WO2014121995A2

WO2014121995A2 - Method for operating an energy supply unit for an on-board power system of a motor vehicle

Info

Publication number: WO2014121995A2
Application number: PCT/EP2014/050813
Authority: WO
Inventors: Stephan Mietens
Original assignee: Robert Bosch Gmbh
Priority date: 2013-02-11
Filing date: 2014-01-16
Publication date: 2014-08-14
Also published as: CN104969439B; DE102013202197A1; KR102231539B1; KR20150116843A; CN104969439A; WO2014121995A3

Abstract

The invention relates to a method for operating an energy supply unit (100) for an on-board power system (30, 31) of a motor vehicle, wherein the energy supply unit (1) has an electrical machine (20) with a stator winding (21) and a rotor winding (22), a generator regulator (40) which is assigned to the rotor winding (22) and has the purpose of presetting the current flowing through the rotor winding (22), and a rectifier (30) with rectifier elements, wherein an imminent change in configuration of the on-board power system (100) is signalled and in response the magnitude of the current flowing through the rotor winding (22) is changed.

Description

Description title

Method for operating a power supply unit for a vehicle electrical system of a motor vehicle

The present invention relates to a method for operating a power supply unit for a vehicle electrical system of a motor vehicle and a computing unit for performing the same.

State of the art

A generator arrangement for motor vehicle electrical systems can have a third-party, electrical machine (in particular an alternator) with a rotor winding (excitation winding) and a stator winding, a rectifier connected downstream of the stator winding (in general a rectifier) and a generator regulator (so-called field regulator), which generates the electric motor generated by the electric machine Voltage by means of the current (excitation current) through the rotor winding regulates. Such generator arrangements are used in different forms in motor vehicle on-board networks.

As explained, for example, in DE 10 2009 046 955 A1, the use of active bridge rectifiers is advantageous for rectification because, in contrast to passive or uncontrolled diode rectifiers, they have lower power losses.

The control of the excitation current, the output voltage can be controlled to ensure the operation of the electrical system. The task of the voltage regulation is to maintain the vehicle electrical system voltage at a constant level in the event of strongly changing generator speeds and different loads to keep. The control speed is limited by the time constant of the rotor winding, which is in the order of several 100 ms. With a sudden load dump (load dump) in the electrical system, for example by switching off a larger consumer, it comes first to a significant increase in the generator voltage, since the regulation of the voltage across the excitation current can only be done with a corresponding time delay. At higher speeds and the release of a larger load, inadmissibly high voltage values can occur. These voltage spikes can damage electronic components and lead to failure of ECUs.

In contrast to diode rectifiers, in which an overvoltage protection usually takes place through the rectifier diodes themselves, because there the loss energy can be converted into heat, for conventional active switching elements, such as MOSFETs, additional protection strategies are required.

For a load shedding, for example, some or all switching elements of the upper or lower rectifier branch can be short-circuited completely or temporarily, as also discussed, for example, in the mentioned DE 10 2009 046 955 A1. A corresponding drive signal can be clocked in such a way that a minimum voltage level does not fall below and a maximum

Voltage level is not exceeded. However, multiple clocking of the drive signal within one half-cycle has disadvantages because, for example, this an evaluation circuit for each phase required and to maintain the vehicle electrical system voltage a corresponding DC link capacity is provided.

While in conventional 12V batteries, a voltage clamping effect arises from the fact that excess energy is converted into chemical energy (so-called outgassing), in modern batteries (for 12V or 48V vehicle electrical systems or high-voltage electrical systems with voltages above 60V, for example a few 100V (eg 300-400V)) lithium-based (eg lithium-ion) a too high voltage level problematic and to avoid. Such batteries are therefore automatically disconnected from the electrical system overvoltage via a corresponding circuit and can not serve as surge protection. Similarly, too low a voltage level is critical here, which is why Even with undervoltages can be done automatically disconnection from the electrical system.

