EP4197014A1

EP4197014A1 - Coupled pfc choke

Info

Publication number: EP4197014A1
Application number: EP21762599.5A
Authority: EP
Inventors: Tim KARCHER
Original assignee: Innolectric AG
Current assignee: Innolectric AG
Priority date: 2020-08-12
Filing date: 2021-08-11
Publication date: 2023-06-21
Also published as: DE102020121245A1; WO2022033633A1

Abstract

The invention relates to a charger (OBC) (1) for an electric motor vehicle (2), comprising a housing having at least one electric input terminal (7), at least one output terminal (8), and power electronics (15) that are arranged in the housing and include at least one voltage converter and at least two PFC chokes (12), each PFC choke (12) being formed by a U-shaped wound core (16), the wound cores (16) being placed directly next to each other and the openings (19) in the U-shape being oriented in the same direction.

Description

Coupled PFC choke

The present invention relates to on-board charging electronics according to the features in the preamble of FIG.

It is known from the prior art to use electrical energy to move motor vehicles. Such motor vehicles are driven purely electrically as an electric vehicle. However, there are also hybrid variants in which energy is also generated with an internal combustion engine or a fuel cell. What both vehicles have in common is that the electrical energy is stored in a traction battery, also referred to below as a rechargeable battery, accumulator or battery.

This traction battery is charged when the electric vehicle is idle by connecting it to an external voltage source.

Depending on the local conditions and also depending on the country in which the electric vehicle is to be charged, there are different ones Connection options and supply voltages for carrying out the charging process are available. Usually the supply voltage is 100V - 500V with a frequency of 50 - 60 Hz.

For this purpose, power electronics are used, which transform the different supply voltages to a charging voltage, so that the traction battery in the electric vehicle can be charged.

So that the electric vehicle can now be used as flexibly as possible for different supply voltages, there is power electronics with charging communication in the motor vehicle, which is also referred to as an on-board charger (OBC). Such on-board charging electronics can generally be connected to single-phase networks (typically PL-i and N conductors) or three-phase networks (PL-i — PL ₂ - PL ₃ conductors, with/without N conductor) operate. The OBC essentially transforms the 50 Hz sinusoidal AC voltage (supply voltage) into a DC voltage. The OBC can also create potential-free conditions between the vehicle and the supply network with the help of an integrated transformer.

So that the 50 Hz AC voltage (supply voltage) can be converted into a DC voltage (charging voltage), active front ends (AFE) or power factor correction (PFC) are used in the prior art. PFCs are used when the flow of energy is only directed from the supply voltage to the load. So-called bidirectional PFCs are also known. Conversely, if the battery is discharged in order to feed the battery voltage into the supply network, this is referred to as an AFE, which can also be referred to as a bidirectional PFC.

It is known from the prior art that a PFC choke is formed from an inductance, and therefore a wound coil. Such a coil also has a winding core.

The object of the present invention is to show, based on the prior art, on-board charging electronics that have a reduced weight and a has lower power loss with simultaneously increased effectiveness and improved voltage conversion.

The aforementioned object is achieved with an on-board charging device for an electric vehicle according to the features in the preamble of claim 1.

Advantageous design variants are part of the dependent claims.

An on-board charging device is therefore an on-board charger. This is used in an electric motor vehicle or a hybrid vehicle, generally referred to below as an electric motor vehicle. The on-board charging device is installed in the electric car. For this purpose, it has a housing. The housing has at least one electrical input port and at least one electrical output port. Power electronics are arranged in the housing. The power electronics include at least one voltage converter and at least two PFC chokes. The PFC chokes are designed as respective inductors.

Each PFC choke is formed by a coil on a U-shaped core. According to the invention, the openings of the U-shape are arranged pointing in the same direction.

More than two, in particular more than three, particularly preferably six, U-shaped winding cores can be arranged. At least one coil is then wound onto each winding core to form an inductance. The coil can be wound up individually, but it can also be wound onto a respective web of the U-shape, ie two coils on one winding core.

