DE102020106320A1 - Method for operating an electrical drive system of a trailer vehicle of a towing vehicle-trailer vehicle combination as well as an electrical drive system - Google Patents

Abstract

The invention relates to a method for operating an electric drive system (11) of a trailer vehicle (3) of a towing vehicle-trailer vehicle combination (1), consisting of a towing vehicle (2) and the trailer. The trailer has a trailer axle (17c, 17d, 17e), a pneumatic or hydraulic trailer brake system (9) with a trailer friction brake (23, 24, 25) on the trailer axle and an electronic trailer brake system (10) with which the trailer brake system can be controlled. The towing vehicle has a towing vehicle axle (17a, 17b), an internal combustion engine (19), a pneumatic or hydraulic towing vehicle brake system (7) with a towing vehicle friction brake (21, 22) on its towing vehicle axle, optionally a permanent brake (18) and an electronically controlled towing vehicle braking system (8) ) on. The towing vehicle brake system and the optional permanent brake can be controlled by means of the towing vehicle brake system. The tractor-trailer combination has a data bus system (4, 5, 6) with which the electric drive system (11) and the electronically controlled brake systems (8, 10) are connected. The drive system of the trailer vehicle has an electrical machine (12) that can be operated as a motor or generator, a rechargeable electrical energy store (16), a battery management system (14) for monitoring and protecting the electrical energy store and an inverter (13) for controlling the electrical machine on. The electric drive system (11) is controlled by the electronically controlled trailer brake system (10).

Description

The invention relates to a method for operating an electric drive system of a trailer vehicle of a towing vehicle-trailer vehicle combination, consisting of a towing vehicle and the trailer vehicle. The trailer vehicle has a trailer vehicle axle, a pneumatic or hydraulic trailer brake system with a trailer vehicle friction brake on the trailer vehicle axle and an electronically controlled trailer brake system. The trailer braking system can be controlled by means of the electronically regulated trailer braking system. The towing vehicle has a towing vehicle axle, an internal combustion engine, a pneumatic or hydraulic towing vehicle brake system with a traction vehicle friction brake on the towing vehicle axle, optionally a permanent brake, and an electronically controlled tractor braking system. The towing vehicle brake system and the optional permanent brake can be controlled by means of the electronically regulated towing vehicle brake system. The tractor-trailer combination has a data bus system, by means of which the electric drive system and the electronically controlled brake systems are connected. The drive system of the trailer vehicle has an electrical machine that can be operated as a motor or generator, a rechargeable electrical energy store, a battery management system for monitoring and protecting the electrical energy store, and an inverter for controlling the electrical machine. In addition, the invention relates to the said electrical drive system of the trailer vehicle and a tractor-trailer vehicle combination with such an electrical drive system.

Trailer vehicles with electrical drive systems, which convert braking energy into electrical energy in a recuperation mode, are known in various designs. Such electrical drive systems are installed, for example, in trailers of commercial vehicles, such as semi-trailers or drawbar trailers, or in trailers for passenger vehicle combinations. The electric drive systems can serve, for example, as an additional electric motor drive to support an internal combustion engine of the towing vehicle in order to reduce fuel consumption and pollutant emissions. It is also possible that such an electrical drive system is only effective as a recuperation device, which drives an electrical machine as a generator for charging an electrical energy store in a recuperation mode in order to generate electrical energy for supplying electrically operated units, such as a cooling unit in a refrigerated vehicle, or to provide other electrical consumers.

the DE 10 2016 003 356 A1 shows a trailer of a towing vehicle-trailer combination. The trailer vehicle is a refrigerated vehicle with an electrically operated cooling unit. The towing vehicle and the trailer are each equipped with a pneumatic brake system and an electronic brake system each. The electronic braking system of the trailer vehicle has a recuperation device with an electrical machine and an electrical energy store. The two pneumatic brake systems are pneumatically connected to one another via a supply pressure coupling and a brake control pressure coupling. The two electronic brake systems are connected to one another via a data bus system. The towing vehicle also has a retarder as an additional brake. When a deceleration is requested by the towing vehicle, for example when the retarder is activated, the electronic brake system controls the recuperation device in the trailer to carry out a recuperation operation, the braking torque of the recuperation device being fully included in the control of the service brake, so that a resulting braking torque of the Service brake is a requested total braking torque minus the recuperation braking torque.

From the WO 2019/179 866 A1 a control device for controlling a mechanical power output and / or a mechanical power consumption of an electrical machine in a vehicle trailer is known. The electrical machine is coupled to at least one vehicle wheel in order to be able to convert mechanical rotational power at the wheel and electrical power at the electrical machine into one another. The control takes place as a function of a current driving state of a towing vehicle pulling the trailer.

The electrical power of the electrical drive system is provided by a rechargeable electrical energy store, a drive battery. Today's drive batteries are mostly made up of a battery pack with several cells in nickel-metal hydride technology or in lithium-ion technology. Typical performance values for such drive batteries are voltages of 60 V or more and electrical outputs of 50 kW or more.

