DE102016005855A1 - High-voltage network for a motor vehicle with summation current-dependent charging interruption - Google Patents

Abstract

The invention relates to a high-voltage network (10) for a motor vehicle having a switching device (14) for electrically isolating a high-voltage battery (12) which can be connected to a DC voltage intermediate circuit of the high-voltage network (10), a control device (16) for controlling the switching device (14) and one for charging the high-voltage battery (12) to the DC voltage intermediate circuit of the high-voltage network (10) connectable charger, and a main load connected to the DC intermediate circuit (22). The control device (16) is designed, during a charging process, a charging current (I20) fed from the charging device (20) into the DC intermediate circuit, a battery current (I12) flowing from the DC intermediate circuit into the high-voltage battery (12) and one from the DC intermediate circuit in the main consumer flowing main current (I22) to determine, and in dependence on the difference between the charging current (I20) and a summation current, which is formed by the sum of at least the battery current (I12) and the main current (I22) to cancel the charging process. Furthermore, the invention relates to a method for operating such a high-voltage network (10) for a motor vehicle.

Description

The invention relates to a high-voltage network for a motor vehicle and to a method for operating a high-voltage network for a motor vehicle.

Motor vehicles, in particular electric vehicles or hybrid vehicles, may have a high-voltage network, which in particular serves to provide electrical energy for an electric drive. Under a high-voltage network in a vehicle, also referred to as high-voltage electrical system, is usually understood a vehicle electrical system with an operating voltage greater than 60 volts when operating with a DC voltage and greater than 30 volts when operating with an AC voltage. As energy storage for the electrical supply of the high-voltage network is a high-voltage battery, which is coupled via a switching device to the high-voltage network. Usually, this coupling is done via two so-called battery contactors, which allow a bipolar separation of the high-voltage battery from the high-voltage network. Thus, a reliable galvanic isolation possibility of the high-voltage network is provided by the feeding high-voltage battery, which allows, for example, in case of failure or in a maintenance case or even with a longer shutdown, to disconnect the high-voltage power.

For charging the high-voltage battery, an on-board on-board charger may be present, which is electrically coupled to the high-voltage electrical system, or it may be an external charger are used, which is coupled only as needed via a corresponding port with the high-voltage electrical system.

Damage, for example, a violation of a line, or a degradation of the isolation of a high-voltage network, for example due to water retention can lead to an undesirable parallel current, which can cause further progressive damage to the already pre-damaged component and possibly an overlap on other components.

From the US 2010/0237872 A1 For example, an apparatus and method for detecting leakage current of a battery are known. The device includes a floating capacitor charged with a voltage detected by a cathode terminal or an anode terminal of a battery, a cathode terminal selection switching unit for selecting a voltage detection path for the cathode terminal and charging the floating capacitor with a detection terminal of the cathode terminal, an anode terminal selection switching unit for selecting a voltage detection path for the anode terminal and charging the floating capacitor with a detection voltage of the anode terminal, a DC voltage application unit for applying a DC voltage through the voltage detection path for the anode terminal, a voltage measurement unit for measuring the charged detection voltage of the cathode terminal or anode terminal, and a A leakage current determining unit for determining the occurrence of a leakage current based on the measured detection peak tions of the cathode connection and anode connection.

It is an object of the present invention to provide a high-voltage network for a motor vehicle and a method for operating a high-voltage network for a motor vehicle, which enables simple protection means in the event of a fault current in the high-voltage network.

This object is achieved by a high-voltage network having the features of patent claim 1 and by a method having the features of patent claim 7. Advantageous developments of the present invention are the subject of the dependent claims.

The high-voltage network according to the invention for a motor vehicle comprises a switching device for the electrical activation of a connectable to a DC intermediate circuit of the high-voltage network high-voltage battery, a control device for driving the switching device and a charger for charging the high-voltage battery to the DC intermediate circuit of the high-voltage network charger and a Main consumers connected to the DC intermediate circuit. The control device is designed to determine during charging a charge current fed by the charger into the DC intermediate circuit, a battery current flowing from the DC intermediate circuit into the high-voltage battery and a main current flowing from the DC intermediate circuit into the main consumer, and depending on the difference between the charging current and a summation current, which is formed by the sum of at least the battery current and the main current to cancel the charging process.

