EP4355607A1

EP4355607A1 - Electrical drive system for a vehicle

Info

Publication number: EP4355607A1
Application number: EP22732562.8A
Authority: EP
Inventors: Sebastian Kratzer; Mouli Nikunz Karanam
Original assignee: MAN Truck and Bus SE
Current assignee: MAN Truck and Bus SE
Priority date: 2021-06-14
Filing date: 2022-06-13
Publication date: 2024-04-24
Also published as: DE102021115277A1; WO2022263347A1

Abstract

The invention relates to an electrical drive system for a vehicle, and to a vehicle with a drive system of this kind. The electrical drive system (100) comprises a high-voltage, direct-current circuit, HV-DC circuit (2); an alternating-current circuit, AC circuit (3); an AC/DC inverter (4) for coupling the HV-DC circuit (2) and the AC circuit (3); and a traction energy storage system (10) for providing electrical power for the HV-DC circuit (2). The traction energy storage system (10) comprises a plurality of electrical energy storage devices (11a, 11b, 11n), wherein each energy storage device (11a, 11b, 11n) comprises a plurality of cells (12) and an energy storage controller (13). In order to limit switch-on currents when switching on the traction energy storage system, a central precharging device (20) is provided or alternatively precharging circuits which are associated with the individual energy storage devices are provided, the central precharging device or precharging circuits comprising a pulse-width-modulated semiconductor assembly for limiting switch-on currents.

Description

Electrical drive system for a vehicle Description

The invention relates to an electric drive system for a vehicle and a vehicle with such a drive system.

Electric drive systems for vehicles known from practice usually include an AC circuit and a DC circuit, which are connected by at least one ACDC inverter. At least one electrical energy store is usually connected to the DC circuit. Various ancillary units can also be connected. Inverters and auxiliaries often have input capacitances on the DC circuit side.

When starting the vehicle, switching on the energy storage device is usually required, e.g. B. via the CAN data bus. Due to the high capacity and open-circuit voltage of the energy storage device and the low contact resistance in the DC circuit, short-circuit-type inrush currents would occur if the current were not limited. To prevent this, in the energy storage, z. B. in the battery, usually installed a pre-charging circuit, which limits the connection current via a pre-charging resistor.

Currently, just in electrically or at least partially electrically powered utility vehicles such. B. commercial vehicles, which are designed as battery electric vehicles (BEV), hybrid electric vehicles (HEV) or plug-in hybrid vehicles (PHEV), several Energiespei cher installed and parallel and / or serially connected to the DC circuit. As a result, a pre-charging circuit is often installed several times per vehicle. This leads to increased space requirements and costs.

It is an object of the invention to provide an improved pre-charging technique with which disadvantages of conventional pre-charging techniques can be avoided. The object of the invention is in particular to provide a more cost-efficient and/or space-optimized pre-charging technology for electric drive systems.

The object is solved by the features of the independent claims. Advantageous further developments are specified in the dependent claims and the description. In a general aspect, the invention relates to an electric drive system for a vehicle. The electric drive system includes a high-voltage DC voltage circuit, also referred to below as the HV-DC circuit for short, an AC voltage circuit, also referred to below as the AC circuit for short, and an AC/DC inverter for coupling the HV-DC circuit and AC circuit.

The electrical drive system also includes a traction energy storage system for providing electrical power for the HV-DC circuit. The traction energy storage system includes several electrical energy storage, z. B. several batteries. The multiple electrical energy stores can be connected to one another in parallel or in series. In this case, each energy store comprises a plurality of cells and an energy store controller. In other words, the traction energy storage system includes a multi-battery architecture made up of several built-in energy storage devices that are connected in parallel and/or in series to the HV-DC circuit.

The electric drive system can also include an electric machine that can be operated as a motor and as a generator and that serves as the electric drive motor of the vehicle. The AC/DC inverter can be designed in a manner known per se to control the electrical machine and, for this purpose, convert a DC voltage into AC voltage (or vice versa in the recuperative operating mode).

