Device for stabilizing a voltage supply in an on-board electrical system of a vehicle

Abstract

The device (7) for stabilizing a voltage supply in an on-board electrical system of a vehicle comprises a first connection (T1) for direct or indirect connection to an energy source (3) and a second connection (T2) for direct or indirect connection to at least one load (5) of the on-board electrical system. The device (7) also comprises a first buffer capacitor (CP1) which is arranged in a first branch (B1) which is connected to the second connection (T2) and a reference potential. The device (7) comprises a buffer capacitor arrangement (11) having at least two capacitors (C1, C2) and a switchover apparatus having a plurality of controllable switches (S1, S2, S3). The buffer capacitor arrangement is arranged in parallel with the first buffer capacitor (CP1) and, when the switchover apparatus is in a first switching state, the at least two capacitors (C1, C2) are arranged in series and, when the switchover apparatus is in a second switching state, the at least two capacitors (C1, C2) are arranged in parallel branches. The device (7) also comprises a current sensor and a voltage sensor.

Description

[0001] Description

[0002] Device for stabilizing a voltage supply in a vehicle's electrical system

[0003] The invention relates to a device for stabilizing a voltage supply in a vehicle's electrical system. Furthermore, the invention relates to a method and a corresponding control device for stabilizing a voltage supply in a vehicle's electrical system. Furthermore, the invention relates to an electrical system stabilization system, a computer program, and a computer-readable medium.

[0004] Modern vehicles in particular contain dynamic electrical loads whose operation can cause a significant voltage drop, such as an anti-lock braking system or an electric steering drive used in parking assist systems. These dynamic loads, in particular, are also activated during vehicle operation, not just during the first cold start or when the vehicle is parked.

[0005] To absorb voltage spikes or dips and prevent adverse load performance, multiple batteries, such as lead-acid batteries, are currently deployed throughout the low-voltage vehicle electrical system. These batteries can partially absorb voltage spikes or dips. However, for highly dynamic loads, these batteries react too slowly. In addition, they are heavy. DCDC converters with a small number of supercapacitors, also known as ultracapacitors, are also used to solve this problem. However, such a circuit often does not react quickly enough and is therefore unsuitable for supporting very brief voltage dips.

[0006] The object underlying the invention is to provide a device for stabilizing a voltage supply in a vehicle's electrical system, which contributes to ensuring that the loads of an electrical system can be supplied reliably and / or cost-effectively and / or with a small installation space. This object is achieved by the features of the independent patent claims.

[0007] Advantageous embodiments are characterized in the subclaims.

[0008] According to a first aspect, the object is achieved by a device for stabilizing a voltage supply in an on-board electrical system of a vehicle. The device has a first connection for direct or indirect connection to a power source and a second connection for direct or indirect connection to at least one load of the on-board electrical system. Furthermore, the device has a first buffer capacitor arranged in a first branch that is connected to the second connection and a reference potential. The device comprises a buffer capacitor arrangement with at least two capacitors and a switching device that has a plurality of controllable switches. The buffer capacitor arrangement is arranged in parallel with the first buffer capacitor, and when the switching device has a first switching state, the at least two capacitors are arranged in series in a branch that is arranged parallel to the first branch.When the switching device has a second switching state, the at least two capacitors are arranged in at least two branches, each of which is connected in parallel with the first branch. Furthermore, the device comprises a current sensor configured to detect a first measurement signal representative of a current and / or a gradient of the current flowing in the second branch. The device further comprises a voltage sensor configured to detect a second measurement signal representative of a voltage applied to the first buffer capacitor.

[0009] The energy source can comprise an energy storage device, for example, a rechargeable battery and / or a DC / DC converter. The filter circuit and / or the filter element preferably have an inductive component or form an inductance. The filter element comprises, for example, a coil.

[0010] The device has the advantage that the buffer capacitor arrangement can help buffer voltage dips over a wide voltage range. In contrast to an arrangement with only one buffer capacitor connected in parallel with the load, the energy stored in the capacitors can be maximized, and a large current can be injected despite line inductances. The device enables broadband dynamic buffering of an on-board electrical system voltage. In at least one advantageous embodiment, the buffer capacitor arrangement has a filter circuit or a filter element. The filter circuit or the filter element advantageously enables damping of the current peaks.

[0011] In at least one advantageous embodiment according to the first aspect, the at least two capacitances of the buffer capacitance arrangement are formed by a first capacitance and a second capacitance, and the switching device is formed by a first controllable switch, a second controllable switch, and a third controllable switch.

