or the temperature associated with a specific current exceeds a predefined threshold value. The threshold value may be determined for a specific measuring current or it may be a generic threshold value which is adapted independently of the measuring current. In particular when there is an overload of the MEMS relay 2, a control signal is output to switch the first MEMS relay 2 to a non-conductive state. The aging state of the MEMS relay 2 is also determined from the combination of the detected temperature and the detected current. The internal resistance of the MEMS relay 2 generally increases as the MEMS relay 2 ages. The increased internal resistance results in the MEMS relay 2 heating more strongly as current flows through the current path 12. In particular, it can be determined to what extent the MEMS relay 2 heats up when a certain current flows. The extent of heating can be assigned to aging conditions. Thus, for example, the following can be defined: if the current path does not have aging, the first MEMS relay 2 heats up by 1 c when a current of 1mA flows through the current path 12. If it is detected by the switching logic 6 that the temperature of the first MEMS relay 2 rises by 2 ℃ when a current of 1mA flows, it is inferred from this that the first MEMS relay 2 enters aging. The values mentioned above are chosen for illustration purposes. It can be seen that by appropriately selecting different thresholds for the temperature and the associated current, different aging states can be identified. The time-dependent change in the internal resistance of the MEMS relay 2, which is defined in particular by the contact resistance between the micromechanical components, is thus measured. The increase in internal resistance may lead to a larger current loss in the case of a high load current through the MEMS relay 2, which may lead to a temperature increase. If a strong temperature increase, in particular a predefined temperature increase, is detected, the MEMS relay 2 is switched to the non-conductive state by the switching logic 6. The switching device 1 is preferably kept in this state, which is achieved for example by means of state storage in a non-volatile memory.

The switching logic 6 is thus also provided for switching off the electrical connection between the switching-on parts 3,4 of the first MEMS relay 2 in response to the detected temperature exceeding a predefined threshold value. The detected temperature can be fixedly predefined or dependent on the flowing current. In a further embodiment, the switching device 1 comprises only the temperature sensor 7 and not the current sensor 8.

Fig. 4 shows a schematic diagram of a switching device 1 according to a third embodiment of the present invention. The third embodiment of the present invention substantially corresponds to the first and second embodiments of the present invention. The switching device 1 here additionally comprises a voltage sensor 9. The voltage sensor 9 is arranged to detect a voltage drop between the switch-on parts 3, 4. The first switching element of the voltage sensor is coupled in particular to the first switching element 3, and the second measuring element of the voltage sensor 9 is coupled to the second switching element 4.

The voltage drop across the switch-on sections 3,4 is detected by a voltage sensor 9 and supplied as a measured value to the switching logic 6. The switching logic 6 is provided for determining whether the first MEMS relay 2 is in a switching state corresponding to the control signal based on the detected voltage drop and the control signal present. This means that when the MEMS relay 2 is manipulated by the control signal to be in the on state, it is determined by the switching logic 6 whether the MEMS relay 2 is actually in the on state. Accordingly, when the first MEMS relay 2 is requested to switch to the non-conductive state by the control signal, it is determined by the switching logic 6 whether the first MEMS relay 2 is in the non-conductive state. Therefore, the deviation between the desired switching state of the MEMS relay 2 and the switching state of the MEMS relay 2 requested by the switching logic 6 is determined. This is achieved on the basis of the voltage drop determined by the voltage sensor 9. When the MEMS relay 2 is switched to the conducting state, the voltage drop over the switch-on parts 3,4 is typically very low, preferably equal to zero. This is because the internal resistance through the MEMS relay 2 only results in a very small voltage drop. If the MEMS relay 2 is in a non-conductive state, the internal resistance of the MEMS relay 2 becomes very high and the voltage drop between the switch-on parts 3,4 of the first MEMS relay 2 increases accordingly. Thus, the voltage drop detected by the voltage sensor 9 can be used as a direct indication of: which switching state the MEMS relay 2 is in. Thus, by means of the switching logic 6 it is possible to adjust (abgeglichen) whether the corresponding control signal is also output to the first MEMS relay 2.

