ELECTRICAL CIRCUIT ARRANGEMENT, MOTOR VEHICLE, AND METHOD FOR OPERATING AN ELECTRICAL CIRCUIT ARRANGEMENT

Abstract

An electrical circuit arrangement is provided comprising an inverter and a filter device, wherein the filter device comprises a control device and an electrical filter circuit hooked up in parallel with a direct current side of the inverter in a direct current subnetwork, wherein at least one resonance frequency of the filter circuit is adjustable, and wherein the control device is designed to actuate the filter circuit in order to adjust the resonance frequency in dependence on at least one piece of load information describing an alternating current load in the direct current subnetwork.

Claims

1. An electrical circuit arrangement, comprising: an inverter; and a filter device, wherein the filter device comprises a control device and an electrical filter circuit hooked up in parallel with a direct current side of the inverter in a direct current subnetwork, wherein at least one resonance frequency of the electrical filter circuit is adjustable, and wherein the control device actuates the electrical filter circuit to adjust the resonance frequency in dependence on at least one piece of load information describing an alternating current load in the direct current subnetwork.

2. The electrical circuit arrangement according to claim 1, wherein the control device is configured to determine, from the load information, at least one frequency of an alternating current component being filtered within a given frequency range, and to adjust the resonance frequency to the frequency so determined.

3. The electrical circuit arrangement according to claim 1, wherein the filter circuit comprises multiple capacitors each being switchable in parallel with the direct current side of the inverter, wherein the resonance frequency of the electrical filter circuit of the control device is adjustable by switching in and/or switching out the capacitors.

4. The electrical circuit arrangement according to claim 3, wherein the capacitors can be switched in and/or switched out each time by a switch element of the electrical filter circuit hooked up in series with the capacitor, wherein the control device is connected to the switch elements and is designed for the switching of the switch elements.

5. The electrical circuit arrangement according to claim 3, wherein at least one resonance frequency formed from the capacitors switched in and at least one line inductance in the direct current subnetwork and/or at least one inductance element of the filter device is adjustable.

6. The electrical circuit arrangement according to claim 1, wherein the direct current subnetwork comprises an electrical energy source, and the electrical filter circuit is arranged in a housing of the electrical energy source.

7. The electrical circuit arrangement according to claim 6, wherein the electrical energy source is a battery or a fuel cell.

8. The electrical circuit arrangement according to claim 1, wherein the load information comprises at least one measured value describing an alternating current portion in the direct current subnetwork and/or at least one operating point information describing a present operating point of the inverter.

9. The electrical circuit arrangement according to claim 1, wherein the electrical circuit arrangement comprises an electrical machine, wherein an alternating current side of the inverter is connected to the electrical machine.

10. A motor vehicle, comprising: an electrical circuit arrangement according to claim 1.

11. A method for operating an electrical circuit arrangement comprising an inverter and a filter device, wherein the filter device comprises a control device and an electrical filter circuit hooked up in parallel with a direct current side of the inverter in a direct current subnetwork, the method comprising: adjusting at least one resonance frequency of the filter circuit in dependence on at least one piece of load information describing an alternating current load in the direct current subnetwork.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0048] Further benefits and details will emerge from the following described embodiments as well as the drawings.

[0049] FIG. 1 shows an embodiment of a motor vehicle comprising an embodiment of an electrical circuit arrangement.

[0050] FIG. 2 shows a circuit diagram of the embodiment of the electrical circuit arrangement according to a method.

DETAILED DESCRIPTION

[0051] FIG. 1 shows an embodiment of a motor vehicle 1. The motor vehicle 1 has an electrical circuit arrangement 2. The electrical circuit arrangement 2 comprises an inverter 3 and a filter device 4, while the filter device 4 comprises a control device 5 and an electrical filter circuit 6. The electrical filter circuit 6 is hooked up in parallel with a direct current side 7 of the inverter 3 and arranged in a direct current subnetwork 8 of the electrical circuit arrangement 2.

[0052] The motor vehicle 1 furthermore comprises an electrical energy source 9, which is connected to the inverter 3 across the direct current subnetwork 8. On an alternating current side 10 of the inverter 3, the latter is connected to an alternating current subnetwork 11 of the motor vehicle, the alternating current subnetwork 11 comprising an electrical machine 12 of the motor vehicle 1. The electrical machine 12 is designed as a traction motor of the motor vehicle 1.

