On-board charger

Abstract

The invention relates to an on-board charger (OBC) for a motor vehicle, comprising: input connections (3), via which the on-board charger (OBC) is connectable to an AC voltage source, and output connections (6), via which the on-board charger (OBC) is connectable to an energy store (2); and a control unit (1), which is designed to control the on-board charger (OBC) such that the on-board charger (OBC), when the AC voltage source is connected to the input connections and the energy store (2) is connected to the output connections, in a charging process, rectifies a charging alternating current supplied from the AC voltage source and supplies the rectified charging current via an intermediate circuit store (71, 72) to the electrical energy store (2) for charging, wherein the control unit (1) is designed to receive a load change signal (S) and, after receiving the load change signal (S), in the charging process, to generate a load change current flow at least from the intermediate circuit store (70, 71) into the AC voltage source.

Description

[0001] 202401297

[0002] 1

[0003] Description

[0004] On-board charging device

[0005] The invention relates to an on-board charging device for a motor vehicle. Fully electric and hybrid motor vehicles are typically charged by a user connecting them to the public power grid. This is done either by connecting to public charging stations or by connecting to private electrical outlets.

[0006] Due to the increasing number of fully electric and hybrid vehicles, the public electrical grid is increasingly burdened at different times by various combinations of inductive, capacitive and resistive loads.

[0007] Operators of the public electrical grid try to counteract unfavorable situations and take measures to change the nature of the load on the grid, in particular to reduce the reactive power required.

[0008] Against this background, the object of the invention is to provide a solution enabling fully electric and hybrid vehicles to contribute to reducing the load on the public electrical grid. At the very least, the object of the invention is to provide an alternative to the prior art.

[0009] This problem(s) is solved by an on-board charging device (OBC) according to claim 1. Preferred embodiments are the subject of the dependent claims.

[0010] An on-board charging device for a motor vehicle according to the invention includes:

[0011] Input terminals via which the on-board charging device can be connected to an AC voltage source, and output terminals via which the on-board charging device can be connected to an energy storage device of the vehicle, and a control unit which is configured to control the on-board charging device in such a way that the on-board charging device is connected to the input terminals 202401297

[0012] 2 connected AC voltage source and, with an energy storage device connected to the output terminals, rectifies a charging alternating current supplied by the AC voltage source in a charging process and supplies the rectified charging current to the electrical energy storage device for charging via an intermediate circuit storage device, wherein the control unit is configured to receive a load change signal and, after receiving the load change signal, to generate a load change current flow at least from the intermediate circuit storage device into the AC voltage source in the charging process.

[0013] The on-board charging device preferably includes a plurality of charging phases, in particular three charging phases, and preferably a neutral conductor. The input terminals are located in a charging socket into which a charging plug of the AC voltage source, for example an AC charging station, is inserted during the charging process.

[0014] Depending on the configuration of the AC power source – for example, country-specific – the charging plug applies an AC voltage to one or more of the charging phases. For example, there are AC power sources, especially AC charging stations, that carry out the charging process using either a single-phase or three-phase power.

[0015] The energy storage device of the motor vehicle is, for example, an electric solid-state battery or an electrochemical battery, in particular a high-voltage battery, which supplies a drive unit of the motor vehicle during ferry operation.

[0016] The control unit is configured to receive the load change signal. The load change signal is an external signal, typically sent by the operator of the AC power source or the operator of the public power grid, which indicates that the vehicle should change the load it represents for the AC power source / grid. For example, the vehicle constitutes a capacitive load, and the load change signal indicates that the vehicle should reduce or increase the capacitive component. This load change is achieved, in particular, by generating the load change current flow. 202401297

[0017] 3

[0018] Preferably, the on-board charging device includes a switchable power factor correction rectifier circuit with a plurality of switches; wherein the control unit is configured to control the switches during the charging process after receiving the load change signal in such a way that the load change current flow from at least the intermediate circuit storage into the AC voltage source is generated.

[0019] The power factor correction rectifier circuit is specifically designed to rectify the AC charging current supplied by the AC voltage source during the charging process, in order to supply the rectified charging current to the intermediate circuit storage and the energy storage device. The intermediate circuit storage is preferably at least one intermediate circuit capacitor. The plurality of switches is preferably a plurality of power transistors, such as field-effect transistors (MOSFETs) or IGBTs.

[0020] The switchable power factor correction rectifier circuit is, for example, a three-phase "T-Type Vienna Rectifier" with three bridge branches, each containing two power switches, specifically two power transistors. A center tap between the power switches is connected to each charging phase.

[0021] Furthermore, the intermediate circuit of the three-phase “T-Type Vienna Rectifier” contains two capacitors, wherein a center tap, preferably located at the potential of the neutral conductor and situated between the capacitors, is connected to the center taps of the bridge branches via at least one switching device.