Furthermore, a pre-charging device is provided for limiting switch-on currents when the traction energy storage system is switched on.

According to a first aspect of the invention, the pre-charging device can be provided as a central pre-charging device, in particular as a central pre-charging circuit, which is designed to limit the connection currents when the traction energy storage system is switched on. A central pre-charging device is understood as meaning a pre-charging device which can limit the connection current of the entire traction storage system when it is switched on, so that a number of individual pre-charging circuits which are each assigned to one of the number of energy storage devices are not required. The central pre-charging device thus provides the pre-charging functionality for all energy stores of the traction energy storage system centrally at one point and/or through a circuit or assembly. In one embodiment, the central pre-charging device has a first separating device, hereinafter referred to as the main contactor, a second separating device, hereinafter referred to as the pre-charging contactor, and a pre-charging resistor, with a load output of the traction energy storage system being able to be connected to the HV-DC circuit using the main contactor and the pre-charging contactor can be switched off from this. Here, the pre-charging contactor and the pre-charging resistor are preferably arranged in a first path of the pre-charging device, which is parallel to a second path in which the main contactor is arranged. If required, the second path can be bridged by means of the pre-charging device by opening the main charging contactor in the second path and closing the pre-charging contactor in the first path. The pre-charging resistor limits the current. The current that occurs when the traction energy storage system is switched on depends on the pre-charging resistor.

A pre-charging circuit in the individual energy stores can thus be omitted. Accordingly, the space requirement and the costs for providing the pre-charging functionality can be advantageously reduced.

In an advantageous variant of this embodiment, the central pre-loading device is designed as a central pre-loading box, which preferably has its own housing. The pre-charge box is preferably arranged between the traction energy storage system and the rest of the DC circuit.

The electric drive system can also have a DC voltage converter (DC/DC converter), preferably in the form of a bidirectional DC/DC converter, a low-voltage DC voltage circuit, referred to below for short as an LV-DC circuit, and an LV-DC circuit Circularly arranged voltage source, e.g. B. have a battery. The low-voltage circuit can have a nominal voltage of 12 volts or 24 volts, for example. The voltage source arranged in the LV DC circuit thus provides a correspondingly low voltage - in contrast to the traction energy storage system in the HV DC circuit, which can provide a higher voltage in comparison to this.

In an alternative embodiment, the electric drive system in turn has the DC-DC converter described above, which couples the LV-DC circuit to the HV-DC circuit, and the voltage source arranged in the LV-DC circuit. According to this alternative embodiment, the central pre-charging device is not formed by a central pre-charging circuit comprising a pre-charging contactor and pre-charging resistor, but instead the pre-charging functionality is provided centrally by the DC/DC converter. For this purpose, the DC/DC is designed and/or is controlled to provide the pre-charging functionality and/or to pre-charge the HV-DC circuit in order to transfer energy from the LV-DC circuit to the HV-DC circuit. For this purpose, the DC/DC converter can be controlled accordingly by a control device, e.g. B. from a control device, which also controls the traction energy storage system. The traction energy storage system is preferably separated from the HV-DC circuit during pre-charging. This alternative embodiment thus also makes it possible for a pre-charging circuit to be omitted in the individual energy stores and for the installation space required and the costs for providing the pre-charging functionality to be advantageously reduced accordingly. A particular advantage of this embodiment is that an existing component, here the DC/DC converter, is used to provide the pre-charging functionality, so that additional components such as pre-charging contactors and pre-charging resistors can be dispensed with.

It has already been established above that a pre-charging functionality is provided centrally by means of the embodiments described above, so that a pre-charging circuit in the individual energy stores can thus be omitted. Correspondingly, according to a further aspect, the plurality of electrical energy stores of the traction energy store system can each have no pre-charging circuit. Alternatively or additionally, the traction energy storage system may not have a pre-charging circuit that is only assigned to one of the several electrical energy storage devices. In other words, the individual energy stores of the traction energy storage system each have no integrated pre-charging circuit and/or no pre-charging circuit is provided which is assigned to only one of the several electrical energy stores.

