DE102021209140A1 - Storage choke with modular inner cores for a DC-DC converter, DC-DC converter and vehicle - Google Patents

Abstract

The present invention relates to a storage choke (10) for a multi-phase DC voltage converter (100) for converting a DC input voltage into a DC output voltage for charging a vehicle battery in an electric vehicle or hybrid vehicle, the storage choke (10) having a plurality of coils (12A-C) and a choke core (13) via which the coils (12A-C) are magnetically coupled to one another, the choke core (13) having a plurality of inner cores (14) for mounting the coils (12A-C) and two outer cores (16) between which the inner cores (14) with the coils (12A-C) wound therein are arranged, the inner cores (14) being of modular design with one or more core modules and lined up in a horizontal direction.

Description

The invention relates to a storage choke for a DC-DC converter and the DC-DC converter.

Purely electric vehicles and hybrid vehicles are known in the prior art, which are driven exclusively or in support of one or more electric machines as drive units. In order to supply the electrical machines of such vehicles with electrical energy, the vehicles include electrical energy stores, in particular rechargeable electrical batteries. Batteries are required for high drive power, which provide a correspondingly high DC voltage of, for example, 400V or 800V. Such power batteries are referred to as high-voltage batteries (HV batteries).

The recharging of the HV batteries is currently a challenge, as this requires a charging voltage of several hundred volts, for example 800V, in order to charge the HV batteries effectively without impairing their functionality. However, the charging voltage that conventional charging stations provide for electric vehicles is regularly significantly lower than the desired charging voltage, around 800V. In order to provide such charging voltages, direct voltage converters (DC/DC converters) are used, which are connected between a DC voltage source with an output voltage (e.g. 400V) that is lower than the desired charging voltage (e.g. 800V) and the HV battery to be charged is switched.

A storage choke is present in the DC-DC converter, which is designed to temporarily store energy in the form of magnetic fields. Such a storage choke is off, for example DE102017114900A1 known. The storage choke disclosed there for a multi-phase DC-DC converter has a plurality of coils, each of which is formed by a winding of a copper wire. The windings are each wound around a rod-shaped core. All of the rod-shaped cores form a first area of the storage inductor, which is formed from a first material. Furthermore, the storage inductor has a second region that includes a plurality of outer plates that are formed from a second material. The first material has a higher saturation magnetization and a lower magnetic permeability than the second material.

In this way, a storage choke is realized which is optimized with regard to its differential mode (DM) inductance and common mode (CM) inductance. In particular, the current ripple and thus also the reactive power in the storage choke can be reduced with the above design.

Nevertheless, the known storage choke has the disadvantage that it is complex to manufacture due to its design.

It is an object of the invention to provide a storage choke in which the disadvantages mentioned above are at least partially overcome.

According to the invention, this object is achieved by the storage inductor and the DC/DC converter according to the independent patent claims. Advantageous refinements and developments of the invention emerge from the dependent patent claims.

The storage choke according to the invention is designed to be used in a polyphase DC-DC converter for converting a DC input voltage into a DC output voltage for charging a vehicle battery or a vehicle battery arrangement in an electric vehicle or hybrid vehicle. The storage choke includes several coils and a choke core. The coils are magnetically coupled to one another via the inductor core. The choke core is designed as a combination of two different core types. In particular, the reactor core comprises a plurality of inner cores for mounting the coils and, at the same time, two outer cores between which the inner cores with the coils wound therein are arranged in the vertical direction. According to the invention, the inner cores are of modular design, each with one or more core modules, and lined up in a horizontal direction.

The storage choke according to the invention can be produced easily using modular inner cores. To assemble the storage choke, it is possible to bring the modular inner cores with coils wound into them into the space between the two outer cores, which are preferably designed as core plates. Depending on the number of phases, a corresponding number of inner cores can be combined in the storage choke in a simple manner in order to couple in the corresponding number of coils for the polyphase DC-DC converter. As a result, with the storage choke according to the invention, in contrast to the known storage choke mentioned at the outset, it is not necessary to arrange a large number of cores of different designs individually in the storage choke. In this way, a storage choke is realized in which the assembly is greatly simplified, without additional support structure doors are required. The storage choke is therefore optimized for production.

According to one embodiment, the inner cores each have a carrier and a preferably cylindrical shaft extending out from the carrier, around which the coils are respectively wound. For example, the carrier comprises a floor and two side borders between which the floor is arranged in such a way that an intermediate space is formed for accommodating the coil. In this way, the inner cores can be used as prefabricated components whose geometry is predetermined. In order to optimize the storage choke with regard to the common-mode inductance, the geometry can already be adjusted before the inner cores are installed, so that reliable optimization is ensured. In the case of the known storage choke mentioned at the outset, on the other hand, the various cylindrical and triangular cores must be specifically arranged individually in the storage choke in order to optimize the common-mode inductance of the storage choke, which is error-prone.