[0012] The first capacitance and / or the second capacitance can each be formed by one or more discrete or distributed capacitors.

[0013] In at least one advantageous embodiment according to the first aspect, a second terminal of the second capacitance is connected to a first terminal of the third switch and to a first terminal of the second switch. Furthermore, a first terminal of the first switch is connected to the first and / or the second terminal of the device, a second terminal of the first switch is connected to the second terminal of the second switch, and a second terminal of the third switch is connected to a reference potential. Furthermore, a first terminal of the first capacitance is connected to the second terminal of the second switch, and a second terminal of the first capacitance is connected to the reference potential.

[0014] The filter circuit or the filter element is preferably arranged in series with the second capacitance.

[0015] Advantageously, such an arrangement with only a very small number of electronic components enables a rapid adaptation of the buffer capacitance arrangement to the load situation.

[0016] According to a second aspect, the object is achieved by a method for operating a device for stabilizing a voltage supply in an on-board electrical system according to the first aspect.

[0017] Here, a first measurement signal provided by the current sensor is received, which is representative of a current flowing in the second branch, and a gradient, in particular a temporal gradient, of the current is determined. Alternatively, a first measurement signal provided by the current sensor is received, which is representative of a gradient of the current flowing in the first branch. Furthermore, a second measurement signal provided by the voltage sensor is received, which is representative of a voltage across the first buffer capacitor.

[0018] When the switching device is in the first switching state, the controllable switches of the switching device are controlled depending on the determined gradient or the first measurement signal and the second measurement signal such that the switching device switches from the first switching state to the second switching state. Subsequently, as soon as the first measurement signal falls below a predetermined limit value and / or the second measurement signal lies within a predetermined nominal value range, the controllable switches of the switching device are controlled such that the switching device switches from the second switching state to a third switching state. Subsequently, as soon as a voltage across the second capacitor lies within a predetermined voltage range, the switches of the switching device are controlled such that the switching device switches from the third switching state to the first switching state.

[0019] In at least one embodiment according to the second aspect, in the first switching state of the switching device, the first switch and the third switch are closed, and the second switch is open. In the second switching state of the switching device, the first switch and the third switch are open, and the second switch is closed. In the third switching state of the switching device, the second switch and the third switch are closed, and the first switch is open.

[0020] Advantageous embodiments according to the first aspect also apply to the second aspect.

[0021] According to a third aspect, the object is achieved by a control device configured to carry out the method according to the second aspect. Advantageous embodiments according to the first and second aspects also apply to the third aspect.

[0022] According to a fourth aspect, the object is achieved by an on-board power system stabilization system for a vehicle. The on-board power system stabilization system comprises a device for stabilizing a voltage supply according to the first aspect and a control device according to the third aspect.

[0023] Advantageous embodiments of the first and third aspects also apply to the fourth aspect.

[0024] According to a fifth aspect, the object is achieved by a computer program comprising instructions which, when the program is executed by a control computer, cause the control computer to carry out the method according to the second aspect.

[0025] For the purposes of this document, the term "computer program" refers to a program element and / or a software module and / or a computer program product containing instructions for controlling the control computer to coordinate the operation of the system or method in a suitable manner to achieve the effects associated with the method according to the invention. The computer program can be implemented as computer-readable instruction code in any suitable programming language, such as JAVA, C++, etc.

[0026] The control computer includes a processor and a program memory. Alternatively, the program memory may be associated with the control computer. The processor may include a central processing unit (CPU). The processor may be a general-purpose processor, a microprocessor, a microcontroller, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or another programmable logic device, a discrete gate or transistor logic device, a discrete hardware component, or the like.

[0027] According to a sixth aspect, the object is achieved by a computer-readable medium comprising instructions which, when executed by a control computer, cause the control computer to carry out the method according to the second aspect. Advantageous embodiments according to the first aspect also apply to the fifth and sixth aspects.

[0028] The computer program can be stored on a computer-readable storage medium (CD-ROM, DVD, Blu-ray disk, removable drive, volatile or non-volatile memory, in particular random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM), and / or flash memory. The storage medium can be a memory built into the processor, a memory arranged externally of the processor on a module, or a portable memory. The memory is configured to store associated program instructions and associated data.

[0029] Furthermore, the computer program may be provided on a network such as the Internet, from which it can be downloaded by a user when required.