According to a second aspect of the invention, the object of the invention is achieved in that each of the multiple energy storage devices of the traction energy storage system has a pre-charging circuit instead of a conventional pre-charging circuit comprising a main contactor, pre-charging contactor and pre-charging resistor and/or is assigned its own pre-charging circuit, which Limiting inrush currents when the energy store is switched on includes a pulse-width-modulated semiconductor assembly connected in parallel to the main contactor of the energy store. A pulse width modulated (PWM) semiconductor device is a semiconductor device that can be operated in PWM mode in order to limit the current during precharging. The pre-charging takes place here via the PWM circuit in the form of the semiconductor assembly. Accordingly, the pre-charging contactor and the pre-charging deresistance in each of the energy stores are eliminated, which are instead replaced by the PWM circuit. This results in a significant miniaturization of the pre-charging circuit. Accordingly, both costs and weight can be saved. The semiconductor assembly can be power semiconductors, MOSFETs or similar. include, which can be controlled in PWM operation to set different currents. The semiconductor assembly can be variably switched between low-impedance and high-impedance, for example, in order to adjust, in particular to limit, the current from the respective energy store during precharging.

According to a further aspect, each of the multiple energy storage devices can comprise one or more interconnected cell modules and an energy storage controller in signal communication with the at least one cell module, and the at least one cell module can each comprise a plurality of interconnected storage cells and a cell module controller in signal communication with the storage cells. Furthermore, each cell module controller can be designed to detect cell statuses of the memory cells that have a signal connection and to output a module status based on the detected cell statuses. Furthermore, each energy storage controller can be designed to determine a storage state on the basis of the at least one module state. Alternatively or additionally, the traction energy storage system may include a system controller in signal communication with the energy storage controls.

According to another aspect, the disclosure includes a vehicle, preferably a motor vehicle, including an electric drive system as described in this document.

The vehicle can be a motor vehicle, e.g. B. be a passenger vehicle. The motor vehicle is preferably a commercial vehicle. In this case, the motor vehicle can, in other words, be a motor vehicle which, due to its design and equipment, is designed for transporting people, for transporting goods or for towing trailer vehicles. For example, the motor vehicle can be a truck, a bus and/or an articulated lorry that is at least partially electrically driven. The vehicle can also be an aircraft (plane), a rail vehicle or a watercraft, e.g. B. a ship.

Further details and advantages of the invention are described below with reference to the accompanying drawings. Show it: FIG. 1 shows an electric drive system with a central pre-charging circuit according to an embodiment of the invention;

FIG. 2 shows an electrical drive system with a DC/DC converter for providing the pre-charging functionality according to a further embodiment of the invention;

FIG. 3 shows an electric drive system with pre-charging circuits integrated into the individual energy stores according to a further embodiment of the invention; and

FIG. 4 shows a commercial vehicle with an electric drive system according to one embodiment.

Identical or equivalent elements are denoted by the same reference symbols in all figures and some of them are not described separately.

Figure 1 illustrates a first embodiment of the invention. An electric drive system 100 for an at least partially electrically powered vehicle, such as a commercial vehicle, includes a direct current network (high-voltage direct current circuit, HV-DC circuit) 2, the electrical energy of a traction energy storage system 10 z. B. to the electric drive motor 8 of the vehicle. The drive motor is in an alternating voltage circuit (AC circuit) 3 is arranged. The direct-current network is referred to here as a high-voltage direct-current voltage circuit (HV-DC circuit) 2 since the voltage provided by the traction energy storage system 10 is a high-voltage voltage and can amount to several hundred volts.

The electric drive motor 8 is not usually supplied with the direct voltage of the direct current network 2, but with alternating current. Therefore, an AC/DC converter (inverter) 4 is provided, which couples the HV-DC circuit 2 and the AC circuit 3 . The AC/DC inverter 4 has the task of converting the direct current of the direct current network into the respective current profile and vice versa, for example to recuperate kinetic energy of the motor vehicle. This means that there are coupled DC and AC networks.

