Circuit arrangement and method for providing additional voltage supply in on-board electrical system, and on-board electrical system

Abstract

The invention relates to a circuit arrangement for providing an additional voltage supply in an on-board electrical system (5), the on-board electrical system (5) providing an input voltage to at least one consumer (22) via a supply path (20), the circuit arrangement (10) is arranged in parallel to the power supply path (20) and has an energy store (12), a detection circuit (16) provided for monitoring an input voltage of at least one consumer, and a first switch (18) provided for switching the energy store (12), the circuit arrangement (10) being further provided for actuating the first switch (18) as a function of the result of the monitoring. The invention relates to a method for providing an additional voltage supply in an on-board electrical system (5) and to a corresponding on-board electrical system.

Description

Technical Field

[0001] The invention relates to a circuit arrangement for an additional voltage supply in an onboard electrical system, in particular in an onboard electrical system in a vehicle, for example a motor vehicle, and to a method for providing an additional voltage supply in an onboard electrical system. The invention also relates to an onboard electrical system for carrying out the method, which is in particular designed for use in a vehicle. Background Art

[0002] The onboard power supply refers to the totality of all electrical components in a vehicle, especially a motor vehicle. The electrical consumers in such an onboard power supply must be supplied with electrical energy, for which a device for supplying power, such as a battery, is required. These devices for supplying power, hereinafter referred to as power supply devices, provide a supply voltage sufficient for operating the electrical consumers.

[0003] The energy supply or voltage supply in a control unit (ECU), in particular a central control unit, is subject to voltage fluctuations and voltage interruptions during operation. Therefore, it is necessary to ensure that voltage interruptions do not normally lead to a loss of the functions to be performed.

[0004] It is known to buffer the supply voltage with capacitors in order to ensure safe operation even in the event of a voltage interruption. The time period during which the voltage interruption exists is thus bridged.

[0005] In known solutions, the time that can be bridged in the event of a voltage interruption depends on the voltage provided at the time of the interruption. A higher voltage can therefore achieve a longer bridge. However, since the input voltage can fluctuate significantly, the time period that can be bridged changes very strongly.

[0006] It is important to consider that the energy that can be stored in a capacitor is proportional to the square of the voltage, i.e.:

[0007] E~U 2 .

[0008] Because capacitors have parameter margins under normal circumstances, capacitors are not effectively utilized because a higher voltage resistance is selected than under normal circumstances. For example, a capacitor with a voltage resistance of 35V is used for a 12V application. Summary of the invention

[0009] Based on this background, a circuit arrangement according to the invention, an onboard electrical system according to the invention and a method according to the invention are proposed. Embodiments are apparent from the description, the drawings and the summarized concept.

[0010] A circuit arrangement for an additional voltage supply in an onboard electrical system is proposed, wherein the onboard electrical system provides an input voltage to at least one electrical load via a power supply path. The onboard electrical system is used in particular in a vehicle, in particular in a motor vehicle.

[0011] The described circuit assembly is arranged in parallel with the power supply path of the vehicle power system and has an energy storage device and a detection circuit, wherein the detection circuit is configured to monitor the input voltage of the electrical load. The circuit assembly also has a first switch, which is configured to switch the energy storage device. This means that the switch can connect or disconnect the energy storage device according to its position. The circuit assembly is also configured to control the switch according to the monitoring result. This means that the switch is either opened or maintained or closed according to the monitoring result.

[0012] The proposed onboard electrical system has a power supply device and an electrical load, which are connected to one another via a power supply path. In this case, a circuit component of the type described here is arranged in parallel with the power supply path.

[0013] The onboard power system may have other power supply devices, power supply paths and electrical consumers. The circuit components described here may be assigned to one or more electrical consumers or power supply paths. Multiple circuit components of the described type may also be used. The significance of the electrical consumers may be considered for the operation of the onboard power system or the entire vehicle.

[0014] The proposed method is used for providing an additional voltage supply in an onboard electrical system of the type described here with a circuit assembly, as proposed here. In the method, a detection circuit of the circuit assembly monitors the input voltage of an electrical consumer of the onboard electrical system during operation. When the input voltage falls below a predetermined threshold value, a first switch of the circuit assembly is actuated so that the electrical consumer of the onboard electrical system is supplied with energy from an energy store.

[0015] The first switch of the circuit assembly is thus typically closed by a control signal so that the load in the onboard power supply is supplied with energy from the additional energy store. In this way, voltage fluctuations and voltage interruptions can be bridged, specifically independently of the voltage previously acting on the load.

[0016] This is possible because the additional energy store is an independent energy store which is charged to a predetermined voltage level. The maximum duration which can be bridged can therefore also be set by the parameters of the energy store.

[0017] The proposed method also makes it possible to protect a plurality of electrical consumers in the vehicle electrical system, which are supplied with energy, if necessary, via a plurality of energy stores, via supply lines.

[0018] Therefore, in the configuration with a boost regulator, the capacitor is charged to its technical maximum value and used as an energy store. When a voltage interruption is detected, the charged capacitor is switched on and thus supports the supply voltage for a predefined period of time.

[0019] In some embodiments, implementations with switches or ideal diodes are possible, for example.

[0020] The proposed method has a number of advantages, at least in some embodiments:

[0021] A more efficient use of capacitors as energy storage can be achieved, thereby resulting in fewer capacitors being required, which leads to potentially lower costs and less space requirements.

