DE102021114439A1 - Method for actively discharging a supply network of a motor vehicle - Google Patents

Abstract

A method (2) for actively discharging a supply network (13) of a motor vehicle (12), in particular a motor vehicle driven by an electric motor, is specified, the method (2) comprising the following steps: - providing a trigger signal (SA) for discharging by the Motor vehicle (12) on the basis of a triggering event;- Transmitting the triggering signal (SA) to a heating component (14) of the motor vehicle (12);- Starting the discharging of the supply network (13) as a function of the transmitted triggering signal (SA) by closing a switch ( 16), in particular an IGBT switch of the heating component (14), so that a discharge current (IE) is passed via a heating resistor (RH) of the heating component (14) for discharging;- ending the discharging after a predetermined time interval has elapsed and/or when it is reached a predetermined voltage level. A discharge device (18) and a motor vehicle (12) are also specified.

Description

The invention relates to a method for actively discharging a supply network of a motor vehicle and a discharging device and a vehicle.

In order to supply electrical components of a motor vehicle, it usually has an electrical supply network. Especially in the case of motor vehicles driven by electric motors, this has a high-voltage supply network in order to also supply one or more electric drive motors with electrical energy in addition to the typical electrical loads. The motor vehicle can thus be, for example, a fully electric motor vehicle or a motor vehicle designed as a hybrid vehicle. In the present case, the high-voltage supply network can be understood to mean a direct voltage supply network (DC network).

Such high-voltage supply networks, also simply referred to below as supply networks, have a high risk potential in the event of a failure and/or a dangerous situation. In particular, capacitors present within the supply network can discharge explosively in the event of an accident of the motor vehicle, which poses a danger both to the occupants and to the components that are still in the vehicle.

For this reason, especially in such an event, the supply network and especially the capacitors must be discharged to a predetermined voltage level within a specified or predetermined period of time in order to ensure adequate voltage protection.

The supply networks are currently being discharged passively or actively. A decentralized implementation of the passive discharge in each component leads to an increase in quiescent current consumption, which is associated with an increase in costs, since a separate discharge device must be present for each component connected to the supply network. Furthermore, demands on the discharge values, which are required by manufacturers and/or legal standards, are increasing. For example, there are specifications according to which, in the event of a fault (e.g. accident), a supply network must be discharged to a voltage level of less than 60V or generally to a voltage value in accordance with the extra-low voltage standard in less than four seconds.

Proceeding from this, the invention is based on the object of specifying a method and a discharge device and also a vehicle, via which active discharge of a supply network can be implemented easily, reliably and inexpensively.

With regard to the method, the object is achieved according to the invention by a method with the features of claim 1. With regard to the unloading device, the object is achieved according to the invention by an unloading device with the features of claim 8 and with regard to the motor vehicle, the object is achieved according to the invention by a motor vehicle with the features of claim 10.

Advantageous refinements, developments and variants are the subject matter of the dependent claims. The advantages and preferred configurations listed with regard to the method are to be transferred analogously to the unloading device and the motor vehicle and vice versa.

Specifically, the object directed to the method is achieved by a method for actively discharging a supply network of a motor vehicle. In particular, the motor vehicle is the motor vehicle already mentioned above, which is driven by an electric motor and which can specifically have a high-voltage supply network, also described above, with a voltage of up to 400V. The value of 400V is only to be understood as an example value and not as a limiting value. Furthermore, higher or lower voltage values are also conceivable. The active discharge therefore refers to the discharge of this high-voltage supply network.

In a first step, a triggering signal for discharging by the motor vehicle is provided on the basis of a triggering event. In this context, the triggering event can generally be understood as a fault and specifically either an accident of the motor vehicle or a so-called shutdown process. In the present case, the shutdown process of the vehicle can be understood to mean, for example, a process in which the motor vehicle is switched off, in which all electrical consumers of the motor vehicle are switched off apart from a few essential components. Thus, the unloading according to the invention does not only take place in the event of an accident.

In a second step, the triggering signal is transmitted to a heating component of the motor vehicle. In this case, the heating component of the motor vehicle can be understood to mean a heater and/or a heater of the motor vehicle. Such a heater and/or a heater is usually already present in the motor vehicle, so that in the present case no separate structural unit has to be installed in the motor vehicle.

The discharging of the supply network is then started depending on the transmitted trigger signal. For this purpose, a power switch, in particular an IGBT switch, of the heating component is closed, so that a discharge current is passed through a heating resistor for discharging. For example, the power switch can also be a MOSFET. By conducting the discharge current from the supply network via the heating resistor, the energy present in the supply network is thus converted into heat energy and the supply network is thus reliably discharged. In the present case, the heating resistor can generally be understood to mean an ohmic resistance and, for example, a heating layer resistor or a heating wire of the heating component.

