JP2017506498A - How to drive an electrical system - Google Patents

Abstract

The present invention is a method for driving an electrical system (1) for a motor vehicle, the electrical system (1) comprising a low voltage sub-network (21) for at least one low voltage consumer (29). And a high voltage subnetwork (20) for at least one high voltage consumer (25) and a starter generator (30), the high voltage subnetwork (20) comprising a coupling unit (33) And the coupling unit (33) is configured to obtain energy from the high voltage network (20) and transfer it to the low voltage network (21), and the high voltage subnetwork (20) has a battery (40), the battery (40) is configured to generate a high voltage and output it to the high voltage sub-network (20); Having at least two battery units (41) with individual voltage taps (42) guided to the base (33), the coupling unit (33) connecting the battery units (41) to the low voltage sub-network (21 ) To be connected to the low voltage subnetwork (21) from the first battery unit (41) connected to the low voltage subnetwork (21). The change to the second battery unit (41) is performed according to the following steps: a) a line between the connected first battery unit (41) and the second battery unit (41) to be connected; Disconnecting, b) connecting the second battery unit (41) to be connected to the low voltage subnetwork (21), and c) the connected first battery. Connecting the knit (41) to the low voltage subnetwork (21); d) connecting the first battery unit (41) separated from the low voltage subnetwork (21) to the low voltage subnetwork (21); Connecting the line between the second battery unit (41) and the second battery unit (41). Furthermore, the present invention relates to a battery management system and a computer program configured to execute the method, and an electric system and a motor vehicle capable of executing the method. [Selection] Figure 6

Description

  The present invention relates to a method for driving an electrical system for a motor vehicle.

  Furthermore, the present invention relates to a battery management system and a computer program configured to execute the method, and an electric system and a motor vehicle capable of executing the method.

  A motor vehicle equipped with an internal combustion engine is provided with an electric system that is typically driven at 12 volts for power supply to an electric starter or starter for the internal combustion engine and other electrical devices of the motor vehicle. It has been. When starting the internal combustion engine, a voltage is supplied to the starter by the starter battery via the electric system. The starter starts the internal combustion engine, for example, when the switch is closed by a corresponding start signal. When the internal combustion engine is started, the internal combustion engine drives a generator, which generates a voltage of about 12 volts and provides it to various electric consumer devices in the vehicle via the electric system. At that time, the generator also performs recharging of the starter battery loaded during the starting process. If the battery is charged via the electrical system, the actual voltage may be above the nominal voltage, for example 14V or 14.4V. An electrical system with a voltage of 12V or 14V is referred to as a low voltage electrical system within the scope of this disclosure.

  Electric vehicles and hybrid vehicles are known to implement other electrical systems with a nominal voltage of 48V and are also referred to as high voltage electrical systems within the scope of the present invention.

The method according to the invention is an electrical system for a motor vehicle, the electrical system comprising a low voltage sub-network for at least one low voltage consumer device and a high voltage for at least one high voltage consumer device. A high voltage sub-network connected to the low voltage sub-network via a coupling unit, the coupling unit taking energy from the high voltage network into the low-voltage network. The high voltage sub-network configured to communicate has a battery, the battery is configured to generate and output a high voltage to the high voltage sub-network, and a separate voltage tap guided to the coupling unit At least two battery units with a combination unit, the battery unit comprising a low voltage subnetwork To a configured to selectively connect, to the power system. In the method, the change from the first battery unit connected to the low voltage sub-network to the second battery unit to be connected to the low voltage sub-network is according to the following steps:
a) cutting a line between the connected first battery unit and the second battery unit to be connected;
b) connecting the second battery unit to be connected to the low voltage sub-network;
c) separating the connected first battery unit from the low voltage sub-network;
d) connecting a line between the first battery unit separated from the low voltage sub-network and the second battery unit connected to the low voltage sub-network.

  In the present invention, the low voltage sub-network drives the electric consumer device designated with the first low voltage. For the high-power consumer device, the voltage is higher than the high voltage sub-network, that is, the first voltage. It has the advantage that an elevated sub-electric system is provided. The power supply to the low voltage subnetwork overlaps with the charging process and the discharging process in the high voltage subnetwork. The power supply to the low voltage sub-network via the high voltage sub-network is unidirectional, i.e. the coupling unit preferably provides energy transfer only in one direction.