The inverter can be designed to energize the windings of the drive motor 8 as required and thereby set a speed and a torque in the drive motor, and thus a desired or required operating point. The AC/DC inverter 4 comprises a power unit having a circuit arrangement having power semiconductor elements.

The traction energy storage system 10 forms a multi-battery architecture, i. That is, it is formed by a plurality of energy stores (e.g. batteries), which are connected in parallel and/or in series to the HV-DC circuit 2 . In the example of FIG. 1, an embodiment variant is shown in which the energy stores 11a, 11b, . . . , 11n are connected in parallel. For this purpose, the plus lines 17a, 17b, ..., 17n of the individual energy stores 11a, 11b, ..., 11n are placed on a common plus line 17 of the traction energy storage system 10 . The same applies to the negative lines 18a, 18b, ..., 18n of the individual energy stores 11a, 11b, ..., 11n, which are connected to a common negative line 18.

Each of the energy stores 11a, 11b, ..., 11n comprises a plurality of energy storage cells 12, an energy storage control 13 and main contactors 15, 16. The main contactors 15, 16 can be controlled by the energy storage control 13 in order to optionally connect the respective energy storage to the HV-DC switch circuit 2 on or off.

The traction energy storage system 10 also includes a system control or central control device 5 which is signal-connected to the energy storage controls 13 and is designed to issue a control instruction to the energy storage controls 13 in order to control the operation of the individual energy storage devices 11a, 11b, ..., 11n coordinate. The central control device 5 can act as a master controller that controls the energy storage controls 13 as slaves. The signal connection between the central control device 5 and the energy storage controls 13 is illustrated by the dot-dash line 6 . Each of the energy storage devices 11a, 11b, ..., 11n can have its own energy storage device housing 14, in which the storage cells 12, the energy storage control device 13 and the main contactors 15, 16 are housed.

A special feature of the traction energy storage system 10 is that the electrical energy stores 11a, 11b, . . . , 11n each have no integrated pre-charging circuit.

Instead, the pre-charging functionality is provided centrally by a central pre-charging circuit 20 . The central pre-charging device 20 comprises a main contactor 21 in a first line section and a pre-charging contactor 22 and a pre-charging resistor 23 which are arranged in a second line section which is parallel to the first line section. With means of the main contactor 21 and the pre-charging contactor 22 is a load output 17 (positive line) of the traction energy storage system 10 can be connected to the HV-DC circuit 2 and can be switched off from there. In the present case, the central pre-charging device 20 is designed as a central pre-charging box 24 which has its own housing.

The main contactor 21 and the pre-charging contactor 22 can be controlled by the control device 5 in order to change their switching position, and for this purpose they have a signal connection to the control device 5 (not shown). In normal operation, the pre-charging contactor 22 is open and the main contactor 21 is closed, so that the current flows via the upper line section. For pre-charging, however, the main contactor 21 is opened and the pre-charging contactor 22 is closed in order to bridge the upper line section. The current thus flows via the lower line section and is limited by the pre-charging resistor 23 .

Accordingly, a pre-charging functionality for the entire traction energy storage system 10 can be provided with less installation space and lower costs, e.g. B. to charge an intermediate circuit capacitance 7 when switching on the traction energy storage system 10 and generally to avoid short-circuit-type switch-on currents.

It is emphasized that the electric drive system 100 can include other components, for example various other electrical loads, e.g. B. Ancillaries and / or other inverters. Furthermore, the HV-DC network can be or can be coupled to a low-voltage DC network via a DC/DC converter.

FIG. 2 shows an electrical drive system with a DC/DC converter for providing the pre-charging functionality according to a further embodiment of the invention.

The electric drive system 200 again includes the traction energy storage system 10, the inverter 4, the intermediate circuit capacitor 7 and the drive motor 8, as has already been described in FIG. The electric propulsion system 200 further comprises a bidirectional DC/DC converter 40, a low-voltage direct current (LV-DC) circuit 50 and a battery 51 arranged in the LV-DC circuit 50, e.g. a lead-acid battery, and a load 52. The LV-DC circuit 50 is operated at a nominal voltage, e.g. B. 12 or 24 volts, which is less than the nominal voltage of the HV-DC circuit 2.

