DE102018008603A1 - Circuit arrangement and method for charging a battery arrangement with a plurality of battery modules - Google Patents

Abstract

The present invention relates to a circuit arrangement (10) for charging a battery assembly (12) with a plurality of battery modules. For this purpose, it is first determined which terminal of the circuit arrangement (10) is live and which terminal is designed as a neutral conductor (N). For this purpose, a voltage measurement is performed between the protective conductor (PE) and one of the two terminals of the circuit arrangement. Alternatively or additionally, a voltage measurement between a center tap (M) and one of the two terminals of the circuit arrangement (10) can be used to determine. In a further step, a first, second, third and fourth switching element of the circuit arrangement (10) can be controlled in such a way that one of the battery modules of the battery arrangement (12) is charged, while at the same time another battery module of the battery arrangement (12) is not charged. In this case, the second switching element (S2) and the fourth switching element (S4) can be operated clocking in order to realize a predetermined potential difference via a respective battery circuit.

Description

The present invention relates to a circuit arrangement and method for charging a battery assembly with a plurality of battery modules. Moreover, the invention relates to a method for charging a battery module in a battery assembly.

In galvanically coupled charging, it is often desirable to avoid potential jumps in the high-voltage system. As a result, leakage currents can be avoided via so-called Y capacitances, which would cause a circuit breaker (FI type A) to trip. Applicant, various approaches are known, which have been used to avoid these potential jumps in the high-voltage system. The range of power electronics with the jumping high-voltage potential can be kept small and be galvanically separated from the rest of the vehicle by a transformer. This is a common construction of a on-board loader. After the transformer, the reference potential can be freely selected again.

Another concept provides that in the case of a galvanically coupled charging system, the leakage current is measured via the Y capacitances and a compensating current is fed to the leakage currents via a current source.

Another solution provides that the high-voltage negative potential and then the high-voltage plus potential are adjusted to a constant value over time by two voltage transformers connected in series. In these solutions, however, either a galvanic isolation must be realized or with a required PFC functionality, a circuit must be designed for the full battery voltage.

The publication US 2013/0094255 A1 describes a power factor correction circuit capable of predicting an input current level. The power factor correction circuit and associated control method use a power factor control to generate a compensation current signal according to an input voltage of an AC-DC converter device and a filter capacitor value.

The publication DE 10 2011 077 701 A1 describes a vehicle battery with multiple voltage levels and a method for operating a vehicle battery with multiple voltage levels. A battery case has a plurality of serially coupled battery cell blocks. The battery cell blocks are arranged in a battery case. These each comprise at least one battery cell. The vehicle battery has a plurality of first pole terminals which are respectively connected to a node between the serially coupled battery cell blocks and which are led out of the battery case. Further, the vehicle battery has a plurality of second pole terminals which are connected to the end taps of the vehicle battery. In this case, a plurality of voltage levels depending on the lying between the two pole terminals battery cell blocks can be tapped. This is possible on two of the first and second pole connections.

It is an object of the present invention to provide a circuit arrangement which enables a more efficient or improved charging of a battery.

This object is solved by the independent claims of this application meaningful. Alternative embodiments and further examples emerge from the subclaims, the description and the figures.

The invention provides a circuit arrangement for charging a battery arrangement with a plurality of battery modules. In many cases, the battery assembly will have exactly two battery modules, but a battery assembly may contain well over two battery modules. The circuit has a rectifier for transforming an alternating current into a direct current. The circuit arrangement has a first line section which is connected to the rectifier in series at a first output of the rectifier, wherein the first line section has a first inductance, a first switching element parallel thereto and a first battery circuit connected in series with these. In this case, the first inductance can be bridged by means of the first switching element and the first battery circuit has a first parallel connection. This parallel circuit has a second switching element in a first branch and a first battery module in a second branch parallel thereto.