[0022] The control unit is connected to the respective switches for controlling the power factor correction rectifier circuit. The control unit is configured to receive the load change signal, for example, via a radio transmitter. Alternatively, the control unit can receive the load change signal via the AC voltage source or via the charging phases and includes a demodulation circuit for this purpose, to demodulate and thus receive the load change signal modulated onto the charging phases. 202401297

[0023] 4

[0024] Preferably, the switchable power factor correction rectifier circuit of the on-board charging device includes a plurality of diodes, to each of which one of the plurality of switches is connected in parallel; wherein the control unit is configured to control the switches during the charging process after receiving the load change signal in such a way that the load change current flow from at least the intermediate circuit storage into the AC voltage source is generated.

[0025] In this embodiment, the switchable power factor correction rectifier circuit is, for example, a three-phase "Vienna Rectifier" with three bridge branches, in which the diodes are located as physical components. The switches are connected in parallel to the respective diodes, with the control unit activating these switches when the load-changing current flow needs to be generated.

[0026] Furthermore, the "Vienna Rectifier" is identical in construction to the "T-type Vienna Rectifier," as explained above. It should be noted here that by adding the switches to a "Vienna Rectifier," a widely used circuit can be easily and cost-effectively adapted for the invention.

[0027] The switchable power factor correction rectifier circuit, in particular the “Vienna Rectifier” or the “T-type Vienna Rectifier”, are boost converters and preferably include inductors / coils in the charging phases.

[0028] The on-board charging device can operate with or without a neutral conductor.

[0029] The power factor correction rectifier circuit can be a unidirectional or bidirectional power factor correction rectifier circuit which, when an energy storage device is connected, allows no current flow or a current flow from the energy storage device to a load connected to the input terminals after the charging process.

[0030] The control unit is configured in the unidirectional design of the power factor correction rectifier circuit to generate the load change current flow exclusively from the intermediate circuit storage to the AC voltage source, and in the bidirectional design of the power factor correction rectifier circuit to

[0031] 5

[0032] To generate load-changing current flow from the intermediate circuit storage and / or the energy storage into the AC voltage source.

[0033] The invention can therefore be applied to both embodiments of the power factor correction rectifier circuit.

[0034] The control unit is preferably configured to actuate the switches in a pulsed manner to generate the load-changing current flow.

[0035] The control unit is particularly preferably configured to generate the load-changing current flow by changing the power factor through control of the switchable power factor correction rectifier circuit. In this context, the control unit is configured to change the power factor in the positive or negative range and / or to change the power factor such that its sign changes.

[0036] Preferably, the control unit is configured to vary the power factor between cos(phi) = 0.9 ... , 1 , ... -0.9. The AC voltage(s) of the AC voltage source are sinusoidal. If the control unit does not receive a load change signal, its default setting is preferably such that the power factor is close to 1.

[0037] In general terms, the on-board charging device according to the invention is designed to change the type of load that the motor vehicle equipped with it presents to the AC voltage source or the public electrical grid, in particular to change the capacitive and / or inductive component, for example to increase, decrease, and / or to change the type of load from a capacitive load to an inductive load and vice versa.

[0038] A preferred embodiment of the invention is explained below with reference to Figure 1, wherein Figure 1 shows an on-board charging device according to the invention.

[0039] Figure 1 shows an on-board charging device (OBC) according to a preferred embodiment of the invention.

[0040] The on-board charging device (OBC) is intended to be installed in a fully electric or hybrid powered motor vehicle 4, such as a 202401297

[0041] 6. A fully electric or hybrid-powered automobile, installed. This installation state is shown in Figure 1.

[0042] The on-board charging device (OBC) serves to recharge an electrical energy storage device 2 of the motor vehicle, which is a DC energy storage device, after it has been discharged. The energy storage device 2 shown is, in particular, a high-voltage battery that supplies an electric drive unit of the motor vehicle 4 and preferably an on-board electrical system of the motor vehicle with electrical energy. The energy storage device 2 is, in particular, a solid-state battery or an electrochemical battery.

[0043] The on-board charging device (OBC) includes as its essential components a control unit 1 and a power factor correction rectifier circuit 5 with an intermediate circuit constructed from capacitors 71 and 72. The power factor correction rectifier circuit 5 has input terminals for connection to an AC voltage source and output terminals 6, which are intended to be connected to a rectifier 8.

[0044] The control unit 1 preferably takes over the entire control of the on-board charging device OBC, but at least the function according to the invention of changing the type of load of the motor vehicle 4, which will be explained in more detail below.

[0045] The input connections are preferably located in a charging socket 3, which is accessible on an outer surface of the motor vehicle 4.

[0046] The on-board charging device (OBC) is, as intended, located between the energy storage device 2 and an AC charging station (AC voltage source), which supplies the electrical energy required for charging. In this context, the on-board charging device (OBC) is connected to the AC charging station via the charging socket 3 and to the energy storage device 2 via the rectifier 8 through the output terminals 6.