[0030] Embodiments of the invention are explained below with reference to the schematic drawings. The description of the subject matter specified here is not limited to the individual specific embodiments. Features of different embodiments can be combined with one another—where technically feasible—to form further embodiments. For example, variations or modifications described with regard to one of the embodiments may also be applicable to other embodiments, unless otherwise stated.

[0031] They show:

[0032] Figure 1 is an equivalent circuit diagram of an embodiment of an on-board power system of a vehicle,

[0033] Figure 2 shows a further, more detailed equivalent circuit diagram of an embodiment of the on-board power system and

[0034] Figure 3 shows a flowchart of an embodiment of a program for operating the device for stabilizing a power supply. In the figures, the same reference numerals are used for elements with essentially the same function; however, these elements need not be identical in every detail.

[0035] It should be noted that when an element is described as being "connected" or "coupled" to another element, the element may be directly connected or coupled to the other element, or intervening elements may be present. Conversely, when an element is described as being "directly connected" or "coupled" to another element, no intervening elements are present. Other terms used to describe the relationship between elements should be interpreted similarly (e.g., "between" versus "directly between," "adjacent" versus "directly adjacent," etc.).

[0036] Figure 1 shows an equivalent circuit diagram of an embodiment of an on-board power system 1 of a vehicle.

[0037] The on-board electrical system 1 comprises a power source 3, for example, a battery and / or a DC / DC converter. Furthermore, the on-board electrical system 1 comprises at least one load 5 and an on-board electrical system stabilization system with a device 7 and a control device 9 for stabilizing a voltage supply of the on-board electrical system. The load 5 and the device 7 are each connected to the power source 3 via lines. The lines each have parasitic line inductances L2, L3.

[0038] The device 7 has a first terminal T1 which is directly or indirectly connected to the energy source 3. Furthermore, the device 7 has a second terminal T2 which is directly or indirectly connected to the at least one load 5 of the vehicle electrical system. The device 7 comprises a first buffer capacitor CP1 which is arranged in a first branch B1 which is connected to the second terminal T2. The first branch B1 with the first buffer capacitor CP1 is arranged in particular in parallel to a load branch BL in which the load 5 is arranged. The device 7 comprises a buffer capacitor arrangement 11 with at least two capacitors and a switching device which has a plurality of controllable switches. The buffer capacitor arrangement 11 is arranged in parallel to the first buffer capacitor CP1.Here, when the switching device has a first switching state, the at least two capacitors are arranged in series in a second branch B2, which is arranged in parallel with the first branch B1. However, when the switching device has a second switching state, the at least two capacitors are arranged in at least two branches, each of which is connected in parallel with the first branch B1.

[0039] The device 7 further comprises a current sensor (not shown in Figure 1). The current sensor is configured to detect a first measurement signal representative of a current and / or gradient of the current flowing in the second branch B2.

[0040] Furthermore, the device 7 comprises a voltage sensor (not shown in Figure 1). The voltage sensor is configured to detect a second measurement signal representative of a voltage applied to the first buffer capacitor CP1.

[0041] The switching device is formed, for example, by a first switch S1, a second switch S2, and a third switch S3. The buffer capacitor arrangement 11 has, for example, a first capacitor C1 and a second capacitor C2 as the at least two capacitors.

[0042] In an exemplary embodiment, a second terminal of the second capacitance C2 is connected, in particular directly connected, to a first terminal of the third switch S3 and to a first terminal of the second switch S2. A first terminal of the first switch S1 is connected, in particular directly connected, to the first terminal T1 and / or second terminal T2 of the device 7, and a second terminal of the first switch S1 is connected, in particular directly connected, to the second terminal of the second switch S2. A second terminal of the third switch S3 is connected to a reference potential, and a first terminal of the first capacitance C1 is connected, in particular directly connected, to the second terminal of the second switch S2, and a second terminal of the first capacitance C2 is connected to the reference potential.

[0043] The buffer capacitor arrangement 11 comprises, for example, a filter inductance LF, which is connected in series with the second capacitor C2 and is connected to the first terminal T1 and / or the second terminal T2. The switches S1, S2, S3 of the switching device can be controlled by the control device 9 such that

[0044] - in the first switching state of the switching device, the first switch S1 and the third switch S3 are closed and the second switch S2 is open,

[0045] - in the second switching state of the switching device, the first switch S1 and the third switch S3 are open and the second switch S2 is closed, and

[0046] - in a third switching state of the switching device, the second switch S2 and the third switch S3 are closed and the first switch S1 is open.

[0047] Figure 2 shows a further, more detailed equivalent circuit diagram of an embodiment of the on-board power system 1.