[0053] The electrical energy accumulator 9 is configured, for example, as a high-voltage traction battery of the motor vehicle 1, while the battery potential U.sub.Bat can amount to between 200 V and 1200 V, for example. Alternatively, the energy accumulator 9 can also be configured as a fuel cell. Through the inverter 3, a direct current taken from the electrical energy accumulator 9 can be transformed into a three-phase alternating current for energizing the electrical machine 12.

[0054] Conversely, alternating current produced in a generator mode of the electrical machine 12 can be transformed into a direct current, for example, for charging an energy source 9 designed as a battery.

[0055] FIG. 2 shows a circuit diagram of the electrical circuit arrangement 2. The inverter 3 is designed as a three-phase bridge inverter and comprises three half bridges, each one formed of two switch elements S.sub.1-S.sub.6. Furthermore, the inverter 3 comprises multiple freewheeling diodes D1 to D.sub.6, each one hooked up in parallel with one of the switch elements S.sub.1-S.sub.6. The bridge branches of the respective half bridges form the phases U, V, W, which serve for energizing a three-phase stator winding of the electrical machine 12, not represented here.

[0056] Due to the switching of the switch elements S.sub.1-S.sub.6 during the operation of the inverter 3, alternating current interference may arise, which can retroactively affect the direct current subnetwork 8 of the electrical circuit arrangement 2. The resulting alternating current interference, shown schematically as a current I.sub.AC, can have variable frequencies or variable frequency portions, which depend in particular on the switching frequencies of the switch elements S.sub.1-S.sub.6. In addition or alternatively, the frequencies of the alternating current interference can also depend on the actuation method of the switch elements S.sub.1-S.sub.6 of the inverter 3.

[0057] The inverter 3 can comprise an intermediate circuit capacitor 13 hooked up in parallel at the direct current side 7, the capacitance C of which can be used to filter the alternating current portions or alternating current components in the direct current subnetwork 8. In particular, the intermediate circuit capacitor 13 can serve for filtering of high-frequency interference.

[0058] For example, during operation of the inverter 3 using block timing or block operation of the inverter 3, low-frequency interference can also arise and this can only be inadequately filtered out by the intermediate circuit capacitor 13. This can be the case, in particular, when the switching speed or the clock frequency of the switch elements S.sub.1-S.sub.6 is proportional to the rotary speed of the electrical machine 12, so that, for example, low-frequency alternating current interference may arise in the direct current subnetwork 8 upon starting of the motor vehicle 1 and/or in other situations where a low number of revolutions of the electrical machine 12 exists. The filter device 4 is intended for the additional filtering of this low-frequency interference, its filter circuit 6 being hooked up in parallel with the direct current side 7 of the inverter 3.

[0059] The filter circuit 6 comprises multiple capacitors C.sub.S,1-C.sub.S,n, each of which can be hooked up in parallel with the direct current side 7 of the inverter 3. For this, each of the capacitors C.sub.S,1-C.sub.S,n can be hooked up in parallel with the direct current side 7 of the inverter 3 across a switch element S.sub.C,1-S.sub.C,n hooked up in series with the respective capacitor C.sub.S,1-C.sub.S,n. Accordingly, capacitors C.sub.S,1-C.sub.S,n hooked up in parallel with the direct current side 7 of the inverter 3 can also be cut off or switched out once again by opening the respective switch element S.sub.C,1-S.sub.C,n. The capacitors C.sub.S,1-C.sub.S,n can be designed, for example, as foil capacitors or as electrolyte capacitors. The switch elements S.sub.C,1-S.sub.C,n can be designed as a semiconductor switch or as a transistor, such as an IGBT or as a MOSFET. A design as a relay or contactor is also possible.

[0060] Thanks to the capacitors C.sub.S,1-C.sub.S,n which can be switched in and switched out, the resonance frequency of the filter circuit 6 can be adjusted. For this, the control device 5 of the filter device 4 is adapted to actuate the switch elements S.sub.C,1-S.sub.C,n and switch them, that is, switch them between an open and a closed state. The respective connections between the control device 5 and the switch elements S.sub.C,1-S.sub.C,n are not shown in FIG. 2 for reasons of clarity. The capacitors C.sub.S,1-C.sub.S,n can have different capacitance values, at least in part, and also capacitance values of different orders of magnitude, so that different overall capacitances can be formed from the particular capacitors C.sub.S,1-C.sub.S,n which are switched in.