The circuit arrangement further has a second line section connected to the rectifier in series at a second output of the rectifier. The second line section has a second inductance, a third switching element parallel thereto and a second battery circuit parallel to these. In this case, the second inductance can be bridged by means of the third switching element and the second battery circuit has a second parallel connection. The second parallel circuit has a fourth switching element in a third branch and a second battery module in a fourth branch. The circuit arrangement further has a center tap which is located between the first battery module and the second battery module is arranged and connected to the first branch of the first parallel circuit and / or to the third branch of the second parallel circuit. In addition, the circuit arrangement has a control unit which is designed to switch through the first and the second switching element or the third and the fourth switching element for respectively charging one of the two battery modules, depending on a polarity of the alternating current. In particular, the control unit can also switch through the first and the fourth switching element as well as the third and the second switching element for respectively charging one of the two battery modules. Preferably, the control unit can control and switch all switching elements so that a predetermined battery modules or a plurality of predetermined battery modules are charged. With such a circuit arrangement, one battery module can be charged while another battery module is not being charged. Such a circuit arrangement makes it possible to dispense with a galvanic isolation in the on-board charger. This can help to reduce costs and increase efficiency during charging. As can be dispensed with a galvanic separation in the on-board loader, there may also be advantages in terms of weight.

A further embodiment provides a circuit arrangement, wherein the rectifier is connected to a voltage source with a current-carrying conductor, a neutral conductor and a protective conductor. If the alternating current is designed as a high current, the current-carrying conductor can be divided into further current-carrying conductors. In the case of a high current, these may be, for example, three individual live conductors. With the help of the protective conductor, the risk of accidental charging of a vehicle body can be prevented. This makes it possible to safely and reliably charge a battery assembly.

A further embodiment provides that the second branch of the first battery circuit has a first diode and the fourth branch of the second battery circuit has a second diode in order to prevent discharging of the battery modules. Since diodes ideally allow current to flow only in one direction, it is possible to prevent accidental discharging of the battery modules.

Another embodiment provides a circuit arrangement with a connected electrical load and a suppression capacitor, which is connected to the protective conductor. The suppression capacitor can reduce electromagnetic interference. In particular, they can conduct or short-circuit high-frequency interference signals, which are caused by the operation of electrical or electronic equipment, against the ground or the neutral conductor. Thus, a reduction of the electromagnetic interference can be effected. Thus, it can be ensured that even in the case of clocking operated switching elements within the circuit no electromagnetic interference occur or they can be at least reduced.

The invention also provides a method of charging a battery module in a battery assembly. For this purpose, the following method steps are carried out. In a first step a) it is determined which terminal of a circuit arrangement according to one of the preceding variants is live and which terminal is designed as a neutral conductor. This is done by means of a voltage measurement between the protective conductor and one of the two terminals of the circuit arrangement. Alternatively, it can be determined in another way in step a), which terminal of the circuit arrangement according to a variant of the circuit arrangement is designed to carry current and which terminal is designed as a neutral conductor. In this case, the voltage measurement between the center tap and one of the two terminals of the circuit arrangement is carried out in this alternative method step. This makes it possible to determine which connection is connected to the live conductor and which is connected to the neutral conductor.

In a step b), the first, second, third and fourth switching element of the circuit arrangement are driven in such a way that one of the battery modules of the battery arrangement is charged, while at the same time another battery module of the battery arrangement is not charged. In this case, the second switching element and the fourth switching element are operated in a clocking manner in order to realize a predetermined potential difference via a respective battery circuit. Alternatively, it is also possible that all four switching elements can be operated in a clocking manner.

Thus, in a traction battery as a battery arrangement, the center tap can be used as a reference potential. Normally, this reference potential is located in the middle of the two high-voltage potentials and also at the potential of the protective conductor and neutral conductor connection. The normal case represents that case which does not include an isolation error. The circuit arrangement or the galvanically coupled charging system has at Hochvoltplus- and Hochvoltminusanschluss after the rectifier in each case a choke or inductance, which can be operated clocked. This means that the first switching element and the third switching element can be operated in a clocking manner. Furthermore, you can also the second and fourth switching elements are operated in a clocking manner. Thus, it is possible that the control unit can switch all switching elements or predetermined switching elements clocking. In this context, "clocking control" can also mean "switching clocking". In particular, it is thus also possible to control the activation and / or switching of switching elements. Each inductor can thus be switched inactive via a bypass switch. In this case, the first switching element and the third switching element each represent a bypass switch. Depending on the half-wave of the L-terminal alternately the Hochvoltplus- and high-voltage negative terminal of the rectifier is connected to the center tap. The other terminal meanwhile acts as the power correction factor switch via the associated inductance. Likewise, the second switching element and the fourth switching element can be operated in a clocking manner. These clocking switches are arranged parallel to the respective battery module. In method step a), it can be determined which port represents the L port or the N port. In order to identify which connection is assigned to which conductor, the measurements mentioned in method step a) are carried out. An insulation fault can be detected during charging via an FI type B fault circuit breaker.