[0048] The switches S1, S2, S3 of the switching device each comprise, for example, a transistor M1, M2, M3, in particular a MOSFET (metal oxide semiconductor field-effect transistor). For example, the MOSFETs are designed as normally-off N-channel MOSFETs.

[0049] The first terminal of the first switch S1 and the first terminal of the third switch S3 are connected, for example, to a drain terminal of the respective transistor M1, M3 or are formed by it. The second switch S2 has a different orientation. The first terminal of the second switch S2 is connected, for example, to the source terminal of the transistor M2 or is formed by it.

[0050] The changed orientation of the transistor M2 of the second switch S2 prevents a short-circuit of the first capacitor C1 when the third switch S3 is closed or the transistor M3 of the third switch S3 is conducting.

[0051] A linear region of the respective transistors M1, M2, M3 can be controlled by the control device in such a way that inrush currents can be limited.

[0052] Figure 3 shows a flowchart of an embodiment of a program for operating the device 7 for stabilizing a voltage supply.

[0053] The program is executed, for example, by a control computer, which may also be referred to as control device 9. The program is started, for example, with an activation of the vehicle, in which the vehicle is moved from a parking mode into a commissioning mode, which is executed before the engine is started.

[0054] The program starts, for example, in step S01. In step S01, program variables are initialized.

[0055] In step S03, a first measurement signal provided by the current sensor is received, which is representative, for example, of a current flowing in the second branch B2, and a gradient of the current is determined. Furthermore, a second measurement signal provided by the voltage sensor is received, which is representative of a voltage across the first buffer capacitor CP1.

[0056] In a step S05, when the switching device has the first switching state, the controllable switches S1, S2, S3 of the switching device are controlled depending on the determined gradient or on the first measurement signal and the second measurement signal such that the switching device changes from the first switching state to the second switching state.

[0057] Thus, starting from a normal state in which the first switch S1 and the third switch S3 are closed and the second switch S2 is open, if, for example, a voltage drop occurs and / or the load 5 suddenly draws a high current, causing the supply voltage to drop due to the line inductances and resistances, the first switch S1 and the third switch S3 are closed and the second switch S2 is opened. Depending on the current gradient in the first branch and a voltage drop across the first buffer capacitance CP1, the program decides to support the supply voltage and open the first switch S1 and the third switch S3 and close the second switch S2. Thus, the first capacitance C1 and the second capacitance C2 of the buffer capacitance arrangement 11 are connected in series and raise the voltage across the parasitic line inductance L3 in the supply line to the load 5.As a result, despite the load-side line inductance L3, a high current is impressed through the load-side line inductance L3, so that the voltage at load 5 does not drop significantly.

[0058] In a step S07, as soon as the first measurement signal falls below a predetermined limit value and / or the second measurement signal lies within a predetermined nominal value range, the controllable switches S1, S2, S3 of the switching device are then controlled such that the switching device changes from the second switching state to a third switching state and, if a voltage at the second capacitor C2 is subsequently within a predetermined voltage range, the switches S1, S2, S3 of the switching device are controlled such that the switching device changes from the third switching state to the first switching state.

[0059] Thus, as soon as the capacitances C1, C2 of the buffer capacitance arrangement 11 are discharged and no more current flows from the buffer capacitance arrangement 11 into the vehicle electrical system and / or the supply voltage is restored or the nominal voltage is reached, the second switch S2 is opened again and the third switch S3 is immediately closed.

[0060] Subsequently, in a step S09, as soon as the voltage at the second capacitor C2 reaches or exceeds the nominal supply voltage plus a predetermined hysteresis value HO, the first switch S1 is closed to charge the first buffer capacitor CP1.

[0061] Once the capacitors C1, C2 in the buffer capacitor array 11 are loaded, the program continues in step S03. For example, in an optional step S11, it is checked whether the capacitors C1, C2 in the buffer capacitor array 11 are loaded. If the capacitors C1, C2 of the buffer capacitor array 11 are loaded, the program continues in step S03.

[0062] The program is terminated, for example, in step S13 when the vehicle enters parking mode.

