Method for operating charger, charger, energy system and motor vehicle

Abstract

The invention relates to a method for operating a charger (1) for a motor vehicle, in particular an on-board charger for a motor vehicle, the charger (1) having a multi-phase input connection (3) for connection to a multi-phase supply network connection (4) of an in particular stationary supply network, and a voltage converter (5), the voltage converter (5) has at least one intermediate circuit (13) with at least one intermediate circuit capacitor (14, 15). According to the invention, after the input connection (3) is connected to the supply network connection (4), a first intermediate circuit voltage of the intermediate circuit (13) is detected by means of a voltage sensor (V13) of the intermediate circuit (13) before the intermediate circuit (13) is connected to a neutral phase (N) of the input connection (3) by means of an actuatable switching element (S4), and detecting a second intermediate circuit voltage of the intermediate circuit (13) after the intermediate circuit is connected to the zero line of the input connection; furthermore, on the basis of a comparison of the second intermediate circuit voltage with the first intermediate circuit voltage, it is determined whether the supply network connection (4) has a neutral line connected to the neutral line phase (N).

Description

Technical Field

[0001] The present invention relates to a charger for operating motor vehicles, particularly a method for an on-board charger for motor vehicles, wherein the charger has a multi-phase input connector for connection to a multi-phase supply network connector for connection to a multi-phase power supply network, particularly a fixed power supply network, and has a voltage converter, wherein the voltage converter has at least one intermediate circuit with at least one intermediate circuit capacitor.

[0002] Furthermore, the present invention relates to a charger for motor vehicles, particularly configured as an on-board charger for motor vehicles, having a multi-phase input connector for connection to a multi-phase supply network connector for connection to a particularly fixed power supply network, and having a voltage converter having an intermediate circuit with at least one intermediate circuit capacitor, and having a controller.

[0003] Furthermore, the present invention relates to the energy system of a motor vehicle having the charger mentioned above, and to a motor vehicle having such an energy system. Background Technology

[0004] Power grids vary globally, distinguished by their grid voltage, frequency, and distribution system. With the increasing electrification of motor vehicles, in particular, the demand for chargers capable of connecting to different power networks to charge the energy storage devices of motor vehicles is rising. Chargers for charging the high-voltage batteries of electric vehicles can, for example, connect multiple available electrical phases to one or more phases of the power supply network connector. Such chargers typically include a voltage converter in addition to the input connector, which converts, for example, the AC voltage provided by the power supply network to a DC voltage suitable for the energy storage device. These chargers can be configured either as on-board chargers (as part of the vehicle's energy system) or as standalone chargers carried by the user and connected externally.

[0005] As is known in the prior art, a voltage sensor is assigned to each phase of the input terminal in order to determine the power grid configuration by evaluating the detected voltage. For this purpose, multiple parameters are typically evaluated for each detected voltage. These parameters are, for example, absolute voltage and effective voltage, and / or the frequency and phase of the voltage signal for the corresponding phase. The power grid configuration is then derived from a comparison of the parameters assigned to each phase.

[0006] In the case of a three-phase connection and symmetrical operation of the charger, the neutral wire connection can be omitted because the phase currents in the neutral wire are canceled out by symmetrical operation. However, the presence or absence of a neutral wire on the supply network connector side is important for the charger's regulation design. Although most on-board chargers for motor vehicles have a wired neutral wire, or neutral phase, wall-mounted boxes with a three-phase connection without a neutral wire are also provided. Summary of the Invention

[0007] The method according to the invention, possessing the features of claim 1, has the advantage of being able to detect the presence of a neutral wire in an advantageous manner using devices typically present in the charger. According to the invention, after the input connector is connected to the supply network connector, a first intermediate circuit voltage is detected using an intermediate circuit voltage sensor, preferably in time before the intermediate circuit is connected to the neutral wire of the input connector by means of a controllable fourth switching element, and preferably in time after the intermediate circuit is connected to the neutral wire of the input connector, a second intermediate circuit voltage is detected, and based on a comparison of the second intermediate circuit voltage and the first intermediate circuit voltage, it is determined whether the supply network connector has a neutral wire connected to the neutral wire. Depending on the presence or absence of a neutral wire, different charging characteristics of the intermediate circuit, or intermediate circuit capacitor, are obtained. Once the charger is connected to the supply network connector via the input connector, and before the actual charging process begins, a pre-charging of the intermediate circuit is typically performed, for example, by means of a so-called pre-charging resistor. Based on this pre-charging, there is a reliable indication as to whether the neutral wire is connected. Therefore, it is possible to identify, in a simple way and manner, whether the connected supply network connector has a neutral wire connected to the neutral wire. Preferably, the method includes the step of controlling the charger based on the identification of the connected neutral wire of the supply network connector.