  The method is advantageous in that the power supply to the low-voltage sub-network can be performed without interruption, i.e. power can be supplied to the low-voltage sub-network from at least one battery unit even during the switching process. Provide a switching concept. This makes it possible to avoid a voltage drop in the low voltage sub-network without providing an additional temporary storage device. During the switching process, the battery continues to be provided to the high voltage sub-network as a reservoir. In doing so, the voltage may fall below the nominal value for a short time, but energy flow in both directions is possible, i.e. the battery can be charged and discharged.

  The concepts “battery” and “battery unit” are used herein for storage batteries or power storage units, in line with normal language usage. A battery includes one or more battery units, which may represent battery cells, battery modules, module wires, or battery packs. At that time, the battery cells are preferably spatially grouped and connected to each other by circuit technology, for example, connected in series or in parallel to form a module. The plurality of modules may form a so-called battery direct converter (BDC), and the plurality of battery direct converters may form a battery direct inverter (BDC).

  Advantageous developments and improvements of the subject-matter indicated in the independent claims are possible by means of the measures described in the independent claims.

  Thus, it is advantageous if each selectively connectable battery unit is designed to provide a low voltage. Accordingly, alternative demands are made for battery units to provide a low voltage, for example, to support a start-stop system, thereby extending the life of the battery unit.

  According to a preferred embodiment, it has at least one switch with reverse blocking capability. Preferably, the switch with reverse blocking capability is suitable for connecting or disconnecting a selectively connectable battery unit to or from the low voltage subnetwork. This switch has the property that in the “on” state it allows current flow in only one direction and in the “off” state it can accept reverse voltages of both polarities.

  When connecting the second battery unit to be connected in step b), preferably at least one switch with reverse-blocking capability is activated, particularly preferably two switches with reverse-blocking capability are activated. . At the same time, the separation of the connected first battery units in step c) likewise activates at least one switch with reverse blocking capability, particularly preferably two switches with reverse blocking capability.

  According to a preferred embodiment, the coupling unit has at least one switch with forward blocking capability. Preferably, the switch having the forward blocking capability is suitable for connecting the selectively connectable battery units in series. Preferably, upon disconnection of the line between the connected first battery unit and the second battery unit to be connected in step a), at least one switch capable of forward blocking is activated. Is envisioned. Similarly, preferably in the case of a line connection between the first battery unit separated from the low voltage sub-network and the second battery unit connected to the low voltage sub-network, the forward blocking capability It is envisioned that at least one switch is activated.

  According to a preferred embodiment, the second battery unit to be connected to the connected first battery unit is the connection of the second battery unit to be connected to the low voltage sub-network in step b). Later and before the separation of the connected first battery unit from the low voltage subnetwork in step c), it is connected in parallel to the low voltage subnetwork. Thus, when the charge states of the two battery units are significantly different, power may be supplied to the low voltage sub-network from a battery unit having a higher charge state or providing a higher voltage. It becomes possible. When the charge state of the battery units is the same or similar, the low voltage subnetwork is powered from both battery units.

  According to a preferred embodiment, the connected first battery unit and the second battery unit to be connected, or the separated first battery unit and the connected second battery unit, Is connected to a line between the connected first battery unit and the second battery unit to be connected, or between the separated first battery unit and the connected second battery unit. When connected, they are connected in series to the high voltage sub-network. Particularly preferably, the first battery unit and the second battery unit are connected to the high voltage sub-network when the line between the first battery unit and the second battery unit is connected. Are connected in series and next to each other. When it is necessary to change to a battery unit that is not directly adjacent, a plurality of switching steps are performed continuously in succession, and therefore, adjacent battery units are involved in each switching process.

  Additionally, it can be envisaged that the low voltage sub-network has at least one capacitor. The capacitor is preferably configured to continue to stabilize the low voltage when the connected battery unit is changed. The size of the capacitor is preferably determined according to the following formula.

Where I _max is the maximum electrical system current that can flow through the low voltage sub-network during the switching process, t _umschalt is the time during which the battery unit is not provided for power supply, and ΔU _max is the switching process It is the maximum allowable change amount of the electric system voltage between. Furthermore, the capacitor is also suitable as an energy store that is preferably configured to generate a low voltage for at least a short period of time and output it to a low voltage sub-network.

