Electric vehicle and method for operating the same

Abstract

Electric vehicle (1), - with a high-voltage battery (2) for supplying power to an electric drive device (4), - with a 12V battery (5), marked by - a cooling device (6) for cooling the high-voltage battery (2) with a cooling circuit (7) in which the high-voltage battery (2) is integrated, a cooler (9), a fan (10) arranged in the area of ​​the cooler (9) and a coolant pump (8), - a DC / DC converter (11), via which the coolant pump (8) and the fan (10) are connected to the high-voltage battery (2) for driving in normal operation, - a thermal management module (12) which is designed such that, in the event of a fault in the high-voltage battery (2), it connects the coolant pump (8) and the fan (10) for driving the same to the 12V battery (5) and completely interrupts the electrical connection of the high-voltage battery (2) to all other components (14), thereby electrically isolating the high-voltage battery (2).

Description

The present invention relates to an electric vehicle. The invention also relates to a method for operating such an electric vehicle.US 2021 / 0 206 275 A1 discloses a generic electric vehicle having a high-voltage battery for supplying voltage to an electric drive device and a 12V battery.WO 2021 / 062 305 A1 discloses a system which switches over to a secondary battery in the event of a fault in a main battery.U.S. Pat. No. 11 407 280 B1 discloses a heating system for an electric vehicle, comprising a circuit for operating a switching device in an intermediate state between a fully switched-off state and a fully switched-on state, in which the heating system generates heating heat. The circuit can also operate the switching device in a fully switched-off state and a fully switched-on state and a second state in such a way that it cycles through the first intermediate state and the second state and thereby both drives the electric vehicle and heats it.From EP 4 140 802 A1 a method for charging and heating a vehicle battery of an electric vehicle using a battery charger of the electric vehicle is known, wherein the battery charger can heat the battery without charging it simultaneously. Once the temperature of the battery is sufficiently high for an optimal charging operation, the battery charger charges the battery. This is intended to make it possible to charge the battery in a temperature window that is optimum for a charging process.DE 10 2022 200 344 A1 discloses a battery having a first battery cell arrangement and a second battery cell arrangement, each of which has at least one battery cell, a first and a second switch and an evaluation unit, wherein in each battery cell arrangement the respective first switch is connected in series with the battery cell of the battery cell arrangement and the respective second switch is connected in parallel with the series circuit of the battery cell and its associated first switch. The individual battery cell arrangements are connected in series. The evaluation unit controls the switches of a respective battery cell arrangement independently of the switches of respective other battery cell arrangements. Furthermore, the evaluation unit is designed to actuate the first switch of a respective battery cell arrangement for closing and the second switch of the respective battery cell arrangement for opening, in order to actively use the at least one battery cell of the respective battery cell arrangement within the battery and to actuate the first switch of a respective battery cell arrangement for opening and the second switch for closing, in order to bridge the at least one battery cell in series connection from the battery cell arrangements. This is intended to allow all battery cell arrangements of the battery to be individually added to or separated from a battery cell arrangement assembly forming the battery.US 2022 / 0 149 454 A1 discloses a method for thermal monitoring in a battery cooling system, in which a power for operating a cooler is maintained even if an event of a battery cell disables the latter. The cooler is thereby able to prevent the thermal propagation from the cell in question to adjacent cells.From US 2021 / 0 129 915 A1 a platform for replacing an engine assembly with a frame is known.DE 10 2021 132 034 A1 discloses a cooling arrangement for cooling a battery of a motor vehicle, having a coolant circuit which comprises a cooling device through which a coolant can flow. The cooling device is in this case capable of absorbing heat released by the battery during operation of the battery. The coolant circuit has an outlet via which the coolant can be supplied to a cooling module external to a vehicle, and an inlet via which the coolant can be introduced into a section of the coolant circuit in the vehicle.Generally, a cooling requirement in battery-electric vehicles, in particular electric vehicles, increases steadily due to an increasing number of power functions, higher computer powers, etc., which in turn requires large and powerful cooling systems, in particular immersion-cooled systems with dielectric coolant. For the constantly increasing number of components to be cooled and the cooling requirement which increases as well as the viscosity and further fluid-mechanical properties of the dielectric cooling media, the power