Method for the safe operation of a high-voltage electrical system of a motor vehicle, testing unit and high-voltage electrical system

Abstract

Method for the safe operation of a high-voltage electrical system (2) of a motor vehicle (1) comprising the following steps: - Applying a low-voltage test voltage (10) to the high-voltage electrical system (2); - Determining a voltage value (12) of the low-voltage test voltage (10) received by at least one high-voltage consumer (3, 4, 5) of the high-voltage on-board network (2); - Transmitting the voltage value (12) to a monitoring unit (6) of the high-voltage electrical system (2); - Checking the voltage value (12) by the verification unit (6); and - Applying a high voltage (13) to the high-voltage electrical system (2) if the checked voltage value (12) is within a tolerance range.

Description

[0001] The invention relates to a method for safely operating a high-voltage electrical system of a motor vehicle. Furthermore, the invention relates to a testing unit for a high-voltage electrical system of a motor vehicle. The invention also relates to a high-voltage electrical system with a corresponding testing unit.

[0002] Methods for the safe operation of high-voltage on-board electrical systems in motor vehicles are known. For example, a high-voltage consumer in a high-voltage on-board electrical system usually has a high-voltage interlock (HV interlock). The high-voltage interlock monitors the correct connection of plug connections in the high-voltage circuit with the goal of preventing electrical hazards caused by unintentional, improper, or otherwise unplugging a high-voltage plug connection. To achieve this goal, the high-voltage on-board electrical system usually has a so-called pilot line or safety line. This is usually a series circuit supplied with 12 V on-board voltage that runs from high-voltage plug connection to high-voltage plug connection. If the pilot line circuit is interrupted, for example by unplugging one of the plug connections and the resulting disconnection of the pilot contacts, this is detected by a high-voltage control unit.As a result, the high-voltage control unit typically immediately opens a high-voltage main relay and de-energizes the high-voltage electrical system. The pilot contacts or safety contacts are typically located in all relevant plug contacts and protective covers of the high-voltage electrical system. Document DE 10 2010 056 235 A1 describes a test in which a test voltage is measured at a load and whether the test voltage is also detected at the load. Document US 2013 / 0293237 A1 describes the use of a low-voltage voltage to measure insulation resistance.

[0003] The disadvantage is that the well-known high-voltage locking system requires the pilot line, i.e. a cable, to be routed through the entire vehicle.

[0004] It is an object of the present invention to provide a method, a testing unit and a high-voltage electrical system in which or with which a high-voltage electrical system of a motor vehicle can be designed more simply.

[0005] This object is achieved by a method, a checking unit and a high-voltage electrical system according to the independent claims.

[0006] A method according to the invention ensures the safe operation of a motor vehicle's high-voltage electrical system. The following steps are performed: - Applying a low-voltage test voltage, in particular a constant one, to the high-voltage vehicle electrical system; - Determining a voltage value of the low-voltage test voltage by at least one high-voltage consumer of the high-voltage vehicle electrical system; - Transmitting the voltage value to a testing unit of the high-voltage vehicle electrical system; - Checking the voltage value by the verification unit; and - Applying a high voltage to the high-voltage vehicle electrical system if the checked voltage value is within a tolerance range.

[0007] The invention is based on the finding that the high-voltage electrical system can also be operated without the pilot line or safety line if the high-voltage electrical system is first subjected to the low-voltage test voltage for testing purposes. This allows for a simpler design of the high-voltage electrical system.

[0008] Furthermore, material and installation space can be saved. For example, a high-voltage connector without the safety line can be made smaller, thus saving installation space.

[0009] High voltage (HV) is defined as a voltage of 60 V or greater. Low voltage is defined as a voltage below 60 V.

[0010] After the low-voltage test voltage is applied to the high-voltage vehicle electrical system, the low-voltage test voltage is initially kept constant. The low-voltage test voltage is preferably greater than 12 V but less than 60 V. In particular, the low-voltage test voltage is between 40 V and 50 V. Preferably, the low-voltage test voltage is below 60 V to such an extent that the low-voltage test voltage itself, within a tolerance specified by the tolerance range, is not or will not exceed 60 V. A low-voltage test voltage greater than 12 V is advantageous because resistances in the high-voltage vehicle electrical system can be taken into account more effectively.

