EP3370991A1

EP3370991A1 - Method for monitoring a vehicle electric supply system

Info

Publication number: EP3370991A1
Application number: EP16784183.2A
Authority: EP
Inventors: Christian Bohne
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2015-11-05
Filing date: 2016-10-19
Publication date: 2018-09-12
Also published as: WO2017076642A1; DE102015221729A1

Abstract

The invention relates to a method for operating a vehicle supply system (200) comprising at least two channels with at least one component (210), and a power supply; a coupling element (202) located between the two channels is used to perform at diagnosis, at least one measurement being taken in the coupling element (202).

Description

Description title

Method for monitoring an electrical system

The invention relates to a method for monitoring an electrical

On-board network and a vehicle electrical system for carrying out the method.

State of the art

Under an electrical system is to be understood in the automotive use, the totality of all electrical components in a motor vehicle. Thus, these include both electrical consumers and supply sources, such as, for example, generators or electrical storage, such as batteries. Furthermore, it also includes all electrical connection and distribution elements such as cable or harness, power distribution and fuse boxes. In the motor vehicle care must be taken to ensure that electrical energy is available in such a way that the motor vehicle can be started at any time and that sufficient power is available during operation. But even when parked, electrical consumers should still be operable for a reasonable period of time, without a subsequent start being impaired.

It should be noted that due to the increasing electrification of

Aggregates and the introduction of new driving functions, the requirement for the reliability of the electrical energy supply in the motor vehicle steadily increases. Furthermore, it has to be considered that in the future with a

highly automated driving should be permitted to a limited extent. A sensory, regulatory, mechanical and energetic fallback by the driver in this case is limited. Therefore, in a highly automatic driving, the electric power supply has hitherto unknown in motor vehicles Safety relevance. Errors in the electrical system must therefore be reliably and completely recognized.

Under a highly automatic driving, which is also referred to as highly automated driving, an intermediate step between an assisted driving in which the driver is assisted by assistance systems, and an autonomous driving in which the vehicle drives automatically and without the driver's intervention, to understand. In the case of highly automatic driving, the vehicle has its own intelligence that could plan ahead and take on the driving task, at least in most driving situations. Therefore, in a highly automatic driving, the electrical supply has a high

Safety relevance.

With on-board errors in sources, memories and consumers, the wiring harness also plays a role. On the one hand, faults such as interruptions and short circuits can occur in the wiring harness and connectors, on the other hand, contact resistances can also be increased. There are no diagnoses for this in today's vehicles. On the other hand, it is already known to measure the vehicle electrical system voltage within components. Both the electric steering, the ESP, and other control devices measure the terminal voltage. Then the operating behavior of the components is adjusted. This is done, for example. By switching off or degradation of the function at undervoltage, z. B. less than 9 V, or overvoltage, for example. More than 16 V.

Furthermore, it is known that a battery sensor EBS measures the terminal voltage and the battery current of the lead-acid battery in order, for example, via the

Closed circuit voltage to close the state of charge of the battery.

The document WO 2010121075 A2 describes a method for detecting errors in a circuit arrangement. In this case, the cell voltages of a high-voltage battery are used to close from the comparison with a second voltage at a point in the wiring harness during a defined load current to contact resistances in the high-voltage electrical system and in the cell connections. If the contact resistances are too high, charge or discharge currents should be limited to prevent thermal overheating to avoid. However, the document does not describe how the

Supply of safety-relevant consumers in the low-voltage on-board electrical system

is to ensure.

The monitoring of a lead-acid battery by an electronic battery sensor (EBS) is known from document WO 2013/139547 AI.

The monitoring of consumers by fuses or

Electronic fuses is known from the document DE 100 36 983 AI, which describes a device for fast short-circuit protection in a power semiconductor.

The document DE 103 23 145 A1 describes a method for checking an electrical machine, for example a generator. The generator is connected in a vehicle electrical system of a motor vehicle with a battery and a control unit and is driven by an internal combustion engine of the motor vehicle. In the presented method, the generator with the aid of a battery sensor on the basis of determined measured values of the

Battery currents tested.

The methods described above relate primarily to single-channel vehicle electrical system with generator. With the introduction of automatic driving functions, however, two-channel vehicle electrical systems are needed.

Disclosure of the invention

Against this background, a procedure with the characteristics of the

Claim 1 and an electrical system according to claim 12 presented.

Embodiments emerge from the dependent claims and from the description.

The method takes into account that, in the case of two-channel on-board networks, coupling elements are provided, for example, in the form of intelligent switches or DC or DC / DC converters between the two on-board networks. The presented method makes it possible, by means of extensions of the method discussed above, to have a single-channel or two-channel vehicle electrical system

To systematically diagnose the coupling elements in order to make the sensors in the EBS and the DC / DC converter plausible and to recognize the following errors:

- incorrect current measurement in the EBS, DC / DC converter, electronic fuse or consumer, if they exist,

- incorrect voltage measurement in EBS, DC / DC converter, electronic fuse or consumer,

- Failure of battery or DC / DC converter.