requirement also increases in order to be able to supply the cooling systems, in particular a coolant pump, a compressor and / or a fan, with electrical energy. Since in electric vehicles a 12 volt power is limited by the power capability of central DC / DC converters, high-power units, in particular in the region of the cooling system, for example coolant pumps, are typically drawn to other voltage levels, so that these are supplied with electrical energy, for example, by a high-voltage battery of the electric vehicle in normal operation.However, this involves a risk that is not underestimated, since in the case of a so-called thermal runaway of a battery cell of the high-voltage battery, the entire high-voltage battery fails and, as a result, further cooling thereof can no longer take place. Cooling which fails in this case, i.e. in the event of a fault, owing to the thermal runaway of a battery cell could lead to the high-voltage battery being ignited, which must necessarily be avoided.The present invention is therefore concerned with the problem of specifying an improved or at least one alternative embodiment for an electric vehicle, by means of which embodiment in particular the disadvantages known from the prior art can be at least reduced, preferably even avoided.This problem is solved according to the invention by the subject matter of independent claim 1. Advantageous embodiments are the subject matter of the dependent claim.The present invention is based on the general idea of providing, in an electric vehicle known per se, a thermal management module having a high-voltage battery for supplying voltage to an electric drive device, a 12V battery for supplying voltage to other electrical components and a cooling device for cooling at least the high-voltage battery, which thermal management module, in the event of a battery cell of the high-voltage battery passing thermally, switches the voltage supply of the cooling device from the high-voltage battery to the 12V battery, with the result that said battery continues to be operated even in the event of failure of the high-voltage battery and can furthermore cool the high-voltage battery, with the result that the risk of the high-voltage battery being ignited can be significantly reduced, preferably even avoided. The cooling device of the electric vehicle according to the invention serves in particular for cooling the high-voltage battery, but can also cool further components or be part of an air-conditioning system. The cooling device has a cooling circuit in which the high-voltage battery is incorporated, a cooler and a coolant pump. Furthermore, a so-called DC / DC converter is provided, via which the coolant pump is connected to the high-voltage battery for driving in normal operation. The DC / DC converter converts the voltage provided by the high-voltage battery, for example 400 V, to 12 V, so that the 12 V coolant pump can be supplied with electrical energy by the high-voltage battery during normal operation. The thermal management module provided according to the invention is now designed in such a way that, in the event of a fault in the high-voltage battery, i.e. caused, for example, by a battery cell of the high-voltage battery undergoing thermal runaway, it connects the coolant pump to the 12V battery of the electric vehicle in an electrically conductive manner in order to drive the same, and as a result maintains the cooling operation, in particular for cooling the high-voltage battery, even in the event of failure of the high-voltage battery. On account of the thermal management module according to the invention, at least the coolant pump therefore has a redundant voltage supply, wherein the thermal management module can additionally also be designed for regulating the cooling of the high-voltage battery. The electric vehicle according to the invention thus offers the great advantage of continuing to maintain the cooling of the high-voltage battery via the 12V battery of the electric vehicle in the event of a fault, in particular in the event of a thermal runaway of a battery cell of the high-voltage battery and, for example, a failure of the high-voltage battery, and thereby reliably avoiding a breakdown of the high-voltage battery, i.e. a thermal runaway of further battery cells of the high-voltage battery. As a result, in particular the damage to the high-voltage battery or to the electric vehicle can be limited and the safety of vehicle occupants can be significantly increased.According to the invention, the cooling device has a fan in the region of the cooler. Such a fan is driven by an electric motor and conveys air through a heat exchanger block, in which dielectric coolant flows and is cooled by the air flow generated by the fan. The thermal management module is now designed such that, in the event of a fault in the high-voltage battery, for example when a battery cell of the high-voltage battery passes thermally, it connects the fan to the 12V battery in order to drive the same. In this case, therefore, not only the coolant pump but also the fan of the cooling device continues to be operated, as a result of which particularly efficient cooling of the high-voltage battery can be achieved. In the same way, it is of course also possible for a compressor or further components, for example of an air