Cooling system for battery-powered vehicles

Abstract

The invention relates to a cooling system (10), in particular a high-voltage battery cooling system for a utility vehicle, comprising a battery unit (5'), an on-board charger (14) for charging the battery unit (5') with externally supplied electrical energy, and an electrical drive unit (5) driven by the electrical energy of the battery unit (5'), wherein the cooling system has a primary cooling circuit (2) of a coolant for cooling the electric drive unit (5) and the on-board charger (14), and a secondary cooling circuit (4) of the coolant for cooling the battery unit (5'), wherein the primary cooling circuit (2) comprises a first circuit pump arrangement (7), a heat exchanger (17) and a fan (18), wherein the secondary cooling circuit (4) comprises a second circuit pump arrangement (7'), at least one heat exchanger (16) and a refrigeration system (19). According to the invention, the cooling system comprises a plurality of switchable multi-way valves (21, 22, 23, 24) for regulating the coolant flow in the cooling circuits (2, 4), wherein the cooling circuits (2, 4) can be connected to each other or disconnected from each other via the multi-way valves (21, 22, 23, 24) in such a way that they can be selectively operated independently of each other and in an isolated or combined manner, in order to cool the electric drive unit (5) and the battery unit (5').

Description

[0001] Cooling system for battery-electric vehicles

[0002] The invention relates to a cooling system according to the preamble of claim 1, a method according to claim 22 and a commercial vehicle according to the preamble of claim 23.

[0003] Such cooling systems or temperature control systems or thermal management systems are particularly well known and of great importance in the field of battery-electric powered vehicles such as passenger cars or commercial vehicles.

[0004] The aforementioned cooling systems primarily serve to cool drivetrain components of the electrified powertrain, such as electric motors, inverters, battery packs, and on-board chargers. A corresponding coolant is transported through coolant channels and cooling circuits by means of heat or coolant pumps, flowing through the drivetrain components to cool them. The absorbed thermal energy is then directed toward a heat exchanger / radiator on the coolant discharge side to be dissipated to the outside environment. However, the known concepts and systems primarily serve vehicle types that differ in size, design, and functionality from trailers and semi-trailers of vehicle class O.Electrified semi-trailers and commercial vehicles in general typically use high-voltage batteries with high energy capacities (e.g., up to 300 kWh) as energy storage devices to power the electric drive motors. The batteries can have nominal operating voltages of 600–1000 volts.

[0005] Due to space constraints, the battery unit or HV battery packs usually have to be mounted directly on the underside of a semi-trailer frame, which is why existing cooling systems often cannot meet the spatial, mechanical, thermal, or dynamic requirements. Controlling electrified semi-trailers with existing systems is inefficient and can be designed more efficiently.

[0006] Cooling systems are usually controlled via electronically controlled valves, such as multi-way valves. The inherently large dimensions and complexity of HV battery packs in electrified trailers and semi-trailers require a consistently reliable solution that ensures cooling management of both the electric drive unit and the battery unit in every situation. Although battery systems generally do not exhibit significant self-heating, other key drivetrain components such as inverters, electric motors, converters (e.g., DC-DC converters), and on-board chargers can generate considerable heat. This heat is introduced into the cooling system and typically dissipated to the environment through a heat exchanger.

[0007] A disadvantage is that excessive pressure loss often occurs due to excessive pressure resistance within the coolant channels of the cooling circuits or the cooling circuit itself, which can negatively impact the overall energy efficiency of the cooling system. The logistics industry, by far the largest area of ​​application for commercial vehicles and semi-trailer trucks, is also exposed to dynamically changing and extreme weather conditions, which is why cooling is often inefficient and associated with significant losses. At high ambient temperatures, the temperature difference between the cooling system and the environment can become critical, especially for the battery unit. The cooling systems are often inadequately adjusted to the actual temperature ranges of the individual components of the battery unit and electric drive unit.

[0008] Furthermore, the ability to integrate the valves and connect them, for example, to existing heat pump systems is of utmost importance to ensure maximum usability in various vehicle configurations. Overall, there is therefore a great need for optimization regarding the efficiency and functionality of such cooling systems, especially if they are to be used in battery-electric commercial vehicles or trailers with high-voltage batteries.

[0009] The aim of the invention is to overcome these and other disadvantages of the prior art and to provide an improved, reliable cooling system for a commercial vehicle that ensures energy-efficient cooling of an electric drive and battery unit.

[0010] Main features of the invention are defined in the characterizing part of claim 1. Embodiments are the subject of claims 2 to 23.

[0011] In a cooling system, in particular a high-voltage battery cooling system for a commercial vehicle, which comprises a battery unit, an on-board charger for charging the battery unit with externally supplied electrical energy, and an electric drive unit driven by the electrical energy of the battery unit, wherein the cooling system has a primary cooling circuit of a coolant for cooling the electric drive unit and the on-board charger and a secondary cooling circuit of the coolant for cooling the battery unit, wherein the primary cooling circuit comprises a first circulation pump arrangement, a heat exchanger, and a fan, wherein the secondary cooling circuit comprises a second circulation pump arrangement, at least one heat exchanger, and a refrigeration system, the invention provides that the cooling system comprises a plurality of switchable multi-way valves for regulating the coolant flow in the cooling circuits,The cooling circuits can be connected or separated via the multi-way valves in such a way that they can be operated either independently and in isolation or combined to cool the electric drive unit and the battery unit. The operation of electric commercial vehicles or electric semi-trailers is associated with special requirements regarding efficient temperature control, which arise from the specific thermal challenges.

[0012] Due to the cooling system according to the invention and the arrangement according to the invention and the optional switching option of the multi-way valves for controlling the cooling system and the two cooling circuits, a number of advantageous technical effects occur which have an overall positive impact on the functionality, efficiency, costs, quality and service life of the cooling system and the electrified trailer.

[0013] This advantageously allows the coolant to circulate, as needed, either in isolation through the primary and secondary cooling circuits to cool the electric drive unit and battery unit, or combined to form a common cooling circuit for cooling the electric drive unit and battery unit. This results in an intelligent and demand-based control strategy that can respond dynamically to different operating conditions and environmental situations, maximizing the efficiency of the entire cooling system while minimizing energy consumption.

[0014] The primary cooling circuit alone could only efficiently dissipate heat energy from the battery unit up to a certain ambient temperature. Since the battery unit has a lower operating temperature than the drive components of the electric drive unit, the invention advantageously provides an additional, active secondary cooling circuit to ensure cooling at higher temperatures.

[0015] Preferably, the coolant can be supplied by the first and second circulation pump arrangements in a first flow direction to the components of the electric drive unit and the battery unit that are to be cooled. Further preferably, the coolant can be returned in a second flow direction, after flowing through the components for cooling, toward the heat exchanger or refrigeration system. This ensures that the thermal energy absorbed during the cooling process is always dissipated to the outside environment.

[0016] According to a preferred embodiment, the electric drive unit can have at least one inverter and / or at least one converter. Further preferably, the electric drive unit can have a dual drive, wherein the dual drive can comprise two electric motors and two associated inverters, wherein the electric drive unit can have at least one DC-DC converter.

