DE102021102950A1 - Active filter in the semiconductor module - Google Patents

Abstract

Proposed is a power stage (1) for driving an electric motor, preferably a power stage (1) of a voltage converter or a converter or an inverter or a cruise controller for driving an electric motor or traction motor of an electric vehicle, comprising a controllable or switchable power semiconductor (10) which has a Supply line (20) is supplied with electrical energy, and a heat sink (11) thermally connected to the power semiconductor (10), and a housing (12) for holding and/or accommodating the power semiconductor (10) and the heat sink (11), and a first capacitor (31) for suppressing high-frequency interference, the first capacitor (31) being connected between the supply line (20) and the housing (12). It is essential that an active filter (35) is connected between the supply line (20) of the power semiconductor (10) and the heat sink (11).

Description

The invention relates to a power stage for controlling an electric motor, in particular a traction motor in a vehicle, having the features of the preamble of claim 1.

Y-capacitors, which are arranged between a supply line and a housing, are used to suppress interference from known power stages. A disadvantage of known circuits with Y-capacitors for suppressing common-mode interference is that the Y-capacitors must have high capacitance values for adequate interference suppression. In high-voltage systems in particular, however, the Y-capacitor within a system may only assume a certain maximum capacitance value in order to keep the electrical energy stored in the capacitor below a prescribed limit value for safety reasons. The resulting maximum possible value of the Y capacitor means that adequate interference suppression is only possible in a limited frequency range. As a result, additional filter measures that require a great deal of cost and installation space are necessary.

Furthermore, active filters are already known, which are arranged between a supply line and a housing, with large simulated currents being necessary to suppress interference from the power stage.

The object of the invention is to provide a power stage for controlling an electric motor with improved interference suppression properties, which preferably has a small overall volume and good suppression for a wide frequency range, i.e. also for high-frequency interference signals.

According to the invention, this object is achieved by a power stage having the features of claim 1 .

According to the invention, a power stage for driving an electric motor is provided, preferably a power stage of a voltage converter or a converter or an inverter or a speed controller for driving an electric motor or traction motor of an electric vehicle. The power stage comprises a controllable or switchable power semiconductor, which is supplied with electrical energy via a supply line, and a heat sink thermally connected to the power semiconductor, and a housing for holding and/or accommodating the power semiconductor and the heat sink, and a first capacitor for suppressing high-frequency Disturbances, wherein the first capacitor is connected between the supply line and the housing. It is essential that an active filter is connected between the supply line of the power semiconductor and the heat sink.

It is advantageous that an active filter is formed close to the power semiconductor in addition to the first capacitor. In this way, interference signals are returned to the interference source or suppressed by the first capacitor between the supply line and the housing. According to the capacitance of the first capacitor, it can tend to dampen lower interference frequencies with a larger capacitance, and tend to dampen interference signals with a higher frequency with a smaller capacitance. Interference signals with higher frequencies and/or in a wider frequency band, for example in a range from 10 kHz to 100 MHz, preferably in a range from 20 kHz to 50 MHz, are diverted or suppressed by the active filter between the supply line and the heat sink. As a result, interference in a wide frequency band can be effectively suppressed. The frequency above which interference signals are more likely to be derived or suppressed by the first capacitor or the active filter depends on the capacitance values and the ratio of the two components to one another. In particular, the first capacitor can be in the form of a Y capacitor.

In an advantageous embodiment, provision can be made for the active filter to be arranged in the immediate vicinity of the power semiconductor. Apart from the supply line, no further component is preferably formed between the active filter and the power semiconductor. Apart from the heat sink and/or an insulator, no further component is preferably formed between the active filter and the power semiconductor. Due to the proximity of the active filter to the power semiconductor, the currents required to suppress the interference signals can be kept smaller in comparison to already known circuits with an active filter. Another advantage is that the short lines between the power semiconductor, i.e. the source of interference, and the active filter minimize the emission of interference. As a result, better interference suppression is obtained, particularly in the higher frequency range, preferably in the frequency range greater than 1 MHz. Short lines mean in particular lines shorter than 10 cm, preferably 5 cm, or lines shorter than 1/10 or 1/30 or 1/50 of the wavelength of an interference radiation, corresponding to the fundamental oscillation of the switching frequency, preferably the maximum switching frequency, of the power semiconductor. i.e. in particular without considering harmonics.