As a result, the use of other parameters may optionally be considered. For example, it is advantageous to check by the switching logic 6 before the closed state or the on state of the MEMS relay 2 is deduced from the very small voltage drop over the switch-on parts 3, 4: whether or not current flows through the switch-on parts 3,4 and thus through the current path 12. There is also the option that there is no voltage drop between the switch-on parts 3,4, although the MEMS relay 2 is switched to the conducting state, because no current flows through the current path 12, for example because it is not connected to a current source or a voltage source.

If it is recognized by the switching logic that the first MEMS relay 2 is not in the desired switching state, different measures can be taken. In particular, a signal is provided by which the upper electronic component, for example a microcontroller, is informed: the switching device 1 has a fault. It is also possible to activate the following by successive transitions of the control signal: releasing micromechanical components of MEMS relay 2 from possible mechanical blockages

The addition of a voltage measurement makes it possible to provide different diagnostic possibilities regarding the switching state of the first MEMS relay 2. This is particularly advantageous for applications where potential errors must be identified. The switching logic 6 is thus provided for detecting and evaluating the voltage applied to the switch-on parts 3,4 before and/or after the switching operation of the first MEMS relay 2.

Fig. 5 shows a switching device 1 according to a fourth embodiment of the present invention. The fourth embodiment of the invention here corresponds substantially to the third embodiment of the invention. The switching logic 6 has a communication interface 10 which enables information about the state of the switching device 1 to be called upon and/or the switching logic 6 to be actuated in order to switch the first MEMS relay 2 to the desired switching state. In this way, information about the switching state, the aging state, the overload of the MEMS relay 2, the temperature of the first MEMS relay 2, the current flowing through the MEMS relay 2 and/or the voltage applied to the switching-on parts 3,4 of the first MEMS relay 2 are in particular conveyed via the communication interface 10. The identified functional failure, in which case the switching state of the first MEMS relay 2 does not correspond to the desired switching state according to the applied control signal, can also be communicated via the communication interface 10.

The switching logic 6 may comprise a communication interface 10 to be able to configure a current, voltage or temperature or an associated threshold value. Thus, in particular, via the communication interface, it is possible to provide: at which thresholds for current, voltage or temperature the first MEMS relay 2 should react. It is also possible to operate the first MEMS relay 2 via the switching logic 6 and the communication interface 10 via an external component, for example a microcontroller. For example, the upper unit can be used to control to determine whether the MEMS relay 2 is in the correct switching state. Diagnostic functionality may be provided through the communication interface 10. For example, after the current path 12 has been switched off, the first MEMS relay 2 can be switched in a targeted manner in order to check whether the first MEMS relay 2 is still functional correctly.

It should be noted that the switching device 1 may also have such a communication interface 10 according to all embodiments of the invention.

Fig. 6 shows a schematic diagram of a switching device 1 according to a fifth embodiment of the present invention. Further, fig. 7 shows a switchgear 1 according to a sixth embodiment of the present invention. The fifth and sixth embodiments of the invention substantially correspond to the second and third embodiments of the invention, however, wherein the switching device 1 is arranged in the safety housing 13. The safety housing 13 preferably corresponds to a standardized safety housing. In this case, the switching logic 6 is advantageously supplied with the required operating voltage via a supply connection 14 arranged on the protective device housing 13. This supply of switching logic 6 is advantageous because otherwise if switching logic 6 is supplied via current path 12, an overvoltage occurring in current path 12 may lead to damage to switching logic 6. The corresponding supply of switching logic 6 is advantageous for all embodiments of the invention.

It is further preferred that an interface for the communication interface 10 is also provided on the safety device housing 13.

Optionally, according to any embodiment of the invention, the switching device 1 is arranged in a safety housing 13, which optionally has a supply connection 14 and/or a connection for the communication interface 10.

