Vehicle-side alternating-current producer with individual fault-current-monitored mains voltage output points and central fault-current-dependent switch-off

Abstract

A vehicle alternating current producer is equipped with an alternating current source (PFC / DCDC), a switching unit (SW) downstream of the alternating current source (PFC / DCDC), a plurality of output points (S1 – S3) and a distributor (V). The switching unit (SW) is connected to the output point (S1 – S3) via the distributor (V). A fault current measurement device (M1 - M3) is provided in each case between the distributor (V) and the output points (S1 – S3). The fault current measurement devices (M1 - M3) are connected for signal transmission to the switching unit (SW). The switching unit (SW) is configured to disconnect the alternating current source (PFC / DCDC) from the distributor (V) when one or more of the fault current measurement devices (M1 - M3) detects a fault current value which is above a predefined threshold value. The invention also relates to a related method.

Description

[0001] Vehicle-mounted alternator with individually fault current monitored

[0002] Mains voltage supply points and central residual current-dependent shutdown

[0003] Description

[0004] Vehicles generally have electrical energy storage devices that are either used directly to generate traction power or to supply the vehicle's electrical components (starter, control units, safety devices, entertainment components, etc.). It is known to use this electrical energy storage device, be it a high-voltage accumulator or a 12 V battery, to generate a standard mains alternating voltage, with a converter generating an alternating voltage with a standardized frequency and voltage from the direct voltage of the energy storage device. Since the level of the mains voltage, for example 110 V or 230 V, is fundamentally dangerous depending on the region, particularly when used in potentially damp outdoor areas as is typical in the vehicle context, one task is to provide reliable and simple protection against excessive touch voltage in the event of faulty insulation.

[0005] This object is achieved by the subject matter of claims 1 and 10. Further properties, features, embodiments, areas of application and advantages emerge from the description and the figure.

[0006] It is proposed that, where there are multiple supply points, each one be individually equipped with a residual current sensor. However, instead of installing a circuit breaker at the same location as the residual current sensor, as is usual, a central switching unit be provided which, upon detection of a residual current at a supply point, centrally interrupts the voltage supply to the supply points. This means that only one sensor is required for each supply point, and only one switching unit is required for all supply points. This makes it possible to detect individual residual currents which would not be detectable with central detection, for example due to mutual compensation. This means that each supply point is individually monitored for residual currents, while the safety mechanism, namely the switching unit, only needs to be provided centrally once.

[0007] Several output points of a vehicle are thus connected to a distributor, whereby the distributor is connected to an AC power source via a switching unit. A fault current sensor is provided at each output point or between each output point and the distributor. If a fault current occurs (which is above a threshold value), the voltage can be disconnected centrally by the switching unit, preferably across all poles, in order to disconnect the distributor from the AC power source. If the distributor is disconnected from the AC power source, then the output points are also necessarily disconnected from the AC power source, since the output points are connected downstream of the distributor (seen from the AC power source).

[0008] The residual current sensors are connected to the switching unit for signal transmission. The switching unit is designed to disconnect when at least one of the residual current sensors transmits a residual current that exceeds a threshold value. This allows the residual currents at the respective output points to be considered individually, preventing the individual residual currents from overlapping and (partially) compensating or canceling each other out, which would impair detection.

[0009] A vehicle alternator can therefore be designed with an alternating current source, a distributor, and a switching unit between the alternating current source and the distributor. This creates a common power path that divides at the distributor into several individual power paths, with the individual power paths leading to individual output points. A residual current measuring device monitors each individual power path. The residual current measuring devices are connected to the switching unit in such a way that the switching unit disconnects the common power path if one or more of the residual current measuring devices detect a residual current value that exceeds a predetermined threshold. If this condition is met, the alternator is preferably also designed to deactivate the alternating current source, in particular before it is disconnected by the switching unit.

[0010] A corresponding method provides for a common power path between an AC power source and a distributor in a vehicle electrical system to be disconnected (preferably by a switching unit between the source and the distributor) if at least one of several individual power paths leading from the distributor has a fault current above a predetermined threshold. The vehicle can be a battery-powered electric vehicle ("BEV"), a hybrid vehicle ("HEV"), or an internal combustion engine-powered vehicle. A DC voltage source for supplying the AC power source can be provided by the traction battery (if present) or by the starter battery (12 V, 48 V).