[0011] The high-voltage consumer can be implemented as a diverse component of the high-voltage electrical system. For example, the high-voltage consumer can be an electric traction unit, an inverter, a DC-DC converter, a heating unit, an air conditioning compressor, or a high-voltage battery.

[0012] When the high-voltage vehicle electrical system is subjected to the low-voltage test voltage, the high-voltage battery is, in particular, disconnected from the high-voltage vehicle electrical system, for example, by a switch. The high-voltage vehicle electrical system is then subjected to the high-voltage voltage, for example, by electrically connecting or switching on the high-voltage battery to the high-voltage vehicle electrical system. The high-voltage voltage is, for example, 400 V or 800 V. Even if the switch, in particular a contactor, of the high-voltage battery is open and the high-voltage vehicle electrical system is not subjected to the high-voltage voltage, the high-voltage battery is preferably connected to the high-voltage vehicle electrical system so that this connection or connection can be tested with the low-voltage test voltage.

[0013] When the voltage value is checked by the checking unit, it is determined, firstly, whether the voltage value has been transmitted. This means that the checking unit knows which high-voltage consumers are located in the high-voltage electrical system and how many different voltage values ​​must therefore be received before the high-voltage electrical system can be supplied with the high-voltage voltage. Secondly, when checking the voltage value, it is determined whether the voltage value is within the tolerance range. If the voltage value is outside the tolerance range, the high-voltage electrical system is not supplied with the high-voltage voltage. In this case, the connection of the high-voltage voltage is prevented, particularly by the checking unit.It may then be the case, for example, that the high-voltage electrical system continues to be subjected to the low-voltage test voltage in order to carry out further measurements, or an error is output and the high-voltage electrical system is de-energized.

[0014] In particular, it is intended that a voltage value is determined for each of the high-voltage consumers in the high-voltage electrical system, and all of the determined voltage values ​​are sent to the verification unit. In particular, the high-voltage electrical system is only applied with the high-voltage voltage if all voltage values ​​of all high-voltage consumers in the high-voltage electrical system are within the tolerance range.

[0015] However, it can also be provided that the high-voltage consumers of the high-voltage electrical system are configured differently. For example, some of the high-voltage consumers can be configured without safety lines, determine the voltage value, and transmit it to the verification unit, while others are configured with a known safety line. The high-voltage electrical system is then only supplied with high-voltage voltage if all voltage values ​​from all high-voltage consumers in the high-voltage electrical system without safety lines are within the tolerance range and all safety line signals from all other high-voltage consumers with a safety line are valid.

[0016] The tolerance value range can, for example, be set around a certain low-voltage test value or can be set by specifying that the deviations or a deviation may only deviate by a certain value + / - from an average value of all voltage values, for example an arithmetic mean or a median.

[0017] Preferably, the high-voltage electrical system is supplied with the low-voltage test voltage by a DC / DC converter, to which the high-voltage electrical system and a low-voltage electrical system of the motor vehicle are electrically connected. The low-voltage electrical system preferably has a low-voltage battery, in particular a 12 V battery, which provides the energy for charging a resonant circuit of the DC / DC converter in order to be able to supply the high-voltage electrical system with the low-voltage test voltage. Using the DC / DC converter of the low-voltage electrical system, the high-voltage electrical system can be supplied with the low-voltage test voltage without the need for an additional battery to be connected to the high-voltage electrical system.

[0018] Furthermore, it is preferably provided that a low-voltage voltage of the low-voltage vehicle electrical system, in particular 12 V, is converted by the DC-DC converter to the low-voltage test voltage. It is therefore preferably provided that the low-voltage voltage is not simply supplied to the high-voltage vehicle electrical system as a low-voltage test voltage without adjustment, but rather the low-voltage voltage is increased, in particular to a voltage between 40 V and 50 V, in order to be able to be determined or measured more reliably in the high-voltage vehicle electrical system.

