Circuit for pre-charging and discharging intermediate circuit capacitors

Abstract

Circuit (1) for precharging and discharging intermediate circuit capacitors (C1, C2, C3) comprising a pair of primary terminals (A1+, A1-) consisting of a first primary terminal (A1+) and a second primary terminal (A1-) for connecting the circuit (1) to a primary area (HV1) which has a primary two-terminal (C1) operating as an energy sink and / or energy source, in particular designed as an intermediate circuit capacitor, at least one pair of secondary terminals (A2+, A2-, A3+, A3-) each consisting of a first secondary terminal (A2+, A3+) and a second secondary terminal (A2-, A3-) for contacting the circuit (1) with each secondary area (HV2, HV3), each of which has an intermediate circuit capacitance as a secondary two-terminal (C2, C3), a current limiting module (R) which is designed to regulate the current flowing during charging and discharging, a discharge switch (S1, S1.1, S1.2, S1.3) for controlling the discharge of the two-terminal devices (C1, C2, C3), a charging switch (S2) to control the charging of the two-terminal devices (C1, C2, C3), which are interconnected in such a way that both the charging current flowing during charging and the discharging current flowing during discharging are limited by the current limiting module (R), the discharge of the two-terminal devices (C1, C2, C3) of the primary area (HV1) and of at least one secondary area (HV2, HV3) can be controlled by means of the discharge switch (S1, S1.1, S1.2, S1.3) and The charging of the intermediate circuit capacities (C2, C3) of at least one secondary section (HV2, HV3) can be controlled by means of the charging switch (S2).

Description

[0001] The invention relates to a circuit for precharging and discharging intermediate circuit capacitors.

[0002] Numerous circuits for pre-charging and discharging DC link capacitors are known from the prior art, particularly for use in electric vehicles. Pre-charging, in this context, refers to charging the capacitors completely to a predetermined target voltage. These circuits are typically used to ensure the safety, functionality, and longevity of the electrical components when switching on or off the high-voltage system. Separate switching paths are often employed for this purpose: one for the controlled pre-charging of the DC link capacitors immediately after connecting the battery or when the vehicle electrical system is switched on, and another for the targeted discharging of the capacitors, especially during emergency shutdowns, maintenance work, or before switching on sensitive electrical loads.

[0003] In the current state of the art, discrete resistors are typically used as pre-charge resistors, along with various circuit combinations including relays, power semiconductors (such as MOSFETs), contactors, and protection diodes to implement the respective pre-charge and discharge functions. Control and monitoring circuits are also integrated to ensure, for example, voltage adjustment, the avoidance of inrush currents, and a controlled and safe charging and discharging process.

[0004] Various designs are specifically aimed at reducing system complexity, minimizing space requirements in the vehicle, and avoiding efficiency losses. Nevertheless, current technology often still requires separate dimensioning and individual protection of charging and discharging circuits, which, particularly in the context of complex high-voltage systems in modern electric vehicles, leads to greater component complexity and higher integration requirements.

[0005] Such circuits are known, for example, from the disclosures in documents DE 10 2018 221 978 B4, DE 10 2024 204 908 A1 and CN 223567525 U.

[0006] The invention is therefore based on the objective of overcoming the aforementioned disadvantages and providing a circuit that is as reliable as possible and has low complexity, through which DC link capacitances can be optimized to be at least partially charged or pre-charged as well as at least partially discharged or pre-discharged.

[0007] This problem is solved by the combination of features according to claim 1.

[0008] According to the invention, a circuit for pre-charging and discharging two-terminal devices or DC link capacitors that can be connected to the circuit is proposed, which is preferably suitable for both high-voltage and low-voltage applications. When preferably used in vehicles in general, and electric vehicles in particular, the circuit proposed according to the invention is thus usable for their vehicle electrical system and, in particular, for both a high-voltage electrical system present in the vehicle and for a low-voltage electrical system that may also be present. Alternatively, the circuit according to the invention can also be referred to as a pre-charging and discharging circuit for pre-charging and discharging DC link capacitors.

[0009] For clarification, the pre-charging and discharging of the DC link capacitances in this case should also be understood as partial charging and discharging, since it is not necessarily the case that all DC link capacitances have to be charged to the same voltage or completely discharged.

[0010] The circuit proposed according to the invention has a pair of primary terminals and preferably exactly one pair of primary terminals, consisting of a first primary terminal and a second primary terminal, via which the circuit can be contacted with a primary area.

[0011] The primary section features a primary two-terminal device that acts as an energy sink and / or energy source, which is typically an intermediate circuit capacitor. Alternatively, a battery, accumulator, or power grid can also be used as the primary two-terminal device.

[0012] For clarification, the primary area and the two-terminal section of the primary area are not part of the circuit proposed according to the invention, wherein the circuit can also be connected to a battery or accumulator or directly to a power grid via the pair of primary terminals, particularly when used in a motor vehicle, as explained.

[0013] Furthermore, the circuit comprises at least one pair of secondary terminals, each pair consisting of a first secondary terminal and a second secondary terminal, each designed to connect the circuit to a secondary area, each of which has an intermediate circuit capacitance as a secondary two-terminal network.

[0014] Since the secondary sections each have a DC link capacity, these sections can also be referred to as DC link sections. If the primary section also has a DC link capacity, so that it too can be called a DC link section, then the primary section can be referred to as the primary DC link section and the secondary sections as the secondary DC link sections.

[0015] Consequently, according to the invention, connections (a pair of primary connections and at least a pair of secondary connections) are provided via which at least two areas, and thus the two-terminal devices located in these areas, can be connected to the circuit. The areas and the two-terminal devices contained therein are not themselves part of the circuit. Wherever reference is made to the areas and the two-terminal devices in the following, these are always to be understood as the areas and two-terminal devices that can be connected to or made contactable with the corresponding connections of the circuit.

[0016] The connections, or more specifically the primary and secondary connections, serve to define a system boundary and are to be interpreted broadly. For example, fixed wiring or a fixed cable routing without connection contacts can therefore also be understood as a connection within the meaning of the invention.