[0063] 1 on-board power system

[0064] 3 Energy source

[0065] 5 Last

[0066] 7 Device

[0067] 8 Buffer capacitor arrangement

[0068] 9 Control device

[0069] B1 first branch

[0070] BL load branch

[0071] C1 first capacity

[0072] 02 second capacity

[0073] CP first buffer capacitor

[0074] M1, M2, M3 transistors

[0075] T1 first connection

[0076] T2 second connection

[0077] L2, L3 line inductance

[0078] LF filter element

[0079] S1, S2, S3 switches

[0080] S01 ... S13 program steps

[0081] UL load voltage

[0082] IL load current

[0083] UGS1 gate-source voltage

Claims

Patent claims 1 . Device (7) for stabilizing a voltage supply in an on-board network of a vehicle, comprising - a first terminal (T1) for direct or indirect connection to an energy source (3), - a second terminal (T2) for direct or indirect connection to at least one load (5) of the vehicle electrical system, - a first buffer capacitor (CP1 ) arranged in a first branch (B1 ) connected to the second terminal (T2) and a reference potential, - a buffer capacitance arrangement (11) with at least two capacitances (C1, C2) and a switching device having a plurality of controllable switches (S1, S2, S3), wherein the buffer capacitance arrangement (11) is arranged in parallel with the first buffer capacitance (CP1) and, when the switching device has a first switching state, the at least two capacitances (C1, C2) are arranged in series in a second branch (B2) which is arranged in parallel with the first branch (B1) and, when the switching device has a second switching state, at least one of the capacitances (C2) is arranged in the second branch (B2) and at least one capacitance (C1) of the at least two capacitances (C1, C2) is arranged in a third branch which is connected in parallel with the second branch (B2), - a current sensor configured to detect a first measurement signal representative of a current and / or gradient of the current flowing in the second branch (B2), - a voltage sensor configured to detect a second measurement signal representative of a voltage applied to the first buffer capacitance (CP1).

2. Device (7) according to claim 1, wherein the buffer capacitor arrangement (11) further comprises a filter circuit or a filter element (LF).

3. Device (7) according to claim 1, wherein - the buffer capacity arrangement (11) comprises a first capacity (C1) and a second capacity (C2) as the at least two capacities, - the switching device comprises a first controllable switch (S1), a second controllable switch (S2) and a third controllable switch (S3).

4. Device (7) according to claim 3, wherein - a second terminal of the second capacitor (C2) is connected to a first terminal of the third switch (C3) and to a first terminal of the second switch (S2), - a first terminal of the first switch (C1) is connected to the first and / or second terminal (T1, T2) of the device (7) and a second terminal of the first switch (S1) is connected to the second terminal of the second switch (S2), - a second terminal of the third switch (S3) is connected to a reference potential, - a first terminal of the first capacitance (C1) is connected to the second terminal of the second switch (S2) and a second terminal of the first capacitance (C1) is connected to the reference potential.

5. A method for operating a device (7) for stabilizing a voltage supply in an on-board network according to one of claims 1 to 4, wherein - a first measurement signal provided by the current sensor is received, which is representative of a current flowing in the second branch (B2), and a gradient of the current is determined, or a first measurement signal provided by the current sensor is received, which is representative of a gradient of the current flowing in the first branch (B2), - a second measurement signal provided by the voltage sensor is received, which is representative of a voltage at the first buffer capacitance (CP1 ) and - when the switching device has the first switching state, depending on the determined gradient or the first measurement signal and the second measurement signal, the controllable switches (S1, S2, S3) of the switching device are controlled such that the switching device changes from the first switching state to the second switching state, and then, when the first measurement signal falls below a predetermined limit value and / or the second measurement signal lies within a predetermined nominal value range, the controllable switches (S1, S2, S3) of the switching device are controlled such that the switching device changes from the second switching state to a third switching state, and when a voltage across the second capacitor (C2) is subsequently within a predetermined voltage range, the switches (S1, S2, S3) of the switching device are controlled such that the switching device changes from the third switching state to the first switching state.

6. The method according to claim 5, wherein - in the first switching state of the switching device, the first switch and the third switch are closed and the second switch is open, - in the second switching state of the switching device, the first switch and the third switch are open and the second switch is closed, - in the third switching state of the switching device, the second switch and the third switch are closed and the first switch is open.

7. Control device (9) which is designed to carry out the method according to claim 5 or 6.

8. On-board power system stabilization system for a vehicle comprising a device (7) for stabilizing a voltage supply according to one of claims 1 to 4 and a control device (9) according to claim 7.

9. A computer program comprising instructions which, when executed by a control computer, cause the control computer to carry out the method according to one of claims 5 and 6.

10. A computer-readable medium comprising instructions which, when executed by a control computer, cause the control computer to carry out the method according to any one of claims 5 and 6.

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