The electrical energy storage device is charged by recuperation when the vehicle is braked actively or passively. In order to gain as much electrical energy as possible, the maximum possible recuperation power of the electrical drive system should be used. The maximum possible recuperation performance is the greatest possible electrical power that the electrical drive system can convert during recuperation and that can be absorbed by the energy store. It is limited by the specifications of the drive battery and the electrical machine. Ideally, this limit should be optimally used. On the other hand, the drive battery must not be overloaded during recuperation in order to reliably avoid irreversible damage, which can lead to a shortening of the service life or even to the destruction of the battery. Therefore, there is usually a battery management system that records the battery current, the battery voltage of the individual cells and the entire battery, the internal battery resistance and the temperature and transmits it to an electronic controller via a data bus system. This electronic control adjusts the battery current. The battery management system uses the current cell voltage and the internal battery resistance to determine a maximum possible charging current and, from this, the current maximum possible charging power of the battery. In the event of imminent overheating or when leaving a safe operating window (over- or undervoltage), the current flow to the battery is interrupted by a control unit or the battery management system.

In order not to overload the drive battery during recuperation or to safely avoid an emergency shutdown or battery damage, the mechanical power of the electrical machine must be limited in such a way that the electrical power generated does not exceed the permissible charging power of the battery. The mechanical power of the electrical machine results from the torque applied to a rotor of the electrical machine and the current machine speed. The power of the electrical machine is regulated via a torque specification. Due to power losses when converting mechanical energy into electrical energy due to the efficiency of the individual components of the drive - which are: the efficiency of the electrical machine, an inverter, an electrical intermediate circuit between the battery and the electrical machine, as well as a transmission that may be interposed in the power flow - is in Generator operation of the electrical machine, the mechanical power of the electrical drive system is always greater than the electrical power generated by energy conversion.

The problem is that all the efficiencies of all individual components in the efficiency chain of the electric drive system would have to be precisely known at all times in order to be able to adjust the mechanical and thus the electric power of the electric machine in such a way that the permissible charging power of the battery is reached, but not exceeded will. However, the efficiency of the electric drive system is not constant, but depends, among other things, on the operating state of the battery (state of charge [SOC; State of Charge], state of aging [SOH; State of Health], cell temperature)). A sufficiently precise determination of the efficiency at every operating point of the battery is hardly possible. The optimal torque requirement for the electrical machine is therefore not known. On the other hand, if the drive battery is overloaded, the generator operation of the electric machine may have to be unexpectedly switched off in an emergency, which of course should be avoided. In the worst case, the drive battery could also be destroyed.

After all, it is disadvantageous that in the known electrical drive systems and methods for their control, the electrical energy storage device is generally protected, but the recuperation operation is not optimally used for storing the recovered electrical energy.

Against this background, the invention is based on the object of presenting a method for operating an electrical drive system with an electrically chargeable energy storage device, with which a more effective and at the same time operationally reliable recuperation operation is achieved when charging the energy storage device. In addition, an electrical drive system is to be presented on which the above-mentioned method can be operated. The method and the electric drive system should be able to be carried out or used in particular on a trailer vehicle.

This object is achieved with a method or with an electric drive system which has the features of the independent claims. Advantageous refinements and developments of the invention are defined in the respectively assigned dependent claims.

The invention is based on the knowledge that it is possible in an electrical drive system of a vehicle with an electronically controlled braking system, in an electrical switching and control circuit with an electrical machine, an inverter and an electrical energy store and additionally with a direct current regulator, in cooperation with the electronically controlled braking system to regulate a maximum possible and permissible charging power of the energy storage device with simultaneous protection against overload in a recuperation mode of the drive system.

The invention therefore initially relates to a method for operating an electrical Drive system of a trailer vehicle of a towing vehicle-trailer combination, consisting of a towing vehicle and the trailer. The trailer vehicle has a trailer vehicle axle, a pneumatic or hydraulic trailer brake system with a trailer vehicle friction brake on the trailer vehicle axle and an electronically controlled trailer brake system. The trailer braking system can be controlled by means of the electronically regulated trailer braking system. The towing vehicle has a towing vehicle axle, an internal combustion engine, a pneumatic or hydraulic towing vehicle brake system with a traction vehicle friction brake on the towing vehicle axle, optionally a permanent brake, and an electronically controlled tractor braking system. The towing vehicle brake system and the optional permanent brake can be controlled by means of the electronically regulated towing vehicle brake system. The tractor-trailer combination has a data bus system, by means of which the electric drive system and the electronically controlled brake systems are connected. The drive system of the trailer vehicle has an electrical machine that can be operated as a motor or generator, a rechargeable electrical energy store, a battery management system for monitoring and protecting the electrical energy store, and an inverter for controlling the electrical machine.