[0008] Preferably, the presence of a neutral wire is inferred when the calculated second intermediate circuit voltage is higher than the calculated first intermediate circuit voltage, especially when it exceeds a predetermined limit. A higher calculated second intermediate circuit voltage is only obtained when the neutral wire is connected, thus providing a good basis for the existence of a neutral wire, especially when the voltage exceeds the limit.

[0009] According to a preferred embodiment of the invention, a neutral wire is inferred to be present when the second intermediate loop voltage corresponds to the expected voltage difference between the positive and negative peak voltages of the phase of the applied voltage at the input connector, particularly the conductor phase. After the input connector is connected to the supply network connector, the voltage applied to the conductor phase causes pre-charging of the intermediate loop, or intermediate loop capacitor. If the neutral wire is connected, the intermediate loop voltage is charged to the voltage difference (so-called peak-to-peak voltage), which is higher than the intermediate loop voltage when the neutral wire connector is disconnected or absent.

[0010] Furthermore, preferably, the first phase (i.e., the conductor phase) of the phase has a first switching element between the input connector and the voltage converter, and the second phase (also a conductor phase) of the phase has a third switching element between the input connector and the voltage converter. Pre-charge resistors are connected in parallel to the first and third switching elements, respectively. The first and third switching elements are operated to: disconnect the corresponding phase from the voltage converter in a static state, preferably maintaining the connection via the pre-charge resistor; and connect at least one of the first and second phases to the voltage converter in a charging state, preferably across the pre-charge resistor. Preferably, the charging state means that the energy storage device connected to the charger is preferably charged with a charging current. In the static state, which also exists before the input connector is connected to the supply network connector, the disconnected first and third switching elements prevent direct connection between the voltage converter and the corresponding conductor phase. However, the pre-charge resistor allows a defined current flow that results in charging of the intermediate loop. The first or second phase is connected to the voltage converter by manipulating or closing the first and / or third switching element only when charging is in operation or the charging state is activated, thereby bypassing the corresponding pre-charge resistor and thus bypassing the current flow limit.

[0011] Preferably, the third phase (preferably also a conductor phase) of the phase has a second switching element between the input terminal and the voltage converter. This second switching element is operable to connect the third phase of the voltage converter to the first phase in a static state and to connect the third phase of the voltage converter to the third phase of the input terminal in a charging state. Therefore, in a static state, the same voltage as applied to the first phase is applied to the third phase of the voltage converter, wherein the third switching element is connected to the first phase between the first switching element and the voltage converter, such that in a static state, whenever the first switching element is disconnected, the voltage of the first phase, or pre-charging current, is applied to the third phase.

[0012] Furthermore, it is preferably configured that after the input connector is connected to the supply network connector, at least one first voltage applied to the first phase and one second voltage applied to the second phase are monitored or determined, wherein the expected voltage difference is determined based on the first and second voltages. The connection between the input connector and the supply network connector is preferably identified by the presence of a pre-charging current or a voltage appearing in one phase while the charger is stationary. Because the intermediate circuit is charged by the pre-charging current, an intermediate circuit voltage is generated. The peak-to-peak voltage, or the expected voltage difference, is determined based on the voltages detected in the first and second phases.

[0013] Particularly preferably, the expected voltage difference is obtained from the phase-to-phase correlation of the first and second voltages. When the neutral wire connection is connected, the so-called phase-to-phase voltage is applied to the intermediate circuit, such that the phase-to-phase voltage and the voltage difference derived from it allow for a reliable conclusion regarding the existence of the neutral wire connection.

[0014] The outstanding feature of the charger according to the invention, having the features of claim 8, is that the charger is specifically configured to implement the method according to the invention when used in accordance with the prescribed usage. This results in the advantages already mentioned above.

[0015] The outstanding feature of the energy system according to the invention, having the features of claim 9, is the charger according to the invention. This provides the advantages already mentioned above.