Fig. 8 shows a switching device 1 according to a seventh embodiment of the present invention. The switching device 1 according to the seventh embodiment of the invention here essentially corresponds to the sixth embodiment of the invention. However, the switching device 1 has a second MEMS relay 11, which second MEMS relay 11 is connected in series with the first MEMS relay 2 in a voltage path 12. The control switch-on 17 of the second MEMS relay 11 is also coupled to the switching logic 6. The second MEMS relay 11 is switched corresponding to the first MEMS relay 2. This means that when the first MEMS relay 2 is also switched to the non-conductive state, then the second MEMS relay 11 is switched to the non-conductive state. In a corresponding manner, when the first MEMS relay 2 is switched to the on-state, then the second MEMS relay 11 is also switched to the on-state.

In this case, the voltage sensor 9 is advantageously also provided to detect a first voltage drop between the switching elements 3,4 of the first MEMS relay 2 and, in addition, a second voltage drop between the switching elements of the second MEMS relay 11. The first voltage drop and the second voltage drop are here provided as measured values to the switching logic 6. The switching logic 6 is provided for determining the respective switching state of the MEMS relays 2, 11 on the basis of the first voltage drop and the detected second voltage drop and the control signals present for the MEMS relays 2, 11.

The arrangement of two MEMS relays 11 in series is advantageous for all embodiments of the invention. The redundancy in the switching off process is increased by the series connection of a plurality of MEMS relays 2, 11. In this case, a single malfunctioning MEMS relay does not result in the following: when requested by switching logic 6, current path 12 is not interrupted.

By detecting the first voltage drop and the second voltage drop, the MEMS relays 2, 11 can be inspected independently of each other and the switching process of the MEMS relays 2, 11 can be tested. For this purpose, it is particularly advantageous for the switching logic 6 to be coupled separately to the first MEMS relay 2 and the second MEMS relay 11, so that the first MEMS relay 2 and the second MEMS relay 11 can be actuated separately from one another. Thus, for example, during a test, in order to test the second MEMS relay 11, the first MEMS relay 2 may be placed in an on state, and the second MEMS relay 11 may be placed alternately in an on state or an off state. Accordingly, the first MEMS relay 2 may be tested in the opposite manner. In the case of a predefined identical switching state of the two MEMS relays 2, 11, the state of the respective MEMS relay 2, 11 can also be deduced from the difference between the first voltage drop and the second voltage drop.

Fig. 9 shows a battery management system 20 according to an eighth embodiment of the present invention. The battery system having the plurality of battery cells 31 to 38 is controlled by the battery management system 20. The battery cells 31 to 38 are connected in series with one another. The battery management system 20 includes control electronics 23 by which the voltages of the individual battery cells 31 to 38 are detected and optionally other functions, such as balancing of the battery cells 31 to 38, are provided. For this purpose, one positive and one negative electrode each of the battery cells 31 to 31 are connected to the control electronics 23 via a current path. In this way, for example, each positive electrode of the battery cells 31 to 38 is coupled to the control electronics 23 via a respective one of the current paths 40 to 48. Each of the current paths 40 to 48 is protected by a switching device 1 according to the previously described embodiment. This means that one switching device 1, 51 to 58 is arranged in each of the current paths 40 to 48. If an overvoltage occurs in one of the battery cells 31 to 38, the associated current path is broken and damage to the control electronics 23 is avoided. The switching logic of the individual switching devices 1, 51 to 58 can be combined here.