[0061] The capacitors C.sub.S,1-C.sub.S,n together with the inductance Ls form a drain circuit, the resonance frequency of which can be adjusted by switching in and switching out individual capacitors C.sub.S,1-C.sub.S,n. Thus the frequency of a series resonance of the filter circuit 6 configured as a drain circuit is changed in this way. The inductance Ls can be a line inductance or a stray inductance of at least one electrical line of the direct current subnetwork 8 which connects the filter circuit 6 to the direct current side 7 of the inverter 3. In addition or alternatively, the filter circuit 6 can include an inductance element 14 which is hooked up between the capacitors C.sub.S,1-C.sub.S,n and a terminal on the direct current side, in the present case, a DC-Plus terminal of the inverter 3.

[0062] In order to make possible an adjusting of the resonance frequency of the filter circuit 6 during the run time of the electrical circuit arrangement 2, in one embodiment of a method for operating the electrical circuit arrangement 2, the resonance frequency of the filter circuit 6 is adjusted by the control device 5 in dependence on load information describing an alternating current load in the direct current subnetwork 8.

[0063] From this load information the control device can ascertain the frequency of an alternating current component being filtered, for example, the frequency of the alternating current component with the largest amplitude within a given frequency range. For example, the load information may include at least one measured value describing an alternating current portion in the direct current subnetwork and/or at least one operating point information describing a present operating point of the inverter.

[0064] The control device 4 then adjusts the resonance frequency of the filter circuit 6 in dependence on the ascertained frequency. For this, the capacitors C.sub.S,1-C.sub.S,n can be switched in or switched out in order to establish a resonance frequency of the filter circuit 6 as close as possible to the ascertained frequency. For this, a single one of the capacitors C.sub.S,1-C.sub.S,n can be switched in, or a subset or all of the capacitors C.sub.S,1-C.sub.S,n can be switched in. The ascertained frequency of the alternating current component being filtered can be established as accurately as possible, or the capacitors C.sub.S,1-C.sub.S,n will be switched in such that the deviation from the ascertained frequency is as slight as possible.

[0065] The adjusting of the resonance frequency has the effect that the filter circuit, that is, the drain circuit formed by the inductance Ls and the capacitors C.sub.S,1-C.sub.S,n, has an absolute or at least a local, frequency-dependent impedance minimum at the ascertained frequency. In this way, the alternating current interference I.sub.AC can be drained by the filter circuit 6, without burdening the energy source 9.

[0066] In order to ascertain the load information, the control device 4 can be connected to a current sensor 15, by which at least the alternating current portion I.sub.AC in the direct current subnetwork 8 can be measured. In addition or alternatively, the load information can involve operating point information describing the present actuation of the inverter 3 and/or the present switching frequency of the switch elements S.sub.1-S.sub.6 of the inverter 3. The control device 5 may obtain the operating point information, for example, from another controller (not shown) of the motor vehicle 1 via a communication link (not shown), the other controller being adapted, e.g., to operate the inverter 3.

[0067] Alternatively, the control device 5 can also be designed to operate the inverter 3 and can itself ascertain the corresponding operating point information of the inverter 3, especially on the basis of measured values and/or operator input ascertained, for example, in preparation of a driving operation of the motor vehicle 1. The adjusting of the resonance frequency of the filter circuit 6 will be done continuously during the operation of the motor vehicle 1 by switching in and/or switching out individual capacitors C.sub.S,1-C.sub.S,n depending on the present operating state of the inverter 3. This makes possible the best possible interference compensation of alternating current interference in the direct current subnetwork 8 during a driving operation of the motor vehicle 1, accompanied by changing numbers of revolutions of the electrical machine 12 and different switching frequencies of the switch elements S.sub.1-S.sub.6 of the inverter 3 and/or different operating point-dependent actuation or modulation methods of the inverter 3.

[0068] The filter circuit 6 can be arranged in a housing 16 of the electrical energy source 9. Alternatively, the filter circuit 6 can also be arranged elsewhere in the direct current subnetwork 8. The control device 5 of the filter device 4 can likewise be arranged inside the housing 16.

[0069] Alternatively, the control device 5 can also be arranged elsewhere inside the motor vehicle 1. German patent application no. 10 2022 107475.7, filed Mar. 30, 2022, to which this application claims priority, is hereby incorporated herein by reference in its entirety.

[0070] Aspects of the various embodiments described above can be combined to provide further embodiments. In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled.