Reduction of transient overvoltage in on-board energy network

Abstract

The invention relates to a method for reducing an overvoltage, in particular a transient overvoltage, in a supply voltage-bearing current path (4) of an on-board energy network (2) of a vehicle (1) between a consumer (3) generating the overvoltage and a further component (5), in which method the voltage on the current path (4) is monitored, and when an overvoltage is determined, the voltage on the current path (4) is reduced. A short-circuit line (18), which is disconnected before this, is closed between the monitored current path (4) and the reference potential (GND) until the overvoltage has been reduced or is expected to be reduced. The invention is particularly advantageously applicable to partially or fully autonomous driving vehicles, in particular electric vehicles.

Description

Field of the Invention

[0001] The present invention relates to a method for reducing overvoltages, in particular transient overvoltages, in a current path of an on-vehicle energy network of a vehicle, wherein a voltage on the current path is monitored, and when an overvoltage is determined, a short-circuit line that was previously open between the monitored current path and a reference potential is closed until the overvoltage has been reduced or is expected to be reduced. The present invention also relates to a vehicle having an on-vehicle energy network, which vehicle has at least a current path carrying a supply voltage and a voltage measuring device for measuring the voltage on the current path. The present invention is particularly advantageously applicable to partially or fully autonomous vehicles, in particular electric vehicles. Background Art

[0002] DE102014209267A1 discloses a heating device and a method for reducing overvoltages in a first part of an on-vehicle network of an electrically drivable vehicle. The method includes the steps of: identifying an overvoltage or other information indicating an impending overvoltage event in the first part of the on-vehicle network, and in response thereto, closing an electrical connection between an electric heating device of the vehicle and the first part of the on-vehicle network to reduce the overvoltage.

[0003] DE19742391C1 discloses a method for protecting an electronic control device in a motor vehicle, wherein an overvoltage pulse, in particular a load dump pulse, is detected, and when such an overvoltage pulse occurs, one or more consumers are switched on. Thereby, the overvoltage pulse can be reduced very quickly even before it reaches the maximum value that it would reach without compensation, thereby protecting the electronic circuits and control devices contained in the motor vehicle. This enables overvoltage protection to be achieved without additional components.

[0004] DE10291613T5 discloses a system for eliminating overvoltages in a vehicle's power supply, which system includes: a load absorption device having low resistance and high power absorption characteristics; and a control component that selectively couples the load absorption device to a power supply device when the voltage of the power supply exceeds a preselected threshold. Summary of the Invention

[0005] The object of the present invention is to at least partially overcome the disadvantages of the prior art and, in particular, to provide a particularly simple and cost-effective possibility to reliably reduce transient overvoltages generated by feedback of consumers into the on-vehicle energy network.

[0006] This object is solved by the features of the independent claims. Preferred embodiments can be derived in particular from the dependent claims.

[0007] This task is solved by a method for reducing overvoltages, in particular transient overvoltages, in a current path that carries the supply voltage of the on-vehicle energy network of a vehicle, the current path being between a consumer that generates the overvoltage and another component, wherein,

[0008] - monitoring the voltage on the current path and, when an overvoltage is determined,

[0009] - closing a short-circuit line that was previously open between the monitored current path and the reference potential until the overvoltage has been reduced or is expected to be reduced.

[0010] When the short-circuit line is closed, the overvoltage is advantageously easy to detect and can be reliably reduced by the short-circuit line. In addition, the method can be implemented at low cost. In addition, complex and time-consuming evaluations can be dispensed with, so that the short-circuit current flowing through the short-circuit line can be triggered quickly. In addition, the short-circuit line can advantageously be used at almost any location without or with only minor adaptations to the on-vehicle energy network.

[0011] Transient overvoltages can in particular be generated due to the feedback of electrical energy from the consumer in the current path. This is particularly disadvantageous when another component connected to the consumer via the current path is sensitive to overvoltages, i.e., reacts sensitively to overvoltages, such as by experiencing functional failures, functional malfunctions, and / or potential component damage.