The examples and advantages described for the circuit arrangement and its various embodiments apply mutatis mutandis to the method and vice versa.

The invention will now be explained in more detail with reference to the accompanying drawings.

Further advantages, features and details of the invention will become apparent from the following description of preferred embodiments and from the drawings. The features and feature combinations mentioned above in the description as well as the features and feature combinations mentioned below in the description of the figures and / or in the figures alone can be used not only in the respectively specified combination but also in other combinations or in isolation, without the scope of To leave invention.

• 1 ein exemplarisches Schaltbild mit Möglichkeit zum Schalten auf eine Zwischenspannung;
• 2 ein schematisches Schaltbild zum galvanisch gekoppelten Laden mit Nutzung eines Mittelabgriffs einer Batterieanordnung;
• 3 Schaltungsanordnung mit Darstellung eines Ladevorgangs während einer positiven Halbwelle, wobei der Neutralleiter am unteren Anschluss der Spannungsquelle angeschlossen ist; und
• 4 Ausschnitt einer Schaltdarstellung zum Darstellen des Mittelabgriffs der Batterieanordnung bei einer Vielzahl von Batteriemodulen.

Showing:

• 1 an exemplary circuit diagram with possibility for switching to an intermediate voltage;
• 2 a schematic circuit diagram for galvanically coupled charging using a center tap of a battery assembly;
• 3 Circuit arrangement showing a charging process during a positive half cycle, wherein the neutral conductor is connected to the lower terminal of the voltage source; and
• 4 Part of a circuit diagram illustrating the center tap of the battery assembly in a plurality of battery modules.

There are various reasons for the use of a galvanically insulating on-board charger. In the event of an insulation fault after the rectification of the AC input voltage, a superimposed DC current is added in addition to the AC charging current at the connection side. This superimposed DC current drives the Type A RCCB into home automation. Thus, this circuit breaker is ineffective. As remedial measures, increased insulation in the area of the charger between the AC rectification and the secondary side of the transformer is known. If the on-board charger were galvanically coupled, for example without downstream galvanically insulating DC / DC converter or with a downstream galvanically coupled DC / DC converter according to the current state of the art, the requirement of increased isolation would be transferred to all components in a motor vehicle , This would affect all components which are galvanically connected to such a charger, such as the vehicle battery, the powertrain and all high-voltage components in the high-voltage vehicle electrical system.

After rectifying the AC mains voltage, the negative voltage potential is relative to the neutral conductor N and the protective conductor PE a negative sine wave. A charger would transmit this negative potential curve to the entire high-voltage system of the motor vehicle. To counteract this, often a galvanically isolated voltage transformer is used. This allows a new reference potential to be selected on a secondary side of the transformer. The negative potential curve would not be transferred to the high-voltage system of the motor vehicle.

Galvanically coupled on-board loaders usually have several components. They are often connected to an AC power source, which may be single-phase or multi-phase. This can be for example a charging station or a house connection. The galvanically coupled on-board charger has a circuit with several components. One component thereof is a power correction filter PFC, which may be single-phase or multi-phase, for example. This power correction filter PFC may have a star connection or a triangular connection. This circuit can be unidirectional or bidirectional. The galvanically coupled on-board charger may include one or more DC / DC converters. For example, a first DC / DC converter to stabilize the high-voltage negative potential to be provided. This can be, for example, a buck, a boost or a buck-boost converter. These transducers can be unidirectional or bidirectional. A second DC / DC converter may optionally be provided. This second DC / DC converter can be used to stabilize the high-voltage output voltage. This second DC / DC converter can also be designed as a buck converter, boost converter or as a buck-boost converter. This second converter can also be unidirectional or bidirectional. These components can form the galvanically coupled charger. For example, a high-voltage vehicle electrical system can be connected to this galvanically coupled charger. For example, a vehicle battery, an inverter or other ancillary units may be included in this high-voltage on-board electrical system. Also electrical consumers such as an air conditioner or an infotainment system of the motor vehicle can be connected to the galvanically coupled on-board charger.