Fig. 10 shows a battery management system 20 according to a ninth embodiment of the present invention. The battery management system 20 here comprises a first control electronics 21 and a second control electronics 22. The first control electronics 21 are here the following electronics units: the electronic unit is supplied with an operating voltage even when the battery management system 20 is in an idle state. The second control electronics 22 is disconnected from the voltage supply in the idle state. The disconnection of the second control electronics 22 from the voltage supply takes place here by means of the switching device 1 according to the invention. To this end, the first control electronics 21 preferably comprises switching logic 6 and the first MEMS relay 2 is arranged between the plurality of battery cells 31 to 38 and the second control electronics 22 such that the current flow between the battery cells 31 to 38 and the second control electronics 22 can be disconnected by the first MEMS relay 2. Since the first control electronics 21, which are also supplied with voltage in the idle state, comprise the switching logic 6, it is possible to realize: in the event of the end of the idle state by switching the first MEMS relay 2, the second control electronics are in turn supplied with an operating voltage by the switching logic 6. This means that the switching device 1 according to the invention is advantageously used for switching a part of the battery management system 20, here the second control electronics 22, to an idle state. In this case, however, it is particularly advantageous if the switching logic 6 is arranged in the region of the battery management system 20 that is continuously supplied with the operating voltage. The operating voltage is here in particular the voltage supplied by one or more battery cells 31 to 38 managed by the battery management system 20.

Fig. 11 shows a battery management system 20 according to a tenth embodiment of the present invention. The tenth embodiment of the present invention corresponds here substantially to the eighth or ninth embodiment of the present invention. Here, in the tenth embodiment of the present invention, the second control electronic component 2 is coupled with the battery cells 31 to 38 through a plurality of current paths 40 to 48. Each of the current paths 40 to 48 has a MEMS relay, which can be switched by the first control electronics 21 in order to disconnect the second control electronics 22 from the poles of the last associated battery cell 31 to 38. This means that the switching device 1 does not necessarily have to operate as a safety device, but instead or additionally is switched by the switching logic 6 in order to disconnect the battery cells 31 to 38 from the second control electronics 22 in the idle state. The switching device 1 optionally comprises a temperature sensor 7, a current sensor 8 and/or a voltage sensor 9 or no sensor. Thus enabling: in the idle state of the battery management system 20, the battery cells 31 to 38 are completely disconnected from the second control electronics 22, or with the exception of the ground connection. It is thus achieved that the leakage current from the battery cells 31 to 38 into the second control electronics 22 is completely blocked during the idle state.

It is furthermore advantageous if the battery management system 20 according to any embodiment of the invention is arranged in a battery pack for an electric bicycle, wherein the battery pack has a housing, wherein a plurality of battery cells, in particular cylindrical round battery cells, are arranged in the housing. The battery cells here correspond in particular to the battery cells 31 to 38 described above.

Thus, the individual hardware functions can be switched by the respective associated MEMS relays 2, 51 to 58. In comparison with a semiconductor switch, electrical isolation can thus be achieved without leakage currents. In the on state, power losses are minimized and the switching state may optionally be maintained independently of the operation of the switching logic 6.

In addition to the above written disclosure, reference is explicitly made to the disclosure of fig. 1 to 9.

Claims

1. A switching device (1), the switching device (1) comprising:

-a first MEMS relay (2), the first MEMS relay (2) having two switch-on portions (3, 4) and at least one control-on portion (5), wherein an electrical connection between the switch-on portions (3, 4) can be switched by applying a control signal to the control-on portions, wherein the switch-on portions of the first MEMS relay (2) are arranged in a current path (12);

-a switching logic (6), the switching logic (6) being coupled to a control switch-on portion (5) of the first MEMS relay (2) for switching the first MEMS relay (2) by means of the control signal.

2. Switching device (1) according to claim 1, the switching device (1) comprising a temperature sensor (7), a current sensor (8) and/or a voltage sensor (9) coupled to the switching logic (6), wherein the switching device (1) is in particular configured as a safety device, preferably as an overload safety device or an overcurrent safety device.

3. The switching device (1) according to claim 2, the switching device (1) comprising:

-a temperature sensor (7), the temperature sensor (7) being coupled with the switching logic (6), and the temperature sensor (7) being arranged for detecting the temperature of the first MEMS relay (2);

-a current sensor (8), the current sensor (8) being coupled with the switching logic (6), and the current sensor (8) being arranged for detecting a current flowing through the current path (12);

wherein the switching logic (6) is provided for determining the aging state of the MEMS relay (2) and/or the overload of the MEMS relay (2) on the basis of the detected temperature and the detected current.

