Monitoring device and method for monitoring the closing state of a battery switch, inverter device, electric axle drive and motor vehicle

Abstract

A monitoring device (100) for monitoring the closed state of a battery switch (105) comprises a power source (140), a diode (130) connected in series with the power source, and an evaluation circuit (150). The power source (140) and the diode (130) are connected in parallel with the battery switch (105). The power source (140) is configured to generate a current or voltage between a first switch terminal (106) and a second switch terminal (108) of the battery switch (105). The evaluation circuit (150) is configured to provide an evaluation signal (195) indicating the closed state of the battery switch (105) by means of a voltage potential that can be tapped between the diode (130) and the power source (140).

Description

[0001] The present invention relates to a monitoring device and a method for monitoring a closing state of a battery switch, to a converter device, to an electric axle drive and to a motor vehicle.

[0002] An inverter's DC link can be discharged using passive or active discharge. A battery switch can be placed between a battery and the DC link.

[0003] Against this background, the present invention provides an improved monitoring device and an improved method for monitoring the closed state of a battery switch, an improved converter device, an improved electric axle drive, and an improved motor vehicle according to the main claims. Advantageous embodiments emerge from the subclaims and the following description.

[0004] The advantages achievable with the approach presented here are, in particular, that a monitoring device is created that can reliably and quickly monitor the closing state of a battery switch.

[0005] A monitoring device is provided for monitoring the closed state of a battery switch. The battery switch has a first switch terminal for connecting the battery switch to a pole of a battery and a second switch terminal for connecting the battery switch to a pole of an intermediate circuit. The monitoring device has a series circuit consisting of a power source and a diode and furthermore an evaluation circuit. The series circuit is connected in parallel to the battery switch. The power source has a first power source terminal and a second power source terminal. The power source is designed to generate a current flow or a voltage between the first switch terminal of the battery switch and the second switch terminal of the battery switch. The diode has a first diode terminal and a second diode terminal.The first diode terminal is connected to the second power source terminal. The evaluation circuit is configured to provide an evaluation signal using a voltage potential applied to the first diode terminal, which signal indicates the closed state of the battery switch.

[0006] By detecting the closed state of the battery switch, it is possible to determine, for example, whether a command to decouple the battery as an energy storage device from the DC link has been successfully executed. This can provide advantages for actively discharging the DC link. The approach presented here can therefore also be understood as monitoring battery decoupler.

[0007] The battery switch can be arranged in a line connecting the battery to the intermediate circuit, similar to known battery switches. Depending on the design, the battery terminal and the intermediate circuit terminal can represent either both positive or both negative poles. Using the power source, a test voltage can be applied to the battery switch, or a test current can be passed through the battery switch to detect its closed state. This can take advantage of the fact that the magnitude of a voltage potential at a tapping point, for example, at a junction between the diode and the power source, is dependent on the closed state of the battery switch, making it suitable for generating the evaluation signal.The evaluation circuit can be designed to provide the evaluation signal depending on the magnitude of the voltage potential occurring at the tapping point either with a first value indicating a closed state of the battery switch or with a second value indicating an open state of the battery switch.

[0008] The diode can have a cathode and an anode. The first diode terminal can be the anode, and the second diode terminal can be the cathode. By polarizing the diode accordingly, a battery voltage can be blocked.

[0009] The evaluation circuit may comprise a comparator. The comparator may have a first input, a second input, and an output. The comparator may be connected to the first diode terminal via the first input and to a reference voltage terminal via the second input. The comparator may be configured to provide the evaluation signal at the output. The comparator can reliably and quickly compare a voltage potential dependent on the closed state of the battery switch with a reference voltage potential of the reference voltage terminal.

[0010] The first power source terminal can be connected to the second switch terminal, and the second diode terminal can be connected to the first switch terminal. Such a configuration is advantageous when the battery switch is arranged between a positive terminal of the battery and a positive terminal of the intermediate circuit.

[0011] Alternatively, the first power source terminal can be connected to the first switch terminal, and the second diode terminal can be connected to the second switch terminal. Such a design is advantageous when the battery switch is arranged between a negative terminal of the battery and a negative terminal of the intermediate circuit.

[0012] The energy source can be a current source. Alternatively, the energy source can be a voltage source. This simplifies the selection of a suitable energy source.