The presented method also makes it possible to diagnose the power consumption of consumers or electronic fuses

plausibility. This makes possible:

- monitoring the power consumption of consumers,

- monitoring the correct shutdown of electronic fuses in the event of overload,

- Monitoring the quiescent current recording in standby mode

Consumers.

In addition, the described method allows detection of harness failures, such as supply-to-ground shorts or increased contact resistances, for example:

- in the line from the lead-acid battery to a junction Kl,

- in the fuse box, including internal wiring, fuse holders, fuses, etc., - in cables and plugs of the individual components,

- In the ground lines of the respective component to the ground bolt on the body or to the ground point in Zweileiterbordnetzen.

It is thus presented a method for systemic diagnosis of the electrical system by combining existing signals. This includes the application of the Kirchoffschen node rule for checking the currents in a network. By comparing the signals of existing current sensors or by determining the load current based on drive signals of

Consumers should be tested against each other.

Furthermore, the method makes it possible to selectively control loads or the DC / DC converter in order to selectively check the electrical system on the basis of the conditions thus induced. The procedure sees a comparison of

Voltage measurements at various points in the electrical system, specifically in energy sources, sinks and distribution elements, before. Depending on the respective load current, which can be determined by existing signals or control signals from consumers, thus short circuits or

increased contact resistance can be detected.

An advantage of the method described is that existing

To use information for new diagnoses or to operate components specifically in such a way that new information about the condition of the vehicle electrical system is generated and thus additional measuring points are not required. Another advantage is that the DC / DC converter in addition to the actual

Power supply gets the task to determine the electrical system condition and thus gets an added value compared to competing products.

Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawings.

It is understood that the features mentioned above and those yet to be explained not only in the combination specified in each case, but also in other combinations or alone, without departing from the scope of the present invention.

Brief description of the drawings

FIG. 1 shows a vehicle electrical system.

FIG. 2 shows an embodiment of a vehicle electrical system.

FIG. 3 shows a further embodiment of a vehicle electrical system.

FIG. 4 shows an embodiment of a vehicle electrical system

FIG. 5 shows an embodiment of a vehicle electrical system.

Embodiments of the invention

The invention is schematically illustrated by means of embodiments in the drawings and will be described in detail below with reference to the drawings.

FIG. 1 shows a vehicle electrical system, which is provided overall with the reference numeral 10 and represents a two-channel vehicle electrical system according to the prior art.

The illustration shows a generator or an electric machine 12, which supplies a voltage of 48 V, a first so-called electronic power

Distribution unit 14 (electronic power supply unit; ePDU), a first consumer 16, a first battery 18, a first

Battery Management System (BMS) 20, a first DC-DC converter 22 that converts the voltage of 48V to a voltage of 14V, a second ePDU 24, a second load 26, a second battery 28 with a battery sensor 30, a second DC-DC converter 32, which converts the voltage of 48 V to a voltage of 14 V, a third battery 34 with a battery sensor 36, a safety-relevant consumer Rsla 38, whose function is redundantly satisfied by a consumer Rslb 40 . a safety-related consumer Rs2a 42 with an internal, redundant load Rs2b 44.

Figure 2 shows a simplified electrical system, which is provided with the reference numeral 200 and is also referred to as a subnet. The illustration shows a DC-DC

Transducer 202, an energy management system 204, a battery 206, a battery sensor 208, and a consumer Rsla 210. Further, a node K1 is designated by reference numeral 212. The DC / DC converter 202 feeds a current l_DcDc 220 as a current source into this subnetwork and supplies all the consumers, which here are represented simply by the consumer Rsla 210, with the current I_Consumer 222 and charges the battery 206 with a current I_Batt 224 So according to the first 1. Kirchoffoff law: l_Batt + l_Consumer = l_DcDc (1)

When the DC-DC converter 202 is turned off, i. H. l_DcDc = 0, the following applies: l_Consumer = l_Batt, (2) d. H. the battery current is reversed, the battery 206 supplies the entire vehicle electrical system 200. Thus, the current on-board network load can be determined via the battery sensor 208. If the drive signals of the consumers are known, the theoretical load load can be determined via this. For example, 100% control means that the rated current of the component must flow.

In a first embodiment of the presented method, for example, all consumers are turned off. This is also called active

Diagnostics, or alternatively wait until all consumers report that they are currently inactive. This is called a passive diagnosis

designated. It then applies: l_Consumer = 0 (3) If the DC-DC converter 202 is also switched off at this time, ie I_DCDC = 0, then l_EBS = 0 must apply in this case. I_EBS is illustrated by reference numeral 230.

