DE102024207034B4 - Traction network and EMC filter - Google Patents

Abstract

Traction network (1) of an electric or hybrid vehicle, comprising a DC voltage source (2), at least one intermediate circuit capacitor (5), an inverter (6) and a separately excited synchronous machine (8), wherein a first EMC filter (12) is arranged between the inverter (6) and the DC voltage source (2), wherein power electronics (10) are provided which are configured to generate a rotor current for rotor windings (9) of the separately excited synchronous machine (8), wherein a second EMC filter (13) is arranged between the power electronics (10) and the rotor windings (9), wherein the first EMC filter (12) and the second EMC filter (13) are arranged in a common housing (11) and share at least one component, wherein the at least one shared component is at least a soft magnetic core (16).

Description

The invention relates to a traction network for an electric or hybrid vehicle and an EMC filter.

Traction systems for electric and hybrid vehicles consist of a DC power supply, at least one intermediate circuit capacitor, an inverter, and an electric motor. The DC power supply is usually a high-voltage battery. The inverters are typically pulse-width modulated (PWM) inverters, which can be configured as two- or three-level pulse inverters. The electric motor can be either asynchronous or synchronous. Synchronous motors can be separately excited or permanent magnet synchronous. The advantage of separately excited synchronous motors is that the rotor field can be switched off, eliminating the need for rare earth elements, although the rotor current must still be supplied.

Especially when using pulse-width modulation (PWM) inverters, the rapid, steep switching edges generate interference radiation. This problem is exacerbated if the high-voltage lines between the high-voltage battery and the PWM inverter are unshielded, as they then act like an antenna. Furthermore, this RF interference is damaging to many components. Therefore, it is common practice to use EMC filters to minimize RF interference. Various types of EMC filters are available. For example, there are active and passive EMC filters, which can also be used in combination. One such combination is shown, for example, in the... DE 10 2017 223 763 A1 known.

One proposed design is a passive EMC filter with two ferrite rings through which the high-voltage lines are routed, or which are wound around the ferrite rings in opposite directions. Y-capacitors are arranged between the two ferrite rings, connected to ground.

Another configuration involves an X-capacitor on the high-voltage battery side, a common-mode choke followed by two Y-capacitors and another X-capacitor. Concepts are also known that additionally incorporate ohmic resistors.

The pulse inverter not only generates RF interference on the DC side but also on the AC side of the electric machine, so it is also known to use EMC filters on the AC side.

From the CN 1 11 446 902 A An EMC filter is known that integrates an EMC filter on the DC voltage side and an EMC filter on the AC voltage side in a common housing.

When using separately excited synchronous machines, additional power electronics are required to provide the rotor current. Here, too, it has already been proposed to use an EMC filter between the rotor winding and the power electronics.

From the US 2007/0 240 662 A1 A traction network for an electric or hybrid vehicle is known, comprising a DC voltage source, at least one intermediate circuit capacitor, an inverter, and a separately excited synchronous machine. Power electronics are provided, configured to generate a rotor current for the rotor windings of the separately excited synchronous machine. A diode is connected in parallel with the rotor winding.

From the DE 10 2020 124 095 A1 A control arrangement for controlling a separately excited synchronous machine is known, comprising an inverter for controlling stator windings of the synchronous machine and an excitation circuit for electrically controlling rotor windings of the synchronous machine, wherein a DC side of the inverter is connected to a DC side of the excitation circuit via two connecting lines. The line inductance and/or line capacitance of the connecting lines between the inverter and the excitation circuit are adjustable.

From the DE 10 2021 102 334 A1 Another traction network with a separately excited synchronous machine is known, wherein an EMC filter is arranged between an excitation unit and the rotor coil.

The invention is based on the technical problem of improving the compactness of a traction network with a separately excited synchronous machine and creating a corresponding EMC filter.

The solution to the technical problem is achieved by a traction network with the features of claim 1 and an EMC filter with the features of claim 4. Further advantageous embodiments of the invention are set forth in the dependent claims.

The traction network of an electric or hybrid vehicle comprises a DC voltage source, at least one intermediate circuit capacitor, an inverter, and a separately excited synchronous machine, with a connection between the inverter and A first EMC filter is arranged at the DC voltage source. The DC voltage source is preferably a high-voltage battery, and the inverter is preferably a pulse-width modulated inverter. Furthermore, power electronics are provided, configured to generate a rotor current for the rotor windings of the separately excited synchronous machine, with a further EMC filter arranged between the power electronics and the rotor windings. The first EMC filter and the second EMC filter are arranged in a common housing, and at least one component is shared.

By arranging them together in one housing and sharing components, the design can be more compact and costs can be saved; for example, shared cooling of the two filters can be provided.

In one embodiment, the at least one common component is at least one soft magnetic core, in particular a ferrite ring. The two pairs of conductors can be wound in opposite directions around the at least one soft magnetic core (as a common-mode choke) or simply pass through, as in the DE 10 2017 223 763 A1 described.