[0013] The energy source may have a first resistor, a second resistor, and a supply voltage potential. The first resistor may be connected between the supply voltage potential and the second energy source terminal of the energy source. The second resistor may be connected between the first energy source terminal and the second energy source terminal of the energy source. In this way, the energy source can be easily constructed as a voltage source with a resistance divider.

[0014] The series circuit may include a third resistor. The third resistor may be integrated into the series circuit at a suitable position. The third resistor may be high-impedance to enable safe operation of the monitoring device, for example, when recuperation is expected.

[0015] The diode can be connected between the third resistor and the power source. This can enable reliable operation of the monitoring device.

[0016] The monitoring device may include the battery switch. The battery switch may include the first switch terminal for connecting the battery switch to the battery pole and the second switch terminal for connecting the battery switch to the intermediate circuit pole. For example, the monitoring device including the battery switch may be provided as a circuit unit.

[0017] A converter device comprises an embodiment of a monitoring device mentioned herein. In addition, the converter device comprises an intermediate circuit and a converter device for converting a battery voltage into a drive voltage. The intermediate circuit is connected between the battery switch and the converter device. The converter device can be a power converter, for example, a converter or an inverter.

[0018] An electric axle drive for a motor vehicle comprises an electric machine, a transmission device, and an embodiment of a converter device mentioned herein. Using the converter device, an electric current required to operate the electric machine can be provided. Using the transmission device, a torque provided by the electric machine can be converted into a drive torque for driving at least one wheel of the motor vehicle. The transmission device can have a gearbox for reducing the speed of the electric machine and optionally a differential.

[0019] Accordingly, a motor vehicle may comprise a said converter device and additionally or alternatively a said electric axle drive.

[0020] A method for monitoring a closed state is provided for a battery switch. The battery switch has a first switch terminal for connecting the battery switch to a pole of a battery and a second switch terminal for connecting the battery switch to a pole of an intermediate circuit. The method is carried out using a series circuit having a power source and a diode and using an evaluation circuit. The series circuit is connected in parallel to the battery switch. The power source has a first power source terminal and a second power source terminal. The diode has a first diode terminal and a second diode terminal, wherein the first diode terminal is connected to the second power source terminal. The method comprises a generating step and a providing step.In the generating step, a current flow or a voltage is generated between the first switch terminal of the battery switch and the second switch terminal of the battery switch. The generating step is carried out using the energy source. In the providing step, an evaluation signal is provided that indicates the closed state of the battery switch. The providing step is carried out using the evaluation circuit and a voltage potential applied to the first diode terminal.

[0021] The invention is explained in more detail by way of example with reference to the accompanying drawings. They show: Fig. 1 is a circuit diagram of an embodiment of a monitoring device; Fig. 2 a circuit diagram of an embodiment of a monitoring device; Fig. 3 a circuit diagram of an embodiment of a monitoring device; Fig. 4 a circuit diagram of an embodiment of a monitoring device; Fig. 5 a schematic representation of an embodiment of a motor vehicle; and Fig. 6 a flowchart of an embodiment of a method for monitoring a closing state of a battery switch.

[0022] In the following description of preferred embodiments of the present invention, the same or similar reference numerals are used for the elements shown in the various figures and having a similar effect, whereby a repeated description of these elements is omitted.

[0023] Fig. 1 shows a circuit diagram of an embodiment of a monitoring device 100. The monitoring device 100 is configured to monitor the closed state of a battery switch 105. According to the embodiment shown, the battery switch 105 is used to connect or disconnect a battery 110 to an intermediate circuit 120. A first switch terminal 106 of the battery switch 105 is connected to a first pole 102 of the battery 110, and a second switch terminal 108 of the battery switch 105 is connected to a first pole 104 of the intermediate circuit 120.

[0024] The monitoring device 100 is merely interconnected by way of example and is illustrated as a component of a converter device 175. The converter device 175 has a converter device 185 for converting or converting a battery voltage of the battery 110 or an intermediate circuit voltage of the intermediate circuit 120 into a drive voltage, which can be used, for example, to operate an electrical machine.