The method proposes according to the invention for operating a high-voltage network for a motor vehicle: charging a connected to a DC intermediate circuit of the high-voltage network high-voltage battery in a charging process, determining a fed into the DC voltage intermediate charging current, one from the DC voltage intermediate circuit in the High-voltage battery flowing battery current and a flowing from the DC intermediate circuit in a main consumer main current, and canceling the charging operation in dependence on the difference between the charging current and a sum current, which is formed by the sum of at least the battery current and the main current.

This results in the advantage of a plausibility check of the charging current fed into the DC intermediate circuit of the high-voltage network with respect to the consumer currents taken from the DC intermediate circuit. On the basis of a balance analysis of the currents which are conducted via the DC voltage intermediate circuit of the high-voltage network, it can be determined in a particularly simple manner whether a parallel current flows at appreciable altitude within the high-voltage network, which does not flow from any of the components connected to the DC voltage intermediate circuit, ie , H. is detected neither by the charger nor by the high-voltage battery or by a consumer connected to the DC intermediate circuit. The provision of the individual currents flowing through the enumerated components to the control device can be realized in the motor vehicle particularly simply by transmitting the data of the current sensors already used in the respective components to the control device via a bus system, for example a CAN bus. Likewise, it is thus also possible to transmit a corresponding control specification from the control device to the switching device and the charger. By the invention, an improved protection of the high-voltage network (high-voltage drive system) of the main consumer and optionally operated on the DC intermediate circuit auxiliary consumers, the high-voltage battery, the charger and the driver and the other passengers can be achieved.

In a preferred development, the high-voltage network has at least one auxiliary consumer connected to the DC intermediate circuit, the total current being formed by the sum of the battery current, the main current and at least one secondary current flowing from the DC intermediate circuit into the secondary consumer. This has the advantage that even consumers with lower power, which take a much smaller current from the DC voltage intermediate circuit than, for example, the main consumer, can be included in the plausibility check. This is particularly important because, for example, a power electronics such as the drive converter during a charging usually shut down or has only a very low power consumption. On the other hand, additional secondary consumers operated on the DC voltage intermediate circuit can provide the predominant part of the load connected to the DC intermediate circuit with a significantly lower current drain compared to the current which the drive converter would remove from the DC intermediate circuit in a driving operation during the charging process. It is therefore of great importance that at least the secondary consumers with the highest power consumption are integrated into the plausibility check during the charging process.

In a particularly advantageous development, the total current is formed by the sum of the battery current, the main current and the secondary currents of all the auxiliary consumers connected to the DC voltage intermediate circuit. As a result, the greatest possible accuracy is achieved, so that ideally the sum of all taken from the DC link currents, the size of each of the high-voltage battery and the main consumer and the Nebenverbrauchern can be provided as an associated current reading, identical to that of the charger in the DC link fed charging current is. The difference in the form of a parasitically flowing parallel current thus results taking into account the corresponding accuracies of the respective current measured values.

In a further advantageous embodiment, the control device is designed to terminate the charging process when the difference exceeds a predeterminable value. In this case, the predefinable value is to be determined as a function of the available measuring accuracies and the degree of coverage of the possible consumers operated on the DC voltage intermediate circuit. In particular, the predefinable value must also be chosen with regard to the fact that a power converted to a defective component does not exceed a certain value.

In a further advantageous embodiment, the control device is designed to control the switching device for releasing the high-voltage battery when canceling the charging process. This makes it possible to disconnect the high-voltage grid voltage, so that further damage is reliably prevented.

Preferably, the high-voltage network may include a vehicle-side part of the charger, wherein the charger is designed for inductive energy transmission. This has the advantage that the vehicle-side part of the charger is permanently coupled to the high-voltage electrical network and thus possible errors such as in a defective or dirty plug connection omitted.