conditioning system, to be connected to the 12V battery by the thermal management module for the purpose of supplying voltage in the event of a fault in the high-voltage battery.According to the invention, the thermal management module is designed in such a way that, in the event of a fault in the high-voltage battery, it interrupts an electrical connection between the high-voltage battery and the cooling device. According to the invention, the thermal management module is designed in such a way that, in the event of a fault in the high-voltage battery, it completely interrupts the electrical connection of the high-voltage battery to all other components and thus electrically isolates the high-voltage battery. As a result, the remaining components can be reliably protected, for example, from short circuits which can occur during a thermal runaway of a battery cell.In a particularly preferred embodiment of the electric vehicle according to the invention, a temperature sensor is arranged on the high-voltage battery, which is connected to the thermal management module in a communicating manner and is designed to detect a fault event, in particular to detect a thermal runaway of a battery cell of the high-voltage battery. Such a temperature sensor thus continuously or at least in turn detects the temperature at individual battery cells of the high-voltage battery or at the high-voltage battery itself and can infer a fault case of the high-voltage battery in the case of a detected temperature lying above a predefined limit value, whereupon it transmits a corresponding signal to the thermal management module and said thermal management module then transfers the voltage supply of at least the coolant pump to the 12V battery. Such temperature sensors are not only cost-effective, but also small with regard to their external dimensions, as a result of which a required installation space requirement is minimal.The present invention is further based on the general idea of specifying a method for operating an electric vehicle described in the preceding paragraphs, in which, in normal operation, the high-voltage battery is cooled by means of the cooling device and the cooling device is supplied with electrical voltage from the high-voltage battery via the DC / DC converter. The DC / DC converter reduces the voltage of the high-voltage battery, for example from 400 V, to 12 V, which is required for driving, for example, the coolant pump, a compressor and / or a fan of a cooler of the cooling device. In the event of a fault in the high-voltage battery, for example in the event of a battery cell of the high-voltage battery undergoing thermal runaway, the thermal management module connects at least the coolant pump for driving the same to the 12V battery, as a result of which the cooling of the high-voltage battery can continue to be maintained even in the event of failure of the same, and in particular thermal runaway of further battery cells of the high-voltage battery can be reliably prevented. With the method according to the invention, a redundant voltage supply of the cooling device or at least of the coolant pump of the cooling device is thus effected by the high-voltage battery and the 12V battery, wherein the high-voltage battery assumes the voltage supply of at least the coolant pump of the cooling device in normal operation, while the 12V battery assumes the voltage supply of at least the coolant pump of the cooling device in the event of a fault of the high-voltage battery. Damage to the electric vehicle according to the invention in particular in the event of a thermal runaway of a battery cell of the high-voltage battery can thereby be significantly reduced.In the method according to the invention, the cooling device has a fan in the region of the cooler, wherein the thermal management module connects the fan to the 12V battery in the event of a fault in the high-voltage battery in order to drive the latter. In this case, therefore, not only is the coolant pump further supplied with voltage and can thereby be operated further, but also the fan in the same way, as a result of which the cooling device can continue to provide its cooling effect for the high-voltage battery.According to the invention, in the event of a fault in the high-voltage battery, the thermal management module interrupts an electrical connection to all other components, as a result of which the high-voltage battery is electrically insulated. Damage to further components, for example caused by short circuits due to the thermal runaway of battery cells of the high-voltage battery, can thereby be avoided.In a further advantageous embodiment of the method according to the invention, at least one temperature sensor is arranged on the high-voltage battery, which temperature sensor is connected to the thermal management module in a communicating manner and which transmits a signal to the thermal management module when a fault situation of the high-voltage battery is detected, in particular when a battery cell of the high-voltage battery is detected by thermal runaway, whereupon said thermal management module transfers the voltage supply of the cooling device from the high-voltage battery to the 12V battery and thereby maintains the cooling of the high-voltage battery further even in the event of a fault situation of the high-voltage battery. By means of such a temperature sensor, continuous monitoring of the temperature of individual battery cells or generally of the high-voltage battery can be achieved, so that announcing a thermal runaway of a battery cell of the high-voltage battery can already be used to transmit the voltage supply of the cooling device from the high-voltage battery to the 12V battery. In particular, even when announcing a thermal runaway of a battery cell occurs, the cooling effect can be enhanced or a corresponding signal can be transmitted to a driver (m / w / d) of the electric vehicle, as a result of which the driver can take corresponding safety measures.Further important features and advantages of the invention are evident from the dependent claims, from the drawings and from the associated description of the figures with reference to the drawings.It is understood that the features mentioned above and those still 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. The above-mentioned components of a superordinate unit, such as a device, a device or an arrangement, which are designated separately, and which will be mentioned below, can form separate components or components of this unit or can be integral regions or sections of this unit, even if this is illustrated differently in the drawing.Preferred exemplary embodiments of the invention are illustrated in the drawings and are explained in more detail in the following description, wherein the same reference numerals refer to the same or similar or functionally the same components.They show, in each case schematically FIG. 1 shows an electric vehicle according to the invention, FIG. 2 shows individual method steps of a method according to the invention for operating the electric vehicle according to the invention.According to FIG. 1, an electric vehicle 1 according to the invention has a high-voltage battery 2 with individual battery cells 3 for supplying voltage to an electric drive device 4. The high-voltage battery 2 can be designed, for example, as a so-called traction battery and provide the required electrical energy for the electrical propulsion of the electric vehicle 1 according to the invention. Furthermore, the electric vehicle 1 according to the invention has a 12V battery 5 for the electrical supply of customary components, such as, for example, a sound system of the electric vehicle 1. In order to be able to achieve the most efficient possible cooling in this case, the high-voltage battery 2 is usually immersion-cooled, i.e. supplied with a dielectric coolant, which directly washes around the individual battery cells 3 of the high-voltage battery 2. The cooling device 6 comprises a coolant pump 8, a cooler 9 and a fan 10, which conveys an air flow through the cooler 9 in a known manner and cools the coolant flowing in the heat exchanger block of the cooler 9. In normal operation of the electric vehicle 1 according to the invention, the cooling device 6 is supplied with electrical voltage by the high-voltage battery 2, wherein a so-called DC / DC converter 11 is arranged between the high-voltage battery 2 and the cooling device 6, said converter transforming the voltage of the high-voltage battery 2, for example 400V, to an operating voltage of the coolant pump 8.According to the invention, a thermal management module 12 is now provided, which is designed in such a way that, in the event of a fault in the high-voltage battery 2, it connects at least the coolant pump 8 of the cooling device 6 to the 12V battery 5 in order to drive the same and thereby maintains the cooling of the high-voltage battery 2 even in the event of a failure of the same. Such a fault may occur, for example, when a battery cell 3 of the high-voltage battery 2 passes thermally, which may lead to failure of the high-voltage battery 2 or at least to a reduced power output of the high-voltage battery 2. The thermal runaway of a battery cell 3 of the high-voltage battery 2 always carries the risk of thermal runaway of further battery cells 3, which must necessarily be avoided in order to limit damage to the electric vehicle 1 and to ensure safety for vehicle occupants. This is realized by the thermal management module 12 according to the invention, which, in the event of a fault in the high-voltage battery 2, i.e. for example in the event of a thermal runaway of a battery cell 3 of the high-voltage battery 2, which would lead, for example, to a failure of the high-voltage battery 2 and thus to a failure of the cooling device 6, continues to operate the cooling device 6 via the 12V battery 5 and thus at least reduces, preferably even eliminates, the risk of the thermal runaway of further battery cells 3.The cooling device 6 has the aforementioned fan 10 in the region of the cooler 9, wherein the thermal management module 12 can be designed in such a way that, in the event of a fault in the high-voltage battery 2, it likewise connects the fan 10 to the 12V battery 5 in order to drive the same, with the result that, in the event of a fault in the high-voltage battery 2, not only the coolant pump 8, but also the fan 10 are operated further.A temperature sensor 13 can be arranged on the high-voltage battery 2, which is connected to the thermal management module 12 in a communicating manner and is designed to detect a fault event, in particular to detect a thermal runaway of a battery cell 3 of the high-voltage battery 2. If the temperature sensor 13 thus detects an unusually high temperature rise, which indicates that a battery cell 3 has passed through thermally, it transmits a corresponding signal to the thermal management module 12, which thereupon transmits the voltage supply of the cooling device 6 from the high-voltage battery 2 to the 12V battery 5 and thereby maintains the cooling of the high-voltage battery 2 even in the event of a failure of the same.FIG. 2 shows a method according to the invention for operating the electric vehicle 1 shown in FIG. 1, in which, in a method step A during normal operation, the high-voltage battery 2 is cooled by means of the cooling device 6 and the cooling device 6, that is to say the coolant pump 8 and the fan 10, is supplied with electrical voltage from the high-voltage battery 2 via the DC / DC converter 11. In method step B, the thermal management module 12 now detects a fault situation in the high-voltage battery 2, for example a thermal runaway of a battery cell 3 of the high-voltage battery 2, in particular by means of a temperature sensor 13, whereupon the thermal management module 12 connects at least the coolant pump 8 to the 12V battery 5 of the electric vehicle 1 in method step C in order to drive the same. Purely theoretically, the thermal management module 12 can of course also electrically connect further components 14 to the 12V battery 5, so that these are also supplied with electrical voltage by the 12V battery 5. This is of particular advantage in particular in the event of a total failure of the high-voltage battery 2, which also supplies the remaining components 14 with electrical voltage via the DC / DC converter 11 in normal operation.In the event of a fault in the high-voltage battery 2, the thermal management module 12 naturally connects not only the coolant pump 8, but also the fan 10 on the cooler 9 for driving the same to the 12V battery 5 electrically and thus drives the fan 10. It is furthermore conceivable that in the event of a fault in the high-voltage battery 2, which is detected by the thermal management module 12, the latter opens a switch 15 and thereby interrupts an electrical connection of the high-voltage battery 2 to the cooling device 6 or generally to the DC / DC converter 11 and electrically isolates the high-voltage battery 2.All in all, with the electric vehicle 1 according to the invention and the method according to the invention for operating the electric vehicle 1, the consequences of a fault at the high-voltage battery 2, for example caused by a thermal runaway of a battery cell 3 of the high-voltage battery 2, can be significantly reduced, as a result of which not only repair costs can be reduced, but also a risk for vehicle occupants.

Claims

Electric vehicle (1), - having a high-voltage battery (2) for supplying voltage to an electric drive device (4), - having a 12V battery (5), characterized by - a cooling device (6) for cooling the high-voltage battery (2), having a cooling circuit (7) in which the high-voltage battery (2) is incorporated, a cooler (9), a fan (10) arranged in the region of the cooler (9) and a coolant pump (8), - a DC / DC converter (11), via which the coolant pump (8) and the fan (10) are connected to the high-voltage battery (2) for drive in a normal mode, - a thermal management module (12) which is designed in this way, in the event of a fault in the high-voltage battery (2), it connects the coolant pump (8) and the fan (10) to the 12V battery (5) in order to drive the same, and completely interrupts the electrical connection of the high-voltage battery (2) to all other components (14), and thus electrically isolates the high-voltage battery (2).Electric vehicle (1) according to Claim 1, characterized in that a temperature sensor (13) is arranged on the high-voltage battery (2), which temperature sensor is connected in a communicating manner to the thermal management module (12) and is designed to detect a fault event, in particular to detect a thermal runaway of a battery cell (3) of the high-voltage battery (2).Method for operating an electric vehicle (1) according to Claim 1, in which - in normal operation the high-voltage battery (2) is cooled by means of the cooling device (6) and the high-voltage battery (2) supplies the coolant pump (8) and the fan (10) with electrical voltage via the DC / DC converter (11), - in the event of a fault in the high-voltage battery (2), the thermal management module (12) connects the coolant pump (8) and the fan (10) of the cooling device (6) to the 12V battery (5) in order to drive the latter, and completely interrupts the electrical connection of the high-voltage battery (2) to all other components (14) and thus electrically isolates the high-voltage battery (2).Method according to Claim 3, characterized in that a temperature sensor (13) is arranged on the high-voltage battery (2), which temperature sensor is connected in a communicating manner to the thermal management module (12) and which transmits a signal to the thermal management module (12) when a fault event is detected, in particular when a battery cell (3) of the high-voltage battery (2) is detected to pass thermally.

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