Monitoring arrangement for an electrical component, semiconductor switch arrangement with monitoring function and power system

Description

State of the art

[0001] The present invention relates to a monitoring arrangement for an electrical component, a semiconductor switch arrangement with a monitoring function and an energy system with such a semiconductor switch arrangement.

[0002] Energy systems such as the electric drive systems of electrically powered vehicles, which include, for example, a traction battery and an electric drive motor, are known from the prior art. Electromechanical contactors are used, for example, to electrically connect and disconnect the traction battery from the drive motor. These contactors are monitored for fault conditions such as sticking and / or welding of electrical contacts by means of a diagnostic function. Such diagnostic functionalities are used, for example, when the contactors are opened. If a fault condition is detected, it is accordingly possible to protect the electrical energy system by means of a suitable fault response.

[0003] Furthermore, it is known to use MOSFETs in a so-called "back-to-back" arrangement instead of contactors to connect and disconnect electrical power sources and electrical consumers.

[0004] US2015198635 A1 describes a device for measuring a voltage, comprising a first circuit and a second circuit, wherein the first circuit is connected to one or more nodes and generates an matching signal based on a measurement, and wherein the second circuit is configured to generate a comparison signal based on a comparison of a first voltage and a third voltage.

[0005] Document WO 2020 / 216486 A1 discloses a disconnect switch with bidirectional clamping, which is used in particular in the electrical system of a motor vehicle.

[0006] Document EP 3 489 707 A1 discloses a device for measuring electrical parameters, comprising a voltage test input terminal, a common input terminal and a reference signal circuit.

[0007] Document DE 24 27 785 C2 discloses a circuit arrangement for a measuring amplifier. Disclosure of the invention

[0008] According to a first aspect of the present invention, a monitoring arrangement for an electrical component according to claim 1 is proposed. The monitoring arrangement comprises: an electrical component, which is, for example, an electronic switch (e.g., a bipolar transistor, a MOSFET, etc.) and / or an electromechanical switch (e.g., a relay, a contactor, etc.) and / or a semiconductor device such as a diode and / or a measuring resistor and / or an electrical circuit, etc.comprises a first voltage divider with a first resistor and a second resistor, a second voltage divider with a third resistor and a fourth resistor, a first switch, a second switch, which are, for example, semiconductor switches or electromechanical switches, an input terminal, an output terminal, a reference potential terminal, which is, for example, a ground terminal of the monitoring arrangement, a measuring device, which is, for example, an A / D converter, and an evaluation unit, wherein the evaluation unit is, for example, designed as an ASIC, FPGA, processor, digital signal processor, microcontroller, or similar.

[0009] The electrical component is connected between the input terminal and the output terminal of the monitoring arrangement.

[0010] Furthermore, the first voltage divider is connected between the input terminal and the reference potential terminal, the second voltage divider is connected between the output terminal and the reference potential terminal, the second switch is connected between the input terminal and the output terminal, and the first switch is connected between the input terminal and a junction point of the first voltage divider and the second switch. Alternatively, the second switch is connected between the output terminal and a junction point of the second voltage divider and the second switch. As a further alternative, it is possible to additionally place a third switch in the path where the second switch is not located.

[0011] A first measuring terminal of the measuring device is connected to a connection point of the third resistor and the fourth resistor of the second voltage divider, a second measuring terminal of the measuring device is connected to a connection point of the first resistor and the second resistor of the first voltage divider, and the measuring device is configured to measure a voltage at the first measuring terminal and at the second measuring terminal, respectively, and to transmit a result of the respective measurements to the evaluation unit.

[0012] The evaluation unit is configured to determine a correction factor for adjusting the voltage divider between the first and second voltage dividers. This is achieved by means of a control signal from the evaluation unit, which is connected to both the first and second switches, opening the first switch and closing the second switch. Furthermore, the evaluation unit is configured to determine the state of the electrical component based on an evaluation of the voltage difference between the first and second measurement inputs of the measuring device, corrected by the correction factor. This is achieved by means of a control signal from the evaluation unit, closing the first switch and opening the second switch.

[0013] The monitoring arrangement according to the invention, based on the configuration described above, offers, among other advantages, the simple and, in particular, cost-effective measure of precise voltage differences, especially at higher voltage levels (e.g., 48 V or in the high-voltage range), between the input and output terminals. This enables particularly reliable monitoring of the electrical component under observation. A further important advantage arises from the fact that precise voltage measurement is possible in the operational state of the electrical component.a higher-level system employing the electrical component can be used, since temperature-related resistance changes in the two voltage dividers, especially those caused by operation, can be continuously compensated by means of continuously determined correction factors.