To solve the process-related problem, the invention initially provides that the electric drive system of the trailer vehicle is controlled by the electronically regulated trailer brake system. In this case, the electrical drive system of the trailer vehicle is primarily controlled in recuperation mode, in order to convert braking energy into electrical energy and to charge the electrical energy storage device in generator mode of the electrical machine. The electrical energy is used to support the internal combustion engine with an additional electric motor drive power and / or to supply electrical consumers of the towing vehicle-trailer combination. With the help of a DC controller integrated in the electric drive system of the trailer vehicle and the inverter, a maximum permissible or maximum possible electric charging power of the electric energy storage device specified via the data bus system by the battery management system is regulated and at least almost maintained at all times. If necessary, the optionally available sustained-action brake is activated secondarily and the towing vehicle brake system and / or the trailer brake system are activated secondarily in order to achieve a requested braking torque.

In the following, a torque request is understood to mean the value of a requested torque. Alternatively, an inverter can also be referred to as an inverter. The phrase “at least almost complied with at all times” means that the stated goal will be achieved, as far as this is physically and technically possible.

An electrical drive system is understood to mean a system in which the electrical energy recovered through recuperation can be used not only to drive vehicle wheels, but also to feed electrical auxiliary consumers via an electrical energy store. In this respect, the electric drive system can alternatively also be called a recuperation device. Retarder brakes in a motor vehicle are, as mentioned above, known per se. They can be designed, for example, as an engine brake or as a hydrodynamic retarder.

According to the features of claim 1, the invention accordingly proposes to control the electric drive system of the trailer vehicle by means of the electronically controlled trailer brake system. The electric machine is operated as a generator or as a motor, depending on the driving situation, and it is controlled in coordination with the operation of any permanent brake, such as a retarder, and in coordination with the operation of the pneumatic or hydraulic brake systems of the towing vehicle and the trailer vehicle .

In recuperation mode, the electric machine is operated as a generator, the braking power of the generator being used first before the retarder and the friction brakes are used to further brake the vehicle if the braking power of the generator is insufficient. The recovered braking energy is stored as electrical energy in the energy storage unit according to the conversion efficiency and made available by the energy storage unit in the vehicle.

The electric drive system of the trailer vehicle is advantageously controlled with the help of a control of the direct current by an additionally arranged direct current regulator integrated in the electric drive system when charging the energy storage device in such a way that it is ensured at all times that the maximum possible charging power of the energy storage device is exhausted as completely as possible. As a result, the conversion of kinetic energy into electrical energy is maximized and, as a result thereof, the conversion of kinetic energy into thermal energy, for example in the retarder and / or in the wheel brakes, is minimized.

According to a further developed embodiment of the invention, it can be provided for an advantageous charge control of the energy storage device that, in the event of a deceleration of the journey of the towing vehicle / trailer vehicle combination requested by a driver's request or by an assistance system, a braking torque of at least one vehicle wheel necessary for the requested deceleration is determined . A torque request for the electrical machine corresponding to this wheel braking torque is then calculated and transmitted to the inverter. If necessary, a map stored in a data memory is used for this purpose. A current mechanical power requirement for the electrical machine is then determined from the current speed of the electrical machine and the value of the torque requirement. The mechanical power requirement of the electrical machine is then compared with the maximum permissible electrical charging power of the electrical energy storage device specified by the battery management system. In the event that the mechanical power requirement on the electrical machine is above the maximum permissible electrical charging power of the electrical energy store, an optimization cycle is then started and run through. First, the value of the current mechanical power of the electrical machine is determined and this is limited to the maximum permissible electrical charging power of the electrical energy store. The reduced torque value resulting from the limited current mechanical power of the electrical machine is then transmitted to the inverter as a new torque request. The charging power of the electrical machine is then regulated by means of the DC regulator in such a way that the lowered torque requirement for the electrical machine transmitted to the inverter increases again gradually until the maximum permissible electrical charging power of the electrical energy store is reached.

Accordingly, when the driver or a braking assistance system requests a deceleration, a braking torque Mbrems corresponding to the deceleration request is requested on at least one vehicle wheel by means of the electronically controlled trailer braking system. A torque request is made with the braking torque Mbrems M _beg intended for the electrical machine. If necessary, a transmission interposed in the power flow is taken into account by adding the braking torque Mbrems to the torque request by means of a stored transmission characteristic field M _beg is converted. The value of the torque request M _beg is sent to the inverter or used to control it. Before the inverter this torque M _beg can be set on the electrical machine, it must be ensured that the electrical energy storage device is not overloaded when the electrical machine is subsequently operated as a generator. Therefore, the current speed is used first n of the electrical machine and the value of the torque request M _beg into a requested mechanical performance P _{mech, beg} of the electrical machine with P _{mech, anf} = 2π · n · M _{anf is} calculated.

Which results from the charging voltage U _loading and the charging current I _load The resulting electrical charging power P _load = U _load · I _load , with which the energy store is charged, depends on the mechanical power Pmech of the electrical machine in generator mode. Since the conversion of mechanical energy into electrical energy is physically subject to losses, the electrical power generated is P _el according to the formula P _el = P _mech · η due to the efficiency η of the electrical drive system is always smaller (η <1) than the mechanical power Pmech.

