DE102017213017A1 - Method for operating a vehicle electrical system with multiple on-board network branches and vehicle on-board network - Google Patents

Abstract

A method for operating a vehicle electrical system with several on-board network branches (ESYS1, ESYS2, ESYS3) is described. The method provides that an overload condition is detected in a first on-board network branch (ESYS1). It is further provided that at least one second vehicle electrical system branch (ESYS2, ESYS3) is connected to the first vehicle electrical system branch (ESYS1) when the overload state has been detected. The connection comprises: changing a switching state of at least one controllable connection device (K1, K2) from a first switching state to a second switching state, wherein the connecting device (K1, K2) is switched when changing the switching state before reaching the second switching state according to a transition drive signal ,

Description

Numerous components of a motor vehicle are supplied with electrical energy. For the correct functioning of these components, a stable electrical system is required, i. an electrical system that provides a stable voltage.

Some components, such as the starter or other high-current loads, require a high current and disturb the on-board electrical system in such a way that they temporarily break the vehicle electrical system voltage. Other components such as entertainment systems or drive- or safety-related electronics do not provide any function at least for a period of time when the vehicle electrical system voltage of one or more on-board network branches temporarily drops or collapses significantly. Therefore, in the vehicle electrical system Bordnetzzweige formed, which can be separated from each other, so as to limit the influence of interfering components, while connected Bordnetzzweigen all loads can be supplied stably from all electrical energy sources of the connected on-board network branches.

For example, from the document DE 10 2014 208 257 A1 a stabilization circuit for a vehicle electrical system is known in which switches are opened or closed in order to separate and open vehicle electrical system branches from each other. Switching may result in transients that represent a fault in the vehicle electrical system, which has a negative effect on the stability. It is therefore the task of pointing out a possibility with which the stability in on-board networks can be improved.

This object is achieved by the objects according to the independent claims. Other features, embodiments, advantages and features will become apparent from the description, the drawings and the dependent claims.

• - Erfassen eines Überlastungszustands in einem ersten Bordnetzzweig und
• - Zuschalten mindestens eines zweiten Bordnetzzweigs zum ersten Bordnetzzweig, wenn der Überlastungszustand erfasst wurde, wobei das Zuschalten umfasst: Ändern eines Schaltzustands bzw. Verbindungszustands mindestens einer steuerbaren Verbindungsvorrichtung von einem ersten Schaltzustand, insbesondere einem Anfangszustand, auf einen zweiten Schaltzustand, insbesondere einem Endzustand, wobei die Verbindungsvorrichtung beim Ändern des Schaltzustands vor dem Erreichen des zweiten Schaltzustands gemäß einem Übergangs-Ansteuersignal geschaltet wird.

In a method according to the invention, a vehicle electrical system with a plurality of on-board network branches is operated with the following steps:

• - Detecting a state of overload in a first electrical system branch and
• Connecting at least one second vehicle electrical system branch to the first vehicle electrical system branch when the overload condition has been detected, the connection comprising: changing a switching state or connection state of at least one controllable connection device from a first switching state, in particular an initial state, to a second switching state, in particular a final state, wherein the connection device is switched when changing the switching state before reaching the second switching state according to a transition drive signal.

In particular, the connecting device in the first switching state and / or in the second switching state is only completely open or only completely closed, i. essentially no current flows through the connection device and the on-board network branches are not coupled (completely open) or substantially maximum current flows through the switch and the on-board network branches are coupled with maximum low-impedance directly (completely closed).

It has been recognized that the transients that result in the switching processes between different on-board network branches can be significantly reduced by introducing a transition phase between the stable switching states instead of a "hard" circuit in which two (opposite) stable switching states immediately detach becomes. Therefore, instead of putting the connection device, which performs the connection, starting from a first switching state directly in a second, the target switching state is switched before reaching the second switching state according to a targeted transition, for example, extends over a minimum period of time or an upper limit for has the amount of the first time derivative of the voltage or the current.

The transition is realized by switching the connection device according to a transition drive signal before reaching the second switching state. This is set up to realize a targeted, slower transition from the first switching state to the second switching state. Between the first and the second switching state, in particular before the second switching state, the connecting device is driven in a transitional state. The transition drive signal is arranged to generate a transition (from the first) to the second switching state, wherein the amount of the first derivative of a connection degree (the connection device) over time, the amount of the first derivative of a current or the amount of the first derivative of a Power by the connection device or the amount of the first derivative of a voltage of one of the electrical system branches remains below a predetermined level or is otherwise defined.

The transition drive signal is in particular configured to limit the current and / or the power according to an upper limit. The transition drive signal may be further configured to limit the voltage dip, i. to limit the voltage according to a lower limit.

As a connecting device, a linear actuator such as a linear transistor, a switching transistor, a switch (in particular with upstream or downstream inductance) or a power converter, such as a DCDC converter (DC-DC converter) can be controlled.

Before reaching the second switching state, a linear actuator can be controlled as a connecting device in an at least partially linear operating state, in which the connecting device is neither completely closed nor fully opened, but has a state between these states. In the transient state, a voltage greater than the pass voltage drops across the connection device and the current is greater than zero. For a transistor switch, this corresponds to linear operation.

In the case of a switching transistor as a connection device, it can be driven in accordance with a pulse sequence. The pulse sequence comprises more than one switching edge and in particular goes beyond the direct change from the first to the second stationary switching state.