[0012] The vehicle can be a motor vehicle (e.g., a passenger car, truck, bus, or other motor vehicle or motorcycle), a train, a watercraft (e.g., a small boat or ship), or an aircraft (e.g., an airplane or helicopter). The vehicle can have an internal combustion engine and / or can have a drive battery (“electric vehicle”). An electric vehicle can be, for example, a plug-in hybrid vehicle (PHEV) or a fully electric drive vehicle, such as a battery-electric vehicle (BEV).

[0013] The on-vehicle energy network can have a uniform on-vehicle voltage or can have two or more sub-networks with different on-vehicle voltages, such as sub-networks of 12V and 400V.

[0014] An improvement is that the vehicle is a partially or fully autonomous vehicle.

[0015] The short-circuit line is in particular understood as an electrical connection between the monitored current path and the reference potential. In particular, electrical consumers are not included in the short-circuit line. The short-circuit line being open or off includes: in this state, no current (“short-circuit current”) can flow from the current path through the short-circuit line to the reference potential. The short-circuit line being closed or conducting includes: in this state, a “deliberately induced” high short-circuit current can flow from the current path through the short-circuit line to the reference potential.

[0016] One design is that when it is measured that the overvoltage has decreased, the short - circuited line is re - opened. This corresponds to the following situation: Advantageously, the short - circuited line is closed or switched to conduction until the overvoltage has actually decreased, which can be determined, for example, by voltage measurement. One design is that the short - circuited line is re - opened after a predetermined duration. This corresponds to the following situation: The short - circuited line is closed until the expected overvoltage is to be reduced. For this purpose, the duration is advantageously set such that it at least roughly corresponds to the duration of the transient voltage pulse typical for the type of consumer. With this design, the following advantage is achieved: The short - circuit current can be ended without measurement, which is particularly easy and fast to implement. More precisely, for example, a simple timer or a corresponding timer function can be used.

[0017] This task is also solved by a vehicle having an on - vehicle energy network, which is configured to perform the above - mentioned method. The vehicle can be configured similarly to the method, and vice versa, and has the same advantages.

[0018] One design is that the vehicle has at least:

[0019] - A consumer and another component, which is connected to the consumer through a current path carrying the supply voltage,

[0020] - A voltage measuring device for measuring the voltage on the current path,

[0021] - A short - circuited line connected between the current path and the reference potential, which short - circuited line has a switch and a current limiter in series therewith, and

[0022] - A switching device, which is configured such that when the voltage measured by the voltage measuring device is still lower than a predetermined first threshold, the switch is kept open or off; when the measured voltage reaches or exceeds the first threshold, the switch is closed or switched to conduction; and when the measured voltage reaches or is lower than a predetermined second threshold, the switch is re - opened.

[0023] The reference potential or ground corresponds in particular to the vehicle body or the bus bar.

[0024] The voltage measuring device can also be referred to as a "voltage sensor". The voltage measuring device is particularly arranged between the current path to be monitored and the switch. In a particularly simple embodiment, the voltage measuring device is configured as an over - voltage sensor, which over - voltage sensor only outputs or switches an output signal when the measured voltage reaches or exceeds a threshold indicating over - voltage. The over - voltage sensor can be, for example, a comparator circuit including a pre - voltage divider or having such a circuit.

[0025] A switch, especially an electronic switch, in particular a semiconductor switch, especially a power semiconductor switch. In an improved solution, the switch is a transistor, such as a field-effect transistor, such as a MOSFET. The switch is switched by a switching device and is connected to the switching device for this purpose, in particular via at least one signal line, especially a data line.

[0026] The current limiter limits the short-circuit current flowing through the closed short-circuit line and thus prevents damage or even destruction of the short-circuit line (including the wire and associated components). The current limiter can also be set to change the current flowing through it. This is especially beneficial for preventing the short circuit from having a significant impact on the vehicle electrical energy network. The change can be selected, for example, according to the connection situation and the system state. The current limiter can be, for example, an ohmic resistor or a transistor circuit.