[0014] The dependent claims describe preferred embodiments of the invention.

[0015] Preferably, the first and second voltage dividers are symmetrically constructed with respect to their resistance values, such that the resistors of the first and second voltage dividers that are connected to the reference potential terminal have essentially the same resistance values, and the other resistors of the two voltage dividers also have essentially the same resistance values. "Essentially" means that manufacturing tolerances of the resistance values ​​of corresponding resistors are included.Due to the correction of resistance deviations between the voltage dividers according to the invention, it is also advantageously possible to use inexpensive resistors with higher tolerances, as long as the compensation of static and / or dynamic deviations in resistance values ​​is not significantly impaired by a predetermined maximum measuring range and / or resolution of the measuring device. Alternatively or additionally, the monitoring arrangement is configured to monitor voltages up to 60 V, preferably up to 400 V, and particularly preferably up to 800 V.

[0016] In an advantageous embodiment of the present invention, the frequency of determining the correction factor and / or measuring the voltage difference corrected by means of the correction factor is adapted as a function of a rate of change of a voltage measured between the input terminal and the reference potential terminal and / or a current measured between the input terminal and the output terminal and / or a temperature in the area of ​​the electrical component and / or an aging of the electrical component.This offers the advantage that, with a low rate of change of the aforementioned quantities, the computational load and / or energy consumption in the evaluation unit according to the invention is low, while ensuring that rapid changes of the aforementioned quantities are always detected by means of a higher measurement frequency, so that deviations in the resistance values ​​of the two voltage dividers caused by these quantities can be compensated before these deviations negatively affect a required or predefined accuracy of the monitoring of the two semiconductor switches.

[0017] In a further advantageous embodiment of the present invention, if a fault condition of the electrical component is detected, fault handling is initiated by the evaluation unit, which in particular results in an electrical isolation of the output terminal from the input terminal. Depending on the design of the electrical component, this isolation is achieved, for example, based on the electrical component itself (at least by means of a potentially still functional part of the electrical component) and / or by a further isolation device, which is configured to isolate the input terminal and the output terminal from each other independently of the electrical component. Alternatively, instead of isolating the input terminal from the output terminal, it is also conceivable to reduce the power drawn at the output terminal and / or to put a higher-level system into an emergency running mode as soon as a fault condition is detected.Furthermore, based on the precise voltage measurement provided by the monitoring arrangement according to the invention, it is possible to distinguish between non-critical fault conditions (e.g. fault conditions that do not lead to a critical temperature increase in the electrical component) and critical fault conditions within the electrical component, so that correspondingly more differentiated fault reactions can be carried out.

[0018] Preferably, the correction factor is determined only when a current between the input terminal and the output terminal exceeds a predefined current threshold, so that sufficient accuracy of the measurement is ensured due to the associated higher voltage drop across the electrical component or the associated higher voltage difference at the measuring device.

[0019] In a further advantageous embodiment of the present invention, at least one resistor of the first voltage divider and / or at least one resistor of the second voltage divider is arranged outside a region in which there is a substantially uniform heating of the resistors of the two voltage dividers due to a substantially uniform ambient temperature.In other words, the monitoring arrangement according to the invention allows for greater flexibility in the arrangement of the resistors of the two voltage dividers, since the effects on the respective resistance values ​​due to temperature differences between the respective resistors can be compensated for by the (continuous) calibration, especially for temperature differences that would lead to distorted measurement results in the prior art and which would correspondingly reduce the reliability of a monitoring function based on a voltage divider not compensated according to the invention.

[0020] Preferably, the evaluation unit is configured to always control the first and second switches in such a way that a short circuit is never generated between the input and output terminals via the first and second switches. This ensures, particularly when the monitoring arrangement according to the invention is used in conjunction with higher power applications, that connections designed as measuring lines (i.e., lines and / or conductor tracks designed for low power) to and from the first and second switches are not damaged in the event of a short circuit across these measuring lines and the respective switches. Alternatively or additionally, the evaluation unit is configured to open the first switch upon detecting a 'standby mode' of a system using the monitoring arrangement.This makes it possible to minimize the power consumption of a system using the monitoring arrangement.