In a power converter, which is regulated in particular, as a transition control signal, for example, a nominal value is changed at least partially continuously or stepwise (until the second switching state is reached). In combination or alternatively, at least one input parameter of the controller (in particular an input parameter which defines the transfer function of the controller or its behavior) may have a different value during the transition state than during the first and / or second stationary switching state. The value of the at least one input parameter during the transition state is associated with a lower dynamic than compared to the value of the at least one parameter during the first and / or the second switching state. If the converter is equipped, for example, with a P-controller, a PI controller or a PD controller or a PID controller, then the input parameter is P during the transient state smaller than during the first and / or second switching state. The transient drive signal may include such an input parameter such that the transient drive signal sets the behavior of the (regulated) power converter differently during the transient state on the one hand and during the first and / or second switching state, on the other hand.

The transition drive signal extends over a minimum period of time. This also applies to the transition state. This results in a "smooth" transition between the first and the second switching state.

In particular, the connection device provides a monolithic solution for connecting two on-board network branches with the transition phase.

In the following paragraph, embodiments are considered in which the transition drive signal is defined by a pulse train and thus the transition state is controlled by this pulse train.

When connecting or even when disconnecting a second electrical system branch can be switched by means of a switching device (such as by means of a switch, in particular a switching transistor) before reaching the second switching state according to the pulse sequence. In particular, when switching on or disconnecting a second electrical system branch by means of a switching device (such as by means of a switch) between the first switching state and the second switching state according to the pulse sequence is switched. As mentioned, the pulse sequence preferably goes beyond a single switching edge but comprises a plurality of switching edges or states.

The transition drive signal may define at least one at least partially continuous transition which, in particular by means of a linear control or a pulse width modulation, realizes a continuous or at least gradual transition between the first switching state and the second switching state.

The transition drive signal is arranged to generate a continuous or at least step-wise transition (from the first) to the second switching state. This transition is called a "transition state". In other words, when the switching state is changed, the connecting device is continuously (or stepwise) transferred from the first switching state to the second switching state, in particular, providing the transition drive signal for continuity or preventing the connecting device from the first switching state directly to the second switching state passes.

In the case of a power converter, such as a DC / DC converter, which controls or regulates the two electrical system branches is switched when changing the switching state before reaching the second stable switching state according to a transition drive signal, which is a continuous transition from a first target voltage to a second target voltage (as a target size for the power converter) reproduces. The transition control signal can define the course of a desired value of the control of the power converter or can define at least one control parameter of the (regulated) power converter.

In a transition control signal defining a switching state, such as a switching transistor as a connection device, the transition control signal may be provided as a pulse sequence. The pulse sequence comprises at least one or even a plurality of switching edges which represent a transition and, in particular, do not (as a single switching edge) represent a direct transition between the first switching state and the second switching state. Particularly in the case of a power converter, the pulse sequence comprises a plurality of pulses or (intermediate) states and thus differs from an immediate changeover to a new setpoint voltage of a power converter, in which only a single switching edge or a single fast state change represents the transition. The pulse sequence comprises a plurality of pulses and in particular comprises a plurality of switching edges. The sequence is therefore called the sequence of several pulses. The pulse sequence extends over a minimum period of time, which may be, for example, at least 10 ms or else 20 ms or, in the case of particularly smooth transitions, more than 100 ms, 500 ms or more than 1 s.

A method is therefore described for operating an on-board network having a plurality of on-board network branches, comprising the following step: Detecting an overload state in a first vehicle electrical system branch. Here, the overload state can be detected, for example, by exceeding a predetermined current limit or power limit (in the electrical system branch) or temperature limit or by falling below a voltage in the first electrical system branch. The detection can thus be implemented by determining a current or a voltage and by comparing this determined current or the determined voltage with one of said limits. The overload condition can also be detected by a control signal of a load, the load being particularly responsible for the fault or for the overload condition. In particular, a start signal of an internal combustion engine can be detected in order thus to conclude the load state, since the starting process is associated with the activation of a starter and thus with the overload of the first on-board supply system branch (ie with an undershooting of a voltage limit).

At least one second vehicle electrical system branch is connected to the first vehicle electrical system branch when the overload condition has been detected. The connection can be provided by a direct connection is made via at least one switch, by connecting a second Bordnetzzweig other than previously connected to the first electrical system branch, or by a current regulator of the second Bordnetzzweig (other than before ) is connected to the first electrical system branch. The switch may be upstream or downstream of an inductance. The connection device may comprise the switch and possibly a series inductance, which is connected in particular in series with the switch.

The different on-board network branches comprise different (non-identical) loads and / or different (non-identical) energy stores. As loads, electric motors, control units, electric compressors for air conditioners, electric catalyst heaters and others are considered. Energy sources such as batteries or capacitors or Kondensatorenbänke come into consideration as energy source in the various electrical systems branches, or even generators that convert chemical or mechanical energy into electrical energy, such as electromagnetic generators or fuel cells or the like.

The switching state is preferably set by a control or control element, in particular according to a transition which is at least partially continuous or stepwise. This avoids uncontrolled transients resulting from discrete connection, that is to say by an immediate transition between two switching states. Switching states in the case of switches are, in particular, the states On and Off, while in the case of power converters the switching states are defined, for example, by different setpoint voltages, such as setpoint output voltages. As a stable switching state, therefore, the off and the on state can be considered in the switch, while in converters as a stable switching state, the specification of a desired voltage or a desired current (in each case at least temporarily constant) is considered. In the case of the switch, the control mode by linear operation can also be referred to as a desired stable state in this case as well.