[0027] The switching device is connected to the voltage measuring device via a signal line, especially a data line, and is especially configured to compare the measurement signal or measurement data transmitted by the voltage measuring device with a first threshold value and possibly a second threshold value and to control the switch accordingly based on the comparison result.

[0028] The first threshold value and the second threshold value can be the same or different. If the second threshold value is different, it can especially be lower than the first threshold value.

[0029] In an improved solution, the other component has a (protection) switch that disconnects the other component from the vehicle electrical energy network when an overvoltage is determined to exist on the other component. However, triggering can be disadvantageous when the switch reacts sluggishly and thus interrupts the power supply to the consumer for a long time. In addition, disadvantages can also occur when other consumers are also connected to the other component and are affected by the triggering of the protection switch. A design solution is that triggering a short circuit through the short-circuit line occurs faster than the triggering of the protection switch of the other component, because in this way the triggering of the protection switch can be prevented particularly reliably. This can also be described as that the other component has an overvoltage protection switch that triggers when an overvoltage exists in the current path, and the short-circuit line is configured to close faster or earlier than the overvoltage protection switch triggers when an overvoltage in the current path is determined.

[0030] In an improved solution, the time until a short circuit is triggered through the short-circuit line is shorter than the fault tolerance time of the other component or the fault tolerance time of the endangered part of the other component and / or the fault tolerance time of the consumer or the fault tolerance time of the endangered part of the consumer. The fault tolerance time is especially understood as the duration within which the component can "withstand" an overcurrent without damage.

[0031] The other component can for example be a DC voltage converter, a control device, a so-called companion system (steering, braking, lighting, windshield wipers, collision module, etc.) or a component for partial or fully autonomous driving.

[0032] In one design, the other component is an electrical energy storage device, in particular a battery, such as a lithium-ion battery, but it can also be a capacitor, such as a supercapacitor, etc. Batteries usually cannot or can only absorb feedback current for a short time due to their size and / or cell characteristics. The battery can have a battery (protection) switch.

[0033] In one design, the current path connects the positive pole of the electrical energy storage device to the power supply input of the consumer.

[0034] In one design, the consumer is an electrical braking system, an electrical front axle steering device or an electrical rear axle steering device, a DC voltage converter, windshield wipers or a fan. These components are safety-related and often tend to generate feedback current.

[0035] In one design, the short-circuit line also has a fuse element. The fuse element advantageously prevents damage to the short-circuit line particularly reliably, for example during particularly high and / or long-lasting transient processes or in the event of a fault. An improvement is that the fuse element is an electronic fuse device (also called an "electronic fuse") or has an electronic fuse device.

[0036] An improvement is that the short-circuit line has another or a second voltage measuring device, which is arranged between the switch and the reference potential. The other voltage measuring device measures the voltage at the reference potential of the switch. Thus, in this improvement, two voltage measuring devices are provided before and after the switch. This brings the advantage of redundancy and the possibility of evaluating the switch state, for example for verifying the successful switching of an electronic switch, also in cases other than overvoltage reduction, for example for functional checks.

[0037] In one design, the short-circuit line is configured as a short-circuit module, the first connection terminal of which is connected to the monitored current path and the second connection terminal of which is connected to the reference potential. The module can be installed and connected to the vehicle electrical energy network particularly easily.

[0038] In one design, the switching device and / or the voltage measuring device are components of the short-circuit module. This allows a particularly simple and compact structure. However, in addition to the switch and the current limiter, the module components, i.e. for example the voltage measuring device, the other voltage measuring device, the fuse element and / or the switching device, can also be arranged outside the module.

[0039] The following schematic description of an embodiment in conjunction with the drawings will more clearly and definitely understand the above characteristics, features and advantages of the present invention and the ways to achieve them, and this embodiment will be further described in conjunction with the drawings. Detailed implementation manner

[0040] Figure 1 A schematic diagram of a vehicle 1 having an on-vehicle energy network 2 is shown. On this on-vehicle energy network, at least one consumer 3 can be supplied with electrical energy and thus can operate. For this purpose, the power supply input terminal of the consumer is connected to the positive pole of another component of the on-vehicle energy network 2 in the form of an electrical energy storage device 5 (such as a battery, especially a lithium-ion battery) through a current path 4. Therefore, the current path 4 carries the supply voltage for the consumer 3. On the other hand, the negative poles of the consumer 3 and the energy storage device 5 are connected to a reference potential or ground GND (such as the vehicle body).