  If the switching takes place when the electrical system current is as small as possible, the voltage drop in the low-voltage subnetwork is advantageously further reduced. This can be done, for example, by evaluating the signal for the electrical system current and driving the switches of the coupling unit depending on the evaluation. In addition, the synchronization with the consumer equipment management system is also a process of switching battery units without causing a significant voltage drop to stop high power consumer equipment such as heating systems for a short time without losing comfort. Can be done to enable

  In accordance with the present invention, a computer program is proposed in which, when the computer program is executed on a programmable computer device, one of the methods described herein is executed accordingly. The computer program can be, for example, a module for realizing an apparatus for driving an electric system or a module for realizing a battery management system for a vehicle. The computer program may be stored in a machine-readable storage medium such as a permanent storage medium or a rewritable storage medium, or may be stored in an accessory of a computer device, for example, a CD-ROM. , A DVD, a Blu-ray (registered trademark) disk, a USB stick, or a memory card. Additionally or alternatively, the computer program may be downloaded on a computer device such as a server or cloud server for download via a data network such as the Internet or via a communication connection such as a telephone line or a wireless connection. May be provided.

  According to the present invention, there is further provided a battery management system (BMS) having an apparatus for performing the above method for driving an electrical system. In particular, the battery management system has a unit configured to control the coupling unit such that the battery unit is connected to and disconnected from the low voltage sub-network.

  According to the present invention, there is further provided an electrical system capable of executing the above method, wherein the coupling unit couples the battery units in series with each other for the high voltage sub-network and the battery for the low-voltage sub-network The electrical system is shown configured to couple units in parallel with each other.

  The electrical system can be used in stationary applications such as wind power plants, for example in vehicles such as hybrid vehicles and electric vehicles. In particular, the electrical system can be used in vehicles having a start / stop system.

  The systems introduced, namely the electrical system and the battery management system, are particularly suitable for use in vehicles having a 48V generator and a 14V starter, in which case the 14V starter is preferably started / Designed for stop system.

  The system introduced is particularly suitable for use in vehicles having a so-called boost regeneration system (BRS). In the boost regeneration system (BRS), electric energy is acquired during braking, traveling on a mountain road, or during coasting (SEGELBRIEB), and this electric energy is supplied to an electric consumer. BRS increases the efficiency of the system, thus saving fuel or reducing emissions. In doing so, the batteries in the high-voltage sub-network can support the internal combustion engine, which is called so-called boost, or the batteries are purely short-term and low-speed. It can be used to run on electricity, for example when parking electrically or leaving a parking lot.

  In accordance with the invention, there is further shown a motor vehicle with an internal combustion engine and a previously described electrical system.

  The present invention provides an inexpensive electrical system for a lithium-ion battery system for a vehicle, such as a high voltage sub-network comprising a 48V generator, a low voltage sub-network, and a low voltage sub-network. And a boost regeneration system that supplies electric power in one direction. In that case, it is possible to eliminate an insulation type DC / DC converter and a lead storage battery with respect to a well-known system. Further, no separate starter is required in the low voltage subnetwork. The boost regeneration system, in a suitable design, stores apparently more energy than the currently developed boost regeneration system, thereby allowing more electrical energy to be stored in the system during longer braking or mountain roads. It is possible to collect in the inside.

Embodiments of the invention are shown in the drawings and are explained in detail in the description of the following specification.
1 shows a low voltage sub-network according to the prior art. 1 shows an electrical system with a high voltage sub-network, a low voltage sub-network, and a unidirectional isolated DC / DC converter. 1 shows an electrical system with a high voltage sub-network, a low voltage sub-network, and a bidirectional isolated DC / DC converter. 1 shows an electrical system with a high voltage subnetwork, a low voltage subnetwork, and a unidirectional non-insulated DC / DC converter. Indicates a coupling unit. Fig. 6 shows the coupling unit of Fig. 5 in an exemplary driving state. 2 shows a switch with reverse blocking capability and a switch with forward blocking capability.

  FIG. 1 shows an electrical system 1 according to the prior art. When starting the internal combustion engine, a voltage is provided to the starter 11 by the starter battery 10 via the electric system 1. The starter 11 starts an internal combustion engine (not shown) when the switch 12 is closed by a corresponding start signal, for example. When the internal combustion engine is started, the internal combustion engine drives a generator 13, which generates a voltage of about 12 volts, and various electric consumer devices 14 in the vehicle via the electric system 1. To provide. At that time, the generator 13 further recharges the starter battery 10 that is loaded during the starting process.

  FIG. 2 shows an electrical system 1 that includes a high voltage subnetwork 20, a low voltage subnetwork 21, and a unidirectional insulated DC / DC converter 22. The unidirectional insulated DC / DC A DC converter 22 forms a coupling unit between the high voltage subnetwork 20 and the low voltage subnetwork 21. The electrical system 1 may be an electrical system of a vehicle, in particular a vehicle with a motor, a transport vehicle or a forklift.