The efficiency η varies, however, and is in particular temperature-dependent and can therefore not be easily determined during vehicle operation. At most, a rough estimate would be possible. The electrical charging power actually generated during recuperation P _el therefore cannot be precisely calculated in advance. Therefore, in practical operation, the mechanical power Pmech of the electrical machine has hitherto been limited to be on the safe side, preferably to the maximum possible charging power P _{load, max} of the electrical energy store, although the mechanical power Pmech is always significantly greater. Consequently, the electrical power generated in the recuperation mode is P _el always less than the maximum possible charging power P _{load, max} of the electrical energy store; so the inequality P _el <P _{lade, max} .

It is therefore often charging power in vehicle operation P _load not used because the mechanical power Pmech of the electrical machine is unnecessarily greatly reduced, whereby a considerable amount of recuperation energy is converted into frictional heat through the use of the service brake and / or the retarder. The use of a possibly incorrectly estimated efficiency η _schnätz for the regulation of the electrical machine cannot resolve this dilemma and would rather lead to an undefined charging operation. Thus, with the _{help of} an estimated efficiency η estimate and a correspondingly weaker reduction in the mechanical power Pmech of the electrical machine, on the one hand the unnecessary losses could be reduced, but on the other hand an overload of the energy store could not be ruled out.

The invention solves this problem. For this purpose, it is first checked whether the requested mechanical power Pmech of the electrical machine is above the maximum possible charging power P _{load, max} of the energy storage system. If this is the case, the initially requested mechanical power Pmech is increased to the maximum charging power P _{load, max} limited. As a result, the torque requirement is M _red from the inverter according to the equation M _red = M _Anf · P _{load, max} / P _{mech, Anf} with P _{mech, beg} reduced as the requested mechanical power at the beginning of the process cycle. A DC regulator now regulates the DC voltage U _loading and the direct current I _load of the electric machine in generator mode to the maximum possible or the maximum permissible charging power P _{load, max} by continuously adapting the torque request, with the torque mouth thus gradually increasing the braking effect of the electric machine, with the original torque request M _beg is expediently set as an upper limit.

In other words, the invention proposes an operating strategy for electric drives in vehicle trailers in which a direct current regulator is used in order to recuperate as much kinetic energy as possible into electrical energy. For this purpose, with the help of information that is available on a data bus of the vehicle, cyclical comparisons of a maximum permissible charging current, a current charging current and a requested mechanical braking power of the drive are evaluated in an electronic control circuit, and the charging parameters of the electrical energy storage device are continuously optimized on the basis of this comparison.

According to a further development of the method according to the invention, the temperature of the electrical machine and the inverter of the electrical drive system can be continuously monitored, and that the torque requirement on the electrical machine is reduced by a specified factor by means of the inverter when a specified temperature limit is exceeded. Accordingly, the inverter can also be designed to reduce the torque demand on the electric machine in the event of an impending overheating of the electrical machine and / or the inverter itself. This takes place independently of the regulation of the torque demand by the direct current regulator. This ensures that the electrical machine and the inverter cannot be thermally overloaded when optimizing the electrical charging power of the electrical energy store.

The method described can be operated on an electric drive system of a trailer vehicle of a towing vehicle-trailer vehicle combination, this comprising a towing vehicle and the trailer vehicle.

The trailer vehicle has a trailer vehicle axle, a pneumatic or hydraulic trailer brake system with a trailer vehicle friction brake on the trailer vehicle axle and an electronically controlled trailer brake system. The trailer braking system can be controlled by means of the electronically regulated trailer braking system. The towing vehicle has a towing vehicle axle, an internal combustion engine, a pneumatic or hydraulic towing vehicle brake system with a traction vehicle friction brake on the towing vehicle axle, optionally a permanent brake, and an electronically controlled tractor braking system. The towing vehicle brake system and the optional permanent brake can be controlled by means of the electronically regulated towing vehicle brake system. The tractor-trailer combination has a data bus system, by means of which the electric drive system and the electronically controlled brake systems are connected. The drive system of the trailer vehicle has an electrical machine that can be operated as a motor or generator, a rechargeable electrical energy store, a battery management system for monitoring and protecting the electrical energy store, and an inverter for controlling the electrical machine.

According to the invention, the electrical drive system of the trailer vehicle has a direct current regulator, by means of which a predetermined maximum permissible or maximum possible electrical charging power of the electrical energy store can be set and at least almost maintained at any point in time in recuperation mode. The DC regulator is or can be actively connected to the electronically controlled trailer braking system.

Here, too, the phrase “at least almost” makes it clear that the aforementioned optimal target achievement is only possible to the extent that it is physically and technically achievable in the specific application.

With the help of a direct current regulator, the maximum possible or maximum permissible electrical charging power of the energy store (target value) can be continuously compared with the actual charging power (actual value) during recuperation and the torque request (manipulated variable) transmitted to the inverter can be adjusted so that the maximum possible or maximum permissible Charging power is regulated.