[0017] Preferably, the heat exchanger of the primary cooling circuit can be designed as a radiator, wherein the heat exchanger and the fan can be designed as a common radiator-fan unit. This creates a compact component unit that is simple and cost-effective to manufacture, via which the primary cooling circuit can be operated and heat dissipation to the environment is ensured. Further preferably, the first circulation pump arrangement can be designed as a coolant pump, wherein the coolant pump can use the radiator-fan unit during operation as additional assistance for transporting the coolant. This represents a particularly efficient method, particularly from a fluid mechanics and energy perspective. This further increases the overall energy efficiency of the cooling system.

[0018] According to a further preferred embodiment, all individual components of the electric drive unit and the on-board charger can be arranged and connected in parallel with the heat exchanger and fan of the primary cooling circuit. This allows the coolant to selectively flow through the parallel coolant channels and the components connected to them during the cooling process of the primary cooling circuit and then flow back toward the radiator-fan unit or heat exchanger and fan to dissipate the absorbed heat energy to the environment.

[0019] The battery unit can preferably have at least one HV battery string, wherein the at least one HV battery string comprises at least three drive battery packs. Further preferably, the battery unit can have three HV battery strings, wherein the three HV battery strings each comprise three drive battery packs through which the coolant of the cooling system flows and is cooled. The battery unit to be cooled or the drive battery packs of the battery strings are electrically interconnected and can preferably have a total nominal voltage of 600 V to 800 V, more preferably of approximately 650 V to 660 V, in particular of 655 V. The battery unit to be cooled or the drive battery packs of the battery strings can have a total nominal energy capacity of approximately 300 kWh. The battery strings or the battery string can also have a lower or higher total nominal energy capacity.Preferably, a heat exchanger can be arranged in the secondary cooling circuit for each of the three HV battery strings, wherein two distributor elements can be provided in the secondary cooling circuit, which are connected on the one hand via a coolant channel to the third and fourth multi-way valve and on the other hand via three split coolant channels to the three heat exchangers.

[0020] Preferably, the battery strings can each have additional distribution elements on their coolant supply and discharge sides, wherein the distribution elements of the battery strings can, on the one hand, be connected to the second circulation pump arrangement and to the heat exchangers via a coolant channel each, and, on the other hand, can each have three split coolant channels for connecting to the battery strings. The distribution elements advantageously allow the coolant flow to be divided into three channels to the heat exchangers in a cost-effective, simple, and reliable manner.

[0021] According to a further preferred embodiment, the heat exchangers of the primary and / or secondary cooling circuit can be designed as plate-shaped heat exchangers. This has proven to be a particularly efficient and cost-effective cooling method. At the same time, the plate shape utilizes a relatively large longitudinal surface of the semi-trailer frame. Since installation space is already limited, this measure proves particularly advantageous. The plate shape also supports uniform, efficient heat transfer and is simple and cost-effective to manufacture.

[0022] Preferably, the second circulation pump arrangement of the secondary cooling circuit can be a heat pump arrangement, wherein the heat pump arrangement is already installed in the commercial vehicle or semi-trailer. The second circulation pump arrangement or heat pump arrangement circulates the coolant in the coolant channels of the secondary cooling circuit and ensures sufficient flow pressure. Since the cooling system can be adapted to an already provided heat pump arrangement, energy consumption is further reduced and overall energy efficiency is increased. The secondary cooling circuit can thus be operated efficiently with respect to the battery unit and optionally connected to the refrigeration system. According to a further preferred embodiment, the coolant can be a water-glycol mixture.The water-glycol mixture can be formulated in such a way that it can be used to cool the individual components in both the primary and secondary cooling circuits. This advantageously provides a single coolant that can be effectively used for cooling in both cooling circuits and enables a reliable connection between the cooling circuits.

[0023] Preferably, an automatic and adaptive control system can be implemented using the cooling system and the multi-way valves, which provides automatic adjustment of the cooling system through the use of special algorithms and status parameters. This advantageously provides automated adjustment to different cooling requirements. Furthermore, adaptive control algorithms can be implemented that are not based solely on fixed limit values, but also react dynamically to changes in the operating state of the semi-trailer and the environment. This can further improve the efficiency of the cooling system.

[0024] According to a preferred embodiment, at least four multi-way valves can be provided, wherein the primary cooling circuit comprises a first and a second multi-way valve, and wherein the secondary cooling circuit comprises a third and a fourth multi-way valve. The fact that two switchable multi-way valves are provided in each cooling circuit opens up several channel connection and switching options to map the desired circuits. Through intelligent control of these four multi-way valves, i.e. through targeted opening or closing of coolant channels within the cooling circuits, the more energy-intensive secondary active cooling circuit is only used when needed, in particular for cooling the battery unit. In other operating states, the passive primary cooling circuit is sufficient.This demand-based activation and switching of the cooling circuits significantly reduces electrical energy consumption and increases the range of the electrified semi-trailer. In addition to reducing operating costs, less wear and tear and longer maintenance intervals also lead to lower maintenance costs. This also has a positive overall impact on the total operating costs of the electrified trailer.

[0025] According to a further preferred embodiment, the second multi-way valve can selectively connect the on-board charger to the primary cooling circuit in parallel with the electric drive unit, wherein the first multi-way valve can selectively connect the primary cooling circuit to the secondary cooling circuit. The parallel circuit and arrangement of the on-board charger is particularly well suited for the targeted integration of the charger into the primary cooling circuit or for the targeted isolation from the primary cooling circuit, for example via a bypass circuit. By selectively connecting the two cooling circuits as needed via the first multi-way valve, the cooling of the battery unit can advantageously be decoupled from the other components of the electric drive unit, thereby enabling demand-based temperature control.The resulting reduced operation of the secondary cooling circuit leads to less wear and tear, thus extending the maintenance intervals of the system, the multi-way valves, and other system components. This, in turn, increases the service life of the entire system.

[0026] The multi-way valves can preferably be designed as 3 / 2-way valves, whereby the multi-way valves can be controlled and switched via a common control unit. The 3 / 2-way valves are particularly well suited for the desired circuits and operating modes because the valves comprise three paths and two switching positions. This allows all intended circuits or sub-circuits and combinations to be implemented during cooling. The design as a common control unit also simplifies the control on the software side and provides a simple implementation interface for algorithms and functions. The four highly integrated 3 / 2-way valves form a set of multi-way valves that further supports flexible and intelligent control of the cooling circuits.The integration allows the cooling circuits to be combined or isolated as needed, enabling more efficient cooling and reducing the energy requirements of the overall system.

[0027] According to an alternative embodiment of the invention, separate control units can be provided, whereby the two control units of the primary and secondary cooling circuits are signal-connected and can act and operate together in a coordinated manner within the cooling system. This can increase the flexibility and efficiency with which the temperature control for the electric drive unit and the battery unit is managed.