  The high voltage subnetwork 20 is, for example, a 48V electric system including a generator 23 that can be driven by an internal combustion engine (not shown). In this embodiment, the generator 23 is configured to generate electrical energy according to the rotational motion of the motor of the vehicle and supply it to the high voltage subnetwork 20. The high voltage sub-network 20 further comprises a battery 24 that can be configured, for example, as a lithium ion battery, which is configured to output the required drive voltage to the high voltage sub-network. In the high voltage sub-network 20 there is arranged a further load resistor 25, which is preferably a plurality of load resistors 25, for example by at least one electric consumer of the motor vehicle driven at high voltage. It can be formed by electricity consuming equipment.

  The low voltage sub-network 21 arranged on the output side of the DC / DC converter 22 includes a starter 26 configured to close the switch 27 to start the internal combustion engine, and a low-voltage sub-network 21 for example An energy reservoir 28 is arranged that is configured to provide a nominal voltage of 12V. In the low voltage sub-network 21, another consumer device 29 that is driven at a low voltage is arranged. The energy store 28 includes, for example, a galvanic battery, and in particular, a galvanic battery with a lead-acid battery that normally has a voltage of 12.8 volts in a fully charged state (SOC (state of charge) = 100%). When the battery is discharged (SOC (state of charge) = 0%), the energy store 28 typically has a terminal voltage of 10.8 volts when unloaded. The electric system voltage in the low voltage sub-network 21 is in the range of approximately 10.8 to 15 volts according to the temperature and the state of charge of the energy storage 28 when driving.

  The DC / DC converter 22 is connected to the high voltage subnetwork 20 and the generator 23 on the input side. The DC / DC converter 22 is connected to the low voltage subnetwork 21 on the output side. The DC / DC converter 22 receives a DC voltage received on the input side, for example, a DC voltage of, for example, 12 to 48 V driven by the high voltage sub-network, and an output different from the voltage received on the input side. It is configured to generate a voltage, in particular an output voltage of eg 12V or 14V which is smaller than the voltage received at the input side.

  FIG. 3 shows an electrical system 1 including a high voltage subnetwork 20 and a low voltage subnetwork 21, and the high voltage subnetwork 20 and the low voltage subnetwork 21 are bidirectional bidirectional DC / DC converters 31. Connected by. The electrical system 1 shown is substantially configured as the electrical system shown in FIG. 2, but here the generator is incorporated in the high voltage subnetwork and between the subnetworks 20, 21. The DC / DC converter 31 configured in an insulated manner is used for energy transfer in the above. Furthermore, batteries 24, 28 and consumer devices 25, 29 are arranged in both sub-networks 20, 21 as described for FIG. In essence, the system shown in FIG. 3 differs in that a starter is incorporated. In the system shown in FIG. 2, the starter 26 is arranged in the low voltage subnetwork 21 so that the DC / DC converter 22 is unidirectional for energy transfer from the high voltage subnetwork 20 to the low voltage subnetwork 21. In contrast to the design shown in FIG. 3, the starter generator 30 is used in the high voltage subnetwork 20. In this case, the DC / DC converter 31 is realized in a bidirectional type, and thus the lithium ion battery 24 can be charged via the low voltage sub-network 21 in some cases. In that case, starting assistance of the low-voltage vehicle is performed via the low-voltage interface and the DC / DC converter 31.

  FIG. 4 shows an electrical system 1 with a high-voltage sub-network 20 and a low-voltage sub-network 21, for example a vehicle, in particular a motor vehicle, a transport vehicle or a forklift electrical system 1. The electric system 1 is particularly suitable for use in a vehicle including a 48V generator, a 14V starter, and a boost regeneration system.

  The high voltage sub-network 20 includes a starter generator 30 that can start an internal combustion engine (not shown) and can be driven by the internal combustion engine. The starter generator 30 is configured to generate electrical energy according to the rotational motion of the prime mover of the vehicle and supply it to the high voltage subnetwork 20. Another load resistor 25 is arranged in the high-voltage sub-network 20, and this load resistor 25 is, for example, at least one electric consumer device of a motor vehicle driven by a high voltage, preferably a plurality of It can be formed by a consumer device.

  The high voltage sub-network 20 further includes a battery 40 that can be configured, for example, as a lithium ion battery, which is configured to output a drive voltage of 48V to the high voltage sub-network. The lithium ion battery 40 preferably has a minimum capacity of about 15 Ah so that it can store the required electrical energy when the nominal voltage is 48 volts.

