DE102021003180A1 - On-board electrical system for an electrically operated vehicle and method for operating an on-board electrical system - Google Patents

Abstract

The invention relates to an on-board electrical system (100) for an electrically operated vehicle, with at least one first and at least one second electrical potential line (HV +, HV-) DC voltage is applied, the on-board network (100) having at least two first interference suppression capacitors (Cy1, Cy2), in particular Y capacitors, which are electrically connected in series and each with a connection (10, 12) to the potential lines (HV +, HV -) are electrically coupled, and their common connection (M1) is electrically coupled to an electrical ground, the on-board network (100) having at least two further interference suppression capacitors (Cy3, Cy4), in particular Y capacitors, which are electrically connected in series and each having a connection (14, 16) with the potential lines (HV +, HV-) are electrically coupled, and their common connection (M2) via at least z Wei switch (T1, T2) is electrically coupled to the electrical ground. The invention also relates to a method for operating an on-board electrical system (100).

Description

The invention relates to an electrical system for an electrically operated vehicle and a method for operating an electrical system for an electrically operated vehicle.

Radio interference suppression capacitors are used to block and dampen interference signals on the power supply lines of devices, which are divided into classes X and Y depending on the requirement profile.

Class X capacitors are after IEC 60384-1 standard from 2016 electrical capacitors that are switched between phase and neutral conductor or between two phases. They can have any high capacity. They often have values from 100 nF to 1 µF.

Class Y capacitors according to the IEC 60384-1 standard from 2016 are capacitors that are connected between the phase or neutral conductor and touchable, protective earthed device housing and thus bridge the basic insulation. According to this standard, only those capacitors are permitted for Y capacitors that have a verifiable increased electrical and mechanical safety with a limited capacity, since if they are used in the event of a failure due to a short circuit, people or animals can be endangered by electric shock.

It is known that on-board electrical systems of electric vehicles and hybrid vehicles (passenger cars or commercial vehicles) are usually designed as direct voltage (DC direct current) with one or more poles. The electrical DC voltage poles are correspondingly electrically isolated and capacitively coupled to the vehicle ground via Y capacitances.

In the event of a fault, however, a person can discharge and recharge the energy stored in the Y capacitors. In the worst case, the discharge of stored energies through people can create an electrical hazard. For this reason, the energies of Y capacitances for a HV system are limited to the so-called C1 limit of IEC 60479-2. In addition, a limitation of the Y-capacitance is necessary for the function of the insulation monitoring in the vehicle as well as in the charging station.

the DE 10 2016 211 387 A1 discloses a charging device (e.g. charging cable, charging station or wallbox) for charging a partially electrically operated vehicle (e.g. electric vehicle, hybrid vehicle) which comprises an electrical component (e.g. ohmic resistor) and a switching device (e.g. opto triac, relay). One electrical component and the switching device are arranged in the charging device in such a way that when the charging device is connected to a vehicle, a circuit to support the discharge (e.g. in the form of a partial discharge) of a capacitor provided on the vehicle side results, which is opened by means of the switching device or closed (e.g. also switched on).

One object of the invention is to create an on-board electrical system for an electrically operable vehicle that ensures safe operation when driving and when transmitting electrical energy between a charging station and a vehicle, in particular during rapid charging.

Another object is to specify a method for operating such an on-board electrical system for an electrically operated vehicle.

The aforementioned objects are achieved with the features of the independent claims.

Favorable configurations and advantages of the invention emerge from the further claims, the description and the drawing.

According to one aspect of the invention, an on-board electrical system for an electrically operated vehicle is proposed, with at least one first and at least one second electrical potential line, the on-board network being subjected to an electrical direct voltage in normal operation between the potential lines, the first and the second Potential line is electrically coupled to a high-voltage energy store. The vehicle electrical system has at least two first interference suppression capacitors, in particular Y capacitors, which are electrically connected in series and are each electrically coupled to a terminal with the potential lines, and whose common terminal is electrically coupled to an electrical ground. The vehicle electrical system has at least two further interference suppression capacitors, in particular Y capacitors, which are electrically connected in series and are each electrically coupled to a terminal with the potential lines, and the common terminal of which is electrically coupled to the electrical ground via at least two switches.