If I_EBS O, either a) the current measured by the battery sensor 208 may be incorrect

or

b) Consumers can continue to be active.

To make it plausible, the DC-DC converter 202 is turned on. If the vehicle electrical system voltage is set to the value of the battery return voltage, the battery will not be charged. H. I_EBS = 0, and the DC / DC converter 202 only supplies the loads. If the consumers are still switched off, the following must apply: l_DCDC = l_Consumer = 0 (4)

If l_DCDC Φ 0, consumers are thus also unauthorized.

If l_DCDC = l_Consumer = 0 but l_EBS Φ 0, there is an error in the battery sensor 208 in this case.

According to the same scheme, in a second embodiment

proceed as shown in Figure 4, the one or more consumers of an electrical fuse (ePDU) is monitored.

Figure 3 shows a simplified electrical system, which is provided with the reference numeral 300 and is also referred to as a subnet. The illustration shows a DC-DC converter 302 as a coupling element, a power management system 304, a battery 306 as a power supply, a battery sensor 308, a

Consumers Rsla 310 as a component and an ePDU 314. Furthermore, a node Kl is designated by reference numeral 312. This also has the task to measure the current of the component in order to switch off, if necessary. It may also be turned off to test the ePDU 314 of the DCDC converter 302 here.

If l_DCDC (reference numeral 320) = 0, it can be checked whether: 1_EBS (reference numeral 322) = - 1_ePDU (reference numeral 324) (5)

If this test fails, the voltage of the DCDC converter 302 is again set to a value at which I_EBS = 0, d. H. U_EBS (reference numeral 326) is in the range of battery return voltage.

In this case it can be checked whether: l_DCDC = - l_ePDU (6) If this check also fails, it can be concluded that l_ePDU 324 is faulty, otherwise l_EBS 322 is faulty.

The l_EBS 322 stream can be validated by using the ePDU 314

Consumer disconnects from the electrical system 300.

If the battery 306 is now charged or the voltage of the DCDC converter 302 is set to a voltage above the gassing voltage of the battery 306 and l_DCDC is -1_EBS, it can be concluded that I_EBS 322 is being measured incorrectly.

In a third embodiment, two or more consumers are powered by the ePDU. Reference is made to FIG. 4. FIG. 4 shows a simplified vehicle electrical system, which is provided with the reference numeral 400 and is also referred to as a subnetwork. The illustration shows a DC-DC converter 402, an energy management system 404, a battery 406, a battery sensor 408, a consumer Rsla 410, an ePDU 414 and a consumer Rs2a 416. Furthermore, a node K1 is designated by reference numeral 412.

The diagnoses take place according to the scheme explained above, in particular the first embodiment. However, in order to allocate which consumer can not possibly be switched off, the consumers 410, 416 are deactivated one after the other and the current I_ePDU 424 or the source current is observed. The power does not change after a shutdown command, although a consumer turns off. or should be switched on, while all others

Consumers are disabled, it can be assumed that the consumer can not be separated. This indicates a defect.

The DC-DC converter can also be used to diagnose the wiring harness. By way of example, the electrical system topology shown in FIG. 6 is assumed.

FIG. 5 shows a simplified vehicle electrical system, which is provided with the reference numeral 500 and is also referred to as a subnetwork. The illustration shows a DC-DC converter 502, an energy management system 504, a consumer Rsla 510, a consumer Rs2a 516 and an ePDU 514.

Figure 5 shows a possible implementation of the invention in the very schematically illustrated on-board network 500. On the left side of the DC-DC converter 502 including a measuring resistor 550 is shown for a current measurement. For the sake of clarity, not shown is the voltage measurement. On the right side is also very simplistic two on-board network component shown, which consists among other things of the engine, control logic, switches and sensors. These represent consumers. This vehicle electrical system component can be, for example, the stability system ESP, the iBooster, the electric power steering or another component. Relevant is a switchable load that generates a current flow that differs significantly between passive and active operation

(eg> 10 A).

Also within this component there is a measurement of

Supply voltage to ground. Furthermore, the component current is measured. Again, this is already the case for some components today. In a variant of the invention can be dispensed with the measurement of the component current.

The second load is exemplarily monitored by an electronic fuse, the ePDU 514. In the presented method already existing, above-mentioned components are used.

If the component, z. B. the ESP, is in standby, d. H. the microcontroller is active without the motor being energized, the DC / DC converter 502 converts the converter output voltage U_DCDC and the converter current l_DCDC 520 as well as terminal voltage U_RSla / U_RSlb / U_ePDU and possibly the component current l_RSla in the component or in the ePDU l_ePDU measured.