[0017] Furthermore, according to the invention and essential to the invention, the circuit comprises a current-limiting module, in particular exactly one, configured to regulate the current flowing during charging and discharging. The current-limiting module can be a single resistor, a plurality of resistors connected in series and / or parallel, or a resistor network. The current-limiting module can also be formed by an inductor, semiconductor switches, or other components for current limiting, or it can include these, for example, in addition to a resistor. With regard to the semiconductor switch, the current limiting by means of the current-limiting module could be implemented, for example, by its operation in a linear operating mode or its clocked operation.In this context, adjusting the flowing current within the current limiting module means that the current can be predetermined and limited during the discharge and charging of at least one two-terminal device via the current limiting module.

[0018] To control the circuit, the circuit according to the invention includes a discharge switch for controlling the discharge of the two-terminal devices and a charge switch for controlling the pre-charging or charging of the two-terminal devices. Since, depending on the specific embodiment, exactly one discharge switch or several discharge switches may be provided, the circuit preferably includes at least one discharge switch. However, with regard to the charge switch, preferably exactly one charge switch is always provided.

[0019] The control via the switches (discharge switch and charge switch) is preferably to be understood as "on" and "off", so that the discharging via the (at least one) discharge switch and the charging via the (exactly one) charge switch can each be controlled and switched on and off.

[0020] For both the (preferably at least one) discharge switch and the (preferably exactly one) charge switch, in addition to classic electromechanical relays, contactors, semiconductor switches or the like can also be used.

[0021] The switches can be configured to control charging and discharging by being switched on or off "hard" once for each control process. Alternatively, they can be controlled in pulsed mode (and thus multiple times) during each control process, for example, using pulse-width modulation, and thus operated in a pulsed mode. When using semiconductor switches, the control of charging and discharging can also be implemented through linear operation of the semiconductor switches.

[0022] However, it is essential to the invention that the circuit is constructed and the aforementioned components are interconnected in such a way that both a charging current flowing when charging an intermediate circuit capacitance - in particular each secondary region - and a discharge current flowing when discharging a two-terminal network - in particular both the primary region and each secondary region - are limited by the current limiting module, so that the circuit preferably requires exactly one current limiting module.

[0023] Furthermore, the discharge of the two-poles of the primary area and of at least one secondary area by means of the discharge switch and the charging of the two-poles of the at least one secondary area by means of the charging switch can be controlled, whereby, if necessary and depending on the embodiment, the area switches mentioned below also participate in the control.

[0024] The core idea of ​​the circuit is that pre-charge paths for charging and discharge paths for discharging the two-terminal devices are combined in such a way that, on the one hand, several areas can be charged or discharged, and on the other hand, otherwise separate pre-charge and discharge resistors are replaced by the current limiting module, so that all discharge and pre-charge paths are identical section by section and run through the current limiting module.

[0025] This allows for multiple pre-charging or discharging areas, or a cascade of these areas (each of which can be pre-charged and discharged), through a common load formed by the current limiting module.

[0026] This also allows for the gradual or simultaneous preloading of different areas.

[0027] Because the circuit preferably has two or more independent pre-charge paths (except for the current limiting module), in the event of a defect in one area, the other areas can remain fully functional and continue to be pre-charged. The same applies analogously to the discharge paths, so that in the event of a defect in one area, the other areas remain fully functional and can continue to be discharged.

[0028] According to a further development, it can be provided that a first discharge path is provided for the two-terminal primary section, leading from the first primary terminal to the second primary terminal and, in particular, running in series through the discharge switch and the current limiting module. In this way, the discharge of the two-terminal primary section can be controlled by the discharge switch, and the discharge current flowing through the current limiting module is adjustable.

[0029] Furthermore, each pair of secondary terminals can be provided with an additional discharge path for the DC link capacitance of the respective secondary section. This path leads from the first secondary terminal to the second secondary terminal and, in particular, runs in series through the discharge switch and the current limiting module. This allows the discharge of the respective DC link capacitance of the respective secondary section to be controlled by the respective section switches and the discharge switch, and the discharge current flowing through the current limiting module is adjustable.

[0030] Furthermore, each pair of secondary terminals can have a charging path for the DC link capacitance of the respective secondary section, leading from the first primary terminal to the respective first secondary terminal and from the respective second secondary terminal to the second primary terminal, and in particular running in series through the charging switch and the current limiting module. This allows the charging of the respective DC link capacitance of the respective secondary section to be controlled by the charging switch, and the charging current flowing through the current limiting module is adjustable.

[0031] This design of the discharge and charge paths ensures that clearly defined current paths exist for both the primary and secondary circuits, through which all charging and discharging processes are routed. The series connection of circuit switches, a current limiting module, a discharge switch, and a charge switch allows for the targeted, selective activation of individual circuits or their two-terminal or DC link capacitances without creating uncontrolled current paths. The adjustable current limit via the current limiting module reduces component stress and enables reproducible, gentle pre-charging of the secondary DC link capacitances as well as controlled discharge, which particularly benefits safety, component lifespan, and standardized operation.

[0032] In order to be able to switch the secondary circuits provided at the secondary terminals on and off independently of one another, and thus also – if necessary – to control the charging and discharging of their intermediate circuit capacitances separately, a first circuit switch connected in series with each first secondary terminal is provided according to the invention, by means of which the respective first secondary terminal can be electrically connected to the first primary terminal. Similarly, a second circuit switch connected in series with each second secondary terminal is provided, by means of which the respective second secondary terminal can be electrically connected to the second primary terminal.

[0033] These range switches, formed for example by contactors, do not have to be an integral part of the actual circuit for pre-charging and discharging two-poles or DC link capacitors and can also be located, for example, in a separate system or a separate assembly, and in particular in the areas where the circuit or a control unit mentioned below can have control connections for controlling such range switches.

[0034] If range switches are provided, they are connected to the current limiting module, the discharge switch and the charge switch in such a way that both the charging current and the discharge current flowing during charging are still limited by the current limiting module, but the discharge of the two-terminal devices or the DC link capacitances of the primary area and at least one secondary area can be controlled jointly by means of the discharge switch and the range switches, and the charging of the two-terminal devices or the DC link capacitances of at least one secondary area can be controlled jointly by means of the charge switch and the range switches.

[0035] The area switches allow the secondary areas to be selectively switched on and off for charging or discharging, so that they can be charged and discharged separately.

[0036] Although not strictly necessary for the primary area, range switches can also be provided for the primary area, whereby a first range switch, by which the respective first primary connection can be disconnected from the circuit, and a second range switch, by which the respective second primary connection can be disconnected from the circuit, can be provided.