It is the switching state of at least one switch or a power converter changed. The switch (possibly connected in series with series inductance) or the power converter form the connecting device. The at least one switch can also be provided as a switch, which is designed in the form of two mutually connected switches. The switching state is changed when switching by a control input (of the switch) receives another potential, while in the case of a power converter as a connecting device this another setpoint (as a first setpoint) is specified (or the setpoint is changed), for example, the Current representing the voltage, the duty cycle, the frequency or the pulse width, according to which the converter is controlled becomes. The control of switches and converters is independent of each other, but may also be state coupled, especially when the on-board network topology so requires. The switching state can be changed during switching by changing the potential or the signal of a control input (of the switch). The change can take place between two signal levels or potentials or can take place in stages or can be continuous. There may be two, more than two or (in continuous, especially linear transitions) infinitely different potentials in the transition state. These signals or potential can reproduce the transition drive signal.

1. (1) Stand-by (ausgeschaltet)
2. (2) angeschaltet („AN“) mit Boost-Betrieb, vorzugsweise bi-direktional
3. (3) angeschaltet („AN“) mit Buck-Betrieb, vorzugsweise bi-direktional
4. (4) Fast response (Schnelle Antwort) und
5. (5) Slow response (Langsame Antwort)

Thus, a pulse sequence as a transition drive signal according to which the relevant connection device is switched, have a pulse width or a duty cycle or a frequency which is a manipulated variable, in particular a controller or a control. This relates to a control or activation of the connecting device, which is discrete and in particular binary. Instead, an amplitude-continuous (possibly discretized according to a resolution) signal can be used as a transition control signal, in particular in a linear control. In this case, the manipulated variable is, for example, a voltage or another signal or a numerical value. In particular, the manipulated variable is changed continuously or via at least one intermediate value (ie stepwise) before reaching the second stable switching state. This results in at least one state for the pulse sequence that neither the first stable switching state ( ON ) nor the second switching state ( OFF ), but more particularly represents an intermediate state (between the two switching states). There may be a controlled control by switch or DCDC converter. If the controller is not used for the switches, but they have one of the two stable switching states ( ON or OFF ), the controller can be used for the DCDC converter. Is the DCDC converter in the state " OFF ", The controller can be used for the first and / or second switching state. The DCDC converter or the connection device can have one, several or all of the following five operating states:

1. (1) stand-by (off)
2. (2) switched on ("ON") with boost operation, preferably bi-directional
3. (3) turned on ("ON") with buck operation, preferably bi-directional
4. (4) fast response and fast response
5. (5) Slow response

In one of the operating states, namely ( 4 ), the connection device has a more dynamic control than in another of the operating states, namely ( 5 ). In the one operating condition, namely ( 4 ), a P input parameter is used for the control, which is greater than in the other operating state, namely ( 5 ). The transition state is preferably the state ( 5 ).

If at least one intermediate state is provided, then this can also be regarded as a continuous transition since there is no direct, direct transition between the two switching states.

The control or regulation preferably defines a chronological course of the change of the switching state. This time profile is preferably continuous or comprises at least one and preferably several intermediate states between the two switching states. The time course of the change is preferably determined by a predetermined dependence of the choice of the control parameters ( I1 . I2 . I3 . V1 . V2 . V3 and their mathematical relationship to each other), as well as the pulse width, the duty cycle or the frequency of the time given. Alternatively, this is given by at least one input parameter of the control or regulation. The input parameter defines, for example, the transfer function and / or the impulse response of the control (to a jump function or the like or to a Dirac impact). The input parameter is in particular a parameter of a linear control. If the time course of the change is defined by a predetermined dependence of the pulse width, the duty cycle, the frequency (or another, the pulse sequence defining) of the time, then this course can be defined by a value sequence, which is in particular predetermined or deposited, or that results from other values that are deposited. In this case, the course is predetermined, while in the case of a control or in particular a control only the reaction of the control or regulation is defined to changed setpoints, the time course itself but also from the setpoints and in particular in the control of the error within the control loop depends.

It can therefore be provided that at least one input parameter of the pulse sequence is a manipulated variable of a regulator, in particular of a linear regulator. The input parameters here can be the pulse width, the duty cycle or the frequency or also an instantaneous power of the pulse sequence. The controller controls the transition between the first and the second stable switching state. As the setpoint of the controller, the second switching state, a target voltage (in particular in the first and / or in the second electrical system), a Target current, a target power or the like serve. The setpoint refers to the connection device. The controller may be configured to output the pulse sequence in such a way that a predetermined maximum current through the connecting device is not exceeded.

The controller is in particular a linear controller. The linear controller may be a P controller, a PD controller, a PI controller, or preferably a PID controller. The controller may also have a higher order transfer function (as compared to a PID controller). The actual size may be a current connection state, a current transmitted by the connection device or a voltage in the first, the second or both on-board networks or control parameter combinations (eg Isoll = I1-I2, Psoll = I1 * V1), which are varied at any time can), cf. Description to 1 , Preferably, the transfer function of the controller essentially corresponds to an asymptotic limit case when approaching the second stable switching state. In addition, it can be provided that the controller is not exceeded a predetermined limit for the first time derivative of the switching state or of the current flowing through the connecting device current.