[0025] According to one embodiment, the battery 110 serves as the main energy storage device in a battery-operated electric drive train of a vehicle. The energy stored in the battery 110 is suitably converted by the converter device 175 and delivered to an electric machine, see, for example, Fig. 5. For this purpose, the converter device 175 requires a buffer storage device, which is implemented in the intermediate circuit 120. A supply line from the battery 110 to the intermediate circuit 120 is decoupled via a mechanical or electrical switch, here the battery switch 105, so that the converter device 185 can be de-energized despite the battery 110 being charged. In the event of a fault, the battery 110 is decoupled from the rest of the system, and the voltage at the intermediate circuit 120 is discharged via a discharge. For safety reasons, there are two discharge paths. A passive discharge is implemented as an ohmic voltage divider, which is applied between the positive and negative poles of the intermediate circuit. To keep the energy loss in the passive discharge low, it takes a very long time, for example, six minutes, until the voltage at the intermediate circuit capacitor has been sufficiently discharged after the battery 110 has been decoupled, typically to less than 60 volts.A second measure is implemented as active discharge. This is a function that can be activated as needed, allowing the intermediate circuit 120 to be sufficiently discharged within a short period of time, for example, within two seconds, after the battery 110 is disconnected. Due to the otherwise very high power loss, this path is not permanently active and is only activated once the battery 110 is safely disconnected.

[0026] If the condition arises that the battery switch 105 does not reliably disconnect the battery 110, i.e. the battery 110 is still connected to the intermediate circuit 120 despite a command to disconnect, the active discharge is not carried out or must be stopped again within a very short time.

[0027] To reliably detect the closed state of the battery switch 105, the monitoring device 100 has a series circuit 135 consisting of a diode 130 and a power source 140, as well as an evaluation circuit 150. The series circuit 135 consisting of the diode 130 and the power source 140 is connected in parallel to the battery switch 105.

[0028] According to different embodiments, the monitoring device 100 comprises only the series circuit 135 and the evaluation circuit 150 or additionally also the battery switch 105.

[0029] The energy source 140 has a first energy source terminal 142 and a second energy source terminal 144. The energy source 140 is configured, for example, as a current source to generate a current flow between the first switch terminal 106 of the battery switch 105 and the second switch terminal 108 of the battery switch 105. For this purpose, the first energy source terminal 142 is connected, for example, to the second switch terminal 104. A ground potential terminal 160 is connected, merely by way of example, between the first energy source terminal 142 and the second switch terminal 108.

[0030] Diode 130 has a first diode terminal 132 and a second diode terminal 134. The first diode terminal 132 is, for example, an anode, and the second diode terminal 134 is a cathode. The first diode terminal 132 is connected to the second energy source terminal 144, and the second diode terminal 134 is connected, for example, to the first switch terminal 106. The diode 130 is therefore reverse-biased toward the first switch terminal 108.

[0031] The evaluation circuit 150 is configured to provide an evaluation signal 195 using a voltage potential present at a tapping point. The evaluation signal 195 indicates the closed state of the battery switch 105. The tapping point is located, for example, on a connecting line connecting the first diode terminal 132 to the second energy source terminal 144. Thus, the voltage signal used to generate the evaluation signal 195 corresponds to the voltage potential present at both the first diode terminal 132 and the second energy source terminal 144. The evaluation circuit 150 has a suitable circuit for generating the evaluation signal 195 depending on the magnitude of the voltage potential.

[0032] According to one embodiment, the evaluation circuit 150 comprises a comparator 158. The comparator 158 has a first input 152, a second input 154, and an output 156. The comparator 158 is connected, for example, to the first diode terminal 132 via the first input 152. The comparator 158 is connected, for example, to a reference voltage terminal 180 via the second input 154. The comparator 158 is designed to provide the evaluation signal 195 at the output 156 using a voltage potential applied to the first input 152 and a reference voltage potential of the reference voltage terminal 180. According to one embodiment, the comparator 158 is also connected to ground.

[0033] According to one embodiment, the first pole 102 of the battery 110 and the first pole 104 of the intermediate circuit 120 are each designed as a positive pole.

[0034] When the battery switch 105 is closed, current flows from the energy source 140 in the flow direction 190 to the first switch terminal 106 and through the battery switch 105 to the second switch terminal 108. In this closed state of the battery switch 105, the battery 110 is coupled to the intermediate circuit 120.

[0035] The intermediate circuit 120 can be quickly discharged, for example, by means of an active discharge. The active discharge is only carried out when the battery 110 is decoupled from the intermediate circuit 120. For this purpose, the battery switch 105 is opened, preventing current flow through the battery switch 105. The diode 130 blocks the current flow in the reverse direction. Instead, a voltage from the energy source 140 is present. This voltage is detected by the evaluation circuit 150, for example by the comparator 158, and used to provide the evaluation signal 195. The evaluation signal 195 indicates, for example, via a first signal state, that the battery 110 is decoupled. The active discharge of the intermediate circuit 120 can thus take place, for example.