[0041] The current path 4 and the ground GND can be controllably electrically connected through a short-circuit line 18. For this purpose, a short-circuit module 6 is arranged between the current path 4 and the ground GND. The first connection terminal 6a of the short-circuit module is connected to the current path 4, and the second connection terminal 6b of the short-circuit module is connected to the ground. A voltage measuring device 7 for measuring the voltage applied to the current path 4, an electronic switch 8 (such as a MOSFET), and a current limiter 9 (such as an ohmic resistor or a transistor circuit) are arranged in series between the connection terminals 6a and 6b.

[0042] In addition, the short-circuit module 6 includes a switching device 10 for switching the switch 8, and is connected to the switch 8 through a signal line 11, especially a data line. A switching signal is output to the switch 8 through this signal line, for example, a switching signal is output to the gate connection terminal of the MOSFET used as the switch 8.

[0043] The switching device 10 is also connected to the voltage measuring device 7 through a signal line 12, especially a data line, and thus receives the measurement signal or measurement data of the voltage measuring device 7. Here, the switching device 10 is constructed as an evaluation device in addition to being used for switching, and can evaluate the received measurement signal or measurement data. The switching device 10 can especially be constructed as a logic component, and for example, has a computing core, a data memory, a possible A / D converter, etc. Here, the evaluation is carried out as follows: The measurement signal or measurement data is compared with a first threshold. If the voltage measured on the current path 4 is lower than the first threshold (which usually represents a normal situation without faults), the switching device 10 keeps the switch 8 off, and no current flows through the short-circuit module 6.

[0044] If, via the switching device 10, an overvoltage is determined such that the measured signal or the measured data reaches or exceeds a first threshold value, the switch 8 is controlled to be closed. Thereby, a high current flows through the short - circuit module 6, the magnitude of which is mainly determined by the current limiter 9. Based on this current flow, the overvoltage, especially the transient overvoltage, is reduced. If subsequently the measured signal or the measured data reaches or exceeds a predetermined second threshold value from above, the switch 8 is controlled to be opened again, so that the short - circuit current is interrupted. The second threshold value can be equal to or different from the first threshold value, especially smaller. The first threshold value and the second threshold value can be set, for example, programmed into the switching device 10, such that they are adapted to the overvoltage resistance of the energy storage 5.

[0045] Alternatively or additionally, the function of a timer or a timekeeper can be integrated into the switching device 10, such that it opens the switch 8 again after a predetermined duration has elapsed. This duration can be set, for example, programmed into the switching device 10, such that the duration corresponds to the duration of a typical transient generated by the consumer 3 on the current path 4. The duration can especially depend on the magnitude of the overvoltage.

[0046] Optionally, a fuse element 13 can also be present in series, such as a contactor, an electronic fuse device or an electronic fuse, etc. Thereby, damage to the short - circuit module 6 due to short - circuit current or a fault is advantageously reliably prevented.

[0047] Optionally, on the side opposite to the voltage measuring device 7 with respect to the switch 8, another voltage measuring device 14 can be present, which can be connected to the switching device 10, for example, via a signal line 15, especially a data line. In another embodiment, the short - circuit module 6 does not include the voltage measuring device 7, but rather a voltage measuring device 16 is arranged outside the short - circuit module 6, and this voltage measuring device transmits the measured signal or the measured data to the switching device 10 via a signal line 17, especially a data line.

[0048] In yet another embodiment, the switching device 10 is located outside the short - circuit module 6.

[0049] In one variant, the battery 5 has an over - voltage protection switch ("battery switch" 5a), which is triggered when an overvoltage exists on the current path. The voltage measuring device 7, the switching device 10 and the switch 8 are arranged such that the switch 8 closes significantly faster than the battery switch 5a when an overvoltage on the current path 4 is determined.