The connection of the second electrical system branch can be done by connecting it in parallel to the first vehicle electrical system branch when the nominally similar voltage states of both vehicle electrical system branches permit this. In this case, the second electrical system branch is connected by closing a switch to the first electrical system branch, according to the invention, the pulse sequence before reaching the second stable switching state, that is the on state (closed) of the relevant switch, the connecting device (in this case, the switch ) switches. The switch is in particular a semiconductor switch, preferably an IGBT or a MOSFET or relay or an antiserial MOSFET circuit (MOSFET - metal oxide semiconductor field effect transistor) which in the OFF state blocks the current in both directions, such as a relay (normal Open).

Furthermore, the connection of the second electrical system branch can provide that the second vehicle electrical system branch is connected in series with the first vehicle electrical system branch. It is possible that in the first stable switching state of the second electrical system branch is connected in parallel to the first electrical system branch, and is connected in series in the second switching state. In parallel and / or in the serial connection, the first electrical system branch can be connected via a DC / DC converter, in particular to compensate for different voltage levels (the first operating voltages). Changing the switching state of the at least one connecting device may further provide that a first switch of a changeover switch is opened and / or a second switch of the changeover switch is closed. In this case, the connection device is a changeover switch, which in particular switches a pole or a supply potential of the second vehicle electrical system branch from a connection to a first potential (possibly of the first vehicle electrical system branch) to a second potential (as well as the first vehicle electrical system branch, if applicable). Here, the first and the second switch each have a terminal which is permanently connected, in particular with a potential of the second electrical system, while the other terminals of the two switches with different potentials (in particular the first electrical system branch) are connected.

The controllable connection device can thus be designed as a switch, DC / DC converter and generally as a power controller. The connection device can furthermore be realized by a clocked switch, which in particular comprises a wiring harness or electrical line for the power line. The two electrical system branches are preferably connected to one another via the switch and the line. The switch connected in series with the switch is, in particular, just like the switch part of the connecting device.

The connecting device is an actuator of a control device that implements the control described above. The input parameters of the controller, ie the parameters that define the transfer function of the controller or its behavior can be specified partially or completely via an input, or can be stored in a memory, which is preferably readable and writable. As a result, the controller can be set according to the field of application or according to the application. In the case of a linear regulator, the input parameters may be stored in the memory in terms of control parameters, for example the proportional, the integral and / or the differential factor. In addition, setpoint specifications can be provided, thermal limits, or the like, in particular temporal courses of setpoint specifications. As a result, for example, at the beginning of the connection or at the beginning of a control sequence, the control can be set to a maximum total power, which represents in particular the end of the first switching state, in which case a target voltage value or a target current value, in particular when switching, ie to the transition to the second stable switching state with current limitation, are provided. In this case, for example, the pulse sequence implements the corresponding function as an actuator. The connection, and in particular the transition from the first to the second switching state can start at a minimum amplitude, maximum amplitude or another predetermined amplitude, the amplitude being exemplary refers to the power of the pulse sequence, which in turn reflects the current or power amplitude or the degree of connection of the connecting device.

Furthermore, the pulse sequence can be stored in the memory or else an input parameter defining the pulse sequence, for example a time profile of a parameter defining the pulse sequence, such as frequency, duty cycle, pulse width, power, current or voltage. For different states of the first and the second onboard electrical system, a plurality of pulse sequences can be stored, which are selected depending on a state of the electrical system branches, for example, the voltage difference or the expected current when connecting as a criterion (in the selection) is taken. For different criteria or different heights of these criteria different pulse sequences are retrieved from the memory to control the connection device according to these pulse sequences.

In such pre-stored pulse sequences are prefabricated control curves of the connecting device, wherein when using a controller to define the pulse sequence not the course itself is exactly predetermined, but the behavior of the controller on the influencing variables of the controller (voltage, voltage difference, current, power or the like, based on the first electrical system branch and / or second electrical system branch).

1. 1. Starten des Hybridfahrzeugs mit I1 * U1 = P in beispielsweise weniger als 100 ms als der Zeitparameter oder in vorzugsweise weniger als 50 ms als der Zeitparameter;
2. 2. Stromregeln d.h. I1 anpassen, insbesondere limitieren;
3. 3. Spannungsregeln d.h. U1 anpassen.

The input parameter is preferably designed as a control parameter, set up for comparison with an actual state value connection device, or as a configuration parameter configured for setting the connection device. The control parameter can be designed as a current value, voltage value or temperature value. Preferably, during the change of the switching state, the actual state value is detected and compared with the control parameter. Based on the comparison, the control or regulation of the connecting device can then be carried out. The configuration parameter can be a PID (Proportional, Integral, Derivative, or Initial) value, and the initial value can be a Low, Variable, High, or Control parameter combination, giving the possibility of timing of the controller or controller However, the configuration parameter can also be present as a time parameter. The time parameter can be provided for controlling a starting hybrid vehicle, for example in the following sequence:

1. 1. starting the hybrid vehicle with I1 * U1 = P in, for example, less than 100 ms as the time parameter, or preferably less than 50 ms as the time parameter;
2. 2. adjust current rules ie I1, in particular limit;
3. 3. Adjust voltage rules ie U1.

Furthermore, it is possible that the connection device is formed by a DC / DC converter, which is controlled according to the above described mechanisms. In addition to the DC / DC converter, a switch can be provided which changes from a first switching state directly into a second switching state, i. either turned on or off), the DC / DC converter being used to drive the switching state and the second on-board network branch as described herein according to a pulse sequence (pre-stored or generated according to regulation or control).