According to a further embodiment, the inner cores each have two core modules which are arranged in such a way that their bases face one another and the associated shafts are butt-joined to one another at the ends. This measure enables a simple doubling of the space provided for receiving the coils in the inner cores.

According to another embodiment, the coils in the inner cores are each wound along a vertical axis. The inner cores are preferably arranged such that the shanks extend in the vertical direction. Alternatively, the coils in the inner cores may each be wound along a horizontal axis. The inner cores are preferably arranged such that the shanks extend in a horizontal direction, preferably coaxially. In this case, it is advantageous if adjacent coils have opposite winding directions and/or are subjected to opposite currents.

According to a further embodiment, the inner cores are formed from a first material, with the outer cores being formed from a second material, the first material having a lower magnetic permeability and a comparatively higher saturation magnetization than the second material. A higher magnetic permeability (and at the same time lower saturation magnetization) in the outer cores enables an increase in the differential mode inductance there, which reduces the reactive current in the storage choke. A higher saturation magnetization and at the same time lower magnetic permeability in the inner cores, in which there is a high proportion of DC flux, makes it possible to set a desired common-mode inductance there in order to reduce the ripple current. These advantages mentioned synergize with the advantages resulting from the modular design of the inner cores, to the effect that the optimization of the storage choke that can be achieved by means of a suitable geometry of the inner cores with regard to the differential and common-mode inductances can be reproduced more reliably and more precisely .

The invention also relates to a DC voltage converter for charging a DC voltage source, in particular a HV battery, in an electric vehicle or a hybrid vehicle. The advantages already described in connection with the storage choke according to the invention also result for the DC-DC converter according to the invention.

The invention is explained below by way of example using the embodiments shown in the figures.

• 1 ein schematisches Schaltbild eines mehrphasigen Gleichspannungswandlers;
• 2 eine schematische Darstellung einer Speicherdrossel gemäß einer Ausführungsform für den Gleichspannungswandler aus 1, wobei mehrere Spulen jeweils um eine separate vertikale Achse in einem inneren Kern umfassend zwei Kernmodule gewickelt sind;
• 3 eine schematische Darstellung eines inneren Kerns der Speicherdrossel aus 2;
• 4 eine schematische Darstellung einer Speicherdrossel gemäß einer weiteren Ausführungsform für den Gleichspannungswandler aus 1, wobei die Spulen jeweils um eine separate vertikale Achse in einem inneren Kern umfassend ein Kernmodul gewickelt sind;
• 5 eine schematische Darstellung einer Speicherdrossel gemäß einer weiteren Ausführungsform für den Gleichspannungswandler aus 1, wobei die Spulen jeweils um eine separate horizontale Achse in einem inneren Kern gewickelt sind;
• 6 eine schematische Darstellung einer Speicherdrossel gemäß einer weiteren Ausführungsform für den Gleichspannungswandler aus 1, wobei die Spulen jeweils um eine gemeinsame horizontale Achse in der Speicherdrossel gewickelt sind.

Show it:

• 1 a schematic circuit diagram of a polyphase DC-DC converter;
• 2 a schematic representation of a storage choke according to an embodiment for the DC-DC converter 1 wherein a plurality of coils are each wound about a separate vertical axis in an inner core comprising two core modules;
• 3 a schematic representation of an inner core of the storage inductor 2 ;
• 4 a schematic representation of a storage choke according to a further embodiment for the DC-DC converter 1 wherein the coils are each wound about a separate vertical axis in an inner core comprising a core module;
• 5 a schematic representation of a storage choke according to a further embodiment for the DC-DC converter 1 , the coils each being wound about a separate horizontal axis in an inner core;
• 6 a schematic representation of a storage choke according to a further embodiment for the DC-DC converter 1 , wherein the coils are each wound around a common horizontal axis in the storage inductor.

Identical objects, functional units and comparable components are denoted by the same reference symbols across the figures. These objects, functional units and comparable components are designed to be identical in terms of their technical features, unless the description explicitly or implicitly states otherwise.