According to one embodiment of the invention it is provided that the direct current regulator is designed as a PI regulator. PI controllers are known and are available on the market as continuous linear controllers with a fast response behavior and high control accuracy at the same time. It has been found that such a PI controller is particularly advantageously suitable for optimizing the electrical charging power of an electrical energy store in the recuperation mode of an electrical drive system.

Finally, the invention relates to a towing vehicle / trailer vehicle combination with an electric drive system as described above. The electric drive system can be operated to carry out a method as described above.

• 1 eine schematische Ansicht einer Zugfahrzeug-Anhängefahrzeug-Kombination mit einem Blockschaltbild eines elektrischen Antriebssystems eines Anhängefahrzeugs gemäß der Erfindung, und
• 2 ein Flussdiagramm des erfindungsgemäßen Verfahrens zum Betrieb eines elektrischen Antriebssystems gemäß 1.

The invention is explained in more detail below with reference to an embodiment shown in the accompanying drawing. In the drawing shows

• 1 a schematic view of a tractor-trailer vehicle combination with a block diagram of an electrical drive system of a trailer vehicle according to the invention, and
• 2 a flowchart of the method according to the invention for operating an electric drive system according to FIG 1 .

Accordingly, the in 1 shown and designed as an articulated vehicle towing vehicle-trailer vehicle combination 1 a towing vehicle designed as a two-axle tractor unit 2 as well as a trailer vehicle designed as a three-axle semi-trailer 3 on.

The towing vehicle 2 has a drive train with an internal combustion engine 19th and a vehicle transmission (not shown) for driving a driving tractor axle 17b in a known construction. The two vehicles 2 , 3 are mechanically connected or connectable to one another in the usual way via a fifth wheel. In addition, there is a data connection 4th via a so-called brake CAN bus according to ISO 7638 between a first CAN bus 5 of the towing vehicle 2 according to ISO 11992 and a second CAN bus 6th of the trailer vehicle 3 provided in accordance with ISO 11992-2.

The towing vehicle 2 is with a pneumatic or hydraulic towing vehicle brake system 7th fitted. The towing vehicle brake system 7th has towing vehicle friction brakes 21 , 22nd on the two towing vehicle axles 17a , 17b of the towing vehicle 2 as well as an electronically controlled towing vehicle braking system 8th to control the towing vehicle friction brakes 21 , 22nd on. The trailer vehicle is analogous to this 3 with a pneumatic or hydraulic trailer braking system 9 fitted. The trailer braking system 9 has trailer friction brakes 23 , 24 , 25th on the three trailer axles 17c , 17d , 17e of the trailer vehicle 3 as well as an electronically controlled trailer braking system 10 for controlling the trailer vehicle friction brakes 23 , 24 , 25th on. The towing vehicle friction brakes 21 , 22nd act in a known manner on vehicle wheels 30th , 31 of the towing vehicle 2 . The trailer friction brakes act accordingly 23 , 24 , 25th on vehicle wheels 32 , 33 , 34 of the trailer vehicle 3 .

Correspondingly consist - in 1 not shown - pneumatic or hydraulic connections between the two vehicles 2 , 3 for a brake control pressure (yellow coupling head) and for a supply pressure (red coupling head). The towing vehicle 2 also has a permanent brake designed here as a retarder 18th as an additional brake to the one with the friction brakes 21 , 22nd , 23 , 24 , 25th equipped pneumatic or hydraulic towing vehicle brake system 7th (Service brake).

The electronically controlled towing vehicle braking system 8th internally instructs - in 1 not shown - first electronic control unit, which is connected to the CAN bus 5 of the towing vehicle 2 connected. The one in the towing vehicle 2 arranged retarder 18th is next to the towing vehicle brake system 7th (Service brake) by means of the electronically controlled towing vehicle brake system 8th via the CAN bus 5 of the towing vehicle 2 controllable.

The electronically controlled trailer braking system 10 internally instructs - in 1 Not shown - second electronic control unit, which is connected to the CAN bus 6th of the trailer vehicle 3 connected. Furthermore, the trailer vehicle 3 an electric drive system 11 on. The electric propulsion system 11 is functional in the electronically controlled trailer braking system 10 integrated. The electric drive system 11 has at least one electrical machine 12th on, which in this embodiment example with one of a front side of the trailer vehicle 3 seen rear, here - from the front of the trailer 3 counted off - third trailer axle 17e for driving vehicle wheels 34 the rear trailer axle 17e is connected to the drive. As the "front" of the trailer vehicle 3 here is the one when coupled to the towing vehicle 2 facing side of the trailer vehicle 3 designated.

The electric machine 12th is through an inverter 13th , a battery management system 14th and a DC regulator designed here as a PI regulator 15th with one here as a drive battery trained rechargeable electrical energy storage 16 electrically connected and, if necessary, operated as a motor or generator. The electric machine 12th , the inverter 13th , the battery management system 14th , the DC regulator 15th and the electrical energy storage 16 are all the electric propulsion system 11 of the trailer vehicle 3 assigned. The inverter 13th , the battery management system 14th and the DC regulator 15th can, as shown, in their own control unit 20th of the electric drive system 11 be integrated.