The method described here is suitable for vehicle electrical systems with two or three or even more than three electrical system branches, whereby a third vehicle electrical system branch such as the second vehicle electrical system branch can also be connected. Furthermore, the first on-board network branch (or else third or further on-board network branches) can be separated, in which case the same mechanism is preferably used, for example to avoid overvoltages or voltage dips in the form of voltage peaks in the event of a sudden switch-off or switching on or switching over. Rather, in particular during separation by means of the pulse sequence continuously, pseudo-continuously or step by step from a stable switching / control state in the next switching / control state, in particular from the first stable switching / control state in the second stable switching / control state and / or vice versa. As mentioned, the pulse sequence can be designed in such a way that the connection device switches on continuously, pseudocontinuously or stepwise in the second on-board network branch even when switching on. The result is a transition phase or a transitional state, the or a minimum duration persists, and ensures that in particular the time derivative of the voltage, power or current change in the first and / or second electrical system branch does not have a predetermined Limit value goes. This results in a predetermined, limited transient.

The electrical system branches or energy storage devices or generators within these on-board network branches can have different operating voltages. For example, the first electrical system branch may have a rated voltage of 12 volts, while the second electrical system branch a Rated voltage of 48 volts may have (that would be, for example, the switch K1 replaced by a DCDC converter). In the same way, the first electrical system branch may have a nominal voltage of 12 volts, while the second electrical system branch has a rated voltage of 360, 380 or 400 volts or higher. DC / DC converters are used to adapt the voltages to one another, for example a DC / DC converter in the second or in the first vehicle electrical system, which can also serve as a connecting device, which is switched according to pulse sequence. In particular, when using DC / DC converters as a connecting device, the pulse sequence is a curve of the converter current, the converter power or the (output) voltage again, which is either predetermined or determined by a controller or a controller whose behavior or transfer function is predefined by parameters.

Furthermore, an on-board vehicle network is described for carrying out the method described here. The vehicle electrical system, in particular an electric vehicle or a hybrid vehicle, comprises at least the first vehicle electrical system branch and the second vehicle electrical system branch. Furthermore, the vehicle electrical system comprises a controllable connecting device, in particular the connecting device, as has been described above. The connection device is set up to connect the second vehicle electrical system branch to the first vehicle electrical system branch. Thus, the connection device between the first electrical system branch and the second electrical system branch is provided and connects them electrically (and controllable). The connecting device is set up to switch on the second vehicle electrical system branch to the first vehicle electrical system branch by changing between a first switching state and a second switching state. These switching states correspond to the aforementioned switching states. Alternatively or in combination with this, the connection device is set up to separate the second vehicle electrical system branch from the first vehicle electrical system branch in this way.

The vehicle electrical system has a drive unit which is connected to the controllable connection device. Alternatively, the drive unit may also be part of the connection device, in particular if it is a DC / DC converter as a connection device. The drive unit is set up to switch the at least one connection device when changing the switching state before reaching the second stable switching state according to a pulse sequence. A memory can be provided, in particular as part of the drive unit, in which the pulse sequence itself is stored in the form of a sequence of values, or are stored in the input parameter, which define the pulse sequence itself as a sequence of values. Alternatively, at least one input parameter, which is a control or regulation parameter of a control or regulation realized by the drive unit, is stored in the memory. The latter, at least one input parameter defines the transfer function of the control or regulation realized by the drive device.

The memory is rewritable (or writable at least once). The memory in particular comprises an interface by means of which the data in the memory can be described and, in particular, can be changed. As a result, the pulse sequence (as a sequence of values or as an input parameter defining the value sequence) or as at least one control or regulating parameter can be stored in the memory via the interface. The memory is set up to be described when the memory or the drive unit is already installed in the vehicle electrical system. Instead of a memory, an input can also be provided, via which the data can be entered, which are described above as being storable in the memory. This allows an external memory to be connected to the input so as to receive via the input data defining the pulse sequence itself or to define the control parameters.

The connecting device is designed as at least one switch (possibly with upstream or downstream series inductance) or as a power converter. The connection device can furthermore be designed as a switch, which is brought directly from a first switching state into a second switching state, which is preceded or followed by a converter, but which is switched according to the pulse sequence described here and is set up, a continuous, pseudo-continuous or to perform gradual transition between the first switching state and the second switching state (or vice versa).

The power converter is designed in particular as a synchronous converter, up or down converter. The switch is preferably a semiconductor switch, such as an IGBT or a MOSFET.

The second vehicle electrical system branch can be connected in series or in parallel to the first vehicle electrical system branch; the connecting device accordingly forms a parallel or serial connection.

Furthermore, the drive unit may have a signal generator which is set up to output the transition drive signal. In particular, the signal generator can be a state sequencer which issues state sequences, in particular to the connection device designed as a DC / DC converter. If the connecting device is designed as a switch, such as a switching transistor, then the signal generator may be formed as a pulse generator. The pulse generator may output switching pulses of variable frequency, variable pulse width or variable duty cycle. If the connecting device is designed as a linear actuator, for example as a linear transistor, then the signal generator can be designed to output a value- or amplitude-continuous drive signal (for example a voltage). This can be supplied as a gate voltage or base voltage to the transistor.

In particular, the signal generator comprises an input via which at least one control parameter of the connection device can be set. The signal generator comprises the actuator of a control and regulation element or forms this actuator or controls a corresponding, downstream actuator. The actuator is configured to set a control parameter, a control target value, a pulse width, a duty cycle or a sequence as a manipulated variable of a control or a control, or is adapted to output a control signal for setting a linear operating point of a transistor. The control is provided by the control element. The control element realizes the aforementioned control.

Preferably, the control element is implemented by a processor or by a configurable monolithic unit (including a processor or ASIC). The control and regulation element comprises in particular a memory or an input, on which at least one input parameter can be stored or entered, which defines the transfer function of the regulation or control. In this embodiment, the pulse sequence is formed by the control unit (using the pulse generator as an actuator), with the control characteristics defined by the at least one input parameter. The input parameter is preferably stored in a rewritable memory and can thus be configured.

Another possibility is to define the transition drive signal (for example the pulse sequence) as such by means of a sequence of values. The drive unit may have a pulse generator which is connected to a memory of the drive unit. In the memory, the transition drive signal (in particular, as a plurality of values) is stored. Instead of storing the values of the transition control signal itself in the form of entries in the memory, values or input parameters may be stored in the memory which characterize the time profile of the transition control signal, in particular in the time course of at least one variable representing the transient Control signal indicates. Such a quantity would be, for example, a state (which changes according to the signal), a voltage, the duty cycle, the frequency (the pulse sequence) or the like.

Coming back to embodiments in which the signal generator is an actuator of a control or control (and thus not the drive signal itself is defined, but only the behavior of the control or regulation), the drive unit on a linear controller. The linear regulator adjusts a pulse width, a duty cycle, a frequency of the pulse sequence or a (linear) operating point of the transistor, these variables representing in particular the manipulated variables of the linear regulator.

The linear controller is preferably a PID controller. Its actuator is formed by the drive unit (in particular by the signal generator). The input parameters of the PID controller are stored in a memory. Alternatively, these can be entered at an input of the drive unit. Thus, the drive unit and in particular the control element can have an input at which the input parameters can be input. If the input parameters are stored in a memory, they are preferably stored overwritable; For this purpose, the memory can have an input by means of which the contents of the memory (in particular the input parameters) can be overwritten.

If the drive unit has a control unit or a control unit, in particular a controller, then this preferably has an input for an actual variable, such as a voltage, a voltage difference (between the on-board network branches), a power or a current flowing through the connecting element , Furthermore, the control or regulation can be set up to control or output the relevant actuator or the transition control signal such that a lower / upper limit is not undershot / exceeded, for example a power, current or voltage upper limit, possibly also a temperature upper limit or a voltage difference upper limit.

The 1 and 2 serve for a more detailed explanation of the vehicle systems described here and the method that can be implemented thereby.

The 1 shows an overview diagram of a vehicle electrical system with a first electrical system branch ESYS1 , a second electrical system branch ESYS2 and a third electrical system branch ESYS3 , The first electrical system branch ESYS1 includes a battery E1 as energy storage and a load L1 , as well as an optional generator G1 , In the first electrical system branch ESYS1 controls the vehicle electrical system voltage U1 and a current flows I1 from the or from the first Bordnetzzweig out.

The second board branch ESYS2 includes a second load L2 , as well as an optional generator (second generator G2 ). In the second electrical system branch ESYS2 the tension prevails U2 , A stream I2 flows to the first electrical system branch or away from it.

A third board branch ESYS3 includes a second energy storage E2 as well as a third load L3 that from the energy store E2 is supplied. In the third electrical system branch ESYS3 there is a tension U3 , A stream I3 flows to the third electrical system branch ESYS3 out or away from this.

In the following, the procedure described here is based on the electrical system branches ESYS1 and ESYS2 explained in more detail: The switch K2 (shown as a MOSFET) connects switchable the two electrical system branches ESYS1 and ESYS2 , The desk K1 forms here a controllable connection device. The drive unit M1 is driving with the switch K1 connected and includes a signal generator IG which may also be arranged to deliver a state sequence. The signal generator includes the actuator SG a regulation CTRL includes. A store ME keeps configurable control parameters for the control element at all times CTRL ready, and thus defines the characteristics, the behavior and in particular the transfer function of the scheme CTRL , The memory may include an input or an interface configured to receive at least one control parameter. In this case, for example, in the case of a linear controller, in particular a PID controller, the characteristic control parameters are in the memory ME available retrievable. For a PID controller these are the proportional, the integral and the differential factor.

There is a generally represented feedback FB in such a way that via this an actual state of the first electrical system branch ESYS1 is detected and passed to the scheme, such as the voltage U1 and / or the electricity I1 , Is the voltage below a limit or is the current I1 Over a limit, then it can be concluded that a load condition exists. In this case, via the switch K1 the second electrical system branch ESYS2 connected, in particular by driving the gate of the switch K1 , Here, however, is not switched from an open state directly to a closed state of the switch, but the switch K1 For example, it receives a pulse sequence from the pulse generator before the second switching state (namely K1 = closed) is reached. This exemplary embodiment of a pulse sequence gives a continuous, quasi-continuous or stepwise closing of the switch K1 again, but does not correspond to a direct transition between the off state and the on state of the switch K1 , The control CTRL gives this to the actuator SG or the pulse generator IG , the actuator comprises (or realizes) an actuating signal, which is formed according to the implemented control. For example, depending on the voltage U1 , the pulse width or the duty cycle (starting from 0) are increased until the second stable switching state, ie a closed switch K1 , permanently yields. This then corresponds to the second switching state. By closing the switch K1 , which is achieved by the pulse sequence, the voltage increases U1 which, for example, by activating the load L1 has dropped and thus the first electrical system branch by the second electrical system branch ESYS2 is to be supported (in particular, provided that the generator provides sufficient energy). As mentioned, this support is achieved by connecting the second board network branch ESYS2 by means of the switch K1 achieved, for example, but for safety reasons quickly but not switched on abruptly, but the switch K1 For example, according to the pulse sequence mentioned here (emitted by the pulse generator or the actuator SG ).

The control signal at the beginning of the control or regulation can, for example (regardless of whether the connecting device K1 . K2 closed or open in the first switching state) as a maximum input parameter (eg, maximum duty cycle), a minimum input parameter (eg, minimum duty cycle), or a variable input parameter between the maximum input parameter and the minimum input parameter.

For example, as a load L1 the starter of an internal combustion engine be provided while the generator G1 represents an alternator. When activating this load L1 results in a voltage dip of the voltage U1 or a particularly high current I1 to the first electrical system branch ESYS1 towards, for example, starting from a third Bordnetzzweig ESYS3 , For example, the electrical system branch ESYS3 To protect against a voltage dip, the second electrical system branch ESYS2 by means of the switch K1 switched on, further wherein the switch K2 , which the second Bordnetzzweig ESYS2 with the third electrical system branch ESYS3 connects, for example, according to the one mentioned here Pulse sequence can be switched. This can be seen, in that both the switch K1 as well as the switch K2 from the drive unit M1 is controlled. Because the switch K2 According to the pulse sequence, from the stable closed state to the stable open state, according to the pulse sequence, there is no high transient in the current I3 ; Rather, this is the third electrical system branch ESYS3 transferred by a continuous or at least gradual transition in a car operation ( K2 open) . For example, if the load L3 is sensitive to current transients, then can be prevented by the current transients generated in ESYS1 on the system ESYS3 pass.

It is shown that the memory ME has at least one entry, a control parameter for the control CTRL represents. This is represented by the lower arrow, which is from ME goes out, which of the memory ME in the control element CTRL shows. Alternatively or in combination with this, in the memory ME the pulse sequence itself be occupied or values that characterize them in their course of the value itself, in which case the pulse generator according to the ME controlled values themselves (and not the regulation according to the control parameters of ME is performed) . This can be regarded as a control, since the course of the manipulated variable or the course of the pulse sequence is predetermined and is carried out substantially independently of external variables. It can, however, be considered feedback FB about the tension U1 or the stream I1 the drive unit M1 be fed to one of several in the store ME to select different pulse sequences according to the magnitude of the overload condition. Thus, at a first voltage dip of the voltage U1 which is stronger than a second voltage dip of the voltage U1 another pulse sequence of the memory ME be selected as at the second voltage dip. It can be provided a device which determines the stronger voltage dip or generally the overload state in the first electrical system branch and, accordingly, the pulse sequence of a plurality of pulse sequences in the memory ME selects.

The memory ME has an entrance EGG via which the pulse sequence and in particular at least one input parameter which defines the regulation or control are input to the drive unit M1, in particular in the memory ME , As a result, for example, an entry in memory ME be overwritten or written in general, which comes from an external unit. This allows an adaptation of the drive unit M1 from the outside. Alternatively, the entrance EGG also directly specify the values to the pulse generator or to the control or regulation CTRL to define the current regulation directly from the outside.

A power converter DC / DC connects the third electrical system branch ESYS3 with the first electrical system branch ESYS1 , This is also from the drive unit M1 driven. The power converter DC / DC may for example be a DC / DC converter comprising at least one switch and at least one temporary energy storage such as a coil or a capacitor, so as to form a transducer, in particular an up or down converter, for example a synchronous converter. The at least one switch of the power converter DC / DC defines, in particular, the output current and / or the output voltage of the power converter and is also provided by the drive unit M1 driven. This gives the power converter the opportunity to increase or decrease the power, the current or the voltage according to a continuous or quasi-continuous ramp or according to at least one or more stages until the converter has reached a steady state, in particular when switched on or off corresponds to the second stable switching state. The power converter DC / DC can be controlled, in particular by means of the control element CTRL , which by means of feedback FB considers the effects of the change in the converter as an actuator, ie the change in the current I1 and / or in tension U1 ,

1 serves to explain the support of the first electrical system branch ESYS1 , but also in the same way to support the electrical system branch ESYS2 or ESYS3 serve, depending on the respective loads and the intended applications.

The 1 describes the parallel connection of energy storage, resulting in a power distribution for the loads in terms of energy storage.

The 2 represents a simplified circuit diagram, is connected in series. This is in 2 a vehicle electrical system shown, which has a first electrical system branch ESYS1 and a second electrical system branch ESYS2 includes. Since these the first and second Bordnetzzweigen the 1 may correspond, the same reference numerals have been chosen. The electrical system branches ESYS1 and ESYS2 are in the 1 shown simplified, in particular in which only the energy storage E1 and E2 the two Bordnetzzweige are represented, together with the load L1 of the first electrical system branch. Weight L1 may be provided, for example, by a starter of an internal combustion engine, the first of the energy storage E1 (about a battery) is fed. First, the second electrical system branch ESYS2 from the first electrical system branch ESYS1 be disconnected, in particular in which the switch S1 is open. Here is the switch S2 closed. Will the load L1 activated, the voltage of the energy source decreases E1 , which has an internal resistance as a real voltage source, which means that at high currents, the voltage in the first electrical system branch ESYS1 breaks. This corresponds to an overload condition. To prevent this, for example in order to prevent other loads in the first electrical system branch from being disturbed by this, the second on-board network branch becomes ESYS2 connected, in 2 in a serial way. This is the switch S1 closed and the switch S2 is opened (as shown), so that the energy storage E1 and E2 are connected in series. This results in a voltage addition of the energy storage E1 and E2 , The energy storage E2 may be about a battery, in particular with a much smaller capacity than the battery E1 , or may be realized by a capacitor or a capacitor bank.