The capacity of interference suppression capacitors, in particular Y- Capacitors, can be limited in that capacitors can be switched off during the charging process.

Any disadvantages that may arise with regard to electromagnetic compatibility can be avoided by only temporarily disconnecting the capacitors during the charging process. When driving, however, the capacitors can be switched on again as required.

According to the invention, the first interference suppression capacitors are permanently installed with respect to the ground, for example the vehicle chassis, and can, for example, have capacities of 20 nF each in order to limit the maximum stored energy when charging with 800 V, for example.

The additional interference suppression capacitors can, for example, have capacities of 80 nF and be separated from ground by switches during charging.

While driving, the other capacitors are connected to the ground again and act as normal interference suppression capacitors.

In this way, the total capacity of the vehicle electrical system and thus the energy stored in the interference suppression capacitors during the charging process can advantageously be limited.

According to an advantageous embodiment of the electrical system, the common connection of the two first interference suppression capacitors and the common connection of the two further interference suppression capacitors can be electrically coupled via a resistor. In particular, the resistance can be greater than 100 kOhm. In the event of an external insulation fault, the maximum discharge current of the two additional interference suppression capacitors can be greatly reduced by the resistor and the risk of damage can be reduced. If the resistance is greater than 100 kOhm, a high voltage test can be carried out without additional supply voltages or other measures.

According to an advantageous embodiment of the electrical system, the two switches can be designed as oppositely connected transistors, in particular MOSFET transistors. In this way, the two additional interference suppression capacitors can advantageously be disconnected from ground by means of bidirectional blocking, for example during an 800 V charging process.

According to an advantageous embodiment of the electrical system, a drain connection of one switch of the two switches can be electrically coupled to the common connection of the two first interference suppression capacitors and a drain connection of the other switch can be electrically coupled to the common connection of the two further interference suppression capacitors. Source connections of the two switches can each be electrically coupled to one another. With such an interconnection, two MOSFET transistors can advantageously be used as switches in a bidirectional blocking arrangement. The two switches can be controlled appropriately via the corresponding source connections of the two MOSFET transistors, so that the two additional interference suppression capacitors can advantageously be switched off from ground by means of bidirectional blocking during an 800 V charging process.

According to a further aspect of the invention, a method for operating an on-board electrical system for an electrically operable vehicle is proposed, with at least a first and a second electrical potential line, the on-board network being designed to have an electrical direct voltage applied between the potential lines during normal operation be, wherein the first and the second potential line is electrically coupled to a high-voltage energy store. The vehicle electrical system has at least two first interference suppression capacitors, in particular Y capacitors, which are electrically connected in series and are each electrically coupled to a terminal with the potential lines, and whose common terminal is electrically coupled to an electrical ground. The vehicle electrical system has at least two further interference suppression capacitors, in particular Y capacitors, which are electrically connected in series and are each electrically coupled to a terminal with the potential lines, and the common terminal of which is electrically coupled to the electrical ground via at least two switches. The two switches are opened when the high-voltage energy storage device is charged.

In this way, the capacity of interference suppression capacitors, in particular Y capacitors, can advantageously be limited during fast charging, in particular during direct current charging with high charging powers of, for example, 300 kW at 800 V, in that capacitors can be switched off during the charging process.

Any disadvantages that may arise with regard to electromagnetic compatibility can be avoided by only temporarily disconnecting the capacitors during the charging process. When driving, the Capacitors, on the other hand, can be switched on again as required.

According to the invention, the first interference suppression capacitors are permanently installed with respect to the ground, for example the vehicle chassis, and can, for example, have capacities of 20 nF each in order to limit the maximum stored energy when charging with 800 V, for example.

The additional interference suppression capacitors can, for example, have capacities of 80 nF and be separated from ground by switches during charging.

While driving, the other capacitors are connected to the ground again and act as normal interference suppression capacitors.