[0037] Starting from the described discharge paths and charging paths, and starting from the range switches provided for the secondary sections, it can further be provided that the additional discharge path for the DC link capacitance of the respective secondary section, provided for each pair of secondary connections, leads via the respective first range switch and the respective second range switch, between which, in particular, the discharge switch and the current limiting module are arranged in series, so that the discharge of the respective DC link capacitance of the respective secondary section can be controlled jointly by the respective range switches and the discharge switch. Apart from the fact that the discharge switch must be activated for discharge, it is preferably provided that both the respective first range switch and the respective second range switch are closed.

[0038] Starting again from the described discharge paths and charging paths, as well as from the range switches provided for the secondary sections, it can also be provided that the charging path for the DC link capacitance of each secondary section, provided for each pair of secondary connections, leads via the respective first range switch, to which the charging switch and the current limiting module are connected, in particular in series, so that the charging of the respective DC link capacitance of the respective secondary section can be jointly controlled by the respective first range switch and the charging switch. Apart from the fact that the charging switch must be activated for charging, it is preferably provided that the respective first range switch is closed and the respective second range switch is open.

[0039] Assuming the presence of range switches for the secondary ranges, it should also be noted that if only the two-pole or the DC link capacitance of the primary range is to be discharged, these switches are open.

[0040] In a further embodiment, the circuit can be provided with at least two pairs of secondary connections. This allows the circuit to be connected via a first pair of secondary connections to a first secondary section, which has an intermediate circuit capacitance, and via a second pair of secondary connections to a second secondary section, which also has an intermediate circuit capacitance.

[0041] Accordingly, this advanced circuit enables the operation of multiple, separate secondary circuits, each with its own DC link capacity, using a single circuit. This allows for the targeted pre-charging and discharging of multiple sub-drives, subnetworks, or modular power units from a common primary circuit. This results in advantages regarding the modularity and scalability of the system, as well as a reduction in hardware complexity, since multiple secondary circuits can be managed via a shared current limiting and switching infrastructure.

[0042] Although generally foreseeable, in such an embodiment having several pairs of secondary connections it is particularly advantageous if, in addition, at least one first reverse current blocking element is provided downstream of the respective second secondary connection between the respective connection and the charging switch, by which a reverse current to the respective second secondary connection is blocked when the charging switch is closed.

[0043] In particular, a diode can be used as such a reverse current blocking element, whereby the function of the reverse current blocking element or the function of a diode can also be implemented by a corresponding control or design of the charging switch, a back-to-back switch (by suitable interconnection of a p-channel and an n-channel MOSFET against each other) or other suitable components.

[0044] The use of the first reverse current blocking element prevents currents from other parts of the circuit from flowing back into the respective second secondary terminal when the charging switch is closed. This reduces unwanted backfeeding into the secondary circuit or connected loads and increases operational reliability. At the same time, uncontrolled charging currents between different DC link capacitances are avoided, which improves the electrical decoupling of the individual sections and simplifies the design of further protective measures.

[0045] According to a further advantageous embodiment, at least one second reverse current blocking element can be provided downstream of both the first primary terminal and each first secondary terminal, by which a reverse current to the respective terminal (first primary terminal or first secondary terminal) is blocked when the discharge switch is closed. If, in particular, range switches are provided for the first secondary terminals, the respective discharge path can lead from the respective first secondary terminal via the respective second reverse current blocking element in parallel to the respective first range switch to the discharge switch.

[0046] A first particularly advantageous embodiment of the circuit provides that it has exactly one discharge switch, which is designed and arranged in the circuit to control the discharge of all connectable two-terminal networks or DC link capacitors. The circuit is designed such that—if range switches are provided—when a DC link capacitor is discharged by means of the respective range switches, at least one of the secondary networks always discharges the two-terminal network or DC link capacitor of the primary network simultaneously.

[0047] The technical advantage of this design lies in the particularly simple and cost-effective implementation of the discharge function using a single discharge switch for all two-terminal components or, if applicable, for all DC link capacitances. By coupling the discharge of a secondary circuit with the simultaneous discharge of the primary circuit, potential differences between the primary and secondary circuits are reduced or eliminated. This reduces insulation stress and can simplify the safety concept, especially during maintenance or emergency shutdowns, since a discharge process always brings the primary circuit to a safe voltage level.

[0048] According to a particularly advantageous second embodiment, which is an alternative to the first embodiment, the circuit is provided to have one discharge switch for each pair of primary terminals and one for each pair of secondary terminals, and thus one discharge switch for each section. These discharge switches are designed and arranged in the circuit to control the discharge of the respective connectable two-terminal device of the respective connectable section, so that when a DC link capacitance of one of the secondary sections is discharged, the discharge of the two-terminal device or, if applicable, the DC link capacitance of the primary section can be controlled independently.

[0049] This design, with a dedicated discharge switch for each pair of primary and secondary connections, achieves a high degree of selectivity in the discharge processes. Specifically, it allows for a decision on whether and when the primary section is discharged independently of the secondary sections. This enables, for example, secondary sections to be discharged and shut down or serviced while the primary section continues to operate, or vice versa. The result is increased operational flexibility, tailored safety concepts, and the ability to independently bring different subnetworks into a safe state.

[0050] An alternative, and equally advantageous, third development, which essentially corresponds to a hybrid of the first and second developments, provides that the circuit has a first discharge switch, designed and arranged in the circuit to control the discharge of at least one connectable two-terminal device, and that the circuit has a second discharge switch, designed and arranged in the circuit to control the discharge of at least two other connectable two-terminal devices.

[0051] The technical effect of this design is that, by dividing the system into a first discharge switch for at least one connectable two-terminal network or DC link capacitance and a second discharge switch for at least two other connectable two-terminal networks or DC link capacitances, different groups of two-terminal networks or DC link capacitances can be discharged separately. This allows for more flexible operation, such as prioritizing or accelerating the discharge of certain areas while controlling other areas independently.

[0052] This can be particularly advantageous when two-terminal networks or intermediate circuit capacities are subject to different voltage levels, safety requirements, or discharge times.

[0053] In addition, at least one third reverse current blocking element can be provided upstream of each second secondary connection, by which a reverse current not flowing via the current limiting module from the respective second secondary connection to the second primary connection is blocked.

[0054] If, in particular, area switches are provided for the second secondary terminals, the respective discharge path from the discharge switch to the respective second secondary terminal can lead via the respective third backflow prevention element in parallel to the respective second area switch.