In another embodiment, the first EMC filter and the second EMC filter are arranged on a common circuit board. Capacitors and/or resistors may be shared in this configuration.

The EMC filter has two first inputs for a first interference source and two second inputs for a second interference source. Furthermore, the EMC filter has two first outputs and two second outputs, comprising a first EMC filter and a second EMC filter. The first EMC filter is located between the first inputs and first outputs, and the second EMC filter is located between the second inputs and second outputs. The EMC filter has a housing, and at least one component is shared by both the first and second EMC filters. For further details, please refer to the preceding descriptions.

• 1 ein schematisches Blockschaltbild eines Traktionsnetzes und
• 2 eine schematische Darstellung eines EMV-Filters

The invention is explained in more detail below with reference to a preferred embodiment. The figures show:

• 1 a schematic block diagram of a traction network and
• 2 a schematic representation of an EMC filter

In the 1 Figure 1 shows a schematic block diagram of a traction network 1 of an electric or hybrid vehicle. The traction network 1 comprises a DC voltage source 2 in the form of a high-voltage battery 3, an EMC filter, at least one DC link capacitor 5, an inverter 6 in the form of a pulse inverter 7, a separately excited synchronous machine 8 with rotor windings 9, and additional power electronics 10. The EMC filter 4 has a housing 11. Furthermore, the EMC filter 4 has two first inputs E1 and two first outputs A1. The EMC filter 4 also has two second inputs E2 and two second outputs A2. The second inputs E2 are connected to the additional power electronics 10, and the two second outputs are connected to the rotor windings 9 of the separately excited synchronous machine 8. The additional power electronics 10 generates the rotor current for the rotor windings 9. The EMC filter 4 suppresses RF interference on the high-voltage lines HV+, HV- as well as in the rotor current.

In the 2 The EMC filter 4 is shown in a highly simplified manner, with inputs E1 and E2 depicted on the same side, although this is not mandatory. The EMC filter 4 comprises a first EMC filter 12 and a second EMC filter 13, both arranged on a common circuit board 14. The first EMC filter 12 has an X-capacitor C _X1 at each of inputs E1 and outputs A1; these capacitors can have different values. Furthermore, the first EMC filter 12 has two Y-capacitors C _Y1 connected to ground. A common-mode choke 15, which has a soft magnetic core 16, is arranged between the X-capacitors C _X1 . Accordingly, the second EMC filter 13 has two X capacitors C _X2 , two Y capacitors C _Y2 and a common-mode choke 17, with the two common-mode chokes 15, 17 utilizing the common soft magnetic core 16. The EMC filters 12, 13 can also have and utilize multiple soft magnetic cores 16.

Reference symbol list

1

Traction network

2

DC voltage source

3

High-voltage battery

4

EMC filter

5

Intermediate circuit capacitor

6

inverter

7

Pulse inverter

8

Externally excited synchronous machine

9

Rotor windings

10

further power electronics

11

Housing

12

first EMC filter

13

second EMC filter

14

Circuit board

15

Common-mode choke

16

soft magnetic core

17

Common-mode choke

A1

first exits

A2

second exits

CX1

X-capacitor

CY1

Y-capacitor

CX2

X-capacitor

CY2

Y-capacitor

E1

first entrances

E2

second entrances

HV+, HV

High-voltage lines

Claims (4)

Traction network (1) of an electric or hybrid vehicle, comprising a DC voltage source (2), at least one intermediate circuit capacitor (5), an inverter (6) and a separately excited synchronous machine (8), wherein a first EMC filter (12) is arranged between the inverter (6) and the DC voltage source (2), wherein power electronics (10) are provided which are configured to generate a rotor current for rotor windings (9) of the separately excited synchronous machine (8), wherein a second EMC filter (13) is arranged between the power electronics (10) and the rotor windings (9), wherein the first EMC filter (12) and the second EMC filter (13) are arranged in a common housing (11) and share at least one component, wherein the at least one shared component is at least a soft magnetic core (16). Traction network after Claim 1 , characterized in that the first EMC filter (12) and the second EMC filter (13) are arranged on a common printed circuit board (14). EMC filter (4), wherein the EMC filter (4) has two first inputs (E1) for a first source of interference and two second inputs (E2) for a second source of interference, wherein the EMC filter (4) further has two first outputs (A1) and two second outputs (A2), wherein the EMC filter (4) has a first EMC filter (12) and a second EMC filter (13), wherein the first EMC filter (12) is arranged between the first inputs (E1) and the first outputs (A1) and the second EMC filter (13) is arranged between the second inputs (E2) and the second outputs (A2), wherein the EMC filter (4) has a housing (11) and at least one component is shared by the first EMC filter (12) and the second EMC filter (13), wherein the at least one shared component is at least a soft magnetic core (16). EMC filter according to Claim 3 , characterized in that the first EMC filter (12) and the second EMC filter (13) are arranged on a common printed circuit board (14).