  The battery 40 includes a plurality of battery units 41-1, 41-2,... 41-n. At this time, a plurality of battery cells are associated with the battery unit 41. The cells are usually connected in series with each other and partially connected in parallel with each other in order to achieve the required power and energy data with the battery 41.

  The voltage units 80-11, 80-12, 80-21, 80-22, ... 80-n1, 80-n2 are associated with the battery units 41-1, 41-2, ... 41-n. The voltage is transmitted to the coupling unit 33 via these individual voltage taps 80-11, 80-12, 80-21, 80-22, ... 80-n1, 80-n2. The coupling unit 33 has the task of connecting at least one of the battery units 41 of the battery 40 to the low voltage subnetwork 21 for driving or supporting the low voltage subnetwork.

  The coupling unit 33 couples the high voltage sub-network 20 with the low-voltage sub-network 21 and provides the required drive voltage of, for example, 12V or 14V to the low-voltage sub-network 21 on the output side. The configuration and functional form of the coupling unit 33 will be described in the context of FIGS.

  The low voltage sub-network 21 comprises a low voltage consumer device 29 designed for driving with a voltage of 14V, for example. According to one embodiment, the lithium ion battery 40 is envisioned to supply power to stationary current consuming devices, shown as consuming devices 25, 29, when the vehicle (Fahrzeug) is stopped. For example, it can be envisaged here that so-called airfield inspection requirements are met, in which case the aircraft can still be started after a 6-week downtime, and the battery is powered by, for example, a burglar alarm device. In order to supply, a quiescent current is provided to the low voltage consumer device 29 in the low voltage sub-network 21 during the stop time.

  Optionally, the low voltage sub-network 21 is provided with a large power storage 28 or temporary storage that can output very large power in a short period of time, that is, optimized for high output. The large power storage device 28 satisfies the object that the overvoltage at the time of switching the battery unit 41 is largely avoided. When a capacitor is used as the large power storage 28, the size is preferably as follows.

Where I _max is the maximum electrical system current that can flow through the electrical system during the switching process, t _umschalt is the time when the battery unit 41 is not provided for power supply, and ΔU _max is during the switching process. This is the maximum allowable change in the electrical system voltage.

  The battery management system includes a controller that collects and processes measured data about the temperature of the battery 40 or battery unit 41, the provided voltage, the discharged current, and the state of charge. Based on this, for example, it comprises a further separate unit configured to make a statement about the health status of the battery.

  FIG. 5 shows a coupling unit 33 realized as a bidirectional non-insulated DC voltage converter (DC / DC converter). The coupling unit 33 includes switches 44 and 45 having reverse blocking capability. The switches 44 and 45 having reverse blocking capability allow current to flow only in one direction in the “ON” state, and are referred to as “OFF”. The second state has a characteristic that it can accept reverse voltages of both polarities. This is a fundamental difference from a single semiconductor switch, such as an IGBT (Insulated Gate Bipolar Transistor) switch. This is because the IGBT switch cannot accept a reverse voltage in the reverse direction based on its intrinsic diode. Based on the dependence on the direction of current flow, FIG. 5 shows two different types of switches, namely RSS_I45 and RRS_r44, which switches RSS_I45 and RRS_r44 need not be different in their manufacture, Only different polarities are created. An example of a detailed configuration of switches 44, 45 having reverse blocking capability will be described in connection with FIG.

  In the coupling unit 33, each individual tap 80 of the battery unit 41 is guided to one of different switches RSS_I45 and RRS_r44 having reverse blocking capability. The switch RSS_I 45 having reverse blocking capability is connected to the positive electrode 52 on the output side of the coupling unit 33, and the RRS_r 44 having reverse blocking capability is connected to the cathode 51 on the output side of the coupling unit 33.

  The coupling unit 33 includes a switch VSS 90 having a forward blocking capability, and the switch VSS 90 having the forward blocking capability can be, for example, a standard semiconductor switch. An example of a detailed configuration of switch 90 having forward blocking capability is described in connection with FIG. In the coupling unit 33, the individual taps 80 of the battery unit 41 are divided like branches, and are guided to the switch VSS 90 having each forward blocking capability in parallel with the switch having the reverse blocking capability. The switch VSS 90 having the forward blocking capability connects the battery units 41 in series when the switch 90 is closed. At that time, the switch VSS90 having the forward blocking capability is arranged between the two battery units 41. Therefore, when there are n battery units 41n-1, the switch VSS90- having the forward blocking capability is provided. 1, VSS90-2,..., VSS90-n-1 are provided.