[0011] A vehicle alternator comprising an alternating current source, a switching unit, and a distributor is described. The switching unit is provided between the alternating current source and the distributor and is configured to disconnect the connection between the alternating current source and the distributor. Alternatively or in combination therewith, a direct voltage connection is connected to a direct current side of the alternating current source via a switching unit. The alternating current source is, in particular, a converter configured to convert a direct voltage on a direct voltage side of the alternating current source into an alternating voltage (on an alternating voltage side of the alternating current source). Such an alternating current source is also referred to as an inverter. The alternating current source is, in particular, an alternating current source configured to output a single-phase alternating voltage.The inverter is configured to output an alternating voltage with a frequency and amplitude corresponding to an alternating voltage of a standardized alternating voltage supply network. The frequency can be, for example, 50 or 60 Hz. The effective alternating voltage can be, for example, 100 V, 110 V, or 120 V, or even 220 V, 230 V, or 240 V. The alternating voltage is preferably a sinusoidal voltage. The alternating voltage side of the alternating current source can have a phase potential and a neutral conductor potential, with the alternating voltage being provided between these terminals. The alternating current source is, in particular, an alternating current source configured to output a single-phase alternating voltage.

[0012] The switching unit is preferably an electromechanical switch unit. The switching unit can have a relay. The switching unit can be designed as an electromechanical switch in the sense of a relay, or can be designed as an electronic fuse or a pyroelectric fuse. The switching unit is preferably all-pole, i.e. it has two power paths that can each be (simultaneously) disconnected. In particular, the switching unit is provided to disconnect both a phase potential and a neutral conductor potential, which is provided by the alternating current source, from the distributor. The distributor is thus connected to the alternating current source via the switching unit, wherein a neutral conductor potential of the distributor is connected to a neutral conductor potential of the alternating current source, and a phase potential of the distributor is connected to a phase potential of the alternating current source.The connection is made via the switching unit, which can separate both potentials.

[0013] The alternator also has several outlets. These can themselves be designed as sockets according to a standard for the design of sockets in a power grid. The outlets are preferably provided as contact points, in particular plug-in connections, to which sockets (standardized according to a power grid standard) can be connected, for example via respective cables. The connections (corresponding to the individual power paths) between the outlets and the distributor are preferably free of switches that are actuated depending on a detected fault current. Instead, the switching unit serves for fault-current-dependent disconnection.

[0014] A residual current measuring device is provided between the distributor and the supply points. A residual current measuring device is provided between each supply point and the distributor. This means that the residual current measuring devices measure the residual currents to the respective potentials of the supply points and, due to the connection, also to the relevant lines between the supply points and the distributor, as well as to the conductors and consumers connected to the supply points. The specific arrangement of the measuring devices is of secondary importance; rather, the measuring devices are designed to measure residual currents of the potentials delivered from the distributor to the supply points.

[0015] A fault current is the difference between the currents of the two conductors (supply and return conductors) that emanate from the distributor (towards the delivery points). The fault current provides information about whether the entire current transmitted by the supply conductor is also returned (transmitted) by the return conductor, or whether insulation problems result in an additional current in addition to the current through the return conductor. Such an additional current would, for example, lead to a ground or earth potential in the event of insulation faults, although it cannot be ruled out that this fault current flows through a user. Therefore, if a fault current above a threshold value is detected, the switching unit is triggered to disconnect in order to prevent the voltage from being delivered to the delivery points (i.e. to all delivery points connected to the distributor). The fault current measuring devices are controlling or signal-transmitting orlogically connected or linked to the switching unit. The switching unit is logically subordinate to the measuring devices, which means that certain events detected by the measuring devices lead to a change of state in the switching unit. This applies in particular to at least one fault current that lies above a threshold value, which results in the switching unit being controlled to open via additional logic or directly. The switching unit is designed to disconnect the AC power source from the distributor (and / or to disconnect the AC power source from a DC voltage supply) if one or more of the fault current measuring devices detect a fault current that lies above a predetermined threshold value. In this case, the switching unit can be designed to open depending on the signals emitted by the measuring devices.The logic for detecting whether one or more detected fault currents are above a threshold value can be provided within the switching unit, can be provided within a calculation or logic unit located between the measuring devices and the switching unit, or can be assigned to a higher-level control unit.

[0016] This logic is preferably implemented in a logic unit. The logic unit is provided in particular in the switching unit. The logic unit can also be connected upstream of the switching unit. The switching unit can also be referred to as a breaker or isolating unit. The switching unit is designed to interrupt a power flow, in particular with a (switching) current of at least 10 A, 50 A or 100 A. The logic unit is designed to compare the fault current emitted by the residual current measuring devices with a threshold value. Alternatively, the logic unit can be designed to determine whether one of the residual current measuring devices detects a fault current that lies above a threshold value.It can be provided that the residual current measuring devices either emit a signal that represents the detected fault current, for example, numerically, or that the residual current measuring devices emit a signal that indicates whether the detected fault current exceeds a threshold value. In the latter case, the assessment of whether the detected fault current exceeds a threshold value is carried out by the residual current measuring device (or a measuring device logic associated with a respective measuring device). Comparators can be provided that compare the detected fault current with the respective threshold value.These comparisons can be implemented in the switching unit, in particular in a logic unit within the switching unit, can be provided in a logic unit that is connected upstream of the switching unit (with the measuring devices being connected to this unit), or can be provided in the measuring devices or in a respective measuring device logic that is assigned to an individual measuring device (or is provided between this and the switching unit). The evaluation of whether the measuring devices detect one or more fault current values ​​that lie above a predetermined threshold can thus be implemented decentrally in the measuring devices or centrally in the switching unit in a consolidating logic.

[0017] The switching unit opens (or the overall power flow is interrupted) if at least one of the detected fault currents exceeds a threshold. Thus, an OR connection exists between the detected fault currents, with the result of the OR connection determining the switching state of the switching unit. The OR connection exists specifically between the comparison results of the fault currents and the threshold. The comparison results are binary and indicate whether the threshold has been exceeded or not.

[0018] The alternator can be configured not only to open the switching unit if at least one of the fault currents exceeds a threshold value, but also to deactivate the alternating current source if this condition is met. In particular, the logic unit can be configured to transfer the alternating current source to an inactive state (or to provide this state) if one or more of the fault current measuring devices detect a fault current that exceeds the threshold value. The alternating current source is designed, in particular, as a clocked converter (inverter). The alternator can be configured to suppress the consideration of the converter if at least one of the fault currents exceeds the threshold value. For this purpose, the logic unit, the switching unit, or the measuring devices can be connected to the alternating current source or an associated controller in a controlling manner.

[0019] Preferably, the alternator is configured to first place the AC power source in an inactive state and then open the switching unit if at least one of the detected fault currents exceeds the threshold value. This opens the switching unit in the de-energized state, resulting in less wear. A controller may be provided that first places the AC power source in an inactive state and then opens the switches, with the controller additionally only opening the switching unit after a minimum period of time has elapsed since the AC power source has been set to the inactive state.

[0020] The output points are preferably single-phase. The output points can comprise a contact for a phase potential and a contact for a neutral conductor potential. The output points are in particular free of protective conductor contacts or have an unconnected protective conductor contact (if permitted). The output points can be designed as a connection element for a (two-wire) cable leading to a socket. This socket is designed in particular according to a standard for sockets of a supply network, for example according to the NEMA 1-15 standard (complementary to plug type A) or CEE 7 / 16, CEE 7 / 17, CEE 7 / 7, in particular according to a two-pole household socket according to the respective supply network standard in Japan or the USA. Sockets that do not have an earthing contact or have an unearthed earthing contact are described as two-pole.

[0021] The switching unit is preferably designed for all-pole isolation. In an electromechanical design, an electromagnetic factor acts on two separate contacts, with one of the contacts being assigned, for example, to a phase potential and the other to a neutral conductor potential. Alternatively, the two contacts can be assigned to two different phase potentials. All-pole isolation refers (exclusively) to lines that carry current in a fault-free, active operating state, i.e., that carry load current.

[0022] The residual current measuring devices each preferably comprise a differential current sensor. A (soft magnetic) magnetic material can be provided which surrounds both conductors (neutral conductor / phase conductor or first phase conductor / second phase conductor). The magnetic material encloses a hollow space through which the conductors extend. A sensor winding surrounds the magnetic material, but not the conductors, in order to record the overall magnetization resulting from the two conductors. The sensor winding on the one hand and the conductors on the other hand form the primary and secondary sides of a transformer. If the currents through the two conductors are identical but with different signs, there is no signal for the sensor winding because the magnetic fields of the two conductors cancel each other out. If the two currents are not identical, i.e. if a residual current orDifferential current, then a signal is generated for the sensor winding that corresponds to the difference in the magnetic fields and thus the difference in the currents. Since the alternator uses alternating current, the sensor winding detects an alternating field that represents the differential current or its time derivative. Alternatively, the currents through the two conductors can also be detected using shunts or two magnetic sensors, each assigned to one of the conductors. The difference is then determined by calculating the difference between the two signals emitted by the two shunts / magnetic sensors.

[0023] The residual current measuring devices can each have communication means to output the measured current or differential current value as a signal. In the simplest case, the communication means are simple conductors and corresponding taps, but can also include signal amplifiers, analog-to-digital converters, and / or communication devices configured according to a data transmission standard (Ethernet protocol, CAN, generally wired or wireless transmission protocols, which are particularly designed for packet- or circuit-switched transmission).

[0024] The alternating current source can be provided within a bidirectional charging device. The alternating current source can be designed to be bidirectional, in particular for a charging mode in which power is transferred from the alternating current side of the alternating current source to the direct current side of the alternating current source (rectification), and for a discharging mode in which power is transferred from the direct current side to the alternating current side (conversion). Such a charging device can comprise a direct current connection, for example for a rechargeable battery, and an alternating current connection. Such charging devices are then configured in the discharging mode to transfer power from the direct current connection and convert it into an alternating voltage, for example to operate external loads, as provided for by the procedure described here, or to transfer power from the direct current connection to an alternating current supply network.Alternatively, the AC power source is a dedicated converter whose DC side is connected to a DC terminal (e.g., for a storage battery) to power an external load. External loads are loads that are not necessarily part of the vehicle and are designed to operate with AC voltage according to an AC power grid standard. A dedicated converter is a converter that is not within the power flow of a charging station. The DC side of the AC power source can be connected to a traction battery or a high-voltage on-board network section of the vehicle, or can also be connected to a 48 V or 12 V battery of the vehicle. The vehicle alternator, and thus also the AC power source, are preferably provided within a vehicle and are, in particular, permanently installed there.The AC power source is provided in particular as a bidirectional AC charging device (for charging with alternating current), wherein this charging device has a DC voltage side that is connected or connectable to a high-voltage battery of the vehicle's electrical system. The AC voltage side of the alternator or AC power source is connected to the switching unit, in particular directly, preferably without a converter and / or via a fuse.

[0025] Figure 1 serves to explain the mode of operation of embodiments of the alternator described here.

[0026] Figure 1 shows a vehicle F in which an on-board charging device (OBC) is provided. In the example shown, a power factor correction filter (reference symbol PFC) and a connected DC-DC converter (reference symbol DCDC) together serve as an AC voltage source (reference symbol PFC / DCDC). The AC voltage source PFC / DCDC is powered by a battery B, which is connected to a DC voltage side of the AC voltage source. The battery B (or a corresponding battery connection) is connected to the power factor correction filter PFC via the DC-DC converter. The AC voltage side of the power factor correction filter PFC corresponds to the AC voltage side of the AC voltage source PFC / DCDC.

[0027] The PFC / DCDC alternating voltage source is connected to a distributor V via the switching unit SW. Several connection points S1 to S3 are individually connected to the distributor V. Each of the connection points S1 to S3 is connected to the distributor V via its own measuring device M1-3. The distributor V thus forms a common node to which the connection points S1 to S3 are connected. The measuring devices M1 - M3 are individually provided so that residual current detection can take place for each connection point (or for the respective potentials). The measuring devices M1 to M3 are residual current measuring devices. These are designed to detect the respective current difference between a forward and a return conductor via which the distributor V is connected to the several connection points S1 to S3.

[0028] In the example shown, external loads L1 to L3 are connected to connection points S1 to S3 so that loads L1 to L3 can receive power from connection points S1 to S3. This is schematically represented by the arrows between connection points S1 - S3 and loads L1 - L3. The respective power flow originates from distributor V and leads via measuring devices M1 to the connection points. This is also represented by the arrows between distributor V and connection points S1 to S3. Connection points S1 - S3 are in particular sockets into which loads L1 - L3 are plugged, or are connecting elements that are connected via cables to sockets into which loads L1 to L3 are plugged. Loads L1 to L3 are external to the vehicle's electrical system, this is represented by the reference symbol EXT. Loads L1 to L3 can be plugged into connection points S1 to S3 as external loads.The electrical connection is shown schematically, so that the representation of the loads L1 to L3 outside the rectangle that characterises the vehicle F merely indicates that the loads L1 to L3 are provided outside the vehicle's electrical system and are only connected to it, whereby it is irrelevant whether the load is physically arranged inside the vehicle F or outside the vehicle F.

[0029] In the variant shown, the switching unit SW comprises a logic unit L. The measurement results are transmitted to this logic unit, whereby the measurement results originate from the measuring devices M and M1 to M3. The arrows emanating from M1 - M3 thus represent the logical connection between the measuring devices M1 to M3 and the logic unit L. As an alternative to the variant shown, the logic unit L can also be located outside the switching unit SW, for example at location X. In this case, the logic unit controls the switching unit SW.

[0030] The logic unit is connected to the (two-pole) switch of the switching unit SW. The switching unit is thus designed to interrupt the power flow from the alternating current source to the distributor V. This results in a common isolating device in the form of the switch SW for all three power branches shown. If only one of the measuring devices M1 to M3 transmits a detected fault current to the logic unit L that is greater than a specified threshold, the switch in the switching unit opens. This interrupts the power flow to all connection points. The threshold specifies a limit above which a dangerous touch current can exist. The threshold can be specified by a safety standard. If the loads L1 and L2 have insulation faults that lead to fault currents that can compensate for each other, only the compensated fault current can be detected at the distributor V.Faults can thus remain undetected or be mistakenly neglected. For this reason, individual power paths are provided upstream of the distribution board V, each of which is monitored for fault currents using a measuring device M1 to M3. This allows the fault currents to be monitored individually.

[0031] The illustrated vehicle electrical system of the vehicle F can be operated in such a way that a common power path G, which extends (at least) between the alternating current source PFC / DCDC and the distributor V, is disconnected if at least one of several individual power paths E1, E2, E3 leading from the distributor V has a fault current above a predetermined threshold value. The fault current is determined in particular by the measuring devices M1 - M3. The individual power paths E1 - E3 lead at least from the distributor to the output points S1 - S3 and in particular continue to the loads L1 - L3 that are connected to the vehicle via the output points S1 - S3. The disconnection is preferably carried out by the switching unit SM.The vehicle alternator is configured to implement the method (and includes, in particular, the PFC / DCDC source, the distribution board, and the devices M1–M3 for detecting fault currents within the individual power paths). For individual power path E1, it is shown that this can extend from the distribution board to the relevant load L1. This is intended to demonstrate that the fault current detection concerns the connection outgoing from the distribution board V (toward the supply point), as well as the lines and components connected to it.

Claims

Patent claims 1. Vehicle alternator with an alternating current source (PFC / DCDC), a switching unit (SW) connected downstream of the alternating current source (PFC / DCDC), a plurality of output points (S1 - S3) and a distributor (V) via which the switching unit (SW) is connected to the output points (S1 - S3), wherein a residual current measuring device (M1- M3) is provided between the distributor (V) and the output points (S1 - S3), wherein the residual current measuring devices (M1- M3) are connected to the switching unit (SW) in a signal-transmitting manner and the switching unit (SW) is designed to disconnect the alternating current source (PFC / DCDC) from the distributor (V) if one or more of the residual current measuring devices (M1- M3) detect a residual current value which lies above a predetermined threshold value.

2. Vehicle alternator according to claim 1, further comprising a logic unit (L) provided within the switching unit (SW) or connected upstream thereof (X), the logic unit (L) being arranged to compare the fault current value output by the fault current measuring devices (M1-M3) with a threshold value.

3. Vehicle alternator according to claim 2, wherein the logic unit (L) is arranged to provide the alternating current source (PFC / DCDC) in an inactive state when one or more of the fault current measuring devices (M1-M3) detect a fault current value which is above a predetermined threshold value.

4. Vehicle alternator according to one of the preceding claims, wherein the output points are single-phase.

5. Vehicle alternator according to one of the preceding claims, wherein the switching unit is designed for all-pole separation.

6. Vehicle alternator according to one of the preceding claims, wherein the fault current measuring devices (M1 - M3) each comprise a differential current sensor.

7. Vehicle alternator according to one of the preceding claims, wherein the alternating current source (PFC / DCDC) is a bidirectional, vehicle-mounted charging device which, in a discharge mode, is configured to convert a DC voltage on a DC voltage side of the AC power source into an AC voltage on an AC voltage side of the AC power source, or which is designed as a dedicated converter.

8. Vehicle high-voltage electrical system with a vehicle alternator according to one of the preceding claims, wherein the alternating current source (PFC / DCDC) is a bidirectional alternating current charging device which has a direct voltage side which is connected to a high-voltage accumulator of the vehicle electrical system and which has an alternating voltage side which is connected to the switching unit.

9. Method for operating a vehicle electrical system, wherein a common power path (G) between an alternating current source (PFC / DCDC) and a distributor (V) is separated if at least one of several individual power paths (E1, E2, E3) leading from the distributor (V) has a fault current above a predetermined threshold value.

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