[0016] The distinguishing feature of the motor vehicle according to the invention, having the features of claim 10, is the energy system according to the invention. This results in the advantages already mentioned above. Attached Figure Description

[0017] The invention will now be explained in more detail with reference to the accompanying drawings.

[0018] Figure 1 A simplified diagram illustrates an advantageous charger for motor vehicles. Figure 2 A flowchart illustrating an advantageous method for operating the charger is shown, and Figure 3 A diagram is shown to further explain this advantageous method. Detailed Implementation

[0019] Figure 1A simplified diagram shows an advantageous charger 1 for an energy system 2 of a motor vehicle (not shown in more detail here). The charger 1 has an input connector 3 on the input side, configured to connect to a supply network connector 4 of a fixed power supply network. For this purpose, the input connector 3 and the supply network connector 4 are configured as plug-in connectors for establishing a plug-in connection. The input connector 3 has connectors L1, L2, L3, a neutral connector N, and a protective conductor connector PE. Connectors L1, L2, and L3 represent the connectors of the conductor phases of the charger 1, which are connected to a voltage converter 5 of the charger 1. The voltage converter 5 is configured to provide a DC voltage according to the connected power supply network or supply network connector 4, preferably at an intermediate connector 6. Preferably, the voltage converter 5 is designed as a power factor correction stage or a power-factor-correction stage. Preferably, the intermediate connector 6 includes a positive intermediate connector and a negative intermediate connector. A series circuit of a first intermediate circuit capacitor 14 and a second intermediate circuit capacitor 15 is preferably connected between the positive intermediate connector and the negative intermediate connector. A DC-DC voltage converter (not shown) is preferably connected to the intermediate connector 6. The DC voltage applied to the DC-DC voltage converter at the intermediate connector 6 on the input side is preferably converted into a charging voltage for charging an energy storage device (preferably a battery, traction battery, or high-voltage battery) that can be connected to the output side of the DC-DC voltage converter. Thus, by means of this charging voltage, the energy storage device of the motor vehicle connected to the charger 1 on the output side can be charged. For this purpose, the voltage converter 5 preferably has three half-bridges 7, 8, and 9, each half-bridge having two semiconductor switches 7H, 7L, 8H, 8L, and 9H, 9L connected in series, one of which is configured as a high-side switch (H) and the other as a low-side switch (L). Preferably, the half-bridges 7, 8, and 9 and the intermediate connector 6 are connected in parallel to ground, wherein each half-bridge 7, 8, and 9 has an intermediate tap between the corresponding semiconductor switches 7H, 7L, 8H, 8L, 9H, and 9L, and the intermediate tap is connected to one of the connectors L1, L2, or L3 by means of inductors or resistors 10, 11, and 12.

[0020] The voltage converter 5 further includes an intermediate circuit 13, which has a first intermediate circuit capacitor 14 and a second intermediate circuit capacitor 15, connected in series with each other and in parallel with the half-bridges 7, 8, and 9 to ground. Two unloaded diodes 16 and 17 are connected in parallel with the intermediate circuit capacitors 14 and 15. The unloaded diodes 16 and 17 are connected in the cutoff direction to prevent current from flowing from the high side to the low side of the voltage converter 5, wherein the center tap between the diodes 16 and 17 is connected to the neutral line N. Preferably, the voltage converter 5 is connected to the input terminal 3 on the input side and to the intermediate terminal 6 on the output side. Preferably, the intermediate terminal 6 is connected in parallel with the half-bridges 7, 8, and 9 or a series circuit consisting of the first and second intermediate circuit capacitors 14 and 15.

[0021] The charger 1 preferably further includes a first switching element S1, through which half-bridge 7 can be optionally connected to connector L1. Furthermore, the charger 1 preferably includes a second switching element S2, through which third half-bridge 9 is connected to connector L1 or the first phase of voltage converter 5 in a first switching position, and to connector L3 or the third phase of input connector 3 in a second switching position. Furthermore, the charger 1 preferably includes a third switching element S3, through which second half-bridge 8 can be optionally connected to connector L2. By means of a fourth switching element S4, the center tap between diodes 16 and 17 can be optionally connected to the center tap between first intermediate circuit capacitor 14 and second intermediate circuit capacitor 15.