[0021] According to a second aspect of the present invention, a semiconductor switch arrangement with a monitoring function is proposed, which includes a monitoring arrangement according to one of the preceding claims. The electrical component comprises a first semiconductor switch with a first inverse diode and a second semiconductor switch with a second inverse diode, wherein the first semiconductor switch and the second semiconductor switch are preferably MOSFETs, more preferably "normally closed" MOSFETs, and particularly preferably identically configured MOSFETs, without thereby limiting the semiconductor switches to the aforementioned configurations. The first semiconductor switch and the second semiconductor switch are connected in series between the input terminal and the output terminal such that the first inverse diode and the second inverse diode are connected in antiseries (also referred to as a "back-to-back" arrangement).Furthermore, the first and second semiconductor switches are configured to enable and interrupt current flow between the input and output terminals based on a control signal. Due to the use of semiconductor switches with inverting diodes, both unidirectional current flow (when one of the two semiconductor switches is open while the other is closed) and bidirectional current flow (when both semiconductors are open) are possible. Regarding the arrangement of the two semiconductor switches, they can be connected in series, with their source terminals connected, or in series, with their drain terminals connected.The first and second semiconductor switches are controlled, for example, by means of the evaluation unit according to the invention or by means of a separate control unit. The features, combinations of features, and the advantages arising therefrom correspond to those described in connection with the first-mentioned aspect of the invention in such a way that, to avoid repetition, reference is made to the above explanations.

[0022] Particularly advantageously, determining the state of the first semiconductor switch and / or the second semiconductor switch includes detecting a short circuit present in the first semiconductor switch and / or the second semiconductor switch and / or a deviation of an actual switching state from a target switching state of the first semiconductor switch and / or the second semiconductor switch. In a case where the evaluation unit itself is configured to control the first semiconductor switch and the second semiconductor switch, the evaluation unit preferably uses internal status information representing the respective target switching states to determine deviations from these states.In a case where a control unit other than the evaluation unit is set up to control the two semiconductor switches, the evaluation unit preferably receives the status information about the respective target switching states from this control unit.

[0023] In a further advantageous embodiment of the present invention, at least one further series circuit consisting of a third semiconductor switch and a fourth semiconductor switch is connected in parallel to the series circuit consisting of the first semiconductor switch and the second semiconductor switch, so that, for example, higher power levels can be switched than with only two semiconductor switches.

[0024] According to a third aspect of the present invention, an energy system is proposed comprising a semiconductor switch arrangement as described above, a battery, in particular a vehicle battery (e.g., a traction battery), which is connected between the input terminal and the reference potential terminal, and an electrical load, in particular an electrical load of a vehicle (e.g., a drive motor), which is connected between the output terminal and the reference potential terminal. Based on the semiconductor switch arrangement according to the invention, such an energy system is configured to connect the battery and the electrical load and, for example, to disconnect them in a fault state or a standby state, while ensuring reliable monitoring of the functionality of the respective semiconductor switches of the semiconductor switch arrangement.The features, combinations of features and the advantages resulting from them correspond so clearly to those described in connection with the first and second aspects of the invention that reference is made to the above statements to avoid repetition. Brief description of the drawings

[0025] Exemplary embodiments of the invention are described in detail below with reference to the accompanying drawing. The drawings show: Figure 1 shows a circuit diagram of a semiconductor switch arrangement according to a first embodiment according to the invention; and Figure 2 shows a circuit diagram of an energy system according to the invention with a semiconductor switch arrangement according to a second embodiment. Embodiments of the invention

[0026] Figure 1Figure 1 shows a circuit diagram of a semiconductor switch arrangement according to a first embodiment of the invention, which is based on a monitoring arrangement according to the invention. The semiconductor switch arrangement has an input terminal 30, an output terminal 32, and a ground terminal 34. A first MOSFET 10 and a second MOSFET 15 are arranged back-to-back between the input terminal 30 and the output terminal 32. The two MOSFETs 10 and 15 are controlled by an evaluation unit 50, which is electrically connected to the respective control inputs of the two MOSFETs 10 and 15. The semiconductor switch arrangement also has a first voltage divider 20, which consists of a first resistor R1 and a second resistor R2, and a second voltage divider 25, which consists of a third resistor R3 and a fourth resistor R4.The resistance value of the first resistor R1 corresponds essentially to the resistance value of the third resistor R3, and the resistance value of the second resistor R2 corresponds essentially to the resistance value of the fourth resistor R4. In conjunction with a measuring device, which here is designed as an analog-to-digital converter (ADC) 40, the two voltage dividers 20 and 25 form a measuring bridge. For this purpose, the ADC 40 is electrically connected via a second measuring terminal 44 to a junction point between the first resistor R1 and the second resistor R2, and via a first measuring terminal 42 to a junction point between the third resistor R3 and the fourth resistor R4. Furthermore, the ADC 40 is connected to the evaluation unit 50, enabling the evaluation unit 50 to receive information about the respective voltage measurements of the ADC 40 at the first measuring terminal 42 and at the second measuring terminal 44.Furthermore, the semiconductor switch arrangement has a first switch S1 and a second switch S2, whose respective control inputs are connected to the evaluation unit 50 via information technology.