In the present case, there is only an electrical machine 12th provided, the two vehicle wheels of the third trailer axle via a differential gear (not shown here) 17e can drive or generate mechanical energy in recuperation mode. Of these two vehicle wheels is in the side view according to FIG 1 only one vehicle wheel 34 visible. Alternatively, any driving vehicle wheel 34 this third trailer axle 17e and / or each driving vehicle wheel 32 , 33 another trailer axle 17c , 17d of the trailer vehicle 3 be assigned its own electrical machine. In this case, each of the electrical machines is preferably assigned its own inverter for regulating it.

• Über den CAN-Bus 6 des Anhängefahrzeugs 3 erhält das elektronisch geregelte Anhängerbremssystem 10 beziehungsweise dessen Steuergerät eine Anforderung zur Erzeugung eines bestimmten, fahrsituationsabhängigen Bremsmoments M_brems . Dieses Bremsmoment Mbrems kann durch Betätigen eines mit dem elektronisch geregelten Zugfahrzeugbremssystem 8 verbundenen Bedienelements der Zugfahrzeugbremsanlage 7 oder der Dauerbremse 18 (Bremspedal, Bedienhebel) ausgelöst werden und ist mit einem bestimmten Bremssteuerdruck korreliert. Das elektronisch geregelte Anhängerbremssystem 10 sendet ein diesbezügliches Signal an das elektrische Antriebssystem 11 zur Einschaltung der elektrischen Maschine 12 in den Generatorbetrieb.

In a recuperation mode, the electric machine 12th operated as a generator. The electrical energy generated in the process is stored in the electrical energy store 16 saved. The electronically controlled trailer braking system 10 works with the electric drive system 11 as follows:

• Via the CAN bus 6th of the trailer vehicle 3 receives the electronically controlled trailer braking system 10 or its control unit a request to generate a specific, driving situation-dependent braking torque M _brake . This braking torque Mbrems can be activated by actuating one of the electronically controlled towing vehicle braking systems 8th connected control element of the towing vehicle brake system 7th or the retarder 18th (Brake pedal, operating lever) and is correlated with a specific brake control pressure. The electronically controlled trailer braking system 10 sends a signal to this effect to the electric drive system 11 to switch on the electrical machine 12th in generator mode.

The trailer braking system 10 would usually also use the pneumatic or hydraulic trailer braking system 9 , i.e. the service brakes of the trailer vehicle 3 , control with the brake control pressure. The braking torque of the activated retarder 18th and the trailer braking system 9 then add up to one through the electric machine 12th regenerative braking torque generated as a generator to a total braking torque, which is that of the towing vehicle braking system 8th the transmitted braking request.

To in the process of decelerating the vehicle 1 To recuperate as much kinetic energy as possible, namely around the electrical energy storage 16 with the maximum possible charging power P _{load, max} of the electrical energy storage 16 In comparison to the prior art, at least initially only the recuperation operation of the electrical machine is required 12th driven to convert the braking request, ie the desired deceleration of the motor vehicle, into an actual deceleration of the vehicle 1 to implement. In this case, a control method is used, by means of which a maximum possible charging power is achieved through the interaction according to the invention of all components of the device P _{load, max} of the electrical energy storage 16 is regulated without the energy storage 16 to harm.

the 2 shows a flow chart with seven function blocks F1 to F7 for the execution of a method according to the invention. The method accordingly starts in a first function block F1. The electronically controlled trailer braking system 10 has to do this from the towing vehicle braking system 8th received a delay request. The electric machine 12th is switched on and is in generator mode for recuperation of braking energy.

According to the function block F2, a desired braking torque Mbrems corresponding to the brake control pressure is then transmitted to the electrical machine 12th requested torque M _beg converted. A query follows in function block F3, in which the current speed n of the electric machine 12th measured and the torque requirement M _beg into a requested mechanical performance P _{mech, beg} of the electrical machine according to P _{mech, anf} = 2π · n - M _{anf is} converted. The requested service P _{mech, beg} is then with a specified maximum possible charging power P _{load, max} of the energy storage 16 compared. This maximum possible charging power P _{load, max} of the energy storage 16 results from the equation P _{load, max} = U _{load, max} · I _{load, max} , where U _{load, max} the maximum possible charging voltage and I _{load, max} the maximum possible charging current of the electrical energy storage device 16 are.

Is the requested mechanical performance P _{mech, beg} of the electric machine 12th less than the maximum possible charging power P _{load, max} , the electrical machine can with a torque according to function block F4 M. be charged, which dem requested torque M _beg corresponds to the generated electrical charging power P _load is always below the permissible maximum. This applies at least until the inverter 13th a reduction due to the threat of overheating of the machine 12th initiates.