4. A switching device (1) according to claim 2 or 3, the switching device (1) comprising:

-a voltage sensor (9), the voltage sensor (9) being arranged for detecting a voltage drop between the switch-on portions (3, 4);

wherein the switching logic (6) is configured to determine, based on the detected voltage drop and the control signal: whether the first MEMS relay (2) is in a switching state corresponding to the control signal.

5. Switching device (1) according to any of claims 2 to 4, characterized in that,

the switching device (1) comprises a voltage sensor (9), wherein the voltage sensor (9) is provided for detecting a first voltage drop between the switch-on parts (3, 4) of the first MEMS relay (2) and for detecting a second voltage drop between the switch-on parts of the second MEMS relay (11);

wherein the switching logic (6) is configured to determine based on the detected first voltage drop, the detected second voltage drop and the control signal: which of the MEMS relays (2, 11) is in a switching state corresponding to the control signal.

6. Switching device (1) according to any one of claims 2 to 5, characterized in that:

the switching device (1) comprises a current sensor (8), the current sensor (8) being coupled with the switching logic (6), wherein the current sensor (8) is arranged for detecting a current flowing through the current path (12), wherein the switching logic (6) is arranged for: -in response to the detected current exceeding a predetermined threshold, breaking the electrical connection between the switch-on portions (3, 4) of the first MEMS relay (2); and/or

The switching device (1) comprises a temperature sensor (7), the temperature sensor (7) being coupled with the switching logic (6), wherein the temperature sensor (7) is provided for detecting the temperature of the first MEMS relay (2), wherein the switching logic (6) is provided for: in response to the detected temperature exceeding a predetermined threshold value, the electrical connection between the switch-on parts (3, 4) of the first MEMS relay (2) is broken.

7. The switching device (1) according to any one of claims 1 to 6, characterized in that the switching logic (6) comprises a communication interface (10) capable of implementing: -invoking information about the state of the switching device (1) and/or-manipulating the switching logic (6) for switching the first MEMS relay (2) to a desired switching state.

8. The switching device (1) according to any one of claims 1 to 7, characterized in that the switching device (1) further comprises a second MEMS relay (11), the switch-on part of the second MEMS relay (11) being arranged in series with the switch-on part (3, 4) of the first MEMS relay (2) in the current path (12), and the control-on part of the second MEMS relay (11) being likewise coupled with the switching logic (6), wherein the second MEMS relay (11) is switched by the switching logic (6) in correspondence with the first MEMS relay (2).

9. A battery management system (20), the battery management system (20) comprising a switching device (1) according to any one of claims 1 to 8.

10. The battery management system (20) of claim 9, the battery management system (20) comprising:

-a first control electronics component (21), by means of which first control electronics component (21) the operation of the battery management system (20) is controlled in a power saving mode, and which first control electronics component (21) is supplied with an operating voltage by means of at least one battery cell (31), wherein the first control electronics component (21) comprises the switching logic (6);

-a second control electronics component (22), the second control electronics component (22) being supplied with an operating voltage by at least one battery cell (31) via a current path (12), the current path (12) being switchable by means of the first MEMS relay (2);

wherein the first control electronics (21) are provided for disconnecting the second control electronics (22) from the operating voltage in the energy saving mode by switching the first MEMS relay (2).

11. The battery management system (20) of claim 10, wherein the second control electronics (22) is coupled with different battery cells (31-38) through a plurality of current paths (41-48), wherein each of the current paths (41-48) comprises one MEMS relay (51-58) to disconnect the second control electronics (22) from one or more of the battery cells (31-38), wherein the MEMS relay (51-58) is switchable by the first control electronics (21).

12. A battery pack for an electric bicycle, and having a battery management system according to any one of claims 9 to 11, wherein the battery pack has a housing, wherein a plurality of battery cells, in particular cylindrical round battery cells, are arranged in the housing.