1 shows by way of example a circuit with two selectable voltage levels. The circuit includes a rectifier 14 , a current sensor SS , a sensor for voltage measurement SM , a first inductance L1 , a first throttle D1 , a first resistance R1 , a first battery module BM1 , a second battery module BM2 , a second throttle D2 , a fourth switching element S4 and a first battery circuit B1 and a second battery circuit B2 , This circuit is connected to an AC input voltage. This can be for example a charging station or a house connection. The basis for the principle of this circuit is a battery assembly 12 , which consists of two battery circuits B1 and B2 consists. The connection of the respective battery circuits B1 and B2 is accessible via a connection. This connection is conductively connected to the semiconductor switches. In the example of 1 are the second switching element S2 and the fourth switching element S4 the semiconductor switches. The positive and negative pole of the battery assembly 12 is via a respective diode with the second switching element S2 and the fourth switching element S4 connected. Preferably, the two diodes D1 and D2 aligned so that at a charging current of the battery modules BM1 and BM2 they are senior. In a discharge current of the battery modules, the two diodes are preferably arranged so that they are aligned. A second connection side of these horizontally illustrated diodes D1 and D2 is via the second switching element S2 and the fourth switching element S4 connected. Using the second switching element S2 , the fourth switching element S4 (Semiconductor switch shown vertically) and by means of the tap between the two battery modules BM1 and BM2 can be achieved that at the battery-side connection point to the first inductance (PFC choke) can be set in two levels adjustable counter-voltage. So can at the first battery circuit B1 a first counter voltage can be adjusted and on the second battery circuit B2 a second different counter voltage can be set.

Instead of two battery modules also several battery modules can be used. In this case would be between the first battery circuit B1 and the second battery circuit B2 arranged further battery circuits. Thus, the battery assembly 12 have more than two battery modules. The respective counter-stresses can be designed differently. However, within the framework of identical-part strategies and simplified control, it makes sense to design the individual battery modules or cells in the same way. This particular battery modules are addressed, which each have the same counter tension. This can be achieved, for example, by using the same or identical battery module in each battery circuit.

2 shows an example of a circuit arrangement 10 , which with the battery assembly 12 a consumer 16 and a suppression capacitor 18 connected is. The circuit arrangement 10 contrary to the circuit of 1 the first switching element S1 and third switching element S3 on which the respective inductances L1 and L2 can bridge. The battery arrangement 12 is according to 2 through a center tap M with the circuit arrangement 10 connected. The consumer 16 points in the example of 2 a third resistance R3 and a capacity CX on. The suppression capacitor 18 points in the case of 2 a positive one Y -Capacity Cy + , a negative Y -Capacity Cy - and a fourth resistor R4 and a fifth resistor R5 on. The circuit arrangement 10 is in the case of 2 using the L-conductor, the neutral conductor N as well as the protective conductor PE connected to the voltage source.

The circuit arrangement 10 can be divided into different line sections. So includes a first line section A1 the first switching element S1 , the first inductance L1 , the second switching element S2 and the associated first battery circuit B1 , Accordingly, a second line section includes A2 the second battery circuit B2 , the fourth switching element S4 as well as the second inductance L2 and the third switching element S3 , When operating the circuit arrangement 10 It is advantageous first to determine which connection from the voltage source of the neutral conductor N is, and which of these terminals is the current-carrying conductor L is. This can be done, for example, by using a Measurement of the voltage between the protective conductor PE and one of the two connections of the mains connection. The two connections of the mains connection are in this case the neutral conductor N as well as the current-carrying conductor L ,

Alternatively or additionally, the voltage between one of the network connections and the center tap M the battery arrangement 12 be measured. For example, the voltage between L and M such as N and M in 2 serve to identify the respective connections. The one connection where the voltage measurement 0 Volts would be the neutral N , the other connection would accordingly be the live conductor L , In this voltage measurement, the two switching elements S2 and S4 preferably open and / or not in 2 shown further battery contactors would be open. Also, a voltage measurement between a first port N1 and a third port N3 or between a second connection N2 and the third port N3 reveal which of the two ports N1 or N2 the neutral conductor N and the live conductor L is.

The one connection where the voltage measurement 0 Volt is the neutral N , the other terminal is accordingly the live conductor L , Likewise, a voltage measurement between the first port N1 and a fourth connection N4 or between the second connection N2 and the fourth connection N4 show which connector of the two connectors N1 and N2 the neutral conductor N or the current-carrying conductor L is. It is important to determine which mains connection the neutral conductor N is to know in the course of the charging process, the correct reference potential and to avoid skipping the high-voltage potential with respect to the vehicle body.