1 shows a schematic circuit diagram of a multi-phase DC-DC converter 100 for converting a DC input voltage, which is provided by a DC voltage source 107, into a DC output voltage to a rechargeable battery, in particular a high-voltage (HV) battery 109, in an electric vehicle or charging a hybrid vehicle. The DC-DC converter 100 includes a storage choke 10, which is designed to temporarily store energy in the form of magnetic fluxes. For this purpose, the storage inductor 10 has a plurality of coils 12A-C, three in this case by way of example. By applying a voltage to the windings of the coils 12A-C, a current flow and, associated therewith, a magnetic flux can be generated in the coils 12A-C. The coils 12A-C are each connected between a first capacitor 101 and a half-bridge. The number of half-bridges corresponds to the number of coils 12A-C. Each half-bridge includes a high-side device 102A-C and a low-side device 104A-C. The coils 12A-C are each connected on a side remote from the first capacitor 101 between the respective high-side device 102A-C and the low-side device 104A-C. A second capacitor 106 is provided on the opposite side of the half-bridges from the first capacitor 101 . A first filter 103 for eliminating interference signals in the supplied DC input voltage is connected between the input-side DC voltage source 107 and the polyphase DC voltage converter 100 . In addition, a second filter 105 is connected between the HV battery 109 on the output side and the polyphase DC-DC converter 100, a second filter 105 for eliminating interference signals in the DC output voltage generated.

During operation of the multi-phase DC-DC converter 100, the half-bridges are switched in such a way that a voltage with the same voltage profile, but with a time offset between the coils 12A-C, is applied to the coils 12A-C. In this manner, at certain given times, different voltages will be present across coils 12A-C, at least in part, while at other times the same voltage may be present across coils 12A-C. Due to this time-varying voltage application to the coils 12A-C, a first current (also called reactive current) flowing from the HV battery 109 via the storage choke 10 and finally back to the HV battery 109 is superimposed with a current flowing from the DC voltage source 107 HV battery 109 flowing second current with time-varying shares. The first current or reactive current is due to the differential mode inductance (DM inductance) of the storage inductor 10, which corresponds to the degree of increase (or the first time derivative) of the reactive current. The second current is due to the common-mode inductance (CM inductance) of the storage choke 10, which results from the fact that the dimensions of the storage choke 10 cannot be increased at will. Ripple currents occur due to the CM inductance, which causes power losses. Both the reactive current and the ripple currents should be reduced as far as possible in order to optimize the voltage conversion.

2 shows the storage inductor 10 according to one embodiment in a schematic representation. The storage inductor 10 contains an inductor core 13 via which the coils 12A-C are magnetically coupled to one another. The choke core 13 comprises a plurality of inner cores 14 for attaching the coils 12A-C and two outer cores, which are designed here by way of example as core plates 16 and between which the inner cores 14 with the coils 12A-C wound therein are arranged. As in 2 As shown, the outer cores 16 have a flat, plate-like configuration and extend in a horizontal direction. The three inner cores 14 are arranged in a row between the two outer cores 16 .

The inner cores 14 have a modular design and can in principle each have one or more core modules, the structure of which is shown in 3 shown as an example. The core module has a carrier 15 and a cylindrical shaft 20 extending perpendicularly from the carrier 15 . The carrier 15 comprises a floor 18 and two opposite side borders 22, between which the floor 18 is arranged. The diameter of the cylindrical shank 20 is smaller than the distance between the two side fences 22 so that a gap 24 is formed between the cylindrical shank 20 and the side fences 22 for receiving the respective coils 12A-C. The gap 24 is exposed on a top side opposite the bottom 18 . The side of the respective side limits 22 facing the cylindrical shaft 20 has a circular-arc-shaped profile. The coils 12A-C are each wound around the cylindrical shaft 20 of the associated inner core 14. As shown in FIG.

in the in 2 embodiment shown, each inner core 14 includes two core modules that are joined opposite to one another in such a way that their bottoms 18 face one another and the associated shafts 20 are placed on top of one another in abutting fashion. In this way, the gap 24 is doubled, allowing the coils 12A-C used in this embodiment to have twice as many turns as in the single core module embodiments. In addition, the inner cores 14, along with the coils 12A-C housed therein, are oriented such that the cylindrical shafts 20 extend vertically. Thus, the coils 12A-C are each wound about their associated cylindrical shaft 20 about a vertical axis of their own.

in the in 4 shown embodiment of the storage choke 10 'each inner core 14 contains a single core module. An inner core plate 17 is arranged between the core modules and the upper outer core 16 for better guidance of the common-mode flux component. The inner core plate 17 is thus a common part of the three inner cores 14. Again, the inner cores 14, together with the coils 12A-C housed there, are aligned so that the cylindrical shafts 20 extend vertically. Thus, the coils 12A-C are each wound about their associated cylindrical shaft 20 about a vertical axis of their own.