[0022] Furthermore, the charger 1 preferably has voltage sensors V7, V8, and V9 respectively assigned to the corresponding half-bridges 7, 8, and 9. These voltage sensors are connected between the corresponding phase and neutral terminals N of the voltage converter 5 to detect the voltage of the corresponding terminals L1, L2, and L3 relative to the neutral terminal N. Currently, it is also preferable to additionally assign current sensors A10, A11, and A12 to the resistors or inductors 10, 11, and 12 respectively.

[0023] The charger 1 also has a controller 18, which is configured to operate the semiconductor switches of the voltage converter 5 and monitor the values ​​detected by the voltage sensors V7-V9 and / or the current sensors A10-A12.

[0024] The controller 18 is specifically configured to implement the methods described below. Figure 2 A flowchart is shown as an example to illustrate this advantageous method. The method preferably begins in step S_1 as the charger 1 starts operating, when the input connector 3 is connected to the supply network connector 4.

[0025] Furthermore, a pre-charging resistor S1R or S3R is connected in parallel to the first switching element S1 and the third switching element S3, respectively. A fourth voltage sensor V13 is connected in parallel to the intermediate circuit 13. This fourth voltage sensor measures or monitors the voltage at the intermediate circuit 13, or the voltage drop at the series circuit of the first and second intermediate circuit capacitors (14, 15), or the intermediate circuit voltage.

[0026] In the stationary state of charger 1, i.e., before input connector 3 is connected to supply network connector 4, it is preferable to operate the first to third switching elements S1, S2, and S3, which interrupt the respective assigned phases L1, L2, and L3, or in the case of switching element S2, connect phase L3 to phase L1. If a voltage is applied at one of the conducting phases L1 and / or L2, the connection between input connector 3 and supply network connector 4 at time t0 is caused by the current flow through the at least one corresponding pre-charging resistor S1R, S3R, and at least one intermediate circuit capacitor of intermediate circuit capacitors 14, 15 is charged, which can be detected by the fourth voltage sensor V13. Preferably, current sensors A11 and A12 also detect the current flow. Thus, controller 18 recognizes that input connector 3 has been connected to supply network connector 4, or that at least one of the phases is providing voltage. If the connection is detected at time t0, the method is initiated in step S_1. Here, when the fourth switching element S4 is in Figure 1 When the circuit shown is disconnected, the intermediate circuit 13 is charged.

[0027] After a predetermined time, or when the detected voltage of the intermediate circuit no longer changes significantly or changes further, in step S_2, at time point t1, the fourth switch S4 is operated to connect the intermediate circuit 13 or the intermediate tap between the first and second intermediate circuit capacitors 14 and 15 to the neutral line N. The intermediate circuit 13 is also passively precharged, i.e., only via pre-charge resistors S1R and S3R. However, after closing the fourth switch S4, the voltage detected by the fourth voltage sensor V13 varies depending on whether a neutral line of the power supply network is connected at the neutral phase N.

[0028] Figure 3 A simplified diagram is shown here, illustrating the voltage signal detected by the fourth voltage sensor V13. The voltage signal is plotted with respect to time t, including the start of the method at time t0 and the time t1 at which the fourth switching element S4 is closed. The intermediate loop 13 is pre-charged to the amplitude of the interphase voltage uACL12(t), which is composed of the voltages uACL1(t) and uACL2(t) of conductor phases L1 and L2.

[0029] However, if the neutral wire is connected to this phase, the intermediate circuit 13 is charged to a so-called peak-to-peak AC voltage, that is, charged to the voltage difference between the positive peak voltage and the negative peak voltage of the phase (or interphase voltage) of the voltage applied to the input terminal. Thus, different voltage levels are generated after closing the fourth switching element S4. If the neutral wire is not connected, the voltage in the intermediate circuit at time t1 changes little or only slightly compared to the previous time period. However, if the neutral wire connection is present, the voltage level rises to the voltage difference (as in...). Figure 3 (As shown by the envelope curve), this creates a voltage difference between the time period before and after closing the fourth switching element S4. If the controller 18 identifies this voltage level switch or difference, it infers the presence of a neutral wire in the power supply network. If no corresponding voltage difference is identified, it is ruled out that the power supply network does not have a corresponding neutral wire.

[0030] Preferably, in step S_3, the voltage detected in the intermediate loop 13 from time point t1 is compared with the expected voltage difference (i.e., the expected peak-to-peak voltage of the phase-to-phase associated input voltage uACL12(t)). If the voltage level after closing the switching element S4 corresponds to the expected voltage difference, it is inferred that there is a neutral connection in the power supply network. If the voltage level does not correspond to the expected voltage difference, it is inferred that there is no neutral connection in the power supply network.

[0031] Accordingly, in step S_4, it is determined whether the power supply network has a neutral wire or not, and preferably the power grid configuration of the power supply network, or the power supply network connector 4, is determined accordingly, and / or the optimal charging process is initiated by the charger 1. Therefore, the charger 1 is controlled based on the identification of the neutral wire connected to the power supply network connector 4.

Claims

1. A method for operating a charger (1) for a motor vehicle, particularly an on-board charger for a motor vehicle, wherein, The charger (1) has a multiphase input connector (3) for connection to a multiphase supply network connector (4) of a particularly fixed power supply network, and a voltage converter (5), wherein the voltage converter (5) has at least one intermediate circuit (13) with at least one first intermediate circuit capacitor and a second intermediate circuit capacitor (14, 15), characterized in that, after the input connector (3) is connected to the supply network connector (4), the first intermediate circuit voltage of the intermediate circuit (13) is detected by means of a fourth voltage sensor (V13) of the intermediate circuit (13) before the intermediate circuit (13) is connected to the neutral phase (N) of the input connector (3) by means of a controllable fourth switching element (S4), and the second intermediate circuit voltage of the intermediate circuit (13) is detected after the intermediate circuit is connected to the neutral phase of the input connector; and, based on the comparison between the second intermediate circuit voltage and the first intermediate circuit voltage, it is determined whether the supply network connector (4) has a neutral wire connected to the neutral phase (N).

2. The method according to claim 1, characterized in that, When the voltage of the second intermediate circuit is higher than that of the first intermediate circuit, especially higher than a predetermined limit, it is inferred that the zero line exists.

3. The method according to claim 1, characterized in that, The presence of the neutral line is inferred when the second intermediate circuit voltage corresponds to the expected voltage difference between the positive and negative peak voltages of the phase of the applied voltage at the input terminal.

4. The method according to any one of the preceding claims, characterized in that, The first phase (L1) of the phase has a first switching element (S1) between the input connector (3) and the voltage converter (5), and the second phase (L2) of the phase has a third switching element (S3) between the input connector (3) and the voltage converter (5). Pre-charge resistors (S1R, S3R) are connected in parallel with respect to the first switching element (S1) and the third switching element (S3), respectively. The first switching element and the third switching element (S1, S3) are manipulated to disconnect the corresponding phase (L1, L2) from the voltage converter (5) in a static state and to connect at least one of the first phase and the second phase (L1, L2) to the voltage converter (5) in a charging state.

5. The method according to claim 4, characterized in that, The third phase (L3) of the phase has a second switching element (S2) between the input connector (3) and the voltage converter (5). The second switching element is operated to connect the voltage converter (5) to the first phase (L1) in the static state and to connect the voltage converter (5) to the third phase (L3) in the charging state.

6. The method according to claim 5, characterized in that, After the input connector (3) is connected to the supply network connector (4), at least one first voltage of the first phase (L1) and at least one second voltage of the second phase (L2) are monitored, wherein the expected voltage difference is obtained based on the first voltage and the second voltage.

7. The method according to claim 6, characterized in that, The expected voltage difference is obtained from the phase correlation between the first voltage and the second voltage.

8. A charger (1) for motor vehicles, particularly an on-board charger for motor vehicles, having a multi-phase input connector (3) for connection to a multi-phase supply network connector (4) for connection to a multi-phase power supply network, particularly a fixed power supply network, and having a voltage converter (5), wherein, The voltage converter (5) has at least one intermediate circuit (13) with at least one first intermediate circuit capacitor and a second intermediate circuit capacitor (14, 15), characterized in that it has a controller (18) specifically configured to implement the method according to any one of claims 1 to 7 when used in accordance with the prescribed use.

9. An energy system (2) for a motor vehicle, having at least one electrical energy storage device, characterized in that, The energy storage device is equipped with a charger (1) according to claim 8.

10. A motor vehicle having the energy system (2) according to claim 9.

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