[0028] According to a further preferred embodiment, the multi-way valves can be designed separately and arranged at different positions in the cooling system, wherein the multi-way valves are designed in such a way that they can be integrated modularly into various positions of the cooling system. This flexibility advantageously enables a broader applicability of the multi-way valve set in various vehicle configurations and also facilitates adaptation to specific design requirements. The resulting modular integration results in easier installation and maintenance of the system, which simultaneously leads to improved adaptability of the cooling system.

[0029] According to an alternative embodiment, the set of multi-way valves, or the four multi-way valves, can be designed as a single piece and from the same material, with the individual paths of the four multi-way valves being formed on a common base body. This advantageously saves installation space. Preferably, the paths can be arranged on the base body in such a way that a fluid-tight connection of the lines or coolant channels to the valves can be easily achieved using clamps. Further preferably, the common base body, which comprises all four multi-way valves, can be designed as a hollow cylinder. This offers a particularly compact solution that is cost-effective and easy to manufacture and at the same time saves installation space. One disadvantage of the valve device set can be the additional space required for installation.Compared to a conventional cooling system, which does not require a four-way valve assembly, the valve positions in the valve assembly require more space. This can cause problems, particularly in vehicle designs where available space is already limited. The measures mentioned above significantly counteract this.

[0030] According to a further preferred embodiment, the primary cooling circuit can have at least two parallel coolant channels, wherein the primary cooling circuit can be connected to the secondary cooling circuit via the at least two coolant channels, and wherein the two coolant channels can be arranged downstream of the first circulation pump arrangement of the primary cooling circuit. The coolant channels represent a simple connection option and are advantageously used for the connection and combined operation of both cooling circuits. The coolant can thus be optimally distributed depending on the operating state and temperature requirements of the various components. This leads to a significant increase in the efficiency of the entire cooling system by always concentrating the cooling capacity within the cooling system where it is most urgently needed, while simultaneously minimizing the overall energy consumption for cooling.

[0031] According to a further preferred embodiment, a first of the two

[0032] Coolant channels can be connected to the primary cooling circuit via the first multi-way valve, with a second of the two coolant channels being connected to the primary cooling circuit via a T-element. This allows the multi-way valves to act specifically at the connection positions of the coolant channels of the cooling system, opening or closing the channels, depending on the needs and desired operating mode of the cooling system.

[0033] According to a further preferred embodiment, the two coolant channels can be connected via the third and fourth multi-way valves, on the one hand, to the refrigeration system and, on the other hand, to the at least one heat exchanger of the secondary cooling circuit. This allows the refrigeration system to be connected or isolated within the secondary cooling circuit as desired. Overall, this leads to a further improvement in the energy efficiency of the cooling system and the multi-way valves.

[0034] Preferably, the primary cooling circuit can have a flow sensor on each coolant channel of a component of the electric drive unit. Further preferably, both cooling circuits can have one or more pressure sensors for measuring the pressure in the respective coolant channels. This advantageously allows for constant monitoring during cooling to determine whether sufficient coolant is flowing in the coolant channels, and pressure values ​​can be derived for controlling the cooling circuits.

[0035] The first circulation pump arrangement of the primary cooling circuit can preferably be configured with a compressor on each of the coolant supply and discharge sides. The first circulation pump arrangement can preferably be equipped with a pressure sensor on each of the coolant supply and discharge sides, respectively. A first pressure sensor can be arranged on the coolant supply side on an outlet side of the first compressor, and a second pressure sensor can be arranged on the coolant discharge side on an inlet side of the second compressor of the first circulation pump arrangement. This constantly determines a pressure ratio and a possible pressure difference between the inlet and outlet in order to counteract any pressure losses promptly and locally.

[0036] Preferably, advanced, modern sensors can be provided for precise measurement of pressures, temperatures, and flow rates. This can further improve control accuracy. Furthermore, the use of data analytics methods and machine learning to predict and adjust cooling requirements in real time can be planned to further increase system responsiveness and efficiency.

[0037] The primary cooling circuit can preferably comprise at least one equalization tank or expansion tank, wherein the equalization tank can be arranged parallel to the heat exchanger and between the first circulation pump arrangement and the heat exchanger on the primary cooling circuit. Further preferably, the secondary cooling circuit can have a further equalization tank for each of the three battery strings, wherein the equalization tanks of the secondary cooling circuit can be arranged between the battery unit, i.e., the three battery strings and the six distributor elements arranged on the inlet and outlet sides, and the second circulation pump arrangement. The equalization tanks (also called expansion tanks) of the cooling system ensure a constant pressure in the entire system. The equalization tank absorbs excess coolant and minimizes the overpressure in the cooling system.An expansion tank advantageously helps minimize pressure rise during expansion of the heated coolant. It helps maintain the electric drive unit and battery unit at precisely the right temperature.

[0038] Further preferably, each of the three battery strings within the secondary cooling circuit can form its own inner sub-circuit with its associated heat exchanger, so that the expansion tanks can be arranged simultaneously between a coolant supply channel and a coolant discharge channel of a sub-circuit of a battery string.

[0039] The following additional measures and embodiments are primarily aimed at not only improving the direct function of the multi-way valves, but also at increasing the overall efficiency and reliability of the cooling system in electrified semi-trailers.

[0040] According to a preferred embodiment, the multi-way valves can have energy-efficient, modern drives, and the multi-way valves can include an additional recovery device. This advantageously reduces the energy consumption of the valve control itself. Overall, this can further improve the overall energy efficiency of the electrified semi-trailer and the cooling system. According to a further preferred embodiment, the multi-way valves can be designed as proportionally controllable valves. This advantageously allows for finer adjustment of the flow rates, which can offer advantages in certain operating conditions.

[0041] Further preferably, the control of the cooling of the electric drive unit and the battery unit as well as the switching of the multi-way valves of the primary and secondary cooling circuits can be carried out as a function of an ambient temperature and an operating state of the battery unit, wherein the battery unit can be operated in a discharging mode when the electric drive unit has a driving effect, and wherein the battery unit can be operated in a charging mode when the on-board charger is connected or when the electric drive unit has a braking effect.

[0042] The primary cooling circuit can preferably be passive. This cooling circuit can preferably be formed from a conventional cooling water system, in which the energy absorbed by the cooling water can be dissipated to the environment via the radiator-fan unit. The primary cooling circuit is responsible for cooling the electric drive unit and the on-board charger. These components operate in a comparatively high temperature range, which is why passive cooling, which depends on the ambient temperature, is sufficiently effective. This avoids oversizing and further reduces energy consumption.

[0043] In contrast, the secondary cooling circuit can be of an active nature. Here, the energy stored in the cooling water is released into the environment through a heat exchanger integrated into the refrigeration system. This preferably occurs through a phase transition of the coolant from gaseous to liquid. This circuit is specifically designed for cooling the battery unit, as it has a lower thermal operating range than the other components and must be effectively cooled even at high ambient temperatures.

[0044] Through intelligent control of the multi-way valves based on the ambient temperature and the operating state of the battery unit, the more energy-intensive secondary active cooling circuit is activated only when needed, specifically for cooling the battery unit's battery strings. In other operating states, the passive primary cooling circuit is sufficient, further reducing electrical energy consumption and thus further increasing the range of the electrified semi-trailer. Overall, this provides intelligent control capability that allows cooling requirements to be dynamically adapted to the respective ambient conditions. This means that the system is able to automatically regulate the cooling output based on the current ambient temperature and the vehicle's operating conditions.This positively contributes significantly to energy efficiency and to maintaining optimal operating temperatures for the components of the battery unit and electric drive unit.