According to the invention, the respective U-shaped winding cores are arranged directly next to one another. In this context, however, directly next to one another means that they are arranged electrically separated from one another, for example by means of an air gap and/or an insulating material between the winding cores. With regard to the most compact possible design, the air gap is kept as small as possible. In addition, an electrical insulating material can be arranged in the air gap. Each individual inductance is thus in the Power electronics associated with a conductor. Each individual inductance is preferably assigned to an intermediate circuit. Each inductance is particularly preferably assigned to a conductor in the intermediate circuit.

By arranging the U-shaped winding cores in such a way that the opening of the U-shape of each winding core is oriented in the same direction, a particularly compact design and thus a small size of the on-board charging device can be achieved.

A further significant advantage is that the winding initially generates a magnetic field in the winding core, in particular a direction of magnetic flow, when a voltage is applied. In the area of the valley of the U-shape of two adjacent inductances, the magnetic fields are formed in opposite directions, so that the two magnetic fields compensate or neutralize each other, which occurs at least partially, in particular almost completely. The power loss generated by the magnetic flux and the associated heat dissipation are thus significantly minimized. This increases the efficiency of the on-board charging device. At the same time, further cooling measures, for example liquid cooling or ventilation cooling, can be reduced since less heat energy is generated overall due to power loss.

In turn, the design of the on-board charging electronics can also be smaller because, for example, heat sinks or the like can be dimensioned smaller or are no longer necessary.

The U-shaped winding cores are thus physically arranged in series, but are electrically separated or insulated from one another. The U-shaped winding core which is arranged last in this physical row thus has a U-shaped opening which points into the "empty". A rod is particularly preferably arranged here, for example a flat rod. This bar then ensures that in particular the magnetic flux in this last U-shaped winding core is conducted through the flat bar. Another important advantage is that a U-shaped winding core is used to form a PFC choke using an inductor. For this purpose, the coil wound onto the winding core can be designed in such a way that there are two coils which are electrically connected to one another and are wound onto the webs of the U-shape.

In particular, an HF litz wire is used as the conductor or litz wire for producing the winding. HF stands for high frequency. With an HF litz wire, skin losses are reduced. Such an HF litz wire consists of many thin wires, each wire having a diameter of about 0.05 mm. The wires are preferably twisted into a bundle. The bundle itself then has a diameter of 1 - 3 mm. The choke is preferably wound from such a bundle.

The U-shaped winding core itself has a cross section that is round, but preferably rectangular. The cross-sectional area of the winding core is particularly preferably from 100 mm ² to 1000 mm ² . For example, this can be realized with a rectangular cross section of 10×10 mm up to 32×32 mm.

The on-board charger is particularly preferably connected to a three-phase network. Here, three conductors are designed as each phase. A neutral conductor is also provided. A protective conductor is provided as an option. At least one PFC choke is particularly preferably assigned to each phase. A PFC choke can also be assigned to the neutral conductor. An intermediate circuit with a capacitor is particularly preferably assigned to each phase. In this case, each intermediate circuit is also connected to the neutral conductor. A PFC choke is then particularly preferably arranged in each phase and in each case to the neutral conductor, so that a total of six PFC chokes are used in a preferred arrangement.

Further advantages, features and properties are shown in the following figures. These serve to make the invention easier to understand. Show it:

Figure 1 is a block diagram of an on-board charger in one

electric vehicle, Figure 2 shows the power electronics in an on-board charger with an intermediate circuit,

Figure 3 the power electronics with three intermediate circuits,

FIG. 4 shows an arrangement of the PFC chokes according to the prior art,

FIG. 5 shows an arrangement of the PFC choke according to the invention,

FIG. 6 shows an arrangement according to the invention of the PFC chokes with three intermediate circuits in a three-phase network.

In the figures, the same reference numbers are used for the same or similar components, even if a repeated description is omitted for reasons of simplification.

FIG. 1 shows the arrangement of an on-board charging device 1 according to the invention in an electric motor vehicle 2 . The external charging socket 4 provides a supply voltage 6 ready. The on-board socket 3 is electrically connected to the on-board charging device 1 . For this purpose, the on-board charging device 1 has at least one electrical input connection 7 . Furthermore, the on-board charging device 1 has an electrical output connection 8 which is coupled to a traction battery 9 of the electric motor vehicle 2 . Further electrical input connections or output connections 10 can be present, for example an input connection of the vehicle battery, in particular with regard to a communication connected thereto. In addition, a communication network of the electric motor vehicle 2, for example a CAN bus, can also be connected. This can also be cooling connections.