It is therefore desirable, even in on-board networks with active power converter circuits and at the same time separable batteries the simplest possible Überbzw. To provide undervoltage protection.

Disclosure of the invention

According to the invention, a method for operating a power supply unit for a vehicle electrical system of a motor vehicle with the features of patent claim 1 is proposed. Advantageous embodiments are the subject of the dependent claims and the following description.

Advantages of the invention

The invention provides an easy way to reduce over or under voltages in the electrical system or completely suppress by an impending configuration change of the electrical system of the power supply unit is reported and then the height of the exciter field or the effective excitation current is reduced or increased accordingly. Thus, preferably, a reduction or increase in the height of the exciter field is already initiated before the configuration change takes place. A configuration change is in particular a reduction or increase of energy consumption and / or disconnection or connection of an energy storage device, in particular a battery, from or to the on-board network.

Configuration changes of the vehicle electrical system, such as reducing or increasing the energy consumption, for example by turning on or off a consumer or gradual increase or decrease in power consumption (eg heating), or disconnecting or connecting the energy storage device, are usually by appropriate control units (eg control unit for the vehicle electrical system management or control unit for the battery charging management), so that the invention can be easily cation of these control units can be implemented with the generator controller. The control units now report the forthcoming configuration change, preferably with a lead time, to the generator controller, which then adjusts the exciter field accordingly, ie reduces it at an expected overvoltage due to the configuration change and increases it at an undervoltage due to the configuration change. The lead time is preferably between 300 and 500 ms. When specifying the lead time, the time constant of the rotor winding and data transmission and / or processing times are preferably taken into account. As a result, voltage fluctuations, in particular over- and under-voltages, can be advantageously reduced.

The invention is suitable for all types of vehicle on-board networks, ie in particular for conventional 12V or 48V onboard networks, but also for high-voltage electrical systems with voltages above a permissible contact voltage of 60V. The invention also develops particular advantages in on-board networks in which the electric machine can also be operated by a motor. Here then, e.g. be switched by the invention in good time before a configuration change from a motor to a generator operation.

The amount of reduction and / or the increase of the excitation field can be predetermined, whereby advantageously several values for different situations are given. For example, an expected change in the power output may have been determined in advance as a whole depending on the on-board network, e.g.

500 W as an intermediate value of high-power consumers with 300-800W power consumption, or as 50% of the rated power at battery disconnection or - connection. Further preferably, the amount of reduction and / or the increase of the excitation field in dependence on the expected consumption change is specified. For example, the abovementioned control units also transmit, in addition to the type of the forthcoming configuration change, the associated change in energy consumption or the vehicle electrical system voltage. For this purpose, the control unit controlling the separation and the connection of the energy storage device preferably has measuring means which are designed to determine a current power consumption or output and / or a state of charge of the energy storage device. The current power consumption or output characterizes the change in the energy flow during the

Disconnecting the energy storage device, since the lost energy flow from the energy storage device to consumers (may also include the electric machine in a motor operation) or from the electric machine to the energy storage device must now be compensated by the electric machine. The state of charge compared to the current voltage in the electrical system characterizes the change in the energy flow when connecting the energy storage device, since in a state of charge with a voltage output below or above the vehicle electrical system voltage, the energy flow from the electrical system to the energy storage device or vice versa must be compensated by the electric machine.

The control unit which controls the reduction and increase of the energy consumption preferably has storage means therefor in which information about the usual power consumption of the controlled energy consumers, preferably separated between switch-on operation and continuous operation, is stored.

Conveniently, only high-performance consumers with a rated power of more than 100 W are taken into account.