[0045] Preferably, the battery unit or the individual battery strings and drive battery packs of the battery unit can have a use and operating temperature of 0°C to 60°C during charging. Further preferably, the battery unit or the individual battery strings and drive battery packs of the battery unit can have a use and operating temperature of -30°C to 60°C during discharging.

[0046] According to a further preferred embodiment of the invention, it can be provided that in a first operating mode, in which the ambient temperature is at least 15°C and the battery unit is operated in discharge mode, the multi-way valves are switched such that the primary and secondary cooling circuits are operated independently and in isolation from one another, with the primary cooling circuit flowing through all individual components of the electric drive unit and the heat exchanger during cooling, and the secondary cooling circuit flowing through the refrigeration system, the distribution elements, the heat exchangers, and the battery unit during cooling. This intelligent switching and use of the multi-way valves ensures optimal cooling of the various components while simultaneously maximizing the energy efficiency of the overall system.This differentiated and independent control of the cooling circuits contributes significantly to increasing the performance and reducing the energy consumption of the electrified semi-trailer. This mode particularly affects driving with the semi-trailer and the cooling system in high ambient temperatures, when the battery unit is discharged and the electric motors drive the semi-trailer.

[0047] According to a further preferred embodiment of the invention, it can be provided that in a second operating mode, in which the ambient temperature is less than 15°C and the battery unit is operated in discharge mode, the multi-way valves are switched such that the primary and secondary cooling circuits are operated in conjunction with one another, with the combined cooling circuit flowing through all individual components of the electric drive unit and the heat exchanger of the primary cooling circuit, as well as the distribution elements, the heat exchangers, and the battery unit of the secondary cooling circuit during cooling. This targeted switching of the multi-way valves advantageously achieves optimal use of the cooling resources in the second operating mode.This enables efficient cooling of the battery packs of the battery unit and the drive components of the electric drive unit, even at lower ambient temperatures, while significantly contributing to the energy efficiency of the entire cooling system. This mode particularly affects semi-trailer driving and the cooling system in low ambient temperatures, when the battery unit is discharged and the electric motors are driving the semi-trailer.

[0048] According to a further preferred embodiment, in a third operating mode, in which the ambient temperature is at least 20°C and the battery unit is operating in charging mode, the multi-way valves can be connected such that the primary and secondary cooling circuits operate independently and in isolation from one another, with the primary cooling circuit flowing through the on-board charger and the heat exchanger during cooling, and the secondary cooling circuit flowing through the refrigeration system, the distribution elements, the heat exchangers, and the battery unit during cooling. This isolated operating strategy maximizes the efficiency of the cooling system by optimally adapting the coolant requirements and energy consumption depending on the operating state of the trailer.This mode particularly applies to charging situations of the electrified semi-trailer (rest position) when a corresponding charging plug is connected to the on-board charger and charges the battery unit with external energy.

[0049] According to a further preferred embodiment, in a fourth operating mode, in which the ambient temperature is less than 20°C and the battery unit is operated in charging mode, the multi-way valves can be connected such that the primary and secondary cooling circuits are operated in conjunction with one another, with the combined cooling circuit flowing through the on-board charger and the heat exchanger of the primary cooling circuit, as well as the distribution elements, the heat exchangers, and the battery unit of the secondary cooling circuit during cooling. Overall, this operating scenario offers an optimized solution for efficient cooling of the battery unit during charging at low ambient temperatures, thus contributing to the overall efficiency and cost-effectiveness of the electrified semi-trailer and the cooling system.

[0050] According to a further preferred embodiment, the refrigeration system can comprise a PTC heating element for preconditioning the battery unit, wherein the battery unit can be tempered to an operating temperature above 0°C by the PTC heating element in the secondary cooling circuit if the ambient temperature of the cooling system is below 0°C before the start of charging of the battery unit. At high ambient temperatures, the temperature delta between the cooling system and the environment can become critical, especially for the battery unit. An excessively high delta can impair the thermal integrity of the battery cells, which can lead to a reduced service life, reduced performance, or even damage to the battery unit. Preconditioning using the PTC heating element of the refrigeration system significantly counteracts this.

[0051] In preconditioning mode, the cooling system can preferably be switched and controlled analogously to the third operating mode. When preconditioning the battery pack's battery strings to achieve an optimal thermal operating window, the four multi-way valves ensure that the coolant heated by the PTC element exclusively heats the traction batteries without affecting other, less temperature-sensitive drive components. This further improves the overall energy efficiency of the cooling system, as well as the efficiency and longevity of the electrified semi-trailer. On the other hand, in colder climates, where temperatures below 10°C, especially below 0°C, can be very damaging to battery systems, there may be a need for efficient heating or pre-temperature control of the system.Such low temperatures can significantly affect the performance and lifespan of the batteries, which is why the integrated PTC heating element is a particularly advantageous solution.

[0052] According to a further preferred embodiment, the second multi-way valve of the primary cooling circuit can be switched during the battery unit's discharge operation in such a way that it forms a bypass circuit for the on-board charger and prevents coolant from flowing into the coolant channel of the on-board charger. This advantageously achieves an effective reduction in pressure resistance within the cooling circuits and multi-way valves. This is crucial to ensure that the efficiency achieved by the improved cooling system is not neutralized by increased pressure loss in the coolant channels. Low pressure resistance ensures an efficient coolant flow rate, which in turn can further improve the overall performance of the cooling system.The bypass circuits implemented with the multi-way valves offer the positive option of deliberately bypassing various system components when flow is unnecessary and associated with losses. This ensures that only those components requiring cooling, depending on the current state of the electric drive unit and battery unit, are supplied with coolant. This adjustment minimizes the resulting backpressure in the cooling system, further increasing the overall efficiency of the thermal management system. Since the on-board charger is not needed while driving anyway (because the drive battery packs are not being charged), the backpressure in the line, and particularly in the coolant channel of the on-board charger, can be bypassed. This measure reduces the required pump power and thus the energy consumption of the cooling system.

[0053] According to a further preferred embodiment, the second multi-way valve of the primary cooling circuit and an additional check valve can be switched during battery unit charging such that the electric drive unit is isolated from the primary cooling circuit and is not subjected to coolant flow. This further reduces energy consumption because the components of the electric drive unit are not active during battery unit charging and therefore generate little to no heat energy. Through the targeted insulation of the electric drive unit, the coolant can cool the on-board charger more effectively, and less heat energy needs to be dissipated to the environment via the heat exchanger. This further improves the efficiency of the cooling system.

[0054] According to a further preferred embodiment, the cooling system can have an emergency circuit for emergency operation, wherein the emergency circuit can form a subcircuit of the primary cooling circuit. The emergency circuit can have at least one compressor and two check valves for pumping purposes, which are switched on in emergency operation or switched such that emergency operation continues to safely cool the desired components or the circulating coolant. This allows the battery unit and the components of the electric drive unit to continue to be cooled effectively and safely despite emergency operation. This leads to an optimization of the usability and robustness of the cooling system.