[0027] Based on the configuration described above, the semiconductor switch arrangement is set up to perform a precise and continuously calibratable voltage measurement as described above, so that a reliable verification of the intended switching states and any short circuits present in the two MOSFETs 10, 15 can be carried out based on such a voltage measurement. The first switch S1 is shown here as being in an open state, while the second switch S2 is shown here as being in a closed state. Due to these states, the two voltage dividers 20, 25 are consequently at the same potential, so that the two voltage dividers 20, 25 can be adjusted by the A / D converter 40 based on their respective voltage measurements.

[0028] In the event of a detected fault condition, it is possible, for example, to bring about a separation of the input terminal 30 from the output terminal 32 by controlling the two MOSFETs 10, 15.

[0029] Furthermore, it is possible that a correction factor used for the calibration of the voltage dividers 20, 25 is only determined if a predefined current threshold is exceeded by a current flowing between the input terminal 30 and the output terminal 32.

[0030] Furthermore, it is possible that at least some of the resistors R1, R2, R3, R4 are arranged separately from each other, since different temperature influences on the resistors R1, R2, R3 R4 can be advantageously compensated by means of the semiconductor switch arrangement according to the invention.

[0031] Preferably, the first switch S1 and the second switch S2 are always controlled in such a way that a short circuit between the input terminal 30 and the output terminal 32 is never generated via the first switch S1 and the second switch S2, and that in the case of a 'quiet mode' of a system using the semiconductor switch arrangement, the first switch S1 is always opened.

[0032] Figure 2 The diagram shows a circuit diagram of an energy system according to the invention with a semiconductor switch arrangement according to a second embodiment. The semiconductor switch arrangement in Figure 2 largely corresponds to the one in Figure 1 The described semiconductor switch arrangement is therefore only described below to avoid repetition, highlighting the differences to Figure 1 be described.

[0033] In Figure 2The semiconductor switch arrangement according to the invention additionally comprises a third MOSFET 60 and a fourth MOSFET 65, which are also arranged in a back-to-back configuration and are connected in parallel to the series connection of the first MOSFET 10 and the second MOSFET 15. The MOSFETs 60 and 65 are also controlled by the evaluation unit 50. This enables switching at higher power levels than in the Figure 1 shown first embodiment of the semiconductor switch arrangement.

[0034] Furthermore, it lies in Figure 2For example, a closed state of the first switch S1 and for example a closed state of the second switch S2 are assumed, so that in this state it is possible to determine an input voltage between the input terminal 30 and the ground terminal 34 and an output voltage between the output terminal 32 and the ground terminal 34 on the basis of the adjusted voltage dividers 20, 25 or the determined correction factor.

[0035] The energy system, which here is an energy system of an electrically powered vehicle, has a traction battery 70, which is connected between the input terminal 30 and the ground terminal 34, and a drive motor 80, which is connected between the output terminal 32 and the ground terminal 34.