Is the requested mechanical performance P _{mech, beg} of the electric machine 12th but greater than the maximum possible charging power P _{load, max} of the electrical energy storage 16 , according to function block F5, the mechanical power P _{mech, beg} of the electric machine 12th to the maximum possible charging power P _{load, max} of the electrical energy storage 16 according to the equation P _{mech, anf} = P _{load, max} . The torque request is then made in function block F6 M _beg to the inverter 13th according to M _red = M _Anf · P _{load, max} / P _{mech, anf lowered} to a reduced torque requirement Mred.

Because the current values of the charging voltage U _loading and the charging current I _load through the battery management system 14th measured and on the CAN bus 6th are available, the DC regulator can now 15th according to function block F7 the electrical charging power P _load by regulating the charging current I _load and / or the charging voltage U _loading gradually increase to the maximum possible or maximum permissible value. This is done by applying the torque to the electrical machine 12th with reduced values of the torque requirement M _red is gradually increased (symbolized in function block F7 by reference numerals M _red ↑). The torque originally requested serves as the upper limit for this process M _beg , from which the inequality M _red ≤ M _anf results. Otherwise, a higher braking effect than desired could be generated. With regard to the charging power, this means that the current charging power P _{lade, current} is always less than or at most equal to the maximum charging power P _{mech, max} , which results in the inequality P _{load, currently} ≤ P _{mech, max} . This reliably prevents damage to the electrical energy store.

Only the proportion of the desired total braking torque that is used when regulating the charging power P _load that by the electric machine 12th generated braking torque is applied by operating the service brakes and the retarder. Using the DC regulator 15th is thus achieved that through the braking effect of the electrical machine operating in generator mode 12th maximum amount of electrical energy generated and stored in the electrical energy store 16 is saved. This ensures that the electric drive system 11 or its components cannot be overloaded.

List of reference symbols

1

Towing vehicle-trailer combination

2

Towing vehicle

3

Trailer vehicle

4th

Electrical data connection, data bus system (brake CAN bus)

5

CAN bus of the towing vehicle

6th

CAN bus of the trailer vehicle

7th

Pneumatic / hydraulic towing vehicle brake system with friction brakes

8th

Electronically controlled towing vehicle braking system

9

Pneumatic / hydraulic trailer brake system with friction brakes

10

Electronically controlled trailer braking system

11

Electric drive system of the trailer vehicle

12th

Electric machine (motor / generator)

13th

Inverter

14th

Battery management system

15th

DC regulator

16

Electrical energy storage, drive battery

17a

First towing vehicle axle

17b

Second towing vehicle axle

17c

First trailer axle

17d

Second trailer axle

17e

Third trailer axle

18th

Permanent brake, retarder

19th

Internal combustion engine

20th

Control unit of the electric drive system

21

First traction vehicle friction brake

22nd

Second traction vehicle friction brake

23

First trailer friction brake

24

Second trailer friction brake

25th

Third trailer friction brake

30th

Vehicle wheel on the first tractor axle

31

Vehicle wheel on the second tractor axle

32

Vehicle wheel on the first trailer axle

33

Vehicle wheel on the second trailer axle

34

Vehicle wheel on the third trailer axle

F1 - F7

Function blocks

Ilade

Charging current of the energy storage

Ilade, max

Maximum charging current of the energy storage

M.

Torque

Manf

Torque requirement

Mbrems

Braking torque

Mred

Reduced torque requirement

n

Speed of the electric machine

Pel

Electric power of the electric machine

Plade

Electrical charging power of the energy storage

Plade, currently

Reduced current value of the electrical charging power

Tray, max

Maximum possible or permissible charging power of the energy storage

Pmech, beg

Required mechanical power of the electrical machine

Ulade

Charging voltage of the energy storage

Ulade, max

Maximum charging voltage of the energy storage

η

Efficiency

QUOTES INCLUDED IN THE DESCRIPTION

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

Patent literature cited

• DE 102016003356 A1 [0003]
• WO 2019/179866 A1 [0004]

Claims (6)