Here, too, the electrical energy stores 11a, 11b, . . . , 11n each have no integrated precharging circuit. In the embodiment of Figure 2, the Vorladefunktio nality for limiting inrush currents when switching on the traction energy storage Systems 10 in turn provided centrally instead. The special feature of this embodiment 200 is that a DC/DC converter provides this functionality. In other words, the central pre-charging functionality is formed by the DC/DC converter 40 . The DC / DC converter 40 is when switching on the traction energy storage system 10 controls such. B. from the control device 5 that the DC / DC converter 40 in this phase for pre-charging the HV-DC circuit 2 energy from the battery 51 in the LV-DC circuit 50 in the HV-DC circuit 2 transmits. In this pre-charging phase, the traction energy storage system 10 z. B. separated from the HV-DC circuit 2 via the separator 19 .

Accordingly, a pre-charging functionality for the entire traction energy storage system 10 can be provided with less installation space and lower costs, e.g. B., before switching on the traction energy storage system 10, first by means of the DC/DC converter via the battery 61, the intermediate circuit capacity 8 and other capacities in the HV-DC circuit 2 before charging.

It is emphasized that the electric drive system 200 can include other components, for example various other electrical consumers, e.g. B. Ancillaries and / or other inverters.

FIG. 3 shows an electric drive system 300 with pre-charging circuits integrated into the individual energy stores according to a further embodiment of the invention.

The electrical drive system 300 again includes a traction energy storage system 10' for providing electrical power for the HV-DC circuit 2 and the inverter 4, the intermediate circuit capacitor 7 and the drive motor 8, as has already been described in FIG.

The traction energy storage system 10' in turn comprises a plurality of electrical energy storage devices 11a', 11b', 11n', with each energy storage device comprising a plurality of cells 12 and an energy storage controller 13.

The special feature of this embodiment is that each of the several electrical energy stores 11a', 11b', 11n' has a pre-charging circuit 30 for limiting inrush currents when the energy store is switched on, with the pre-charging circuit 30 having a pulse width modulated circuit connected in parallel with the main contactor 15 of the respective energy store Semiconductor assembly 31 includes. The pre-charging circuit integrated in each of the energy stores does not therefore include a line branch arranged in parallel with the main contactor, in which a pre-charging contactor and a pre-charging resistor are arranged in series, but rather the pre-charging contactor and the pre-charging resistor are replaced by a semiconductor assembly 31, which is used for pre-charging in PWM operation is operated. The semiconductor assembly 31 can be power semiconductors, MOSFETs or the like. include, which can be controlled in PWM operation to set different currents. The semiconductor construction group 31 can, for example, be variably switched between low-impedance and high-impedance in order to set the current from the respective energy store during precharging, in particular to limit it. This results in a significant miniaturization of the pre-charging circuit. Accordingly, costs and weight can be saved. During pre-charging, the semiconductor assembly 31 is controlled accordingly to limit the current in PWM operation, for example by the control device 5.

It is emphasized that the electric drive system 300 can include other components, for example various other electrical loads, e.g. B. Ancillaries and / or other inverters.

Figure 4 illustrates schematically a commercial vehicle 1, which is equipped with an electric drive system 100, 200 or 300 as previously described.

Although the invention has been described with reference to specific embodiments, it will be apparent to those skilled in the art that various changes may be made and equivalents substituted without departing from the scope of the invention. Accordingly, the invention should not be limited to the disclosed embodiments, but should include all embodiments falling within the scope of the appended claims. In particular, the invention also claims protection for the subject matter and the features of the subclaims independently of the claims referred to. Reference List

1 motor vehicle, e.g. B. commercial vehicle

2 high-voltage direct current circuit (HV-DC circuit)