[0055] Furthermore, the circuit can include a control unit designed to control the charging and discharging of the intermediate circuit sections connectable to the pair of primary terminals and each pair of secondary terminals. This control unit is connected, or connectable, to the discharge switch and / or the charge switch and / or at least some of the section switches, or preferably to all section switches.

[0056] The control unit allows for the coordinated control and operation of various switches, such as discharge switches, charge switches, and range switches. This enables complex operating strategies, such as sequential or parallel pre-charging of multiple secondary DC link ranges, defined discharge sequences in case of faults or maintenance, and current adjustment via the current limiting module to different operating conditions. The result is automated, reproducible operation, improved diagnostic capabilities, and overall increased operational reliability and efficiency of the system.

[0057] Regarding the control unit, it should also be noted that it is preferably designed to control the discharge switch and the charge switch, as well as any range switches that may be present – ​​insofar as these are necessary for charging or discharging – in such a way that exactly one or at least one intermediate circuit capacity of a secondary range is charged during a charging process and exactly one or at least one two-pole of the primary range and / or a secondary range is discharged during a discharging process.

[0058] The features disclosed above can be combined in any way, provided that this is technically possible and they do not contradict each other.

[0059] Other advantageous embodiments of the invention are characterized in the dependent claims or are described in more detail below together with the description of the preferred embodiment of the invention with reference to the figures. The figures show: Fig. 1 a first variant of a circuit for three or more intermediate circuit sections; Fig. 2 a control unit of a circuit according to Fig. 1; Fig. 3 a second variant of a circuit for two intermediate circuit sections; Fig. 4 a third variant of a circuit for two intermediate circuit sections; Fig. 5. Pre-charging an intermediate circuit capacitor using the circuit from Fig. 4; Fig. 6. Discharging an intermediate circuit capacitor using the circuit from Fig. 4; Fig. 7. Discharging two intermediate circuit capacitors using the circuit from Fig. 4; Fig. 8 a fourth variant of a circuit for three or more intermediate circuit sections; Fig. 9. Pre-charging an intermediate circuit capacitor using the circuit from Fig. 8; Fig. 10. Discharging an intermediate circuit capacitor using the circuit from Fig. 8; Fig. 11 a fifth variant of a circuit for three or more intermediate circuit sections; Fig. 12. Discharging an intermediate circuit capacitor using the circuit from Fig. 11.

[0060] The figures are schematic examples. Identical reference symbols in the figures indicate identical functional and / or structural features. Furthermore, it should be clarified that the figures are schematic electrical circuit diagrams and that the invention is not limited to the specific circuit configuration shown.

[0061] Regarding all embodiments illustrated by the figures, it should be noted that both the primary area HV1 and the secondary areas HV2, HV3 are intermediate circuit areas HV1, HV2, HV3, and, by way of example, not only the secondary two-terminal networks C2, C3 are intermediate circuit capacities C2, C3, but also the primary two-terminal network C1 is an intermediate circuit capacity C1, wherein the primary two-terminal network C1 can alternatively also be a battery, an accumulator or a power grid. Furthermore, it should be clarified that the intermediate circuit sections HV1, HV2, HV3 as well as their intermediate circuit capacitances C1, C2, C3 are not part of the actual circuit 1 for pre-charging and discharging the intermediate circuit capacitances C1, C2, C3 represented as capacitors, but are to be understood as being continuously connectable to circuit 1 and in particular as being contactable with circuit 1 via the terminals A1+, A1-, A2+, A2-, A3+, A3- of circuit 1.

[0062] Regarding the intermediate circuit capacitances C1, C2, C3, a voltage or reference potential difference is applied across each of them, which is designated V1 for the intermediate circuit capacitance C1 of the primary intermediate circuit area HV1, V2 for the intermediate circuit capacitance C2 of the (first) secondary intermediate circuit area HV2, and, if present, V3 for the intermediate circuit capacitance C3 of the (further or second) secondary intermediate circuit area HV3, and can also be, for example, 0 volts as a result of a possible discharge.

[0063] Insofar as the secondary connections A2+, A2-, A3+, A3- of the secondary intermediate circuit sections HV2, HV3 are provided with range switches K2+, K2-, K3+, K3-, these can be understood as part of circuit 1, whereby they can also be part of another circuit and can only optionally be controlled by circuit 1 or its control unit 2, as is exemplified in Fig. 2 is shown.

[0064] In Fig. Figure 1 shows a first variant of the circuit 1 according to the invention, which is suitable for three or more intermediate circuit areas HV1, HV2, HV3 or three or more intermediate circuit capacitances C1, C2, C3 each determining an intermediate circuit area HV1, HV2, HV3, wherein only two secondary intermediate circuit areas HV2, HV3 are shown by way of example, although further secondary intermediate circuit areas may be provided.

[0065] This has independent pre-charging paths with regard to the intermediate circuit capacities C2, C3 of the secondary intermediate circuit areas HV2, HV3, so that the intermediate circuit capacities C2, C3 of the secondary intermediate circuit areas HV2, HV3 can be charged or pre-charged independently of each other or simultaneously from the primary intermediate circuit area HV1 or from its intermediate circuit capacity C1.

[0066] The discharge paths of the DC link capacitors C2 and C3 of the secondary DC link sections HV2 and HV3 are not independent of each other, as they can only be discharged independently when the section switches are appropriately controlled. Furthermore, they can only be discharged together with the primary DC link section HV1 or its DC link capacitor C1, or their respective voltages V2 and V3 can only be reduced to the voltage V1 of the DC link capacitor C1 of the primary DC link section HV1.

[0067] In order to charge and discharge the DC link capacities C2, C3 of the secondary DC link areas HV2, HV3, the area switches K2+, K2-, K3+, K3- must also be in a corresponding switching state or, for example, be switched into this state by the control unit 2.

[0068] For pre-loading and unloading according to Fig. In the circuit 1, which has three intermediate circuit sections HV1, HV2, HV3, a pair of primary connections A1+, A1- consisting of a first primary connection A1+ and a second primary connection A1- for connecting the circuit 1 to a primary intermediate circuit section HV1 having an intermediate circuit capacitance C1, and two pairs of secondary connections A2+, A2-, A3+, A3- each consisting of a first secondary connection A2+, A3+ and a second secondary connection A2-, A3- each for connecting the circuit 1 to a secondary intermediate circuit section HV2, HV3 each having an intermediate circuit capacitance C2, C3.