A mains filter 11 is then arranged in particular in the on-board charging device 1, for example in the form of an EMI filter. This is then followed by a PFC choke 12, in turn followed by a voltage converter or transformer 13 for converting the supply voltage 6 into a charging voltage and a optional rectifier 14, which is then electrically coupled to the actual traction battery 9.

Figure 2 shows the power electronics 15 within the on-board charging device 1. A three-phase network is connected here, based on a first phase PLi, a second phase PL ₂ , a third phase PL ₃ and a neutral conductor N. It can optionally be a non shown protective conductor must be present. A PFC choke 12 is coupled to each phase. In turn, these are electrically connected to the transformer 13 via a respective switch Si, S ₂ , S ₃ . The switches can be formed by transistors (MOS, SiC-MOS, IGBTs or thyristors), for example. Alternatively or additionally, the switches can also be formed by diodes or mixed forms of the aforementioned components. Also provided is a capacitor K connected in parallel.

FIG. ₃ shows a structure analogous to FIG. 2. Here, however, an intermediate circuit is formed for each phase _PLi , PL2, PL3. From a technical point of view, each intermediate circuit represents a voltage source that must not be directly connected to one another. Six PFC chokes 12 are arranged to limit the current. Each PFC choke 12 is thus formed by an inductor Li to L ₆ . These are connected via switches Si to Sß with the respective transformer 13 and an optional rectifier 14 downstream of this. The rectifiers 14 are coupled to the traction battery 9 .

FIG. 4 now shows a structure of a respective PFC choke 12 in the form of an inductance, as is known from the prior art. For this purpose, two winding cores 16 are provided, which are arranged in opposite directions towards one another. The electrical connections A1-B1 and A6-B6 are shown as examples in FIG. Each winding 17 comprises a valley area 21 of the egg-shaped winding core 16. An air gap 23 is arranged between the two cores.

FIG. 5 now shows the approach according to the invention. A respective PFC choke 12 is formed by a U-shaped winding core 16. The windings 17 of an inductance L1 to _L6 are formed in particular on the two opposite webs 18 of the respective U-shaped winding core 16. The respective opening 19 of the U-shaped winding core 16 is arranged oriented in the same direction. Thus, the U-shaped hubs 16 are physically arranged in series with one another. The openings 19 are arranged pointing oriented in a same direction. In the example of FIG. 5, this means arranged pointing to the right in relation to the image plane. A magnetic flux 20 arising in each case from two adjacent PFC chokes 12 is thus neutralized in a valley region 21 of the PFC choke 12. As a result, the power loss can be reduced. There is thus a compensation in this area of the magnetic flux.

A rod 22 is arranged on the last PFC choke 12 on the right, referred to in the image plane, in order to conduct the magnetic flux 20 here as well. Overall, this results in a significantly more compact design of the individual inductances Li to Le in relation to one another. In the air gap 23 between two adjacent inductors L 1 to L ₆ , an insulating material (not shown) can optionally be arranged. The size of the air gap (distance between the winding cores) and the arrangement/selection of the insulating material can be used to adjust the inductance of the PFC choke on the left in relation to the image plane. The air gap preferably has a size of 100 μm to 3 mm.

FIG. 6 shows an arrangement with six PFC chokes 12 or six inductances Li to L _6I which the present invention applies to a circuit arrangement with three intermediate circuits according to FIG.

Shown are the six U-shaped winding cores 16 physically arranged in a row with one another, the openings 19 of which are each oriented in the same direction, shown to the right in relation to the plane of the drawing. A rod 22 is arranged at the end. The rod preferably has the same cross-sectional area compared to the winding cores 16.

