Method for performing a dielectric strength test of a high-voltage battery

Abstract

Method for performing a dielectric strength test of a high-voltage battery (50), in particular of an electrically operated vehicle, with a device (100) comprising a first DC voltage connection (10) and a second DC voltage connection (12) for electrical connection to an intermediate circuit (40) and / or an internal circuit (52) of the high-voltage battery (50), and a ground connection (14) for electrical connection to a ground potential (GND) of the high-voltage battery (50), wherein the ground connection (14) has a first switching element (16) for establishing and / or disconnecting the electrical contact to an electrical ground potential (32) of the device (100), at least comprising Electrical connection of the high-voltage battery (50) to the first and second DC voltage terminals (10, 12), as well as the ground terminal (14); Closing of contactors (54, 56) of the high-voltage battery (50); Measuring a voltage between the first and second DC voltage terminals (10, 12); and Measuring a voltage between the intermediate circuit (40) and the electrical ground potential (32) of the device (100), characterized by the fact that the first switching element (16) is opened when no voltage can be measured between the intermediate circuit (40) and the electrical ground potential (32); and / or the high-voltage battery (50) is electrically connected to a control terminal (18) of a control line (20) of the device (100) for controlling the contactors (54, 56) of the high-voltage battery (50), wherein an electrical contact between the intermediate circuit (40) and the internal circuit (52) of the high-voltage battery (50) can be established and / or disconnected by means of the control line (20), and wherein in the event of a fault the contactors (54, 56) of the high-voltage battery (50) are opened by means of a second switching element (22) of the control terminal (18) of the control line (20).

Description

[0001] The invention relates to a method for carrying out a dielectric strength test of a high-voltage battery and in particular for controlling and / or monitoring the high-voltage battery during the carrying out of a dielectric strength test according to the preamble of claim 1.

[0002] Devices and methods for testing and controlling electronic components are known.

[0003] DE 10 2014 215 260 A1 discloses, for example, a method for testing the function of a switching device, in particular a battery system, wherein the switching device is actuated by applying an electrical voltage or an electrical current. It is provided that the switching device is excited to oscillate by a voltage or current signal, and that a voltage or current waveform of the switching device is monitored in order to detect a response signal generated by the excited switching device, whereby the functionality of the switching device is inferred depending on the response signal.

[0004] German patent application DE 10 2018 206 337 B4 describes a test device used for testing a switching device for a vehicle's high-voltage battery. The test device comprises a voltage source for generating an electrical test voltage between a positive high-voltage path and a negative high-voltage path of the switching device. Furthermore, the test device includes a first connection device and a first current source for supplying a first electrical test current into the positive high-voltage path, wherein, during testing of the switching device, the first connection device, the first current source, and the positive high-voltage path together form a first circuit.Furthermore, the test device includes a second connection device and a second power source for supplying a second electrical test current into the negative high-voltage path, wherein, when testing the switching device, the second connection device, the second power source and the negative high-voltage path together form a second circuit.

[0005] German patent application DE 10 2018 112 766 A1 discloses a controller configured to control a power electronics circuit. The controller includes a high-voltage pin, a power supply pin, a startup circuit configured to conduct electricity from the high-voltage pin to the power supply pin, and a comparator circuit configured to determine whether the voltage level of the high-voltage pin exceeds a turn-on voltage threshold. The comparator circuit is further configured to cause the controller to enter normal operating mode in response to the determination that the voltage level of the high-voltage pin exceeds the turn-on voltage threshold. The controller also includes a level detection circuit configured to determine the turn-on voltage threshold based on a level of the high-voltage pin.

[0006] From DE 10 2014 220 017 A1 a battery system is known comprising a battery designed to supply a high-voltage network with electrical energy and a measuring device for measuring at least one insulation resistance present between the battery and a housing of the battery.

[0007] From DE 10 2013 217 458 A1 a contactor assembly for a high-voltage storage unit comprising electrochemical cells is known.