Preferably, the active filter includes an amplifier and may be a single-stage or multi-stage active filter. In particular, the active filter causes an interference signal picked up on a supply line to be amplified in an amplifier circuit and fed back into the supply line with the opposite polarity as a correction signal. This dampens or suppresses the interference signal. A combination of a passive filter circuit with an active filter is also conceivable.

In one configuration it can be provided that the active filter is arranged on the same circuit board or the same circuit board as the power semiconductor.

Provision can be made for the active filter to be connected to the heat sink in a manner that provides good electrical conductivity, and for the active filter to be connected to the heat sink in a manner that is good thermal insulation at the same time. This means that the active filter is electrically conductively connected to the heat sink and is thermally insulated from the heat sink. Connections with good electrical conductivity are, for example, connections with an electrical resistance of less than 1 ohm, preferably less than 0.5 ohm, most preferably less than 0.1 ohm. Connections with good thermal insulation are, for example, arrangements or connections with a thermal resistance of 1 KAN, preferably 0.5 K/W, most preferably 0.1 K/W. Advantageously, the poor thermal conduction prevents the active filter from heating up. In particular, the active filter is arranged and/or connected to the heat sink in such a way that the temperature of the active filter is lower than the temperature of the heat sink. For example, the active filter can be connected to its own heat sink, in particular to keep the temperature of the active filter low.

Provision can be made for the power semiconductor to be attached to the heat sink in an electronically insulated manner, for example screwed, or glued, or clamped.

The supply line can be a high-voltage line. In particular, the supply line can have a voltage of ≧50 V, preferably a voltage of ≧200 V, most preferably a voltage of ≧400 V.

Provision can advantageously be made for an insulator to be formed between the heat sink and the housing in order to electrically isolate the heat sink and the housing in such a way that the heat sink and the housing with the insulator form a second capacitor. Alternatively or additionally, a second capacitor can be arranged between the heat sink and the housing. The second capacitor creates a low contact resistance or a bridge between the insulator and the housing for AC voltages or high-frequency interference.

Aluminum oxide, thermal silicon, PPL (polypropylene), PE (polyethylene), plastics, Teflon (polytetrafluoroethylene), air and/or air foam can preferably be used as the insulator. Preferably, in configurations in which the heat sink and the housing form a capacitor with an insulator lying between them, the upper limit of the distance between the heat sink and the housing is a maximum of 2 cm. Most preferably, the distance may be a maximum of 10% of the edge length of the heat sink. For example, the distance between the heat sink and the housing can be in the range between 0.5 mm and 5 mm.

In a preferred embodiment, it can be provided that the first capacitor and/or the active filter and/or the second capacitor each form an interference suppression module.

In particular, one configuration can provide that an interference suppression module or an interference suppression arrangement is formed from a series connection of the active filter and second capacitor, and a parallel connection of the first capacitor with the series-connected active filter with the second capacitor. In this case, the first capacitor can be designed to suppress higher frequencies. In particular, the capacitance of the capacitor can be lower than the capacitance of a comparable conventional Y-capacitor. The first capacitor can thus, for example, suppress interference signals with a higher frequency. Low frequencies can be attenuated via the active filter. As a result, a wide range of interference frequencies, in particular from low interference frequencies, for example in the KHz range, to high interference frequencies, for example in the 100 MHz or 1 GHz range, can be damped. At the same time, it is ensured that the electrical energy stored in the first capacitor remains below a specific limit value even in the case of high voltages on the supply line. As a result, a high level of safety can be guaranteed even with high supply voltages and good interference signal damping. The active filter can be used to effectively suppress a wide frequency band. Due to the series connection of the active filter with the second capacitor, which has a relatively small capacitance, the capacitance resulting from this series connection for the supply line remains low, so that the total energy stored remains high even with high spans ments of the supply line remains below a certain limit value.

The insulator, i.e. the galvanic separation between the heat sink and the housing, means that interference, in particular low-frequency interference, cannot be conducted unhindered from the heat sink into the base plate or the housing and can therefore not be radiated from there into other components. Although high-frequency interference can pass through the second capacitor, it is effectively suppressed by the first capacitor and/or the active filter. This further improves the interference suppression, even for high frequencies.

It can be provided that the first capacitor has a capacitance in the range from 100 nF to 5 nF, preferably has a capacitance in the range from 80 nF to 10 nF, most preferably has a capacitance in the range from 50 nF to 20 nF.

Provision can be made for the second capacitor to have a capacitance in the range between 10 pF and 100 nF, preferably a capacitance in the range between 20 pF and 20 nF.