[0022] The length of time that can be bridged during an interruption is independent of the voltage at the time of the interruption, so that the required capacitance can be limited more precisely.

[0023] Further advantages and embodiments of the invention are apparent from the description and the accompanying drawings.

[0024] It goes without saying that the features mentioned above and those yet to be explained below can be used not only in the respectively specified combination but also in other combinations or alone without departing from the scope of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A block diagram is used to illustrate the circuit components used to implement the proposed invention;

[0026] Figure 2 A possible embodiment of the described method is shown in a flow chart. DETAILED DESCRIPTION

[0027] The present invention is schematically depicted in the drawings based on embodiments and is explained in detail below with reference to the drawings.

[0028] Figure 1 A circuit arrangement is shown, which is generally designated by the reference number 10 and is used in a vehicle electrical system 5. The illustration shows an energy storage device 12, which comprises a step-up regulator 14, for example for a voltage of 35 V, and several capacitors 15 connected in parallel. The step-up regulator 12, also called a step-up chopper, can charge the capacitor 15. A further capacitor 17 is also shown.

[0029] Also provided in the circuit arrangement 10 are a detection circuit 16 and a first switch 18 , which in this case is designed as an ideal diode with a switch input.

[0030] The illustration also shows a power supply path 20 which enables a load 22 to be supplied with power by a power supply device 24, for example a battery. A diode 26 and a second switch 28 are provided in the power supply path 20, which is likewise designed as an ideal diode in this case.

[0031] The energy store 12 is therefore designed in parallel with the conventional power supply path 20 and is charged to a higher voltage level, for example to 35 V, when connected to the power supply 24 . The detection circuit 16 detects when the input voltage drops below the level required by the load 22 .

[0032] In this case, energy is transmitted from the energy store 12 to the load 22 via the first switch 18. For this purpose, a corresponding control signal is generated by the detection circuit 16. The first switch 18 is actuated using this signal.

[0033] The second switch 28 may be alternatively connected relative to the first switch 18 .

[0034] The second switch 28 prevents the stored energy from flowing back into the vehicle electrical system. The diode 26 is optionally provided and serves to protect the step-up regulator 14 from reverse polarity. The switches 28 and 18 can be implemented as ideal diodes, for example with a controller IC with field effect transistor switches. This results in lower losses than in the case of "normal" diodes. Other switches, for example semiconductor switches, can also be used for the switches 28 and 18.

[0035] Figure 2 A possible sequence of embodiments of the described method is shown in a flow chart. In a first step 50, the motor vehicle is started to be operated with an onboard electrical system having a circuit assembly for an additional voltage supply in the manner described here. Such an onboard electrical system also has a power supply device and an electrical load. The power supply device provides an input voltage to the electrical load.

[0036] In a second step 52, the energy store is charged and the input voltage of the load is monitored at the same time. If the input voltage drops below a predetermined level in step 54, the energy store is typically activated or switched on via a switch in step 56. The load is thus additionally or optionally also completely supplied by the energy store.

Claims

1. A circuit assembly for providing an additional voltage supply in an onboard electrical system (5), wherein: The onboard power supply system (5) supplies an input voltage to at least one electrical load (22) via a power supply path (20), wherein the circuit component (10) is arranged in parallel with the power supply path (20) and has: Energy storage device (12), a detection circuit (16) configured to monitor an input voltage of the at least one electrical consumer, and A first switch (18) is configured to switch the energy storage device (12), wherein: The circuit assembly (10) is further configured to actuate the first switch (18) according to a result of the monitoring.

2. The circuit arrangement as claimed in claim 1, in which the energy store (12) has at least one capacitor (15).

3. The circuit arrangement as claimed in claim 1 or 2, in which a charge regulator is provided for charging the energy store (12).

4. The circuit arrangement as claimed in claim 3, in which the step-up regulator (14) is used as a charge regulator. 5 . The circuit arrangement according to claim 1 , in which the first switch ( 18 ) is designed as an ideal diode.

6. A vehicle electrical system having a power supply device (24) and an electrical load (22), wherein the power supply device and the electrical load are connected to each other via a power supply path (20), wherein: A circuit assembly (10) according to any one of claims 1 to 5 is arranged in parallel with the power supply path (20).

7. The onboard electrical system according to claim 6, wherein a second switch (28) is arranged in the power supply path (20).

8. The onboard electrical system according to claim 7, in which the second switch (28) is designed as an ideal diode.

9. The onboard electrical system according to claim 6, wherein a diode (26) is provided in the power supply path (20) for reverse polarity protection.

10. A method for providing an additional voltage supply in an on-board power supply system (5) according to any one of claims 6 to 9, the on-board power supply system having a circuit component (10) according to any one of claims 1 to 5, in which method the detection circuit (16) of the circuit component (10) monitors the input voltage of an electrical consumer (22) of the on-board power supply system (5) and operates a first switch (18) of the circuit component (10) when the input voltage is below a predetermined threshold value so that the electrical consumer (22) is supplied with energy from the energy storage device (12). 11 . The method as claimed in claim 10 , in which the energy store ( 12 ) of the circuit component ( 10 ) is charged during operation of the onboard electrical system ( 5 ). 12 . The method according to claim 11 , in which the energy store ( 12 ) is charged to a higher energy level than the energy level of a power supply ( 24 ) of the onboard electrical system ( 5 ).

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