[0008] A test bench for high-voltage batteries is known from EP 2 637 028 A1.

[0009] One object of the invention is to provide a robust method for carrying out a dielectric strength test of a high-voltage battery, in particular of an electrically operated vehicle.

[0010] The aforementioned problem is solved using the features of an independent claim.

[0011] Favorable embodiments and advantages of the invention will become apparent from the further claims, the description and the drawing.

[0012] A device for performing a dielectric strength test of a high-voltage battery, in particular of an electrically powered vehicle, comprises at least a first DC voltage terminal and a second DC voltage terminal for electrical connection to an intermediate circuit and / or an internal circuit of the high-voltage battery, and a ground terminal for electrical connection to a ground potential of the high-voltage battery. The ground terminal may include a first switching element for establishing and / or disconnecting the electrical contact to an electrical ground potential of the device.

[0013] In particular, the device is designed and / or suitable for controlling and / or monitoring the high-voltage battery during the performance of a dielectric strength test.

[0014] During the manufacture of electrical products, a dielectric strength test can be performed to ensure the quality of the product and its insulation. Specifically, this test verifies that no insulation gaps have been reduced and that the product is in good working order. For this purpose, especially with high-voltage batteries, the switching elements must be closed. The test requires disabling the internal insulation monitoring and galvanically isolating the component from its environment.

[0015] The device enables autonomous control and / or monitoring of the high-voltage battery during dielectric strength testing. No additional interface is required to communicate with the battery's control components or environmental monitoring system to determine the battery's status under test. This eliminates the need for implementation and maintenance of the device.

[0016] To perform the voltage withstand test, the HV battery is connected to the intermediate circuit and the device by closing the battery contactors.

[0017] This device can be used to advantageously monitor the status of the high-voltage battery's contactors. To detect closed contactors, the device monitors various parameters. One such parameter is the so-called link voltage. When the contactors are closed, the link voltage rises to the value of the battery pack. This value is precisely defined for battery testing and must be within a range of 0% SOC to 100% SOC.

[0018] Optionally, the control current of the contactors can be monitored. This control current must correspond to the value required to control closed contactors. Contactors have a characteristic control current profile, which can also be monitored. If clear switching sequences are defined, these can also be monitored. This is possible if the control voltage line is routed through the device and the current value can be measured.

[0019] With internal insulation monitoring of the high-voltage battery, the system monitors for the deactivation of the insulation monitoring. The battery's insulation is monitored cyclically. For this purpose, a test voltage is applied between a high-voltage potential and ground. This test voltage can also be measured externally. The proposed device continuously measures the voltage between the relevant high-voltage potential and ground. If no voltage value can be determined for the duration of an insulation monitoring cycle, it can be concluded that the insulation monitoring is deactivated.

[0020] To ensure galvanic isolation of the test object, the device must be able to control this isolation. Since opening electrical components typically requires consideration of ESD (electrostatic discharge) requirements, the device incorporates a first switching element that is normally closed when de-energized. For the dielectric strength test, the device energizes this first switching element, thus disconnecting the ground connection.

[0021] To guarantee a safe system state in the event of a fault, an optional function can be provided that disconnects the supply voltage to the contactors of the device under test, i.e., the high-voltage battery. This allows a voltage-free, safe state to be established after the intermediate circuit is discharged.

[0022] Advantageously, the device can be used flexibly with existing high-voltage batteries and represents a robust solution compared to otherwise necessary system adjustments such as software changes to the test system and the test object.

[0023] According to an advantageous embodiment, the device can further include a control connection for a control line for controlling contactors of the high-voltage battery, by means of which an electrical contact between the intermediate circuit and the internal circuit of the high-voltage battery can be established and / or disconnected. In this way, both the state of the contactors, whether open or closed, and the function of the contactors themselves can be advantageously monitored. In addition, the contactors can be opened by the device in the event of a fault.

[0024] According to an advantageous embodiment of the device, the control connection of the control line can have a second switching element. This allows the contactors of the high-voltage battery to be flexibly controlled via the device.