[0069] Furthermore, for the secondary intermediate circuit areas HV2, HV3, area switches K2+, K2-, K3+, K3- designed as contactors are provided and connected upstream of the secondary terminals in such a way that a direct electrical connection to the primary terminals A1+, A1- acting in parallel to circuit 1 can be interrupted in a controlled manner.

[0070] Furthermore, circuit 1 includes as an essential element a current limiting module R, which is represented by example as a resistor and which is designed to limit the current flowing when charging the DC link capacitances C2, C3 of the secondary DC link areas HV2, HV3 and discharging all DC link capacitances C1, C2, C3 of all DC link areas HV1, HV2, HV3.

[0071] Furthermore, circuit 1 shows according to Fig. 1 exactly one discharge switch S1 for controlling the discharge of the DC link capacities C1, C2, C3 and exactly one charge switch S2 for controlling the charging of the DC link capacities C2, C3, which are interconnected with each other and with the current limiting module R in such a way that charging and discharging can be controlled by the switches S1, S2 and both a charging current flowing during charging and a discharge current flowing during discharging is limited by the current limiting module R.

[0072] To prevent an unwanted reverse current from the second secondary terminal A2- between the second secondary terminals A2-, A3- when charging a single intermediate circuit capacity C2, C3 of one of the secondary intermediate circuit areas HV2, HV3, where the charging switch S2 is closed, a first reverse current blocking element D1, D2, for example designed as a diode, is also provided downstream of each second secondary terminal A2-, A3-, by which a reverse current to the respective second secondary terminal A2-, A3- is prevented when the charging switch S2 is closed.

[0073] Referring once again to Fig. Figure 2 shows an exemplary control unit 2, which is connected to the discharge switch S1 and the charge switch S2 via control technology and is either permanently connected to the range switches K2+, K2-, K3+, K3- or connectable to them via control terminals. The control unit 2 is configured to control the discharge switch S1, the charge switch S2, and, if necessary, the range switches K2+, K2-, K3+, K3- such that, during discharge, one or more of the DC link capacitances C1, C2, C3 are discharged or discharged to the same potential, or, during charging or pre-charging, one or more of the DC link capacitances C2, C3 of the secondary DC link ranges HV2, HV3 are charged from the DC link capacitance C1 of the primary DC link range HV1.

[0074] For clarification, control unit 2 is only in Fig. 2 and for circuit 1 according to Fig. 1 shown, wherein this is also present in all further embodiments of the circuit 1 according to the invention and can be connected to the corresponding discharge switches S1, S1.1, S1.2, S1.3 and the charging switch S2, and - insofar as necessary for controlling the discharging and charging - can be connected or connectable to the necessary range switches K2+, K2-, K3+, K3-.

[0075] In Fig. Figure 3 shows a second, simplified variant of the circuit 1 according to the invention, which is suitable for two intermediate circuit sections HV1, HV2 or two intermediate circuit capacitors C1, C2, each defining one intermediate circuit section HV1, HV2. This variant omits the second secondary connections K3+, K3-, so that all conductor tracks and components necessary for the second secondary intermediate circuit section HV3 are eliminated. Further details regarding Fig. 1. The following apply analogously.

[0076] The in Fig. The third variant shown in Figure 4 corresponds to a further simplified version of the variant according to Figure 4. Fig. 3, so that everything, to Fig. 3 and Fig. 1. The following applies analogously.

[0077] To illustrate the functionality of circuit 1 according to Fig. 4, illustrated Fig. 5. Stepwise, the charging or pre-charging of the DC link capacitance C2 of the secondary DC link section HV2 from the DC link capacitance C1 of the primary DC link section HV1, which is charged in the initial state. For better clarity, the following is omitted. Fig. The four known reference symbols identical to these have been omitted.

[0078] Consequently, the following applies to the charging or pre-charging process, which is controlled in particular by the control unit 2: Fig. 5. The following: Step 1) Initial state in which discharge switch S1, charge switch S2 and the range switches K2+, K2- are open and from which the DC link capacity C2 is to be charged. Step 2) The first area switch K2+ is closed, thereby establishing a direct electrical connection between the first primary terminal A1+ and the first secondary terminal A2+. Step 3) The charging switch S2 is closed, thereby establishing an electrical connection between the second secondary terminal A2- via the current limiting module R and the second primary terminal A1-.

[0079] As shown in the diagram corresponding to step 3). Fig. As shown in Figure 5, this creates or closes a charging path (shown by arrows) for the DC link capacity C2 of the secondary DC link area HV2, so that current can flow from the primary DC link area HV1 into the secondary DC link area HV2 via the current limiting module R and thus be charged according to its DC link capacity C2. Step 4) Once the desired pre-charge state, i.e. the desired potential difference V2 of the DC link capacitance C2 of the secondary DC link area HV2, is reached, the second area switch K2- is closed and thereby a direct electrical connection is established between the second primary terminal A1- and the secondary terminal A2-. Step 5) The charging switch S2 is opened. The pre-charging process is now complete.

[0080] Provided that the technical function is maintained, the steps can also be swapped. In particular, steps 2) and 3) as well as steps 4) and 5) can each be swapped.

[0081] Further illustrated Fig. 6 To illustrate the operation of the circuit, the discharge of only the DC link capacitance C1 of the primary DC link area HV1 is shown step by step. Fig. 7. The discharge of the DC link capacitance C2 of the secondary DC link section HV2 is carried out stepwise, which, due to the interconnection, occurs together with the DC link capacitance C1 of the primary DC link section HV1. It is assumed that the DC link capacitance C1 of the primary DC link section HV1 is at least partially charged in the respective initial state. The same applies to the [unclear - possibly "in the context of the circuit description"]. Fig. The procedure shown in Figure 7 also applies to the intermediate circuit capacity C2 of the secondary intermediate circuit section HV2. Here too, for clarity, reference is made to the diagram. Fig. The four known reference symbols identical to these have been omitted.

[0082] Consequently, the following applies to the unloading controlled in particular by the control unit 2: Fig. 6. The following: Step 1) Initial state in which discharge switch S1, charge switch S2 and the range switches K2+, K2- are open and from which the DC link capacity C1 is to be discharged. Step 2) The discharge switch S1 is closed, thereby establishing an electrical connection between the first primary terminal A1+ via the current limiting module R and the second primary terminal A1-.