[0019] Furthermore, it is preferably provided that a safety warning is issued in the motor vehicle if the checked voltage value is outside the tolerance range. The safety warning can be issued, for example, visually and / or haptically and / or acoustically in the motor vehicle.

[0020] Furthermore, it is preferably provided that a log file of the motor vehicle is generated that can be viewed by a workshop if the checked voltage value is outside the tolerance range. The log file is then generated specifically if the checked voltage value is outside the tolerance range, for example, or an existing log file is supplemented with an entry. The log file preferably also indicates which device or high-voltage consumer of the high-voltage vehicle electrical system did not transmit a voltage value or determined a voltage value that is outside the tolerance range. This makes it easier for the workshop to locate a potentially defective high-voltage consumer.

[0021] Furthermore, it is preferably provided that, at, in particular, predetermined time intervals, a further voltage value of the applied high-voltage is determined by the at least one high-voltage consumer, and the further voltage value is transmitted to the checking unit if the high-voltage vehicle electrical system is supplied with the high-voltage voltage. Preferably, the further voltage value is then checked by the checking unit, and the supply of the high-voltage voltage to the high-voltage vehicle electrical system is continued if the checked further voltage value is within a further tolerance value range. The further tolerance value range is preferably designed to be larger than the tolerance value range. For example, the further tolerance value range can range from + / - 20 V or even 40 V with respect to a predetermined test value.The additional voltage value means that the high-voltage electrical system can be continuously checked during operation to ensure that the connection between the individual high-voltage consumers is secure.

[0022] The invention also relates to a testing unit for a high-voltage electrical system of a motor vehicle. The testing unit is configured to test a voltage value of a low-voltage test voltage received from a high-voltage consumer and to generate a control signal for applying a high-voltage voltage if the voltage value is assigned to a tolerance range during the testing.

[0023] The control signal then controls and closes a switch for connecting a high-voltage battery. The high-voltage battery then supplies the high-voltage electrical system with high voltage.

[0024] Preferably, the checking unit is arranged in the high-voltage consumer. For example, one of the high-voltage consumers in the high-voltage electrical system can be configured to provide the checking unit in addition to its primary function. For example, the checking unit can be arranged in the same housing as the high-voltage consumer. The checking unit can also be present in the high-voltage consumer, for example, through a program or software. For example, the checking unit can at least partially utilize a processor, logic, or memory of the high-voltage consumer.

[0025] However, it can also be provided that the testing unit is designed separately from the high-voltage consumer. For example, the testing unit can have no additional functions and, for example, have its own processor and / or logic and / or memory. This can create a testing unit that is particularly fail-safe and robust.

[0026] The invention further relates to a high-voltage vehicle electrical system with a testing unit according to the invention. An important concept here is that at least one high-voltage consumer of the high-voltage vehicle electrical system, in particular all high-voltage consumers of the high-voltage vehicle electrical system, is designed without a safety line. The high-voltage consumer therefore preferably has no connection for a safety line. Preferably, no safety line is carried in the high-voltage cables of the high-voltage vehicle electrical system either. The high-voltage consumer also includes, in particular, a high-voltage battery, which can serve not only as a consumer but also as an energy source. In particular, the high-voltage consumer includes all components of the high-voltage vehicle electrical system that typically have a connection with a safety line in known high-voltage vehicle electrical systems.

[0027] Advantageous embodiments of the method according to the invention are to be regarded as advantageous embodiments of the testing unit and the high-voltage electrical system. The respective components of the testing unit and the high-voltage electrical system are each designed to carry out the respective method steps.

[0028] Further features of the invention emerge from the claims, the figure and the description of the figures.

[0029] Embodiments of the invention are explained in more detail below with reference to a schematic drawing.