The subsequent comparison takes place, for example, in the respective component by transferring the measured values from the DC-DC converter to the component. In an alternative solution, it is also possible to transmit to another control unit or to another onboard power supply component. The value pairs are finally saved.

As soon as the component is active, the same measured values are recorded. The component can either be activated for a self-test in which the harness is also tested by the illustrated method. On the other hand, it is also possible to wait until the component is active through use. It is important that a defined current flows over the component. Three cases are distinguished below: Case A)

For this purpose it is expedient to measure the component flow. From the two voltage measurements and the component current, the resistance in the wiring harness can be determined and checked with threshold values. However, it is expedient if the component is supplied only from the battery, since then the entire chain can be tested.

In a variant of the invention, a comparison with previous values which have been stored is expedient in order, if necessary, to note a continuous deterioration or to compare it with the reference to the new condition.

In a variant, the current measurement in the component can be dispensed with if it is determined on the basis of the change in the converter current I_DCDC. For this, the component must be supplied from the DC-DC converter and the change l_DCDC must be tracked simultaneously with the activation of the component. From the change of l_DCDC at input and output

Turning off the component may affect the current in the component

getting closed.

Case B)

In another embodiment, an electronic fuse included in the "electronic power distribution unit" is inserted in the wiring harness,

for example, instead of the backup box. In this embodiment, the ePDU is used to detect the component flow via appropriate measures.

Furthermore, the ePDU can be used to narrow the error by the method described above, in which the voltage is detected at the ePDU and compared both with the component voltage U_RE2a and with the converter output voltage U_DCDC.

Case C)

Especially with heaters, the resistance of the components is well known and defined. This resistance causes depending on Supply voltage, this is measured by the component, a current flow. This means that in these components with defined load resistance in a further embodiment, the current is determined by calculation.

About the respective voltage drops during and outside of the

Component control and the component current is then the harness resistance in the harness to the ePDU and component detected. To increase the robustness, the measurements mentioned can be carried out several times.

If the harness resistance exceeds a threshold, a

Error memory entry can be generated, a warning lamp can be turned on or safety-related functions such as automatic driving prohibited.

The described diagnoses can be carried out on the one hand during a driving cycle, for example on the one hand when the components are inactive and on the other hand when the components are active.

In a further embodiment, the diagnoses described can be carried out before a drive cycle or at the beginning of a drive cycle in order to actively test systems before the start of the journey. For this purpose, components are selectively controlled and, for example, supplied specifically from the battery.

In a further embodiment, the diagnoses can be carried out in a workshop, for example, in which the wire harness and the electrical stores are checked according to the invention at regular intervals.

This ensures that the electrical system of the vehicle is in proper condition for safety-relevant driving functions.

Claims

claims

1. A method for operating a vehicle electrical system (200, 300, 400, 500), the at least two channels with at least one component and a

Energy supply includes, with between the two channels

Coupling element is provided, wherein the coupling element is used to perform a diagnosis by at least one measurement is made in this,

2. The method of claim 1, wherein the first measurements are performed at a first power consumption of at least one of the at least one component and second measurements at a second power consumption of at least one of the at least one component and the first measurements and the second measurements are compared with each other and based it is determined whether the at least one of the at least one component works as intended.

3. The method of claim 1 or 2, wherein the at least one of the at least one component is switched on and off.

4. The method according to any one of claims 1 to 3, wherein the coupling element DC-DC converter (202, 302, 402, 502) is used.

5. The method according to any one of claims 1 to 4, wherein a current measurement is carried out in the coupling element.

6. The method according to any one of claims 1 to 5, wherein a

Voltage measurement is performed in the coupling element

7. The method according to any one of claims 1 to 6, wherein a diagnosis of a wiring harness of the electrical system (200, 300, 400, 500) is performed.

8. The method according to any one of claims 1 to 7, wherein a comparison with by a battery sensor (208, 308, 408) determined values is performed.

9. The method according to any one of claims 1 to 8, which is carried out at a restart of the electrical system (200, 300, 400, 500).

10. The method according to any one of claims 1 to 8, at the beginning of a

Driving cycle is performed.

11. The method according to any one of claims 1 to 10, by means of a

Computer program is performed.

12. vehicle electrical system, in particular for carrying out a method according to one of claims 1 to 11, the at least two channels with at least one

Component and includes a power supply, being between the two

Channels a coupling element is provided, wherein the electrical system (200, 300, 400, 500) is adapted to use the coupling element to perform a diagnosis by at least one measurement is made in this.

13. Vehicle electrical system according to claim 12, which is further configured to perform first measurements at a first current consumption of at least one of the at least one component and second measurements at a second current consumption of at least one of the at least one component and to compare the first measurements and the second measurements and determining whether the at least one of the at least one component operates as intended.

14. The electrical system according to claim 12 or 13, which has an energy management system (204, 304, 404, 504).