The advantages and features and embodiments described for the high-voltage network according to the invention apply equally to the method according to the invention and vice versa. Consequently, corresponding device features and vice versa can be provided for device features.

Further advantages, features and details of the invention will become apparent from the following description of a preferred embodiment and from the drawing. The features and feature combinations mentioned above in the description as well as the features and feature combinations mentioned below in the figure description and / or shown alone in the figure can be used not only in the respectively specified combination, but also in other combinations or in isolation, without the scope of To leave invention.

The single figure shows a simplified schematic representation of an embodiment of a high-voltage network according to the invention.

A DC voltage intermediate circuit of a high-voltage network 10 is with a high-voltage battery 12 via a switching device in the form of two high-voltage contactors 14 electrically coupled. Thus, the voltage across the DC link is equal to the voltage on the high voltage battery 12 if the two high-voltage contactors 14 are closed. For controlling the high-voltage contactors 14 is a control device 16 provided, which also still offers the opportunity to charge the high-voltage battery 12 to the DC voltage intermediate circuit of the high-voltage network 10 connectable charger 20 head for.

Furthermore, at the DC voltage intermediate circuit of the high-voltage network 10 as main consumer a drive converter 22 (Power electronics) connected. The drive converter 22 serves to control a drive machine 24 , Preferably, it is the prime mover 24 to a three-phase machine, in particular a three-phase asynchronous machine. Advantageously, a permanent-magnet-excited three-phase synchronous machine can be used. Furthermore, at the DC voltage intermediate circuit of the high-voltage network 10 a secondary consumer 26 as well as a secondary consumer 28 connected. At the secondary consumers 26 . 28 These may be, for example, high-voltage ancillary components such as HV-EKMV and HV-PTC.

A battery current I12 flows from the DC link to the high-voltage battery 12 , a charging current I20 flows out of the charger 20 in the DC voltage intermediate circuit. A main current I22 flows from the DC link to the drive converter 22 , a secondary current I26 flows from the DC voltage intermediate circuit in the secondary consumer 26 and a sidestream I28 flows from the DC voltage intermediate circuit in the secondary consumer 28 ,

Of course, any other number of secondary consumers can be operated on the DC link. Likewise, it may also be provided to operate more than one main consumer on the DC voltage intermediate circuit. The division between main consumer and secondary consumer is purely arbitrary and has no influence on the applicability of the invention.

In a high-voltage network, in particular a high-voltage drive train (high-voltage battery, power electronics, electric motor, DC / DC converter, high-voltage ancillary components such as HV-EKMV and HV-PTC) is usually no current plausibility instead, d. H. An electric current generated from the electric charger is not balanced. There is no summation of consumer electricity to the generator. Although the high-voltage battery has two protective mechanisms, contactors and high-voltage fuse. But is there a short-circuit current below the tripping characteristic of the charger, z. B. Short circuit in the power electronics or in the high-voltage wiring harness, so attacks no protection mechanism that separates the charger from the vehicle high-voltage train. Damage in the components or in the wiring harness is not prevented. This can lead to major damage, if the error was not detected and after charging the driving operation is recorded, can be greater damage on the power input of the high-voltage battery.

By means of a plausibility check of the currents in the high-voltage network according to the invention 10 , especially the high-voltage powertrain, can be a balancing of the electric current coming out of the charger 20 in the DC voltage intermediate circuit, in relation to the total current flowing in a main load (power electronics) and in the high-voltage battery, take place. Is z. As a short-circuit current in the power electronics, so the power consumption in power electronics is many times higher. There is an imbalance in the summation current consideration. In one as a control device 16 shown higher-level control unit, z. As a so-called "Common Powertrain Controller" (CPC) is detected that an imbalance is present, where a threshold is to define, and an action such as a charge stop the high-voltage battery via the charger initiated. At the same time, the driver can be informed, for example, about an operating and display concept, for example by means of a red warning lamp. In any case, but the charging process is immediately interrupted and stored an error, for example, in the engine control unit. The plausibility check of the current thus provides an additional protective function of the high-voltage network 10 ready. All the necessary information about the CAN bus is available to the "Common Powertrain Controller".