[0047] The AC charging station is part of a public electrical grid. 202401297

[0048] 7

[0049] The power factor correction rectifier circuit 5, which is controlled by the control unit 1, is in particular a unidirectional "Vienna Rectifier". It can only be operated in such a way that the energy storage device 2 is charged when an AC charging station is connected. A reverse operation, called "vehicle-to-load", whereby the energy storage device 2 supplies a load connected to the charging socket 3, is not possible. The invention is not limited to the unidirectional configuration.

[0050] The dashed line shown in Figure 1 schematically indicates the outer surface of the vehicle 4. The charging socket 3 is located on the outer surface of the vehicle 4, so that a charging plug (not shown) of the AC charging station can be inserted into the charging socket 3 to charge the vehicle 4 or the energy storage device 2 and be connected to the on-board charging device (OBC).

[0051] The on-board charging device (OBC) includes three charging phases L1, L2, L3 and preferably a neutral conductor N, which can be contacted via the charging socket 3 with the charging plug of the AC charging station.

[0052] The power factor correction rectifier circuit 5 is the three-phase unidirectional "Vienna Rectifier" with a bridge configuration comprising three bridge arms 50, 51, 52. Each of the bridge arms 50, 51, 52 contains one high-side diode 50a, 51a, 52a and one low-side diode 50b, 51b, 52b.

[0053] The switches 53a, b that bridge these diodes will be discussed further below. At this point, however, it should be mentioned that the diodes 50a, 51a, 52a, 50b, 51b, 52b mentioned are specific components of the "Vienna Rectifier" – and not body diodes of switches 53a, b.

[0054] The charging phases L1, L2, L3 are each connected to a corresponding bridge branch 50, 51, 52 at a center tap between the respective high-side diode 50a, 51a, 52a and the corresponding low-side diode 50b, 51b, 52b. An inductor or coil 9 is preferably located between the respective center taps and the charging socket 3 in each of the charging phases L1, L2, L3.

[0055] As mentioned, the intermediate circuit consists of two capacitors 71 and 72 connected in series and in parallel to the bridge branches 50, 51, and 52. 202401297

[0056] 8

[0057] Additionally, each of the center taps located between diodes 50a, 51a, 52a, 50b, 51b, 52b is connected via a switching device QL1, QL2, QL3 to a center tap of the intermediate circuit located between capacitors 71, 72. The center tap of the intermediate circuit is at the potential of, or connected to, the neutral conductor N.

[0058] The control unit 1 is preferably configured to control the components described above and preferably the rectifier 8, and thus to carry out a charging process to charge the energy storage device 2.

[0059] When the charging plug of the AC charging station is inserted into the charging socket 3 and the supplied AC voltages are present at the charging phases L1, L2, L3, the control unit 1 controls the switching devices QL1, QL2, QL3 in a manner known per se, which results in the AC voltages and charging currents supplied by the AC charging station being rectified into a DC charging voltage or a rectified charging current.

[0060] The rectified charging current charges the intermediate circuit capacitors 71, 72, with an output voltage of the intermediate circuit being applied to the DC-DC converter 8. The control unit 1 controls the DC-DC converter 8 such that it charges the energy storage device 2.

[0061] The switching operations of the switching devices QL1, QL2, QL3, in interaction with the coils 9 and the diodes 50a, 51a, 52a, 50b, 51b, 52b, result in a boost conversion. In this context, the diodes 50a, 51a, 52a, 50b, 51b, 52b are also called boost diodes. This boost conversion function is merely preferred.

[0062] The control of the switching devices QL1, QL2, QL3 by the control unit 1 results not only in rectification and the preferred step-up conversion, but also in power factor correction. The resulting power factor, cos(phi), is close to 1, with this value preferably corresponding to the standard setting of the control unit 1.

[0063] The AC charging station is part of the public power grid, to which various consumers are connected at different times. These various consumers represent resistive, inductive, or capacitive loads for the public power grid. 202401297

[0064] 9

[0065] For example, if too many capacitive or inductive loads are connected to the public power grid, unfavorable load conditions arise in which the reactive power to be generated is high. In these situations, the operators of the public power grid take measures to reduce the proportion of reactive power.

[0066] To contribute to this, the known unidirectional “Vienna Rectifier” is further developed according to the invention, the further development consisting in that each of the diodes 50a, 51a, 52a, 50b, 51b, 52b is bridged by a respective switch 53a, b.

[0067] Switches 53a, b are preferably IGBTs or power field-effect transistors (MOSFETs).

[0068] The control unit 1 is configured to control these switches 53a, b during a respective charging process and thus bridge the corresponding diodes 50a, 51a, 52a, 50b, 51b, 52b.