[0025] According to an advantageous embodiment of the device, the control line can include a current sensor. Optionally, the control current of the contactors can be monitored. The control current must correspond to the magnitude required to control closed contactors. Contactors have a characteristic control current profile, which can also be monitored.

[0026] According to an advantageous embodiment, the device can further comprise a first voltage measuring device for measuring a voltage between the first and second DC voltage terminals. The link voltage of the battery pack can be determined using the first voltage measuring device.

[0027] According to an advantageous embodiment, the device can further comprise a second voltage measuring device for measuring a voltage between the intermediate circuit and the electrical ground potential. The second voltage measuring device can be used to verify the deactivation of the internal insulation monitoring of the high-voltage battery.

[0028] According to an advantageous embodiment, the device can further include a control unit, in particular a software control unit, for the autonomous execution of the dielectric strength test. This allows the individual steps of the dielectric strength test to be flexibly defined and controlled.

[0029] The aforementioned method for carrying out a dielectric strength test of a high-voltage battery, in particular of an electrically powered vehicle, is carried out using a device mentioned above and comprises at least: Electrically connecting the high-voltage battery to the first and second DC terminals, as well as the ground terminal; closing the contactors of the high-voltage battery; measuring a voltage between the first and second DC terminals; measuring a voltage between an intermediate circuit and the electrical ground potential of the device.

[0030] In particular, the method according to the invention is designed and / or suitable for controlling and / or monitoring the high-voltage battery during the performance of a dielectric strength test.

[0031] During the manufacture of electrical products, a dielectric strength test must be performed to ensure that no insulation distances have been reduced and that the product is in good working order. For this purpose, especially with high-voltage batteries, the switching elements must be closed. The test requires disabling the internal insulation monitoring and galvanically isolating the component from the environment.

[0032] To perform the voltage withstand test, the HV battery is connected to the intermediate circuit and the device by closing the battery contactors.

[0033] The proposed method allows for advantageous monitoring of the high-voltage battery's contactor status. To detect closed contactors, the device monitors various parameters. Specifically, it measures a so-called link voltage. When the contactors are closed, the link voltage rises to the value corresponding to the battery pack's state of charge (SOC). This value is precisely defined for battery testing and must be within a range of 0% SOC to 100% SOC.

[0034] Optionally, the control current of the contactors can be monitored. This control current must correspond to the value required to control closed contactors. Contactors have a characteristic control current profile, which can also be monitored. If clear switching sequences are defined, these can also be monitored. This is possible if the control voltage line is routed through the device and the current value can be measured.

[0035] With internal insulation monitoring of the high-voltage battery, the system monitors when the insulation monitoring is deactivated. The battery's insulation is monitored cyclically. For this purpose, a test voltage is applied between a high-voltage potential and ground. This test voltage can also be measured externally. The device continuously measures the voltage between the affected high-voltage potential and ground. If no voltage value can be determined for the duration of an insulation monitoring cycle, the insulation monitoring is deactivated.

[0036] According to the invention, the method provides that the first switching element is opened when no voltage can be measured between the intermediate circuit and the electrical ground potential. In this state, the dielectric strength test can be carried out.

[0037] To ensure galvanic isolation of the test object, the device controls the galvanic isolation. Since opening electrical components typically requires consideration of ESD (electrostatic discharge) requirements regarding potential electrostatic discharge, the device incorporates a first switching element that is normally closed when de-energized. For the dielectric strength test, the device energizes this first switching element, thus disconnecting the ground connection.

[0038] Alternatively or additionally, the method according to the invention provides that the high-voltage battery is electrically connected to the control connection, wherein in the event of a fault the contactors of the high-voltage battery are opened by means of the second switching element of the control line.

[0039] To guarantee a safe system state in the event of a fault, an optional function can be provided that disconnects the supply voltage to the contactors of the device under test, i.e., the high-voltage battery. This allows a voltage-free, safe state to be established after the intermediate circuit is discharged.