In the last step, the discharging is terminated after a predetermined time interval has elapsed and/or when a predetermined voltage level of the supply network has been reached. In this case, the discharging process is preferably ended by opening the circuit breaker already mentioned. This step is based on the idea of complying with the conditions already mentioned at the outset with regard to a maximum discharge time for reaching a predetermined voltage level.

The above mentioned method offers advantages compared to the conventional discharge methods for utility grids. On the one hand, the already mentioned high power consumption of the vehicle is reduced, which at the same time results in the overall costs of the vehicle being minimized. Furthermore, the process allows the individual components to be designed for a maximum permitted discharge rate of less than 60V within 120 seconds. This brief discharge is actively taken over by the heating component. Furthermore, as a result, the entire supply network and not just parts or individual consumers of the supply network are discharged by one of the components. Furthermore, with the method described above, discharge powers with a value in the range of >0 kW up to a maximum discharge power that can be realized for such applications can also be made possible.

A main advantage of the method described is that no separate discharge circuit and therefore no separate modular structure is necessary. Rather, a component already installed in the motor vehicle, here the heating component, is used for active discharging in the manner of dual use. In this configuration, no separate protection against deformation is necessary for the discharge component either, since the housing of the heating component assumes this function in the present case.

In one embodiment, the method further includes increasing a maximum heating temperature of the heating component during discharging. This embodiment or this method step is based on the idea that the current technical limits of a maximum discharge power can be increased by temporarily increasing or deactivating protective limits implemented in the vehicle, such as a maximum heating temperature of the heating component. This ensures a greater discharge capacity of the heating component. In other words, the heating component is allowed to heat more during discharging than is implemented in normal operation for protection reasons. In this case, no error or warning message is issued.

In another embodiment, the method includes the step of increasing a maximum coolant temperature during discharging. In this context, the term “coolant” can generally be understood to mean a cooling medium, for example air or water, which is used for cooling. A combination of water and air cooling can also fall under this term. In other words, during discharging by the heating component z. B. coolant temperatures of up to 115 ° C for cooling the motor vehicle and / or the components allowed without an error or warning message is issued. As a result, the discharge capacity can also be increased. Furthermore, a repetition rate for the active discharging by means of the heating component can also be adjusted as a function of a period of use within a time interval.

In one embodiment, the maximum heating temperature or the maximum coolant temperature during discharging is increased for a predetermined time. On the one hand, this time interval is sufficient to achieve and ensure effective discharge performance within the prescribed conditions. However, this time interval is not so long that the increased heating temperature and/or the increased coolant temperature causes damage to the motor vehicle.

Furthermore, in a further embodiment, the method comprises the step that the heating component controls the discharging process. Thus, for example, sensors arranged within the heating component or Control units control the discharging process. This has the advantage, in particular, that the components and elements that are usually integrated and designed for controlling the heating process, which is used for the discharging process or for discharging, are used and no separate components have to be installed here.

According to one embodiment, the method also includes the step that the heating component also monitors the discharging process. In this context, monitoring can be understood to mean that, in particular, a time interval monitoring or a monitoring of the discharge current and/or a monitoring of the current voltage level of the supply network takes place in order to control the discharging or to initiate the termination of the discharging process.

According to one embodiment, the control signal is transmitted to the heating component via a LIN/CAN bus of the motor vehicle. This advantageously means that no separate control for the heating component is necessary.

Specifically, the object directed to the discharge device is achieved by a discharge device for actively discharging a supply network of a motor vehicle, in particular a motor vehicle driven by an electric motor. In this case, the discharging device has a discharging unit with a power switch, in particular an IGBT switch, the discharging unit being set up in such a way as to close the power switch as a function of a trigger signal transmitted by the vehicle and thus to conduct a discharging current via a heating resistor of the heating component for discharging. In the simplest configuration, the unloading unit corresponds to the unloading device. In an alternative embodiment, the unloading device can, in addition to the unloading unit, also have other components that are not specified here, so that the unloading unit is part of the unloading device.

In one embodiment, the discharge unit is a heating component of the motor vehicle.

Specifically, the object directed to the motor vehicle is achieved by a motor vehicle with an unloading device. The unloading device can preferably be the unloading device described above. The motor vehicle is designed in cooperation with the unloading device in such a way that the methods described above can be carried out.

• 1 ein Blockschaltbild des erfindungsgemäßen Verfahrens sowie
• 2 eine skizzierte Darstellung eines Kraftfahrzeuges, das zur Durchführung des erfindungsgemäßen Verfahrens eingerichtet ist.

An embodiment of the invention is explained in more detail below with reference to the figures. These show in partly greatly simplified representations:

• 1 a block diagram of the method according to the invention and
• 2 a sketched representation of a motor vehicle which is set up for carrying out the method according to the invention.

Components with the same effect are always shown with the same reference symbols in the figures.

1 shows a sketched block diagram representation of the method 2 according to the invention for actively discharging a supply network 13 of a motor vehicle 12 (cf. 2 ).