[0036] The approach presented here presents a method for testing the decoupling of battery 110 from the intermediate circuit 120 before active discharge is initiated. This test can be used to exclude the possibility of active discharge being initiated while the battery 110 is connected. This prevents the occurrence of high energy losses and allows for circuit components to be dimensioned entirely in a function-oriented manner.

[0037] The approach presented here is based on the concept of continuity testing. According to one embodiment, a gate driver of a power electronics system typically includes a desaturation detection circuit for detecting a short circuit. The desaturation detection procedure is applied for a continuity test. For this purpose, the monitoring device 100, which can also be referred to as a circuit, is attached to terminals 106, 108 of the battery switch 105 for disconnecting the battery 110.

[0038] According to one embodiment, Fig. 1 shows the monitoring device 100 for detecting the disconnection of the intermediate circuit 120. If the battery switch 105 is closed, the current from the energy source 104, which can also be referred to as iDESAT, can flow via the diode 130 and the battery switch 105, and no voltage is built up. If the switch is open, the diode 130 blocks the reverse voltage of the battery 110, and the current iDESAT does not flow. The maximum available voltage of the energy source 104 is present at the output of the energy source 104 and is detected by the comparator 158. The evaluation signal 195, which can also be referred to as vID, indicates whether the battery 110 is disconnected. If the command to disconnect the battery 110 is issued and the switch cannot open due to an error, this is detected, and the active discharge is not activated.

[0039] Fig. 2 shows a circuit diagram of an embodiment of a monitoring device 100. The monitoring device 100 is similar to the monitoring device 100 of Fig. However, Figure 1 is adapted to the case where the battery switch 105 is arranged between a second pole 202 of the battery 110 and a second pole 204 of the intermediate circuit 120, wherein the second poles 202, 204 are each designed as negative poles. Therefore, the first energy source terminal 142 of the energy source 140 is connected to the first switch terminal 106, and the second diode terminal 134 of the diode 130 is connected to the second switch terminal 108.

[0040] The evaluation circuit 150 is to be Fig. 1 is designed to provide the evaluation signal 195 using a voltage potential present at the tapping point between the first diode terminal 132 and the second energy source terminal 144.

[0041] Thus, Fig. 2, like the Fig. 1 shown monitoring device is adjusted when the battery switch 105 is in the negative pole connection.

[0042] In the embodiment from Fig. 1, the reference potential of the monitoring device is always the positive pole of the intermediate circuit 120, in Fig. 2, the negative pole of the battery 110 is the reference potential of the monitoring device 100.

[0043] Fig. 3 shows a circuit diagram of an embodiment of a monitoring device 100. The monitoring device 100 is similar to the monitoring device 100 of Fig. 1, except that the energy source 140 is designed as a voltage source.

[0044] The first pole 102 of the battery 110 and the first pole 104 of the intermediate circuit 120 are each designed as a positive pole.

[0045] According to one embodiment, the energy source 140 has a first resistor 300, a second resistor 305, and a supply voltage potential 310, which can also be referred to as Vcc. The first resistor 300, which can also be referred to as R1, is connected, for example, between the supply voltage potential 310 and the second energy source terminal 144 of the energy source 140. The second resistor, which can also be referred to as R2, is connected between the first energy source terminal 142 and the second energy source terminal 144 of the energy source 140. The first resistor 300 and the second resistor 305 form a voltage divider.

[0046] In other words, in Fig. 3, instead of the current source iDESAT, a voltage source with a high-resistance voltage divider is used. When the battery switch 105 is closed, the voltage drop, which can also be referred to as Vcc, occurs at the first resistor 300, and no voltage is present at the input 152 of the comparator 158. When the switch is open, the voltage divider is formed by the first resistor 300 and the second resistor 305, so that a voltage adjustable via the resistor divider is produced at the input 152 of the comparator 158.

[0047] Fig. 4 shows a circuit diagram of an embodiment of a monitoring device 100. The monitoring device 100 is similar to the monitoring device 100 of Fig. 1, except that the series circuit 135 includes a third resistor 400.