[0055] According to a further preferred embodiment, the commercial vehicle can be formed by a combination comprising a tractor and a trailer coupled thereto with at least one, preferably three trailer axles, wherein the trailer can have the electric drive unit and the battery unit, and wherein the cooling system can be provided on the electrified trailer.

[0056] Further preferably, the commercial vehicle can be a semitrailer truck and can be formed by a combination of a conventional, diesel-engine-driven semitrailer truck and a semitrailer coupled thereto with three trailer axles, wherein the semitrailer can have the electric drive unit and the battery unit, and wherein the cooling system can be provided on the electrified semitrailer.

[0057] Even more preferably, the electric drive unit can be arranged on a middle one of the three trailer axles of the semi-trailer, wherein the battery unit can be mounted on an underside of a semi-trailer frame.

[0058] Overall, the multi-way valves and the cooling system according to the invention offer a more flexible and efficient solution to meet the different cooling needs of an electrified commercial vehicle or semi-trailer and contribute significantly to increasing performance.

[0059] Further features, details, and advantages of the invention will become apparent from the wording of the claims and from the following description of exemplary embodiments with reference to the drawings. They show:

[0060] Fig. 1 is a schematic representation of a first operating mode of the cooling system according to the invention,

[0061] Fig. 2 is a schematic representation of a second operating mode of the cooling system according to the invention,

[0062] Fig. 3 is a schematic representation of a third operating mode of the cooling system according to the invention, Fig. 4 is a schematic representation of a fourth operating mode of the cooling system according to the invention.

[0063] The cooling system, generally designated 10 in Fig. 1 to Fig. 4, is a high-voltage battery cooling system and is implemented on an electrified semitrailer (not shown) of a commercial vehicle. In particular, the electrified semitrailer uses an electric drive to support the internal combustion engine main drive of a tractor to which the semitrailer is coupled.

[0064] The cooling system 10 comprises a battery unit 5', an on-board charger 14 for charging the battery unit 5' with externally supplied electrical energy and an electric drive unit 5 driven or drivable by the electrical energy of the battery unit 5'. For charging the battery unit 5', no

[0065] 14 corresponding charging plug must be inserted.

[0066] The electric drive unit 5 has a dual drive system consisting of two electric motors 12 and two associated inverters 12'. The electric drive unit 5 also has a DC-DC converter 13. The electric motors 12 drive one axle of the semitrailer or brake the electrified semitrailer in generator mode.

[0067] The battery unit 5' comprises three HV battery strings 15, wherein the three HV battery strings

[0068] 15 each comprise three drive battery packs, through which the coolant of the cooling system flows and is cooled.

[0069] The cooling system 10 comprises a primary cooling circuit 2 of a coolant for cooling the electric drive unit 5 and the on-board charger 14. The cooling system 10 also comprises a secondary cooling circuit 4 for cooling the battery unit 5'. The primary cooling circuit 2 has a first circulation pump arrangement 7 and a heat exchanger 17 designed as a radiator-fan unit and fans 18, through which the thermal energy absorbed in the coolant during cooling is dissipated to the outside environment. The primary cooling circuit 2 is designed to be indirect or passive, with the first circulation pump arrangement 7 being a coolant pump arrangement. The secondary cooling circuit 4 comprises a second circulation pump arrangement 7', three heat exchangers 16, and a refrigeration system 19. The three heat exchangers 16 are plate-shaped. A PTC heating element for preheating or preconditioning the battery unit 5' for charging operation is integrated into the refrigeration system 19.The battery unit 5' can be tempered to an operating temperature above 0° C by the PTC heating element in the secondary cooling circuit 4 if the ambient temperature of the cooling system is less than 0° C before the start of a desired charging operation of the battery unit 5'.

[0070] The second circulation pump assembly 7' of the secondary cooling circuit 4 is a heat pump assembly that is already pre-installed on the commercial vehicle. The heat pump assembly circulates the coolant in the coolant channels of the secondary cooling circuit 4.

[0071] In contrast to the primary cooling circuit 2, the secondary cooling circuit 4 is active in nature. The refrigeration system 19 is designed as a compression refrigeration unit, and the energy stored in the coolant is released to the environment via a heat exchanger within the refrigeration system. This occurs in the secondary cooling circuit 4 by means of the refrigeration system 19 through a deliberately induced phase transition of the coolant from gaseous to liquid.

[0072] In the secondary cooling circuit 4, a heat exchanger 16 is arranged for each of the three HV battery strings 15 of the battery unit 5', wherein two distributor elements 11 are provided in the secondary cooling circuit 4, which are connected on the one hand via a coolant channel to the third and fourth multi-way valve 23, 24 and on the other hand via three split coolant channels to the three heat exchangers 16.

[0073] Furthermore, the cooling system 10 comprises four switchable 3 / 2-way valves 21, 22, 23, 24 for regulating the coolant flow in the two cooling circuits 2, 4. The primary cooling circuit 2 comprises a first and a second 3 / 2-way valve 21, 22, wherein the secondary cooling circuit 4 has a third and a fourth 3 / 2-way valve 23, 24.

[0074] The cooling circuits 2, 4 can be connected to or separated from one another via the four 3 / 2-way valves 21, 22, 23, 24 in such a way that, depending on the operating mode, they can be operated independently and in isolation or combined in conjunction to cool the electric drive unit 5 and the battery unit 5'. The cooling circuits 2, 4 and the 3 / 2-way valves 21, 22, 23, 24 are controlled and switched via a common control unit.

[0075] As can be seen, all individual components of the electric drive unit 5 and the on-board charger 14 are arranged and connected in parallel to the heat exchanger 17 and fan 18 or to the radiator-fan unit of the primary cooling circuit 2.

[0076] The second multi-way valve 22 of the primary cooling circuit 2 can optionally connect the on-board charger 14 to the primary cooling circuit 2 in parallel with the electric drive unit 5, wherein the first multi-way valve 21 can optionally connect the primary cooling circuit 2 to the secondary cooling circuit 4.

[0077] For this purpose, the primary cooling circuit 2 has at least two parallel coolant channels 8 which can be connected to the secondary cooling circuit 4, wherein the two coolant channels 8 are arranged after the first circulation pump arrangement 7 of the primary cooling circuit 2.

[0078] A first of the two coolant channels 8 can be connected to the primary cooling circuit 2 via the first multi-way valve 21 and selectively directs the coolant from the primary cooling circuit 2 into the secondary cooling circuit 4.

[0079] A second of the two coolant channels 8 is connected to the primary cooling circuit 2 via a T-element and can optionally ensure a return of the coolant from the secondary cooling circuit 4 to the primary cooling circuit 2.

[0080] The second coolant channel 8 also has a check valve 6, with the primary cooling circuit 2 comprising additional check valves, which can be used optionally to achieve demand-based cooling of the electric drive unit 5 and the battery unit 5'. The coolant channels 8 are connected via the third and fourth multi-way valves 23, 24, on the one hand, to the refrigeration system 19, and on the other hand, to the three heat exchangers 16 of the secondary cooling circuit 4.