Claims

1. Monitoring arrangement for an electrical component, having: • an electrical component (10, 15), • a first voltage divider (20) with a first resistor (R1) and a second resistor (R2), • a second voltage divider (25) with a third resistor (R3) and a fourth resistor (R4), • a first switch (S1), • a second switch (S2), • an input connection (30), • an output connection (32), • a reference potential connection (34), • a measuring apparatus (40), and • an evaluation unit (50), wherein • the electrical component (10, 15) is connected between the input connection (30) and the output connection (35), the first voltage divider (20) is connected between the input connection (30) and the reference potential connection (34), • the second voltage divider (25) is connected between the output connection (32) and the reference potential connection (34), • the second switch (S2) is connected between the output connection (32) and a connecting point of the first switch (S1), • the first switch (S1) ∘ is connected between the input connection (30) and a connecting point of the first voltage divider (20) and the second switch (S2), or ∘ is connected between the output connection (32) and a connecting point of the second voltage divider (25) and the second switch (S2), • a first measuring connection (42) of the measuring apparatus (40) is connected to a connecting point of the third resistor (R3) and the fourth resistor (R4) of the second voltage divider (25), • a second measuring connection (44) of the measuring apparatus (40) is connected to a connecting point of the first resistor (R1) and the second resistor (R2) of the first voltage divider (20), • the measuring apparatus (40) is configured to measure a respective voltage at the first measuring connection (42) and at the second measuring connection (44) and to transmit a result of the respective measurements to the evaluation unit (50), and • the evaluation unit (50) is configured ∘ to ascertain a correction factor for an alignment between the first voltage divider (20) and the second voltage divider (25), while the first switch (S1) is opened and the second switch (S2) is closed by means of an actuation by the evaluation unit (50), and ∘ to ascertain a state of the electrical component (10, 15) on the basis of an evaluation of a voltage difference, which is corrected by means of the correction factor, between the first measuring input (42) and the second measuring input (44) of the measuring apparatus (40), while the first switch (S1) is closed and the second switch (S2) is opened by means of an actuation by the evaluation unit (50), wherein a frequency of ascertaining the correction factor and / or measuring the voltage difference corrected by means of the correction factor is adjusted depending on ∘ a rate of change • a voltage measured between the input connection (30) and the reference potential connection (34), and / or • a current measured between the input connection (30) and the output connection (32), and / or • a temperature in the region of the electrical component (10, 15), and / or o ageing of the electrical component (10, 15).

2. Monitoring arrangement according to Claim 1, wherein • the first voltage divider (20) and the second voltage divider (25) are of symmetrical design, and / or • the monitoring arrangement is configured to monitor voltages up to 60 V, preferably up to 400 V and particularly preferably up to 800 V.

3. Monitoring arrangement according to either of the preceding claims, wherein, if a fault state of the electrical component (10, 15) is ascertained by means of the evaluation unit (50), fault handling is initiated, which in particular causes the output connection (32) to be electrically isolated from the input connection (30).

4. Monitoring arrangement according to one of the preceding claims, wherein the correction factor is ascertained only if a current between the input connection (30) and the output connection (32) exceeds a predefined current threshold value.

5. Monitoring arrangement according to one of the preceding claims, wherein at least one resistor (R1, R2) of the first voltage divider (20) and / or at least one resistor (R3, R4) of the second voltage divider (25) is arranged outside a region in which there is substantially uniform heating of the resistors of the two voltage dividers (20, 25) due to a substantially uniform ambient temperature.

6. Monitoring arrangement according to one of the preceding claims, wherein the evaluation unit (50) is configured • to continuously actuate the first switch (S1) and the second switch (S2) by means of the evaluation unit (50) [figures 1 and 2] in such a way that a short circuit is not generated between the input connection (30) and the output connection (32) via the first switch (S1) and the second switch (S2) at any time, and / or • to open the first switch (S1) in response to ascertaining an idle mode of a system using the monitoring arrangement.

7. Semiconductor switch arrangement with a monitoring function, having a monitoring arrangement according to one of the preceding claims, wherein • the electrical component has a first semiconductor switch (10) with a first inverse diode and a second semiconductor switch (15) with a second inverse diode, and • the first semiconductor switch (10) and the second semiconductor switch (15) ∘ are connected in series between the input connection (30) and the output connection (32) in such a way that the first inverse diode and the second inverse diode are connected in antiseries, and ∘ are configured to enable and to interrupt a flow of current between the input connection (30) and the output connection (32) on the basis of an actuation.

8. Semiconductor switch arrangement according to Claim 7, wherein ascertaining the state of the first semiconductor switch (10) and / or of the second semiconductor switch (15) includes ascertaining • a short circuit present in the first semiconductor switch (10) and / or in the second semiconductor switch (15), and / or • a deviation of an actual switching state from a target switching state of the first semiconductor switch (10) and / or of the second semiconductor switch (15).

9. Semiconductor switch arrangement according to Claim 7 or 8, wherein at least one further series circuit comprising a third semiconductor switch (60) and a fourth semiconductor switch (65) is connected in parallel with the series circuit comprising the first semiconductor switch (10) and the second semiconductor switch (15).

10. Energy system, having: • a semiconductor switch arrangement according to one of Claims 7 to 9, • a battery (70), in particular a vehicle battery, which is connected between the input connection (30) and the reference potential connection (34), and • an electrical load (80), in particular an electrical load of a vehicle, which is connected between the output connection (32) and the reference potential connection (34).