[0048] The first pole 102 of the battery 110 and the first pole 104 of the intermediate circuit 120 are each designed as a positive pole.

[0049] For example, the diode 130 is connected between the third resistor 400 and the energy source 140.

[0050] As soon as the battery 110 is decoupled from the intermediate circuit 120, no recuperation occurs or energy input from the electric machine to the intermediate circuit is technically prevented, since otherwise the recuperated energy from the rotation of the electric machine would overcharge the intermediate circuit 120. However, a slight overcharge of the intermediate circuit 120 compared to the battery 110 may be permissible. If it is expected that the intermediate circuit voltage will rise above the battery voltage during operation, which can also occur during recuperation without the battery being decoupled, the third resistor 400, which can also be referred to as high-ohmic resistor R3, is added. The current strength of the current source iDESAT, the reference voltage connection 180, which can also be referred to as uRef, and the resistance value R3 of the third resistor 400 are coordinated to ensure safe operation of the monitoring device 100.

[0051] The Fig. The embodiments described in Figures 1 to 4 can be combined. For example, replacing the Fig. 1, Fig. 2 and Fig. 4 shown current source iDESAT by the voltage source Vcc with the first resistor and the second resistor from Fig. 3 in connection with the connection in the negative pole connection between battery 110 and intermediate circuit 120 in Fig. 2 feasible.

[0052] Fig. 5 shows a schematic representation of an embodiment of a motor vehicle 500.

[0053] The motor vehicle 500 has an electric axle drive 510 with an electric machine 505. Electrical energy for operating the electric machine 505 is provided by a power supply device, for example, the battery 110. For example, a direct current is provided by the battery 110, which is converted into an alternating current, for example, a three-phase alternating current, using a converter device 175 and supplied to the electric machine 505. A shaft driven by the electric machine 505 is coupled directly or using a transmission device 506 to at least one wheel 508 of the motor vehicle 500. Thus, the motor vehicle 500 can be propelled using the electric machine 505.According to one embodiment, the electric axle drive 510 comprises a housing in which the converter device 175, the electric machine 505 and the transmission device 506 are arranged in an integrated manner.

[0054] The converter device 175 includes the converter unit 185 for converting the battery voltage into a drive voltage, as well as the battery switch 105. The battery switch 105 is connected to the converter unit 185 via an intermediate circuit. The battery switch 105 connects the battery 110 to the intermediate circuit of the converter unit 185.

[0055] Fig.6 shows a flowchart of an embodiment of a method 600 for monitoring a closed state of a battery switch. The battery switch is, for example, a battery switch from one of the figures described above. The method 600 comprises a generating step 605 and a providing step 610. In generating step 605, a current flow or a voltage is generated between the first switch terminal of the battery switch and the second switch terminal of the battery switch.

[0056] The generating step 605 is performed using the energy source.

[0057] In step 610 of providing, an evaluation signal is provided that indicates the closed state of the battery switch. Step 610 of providing is performed using the evaluation circuit and a voltage potential applied to the first diode terminal. Reference symbol 100 monitoring device 102 first pole of the battery 104 first pole of the intermediate circuit 105 Battery switch 106 first switch connection of the battery switch 108 second switch connection of the battery switch 110 Battery 120 intermediate circuit 130 diodes 132 first diode connection 134 second diode connection 135 series connection 140 Energy source 142 first energy source connection 144 second energy source connection 150 evaluation circuit 152 first entrance 154 second entrance 156 Exit 158 Comparator 160 Ground potential connection 175 Converter device 180 Reference voltage connection 185 Converter device 190 Flow direction 195 Evaluation signal 202 second pole of the battery 204 second pole of the intermediate circuit 300 first resistance 305 second resistance 310 Supply voltage potential 400 third resistance 500 motor vehicles 505 electric machine 506 Gearbox device 508 bike 510 electric axle drive 600 Method for monitoring a closing state of a battery switch 605 Generation step 610 Step of deployment