[0069] This bridging allows a load-changing current flow from the intermediate circuit or the capacitors 71, 72 into the AC charging station and the public power grid during the charging process.

[0070] This load-changing current flow causes the resulting power factor to change, and the vehicle 4 then represents a different type of load for the public power grid. For example, the load-changing current flow can be adjusted and the power factor changed so that the vehicle 4 represents a more capacitive or more inductive load for the public power grid. Preferably, the control unit 1 is configured to adjust the load-changing current flow so that the power factor is between cos(phi) 0.9 and -0.9. The switches 53a, b are controlled by the control unit 1 depending on a received load-changing signal S.

[0071] The control unit 1 is preferably configured to receive this load change signal S wirelessly, e.g., via a mobile network, and to control switches 53a and b based on this signal. For this reception, the control unit 1 preferably includes a radio unit. 202401297

[0072] 10

[0073] Alternatively, control unit 1 can be configured to receive the load change signal S as a signal modulated onto one of the charging phases L1, L2, L3 and therefore has a corresponding demodulation unit. Control unit 1 preferably controls switches 53a, b in a clocked manner.

[0074] The invention has been described above with reference to a unidirectional "Vienna Rectifier" extended by switches 53a, b. This extension of the unidirectional "Vienna Rectifier" is cost-effective. The invention is not limited to this. For example, a bidirectional "T-Type Vienna Rectifier" can also be used within the scope of the invention. In this case, the structure shown in Figure 1 is modified by omitting the diodes and using only appropriately dimensioned switches, in particular transistors, in the bridge branches.

[0075] The statements preceding the description of the figures apply equally to the description of the preferred embodiment and vice versa.

Claims

202401297 11 Patent claims 1. An on-board charging device (OBC) for a motor vehicle comprising: input terminals (3) via which the on-board charging device (OBC) can be connected to an AC voltage source, and output terminals (6) via which the on-board charging device (OBC) can be connected to an energy storage device (2), and a control unit (1) configured to control the on-board charging device (OBC) such that, with an AC voltage source connected to the input terminals and an energy storage device (2) connected to the output terminals, the on-board charging device (OBC) rectifies an AC charging current supplied by the AC voltage source in a charging process and supplies the rectified charging current to the electrical energy storage device (2) for charging via an intermediate circuit storage device (71, 72), wherein the control unit (1) is configuredto receive a load change signal (S) and, after receiving the load change signal (S), to generate a load change current flow during the charging process, at least from the intermediate circuit storage (70, 71) into the AC voltage source.

2. On-board charging device (OBC) according to claim 1, wherein the on-board charging device (OBC) comprises a switchable power factor correction rectifier circuit (5) with a plurality of switches (53a, b); and the control unit (1) is configured to control the switches (53a, b) during the charging process after receiving the load change signal (S) such that the load change current flow from at least the intermediate circuit storage (70, 71) into the AC voltage source is generated.

3. On-board charging device (OBC) according to claim 2, wherein the switchable power factor correction rectifier circuit (5) of the on-board charging device (OBC) comprises a plurality of diodes (50a, b; 51a, b; 52a, b) to which one of the plurality of switches (53a, b) is connected in parallel; and the control unit (1 ) is configured to control the switches (53a, b) during the charging process after receiving the load change signal (S) in such a way that the load change current flow from at least the intermediate circuit storage (70, 71 ) into the AC voltage source is generated. 202401297 12 4. On-board charging device (OBC) according to claim 3, wherein the power factor correction rectifier circuit (5) is a unidirectional power factor correction rectifier circuit (5) which, when the energy storage device (2) is connected, does not allow any current flow from the energy storage device (2) to a load connected to the input terminals (3) after the charging process; and the control unit (1) is configured to generate the load change current flow exclusively from the intermediate circuit storage device (70, 71) to the AC voltage source.

5. On-board charging device (OBC) according to claim 2, wherein the power factor correction rectifier circuit (5) is a bidirectional power factor correction rectifier circuit (5) which, when the energy storage device (2) is connected, allows a current flow from the energy storage device (2) to a load connected to the input terminals (3) after the charging process; and the control unit (1) is configured to generate the load change current flow from the intermediate circuit storage device (70, 71) and / or the energy storage device (2) to the AC voltage source.

6. On-board charging device (OBC) according to any one of claims 2 to 5, wherein the control unit (1 ) is configured to control the switches (53a, b) in a pulsed manner.

7. On-board charging device (OBC) according to any one of claims 1 to 6, wherein the control unit (1) is configured to generate the load change current flow by changing the power factor by controlling the switchable power factor correction rectifier circuit (5).

8. On-board charging device (OBC) according to claim 7, wherein the control unit (1) is configured to change the power factor in the positive range or in the negative range and / or to change the power factor such that the sign of the power factor changes.

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