[0081] Each of the three provided battery strings 15 has a further distributor element 11 on its coolant supply and discharge side (inlet and outlet side), wherein the distributor elements 11 of the battery strings 15 are connected, on the one hand, to the second circulation pump arrangement 7' and to the heat exchangers 16 via a coolant channel each, and, on the other hand, each have three split coolant channels for connecting to the battery strings 15.

[0082] The primary cooling circuit 2 has a flow sensor 3 on each coolant channel of a component of the electric drive unit 5. The first and second circulation pump assemblies 7, 7' are symbolically represented as compressors. The coolant is supplied by the circulation pump assemblies 7, 7' in a first flow direction S to the components of the electric drive unit 5 and the battery unit 5' to be cooled and is returned from these in a second flow direction S' towards the heat exchanger 17 or refrigeration system 19 in order to dissipate the thermal energy absorbed during the cooling process to the outside environment. For each battery string 15, a compressor of the second circulation pump assembly 7' or heat pump assembly is provided on the coolant supply side, which compressor is aligned and operates in the first flow direction S.

[0083] Both cooling circuits 2, 4 also have a plurality of pressure sensors 3' for measuring the pressure in the respective coolant channels through which the coolant flows. For this purpose, the primary cooling circuit 2 is equipped with a pressure sensor 3' adjacent to the two illustrated compressors of the first circulation pump arrangement 7, with a first pressure sensor 3' being arranged on the coolant supply side at an outlet side of the first compressor, and a second pressure sensor 3' being arranged on the coolant discharge side at an inlet side of the second compressor of the first circulation pump arrangement 7.

[0084] In the secondary cooling circuit 4, all three compressors of the three battery strings 15 shown are each equipped with a pressure sensor 3' on the inlet and outlet side, with further pressure sensors 3' being arranged between the third and fourth 3 / 2-way valves 23, 24 and the refrigeration system 19.

[0085] The primary cooling circuit 2 further comprises an equalizing tank 9 or expansion tank, wherein the equalizing tank 9 is arranged parallel to the heat exchanger 17 and between the first circulation pump arrangement 7 and the heat exchanger 17 on the primary cooling circuit 2. The secondary cooling circuit 4 provides a further equalizing tank 9 for each of the three battery strings 15, wherein the equalizing tanks 9 of the secondary cooling circuit 4 are arranged between the battery unit 5', i.e. the three battery strings 15 and the six distributor elements 11 arranged on the inlet and outlet sides, and the second circulation pump arrangement 7'.

[0086] Each of the three battery strings 15 forms its own inner sub-circuit with its associated heat exchangers 16 within the secondary cooling circuit 4, so that the expansion tanks 9 are simultaneously arranged between a coolant supply channel and a coolant discharge channel of a sub-circuit of a battery string 15.

[0087] The cooling system has an emergency circuit 20 for emergency operation, wherein the emergency circuit 20 forms a subcircuit of the primary cooling circuit. The emergency circuit 20 has at least one compressor and two check valves 6, which are switched on in emergency operation or are switched such that the emergency operation continues to safely cool the desired components or the circulating coolant.

[0088] The coolant used in the cooling system 10, which flows through the primary and secondary cooling circuits 2, 4, is a water-glycol mixture, wherein the coolant mixture is composed in such a way that it can be used in both the primary and secondary cooling circuits 2, 4 for cooling the individual components.

[0089] The cooling of the electric drive unit 5 and the battery unit 5', as well as the switching of the 3 / 2-way valves 21, 22, 23, 24 of the primary and secondary cooling circuits 2, 4, are controlled depending on the ambient temperature and the operating state of the battery unit 5'. The battery unit 5' is operated in a discharging mode when the electric drive unit 5 is driven by a motor and has a driving effect. The battery unit 5' is operated in a charging mode when the on-board charger 14 is connected or when the electric drive unit 5 has a braking effect in generator mode.

[0090] Fig. 1 schematically illustrates a first operating mode of the cooling system 10. In the first operating mode, the ambient temperature is at least 15° C and the battery unit 5' is operated in discharge mode. The semi-trailer equipped with the cooling system 10 is in ferry mode here and is driven by the electric motors 12 of the electric drive unit 5. The drive battery packs of the battery strings 15 are discharged in the process. The 3 / 2-way valves 21, 22, 23, 24 are connected such that the primary and secondary cooling circuits 2, 4 are operated independently and in isolation from one another, with the primary cooling circuit 2 flowing through all individual components of the electric drive unit 5 and the heat exchanger 17 during cooling, and the secondary cooling circuit 4 flowing through the refrigeration system 19, the distribution elements 11, the heat exchangers 16 and the battery unit 5' during cooling.

[0091] The first and second 3 / 2-way valves 21, 22 close the parallel coolant channels to the secondary cooling circuit 4 and to the on-board charger 14, so that the coolant circulates in a closed circuit through or in the primary cooling circuit 2.

[0092] The third and fourth 3 / 2-way valves 23, 24 also close the channel connection to the primary cooling circuit 2 via the coolant channels 8 on the secondary cooling circuit 4 side, so that the coolant circulates only in the secondary cooling circuit 4 and both cooling circuits 2, 4 are insulated.

[0093] Fig. 2 illustrates a second operating mode of the cooling system 10. In the second operating mode, the ambient temperature is less than 15°C, and the battery unit 5' is operated in discharge mode. The semitrailer equipped with the cooling system 10 is driven by the electric motors 12 of the electric drive unit 5, analogously to the first operating mode, and the drive battery packs of the battery strings 15 are discharged.

[0094] The 3 / 2-way valves 21, 22, 23, 24 are connected such that the primary and secondary cooling circuits 2, 4 are operated in conjunction with one another, with the combined and connected cooling circuit 2, 4 flowing through all individual components of the electric drive unit 5 and the heat exchanger 17 of the primary cooling circuit 2, as well as the distribution elements 11, the heat exchangers 16, and the battery unit 5' of the secondary cooling circuit 4 during cooling. In the second operating mode, the refrigerant does not flow through the refrigeration system 19.

[0095] The first 3 / 2-way valve 21 opens the first parallel coolant channel 8 to the secondary cooling circuit 4 and simultaneously closes the coolant channel in the first flow direction S. The coolant flows into and through the secondary cooling circuit 4 and is then fed back into the primary cooling circuit 2 via the second coolant channel 8. The second 3 / 2-way valve 22 is switched analogously to the first operating mode and switches a bypass to bypass the parallel coolant channel for the on-board charger 14.

[0096] The third and fourth 3 / 2-way valves 23, 24 close the channel connection to the refrigeration system 19 on the secondary cooling circuit 4 side and simultaneously open the coolant channels to the distributors 11 and to the primary cooling circuit 2 via the coolant channels 8, so that the coolant circulates in the first and secondary cooling circuits 2, 4 and both cooling circuits 2, 4 are operated in combination with one another.