Provision can be made for the capacitance of the second capacitor to be dimensioned in such a way that the maximum energy stored in the interference suppression modules is ≦300 mJ, preferably ≦200 mJ, most preferably ≦150 mJ. The maximum energy stored in the interference suppression modules can correspond to a predetermined limit value or be below it.

Contact is usually made with the first capacitor or the active filter via connection lines, which in turn have a specific inductance. This inductance can lead to undesired resonance effects at certain frequencies, particularly higher frequencies. Efforts are therefore made to keep the connection inductance as low as possible, for example by appropriate, in particular straight line routing and/or the use of correspondingly large line cross sections. In particular, it can be provided that the connection inductance of the active filter to the heat sink is in the range from 1 nH to 100 nH, preferably in the range between 5 nH and 50 nH.

It can be provided that the supply line is multi-pole and that a first capacitor is connected between the housing and the several poles of the supply line, preferably all poles of the supply line, and that between the heat sink and several poles of the supply line, preferably all poles of the Supply line, in each case an active filter is connected. With this arrangement, both single-pole supply lines and multi-pole supply lines can be suppressed.

It can be provided that the active filter comprises an amplifier circuit with a preliminary stage, the input of which is connected symmetrically to the supply line by means of a galvanically isolated tap in order to tap off an interference signal, and with an output stage controlled by the preliminary stage, whose output is connected via an output capacitor in each case is symmetrically connected to the heat sink in order to feed in a correction signal, the interference signal being tapped off and the correction signal being fed in in each case at the same point on a supply line. The tap and the feed are galvanically isolated. The galvanic isolation between the amplifier and the supply line where the interference signal is picked up and when the correction signal is coupled in allows the amplifier to be operated at a lower voltage level than the supply line to be filtered. As a result, the device according to the invention can also be used at high voltages.

When the interference signal is tapped and the correction signal is fed in at the same point on a supply line or the heat sink, it is understood that the interference signal is tapped off and the correction signal is fed in at the same potential, preferably at the same spatial point, preferably via the same connection point. Thus, the same location means the same AC potential, the same DC potential, and the same mechanical location.

It can be provided that the amplifier circuit has an active filter with discrete semiconductors, preferably transistors. As a result, the components of the active filter are significantly smaller and also cheaper and, in preferred embodiments, can be arranged on the circuit board of the power semiconductor.

In order to achieve high interference signal suppression when the sensor signal is tapped and the correction signal is fed in at the same point, it is preferably provided that the amplifier has a short signal propagation time. This minimizes phase shifts between the interference signal and the correction signal. In this way, in particular, transient or stochastic interference can also be suppressed very well. Conventional active filters have a correspondingly long settling time and are not suitable for suppressing transient or stochastic interference. In particular, it can be provided that the amplifier circuit has a signal propagation time between input and output which is less than or equal to 20 ns, preferably less than or equal to 10 ns, most preferably less than or equal to 6 ns. This enables good suppression of interference signals up to a high frequency range, preferably up to 4 MHz and above. The frequency range with the best interference signal suppression can preferably be between 1 Hz and 10 MHz, most preferably between 100 kHz and 4 MHz.

In one embodiment, it can be provided that the preliminary stage is constructed as a single-stage or two-stage amplifier. Provision can preferably be made for the preliminary stage to form a low-pass filter or band-pass filter. The amplifier can be constructed as an active filter with discrete semiconductors, preferably transistors and/or field effect transistors. The bandpass filter, preferably using RC elements or LC elements in the transmission path, limits the useful frequency of the device below (low frequencies) and prevents the amplifier from oscillating when it increases (higher frequencies) by lowering the gain in the high frequency range.

Provision can be made for the output stage to be designed as a push-pull output stage and/or as a current mirror.

In order to increase the output current, it can be provided that the output stage can be cascaded or that the pre-stage controls a plurality of cascaded output stages. In particular, it can be provided that the preliminary stage controls two cascaded output stages or up to eight cascaded output stages.

The object is further achieved by a traction network of a vehicle, comprising a battery or a rechargeable battery, a traction motor and an inverter connected to the traction motor for controlling the traction motor, and a supply line running between the battery and the inverter, it being provided in particular that the inverter has a Has power stage according to one of the preceding embodiments.

Provision can be made for a choke to suppress high-frequency interference to be arranged in the supply line between the battery and inverter and/or for a choke to suppress high-frequency interference to be arranged in a supply line between the inverter and traction motor.