  The voltage level of the high voltage subnetwork 20 relative to the ground of the low voltage subnetwork 21 depends on which battery unit 41 is connected. However, in any driving state, one of the potentials does not have a value that exceeds the voltage limit, which is the sum of the high voltage and the low voltage, that is, in the 48V network and the 14V network. Does not have a value exceeding about 62 volts. However, a negative potential can occur with respect to the ground of the low voltage subnetwork.

  The driving of the starter generator 30 does not depend on the driving of the coupling unit 33 and the power supply to the low voltage subnetwork 21. In the connected battery unit 41 that supplies power to the low voltage sub-network 21, either by the low voltage sub-network current and possibly the charging current (generator drive) supplied to the entire battery 40 by the starter generator 30, or , Duplication occurs due to the discharge current (motor drive) obtained from the entire battery 40. These processes are considered independent of each other as long as the allowable limit value of the battery cell, eg, the maximum allowable discharge current of the cell, is not exceeded. At least one battery unit 41 is always connected to the coupling unit 33 via corresponding switches 44, 45, 90 in order to reliably power the low voltage sub-network 21. Based on the fact that the power supply to the low-voltage subnetwork 21 is performed in multiple layers, a system with a very high availability of electric energy in the low-voltage subnetwork 21 is obtained by the structure introduced above. Built.

  FIG. 6 shows the switches RSS_145-i, RSS_145-j, RSS_r44-i, RSS_r44-j with activated reverse blocking capability, for example from battery units 41-1 and 41-2, and the open forward blocking capability. The power supply to the low voltage sub-network 21 is shown via the switch VSS90-1 that exists between the battery units 44-1 and 44-2. From the positive electrode 52, the first current path 71 passes through the switch RSS_145-i having reverse blocking capability, the first battery unit 44-1, and the other switch RSS_r44-i having reverse blocking capability. To the negative electrode 51. Furthermore, from the positive electrode 52, another current path 72 passes through the second battery unit 41-2 via the switch RSS_145-j having reverse blocking capability and further another switch RSS_r44- having reverse blocking capability. It communicates with the negative electrode 51 through j. When the switch 90-1 is opened, the first battery unit 41-1 and the second battery unit 41-2 are connected in parallel to the low voltage subnetwork. The positive electrode of the first battery unit 41-1 is connected with high impedance.

  In order to supply power to the low voltage sub-network 21 without interruption, in the present invention, the following switching method is determined, i.e., in the first step a), the connected first battery unit, i.e. Here, a switch between the battery unit 41-1 as an example and the second battery unit to be connected, here as an example, the battery unit 41-2 is a switch having a forward blocking capability arranged on the line. Disconnected by VSS90-1. After step a), the battery 40 has a total voltage of 36 volts, and this total voltage is provided to the high voltage subnetwork 20 so that bidirectional flow of energy is possible in the high voltage subnetwork 20. . In this case, further further battery units 41-2, ... 41-n form a series circuit of n-1 battery units.

  After this, in the second step b), the second battery unit 41-2 to be connected is low, with a delay (the delay time substantially depends on the switches 44, 45, 90 used). Connected to the voltage subnetwork 21. FIG. 6 shows a state after step b), in which two battery units 41-2 and 41-1 are connected in parallel.

  Deviation between stopping and running is necessary. If this deviation does not exist, the voltage in the low voltage sub-network 21 rises to an unacceptably high value in all switching steps during the transition process, ie in the case shown in FIG. -1 and 41-2 will be summed, i.e. doubled. If the coupling unit 33 is switched with a delay time, this means that the power supply to the low voltage sub-network 21 is interrupted for a short time. In order to avoid unacceptable voltage drops, according to some embodiments, temporary savings using capacitor 28 may be performed, as described in connection with FIG.

  In the third step c), when the change of the battery unit 41 connected to the low-voltage subnetwork 21 is provided, the connected first battery unit 41-1 is separated from the low-voltage subnetwork 21. . In the fourth step d), the line between the first battery unit 41-1 separated from the low voltage subnetwork and the second battery unit 41-2 connected to the low voltage subnetwork is again Established. After the line is re-established, the exchange from the first battery unit to the second battery unit is completed, and at that time, the power supply to the low voltage sub-network 21 is not interrupted.