[0097] Fig. 3 relates to a third operating mode of the cooling system 10. In the third operating mode, the ambient temperature is at least 20° C, and the battery unit 5' is operated in charging mode. The semi-trailer equipped with the cooling system 10 is charged at a suitable charging station via the on-board charger 14.

[0098] The 3 / 2-way valves 21, 22, 23, 24 are connected in such a way that the primary and secondary cooling circuits 2, 4 are operated independently of one another and in isolation, with the primary cooling circuit 2 only flowing through the on-board charger 14 and the heat exchanger 17 during cooling, and with the secondary cooling circuit 4 flowing through the refrigeration system 19, the distribution elements 11, the heat exchangers 16 and the battery unit 5' during cooling.

[0099] The first 3 / 2-way valve 21 closes the parallel coolant channels 8 to the secondary cooling circuit 4, analogous to the first operating mode. The second 3 / 2-way valve 22, in contrast, opens the parallel coolant channel to the on-board charger 14 and simultaneously closes the continuing coolant channel in the first flow direction S, so that the coolant cannot reach the electric drive unit 5. For this purpose, a check valve 6 is simultaneously provided, which permits this partial circuit connection of the on-board charger 14 and isolates the electric drive unit 5 by fulfilling a blocking function on the coolant discharge side similar to the second 3 / 2-way valve 22 on the coolant supply side.

[0100] The third and fourth 3 / 2-way valves 23, 24 also close the channel connection to the primary cooling circuit 2 via the coolant channels 8 on the secondary cooling circuit 4 side, so that, analogous to the first operating mode, the coolant circulates only in the secondary cooling circuit 4 and both cooling circuits 2, 4 are isolated. Fig. 4 shows a fourth operating mode of the cooling system 10. In the fourth operating mode, the ambient temperature is less than 20°C, and the battery unit 5' is operated in charging mode. The semi-trailer equipped with the cooling system 10 is charged at a suitable charging station via the on-board charger 14.

[0101] The 3 / 2-way valves 21, 22, 23, 24 are connected such that the primary and secondary cooling circuits 2, 4 are operated in conjunction with one another. The combined and connected cooling circuit 2, 4 flows through the on-board charger 14 and the heat exchanger 17 during cooling, and the secondary cooling circuit 4 flows through the distribution elements 11, the heat exchangers 16, and the battery unit 5' during cooling. In the fourth operating mode, the refrigerant does not flow through the refrigeration system 19, similar to the second operating mode.

[0102] The first 3 / 2-way valve 21 opens the first parallel coolant channel 8 to the secondary cooling circuit 4 and, analogously to the second operating mode, closes the coolant channel continuing in the first flow direction S. The coolant thereby flows into and through the secondary cooling circuit 4 and is then fed back into the primary cooling circuit 2 via the second coolant channel 8. The second 3 / 2-way valve 22 is switched analogously to the third operating mode, meaning it opens the parallel coolant channel to the on-board charger 14 and simultaneously closes the continuing coolant channel in the first flow direction S, so that the coolant cannot reach the electric drive unit 5 even in the fourth operating mode.

[0103] The third and fourth 3 / 2-way valves 23, 24 close the channel connection to the refrigeration system 19 on the secondary cooling circuit 4 side, analogously to the second operating mode, and simultaneously open the coolant channels to the distributors 11 and to the primary cooling circuit 2 via the coolant channels 8, so that the coolant circulates in the first and secondary cooling circuits 2, 4 and both cooling circuits 2, 4 are operated in combination with one another.

[0104] The invention is not limited to the embodiments described above, but can be modified in a variety of ways. The dynamic and intelligent cooling system and the multi-way valve arrangement according to the invention are generally suitable for modern battery-electric vehicles. In particular, the cooling system can be used in electrified semi-trailers powered by high-performance motors and HV batteries. Other trailer types and tractor configurations can also be temperature-controlled using the cooling system according to the invention. The exact arrangement and dimensions can vary to ensure that the described switching positions, flow circuits, and functionalities are maintained.

[0105] All features and advantages arising from the claims, the description and the drawing, including design details, spatial arrangements and process steps, can be used individually or in a wide variety of

[0106] Combinations are essential to the invention.

[0107] Reference symbol list

[0108] S first flow direction (coolant supply)

[0109] S' second flow direction (coolant return)

[0110] 2 primary cooling circuit (passive)

[0111] 3 flow sensor

[0112] 3' pressure sensor

[0113] 4 secondary cooling circuit (active)

[0114] 5 Electric drive unit

[0115] 5' battery unit

[0116] 6 Check valve

[0117] 7 first circulation pump arrangement (primary cooling circuit)

[0118] 7' second circuit pump arrangement (secondary cooling circuit)

[0119] 8 First and second coolant channel

[0120] 9 Expansion tank

[0121] 10 Cooling system (HV battery cooling system)

[0122] 11 Distribution element (splitter)

[0123] 12 electric motor

[0124] 12' Inverter

[0125] 13 DC-DC converters

[0126] 14 On-board charger (OBC)

[0127] 15 HV battery strings (three traction battery packs each)

[0128] 16 heat exchangers (secondary cooling circuit)

[0129] 17 Heat exchanger (primary cooling circuit)

[0130] 18 fans (radiator-fan unit)

[0131] 19 Refrigeration system (compression refrigeration unit)

[0132] 20 Emergency circuit (partial circuit)

[0133] 21 first multi-way valve (3 / 2-way valve)

[0134] 22 second multi-way valve (3 / 2 way valve)

[0135] 23 third multi-way valve (3 / 2-way valve)

[0136] 24 fourth multi-way valve (3 / 2-way valve)

Claims

Patent claims 1. Cooling system (10), in particular a high-voltage battery cooling system for a commercial vehicle, comprising a battery unit (5'), an on-board charger (14) for charging the battery unit (5') with externally supplied electrical energy, and an electric drive unit (5) driven by the electrical energy of the battery unit (5'), wherein the cooling system has a primary cooling circuit (2) of a coolant for cooling the electric drive unit (5) and the on-board charger (14) and a secondary cooling circuit (4) of the coolant for cooling the battery unit (5'), wherein the primary cooling circuit (2) comprises a first circulation pump arrangement (7), a heat exchanger (17), and a fan (18), wherein the secondary cooling circuit (4) comprises a second circulation pump arrangement (7'), at least one heat exchanger (16), and a refrigeration system (19), characterized in that the cooling system comprises a plurality of switchable multi-way valves (21, 22, 23,24) for regulating the coolant flow in the cooling circuits (2, 4), wherein the cooling circuits (2, 4) can be connected to or separated from one another via the multi-way valves (21, 22, 23, 24) in such a way that they can be operated either independently of one another and in isolation or combined in connection for cooling the electric drive unit (5) and the battery unit (5').

2. Cooling system according to claim 1, characterized in that at least four multi-way valves (21, 22, 23, 24) are provided, wherein the primary cooling circuit (2) comprises a first and a second multi-way valve (21, 22), and wherein the secondary cooling circuit (4) comprises a third and a fourth multi-way valve (23, 24).