Starting from an AC charging connection (AC charging connection), the alternating current is first rectified. Using the rectifier 14 Thus, an alternating current is converted in a direct current. At the positive pole of the output of the rectifier 14 is the first inductance L1 arranged, which via the first switching element S1 can be bridged. The first switching element S1 can be designed as a semiconductor switch. The same arrangement is analogous using the second inductor L2 and the third switching element S3 at the negative terminal of the rectifier output of the rectifier 14 arranged. The battery arrangement 12 has the center tap M , This battery arrangement 12 in particular, at least two equal-sized battery modules BM1 and BM2 respectively. Each of these battery modules each has its own switch (second switching element S2 for battery circuit 1 , fourth switching element S4 for second battery circuit B2 ). These two mentioned switching elements can preferably be operated clocking. Preferably, each battery circuit has a freewheeling diode. The combination of the diode D1 , the second switching element S2 and the first inductance L1 can be used as a boost converter and for PFC functionality. In particular, PFC functionality means that the function of a power factor correction filter can be provided. This can mitigate negative consequences of pulse-like voltage or current peaks. Excessive current loads can be mitigated by using the PFC functionality.

3 schematically shows two different current waveforms during a charging process using the circuitry 10 , The upper output of the rectifier 14 is in the case of 3 the positive connection of the rectifier 14 , the lower output of the rectifier 14 is in the case of 3 the negative connection of the rectifier 14 , In the example of 3 is the lower terminal of the AC power source of the neutral N and the upper terminal has a voltage between 0 volts to the peak voltage. The first switching element S1 is open while the fourth switching element S4 closed is. Also, the third switching element S3 in the example of 3 closed. The second switching element S2 can in the case of 3 be operated clocking. In general, the potential of the vehicle body in the middle of the two high-voltage potentials. For example, in a motor vehicle having an 800 volt battery, the high voltage potential would be at +400 volts, the high voltage negative potential at -400 volts, and the vehicle body at 0 volts. This can be done in particular by the suppression capacitor 18 ( Y Capacities) and insulation resistances are achieved, which are usually symmetrical. When charging, the vehicle body (chassis) with the neutral conductor N connected. The neutral conductor N is often referred to as neutral. Has the battery arrangement 12 via a medium voltage tap (center tap M ), so its potential is also at 0 volts. This possibility can be used to have a defined reference potential in the respective positive or negative half-wave of the alternating current. The following describes different charging scenarios. It should be noted that 3 only shows the correct current flow for one of these charging scenarios. Due to changing reference potentials at the voltage source as well as differently connected switching elements, other current characteristics may result.

In 3 is an example of a current waveform in the freewheeling phase SVF and a current waveform during the reactor current buildup SVD located. These two current curves represent a first state of charge. According to 3 it is clear that the second switching element S2 , which is operated clocking, the current changes. In particular, this results in the two different current profiles. In the example of 3 become the fourth switching element S4 and the third switching element S3 closed. This will be the negative output of the rectifier 14 with the center tap M connected. This results in the second line section A2 a connection from the negative output of the rectifier 14 to the middle tap M , The second battery circuit B2 is bridged and thus without power. The second diode D2 prevents a short-circuit discharge current from the second battery circuit B2 , The first switching element is in the case of 3 open, that is the coil (first inductance L1 is now included in the power transmission path). The second switching element is operated clocking, so that the arrangement consisting of the first inductance L1 , the first switching element S1 and the first diode D1 a boost converter is shown. This boost converter forms together with the rectifier 14 a PFC circuit. Thus, a power correction filter circuit can be realized. During the charging process, the potentials of high-voltage plus and high-voltage minus are relative to the neutral conductor N always at a constant value. That means the potentials within the battery arrangement 12 always have a constant value. This is done by the boost converter or together with the rectifier 14 realized PFC circuit allows. This allows a leakage current through the Y capacitances Cy + and Cy - be avoided. This would cause a residual current circuit breaker to trip, which is undesirable. In the example of 3 the second battery circuit or the second battery module is not charged. Of course, it is possible that in addition to the reference voltages of 0 volts, +400 volts and -400 volts shown here, other voltage quantities can be used.