5 shows a storage choke 10" according to a further embodiment. In this embodiment too, a plurality of inner cores 14 are arranged vertically between two outer cores 16 extending in the horizontal direction. In addition, each inner core 14 likewise comprises a single core module, which in 3 is shown as an example. The difference between this embodiment and the one in 4 The embodiment shown is that the coils 12A-C are each wound about their respective cylindrical shaft 20 about a horizontal axis of their own.

6 shows the storage inductor 10''' according to one embodiment in a schematic representation. Also in this embodiment, a plurality of inner cores 14 are arranged vertically between two outer cores 16 extending in the horizontal direction. In addition, each inner core 14 also includes a single core module that is 3 is shown as an example. The difference between this embodiment and the one in 5 The embodiment shown is that the inner cores 14 are positioned between the outer cores 16 such that the various coils 12A-C are wound around a common horizontal axis. As in 6 As shown, the winding direction of the middle coil 12B is opposite to the winding directions of the other two coils 12A,C. Alternatively, the same winding direction can be used for all three coils 12A-C, with adjacent coils 12A-C being able to be energized in opposite directions.

In order to optimize the DM inductance and CM inductance of the storage choke 10, two different materials can be used for the two components of the choke core 13, the inner cores 14 and the outer cores 16. In the inner cores 14 there is a high proportion of DC flux. A material with high saturation magnetization (e.g. powder core) is suitable here, which at the same time has low magnetic permeability. The DC flux components of the coils 12A-C compensate each other in the outer cores 16, so that there is effectively no DC flux component here. A material with a low saturation magnetization can therefore be used for the outer cores 16 . This enables the use of materials with a high magnetic permeability (e.g. ferrite). DM inductance increases with magnetic permeability. Also, the reactive current can be reduced by increasing the DM inductance.

Reference List

10, 10', 10'', 10'''

storage choke

12A-C

Wash

13

choke core

14

inner core

15

carrier

16

core plate

17

cover plate

18

Floor

20

shaft

22

page limit

24

space

100

polyphase DC-DC converter

101

first capacitor

102A-C

highside facility

103

first filter

104A-C

lowside setup

105

second filter

106

second condenser

107

DC voltage source

109

high-voltage battery

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 102017114900 A1 [0004]

Claims (12)

Storage choke (10) for a polyphase DC voltage converter (100) for converting a DC input voltage into a DC output voltage for charging a vehicle battery in an electric vehicle or hybrid vehicle, the storage choke (10) having a plurality of coils (12A-C) and a choke core (13 ) via which the coils (12A-C) are magnetically coupled to one another, the inductor core (13) comprising a plurality of inner cores (14) for attaching the coils (12A-C) and two outer cores (16) between which the inner cores (14) with the coils (12A-C) wound therein are arranged, the inner cores (14) being modular in design, each with one or more core modules and lined up in a horizontal direction. Storage choke (10) after claim 1 Each core module having a support (15) and a preferably cylindrical shaft (20) extending from the support (15) around which the coils (12A-C) are respectively wound. Storage choke (10) after claim 2 wherein the support (15) comprises a bottom (18) and two side borders (22) between which the bottom (18) is arranged such that an intermediate space (24) for receiving the coil (12A-C) is formed. Storage choke (10) after claim 2 or 3 , wherein the inner cores (14) each have two core modules which are joined together in opposite directions in such a way that their bottoms (18) face one another and the associated shafts (20) are placed end to end on top of one another. Storage choke (10) according to one of Claims 1 until 4 , wherein the core modules are each formed in one piece. Storage choke (10) according to one of Claims 1 until 5 wherein the coils (12A-C) in the inner cores (14) are each wound along a vertical axis. Storage choke (10) according to one of Claims 1 until 5 wherein the coils (12A-C) in the inner cores (14) are each wound along a horizontal axis. Storage choke (10) after claim 7 , the coils (12A-C) being wound coaxially. Storage choke (10) according to one of Claims 1 until 8th , wherein adjacent coils (12A-C) have opposite winding directions and/or are subjected to opposite currents. Storage choke (10) according to one of Claims 1 until 9 wherein the inner cores (14) are formed from a first material, wherein the outer cores (16) are formed from a second material, the first material having a lower magnetic permeability and a relatively higher saturation magnetization than the second material. Multi-phase DC-DC converter (100) for converting a DC input voltage into a DC output voltage for charging a vehicle battery in an electric vehicle or hybrid vehicle, comprising a storage choke according to one of Claims 1 until 10 . Vehicle, in particular electric vehicle or hybrid vehicle, comprising a multi-phase DC-DC converter (100). claim 11 .

Images