3 AC voltage circuit (AC circuit)

4 AC/DC inverters

5 control device

6 signal line

7 intermediate circuit capacitor

8 Electric prime mover 10, 10' traction energy storage system

11a, 11b, ..., 11n Electrical energy store

11 a', 11 b', ..., 11 n' Electrical energy store

12 battery cells

13 energy storage control

14 energy storage housing

15 main contactor

16 main contactor

17 positive line

18 negative line

19 separator

20 Central preloading device

21 main contactor

22 precharge contactor

23 pre-charge resistor

24 preload box

30 precharge circuit

31 Pulse width modulated semiconductor assembly

40 DC/DC converters

50 low-voltage direct current (LV-DC) circuit

51 voltage source, e.g. B. Battery

100 Electric Propulsion System

200 Electric Propulsion System

300 Electric Propulsion System

Claims

patent claims

1. Electrical drive system (100; 200) for a vehicle, comprising a) a high-voltage direct current circuit, HV-DC circuit, (2); b) an alternating voltage circuit, AC circuit, (3); c) an AC/DC inverter (4) for coupling the HV-DC circuit (2) and the AC circuit (3); d) a traction energy storage system (10) for providing electrical power for the HV-DC circuit (2), comprising a plurality of electrical energy storage devices (11a, 11b, 11n), each energy storage device (11a, 11b, 11n) having a plurality of cells (12 ) and an energy storage controller (13), and e) a central pre-charging device (20; 40) for limiting connection currents when the traction energy storage system (10) is switched on.

2. Electrical drive system (100) according to claim 1, wherein the central pre-loading device (20) has a main contactor (21), a pre-loading contactor (22) and a pre-loading resistor (23), with the main contactor (21) and the pre-loading contactor ( 22) a load output (17) of the traction energy storage system can be connected to and disconnected from the HV-DC circuit (2).

3. Electrical drive system (100) according to claim 2, wherein the central Vorladeeinrich device (20) is designed as a central Vorlade-Box (24), which preferably has its own Nes housing.

4. Electrical drive system (200) according to claim 1, further comprising a bidirectional onal DC / DC converter (40); a low voltage direct current, LV-DC circuit (50); a voltage source arranged in the LV-DC circuit, preferably a battery (51), the central pre-charging circuit being formed by the DC/DC converter (40), the DC/DC converter (40) being formed and/or is controlled to transfer energy from the LV DC circuit (50) to the HV DC circuit (21) for precharging the HV DC circuit (2).

5. Electrical drive system (100; 200) according to one of the preceding claims, a) wherein the plurality of electrical energy stores (11a, 11b, 11n) of the traction onsenergiespeichersystems (10) each have no pre-charging circuit; and or b) wherein the traction energy storage system (10) has no pre-charging circuit that is assigned to only one of the plurality of electrical energy storage devices (11a, 11b, 11n).

6. Electrical drive system (300) for a vehicle, comprising a) a high-voltage direct current circuit, HV-DC circuit, (2); b) an alternating voltage circuit, AC circuit, (3); c) an AC/DC inverter (4) for coupling the HV-DC circuit (2) and the AC circuit (3); d) a traction energy storage system (10') for providing electrical power for the HV-DC circuit, comprising a plurality of electrical energy storage devices (11a', 11b', 11n'), each energy storage device having a plurality of cells (12) and an energy storage device control (13), and e) each of the multiple electrical energy stores (11a', 11b', 11n') having a precharging circuit (30) assigned to the energy store and/or integrated into the energy store to limit switch-on currents when the energy is switched on memory, wherein the pre-charging circuit (30) comprises a main contactor (15) of the energy storage device connected in parallel with a pulse width modulated semiconductor assembly (31).

7. The electrical drive system (100; 200; 300) according to any one of the preceding claims, wherein each of the multiple energy stores comprises a) one or more interconnected cell modules and an energy store controller that is signal-connected to the at least one cell module, and the at least one cell module comprises a plurality of interconnected ones memory cells and a cell module controller in signal communication with the memory cells; and/or b) an energy storage housing.

8. Motor vehicle (1) comprising an electric drive system (100; 200; 300) according to egg nem of the preceding claims.

9. Motor vehicle (1) according to claim 8, wherein the motor vehicle is a utility vehicle, preferably a truck or a bus.