Method for operating an electric drive system (11) of a trailer vehicle (3) of a towing vehicle-trailer vehicle combination (1), consisting of a towing vehicle (2) and the trailer vehicle (3), wherein - the trailer vehicle (3) - a trailer vehicle axle (17c , 17d, 17e), - a pneumatic or hydraulic trailer brake system (9) with a trailer vehicle friction brake (23, 24, 25) on the trailer axle (17c, 17d, 17e) and - an electronically controlled trailer brake system (10), by means of which the trailer brake system ( 9) is controllable, has - the tractor (2) - a tractor axle (17a, 17b), - an internal combustion engine (19), - a pneumatic or hydraulic tractor brake system (7) with a tractor friction brake (21, 22) on the tractor axle ( 17a, 17b), - optionally a permanent brake (18), and - an electronically controlled towing vehicle brake system (8), by means of which the towing vehicle brake system (7) and, if this is available, the optional permanent brake remse (18) are controllable, - the towing vehicle-trailer vehicle combination (1) has a data bus system (4, 5, 6), by means of which the electric drive system (11) and the electronically controlled trailer braking system (10) and the electronically controlled The towing vehicle braking system (8) are connected, and - the electrical drive system (11) of the trailer vehicle (3) - an electrical machine (12) that can be operated as a motor or generator, - a rechargeable electrical energy store (16), - a battery management system (14) for monitoring and protecting the electrical energy store (16) and - has an inverter (13) for controlling the electrical machine (12), characterized in that - the electrical drive system (11) of the trailer vehicle (3) by the electronically controlled trailer braking system ( 10) is controlled, wherein - in a recuperation mode, primarily the electric drive system (11) of the trailer vehicle (3) is controlled in order to i n a generator operation of the electrical machine (12) to convert braking energy into electrical energy and to charge the electrical energy store (16), Trailer vehicle combination (1) is used, - with the aid of a DC regulator (15) integrated in the electric drive system (11) of the trailer vehicle (3) and, by means of the inverter (13), one specified by the battery management system (14) via the data bus system (4) maximum permissible or maximum possible electrical charging power of the electrical energy storage device (16) is regulated and at least almost complied with at all times, and - if necessary, the optionally available retarder (18) and, secondarily, the towing vehicle brake system (7) and / or the trailer brake system (9) are controlled be to an at to achieve the required braking torque. Procedure according to Claim 1 , characterized in that in the case of a deceleration of the journey of the towing vehicle-trailer vehicle combination (1) requested by a driver's request or by an assistance system, the following steps are carried out by the electronically controlled trailer braking system (10): - Determination of at least a braking torque necessary for the requested deceleration a vehicle wheel (30, 31, 32, 33, 34), - calculating a torque request for the electric machine (12) corresponding to this braking torque, if necessary with the aid of a map stored in a data memory, and transmitting this torque request to the inverter (13), - Determining the current speed of the electrical machine (12) and determining a mechanical power requirement for the electrical machine (12) from the current speed and the torque requirement, - comparing the mechanical power requirement for the electrical machine (12) with the predetermined maximum z permissible electrical charging power of the electrical energy store (16), and - running through an optimization cycle in the event that the mechanical power requirement on the electrical machine (12) is above the maximum permissible electrical charging power of the electrical energy store (16), where - initially the value of the current mechanical power of the electrical machine (12) is determined and this is limited to the maximum permissible electrical charging power of the electrical energy store (16), - the reduced value of the torque to the inverter resulting from the limited current mechanical power of the electrical machine (12) (13) is transmitted as a new torque request, and - then the charging power of the electrical machine (12) is regulated by means of the direct current regulator (15) in such a way that the reduced torque request transmitted to the inverter (13) is returned to the electrical machine (12) gradually increased until the maximum permissible electrical charging power of the electrical energy store (16) is reached. Procedure according to Claim 1 or 2 , characterized in that the temperature of the electrical machine (12) and the inverter (13) of the electrical drive system (11) is permanently monitored, and that when a predetermined temperature limit value is exceeded, the torque demand on the electrical machine (12) by means of the inverter (13) is reduced by a predetermined factor. Electric drive system (11) of a trailer vehicle (3) of a towing vehicle-trailer vehicle combination (1), consisting of a towing vehicle (2) and the trailer vehicle (3), wherein - the trailer vehicle (3) - a trailer vehicle axle (17c, 17d, 17e ), - a pneumatic or hydraulic trailer brake system (9) with a trailer friction brake (23, 24, 25) on the trailer axle (17c, 17d, 17e) and - an electronically controlled trailer brake system (10), by means of which the trailer brake system (9) can be controlled - the towing vehicle (2) - a towing vehicle axle (17a, 17b), - an internal combustion engine (19), - a pneumatic or hydraulic towing vehicle brake system (7) with a towing vehicle friction brake (21, 22) on the towing vehicle axle (17a, 17b) - Optionally a retarder (18), and - an electronically controlled towing vehicle brake system (8), by means of which the towing vehicle brake system (7) and, if available, the optional retarder (18) can be controlled, up eist, and - the towing vehicle-trailer vehicle combination (1) has a data bus system (4, 5, 6) by means of which the electric drive system (11) and the electronically controlled trailer braking system (10) and the electronically controlled towing vehicle braking system (8) are connected - the electrical drive system (11) of the trailer vehicle (3) - an electrical machine (12) that can be operated as a motor or generator, - a rechargeable electrical energy storage device (16), - a battery management system (14) for monitoring and protecting the electrical system Energy storage device (16) as well as an inverter (13) for controlling the electric machine (12), characterized in that the electric drive system (11) of the trailer vehicle (3) has a direct current regulator (15), by means of which a predetermined maximum permissible or maximum possible electrical charging power of the electrical energy store (16) adjustable and for each Z eitpunkt is at least almost achievable, the direct current regulator (15) being operatively connected or operatively connectable to the electronically controlled trailer brake system (10). Electric drive system (11) according to Claim 4 , characterized in that the direct current regulator (15) is designed as a PI regulator. Towing vehicle-trailer vehicle combination (1), with an electric drive system (11) of a trailer vehicle (3), which according to one of the Claims 4 or 5 constructed and for performing a method according to the features of one of the Claims 1 until 3 is operable.

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