In one configuration, it can be provided that the supply line and the heat sink either have a choke between the point at which the interference signal is picked up and the voltage source and/or have a higher impedance than between the point at which the interference signal is picked up and a source of interference.

The choke represents an increased inductance and prevents the supplied correction signal from being loaded by a small impedance of the power source. Increased interference signal suppression is thus achieved via the choke. By tapping and feeding at the same point, a particularly simple implementation of the device in existing systems is achieved at the same time with high interference signal suppression. An adjustment or a change of existing supply lines is not necessary. In addition, the supply line, on which high power is transported, does not have to be routed via the amplifier. This reduces EMC problems and retrofitting existing systems is greatly simplified.

• 1: ein erstes Ausführungsbeispiel einer erfindungsgemäßen Leistungsstufe mit einer Versorgungsleitung;
• 2: ein zweites Ausführungsbeispiel einer erfindungsgemäßen Leistungsstufe mit mehreren Versorgungsleitungen;
• 3: ein drittes Ausführungsbeispiel einer erfindungsgemäßen Leistungsstufe mit einer Versorgungsleitung und galvanisch isoliertem Kühlkörper;
• 4: ein viertes Ausführungsbeispiel einer erfindungsgemäßen Leistungsstufe mit mehreren Versorgungsleitungen und galvanisch isoliertem Kühlkörper;
• 5: Darstellung einer Schaltung des dritten Ausführungsbeispiels aus 3;
• 6a: Simulation der Störunterdrückung ohne aktiven Filter;
• 6b: Simulation der Störunterdrückung durch das dritte Ausführungsbeispiel aus 3;
• 7: Simulation des Zeitverlaufs in dem dritten Ausführungsbeispiel aus 3.

Further configurations of the invention are shown in the figures and described below. show:

• 1 : a first exemplary embodiment of a power stage according to the invention with a supply line;
• 2 : a second exemplary embodiment of a power stage according to the invention with a plurality of supply lines;
• 3 : a third exemplary embodiment of a power stage according to the invention with a supply line and a galvanically isolated heat sink;
• 4 : a fourth exemplary embodiment of a power stage according to the invention with a plurality of supply lines and a galvanically isolated heat sink;
• 5 : Representation of a circuit of the third embodiment 3 ;
• 6a : simulation of interference suppression without an active filter;
• 6b : simulation of noise suppression by the third embodiment 3 ;
• 7 : Simulation of the passage of time in the third embodiment 3 .

1 shows a first exemplary embodiment of a power stage 1 according to the invention. A power semiconductor 10 is thermally connected to a heat sink 11 and the heat sink 11 is arranged to a housing 12. A first insulator 13 can preferably be arranged between the power semiconductor 10 and the heat sink 11, with heat transfer between Power semiconductor 10 and heat sink 11 are preserved as well as possible despite the insulator 13 remains to dissipate the heat of the power semiconductor 10 via the heat sink 11.

The power semiconductor 10 in 1 is supplied with electrical energy via a supply line 20, for example by a battery. An interference suppression module 30 is arranged between the supply line 20 and the housing 12 .

The interference suppression module 30 sits in 1 composed of a first capacitor 31 and an active filter 35 which are connected in parallel to each other.

The first capacitor 31 is arranged between the supply line 20 and the housing 12 . The active filter 35 is arranged between the supply line 20 and the heat sink 11 . In this case, the first capacitor 31 can be designed to suppress higher frequencies. In particular, the capacitance of the first capacitor 31 can be lower than the capacitance of a comparable conventional Y-capacitor. The first capacitor 31 can thus, for example, suppress interference signals with a higher frequency. Low frequencies can be attenuated via the active filter 35 . As a result, a wide range of interference frequencies, in particular from low interference frequencies, for example in the KHz range, to high interference frequencies, for example in the 100 MHz or 1 GHz range, can be damped. At the same time, it is ensured that the electrical energy stored in the first capacitor remains below a specific limit value even in the case of high voltages on the supply line. As a result, a high level of safety can be guaranteed even with high supply voltages and good interference signal damping. The active filter 35 can be used to effectively suppress a wide frequency band.

2 shows a second exemplary embodiment of a power stage 1 according to the invention. The power stage 1 in 2 differs from power level 1 in 1 only in that the power semiconductor 10 is supplied with electrical energy via two supply lines 20 and, furthermore, two first capacitors 31 and two active filters 35 are formed.