3. Cooling system according to claim 2, characterized in that the second multi-way valve (22) selectively connects the on-board charger (14) parallel to the electric drive unit (5) to the primary cooling circuit (2), wherein the first multi-way valve (21) selectively connects the primary cooling circuit (2) to the secondary cooling circuit (4).

4. Cooling system according to one of the preceding claims, characterized in that the multi-way valves (21, 22, 23, 24) are designed as 3 / 2-way valves, wherein the multi-way valves (21, 22, 23, 24) can be controlled and switched via a common control unit.

5. Cooling system according to one of the preceding claims, characterized in that the electric drive unit (5) has a double drive which comprises two electric motors (12) and associated inverters (12'), wherein the electric drive unit (5) has at least one DC-DC converter (13).

6. Cooling system according to one of the preceding claims, characterized in that all individual components of the electric drive unit (5) and the on-board charger (14) are arranged and connected in parallel to the heat exchanger (17) and fan (18) of the primary cooling circuit (2).

7. Cooling system according to one of the preceding claims, characterized in that the primary cooling circuit (2) can be connected to the secondary cooling circuit (4) via at least two parallel coolant channels (8), wherein the two coolant channels (8) are arranged downstream of the first circulation pump arrangement (7) of the primary cooling circuit (2).

8. Cooling system according to claim 7, characterized in that one of the two coolant channels (8) can be connected to the primary cooling circuit (2) via the first multi-way valve (21), wherein the other of the two coolant channels (8) is connected to the primary cooling circuit (2) via a T-element.

9. Cooling system according to claim 7 or 8, characterized in that the coolant channels (8) are connected via the third and fourth multi-way valve (23, 24) on the one hand to the refrigeration system (19) and on the other hand to the at least one heat exchanger (16) of the secondary cooling circuit (4).

10. Cooling system according to one of the preceding claims, characterized in that the battery unit (5') has three HV battery strings (15), wherein the three HV battery strings (15) each comprise three drive battery packs through which the coolant of the cooling system flows and is cooled.

11. Cooling system according to claim 10, characterized in that in the secondary cooling circuit (4) for each of the three HV battery strings (15) a Heat exchanger (16) is arranged, wherein two distributor elements (11) are provided in the secondary cooling circuit (4), which are connected on the one hand via a coolant channel to the third and fourth multi-way valve (23, 24) and on the other hand via three split coolant channels to the three heat exchangers (16).

12. Cooling system according to claim 10 or 11, characterized in that the battery strings (15) each have further distributor elements (11) on their coolant supply and discharge sides, wherein the distributor elements (11) of the battery strings (15) are connected on the one hand via a respective coolant channel to the second circulation pump arrangement (7') and to the heat exchangers (16) and on the other hand each have three split coolant channels for connection to the battery strings (15).

13. Cooling system according to one of the preceding claims, characterized in that the coolant is a water-glycol mixture, the coolant mixture being composed in such a way that it can be used in both the primary and the secondary cooling circuit (2, 4) for cooling the individual components.

14. Cooling system according to one of the preceding claims, characterized in that the control of the cooling of the electric drive unit (5) and the battery unit (5') as well as the switching of the multi-way valves (21, 22, 23, 24) of the primary and secondary cooling circuits (2, 4) are carried out as a function of an ambient temperature and an operating state of the battery unit (5'), wherein the battery unit (5') is operated in a discharging mode when the electric drive unit (5) has a driving effect, and wherein the battery unit (5') is operated in a charging mode when the on-board charger (14) is connected or when the electric drive unit (5) has a braking effect.

15. Cooling system according to claim 14, characterized in that the multi-way valves (21, 22, 23, 24) in a first operating mode, in which the ambient temperature is at least 15° C and the battery unit (5') is operated in discharge mode, are switched such that the primary and the secondary cooling circuit (2, 4) are operated independently of one another and in isolation, wherein the primary cooling circuit (2) flows through all individual components of the electric drive unit (5) and the heat exchanger (17) during cooling, and wherein the secondary cooling circuit (4) during cooling the refrigeration system (19), the Distribution elements (11), the heat exchangers (16) and the battery unit (5').

16. Cooling system according to claim 14, characterized in that the multi-way valves (21, 22, 23, 24) are switched in a second operating mode, in which the ambient temperature is less than 15° C and the battery unit (5') is operated in discharge mode, such that the primary and the secondary cooling circuit (2, 4) are operated in combination in connection with one another, wherein the combined cooling circuit (2, 4) flows through all the individual components of the electric drive unit (5) and the heat exchanger (17) of the primary cooling circuit (2) as well as the distributor elements (11), the heat exchangers (16) and the battery unit (5') of the secondary cooling circuit (4) during cooling.

17. Cooling system according to claim 14, characterized in that the multi-way valves (21, 22, 23, 24) are switched in a third operating mode, in which the ambient temperature is at least 20° C and the battery unit (5') is operated in charging mode, such that the primary and the secondary cooling circuit (2, 4) are operated independently of one another and in isolation, wherein the primary cooling circuit (2) flows through the on-board charger (14) and the heat exchanger (17) during cooling, and wherein the secondary cooling circuit (4) flows through the refrigeration system (19), the distribution elements (11), the heat exchangers (16) and the battery unit (5') during cooling.

18. Cooling system according to claim 14, characterized in that the multi-way valves (21, 22, 23, 24) are switched in a fourth operating mode, in which the ambient temperature is less than 20° C and the battery unit (5') is operated in charging mode, such that the primary and the secondary cooling circuit (2, 4) are operated in combination in connection with one another, wherein the combined cooling circuit (2, 4) flows through the on-board charger (14) and the heat exchanger (17) of the primary cooling circuit (2) as well as the distributor elements (11), the heat exchangers (16) and the battery unit (5') of the secondary cooling circuit (4) during cooling.

19. Cooling system according to one of claims 14 to 18, characterized in that the second multi-way valve (22) of the primary cooling circuit in the discharge mode of the Battery unit (5') is connected in such a way that it forms a bypass circuit for the on-board charger (14) and prevents a flow of coolant into the coolant channel of the on-board charger (14).

20. Cooling system according to one of claims 14 to 18, characterized in that the second multi-way valve (22) of the primary cooling circuit (2) and an additional check valve (6) are switched in the charging mode of the battery unit (5') such that the electric drive unit (5) is isolated from the primary cooling circuit (2) and is not flowed through by the coolant.

21. Cooling system according to one of the preceding claims, characterized in that the refrigeration system (19) comprises a PTC heating element for preconditioning the battery unit (5'), wherein the battery unit (5') can be tempered to an operating temperature above 0°C by the PTC heating element in the secondary cooling circuit (4) if the ambient temperature of the cooling system is less than 0°C before the start of charging of the battery unit (5').

22. Method for operating the cooling system (10) according to one of the preceding claims.

23. Commercial vehicle, with a cooling system (10) according to one of claims 1 to 21, characterized in that the commercial vehicle is formed by a combination of a tractor and a trailer coupled thereto with at least one, preferably with three trailer axles, wherein the trailer has the electric drive unit (5) and the battery unit (5'), and wherein the cooling system (10) is provided on the electrified trailer.

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