[0040] Further advantages will become apparent from the following description of the drawings. The drawings illustrate an embodiment of the invention. The drawings, the description, and the claims contain numerous features in combination. A person skilled in the art will expediently consider the features individually and combine them into meaningful further combinations.

[0041] This shows: Fig. 1 a system overview of a device for carrying out a dielectric strength test of a high-voltage battery, in particular of an electrically operated vehicle according to an embodiment of the invention; Fig. 2 the device in the initial state for measuring a voltage of the intermediate circuit with open contactors of the high-voltage battery; Fig. 3 the device when measuring the voltage of the intermediate circuit with the contactors of the high-voltage battery closed; and Fig. 4 the device during the performance of the dielectric strength test of the high-voltage battery.

[0042] In the figures, identical or similar components are numbered with the same reference symbols. The figures merely show examples and are not to be understood as limiting.

[0043] Fig. Figure 1 shows a system overview of a device 100 for carrying out a dielectric strength test of a high-voltage battery 50, in particular of an electrically operated vehicle according to an embodiment of the invention.

[0044] The high-voltage battery 50 comprises a battery pack 51 with a positive DC voltage HV+ and a negative DC voltage HV-, which are applied to an internal circuit 52. The internal circuit 52 can be connected to or disconnected from an external intermediate circuit 40 via contactors 54 and 56. Furthermore, the high-voltage battery 50 has a ground potential GND.

[0045] The device 100 comprises at least one first DC voltage terminal 10 and one second DC voltage terminal 12 for electrical connection to the intermediate circuit 40 and / or the internal circuit 52 of the high-voltage battery 50, as well as a ground terminal 14 for electrical connection to the ground potential GND of the high-voltage battery 50. The ground terminal 14 has a first switching element 16 for establishing and / or disconnecting the electrical contact to an electrical ground potential 32 of the device 100. The ground potential GND of the high-voltage battery 50, which is electrically connected to the ground terminal 14 of the device 100, can be disconnected via the first switching element 16.

[0046] A galvanic isolation of the high-voltage battery 50 can be carried out by controlling the first switching element 16 of the device 100.

[0047] The illustrated device 100 further comprises an optional control connection 18 of a control line 20 for controlling the contactors 54, 56 of the high-voltage battery 50. An electrical contact between the intermediate circuit 40 and the internal circuit 52 of the high-voltage battery 50 can be established or broken by means of the control line 20. The control connection 18 of the control line 20 has a second switching element 22 for this purpose. The control line 20 can also include a current sensor 24.

[0048] Optionally, the device 100 can disconnect the control line 20 by means of the second switching element 22 and thus open the contactors 54, 56 of the high-voltage battery 50.

[0049] The current of the control line 20 can optionally be monitored with the current sensor 24.

[0050] The device 100 further comprises a first voltage measuring device 26 for measuring a voltage between the first and second DC voltage terminals 10, 12, and a second voltage measuring device 28 for measuring a voltage between the intermediate circuit 40 and the electrical ground potential 32.

[0051] The device 100 can thus measure the voltage of the intermediate circuit 40 to the ground of the high-voltage battery 50 via the second voltage measuring device 28. The device 100 can also measure the voltage of the intermediate circuit 40 itself via the first voltage measuring device 26.

[0052] Furthermore, the device 100, as shown, can include a control unit 30, in particular a software control unit, by means of which an autonomous sequence of the dielectric strength test can be controlled. No additional interface for communication with control components of the high-voltage battery 50 is required.

[0053] In Fig. Figure 2 shows the device 100 in its initial state for measuring the voltage of the intermediate circuit 40 with open contactors 54, 56 of the high-voltage battery 50.

[0054] To carry out the dielectric strength test, the high-voltage battery 50 is electrically connected to the device 100.

[0055] According to the inventive method, the high-voltage battery 50 is first electrically connected to the first and second DC voltage terminals 10, 12, and the ground terminal 14.