[0083] As shown in the diagram corresponding to step 2). Fig. As shown in Figure 6, this creates or closes a discharge path (shown by arrows) for the DC link capacitance C1 of the primary DC link area HV1, so that a current discharging the DC link capacitance C1 can flow through the current limiting module R. Step 3) Once the desired discharge state, i.e., the desired potential difference V1 of the DC link capacitance C1 of the primary DC link section HV1, is reached, the discharge switch S1 is opened. The discharge process is then complete.

[0084] Similarly to Fig. Section 6 applies in particular to unloading controlled by the control unit 2 in accordance with Fig. 7 the following: Step 1) Initial state in which discharge switch S1, charge switch S2 are open and the range switches K2+, K2- are closed, and from which the DC link capacitances C1 and C2 are to be discharged. Step 2) The discharge switch S1 is closed, thereby establishing an electrical connection between the first primary terminal A1+ via the current limiting module R with the second primary terminal A1- and an electrical connection between the first secondary terminal A2+ via the current limiting module R with the second secondary terminal A2-.

[0085] As shown in the diagram corresponding to step 2). Fig. As shown in Figure 7, a discharge path (shown by arrows) is formed or closed for each intermediate circuit capacity C1, C2, so that a current can flow through the current limiting module R, allowing the intermediate circuit capacity C2 to reach the level of the intermediate circuit capacity C1 and both of these to discharge further. Step 3) Once the desired discharge state is reached, i.e., the desired potential difference V2 of the DC link capacitance C2 of the secondary DC link section HV2 or of the DC link capacitance C1 of the primary DC link section HV1, the discharge switch S1 and the two section switches K2+ and K2- are opened. The discharge process is then complete.

[0086] In particular, opening the switches in step 3) does not have to happen simultaneously, but can also be done at different times or in several steps.

[0087] In Fig. Figure 8 shows a fourth variant of the circuit 1 according to the invention, which is essentially the same as the variant according to Fig. 1 is designed and is also suitable for three or more intermediate circuit areas HV1, HV2, HV3 or three or more intermediate circuit capacities C1, C2, C3 each determining an intermediate circuit area HV1, HV2, HV3, whereby only two secondary intermediate circuit areas HV2, HV3 are shown as examples, although further secondary intermediate circuit areas may be provided.

[0088] Circuit 1 according to Fig. Circuit 8 differs from circuit 1 in that... Fig. 1, that not exactly one discharge switch S1, but rather one discharge switch S1.1, S1.2, S1.3 is provided for each intermediate circuit area HV1, HV2, HV3, wherein the respective discharge switch S1.1, S1.2, S1.3 is electrically directly connected to the respective first terminal A1+, A2+, A3+ and thus bridging any existing first area switches K2+, K3+.

[0089] On the other hand, circuit 1 differs according to Fig. 8 of circuit 1 according to Fig. 1, that for each second secondary connection A2-, A3- furthermore a third reverse current blocking element D3, D4 is provided upstream of the respective second secondary connection A2-, A3-, by which a reverse current not flowing via the current limiting module R from the respective second secondary connection A2-, A3- to the second primary connection A1- is blocked.

[0090] To illustrate the functionality of circuit 1 according to Fig. 8, illustrated Fig. 9. Stepwise, the charging or pre-charging of the DC link capacitance C2 of the first secondary DC link section HV2 from the primary DC link section HV1, whereby the DC link capacitance C1 of the primary DC link section HV1 is correspondingly charged in the initial state. For better clarity, reference is made to the Fig. 8 known reference symbols identical to these have been omitted.

[0091] Consequently, the following applies to the charging or pre-charging process, which is controlled in particular by the control unit 2: Fig. 9 the following: Step 1) Initial state in which all discharge switches S1.1, S1.2, S1.3, charging switch S2 and the range switches K2+, K2-, K3+, K3- are open and from which the DC link capacity C2 is to be charged. Step 2) The first range switch K2+ of the first secondary DC circuit range HV2 is closed, thereby establishing a direct electrical connection between the first primary terminal A1+ and the first secondary terminal A2+ of the first secondary DC circuit range HV2. Step 3) The charging switch S2 is closed, thereby establishing an electrical connection between the second secondary terminal A2- via the current limiting module R and the second primary terminal A1-.

[0092] As shown in the diagram corresponding to step 3). Fig. As shown in Figure 9, this creates or closes a charging path (shown by arrows) for the DC link capacity C2 of the secondary DC link area HV2, so that current can flow from the primary DC link area HV1 into the secondary DC link area HV2 via the current limiting module R and thus be charged according to its DC link capacity C2. Step 4) Once the desired pre-charge state, i.e. the desired potential difference V2 of the DC link capacitance C2 of the first secondary DC link area HV2, is reached, the second area switch K2- is closed and thereby a direct electrical connection is established between the second primary terminal A1- and the secondary terminal A2-. Step 5) The charging switch S2 is opened. The pre-charging process is now complete.

[0093] Provided that the technical function is maintained, the steps can also be swapped. In particular, steps 2) and 3) as well as steps 4) and 5) can each be swapped.

[0094] Further illustrated Fig. 10 to illustrate the functionality of circuit 1 according to Fig. 8. Stepwise, the discharge of only the intermediate circuit capacitance C2 of the first secondary intermediate circuit section HV2, which is achieved with the circuit according to Fig. 1 was not possible. Here too, for better clarity, reference is made to the following: Fig. The four known reference symbols identical to these have been omitted.

[0095] Consequently, the following applies to the unloading controlled in particular by the control unit 2: Fig. 10 the following: Step 1) Initial state in which all discharge switches S1.1, S1.2, S1.3, charging switch S2 and all range switches K2+, K2-, K3+, K3- are open and from which the DC link capacity C2 is to be discharged. Step 2) The discharge switch S1.2, which is assigned to the first secondary DC link area HV2 or its DC link capacity C2, is closed, thereby establishing an electrical connection between the first secondary terminal A2+ via the current limiting module R and the second secondary terminal A2-.

[0096] As shown in the diagram corresponding to step 3). Fig. As shown in Figure 10, this creates or closes a discharge path (shown by arrows) for the DC link capacitance C2 of the first secondary DC link area HV2, so that a current discharging the DC link capacitance C2 can flow through the current limiting module R.