  According to another embodiment of the invention, it can be envisaged that in step a) all switches 90 with forward blocking capability are stopped. The starter generator 30 does not supply energy to the high voltage sub-network in the switching process, and does not operate with boost driving. A little later (the delay time depends on the characteristics of the switch used), the switches 44, 45 having the reverse blocking capability of the battery unit 41 to be connected are activated. Therefore, it is possible to switch between the battery units 41 that are not directly adjacent to each other.

  FIG. 7 shows a possible configuration of switches 44, 45 with reverse blocking capability and switch 90 with forward blocking capability. At that time, the conduction direction of the switch is indicated by I. The switch RSS_r 44 having reverse blocking capability includes, for example, an IGBT, a MOSFET (Metal Oxide Semiconductor Field-Effect Transistor), or a bipolar transistor 101, and a diode 103 connected in series thereto. ,including. In FIG. 8, a MOSFET is shown with an inherent diode 102 shown together. The diode 103 connected in series with the MOSFET 101 has a polarity opposite to the direction of the diode 102 inherent to the MOSFET 101. The switch RSS_r 44 having a reverse direction blocking capability passes a current in the conduction direction I and blocks a current in the reverse direction. The switch RSS_145 having reverse blocking capability corresponds to RSS_r44, but is configured with the opposite polarity only, and therefore the conduction direction and the block direction are exchanged. The switch 90 with forward blocking capability includes a MOSFET, IGBT, or bipolar transistor 101, with its own diode 102 also shown. The switches RSS_145, RSS_r44, and VSS90 are also distinguished by a delay that is hardly noticed during the switching process, i.e. allows a very short switching time. Through a suitable drive circuit, the time difference between the stop and activation of the switch can be set very precisely.

  The present invention is not limited to the embodiments contemplated herein and the aspects highlighted therein. Rather, within the scope indicated by the claims, multiple modifications are possible that fall within the scope of those skilled in the art.

The driving of the starter generator 30 does not depend on the driving of the coupling unit 33 and the power supply to the low voltage subnetwork 21. In the connected battery unit 41 that supplies power to the low-voltage sub-network 21, by the high- voltage sub-network current and possibly the charging current (generator drive) supplied to the entire battery 40 by the starting generator 30, or , Duplication occurs due to the discharge current (motor drive) obtained from the entire battery 40. These processes are considered independent of each other as long as the allowable limit value of the battery cell, eg, the maximum allowable discharge current of the cell, is not exceeded. At least one battery unit 41 is always connected to the coupling unit 33 via corresponding switches 44, 45, 90 in order to reliably power the low voltage sub-network 21. Based on the fact that the power supply to the low-voltage subnetwork 21 is performed in multiple layers, a system with a very high availability of electric energy in the low-voltage subnetwork 21 is obtained by the structure introduced above. Built.

FIG. 6 shows the switches RSS_145-i, RSS_145-j, RSS_r44-i, RSS_r44-j with activated reverse blocking capability, for example from battery units 41-1 and 41-2, and the open forward blocking capability. a switch VSS90-1 having, with the switch VSS90-1 existing between the battery unit 4 1 1,4 1 -2 through, shows the power supply to the low voltage subnetwork 21. From the positive electrode 52, the first current path 71, through the switch RSS_l45-i having a reverse blocking capability, through the first battery unit 4 1 -1, the other switches RSS_r44-i having a reverse blocking capability To the negative electrode 51. Furthermore, from the positive electrode 52, another current path 72 passes through the second battery unit 41-2 via the switch RSS_145-j having reverse blocking capability and further another switch RSS_r44- having reverse blocking capability. It communicates with the negative electrode 51 through j. When the switch 90-1 is opened, the first battery unit 41-1 and the second battery unit 41-2 are connected in parallel to the low voltage subnetwork. The positive electrode of the first battery unit 41-1 is connected with high impedance.

Deviation between stopping and running is necessary. If this deviation is present, the voltage at the low voltage subnetwork 21, in all of the switching process during the transition process, up to a higher value unacceptable, i.e., in the case shown in FIG. 6, the battery unit 41 -1 and 41-2 will be summed, i.e. doubled. If the coupling unit 33 is switched with a delay time, this means that the power supply to the low voltage sub-network 21 is interrupted for a short time. In order to avoid unacceptable voltage drops, according to some embodiments, temporary savings using capacitor 28 may be performed, as described in connection with FIG.