Claims

[1] Monitoring device (100) for monitoring a closed state of a battery switch (105), wherein the battery switch (105) has a first switch terminal (106) for connecting the battery switch (105) to a pole (102; 202) of a battery (110) and a second switch terminal (108) for connecting the battery switch (105) to a pole (104; 204) of an intermediate circuit (120), wherein the monitoring device (100) has the following features: a series circuit (135) comprising a power source (140) and a diode (130), the series circuit (135) being connected in parallel to the battery switch (105); the energy source (140) having a first energy source terminal (142) and a second energy source terminal (144), wherein the energy source (140) is configured to generate a current flow or a voltage between the first switch terminal (106) of the battery switch (105) and the second switch terminal (108) of the battery switch (105); the diode (130) having a first diode terminal (132) and a second diode terminal (134), wherein the first diode terminal (132) is connected to the second power source terminal (144); and an evaluation circuit (150) which is designed to provide an evaluation signal (195) which indicates the closed state of the battery switch (105) using a voltage potential applied to the first diode terminal (132). [2] The monitoring device (100) of claim 1, wherein the diode (130) has a cathode and an anode, the first diode terminal (132) being the anode and the second diode terminal (134) being the cathode. [3] Monitoring device (100) according to one of the preceding claims, wherein the evaluation circuit (150) comprises a comparator (158), wherein the comparator (158) has a first input (152), a second input (154) and an output (156), wherein the comparator (158) is connected via the first input (152) to the first diode terminal (132) and is connected via the second input (154) to a reference voltage terminal (180), wherein the comparator (158) provides the evaluation signal (195) at the output (156). [4] Monitoring device (100) according to one of the preceding claims, wherein the first power source terminal (142) is connected to the second switch terminal (108) and wherein the second diode terminal (134) is connected to the first switch terminal (106). [5] Monitoring device (100) according to one of claims 1 to 3, wherein the first power source terminal (142) is connected to the first switch terminal (106) and wherein the second diode terminal (134) is connected to the second switch terminal (108). [6] Monitoring device (100) according to one of the preceding claims, wherein the energy source (140) is designed as a current source. [7] Monitoring device (100) according to one of claims 1 to 5, wherein the energy source (140) is designed as a voltage source. [8] Monitoring device (100) according to one of the preceding claims, wherein the energy source (140) comprises a first resistor (300), a second resistor (305) and a supply voltage potential (310), wherein the first resistor (300) is connected between the supply voltage potential (310) and the second energy source terminal (144) of the energy source (140), and wherein the second resistor (305) is connected between the first energy source terminal (142) and the second energy source terminal (144) of the energy source (140). [9] Monitoring device (100) according to one of the preceding claims, wherein the series circuit (135) comprises a third resistor (400). [10] Monitoring device (100) according to claim 9, wherein the diode (130) is connected between the third resistor (400) and the power source (140). [11] Monitoring device (100) according to one of the preceding claims, with the battery switch (105) having the first switch terminal (106) for connecting the battery switch (105) to the pole (102; 204) of the battery (110) and the second switch terminal (108) for connecting the battery switch (105) to the pole (104; 204) of the intermediate circuit (120). [12] Converter device (175) with the monitoring device (100) according to claim 11, with an intermediate circuit (120) and with a converter device (185) for converting a battery voltage into a drive voltage, wherein the intermediate circuit (120) is connected between the battery switch (105) and the converter device (185). [13] Electric axle drive (510) for a motor vehicle (500) with at least one electric machine (505), a transmission device (506) and a converter device (100), characterized bythat the converter device (100) is designed according to claim 12. [14] Motor vehicle (500) comprising an electric axle drive (510) according to claim 13 and / or a converter device (100) according to claim 12. [15] Method (600) for monitoring a closed state of a battery switch (105), wherein the battery switch (105) has a first switch terminal (106) for connecting the battery switch (105) to a pole (102; 202) of a battery (110) and a second switch terminal (108) for connecting the battery switch (105) to a pole (104;204) of an intermediate circuit (120), wherein the method (600) is carried out using a series circuit (135) which has an energy source (140) and a diode (130) and using an evaluation circuit (150), wherein the series circuit (135) is connected in parallel to the battery switch (105), wherein the energy source (140) has a first energy source terminal (142) and a second energy source terminal (144), wherein the diode (130) has a first diode terminal (132) and a second diode terminal (134), wherein the first diode terminal (132) is connected to the second energy source terminal (144), and wherein the method (600) comprises the following steps:; Generating (605) a current flow or a voltage between the first switch terminal (106) of the battery switch (105) and the second switch terminal (108) of the battery switch (105) using the energy source (140); and Providing (610) an evaluation signal (195) indicating the closed state of the battery switch (105) using the evaluation circuit (150) and a voltage potential applied to the first diode terminal (132).

Images