In the event that the difference between the charging current I20 and the summation current, formed from the battery current I12, the main consumer current I22, and the secondary currents I26 and I28, exceed a predetermined value, the charging process is aborted.

The embodiment is merely illustrative of the invention and is not limitative of it. Thus, of course, arrangements of consumers can be designed arbitrarily, without departing from the spirit of the invention.

Thus, it has been shown above how a summation current view can be used to protect the high voltage drive system including a high voltage charger or inductive charger.

LIST OF REFERENCE NUMBERS

10

High-voltage network

12

High-voltage battery

14

High-voltage contactor

16

control device

20

charger

22

Drive Converters

24

prime mover

26, 28

In addition to consumer

I12

Batteristrom

I20

charging current

I22

main power

I26, I28

sidestream

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 2010/0237872 A1 [0005]

Claims (7)

High-voltage network ( 10 ) for a motor vehicle characterized by - a switching device ( 14 ) for the electrical isolation of a DC voltage intermediate circuit of the high-voltage network ( 10 ) connectable high-voltage battery ( 12 ), - a control device ( 16 ) for controlling the switching device ( 14 ) and one for charging the high-voltage battery ( 12 ) to the DC intermediate circuit of the high-voltage network ( 10 ) connectable charger ( 20 ), and - a main consumer connected to the DC intermediate circuit ( 22 ), wherein - the control device ( 16 ) is designed to - during charging, one of the charger ( 20 ) in the DC intermediate circuit fed charging current (I20), one from the DC voltage intermediate circuit in the high-voltage battery ( 12 ), as well as a main current (I22) flowing from the DC intermediate circuit into the main consumer, and depending on the difference between the charging current (I20) and a summation current which is determined by the sum of at least the battery current (I12) and of the main current (I22) is formed to cancel the charging process. High-voltage network ( 10 ) according to claim 1, characterized in that the high-voltage network ( 10 ) at least one auxiliary consumer connected to the DC intermediate circuit ( 26 . 28 ), wherein the total current through the sum of the battery current (I12), the main current (I22) and at least one of the DC voltage intermediate circuit in the secondary consumer ( 26 . 28 ) flowing secondary stream (I26, I28) is formed. High-voltage network ( 10 ) according to claim 2, characterized in that the summation current through the sum of the battery current (I12), the main current (I22) and the secondary currents (I26, I28) of all connected to the DC intermediate circuit secondary consumers ( 26 . 28 ) is formed. High-voltage network ( 10 ) according to one of the preceding claims, characterized in that the control device ( 16 ) is designed to abort the charging process if the difference exceeds a predeterminable value. High-voltage network ( 10 ) according to one of the preceding claims, characterized in that the control device ( 16 ) is designed, when canceling the charging process, the switching device ( 14 ) for the activation of the high-voltage battery ( 12 ) head for. High-voltage network ( 10 ) according to one of the preceding claims, characterized in that the high-voltage network ( 10 ) a vehicle-side part of the charger ( 20 ), wherein the charger ( 20 ) is designed for inductive energy transmission. Method for operating a high-voltage network ( 10 ) for a motor vehicle characterized by - charging a DC voltage intermediate circuit of the high-voltage network ( 10 ) connected high-voltage battery ( 12 ) during a charging process, - determining a charging current fed into the DC intermediate circuit (I20), one of the DC voltage intermediate circuit in the high-voltage battery ( 12 ) flowing battery current (I12) and one of the DC voltage intermediate circuit in a main consumer flowing main current (I22), and - canceling the charging operation in dependence on the difference between the charging current (I20) and a summation current, which by the sum of at least the battery current (I12) and the main current (I22) is formed.

Images