[0030] The figure shows a schematic plan view of a motor vehicle with an embodiment of the high-voltage electrical system according to the invention, which has a checking unit and several high-voltage consumers designed without safety lines.

[0031] In the figure, identical or functionally identical elements are given the same reference symbols.

[0032] The figure shows a motor vehicle 1 in a schematic top view. The motor vehicle 1 has a high-voltage electrical system 2. The high-voltage electrical system 2 is designed, for example, for a nominal voltage of 400 V or 800 V.

[0033] The high-voltage electrical system 2 comprises an electric drive unit 3, an electric heating unit 4, and a high-voltage battery 5 as high-voltage consumers. The electric drive unit 3 is preferably designed as the main drive unit of the motor vehicle 1. The electric drive unit 3 is, for example, an electric motor. The electric heating unit 4 is designed, for example, as a PTC heater (PTC - Positive Temperature Coefficient). The high-voltage battery 5 is designed, in particular, as a rechargeable accumulator.

[0034] The high-voltage electrical system 2 also has a checking unit 6. The checking unit 6 can, for example, be integrated into one of the high-voltage consumers 3, 4, 5 or can be designed separately. The checking unit 6 can also be distributed at different locations. The checking unit 6 preferably comprises logic for comparing voltage values. Furthermore, the checking unit 6 preferably comprises a receiving module for receiving voltage values ​​from high-voltage consumers 3, 4, 5. The checking unit 6 preferably also comprises a signal generator module, which transmits a signal to the high-voltage battery 5 or to a switch of the high-voltage battery 5 in order to close or open the switch that electrically connects the high-voltage battery 5 to the high-voltage battery 2. The high-voltage electrical system 2 also has a DC-DC converter 7.The DC-DC converter 7 connects the high-voltage electrical system 2 to a low-voltage electrical system 8 of the motor vehicle 1. According to the exemplary embodiment, the low-voltage electrical system 8 has a low-voltage battery 9. According to the exemplary embodiment, the low-voltage electrical system 8 is designed for a nominal voltage of 12 V, and the low-voltage battery 9 is designed to provide a voltage or a nominal voltage of 12 V.

[0035] When the motor vehicle 1 is started, the high-voltage electrical system 2 is supplied with a constant low-voltage test voltage 10 according to the exemplary embodiment. The low-voltage test voltage 10 is provided by the DC-DC converter 7 according to the exemplary embodiment. The DC-DC converter 7 uses the energy from the low-voltage battery 9 and increases a low-voltage voltage 11 to the low-voltage test voltage 10. In particular, an oscillating circuit of the DC-DC converter 7 is precharged to the low-voltage test voltage 10 by the low-voltage battery 9.

[0036] After the high-voltage electrical system 2 is supplied with the low-voltage test voltage 10 and the low-voltage test voltage 10 is kept constant, a respective voltage value 12 of the respectively applied low-voltage test voltage 10 is determined for each high-voltage consumer 3, 4, 5. The respectively determined voltage value 12 is transmitted by the respective high-voltage consumer 3, 4, 5 to the checking unit 6. The checking unit 6 checks the respectively received voltage values ​​12 and, by doing so, determines whether the voltage values ​​12 lie within a tolerance range. The tolerance range can, for example, be predetermined or can be specified anew each time by an average value, for example an arithmetic mean or a median.When checking the respective voltage values ​​12, the checking unit 6 also checks whether the respective voltage value 12 was transmitted by all high-voltage consumers 3, 4, 5 in the high-voltage vehicle electrical system 2.

[0037] If the respective voltage value 12 has been transmitted from all high-voltage consumers 3, 4, 5 to the checking unit 6 and the respective voltage values ​​12 are within the tolerance range, the high-voltage electrical system 2 is supplied with a high-voltage voltage 13. The high-voltage voltage 13 is present, for example, as 400 V or 800 V. The high-voltage voltage 13 is at least 60 V. According to the exemplary embodiment, the high-voltage voltage 13 is applied to the high-voltage electrical system 2 by closing a contactor or a switch using a control signal 14 from the checking unit 6.