In the case of the negative half-wave and the neutral conductor at the lower connection of the AC voltage source, the charging process is different than in 3 is shown. This represents a second loading. In this case, the second switching element S2 and the first switching element S1 closed. This will be the positive output of the rectifier 14 connected to the center tap. This results in the first line section A1 a connection from the positive output of the rectifier to the center tap M , the first battery circuit B1 is bridged and thus without power. The first diode D1 prevents a short-circuit discharge current of the first battery circuit B1 or the first battery module BM1 , The third switching element is open in this case, that is, the coil or second inductor L2 is now integrated in the path of power transmission. The fourth switching element S2 is operated clocking, so that consisting of the second inductance L2 , the fourth switching element S4 and the second diode D2 a boost converter is shown. Together with the rectifier 14 gives this boost converter a PFC circuit. Using this PFC circuit, the second battery module BM2 Loading. During charging, the potentials of the battery assembly 12 of high voltage plus and high voltage minus always referring to the neutral conductor N always at a constant value. In this case, the potentials are -400 volts, 0 volts and +400 volts. Thus, the leakage current through the Y-capacitances can be avoided, which would cause a residual current circuit breaker to trip. The first battery module BM1 will not load.

This second charging process results from the first charging of 3 by the first line section A1 and the second line section A2 be reversed. During the second charging process during the negative half-wave and the neutral conductor N at the lower terminal of the AC power source, the switching elements are switched so that the first battery module BM1 is always bridged and using the fourth switching element S4 the second battery module can be charged. It is also like in 3 realized a PFC circuit, which is in the range of the battery assembly 12 can produce constant voltage levels. In this second charging process, the current flow in the freewheeling phase SVF capture the second battery module. In case of 3 this is for the first battery module BM1 applicable.

Another third charging occurs in the case of a positive half-wave, the neutral conductor N is arranged at the upper terminal of the AC voltage source. Due to the rectifier 14 is the alternating current as in the case of 3 rectified. This results in particular immediately after the rectifier 14 or between the rectifier 14 and the first and second inductance the same current waveform as in the first charging. This applies both to the current flow in the freewheeling phase SVF as well as for the current flow during the reactor current build-up SVD , During this charging process (positive half-wave, neutral N at the upper terminal of the AC voltage source) become the third switching element S3 and the fourth switching element S4 closed. This will cause the negative output of the rectifier 14 with the center tap M connected. This corresponds to that situation 3 in the second line section A2 , The current curves of 3 can start from the rectifier 14 towards the battery assembly 12 be transferred to this charging process. The second battery module BM2 is bridged and de-energized during this charging process. The second diode D2 prevents a short-circuit discharge current of the second battery module BM2 , The first switching element S1 is open in this third charging, that is, the first inductance L1 is integrated in the path of the power transmission. The second switching element S2 is operated clocking, so consisting of the first inductance L1 , the second switching element S2 and the first diode D1 a boost converter is shown. This boost converter forms together with the rectifier 14 a PFC circuit. This PFC circuit can be used to charge the second battery module. During charging, the potentials of the battery assembly 12 of high voltage plus and high voltage minus related to the neutral conductor N always at a constant value. Thus, a leakage current over the Y Capacities are avoided, which would cause a residual current circuit breaker to trip. In this charging process, the second battery module BM2 not loaded.

Another fourth charge occurs when the neutral conductor N is arranged at the upper terminal of the AC voltage source and a negative half-wave is present. Due to the rectifier 14 correspond to the current flows between the rectifier 14 and the two coils of those of the other charging operations. However, different potentials result in the respective line sections. So lies in this case in the first line section A1 between the rectifier 14 and the first coil L1 the potential 0 Volts while starting from the negative terminal of the rectifier 14 in the direction of the second coil L2 a voltage level between 0 volts and the negative peak voltage is applied. In this fourth charging process, the first switching element S1 and the second switching element S2 closed. Thus, the negative output of the rectifier 14 with the center tap M connected. The first battery module BM1 is bridged and thus without power. The first diode D1 prevents a short circuit discharge current from the first battery circuit B1 , The third switching element is open, which means that the second inductance L2 is integrated in the path of power transmission. Thus, the second line section A2 integrated into the path of power transmission. The fourth switching element S4 is operated clocking, so that consisting of the second inductance L2 , the fourth switching element S4 and the second diode D2 a boost converter is shown. This boost converter forms together with the rectifier 14 a PFC circuit. This PFC circuit becomes the first battery module BM1 loaded. During this charging process, the potentials of high-voltage plus and high-voltage minus are in the battery arrangement 12 relative to the neutral conductor N always at a constant value. This means that in the battery assembly 12 the potentials of high-voltage plus and high-voltage minus can always have the same constant value. This allows a leakage current over the Y Capacities are avoided, which would bring a fault protection circuit breaker to trip. During this charging process, the first battery module BM1 not loaded.