For controlling the switch S1 and S2 becomes the drive device M1 used. This controls the switches S1 and S2 in accordance with the pulse sequences described herein to allow for a continuous or at least gradual transition between open and closed switching states. The switches S1 and S2 each have an end that with the energy storage E1 connected is. This results in a serial circuit. Thus, each one end of the two switches S1 and S2 connected with each other. The other ends lead to different potentials, namely on the one hand to the positive potential of the energy storage E2 (via the switch Sl), and on the other hand to the ground potential via the switch S2 , This results in a serial circuit. The switches S1 and S2 together form a switch and are alternately opened or closed. By means of the switch shown thereby, the reference potential can be selected, to which the negative terminal of the battery E1 is placed. Normally, this is mass, while in the overload case and thus in the case of support, the positive pole of the battery E2 is.

As nominal values for the control (in 1 : CTRL ), the voltages shown, the currents shown or even sums all or only part of all voltages or currents are. Furthermore, the product of the current and the voltage on or in a vehicle electrical system branch can serve as the nominal value. The same applies to the actual size of the controller (in 1 : CTRL ), wherein the corresponding sizes can be detected in the usual way. In particular, as a target or actual size for the scheme, the transferred power of ESYS3 to ESYS2 serve the performance in ESYS1 or a zero current in two subnets (for example I1 + I2, I1 + I3, I2 + I3, I1-I2). In addition to these combinations, the mentioned quantities can also be used individually as desired and actual parameters. The mentioned power results from the voltage within a vehicle electrical system multiplied by the current flowing out of an electrical system branch or flowing into it. Furthermore, other parameters can be used alternatively or in combination herewith as control variables, for example the temperature and / or an aging state of the energy stores, the loads and / or the switches K1 . K2 or the DC / DC converter.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been 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.

Cited patent literature

• DE 102014208257 A1 [0003]

Claims (12)

Method for operating a vehicle electrical system with multiple on-board network branches (ESYS1, ESYS2, ESYS3), with the following steps: Detecting an overload state in a first on-board network branch (ESYS1) and Connecting at least one second vehicle electrical system branch (ESYS2, ESYS3) to the first vehicle electrical system branch (ESYS1) when the overload condition has been detected, the connection comprising: changing a switching state of at least one controllable connection device (K1, K2) from a first switching state to a second switching state, wherein the connection device (K1, K2) is switched according to a transition drive signal when changing the switching state before reaching the second switching state. Method according to Claim 1 wherein the switching state of at least one linear transistor (K2) or a power converter (DCDC) is formed, which forms the connecting device. Method according to Claim 1 or 2 wherein the transition drive signal according to which the connection device (K1, K2) is switched has a duty cycle, a frequency and / or an amplitude which is the control variable (CTRL). Method according to Claim 3 wherein the control or regulation (CTRL) defines a time course of the change of the switching state, which is given by a predetermined dependence of the duty cycle, the frequency and / or the amplitude of the time, or by at least one input parameter of the controller or the control given is. Method according to one of the preceding claims, wherein at least one input parameter of the transition drive signal is a manipulated variable of a linear regulator (CTRL), which regulates the transition between the first switching state and the second switching state. Vehicle on-board network with a first and a second on-board network branch (ESYS1, ESYS2, ESYS3) and at least one controllable connection device (K1), which is set up to connect the second on-board network branch (ESYS2) to the first on-board network branch (ESYS1) by changing between a first switching state and a second switching state, wherein the vehicle electrical system comprises a drive unit (M1) which is drivingly connected to the controllable connection device (K1; K2) and is set up, the at least one connecting device (K1; K2) when changing the switching state before reaching the second Switching state according to a transition drive signal to switch. Vehicle electrical system to Claim 6 , wherein the connecting device is designed as at least one power converter (DCDC) and / or as a linear transistor (K2). Vehicle electrical system to Claim 6 or 7 wherein the drive unit (M1) comprises a signal generator (IG) adapted to output the transition drive signal, the signal generator (IG) comprising at least one actuator (SG) of a control element (CTRL), wherein the actuator (SG) is established is to set a duty cycle, a frequency and / or an amplitude as a manipulated variable of a control or control provided by the control element (CTRL). Vehicle electrical system to Claim 6 or 7 , wherein the drive unit (M1) has a signal generator (IG), which is connected to a writable memory (ME) of the drive unit (M1), wherein in the memory (ME) at least one input parameter is stored, the temporal course of at least one Size indicating the transient drive signal reflects. Vehicle electrical system to Claim 9 wherein the input parameter is configured as a control parameter configured to compare with an actual state value of the connection device (K1; K2) or as a configuration parameter configured to set the connection device (K1; K2). Vehicle electrical system to Claim 6 or 7 wherein the drive unit (M1) comprises a linear regulator (CTRL) which adjusts a pulse width, a duty cycle, a frequency or an amplitude of the transition drive signal. Vehicle electrical system to Claim 11 , wherein the linear controller (CTRL) is a PID controller whose actuator is formed by the signal generator (IG), and whose control parameters are stored in a memory (ME) overwritable or can be input to an input (EI) of the drive unit.

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