FIG. 7 shows a possible configuration of switches 44, 45 with reverse blocking capability and switch 90 with forward blocking capability. At that time, the conduction direction of the switch is indicated by I. The switch RSS_r 44 having reverse blocking capability includes, for example, an IGBT, a MOSFET (Metal Oxide Semiconductor Field-Effect Transistor), or a bipolar transistor 101, and a diode 103 connected in series thereto. ,including. In FIG. 7 , a MOSFET is shown with an inherent diode 102 shown together. The diode 103 connected in series with the MOSFET 101 has a polarity opposite to the direction of the diode 102 inherent to the MOSFET 101. The switch RSS_r 44 having a reverse direction blocking capability passes a current in the conduction direction I and blocks a current in the reverse direction. The switch RSS_145 having reverse blocking capability corresponds to RSS_r44, but is configured with the opposite polarity only, and therefore the conduction direction and the block direction are exchanged. The switch 90 with forward blocking capability includes a MOSFET, IGBT, or bipolar transistor 101, with its own diode 102 also shown. The switches RSS_145, RSS_r44, and VSS90 are also distinguished by a delay that is hardly noticed during the switching process, i.e. allows a very short switching time. Through a suitable drive circuit, the time difference between the stop and activation of the switch can be set very precisely.

Claims (11)

A method of driving an electrical system (1) for a motor vehicle,
The electrical system (1) comprises a low voltage subnetwork (21) for at least one low voltage consumer (29) and a high voltage subnetwork (20) for at least one high voltage consumer (25). And the starting generator (30), the high voltage subnetwork (20) is connected to the low voltage subnetwork (21) via a coupling unit (33), and the coupling unit (33) Is configured to obtain energy from the high voltage network (20) and transfer it to the low voltage network (21), the high voltage subnetwork (20) comprising a battery (40), the battery ( 40) is configured to generate and output a high voltage to the high voltage sub-network (20) and is guided to the coupling unit (33) Having at least two battery units (41) with separate voltage taps (42), the coupling unit (33) selectively connecting the battery units (41) to the low voltage sub-network (21) Wherein the method is configured to:
The change from the first battery unit (41) connected to the low-voltage subnetwork (21) to the second battery unit (41) to be connected to the low-voltage subnetwork (21) is as follows. According to
a) cutting a line between the connected first battery unit (41) and the second battery unit (41) to be connected;
b) connecting the second battery unit (41) to be connected to the low voltage sub-network (21);
c) separating the connected first battery unit (41) from the low voltage sub-network (21);
d) Between the first battery unit (41) separated from the low voltage subnetwork (21) and the second battery unit (41) connected to the low voltage subnetwork (21). Connecting the wires of
A method characterized in that it is performed according to:   The method according to claim 1, characterized in that the battery units (41) are each designed to provide a low voltage.   The coupling unit (33) includes switches (44, 45) having reverse blocking capability, and the second battery unit (41) to be connected in the step b) is reversely connected. 3. A method according to any one of claims 1-2, characterized in that at least one switch (44, 45) capable of blocking is activated.   The coupling unit (33) has a switch (44, 45) having a reverse blocking capability. When the separation of the connected first battery unit (41) in the step c), the coupling unit (33) is reversed. 4. The method according to claim 1, wherein at least one switch (44, 45) capable of blocking is activated.   The coupling unit (33) includes a switch (90) having a forward blocking capability, and the connected first battery unit (41) in the step a) and the second battery unit to be connected ( The at least one switch (90) capable of forward blocking is activated during the cutting of the line between 41 and 41). the method of.   The connected first battery unit (41) and the second battery unit (41) to be connected are the second to be connected to the low voltage subnetwork (21) in the step b). After the connection of the battery unit (41) and before the separation of the connected first battery unit (41) from the low voltage sub-network (21) in step c), 6. A method according to any one of the preceding claims, characterized in that it is connected in parallel to the low-voltage subnetwork (21).   The connected first battery unit (41) and the second battery unit (41) to be connected are the connected first battery unit (41) and the second battery to be connected. 7. The device according to claim 1, wherein when the line to the unit (41) is connected, the high voltage sub-network (20) is connected in series and adjacent to each other. The method according to claim 1.   Battery management system for carrying out the method according to any one of claims 1 to 7, comprising a unit for controlling the coupling unit (33) for connection of the battery unit (41).   A computer program configured to perform the method of any one of claims 1 to 7 when the computer program is executed on a programmable computer device.   Electrical system (1) capable of performing the method according to any one of claims 1 to 7, wherein the coupling unit (33) is connected to the high voltage sub-network (20) with a battery unit ( 41) connected in series with each other, the electrical system (1) configured to couple the battery units (41) in parallel to each other for the low voltage sub-network (21).   A vehicle with a prime mover comprising an internal combustion engine and the electrical system (1) according to claim 10.

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