The circuit arrangement 10 can be integrated in a motor vehicle. If the vehicle is to be charged, it can be connected, for example, to a charging station. The live conductor L can provide the required electrical energy to charge a vehicle battery. The neutral conductor N is connected to ground potential. Also the protective conductor PE is connected to ground potential. The protective conductor PE is connected to the vehicle body to ensure equipotential bonding of the vehicle's high-voltage electronics. As a result, it is possible to prevent electrostatic charging of, for example, metal housings of electronic components. In order to detect insulation faults before starting the charging process, a DC residual current measurement can be performed. This means that a current measurement of the direct current takes place. This fault current measurement can be performed on the one hand in the building services, on the other hand inside the motor vehicle.

The circuit arrangement 10 can be connected to an electrical system with electrical consumers 16 be connected. An integrated insulation monitor in the automotive heavy-duty system can monitor the insulation resistance and Y capacities. If the values thus determined are above a predetermined threshold value, the high-voltage system can be released for the charging process. A further possibility to register an insulation fault before the start of the charging process would be a voltage measurement of the high-voltage potential of the battery arrangement 12 to the protective conductor PE , You could also from the high voltage negative potential to the protective conductor PE measure or measure the voltage between the center tap M and the battery assembly 12 to the protective conductor PE carry out. With the aid of such voltage measurements it is possible to deduce the insulation value of the high-voltage system. If the value determined thereby corresponds to the predefined setpoint values, the high-voltage system or the circuit arrangement can 10 be released for the loading process. During a charging process with alternating current, the insulation monitor in the vehicle is usually deactivated because the building services engineering can influence the measurement result. An insulation fault during charging would lead to a DC fault current. This DC residual current can be detected by a DC residual current measurement in building services or in the Motor vehicle can be detected. If a DC fault current or the insulation fault is detected, the charging process can be aborted accordingly. This is preferably done when the DC fault current exceeds a predetermined threshold.

4 shows by way of example a part of a further circuit arrangement 10 with more than two battery circuits. In the example of 4 Up to eight battery circuits are shown. For clarity, however, not all components are labeled. Between the first battery module BM1 and the eighth battery module BM8, the remaining battery circuits are arranged accordingly. Due to the switching elements can in the example of 4 different current paths are realized. 4 shows two possible current paths SW1 and SW2 , The charging principle illustrated in the preceding paragraphs may also apply to a battery assembly 12 be used with more than two battery circuits. This requires the center tap M by switching the vertical semiconductor switches from a high-voltage potential to the center tap M respectively. Alternatively, they may be in the battery pack 12 additionally further high-voltage semiconductor switches are located, which in 4 are not shown. Due to the in 4 illustrated current paths SW1 and SW2 would be the second and fourth module C2 and C4 Loading.

For batteries with more than two battery modules, the PFC function can be simplified by using the voltage of individual battery modules as the selectable counter voltage level. Thus, depending on a voltage of a respective battery module, cell balancing may be possible. Cell balancing may be, for example, balancing or balancing different voltage levels of the battery modules. Due to the large number of switching elements, which can be operated flexibly or cyclically, individual battery modules can be charged while other battery modules are not charged. For example, a single battery module can be charged or a desired combination of battery modules can be loaded selectively. In particular, those battery modules can thus be loaded specifically, which have a low reverse voltage and thus are almost discharged. The insulation monitoring, as with the circuit arrangement 10 has been described with two battery modules, is identical to the circuit arrangement 10 from 4 ,

The illustrated examples of the circuit arrangement 10 clearly show that this is an effective and flexible charging of a battery assembly 12 can be enabled. Individual battery modules can be loaded specifically. It can be on the battery assembly 12 constant voltage levels are set. This is achieved in particular by the realized PFC circuit. Using the circuitry 10 A boost converter can be realized together with the rectifier 14 can realize the PFC circuit. Due to this flexible circuit arrangement 10 can be dispensed with a galvanic isolation in the on-board charger. This reduces the cost, the weight and increases the efficiency during the charging process. Since usually only one of two battery modules is charged, the components for the PFC functionality need only be designed for half the battery voltage. The high-voltage potentials of the high-voltage battery (battery arrangement 12 ) and the connected high-voltage system are constant with respect to the vehicle body during the charging process. The Y capacities of the high-voltage on-board electrical system thus do not cause a leakage current to the protective conductor PE , which would blind the FI circuit breaker in the building services. An insulation fault in the high-voltage system of the motor vehicle can be determined by appropriate voltage measurements or by the use of insulation monitors of the battery. Insulation faults during charging can be detected by a DC fault current measurement. In this case, the charging process can be aborted. Thus, there is no double isolation requirement of the high-voltage system in the motor vehicle. Furthermore, it is not necessary to feed in a current for compensating the leakage current. The circuit arrangement 10 can cover all country variants and network forms. One condition, however, is that the peak voltage of the power grid is less than half the minimum battery voltage.