Each of the two inductances Li to L ₆ arranged in an intermediate circuit relative to one another are arranged electrically in series in a respective conductor according to FIG. This results in a magnetic flux 20 running in the same orientation in the winding core 16, such that a compensation 24 of the magnetic flux 20 results in a valley region 21 of at least one inductance Li to L ₆ . The circular magnetic flux in FIG. 6 corresponds to a uniform (e.g.: positive) current flow from top to bottom (relative to the image plane) for all Li to Le, so that the flux is compensated in each case in area 24 and not added. If you now look at Figure 3, due to the power structure, with a positive current flow from A1 to B1, the current from B2 to A2 is positive. For this reason, the connections Ax and Bx in FIG. 6 must be swapped over alternately at the top and bottom so that the compensation 24 is achieved.

However, the sense of winding between Li, L ₃ , L ₅ and L ₂ , L ₄ , L ₆ could also be exchanged, then all A connections would have to be switched, e.g. For example, be at the top and all B connections at the bottom.

Reference sign:

1 - onboard charger

2 - electric vehicle

3 - on-board socket

4 - external charging socket

5 - charging cable

6 - supply voltage

7 - electrical input connector

8 - electrical output connector

9 - traction battery

10 - further electrical input connections or output connections

11 - mains filter

12 - PFC choke

13 - transformer

14 - rectifier

15 - power electronics

16 - winding core

17 - winding

18 - Jetty

19 - opening

20 - magnetic flux

21 - valley area

22 - staff

23 - air gap

24 - Compensation

K - capacitor

Li - inductance

L ₂ - inductance

L ₃ - inductance

L ₄ - inductance

L ₅ - inductance l_6 - inductance

N - neutral wire

PE - protective conductor

PLi - phase

PL ₂ - phase

PL ₃ - phase

51 . counter

5 ₂ . counter

53- switch

54 switch

55 switch

Sweet switch

Claims

On-board charging device (OBC) (1) for an electric motor vehicle (2), having a housing with at least one electrical input connection (7) and at least one output connection (8) and power electronics (15) arranged in the housing, which have at least one voltage converter and at least has two PFC chokes (12), characterized in that each PFC choke (12) is formed by a U-shaped winding core (16), the winding cores (16) being arranged directly next to one another, the openings (19) of the U Shape are arranged pointing oriented in the same direction. On-board loading device (1) according to Claim 1, characterized in that more than two, in particular more than three and preferably six U-shaped winding cores (16) are physically arranged in series. On-board loading device (1) according to Claim 1 or 2, characterized in that a rod (22), in particular a flat rod, is arranged on the last U-shaped winding core (16). On-board loading device (1) according to the preceding claim, characterized in that the flat bar (22) has a cross-section which corresponds to the U-shaped winding core (16), in particular in the valley of the U-shape. On-board charging device (1) according to one of Claims 1 to 4, characterized in that a magnetic flux (20) is generated in each PFC choke (12), the magnetic fluxes (20) of two adjacent PFC chokes (12) being in one At least partially, in particular completely neutralize the valley of the U-shape. On-board charging device (1) according to one of Claims 1 to 5, characterized in that the U-shape has two legs, the winding (17) being formed only in the region of one leg, which is preferred both legs are each provided with a winding (17), the two windings (17) being electrically connected. On-board charging device (1) according to one of Claims 1 to 6, characterized in that at least two conductors, a phase (PLi, PL ₂ , PL ₃ ) and a neutral conductor (N), preferably three phases (PL-i, PL ₂ , PL ₃ ) are arranged on the side of the input terminals (10). On-board charging device (1) according to one of claims 1 to 7, characterized in that each phase (PL-i, PL ₂ , PL ₃ ) is assigned a respective PFC choke (12) and/or that the neutral conductor (N) has a PFC Choke (12) is assigned. On-board charging device (1) according to the preceding claim, characterized in that three separate intermediate circuits are arranged in the charging device (1), a phase (PLi, PL ₂ , PL ₃ ) and the neutral conductor (N) being connected in each intermediate circuit, preferably via one switch each (Si to Sß), and each phase (PL-i, PL ₂ , PL ₃ ) and each connection of the neutral conductor (N) is assigned a PFC choke (12) to the respective phase, with particularly preferably in connected in parallel in each intermediate circuit in the capacitor. On-board charging device (1) according to one of Claims 1 to 9, characterized in that a sinusoidal voltage (supply voltage) is converted into a DC voltage (charging voltage).