[0097] Once the desired discharge state, i.e., the desired potential difference V2 of the DC link capacitance C2 of the first secondary DC link section HV2 (in this case 0 volts), is reached, no current flows, as shown in the diagram corresponding to step 4). Fig. 10 is shown. Step 5) Once the desired discharge state, i.e., the desired potential difference V2 of the DC link capacitance C2 of the first secondary DC link section HV2, is reached, the corresponding, previously closed discharge switch S1.2 is opened. The discharge process is then complete.

[0098] Steps 3) and 4) according to Fig. The 10 steps shown here serve only as illustrative intermediate steps and do not represent actual changes in the state of the switches.

[0099] In Fig. Figure 11 shows a fifth variant of the circuit 1 according to the invention, which is essentially the same as the variant according to Figure 11. Fig. 1 is designed and is also suitable for three or more intermediate circuit areas HV1, HV2, HV3 or three or more intermediate circuit capacities C1, C2, C3 each determining an intermediate circuit area HV1, HV2, HV3, whereby only two secondary intermediate circuit areas HV2, HV3 are shown as examples, although further secondary intermediate circuit areas may be provided.

[0100] Circuit 1 according to Fig. Circuit 11 differs from circuit 1 in that... Fig. 1, that although exactly one discharge switch S1 is provided, a second reverse current blocking element D5, D6, D7 is connected upstream of the discharge switch S1 for each intermediate circuit area HV1, HV2, HV3, so that the first terminals A1+, A2+, A3+ assigned to the intermediate circuit areas HV1, HV2, HV3 are electrically directly connected and the intended first area switches K2+, K3+ are bridged with the exactly one discharge switch S1, but this is not connected in the reverse direction to the first terminals A1+, A2+, A3+.

[0101] On the other hand, circuit 1 differs according to Fig. 11 of circuit 1 according to Fig. 1 analogous to circuit 1 according to Fig. 8 in that a third reverse current blocking element D3, D4 is provided upstream of each second secondary connection A2-, A3-, by which a reverse current not flowing via the current limiting module R from the respective second secondary connection A2-, A3- to the second primary connection A1- is blocked.

[0102] Fig. Figure 12 illustrates the operation of circuit 1 according to Fig. 11. Stepwise discharge of all intermediate circuit capacities C1, C2, C3, since these cannot be discharged independently of each other. Advantageous compared to the embodiment as described, for example, by Fig. However, as illustrated in Figure 1, the area switches K2+, K2-, K3+, K3- do not need to be closed for discharge.

[0103] Consequently, the following applies to the unloading controlled in particular by the control unit 2: Fig. 11 the following: Step 1) Initial state in which discharge switch S1, charge switch S2 and all range switches K2+, K2-, K3+, K3- are open and from which the DC link capacitances C1, C2, C3 are to be discharged. Step 2) The discharge switch S1 is closed, thereby establishing an electrical connection between the first primary terminal A1+ via the current limiting module R with the second primary terminal A1-, an electrical connection between the first secondary terminal A2+ with the second secondary terminal A2- of the first secondary DC link area HV2 via the current limiting module R, and an electrical connection between the first secondary terminal A3+ with the second secondary terminal A3- of the second secondary DC link area HV3 via the current limiting module R.

[0104] As shown in the diagram corresponding to step 3). Fig. As shown in Figure 12, this creates or closes a discharge path for each intermediate circuit capacity C1, C2, C3, i.e., three discharge paths in this case (shown by arrows), so that a current discharging the respective intermediate circuit capacity C1, C2, C3 can flow through the current limiting module R.

[0105] Once the desired discharge state is reached, i.e., the desired potential difference V1, V2, V3 of the intermediate circuit capacitances C1, C2, C3 (in this case 0 volts), no current flows, as shown in the diagram corresponding to step 4). Fig. 12 is shown. Step 5) Once the desired discharge states, i.e., the desired potential differences V1, V2, V3 of the DC link capacitances C1, C2, C3, have been reached, the discharge switch S1 is opened. The discharge process is then complete.

[0106] Steps 3) and 4) according to Fig. The 12 steps shown here serve only as illustrative intermediate steps and do not represent actual changes in the state of the switches.

[0107] Precharging of the intermediate circuit capacities C2, C3 of the secondary intermediate circuit areas HV2, HV3 takes place with regard to the in Fig. The variant shown in 11 is analogous to those in Fig. 8 and Fig. 9 illustrated variants. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2018 221 978 B4

[0005] DE 10 2024 204 908 A1

[0005] CN 223567525 U

[0005]