[0050] Of course, the present invention is not limited to the embodiments shown.

[0051] Generally, "a", "an", etc. are understood as singular or plural, especially in the sense of "at least one" or "one or more", unless explicitly excluded, for example, by expressions such as "exactly one", etc.

[0052] Similarly, numerical values include the specified numerical value and the usual tolerance range, unless explicitly excluded. List of reference numerals

[0053] 1 Vehicle

[0054] 2 On-vehicle energy network

[0055] 3 Consumer

[0056] 4 Current path

[0057] 5 Energy storage device

[0058] 5a Battery switch

[0059] 6 Short-circuit module

[0060] 6a First connection terminal

[0061] 6b Second connection terminal

[0062] 7 Voltage measuring device

[0063] 8 Switch

[0064] 9 Current limiter

[0065] 10 Switching device

[0066] 11 Signal line

[0067] 12 Signal line

[0068] 13 Fuse element

[0069] 14 Another voltage measuring device

[0070] 15 Signal line

[0071] 16 Voltage measuring device

[0072] 17 Signal line

[0073] 18 Short-circuit line

[0074] GND Reference potential / Ground

Claims

1. A method for reducing overvoltage, in particular transient overvoltage, in a current path (4) for carrying the supply voltage of a vehicle on-board energy network (2) of a vehicle (1), the current path being between a consumer (3) generating the overvoltage and another component (5), wherein, the voltage on the current path (4) is monitored, and when an overvoltage is determined, a short-circuit line (18) that was previously open between the monitored current path (4) and the reference potential (GND) is closed until the overvoltage has been reduced or is expected to be reduced.

2. The method according to claim 1, wherein When it is measured that the overvoltage has been reduced, the short-circuit line (18) is re-opened.

3. The method according to any one of the preceding claims, wherein The short-circuit line (18) is re-opened after a predetermined duration.

4. A vehicle (1) having a vehicle on-board energy network (2), the vehicle comprising at least: a consumer (3) and another component, the other component being connected to the consumer (3) via a current path (4) carrying the supply voltage; a voltage measuring device (7) for measuring the voltage on the current path (4); a short-circuit line (18) connected between the current path (4) and the reference potential (GND), the short-circuit line having a switch (8) and a current limiter (9) connected in series therewith; and a switching device (10) configured to: keep the switch (8) open when the voltage measured by the voltage measuring device (7) is still below a predetermined first threshold; close the switch (8) when the measured voltage reaches or exceeds the first threshold; and re-open the switch (8) when the measured voltage reaches or is below a predetermined second threshold.

5. The vehicle (1) according to claim 4, wherein, The other component (5) is an electrical energy storage device.

6. The vehicle (1) according to claim 5, wherein, The current path (4) connects the positive pole of the electrical energy storage device (5) to the supply input of the consumer (3).

7. The vehicle (1) according to any one of claims 4 to 6, wherein, The consumer (3) is an electric braking system, an electric front axle steering device or an electric rear axle steering device.

8. The vehicle (1) according to any one of claims 4 to 7, wherein, The short-circuit line (18) has a fuse element (9), in particular an electronic fuse device.

9. The vehicle (1) according to any one of claims 4 to 8, wherein, The short-circuit line (18) is configured as a short-circuit module (6), a first connection terminal (6a) of the short-circuit module being connected to the monitored current path (4), and a second connection terminal (6b) of the short-circuit module being connected to the reference potential (GND).

10. The vehicle (1) according to claim 9, wherein, The switching device (10) and / or the voltage measuring device (7) are components of the short-circuit module (6).

11. The vehicle (1) according to any one of the preceding claims, wherein, The other component (5) has an overvoltage protection switch (5a) that is triggered when an overvoltage exists on the current path (4), and the short-circuit line (18) is arranged to close faster than the overvoltage protection switch (5a) is triggered when an overvoltage on the current path (4) is determined.

Images