Here, in a first step 4, a trigger signal S _A is provided. The basis for providing the triggering signal S _A is a triggering event, such as locking or parking vehicle 12 and/or an accident.

In the next step 6, the triggering signal S _A is transmitted to a heating component 14 (cf. 2 ) of the motor vehicle 12.

The discharging of the supply network 13 is then started 8 as a function of the transmitted trigger signal S _A by closing a circuit breaker 16, in particular an IGBT switch of the heating component 14 (cf. 2 ). Closing power switch 16 causes a discharge current I _E to flow through a heating resistor R _H of heating component 14.

This heats up the heating component 14 for discharging the supply network 13, since the energy to be discharged within the supply network 13 is converted into thermal energy in the heating resistor R _H .

In the last step 10, the discharging is terminated after a predetermined time interval has elapsed and/or when a predetermined voltage level is reached.

In 2 a motor vehicle 12 is shown schematically in the form of a rectangle, which has an unloading device 18 with an unloading unit 19 . In particular, the discharge unit 19 is not a separate device which is used separately for discharging the supply network 13 (which is also only shown in the form of a rectangle). Rather, components already located in the motor vehicle 12 are part of the unloading unit 19.

Thus, for example, the triggering signal S _A is transmitted by the vehicle 12 at for example, by a control unit 20 of the motor vehicle 12. As already mentioned, a circuit breaker 16, which is likewise only shown in simplified form, is then closed on the basis of the transmitted triggering signal S _A . The power switch 16 is in particular an IGBT switch.

The closed circuit breaker 16 creates an electrically conductive connection between the supply network 13 and the heating component 14 , so that the discharge current I _E flows through the heating resistor R _H of the heating component 14 , for discharging the supply network 13 .

A separate discharge circuit designed only for discharging the supply network 13 can thus be dispensed with. Rather, components that are already present in the motor vehicle 12 are designed accordingly and operated in a dual function (here specifically the heating component 14), so that components and costs can be saved on the one hand.

The invention is not limited to the exemplary embodiments described above. On the contrary, other variants of the invention can also be derived from this by a person skilled in the art without departing from the subject matter of the invention. The method described above can therefore also be used, for example and as an alternative, in the field of solar technology and here specifically in solar buffer storage tanks. In particular, all of the individual features described in connection with the exemplary embodiments can also be combined with one another in other ways without departing from the subject matter of the invention.

Reference List

2

procedure

4

Providing the trigger signal

6

Transmission of the trigger signal

8th

Start unloading

10

end of unloading

12

motor vehicle

13

supply network

14

heating component

16

circuit breaker

18

unloading device

19

unloading unit

20

control unit

SA

trigger signal

ie

discharge current

RH

heating resistor

Claims (10)

Method (2) for actively discharging a supply network (13) of a motor vehicle (12), in particular a motor vehicle driven by an electric motor, the method (2) comprising the following steps: - providing a trigger signal (S _A ) for discharging by the motor vehicle (12 ) based on a triggering event; - Transmitting the trigger signal (S _A ) to a heating component (14) of the motor vehicle (12); - Start discharging the supply network (13) depending on the transmitted trigger signal (S _A ) by closing a circuit breaker (16), in particular an IGBT switch of the heating component (14), so that a discharge current (I _E ) via a heating resistor ( R _H ) of the heating component (14); - Termination of discharging after a predetermined time interval and / or when a predetermined voltage level is reached. Method (2) according to claim 1 , further comprising the step of: - increasing a maximum heating temperature of the heating component during discharging. Method (2) according to one of Claims 1 or 2 , further comprising the step of: - increasing a maximum coolant temperature during discharging. Method (2) according to one of claims 2 or 3 , characterized in that the maximum heating temperature or the maximum coolant temperature during discharging is increased for a predetermined time. Method (2) according to any one of the preceding claims, further comprising the step of: - Control of the discharge process by the heating component (14). Method (2) according to any one of the preceding claims, further comprising the step of: - Monitoring the discharge process by the heating component (14). Method (2) according to one of the preceding claims, characterized in that the control signal is transmitted via a LIN/CAN bus of the motor vehicle. Discharge device (18) for the active discharge of a supply network (13) of a motor vehicle (12), in particular one driven by an electric motor Benen motor vehicle, characterized by a discharge unit (19) with a power switch (16), in particular an IGBT switch, the discharge unit (19) being set up in such a way as a function of a triggering signal (S _A ) transmitted by the motor vehicle (12). To close circuit breaker (16) and thus to conduct a discharge current (I _E ) via a heating resistor (R _H ) of the heating component (14) for discharging. Unloading device (18) after claim 8 , characterized in that the discharge unit (19) is a heating component (14) of the motor vehicle (12). Motor vehicle (12) with an unloading device (18) according to one of Claims 8 or 9 .

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