The first capacitors 31 in 2 are each arranged between the first supply line 20 and the housing 12 . The active filters 35 in 2 are each arranged between the first supply line 20 and the heat sink 11 . What is essential here is that each supply line 20 is connected once to the housing 12 and once to the heat sink 11 via a respective first capacitor 31 and an active filter 35 . More than two supply lines 20 can preferably also be connected to the power semiconductor 10 , with each supply line 20 being connected to the heat sink 11 and the housing 12 via a first capacitor 31 and an active filter 35 .

3 shows a third exemplary embodiment of a power stage 1 according to the invention. The power stage 1 in 3 differs from power level 1 in 1 only in that the heat sink 11 is galvanically isolated from the housing 12 . A second insulator 14 is arranged between the heat sink 11 and the housing 12 .

In 3 a second capacitor 32 is formed between the heat sink 11 and the case 12 . This second capacitor 32 can be formed by the arrangement of the heat sink 11 and the housing 12 and the second insulator 14 lying therebetween. Embodiments are also possible in which the second capacitor 32 is arranged between the heat sink 11 and the housing 12 .

In 3 the interference suppression module 30 is formed from a parallel circuit of the first capacitor 31 with the series-connected active filter 35 and second capacitors 32 . The capacitance of the second capacitor 32 is dimensioned such that the maximum energy stored in the interference suppression module 30 is ≦300 mJ, preferably ≦200 mJ, most preferably ≦150 mJ.

4 is a fourth exemplary embodiment of a power stage 1 according to the invention. The power stage 1 in 4 differs from power level 1 in 3 only in that the power semiconductor 10 is supplied with electrical energy via two supply lines 20 and, furthermore, two first capacitors 31 and two active filters 35 are formed.

The first capacitors 31 in 4 are each arranged between the first supply line 20 and the housing 12 . The active filters 35 in 4 are each arranged between the first supply line 20 and the heat sink 11 . It is essential that each supply line 20 is connected to the housing 12 via a respective capacitor 31 and to the heat sink 11 via the active filter 35 . More than two supply lines 20 can preferably also be connected to the power semiconductor 10 , with each supply line 20 being connected to the heat sink 11 and the housing 12 via a first capacitor 31 and an active filter 35 .

The interference suppression module 30 of the first supply line 20 in 4 is formed from a Parallel connection of the first capacitor 31 of the first supply line 20 with the series-connected active filter 35 of the first supply line 20 and the second capacitor 32. The interference suppression module 30 of the second supply line 20 in 4 is formed from a parallel connection of the first capacitor 31 of the second supply line 20 with the series-connected active filter 35 of the second supply line 20 and the second capacitor 32.

5 FIG. 14 is a circuit diagram of the third embodiment of FIG 3 . The power stage 1 is arranged between a battery 40 and a motor 41 and is connected to them via the supply line 20 . In 5 the coils represent the parasitic inductances of the lines, connections and busbars.

The preferably formed first insulator 13 between the power semiconductor 10 and the heat sink 11 in the 1 until 5 galvanically separates the heat sink and the housing from each other. Embodiments are possible in which a third capacitor 33 is formed by the arrangement of the power semiconductor 10, the heat sink 11 and the first insulator 13.

6b FIG. 12 shows simulation results of the third embodiment 3 with a circuit according to 5 ie with an active filter 35, whereas the 6a Simulation results without an active filter 35 shows.

7 shows the time development of a signal with the light gray line for a circuit according to 5 with active filter 35 and with a black line for a circuit without active filter 35.

Reference List

1

power level

10

power semiconductors

11

heatsink

12

Housing

13

first insulator

14

second insulator

20

supply line

30

interference suppression module

31

first capacitor

32

second condenser

33

third capacitor

35

active filter

40

battery

41

engine

Claims (14)