LIST OF REFERENCE NUMBERS

10

circuitry

12

battery assembly

14

rectifier

16

consumer

18

suppression capacitor

N1 - N4

first to fourth connection

L

live conductor

N

neutral

PE

protective conductor

S1 - S4

first to fourth switching element

A1

first line section

A2

second line section

M

center tap

B1

first battery circuit

B2

second battery circuit

BM1

first battery module

BM2

second battery module

Cy +

positive Y capacity

Cy

negative Y capacity

R1 to R5

first to fifth resistance

D1

first diode

D2

second diode

SVD

Current flow reactor current build-up

SVF

Current course freewheeling phase

B8

eighth battery circuit

SW1

first power path

SW2

second power path

SS

current sensor

L1

first inductance

L2

second inductance

C1, C2

first, second module

SM

Sensor for voltage measurement

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

• US 2013/0094255 A1 [0005]
• DE 102011077701 A1 [0006]

Claims (5)

Circuit arrangement (10) for charging a battery arrangement (12) with a plurality of battery modules (B1, B2) a rectifier (14) for transforming an alternating current into a direct current, a first line section (A1) which is connected to the rectifier (14) in series with a first output of the rectifier (14), the first line section (A1) having a first inductance (L1), a first switching element (S1) parallel thereto and a first The first inductance (L1) can be bridged by means of the first switching element (S1) and the first battery circuit (B1) has a first parallel circuit, which in a first branch has a second switching element (FIG. S2) and in a second branch parallel thereto a first battery module (BM1), a second line section (A2) which is connected to the rectifier (14) in series at a second output of the rectifier (14), the second line section (A2) having a second inductance (L2), a third switching element (S3) parallel thereto and a second second battery circuit (B2) to these parallel components, wherein the second inductance (L2) can be bridged with the aid of the third switching element (S3) and the second battery circuit (B2) has a second parallel circuit which has a fourth switching element (S4) in a third branch and has a second battery module (BM2) in a fourth branch, a center tap (M) disposed between the first battery module (BM1) and the second battery module (BM2) and connected to the first branch of the first parallel circuit and / or to the third branch of the second parallel circuit, and - A control unit which is configured, in response to a polarity of the alternating current, the first and the second or the third and fourth switching element for each charging of one of the two battery modules (BM1, BM2) through. Circuit arrangement (10) according to Claim 1 wherein the rectifier (14) is connected to a voltage source having a live conductor (L), a neutral conductor (N) and a protective conductor (PE). The circuit arrangement according to claim 1, wherein the second branch of the first battery circuit has a first diode and the fourth branch of the second battery circuit has a second diode to discharge the battery modules to prevent. Circuit arrangement (10) according to one of Claims 2 to 3 with a connected electrical load (16) and a suppression capacitor (18) which is connected to the protective conductor (PE). Method for charging a battery module in a battery arrangement (12), characterized by : a) determining which terminal of a circuit arrangement (10) according to one of the Claims 2 to 4 current carrying and which connection is designed as neutral conductor (N), by means of a voltage measurement between the protective conductor (PE) and one of the two terminals of the circuit arrangement (10), or determining which terminal of the circuit arrangement (10) according to one of Claims 2 to 4 current-carrying and which connection is designed as neutral conductor (N), by means of a voltage measurement between the center tap (M) and one of the two terminals of the circuit arrangement (10) b) driving the first, second, third and fourth switching element (S1, S2, S3, S4) of the circuit arrangement (10) such that one of the battery modules of the battery arrangement (12) is charged while at the same time another battery module of the battery arrangement is not being charged, the second switching element (S2) and the fourth switching element (S4) being operated in a clocking manner, in order to realize a predetermined potential difference via one battery circuit each.

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