In accordance with a further advantageous embodiment of the invention, measures are provided if the generator arrangement can not completely avoid an overvoltage or undervoltage caused by the configuration change, for example because the electric machine can not currently provide sufficient current for the vehicle electrical system (eg due to low rotational speed) , Such a measure includes, for example, the reduction or increase of the instantaneous power consumption by the consumers, in particular by appropriate control of the control unit which controls the reduction and increase of the energy consumption. Preferably, a voltage profile model, which distinguishes between power consumers and power consumers in the electrical system and takes into account an inductance of the consumer, is used. As a result, the necessary excitation current change and a possibly provided lead time can be determined more accurately. Further preferably, the voltage profile model also takes into account an inductance of the electrical machine in order to optimally suppress voltage fluctuations. For example, the excitation current can then be specified so that effects of the respective inductances of the electrical machine and consumers are virtually eliminated and the voltage is kept almost constant.

An arithmetic unit according to the invention, e.g. a control device of a motor vehicle, in particular a field controller and / or one of said control units is, in particular programmatically, arranged to perform a method according to the invention.

The implementation of the method in the form of software is also advantageous, since this causes particularly low costs, in particular if an executing control device is still used for further tasks and therefore exists anyway. Suitable data carriers for providing the computer program are, in particular, floppy disks, hard disks, flash memories, EEPROMs, CD-ROMs, DVDs and the like. It is also possible to download a program via computer networks (Internet, intranet, etc.).

Further advantages and embodiments of the invention will become apparent from the description and the accompanying drawings.

It is understood that the features mentioned above and those yet to be explained below can be used not only in the particular combination indicated, but also in other combinations or in isolation, without departing from the scope of the present invention. The invention is illustrated schematically with reference to an embodiment in the drawing and will be described in detail below with reference to the drawing. Brief description of the drawings

Figure 1 shows schematically an electrical system of a motor vehicle, as it may be based on the invention. Embodiment (s) of the invention

1 shows a vehicle electrical system according to a preferred embodiment of the invention is shown and designated 100 in total. The vehicle electrical system 100 has as an energy supply unit a generator arrangement 1 with an electric machine which can be operated as an AC current generator 20 with a stator winding 21 and a rotor winding 22. The rotor winding 22 is energized by means of a generator regulator or field controller 40, preferably clocked. The alternator 20 may be formed, for example, as a claw pole generator. The generator assembly further comprises a power converter or rectifier 30, which is designed to rectify an AC voltage generated by the AC generator and to provide as vehicle electrical system voltage at terminals B + and B-. The rectifier 30 has active switching elements, e.g. MOSFET, and is operated in a known manner. The generator assembly 1 or the power converter 30 has for this purpose a current richtersteuer- unit (not shown). The power converter can also be operated as an inverter for a motorized operation of the electrical machine.

In the vehicle electrical system 100 is an energy storage 2, for example, a lithium-based battery, provided to save in particular the fed by the generator assembly 1 in the electrical system 100 electrical energy. The battery

2 is preceded by a battery charge control unit 3, which is adapted to disconnect the battery in the event of an overvoltage and / or undervoltage in the electrical system of this and / or a disconnected battery back to the electrical system, if there is no overvoltage or undervoltage. The separation and the Switching on the battery 2 controlling battery charging control unit 3 is further configured to report an impending disconnection or connection process as a configuration change of the on-board network 100 to the generator controller 40, so that this accordingly the current through the rotor winding 22 sen influence, ie reduce or increase , In this sense, the battery charging control unit 3 is operated as an overvoltage or undervoltage detection unit. In this case, the separation process is preferably delayed in order to still obtain a certain overvoltage protection by the battery. However, the separation process can also take place without delay. Likewise, the connection process is delayed in order not to generate overvoltage. However, the connection process can take place without delay. The battery charging control unit 3 is further configured to notify the generator controller 40, along with the impending disconnecting or connecting operation, of the associated change in power consumption. The battery charging control unit 3 has measuring means, for example a voltmeter, a power consumption sensor or a

Charge state sensor, which are designed to determine a current vehicle electrical system voltage and a current power consumption or -abgäbe and / or a state of charge of the battery 2. From these quantities, the change in the energy flow associated with the upcoming separation or connection process can be determined. In particular, the battery charging control unit 3 knows the current that flows into or out of the battery. This current flow will end with the separation. As a consequence, this basically means that the current must be provided by a generator operation of the electric machine in the same height and direction.

Consumers 6 are also integrated into the vehicle electrical system 100, in particular high-power consumers, such as a window heating, auxiliary heating, seat heating, air conditioning, etc. The consumers can be switched on and off, as illustrated by switching elements 7, and can possibly also be varied in their power consumption , which is illustrated by the arrow 8. An on-board network control unit 9 is set up to control the consumers 6. The on-board network control unit 9 which controls the reduction and increase of the energy consumption is furthermore set up to report an imminent control of a consumer 6 as a configuration change of the vehicle electrical system 100 to the generator controller 40. so that it can accordingly affect (ie, reduce or increase) the current through the rotor winding 22. In this case, the imminent control of the consumer is delayed in order to at least reduce overvoltages and undervoltages. The onboard power supply control unit 9 is further configured to notify the generator controller 40 together with the imminent control of the consumer and the associated change in energy consumption. The on-board network control unit 9 has storage means, for example a microprocessor and non-volatile memory, in which information about the average power consumption (for variable power consumption, preferably for different power levels) of the controlled

Energy consumers 6 are stored in continuous operation and the power-on.

An upcoming configuration change may also involve a switchover from motor operation to generator operation of the electrical machine, e.g. to reduce undervoltage.

Claims

claims

1 . Method for operating a power supply unit (1) for a

Vehicle electrical system (100) of a motor vehicle,

wherein the power supply unit (1) comprises an electric machine (20) having a stator winding (21) and a rotor winding (22), a generator controller (40) associated with the rotor winding (22) for specifying the current flowing through the rotor winding (22) and a power converter (30) having power converter elements,

wherein an imminent configuration change of the electrical system (100) to the power supply unit (1) is reported and then the height of the current flowing through the rotor winding (22) current is changed, wherein the configuration change of the electrical system (100) disconnecting and / or connecting an energy storage device (3), in particular a battery, from or to the electrical system (100).

2. The method of claim 1, wherein the configuration change of the electrical system (100) comprises reducing and / or increasing energy consumption by a consumer (6) in the electrical system (100).

3. The method of claim 2, wherein the configuration change of the electrical system (100) comprises switching off or switching on the consumer (6).

A method according to any one of the preceding claims, wherein the amount of current flowing through the rotor winding (22) is reduced when an overvoltage is expected due to the configuration change.

5. The method according to any one of the preceding claims, wherein the height of the current flowing through the rotor winding (22) current is increased, if due the configuration change an undervoltage is expected.

6. The method according to any one of the preceding claims, wherein the configuration change of the electrical system (100) is carried out a lead time after the message.

7. The method of claim 6, wherein the lead time as a function of a time constant of the rotor winding (22) is specified and / or wherein the lead time between 250 ms and 750 ms.

A method according to any one of the preceding claims, wherein the magnitude of the current flowing through the rotor winding (22) is varied by a variation value and the variation value is given in dependence on the configuration change.

9. The method according to any one of the preceding claims, wherein a lithium-based battery is used as energy storage device (3).

10. The method according to any one of the preceding claims, wherein the reported imminent configuration change of the electrical system (100) toward a power consumption by a consumer (6) in the electrical system (100) is reduced or increased.

1 1. Method according to one of the preceding claims, wherein the height of the current flowing through the rotor winding (22) current is changed taking into account an inductance in the electrical system (100).

12. arithmetic unit (40, 3, 9) which is adapted to perform a method according to any one of the preceding claims.

13. Computer program which is set up to perform all the steps of the method according to one of claims 1 to 11.

14. A machine-readable storage medium with a computer program stored thereon according to claim 13.