[0056] Furthermore, the high-voltage battery 50 is electrically connected to the control port 18.

[0057] Then, as in Fig. Figure 3 shows the contactors 54, 56 of the high-voltage battery 50 closed.

[0058] In the following step, the link voltage, i.e. the voltage of the intermediate circuit 40, is determined by measuring the voltage between the first and second DC voltage terminals 10, 12 using the first voltage measuring device 26, in order to check that the contactors 54, 56 are closed and the high-voltage battery 50 is correctly connected.

[0059] The plausibility check of the control of the contactors 54, 56 can optionally also be carried out via the current sensor 24 on the control line 20 by measuring the control current of the contactors 54, 56.

[0060] In the following step, the voltage 28 between intermediate circuit 40 and ground connection GND is measured for a sufficiently long period of time to verify that the internal insulation monitoring of the high-voltage battery 50 has been switched off.

[0061] Once it has been verified that contactors 54 and 56 are closed and the insulation monitoring is deactivated, i.e., no voltage can be measured between the intermediate circuit 40 and the electrical ground potential 32, the ground connection GND is opened for the dielectric strength test using a first switching element 16, as shown in Fig. Figure 4 shows that the galvanic isolation of the high-voltage battery 50 has now been achieved. The dielectric strength test can now be carried out.

[0062] In the event of a fault, it is possible to open the contactors 54 and 56 by means of the device 100 by opening the control line 20 with the second switching element 22. This state corresponds to the representation in Fig. 1. Reference symbol list 10 DC connection 12 DC voltage connection 14 Ground connection 16 first switching element 18 Control connection 20 Control line 22 second switching element 24 Current sensor 26 first voltage measuring device 28 second voltage measuring device 30 Control unit 32 Mass potential 40 Intermediate circle 50 high-voltage battery 51 battery pack 52 internal circuit 54 Schütz 56 Schütz 100 Device HV+ positive DC voltage HV – negative DC voltage GND ground potential

Claims

[1] Method for carrying out a dielectric strength test of a high-voltage battery (50), in particular of an electrically operated vehicle, with a device (100) comprising a first DC voltage terminal (10) and a second DC voltage terminal (12) for electrical connection to an intermediate circuit (40) and / or an internal circuit (52) of the high-voltage battery (50), and a ground terminal (14) for electrical connection to a ground potential (GND) of the high-voltage battery (50), wherein the ground terminal (14) comprises a first switching element (16) for establishing and / or disconnecting the electrical contact to an electrical ground potential (32) of the device (100), at least comprising Electrical connection of the high-voltage battery (50) to the first and second DC voltage terminals (10, 12), as well as the ground terminal (14); Closing of contactors (54, 56) of the high-voltage battery (50); Measuring a voltage between the first and second DC voltage terminals (10, 12); and Measuring a voltage between the intermediate circuit (40) and the electrical ground potential (32) of the device (100), characterized by , that the first switching element (16) is opened when no voltage can be measured between the intermediate circuit (40) and the electrical ground potential (32); and / or the high-voltage battery (50) is electrically connected to a control terminal (18) of a control line (20) of the device (100) for controlling the contactors (54, 56) of the high-voltage battery (50), wherein an electrical contact between the intermediate circuit (40) and the internal circuit (52) of the high-voltage battery (50) can be established and / or disconnected by means of the control line (20), and wherein in the event of a fault the contactors (54, 56) of the high-voltage battery (50) are opened by means of a second switching element (22) of the control terminal (18) of the control line (20). [2] Method according to claim 1 wherein the device (100) has a first voltage measuring device (26) for measuring a voltage between the first and second DC voltage terminal (10, 12). [3] Method according to one of the preceding claims, wherein the device (100) comprises a second voltage measuring device (28) for measuring a voltage between the intermediate circuit (40) and the electrical ground potential (32). [4] Method according to one of the preceding claims, wherein the device (100) comprises a control device (30), in particular a software control device, for autonomous execution of the dielectric strength test.

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