Power stage (1) for driving an electric motor, preferably power stage (1) of a voltage converter or a converter or an inverter or a speed controller for driving an electric motor or traction motor of an electric vehicle, comprising a controllable or switchable power semiconductor (10) which is connected via a supply line (20 ) is supplied with electrical energy, and a heat sink (11) thermally connected to the power semiconductor (10), and a housing (12) for holding and/or accommodating the power semiconductor (10) and the heat sink (11), and a first capacitor (31) for suppressing high-frequency interference, the first capacitor (31) being connected between the supply line (20) and the housing (12), characterized in that an active filter (35) is connected between the supply line (20) of the power semiconductor (10 ) and the heat sink (11) is connected. Performance level (1) according to claim 1 , characterized in that the active filter (35) is arranged in the immediate vicinity of the power semiconductor (10), preferably no other component apart from the supply line (20) is formed between the active filter (35) and the power semiconductor (10), most preferably apart from the heat sink (11) and/or an insulator (12), no other component is formed between the active filter (35) and the power semiconductor (10). Performance level (1) according to claim 1 or 2 , characterized in that the active filter (35) comprises an amplifier and is designed as a single-stage or multi-stage active filter (35). Power stage (1) according to one of the preceding claims, characterized in that the active filter (35) is arranged on the same circuit board or circuit board as the power semiconductor (10). Power stage (1) according to one of the preceding claims, characterized in that the active filter (35) is connected to the heat sink (11) with good electrical conductivity, and that the active filter (35) is connected to the heat sink (11) with good thermal insulation preferably that the active filter (35) is thermally insulated from the heat sink (11) and/or that the power semiconductor (10) is attached to the heat sink (11) in an electronically insulated manner, for example screwed, or glued, or clamped. Power stage (1) according to one of the preceding claims, characterized in that the supply line (20) is a high-voltage line, preferably that the supply line (20) has a voltage ≥ 50 V, preferably a voltage ≥ 200 V, most preferably a voltage ≥ 400 V having. Power stage (1) according to one of the preceding claims, characterized in that an insulator (12) is formed between the heat sink (11) and the housing (12) in order to electrically isolate the heat sink (11) and the housing (12) in such a way that the heat sink (11) and the housing (12) with the insulator (12) form a second capacitor (32), preferably that a second capacitor (32) can be arranged between the heat sink (11) and the housing (12). Power stage (1) according to one of the preceding claims, characterized in that the first capacitor (31) and/or the active filter (35) and/or the second capacitor (32) each form an interference suppression module (30), preferably that the interference suppression module (30) or an interference suppression arrangement formed from a series circuit of the active filter (35) and the second capacitor (32), and a parallel circuit of the first capacitor (31) with the active filter (35) connected in series with the second capacitor (32). is. Power stage (1) according to one of the preceding claims, characterized in that the first capacitor (31) has a capacitance in the range from 100 nF to 5 nF, preferably a capacitance in the range from 80 nF to 10 nF, most preferably a capacitance in the range from 50 nF to 20 nF, and/or that the second capacitor (32) has a capacitance in the range between 10 pF and 100 nF, preferably a capacitance in the range between 20 pF and 20 nF, and/or that the capacitance of the second capacitor (32) is dimensioned such that the maximum energy stored in the interference suppression modules (20) is ≦300 mJ, preferably ≦200 mJ, most preferably ≦150 mJ, and/or that the connection inductance of the active filter (35) to the heat sink (11) is in the range from 1 nH to 100 nH, preferably in the range between 5 nH and 50 nH. Power stage (1) according to one of the preceding claims, characterized in that the supply line (20) has multiple poles and that between the housing (12) and the plurality of poles of the supply line (20), preferably all poles of the supply line (20), one first capacitor (31) is connected, and in that an active filter (35) is connected between the heat sink (11) and several poles of the supply line (20), preferably all poles of the supply line (20). Power stage (1) according to one of the preceding claims, characterized in that the active filter (35) comprises an amplifier circuit with a pre-stage, the input of which is connected symmetrically to the supply line (20) by means of a galvanically isolated tap in order to tap off an interference signal, and with an output stage controlled by the pre-stage, the output of which is symmetrically connected to the heat sink (11) via an output capacitor in each case in order to feed in a correction signal, the interference signal being tapped off and the correction signal being fed in each time at the same point on a supply line (20). Power stage (1) according to one of the preceding claims, characterized in that the amplifier circuit has an active filter (35) with discrete semiconductors, preferably transistors. Traction network of a vehicle, comprising a battery (40) or a rechargeable battery, a traction motor (41) and an inverter connected to the traction motor (41) for controlling the traction motor (41) and a supply line (20 ), characterized in that the inverter has a power stage (1) according to one of the preceding exemplary embodiments. traction network Claim 13 , characterized in that a choke for suppressing high-frequency interference is arranged in the supply line (20) between the battery (40) and the inverter and/or in that a choke for suppressing high-frequency interference is arranged in a supply line (20) between the inverter and traction motor (41). is.

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