In this way, the total capacity of the vehicle electrical system and thus the energy stored in the interference suppression capacitors during the charging process can advantageously be limited.

According to an advantageous embodiment of the method, the two switches can be closed at least when the vehicle is in motion. This ensures that the requirements for electromagnetic compatibility (EMC requirements) of the electrically operated vehicle are met when driving.

According to an advantageous embodiment of the method, the common connection of the two first interference suppression capacitors and the common connection of the two further interference suppression capacitors can be electrically coupled via a resistor. In particular, the resistance can be greater than 100 kOhm. A high voltage test can be carried out across the resistor. In the event of an external insulation fault, the maximum discharge current of the two additional interference suppression capacitors can be greatly reduced by the resistor and the risk of damage can be reduced. If the resistance is greater than 100 kOhm, a high voltage test can be carried out without additional supply voltages or other measures.

According to an advantageous embodiment of the method, a voltage increase and / or current increase during the high-voltage test can be limited in order to limit a maximum voltage across the two switches, in particular to below 1200V. In this way, a required high-voltage test of the vehicle's electrical system can be carried out in an advantageous and safe manner.

According to an advantageous embodiment of the method, a state of the two switches can be determined by measuring a voltage between the common connection of the two first interference suppression capacitors and the common connection of the two further interference suppression capacitors. In this way, it can advantageously be determined whether the two switches are closed or open, that is to say whether the two further interference suppression capacitors are connected to ground or switched away from ground. In the case of open switches, a voltage change is expected, since insulation monitoring will continuously charge the entire Y-capacitance of the high-voltage on-board electrical system. When both switches are closed, the voltage change drops to zero volts because of the low internal resistance of MOSFET switches.

Further advantages emerge from the following description of the drawings. An exemplary embodiment of the invention is shown in the drawing. The drawing, the description and the claims contain numerous features in combination. The person skilled in the art will expediently also consider the features individually and combine them into meaningful further combinations.

• 1 eine Systemübersicht eines Teils eines elektrischen Bordnetzes für ein elektrisch betreibbares Fahrzeug nach einem Ausführungsbeispiel der Erfindung.

It shows:

• 1 a system overview of part of an on-board electrical system for an electrically operated vehicle according to an embodiment of the invention.

In the figure, the same or similar components are numbered with the same reference numerals. The figure shows only examples and is not to be understood as restrictive.

1 shows a system overview of part of an on-board electrical system 100 for an electrically operated vehicle according to an embodiment of the invention.

The electrical system 100 has a first and a second electrical potential line HV + , HV- on. The vehicle electrical system is in normal operation 100 between the potential lines HV + , HV- applied with an electrical direct voltage by the first and the second potential line HV + , HV- at the connections 10 , 12th is electrically coupled to a high-voltage energy store.

The on-board network 100 has two first interference suppression capacitors Cy1 , Cy2 , in particular Y capacitors, which are electrically connected in series and each with a connection 10 , 12th with the potential lines HV + , HV- are electrically coupled. The common connection M1 of the first two suppression capacitors Cy1 , Cy2 is electrically coupled to an electrical ground.

The first interference suppression capacitors Cy1 , Cy2 are permanently installed according to the invention with respect to the mass, for example the vehicle chassis, and can, for example, have capacities of 20 nF each in order to limit the maximum stored energy when charging with 800 V, for example.

The on-board network 100 has two more interference suppression capacitors Cy3 , Cy4 , in particular Y capacitors, which are electrically connected in series and each with a connection 14th , 16 also with the potential lines HV + , HV- are electrically coupled. The common connection M2 of the two other interference suppression capacitors Cy3 , Cy4 is about two switches T1 , T2 with the electrical ground at the point M1 electrically coupled.

The other interference suppression capacitors Cy3 , Cy4 can for example have capacities of 80 nF and during charging from ground through the switches T1 , T2 be separated.

The connections 14th , 16 can for example be electrically connected to the power electronics of an electric motor, which is indicated by the dashed arrows.

The common connection M1 of the first two suppression capacitors Cy1 , Cy2 and the common connection M2 of the two other interference suppression capacitors Cy3 , Cy4 are about a resistance R. electrically coupled, which can advantageously be greater than 100 kOhm. In the event of an external insulation fault, the maximum discharge current of the two additional interference suppression capacitors can be used Cy3 , Cy4 through the resistance R. can be greatly reduced and so cannot cause any damage. When the resistance R. is greater than 100 kOhm, a high-voltage test can be carried out without additional supply voltages.

The two switches T1 , T2 are designed as oppositely connected MOSFET transistors. In this way, the two other interference suppression capacitors Cy3 , Cy4 for example, during an 800 V charging process, it can be advantageously switched away from ground by means of bidirectional blocking.

The drain connection D. of the switch T1 is with the common port M1 of the first two suppression capacitors Cy1 , Cy2 and the drain connection D. the other switch T2 is with the common connection ( M2 ) of the two other interference suppression capacitors Cy3 , Cy4 electrically coupled. The source connectors S. of the two switches T1 , T2 are each electrically coupled to one another.

With such an interconnection, two MOSFET transistors can advantageously be used as switches T1 , T2 can be used in a bidirectional blocking arrangement. The two switches T1 , T2 can via the corresponding source connections S. of the two MOSFET transistors are suitably controlled, so that the two other interference suppression capacitors Cy3 , Cy4 during an 800 V charging process can be advantageously switched away from ground by means of bidirectional blocking.

According to the invention, when charging the high-voltage energy store, the two switches T1 , T2 be opened.

In this way, the capacitance of the interference suppression capacitors, in particular the Y capacitors, can advantageously be limited during rapid charging, in particular during direct current charging with high charging powers of, for example, 300 kW at 800 V, by adding the capacitors Cy3 , Cy4 switched off during the charging process.

Any disadvantages that may arise with regard to electromagnetic compatibility (EMC requirements) can be avoided by only temporarily disconnecting the capacitors Cy3 , Cy4 be bypassed during the charging process. The capacitors Cy1 , Cy2 that are permanently installed always form the basic filtering that is necessary when charging with 800 V. When driving, the capacitors Cy3 , Cy4 on the other hand, can be switched on again as required.

The other capacitors are in place while driving Cy3 , Cy4 connected to ground again and act as normal interference suppression capacitors.

In this way, the total capacity of the on-board network and thus that of the interference suppression capacitors during the charging process Cy1 , Cy2 , Cy3 , Cy4 stored energy are advantageously limited.

At least when the vehicle is in motion, the two switches T1 , T2 are closed to allow the function of the two additional interference suppression capacitors Cy3 , Cy4 with regard to the electromagnetic compatibility of the vehicle. In this way, the requirements for electromagnetic compatibility (EMC requirements) of the electrically operated vehicle can be met when driving.

A voltage ramp and / or amount of current is limited in the high voltage test to a maximum voltage across the two switches T1 , T2 , especially below 1200 V. A necessary high-voltage test of the on-board electrical system can be carried out 100 of the vehicle can be carried out in an advantageous and safe manner.

A state of the two switches T1 , T2 can by measuring a voltage between the common terminal M1 of the first two suppression capacitors Cy1 , Cy2 and the common connection M2 of the two other interference suppression capacitors Cy3 , Cy4 to be determined.

In this way it can be advantageously determined whether the two switches T1 , T2 are closed or open, i.e. whether the two other interference suppression capacitors Cy3 , Cy4 connected to ground or disconnected from ground. In the case of open switches T1 , T2 a voltage change is expected because an insulation monitoring unit takes over the entire Y-capacity of the high-voltage electrical system 100 will load continuously. When both switches T1 , T2 are closed, the voltage change drops to zero volts due to the low internal resistance of MOSFET switches.

List of reference symbols

10

connection

12th

connection

14th

connection

16

connection

100

Electrical system

HV +

Potential line

HV-

Potential line

M1

common connection

M2

common connection

Cy1

Interference suppression capacitor

Cy2

Interference suppression capacitor

Cy3

Interference suppression capacitor

Cy4

Interference suppression capacitor

T1

counter

T2

counter

S.

Source

G

Gate

D.

Drain

R.

resistance

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was 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.

Patent literature cited

• DE 102016211387 A1 [0007]

Non-patent literature cited

• Standard IEC 60384-1 [0003, 0004]

Claims (9)

On-board electrical system (100) for an electrically operated vehicle, with at least one first and at least one second electrical potential line (HV +, HV-), the on-board network (100) in normal operation between the potential lines (HV +, HV-) with an electrical DC voltage is applied, the first and second potential lines (HV +, HV-) being electrically coupled to a high-voltage energy store, wherein the on-board network (100) has at least two first interference suppression capacitors (Cy1, Cy2), in particular Y capacitors, which are electrically connected in series and each electrically coupled to the potential lines (HV +, HV-) with a connection (10, 12) and their common connection (M1) is electrically coupled to an electrical ground, wherein the vehicle electrical system (100) has at least two further interference suppression capacitors (Cy3, Cy4), in particular Y capacitors, which are electrically connected in series and are each electrically coupled to the potential lines (HV +, HV-) with a connection (14, 16) and their common connection (M2) is electrically coupled to electrical ground via at least two switches (T1, T2). Electrical system according to Claim 1 , the common connection (M1) of the two first interference suppression capacitors (Cy1, Cy2) and the common connection (M2) of the two further interference suppression capacitors (Cy3, Cy4) being electrically coupled via a resistor (R), in particular where the resistor (R) is greater than 100 kOhm. Electrical system according to Claim 1 or 2 , wherein the two switches (T1, T2) are designed as oppositely connected transistors, in particular MOSFET transistors. Electrical system according to Claim 3 , wherein a drain connection (D) of a switch (T1) of the two switches (T1, T2) with the common connection (M1) of the two first interference suppression capacitors (Cy1, Cy2) and a drain connection (D) of the other switch ( T2) is electrically coupled to the common connection (M2) of the two further interference suppression capacitors (Cy3, Cy4) and source connections (S) of the two switches (T1, T2) are each electrically coupled to one another. A method for operating an on-board electrical system (100) for an electrically operable vehicle according to one of the preceding claims, with at least a first and a second electrical potential line (HV +, HV-), the on-board network (100) being designed to operate as intended between an electrical direct voltage is applied to the potential lines (HV +, HV-), the first and second potential lines (HV +, HV-) being electrically coupled to a high-voltage energy store, wherein the on-board network (100) has at least two first interference suppression capacitors (Cy1, Cy2), in particular Y capacitors, which are electrically connected in series and each electrically coupled to the potential lines (HV +, HV-) with a connection (10, 12) and their common connection (M1) is electrically coupled to an electrical ground, wherein the vehicle electrical system (100) has at least two further interference suppression capacitors (Cy3, Cy4), in particular Y capacitors, which are electrically connected in series and are each electrically coupled to the potential lines (HV +, HV-) with a connection (14, 16) and their common connection (M2) is electrically coupled to the electrical ground via at least two switches (T1, T2), the two switches (T1, T2) being opened when the high-voltage energy store is charged. Procedure according to Claim 5 , the two switches (T1, T2) being closed at least when the vehicle is in motion. Procedure according to Claim 5 or 6th , the common connection (M1) of the two first interference suppression capacitors (Cy1, Cy2) and the common connection (M2) of the two further interference suppression capacitors (Cy3, Cy4) being electrically coupled via a resistor (R), in particular where the resistor (R) is greater than 100 kOhm, with a high-voltage test being carried out across the resistor. Procedure according to Claim 7 , a voltage rise and / or current rise in the high voltage test being limited in order to limit a maximum voltage across the two switches (T1, T2), in particular to below 1200 V. Method according to one of the Claims 5 until 8th , a state of the two switches (T1, T2) being determined by measuring a voltage between the common connection (M1) of the two first interference suppression capacitors (Cy1, Cy2) and the common connection (M2) of the two further interference suppression capacitors (Cy3, Cy4) .

Images