Claims

[1] Circuit (1) for precharging and discharging intermediate circuit capacitors (C1, C2, C3) comprising a pair of primary terminals (A1+, A1-) consisting of a first primary terminal (A1+) and a second primary terminal (A1-) for connecting the circuit (1) to a primary area (HV1) which has a primary two-terminal (C1) operating as an energy sink and / or energy source, in particular designed as an intermediate circuit capacitor, at least one pair of secondary terminals (A2+, A2-, A3+, A3-) each consisting of a first secondary terminal (A2+, A3+) and a second secondary terminal (A2-, A3-) for contacting the circuit (1) with each secondary area (HV2, HV3), each of which has an intermediate circuit capacitance as a secondary two-terminal (C2, C3), a current limiting module (R) which is designed to regulate the current flowing during charging and discharging, a discharge switch (S1, S1.1, S1.2, S1.3) for controlling the discharge of the two-terminal devices (C1, C2, C3), a charging switch (S2) to control the charging of the two-terminal devices (C1, C2, C3), which are interconnected in such a way that both the charging current flowing during charging and the discharging current flowing during discharging are limited by the current limiting module (R), the discharge of the two-terminal devices (C1, C2, C3) of the primary area (HV1) and of at least one secondary area (HV2, HV3) can be controlled by means of the discharge switch (S1, S1.1, S1.2, S1.3) and The charging of the intermediate circuit capacities (C2, C3) of at least one secondary section (HV2, HV3) can be controlled by means of the charging switch (S2). [2] Circuit according to claim 1, wherein a first discharge path is provided for the two-terminal (C1) of the primary area (HV1), which leads from the first primary terminal (A1+) to the second primary terminal (A1-) and thereby via the discharge switch (S1) and the current limiting module (R), so that the discharge of the two-terminal (C1) of the primary area (HV1) can be controlled by the discharge switch (S1, S1.1, S1.2, S1.3) and the discharge current flowing via the current limiting module (R) is adjustable, and / or wherein for each pair of secondary terminals (A2+, A2-, A3+, A3-) an additional discharge path is provided for the DC link capacitance (C2, C3) of the respective secondary section (HV2, HV3), which leads from the respective first secondary terminal (A2+, A3+) to the respective second secondary terminal (A2-, A3-) and in this respect via the discharge switch (S1, S1.1, S1.2, S1.3) and the current limiting module (R), so that the discharge of the respective DC link capacitance (C2, C3) of the respective secondary section (HV2, HV3) can be controlled by the discharge switch (S1, S1.1, S1.2, S1.3) and the discharge current flowing via the current limiting module (R) is adjustable, and / or wherein each pair of secondary connections (A2+, A2-, A3+, A3-) has a charging path for the DC link capacity (C2, C3) of the respective secondary section (HV2, HV3), which runs from the first primary connection (A1+) to the respective first secondary connection (A2+, A3+) and from the respective second secondary connection (A2-, A3-) to the second primary connection (A1-) and passes through the charging switch (S2) and the current limiting module (R), so that the charging of the respective DC link capacity (C2, C3) of the respective secondary section (HV2, HV3) can be controlled by the charging switch (S2) and the charging current flowing through the current limiting module (R) can be adjusted. [3] Circuit according to claim 1 or 2, furthermore, each first secondary terminal (A2+, A3+) has a first range switch (K2+, K3+) connected in series with it, through which the respective first secondary terminal (A2+, A3+) can be connected to the first primary terminal (A1+), and Each second secondary connection (A2-, A3-) has a second range switch (K2-, K3-) connected in series with it, through which the respective second secondary connection (A2-, A3-) can be connected to the second primary connection (A1-), which are connected to the current limiting module (R), the discharge switch (S1, S1.1, S1.2, S1.3) and the charge switch (S2) in such a way that the discharge of the two-terminal devices (C1, C2, C3) of the primary range (HV1) and of at least one secondary range (HV2, HV3) can be controlled jointly by means of the discharge switch (S1, S1.1, S1.2, S1.3) and the range switches (K2+, K2-, K3+, K3-) and The charging of the intermediate circuit capacities (C2, C3) of at least one secondary range (HV2, HV3) can be controlled jointly by means of the charging switch (S2) and the range switches (K2+, K2-, K3+, K3-). [4] Circuit according to the two preceding claims, wherein the further discharge path provided for each pair of secondary connections (A2+, A2-, A3+, A3-) for the DC link capacitance (C2, C3) of the respective secondary range (HV2, HV3) leads via the respective first range switch (K2+, K3+) and the respective second range switch (K2-, K3-), so that the discharge of the respective DC link capacitance (C2, C3) of the respective secondary range (HV2, HV3) is controllable by the respective range switches (K2+, K2+, K3+, K3-) and the discharge switch (S1, S1.1, S1.2, S1.3), and / or wherein the charging path provided for each pair of secondary connections (A2+, A2-, A3+, A3-) for the DC link capacity (C2, C3) of the respective secondary range (HV2, HV3) leads via the respective first range switch, so that the charging of the respective DC link capacity (C2, C3) of the respective secondary range (HV2, HV3) can be controlled by the respective first range switch (K2+, K3+) and the charging switch (S2). [5] Circuit according to one of the preceding claims, wherein the circuit (1) has at least two pairs of secondary connections (A2+, A2-, A3+, A3-) such that the circuit (1) can be contacted via a first pair of secondary connections (A2+, A2-) with a first secondary area (HV2) which has an intermediate circuit capacitance (C2) and via a second pair of secondary connections (A3+, A3-) with a second secondary area (HV3) which has an intermediate circuit capacitance (C3). [6] Circuit according to one of the preceding claims, each second secondary connection (A2-, A3-) further comprising at least one first reverse current blocking element (D1, D2) downstream of the respective second secondary connection (A2-, A3-), by which a reverse current to the respective second secondary connection (A2-, A3-) is blocked when the charging switch (S2) is closed. [7] Circuit according to one of the preceding claims, both for the first primary terminal (A1+) and each first secondary terminal (A2+, A3+) further comprising at least one second reverse current blocking element (D5, D6, D7) downstream of the respective terminal (A1+, A2+, A3+), by which a reverse current to the respective terminal (A1+, A2+, A3+) is blocked when the discharge switch (S1) is closed. [8] Circuit according to one of the preceding claims, comprising exactly one discharge switch (S1) which is designed and arranged in the circuit to control the discharge of all two-terminal networks (C1, C2, C3). [9] Circuit according to any one of the preceding claims 1 to 7, comprising a discharge switch (S1.1, S1.2, S1.3) for each pair of primary terminals (A1+, A1-) and each pair of secondary terminals (A2+, A2-, A3+, A3-), which are each formed and arranged in the circuit, to control the discharge of the respective two-terminal (C1, C2, C3) of the respective area (HV1, HV2, HV3), such that when an intermediate circuit capacitance (C2, C3) of one of the secondary areas (HV2, HV3) is discharged, the discharge of the two-terminal (C1) of the primary area (HV1) can be controlled independently. [10] Circuit according to any one of the preceding claims 1 to 7, comprising a first discharge switch which is designed and arranged in the circuit (1) to control the discharge of at least one two-terminal device (C1, C2, C3), and comprising a second discharge switch, which is designed and arranged in the circuit (1) to control the discharge of at least two other two-terminal devices (C1, C2, C3). [11] Circuit according to one of the preceding claims, each second secondary connection (A2-, A3-) further comprising at least a third reverse current blocking element (D3, D4) upstream of the respective second secondary connection (A2-, A3-), by which a reverse current not flowing via the current limiting module (R) from the respective second secondary connection (A2-, A3-) to the second primary connection (A1-) is blocked. [12] Circuit according to one of the preceding claims, further comprising a control unit which is designed to control the charging and discharging of the areas (HV1, HV2, HV3) that can be connected to the pair of primary terminals (A1+, A1-) and each pair of secondary terminals (A2+, A2-, A3+, A3-) and is connected in terms of control technology to the discharge switch (S1, S1.1, S1.2, S1.3) and / or the charge switch (S2) and / or at least a part of the area switches (K2+, K2-, K3+, K3-).

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