[0038] If, when checking the voltage values ​​12, it is determined that the respective voltage value 12 was not received by all high-voltage consumers 3, 4, 5, or that the respective voltage value 12 lies outside the tolerance range, a log file 15 is generated by the checking unit 6 according to the exemplary embodiment. Furthermore, a safety warning 16 is issued by the motor vehicle 1.

[0039] If the high-voltage electrical system 2 is only supplied with the high-voltage voltage 13 and the motor vehicle 1 is operated as intended, for example, a further voltage value of the applied high-voltage voltage 13 is determined at predetermined intervals, and the further voltage value is transmitted to the checking unit 6. The checking unit 6 then checks whether the respective further voltage value lies within a further tolerance range. If this is the case, the high-voltage electrical system 2 continues to be supplied with the high-voltage voltage 11. If this is not the case, the supply of the high-voltage voltage 11 is interrupted or the high-voltage electrical system 2 is de-energized. List of reference symbols 1 motor vehicle 2 High-voltage electrical system 3 electric drive unit 4 electric heating units 5 high-voltage batteries 6 Verification unit 7 DC-DC converters 8 Low-voltage electrical system 9 Low-voltage battery 10 Low-voltage test voltage 11 Low voltage 12 Voltage value 13 High voltage 14 Control signal 15 Log file 16 Security warning

Claims

[1] Method for the safe operation of a high-voltage electrical system (2) of a motor vehicle (1), in which the following steps are carried out: - applying a low-voltage test voltage (10) to the high-voltage vehicle electrical system (2); - determining a voltage value (12) of the low-voltage test voltage (10) received by at least one high-voltage consumer (3, 4, 5) of the high-voltage vehicle electrical system (2); - transmitting the voltage value (12) to a checking unit (6) of the high-voltage vehicle electrical system (2); - checking the voltage value (12) by the checking unit (6); and - Applying a high-voltage voltage (13) to the high-voltage vehicle electrical system (2) if the checked voltage value (12) is within a tolerance value range. [2] Method according to claim 1, characterized bythat the high-voltage on-board network (2) is supplied with the low-voltage test voltage (10) by a DC-DC converter (7), with which the high-voltage on-board network (2) and a low-voltage on-board network (8) of the motor vehicle (1) are electrically connected. [3] Method according to claim 2, characterized by that a low-voltage voltage (11) of the low-voltage vehicle electrical system (8) is converted by the DC-DC converter (7) to the low-voltage test voltage (10). [4] Method according to one of the preceding claims, characterized by that a safety warning (16) is issued in the motor vehicle (1) if the checked voltage value (12) is outside the tolerance value range. [5] Method according to one of the preceding claims, characterized by that a log file (15) of the motor vehicle (1) that can be viewed by a workshop is generated if the checked voltage value (12) is outside the tolerance value range. [6] Method according to one of the preceding claims, characterized by that at intervals a further voltage value of the applied high-voltage voltage (13) is determined by the at least one high-voltage consumer (3, 4, 5) and the further voltage value is transmitted to the checking unit (6) if the high-voltage vehicle electrical system (2) is supplied with the high-voltage voltage (13). [7] Testing unit (6) for a high-voltage on-board network (2) of a motor vehicle (1), which is designed to test a voltage value (12) of a low-voltage test voltage (10) received from a high-voltage consumer (3, 4, 5) and to generate a control signal (14) for applying a high-voltage voltage (13) if the voltage value (12) lies within a tolerance value range during the test. [8] Verification unit (6) according to claim 7, characterized by that the checking unit (6) is arranged in the high-voltage consumer (3, 4, 5). [9] Verification unit (6) according to claim 7, characterized by that the checking unit (6) is designed separately from the high-consumer (3, 4, 5). [10] High-voltage vehicle electrical system (2) with a checking unit (6) according to one of claims 7 to 9, wherein at least one high-voltage consumer (3, 4, 5) of the high-voltage vehicle electrical system (2) is designed without safety lines.

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