Vehicle-side alternator with separate fault current monitoring mains voltage output point and central fault current-dependent disconnection function

Abstract

A vehicle AC generator is equipped with an AC source (PFC / DCDC), a switching unit (SW) downstream of the AC source (PFC / DCDC), a plurality of output points (S1-S3), and a distributor (V). The switching unit (SW) is connected to the output points (S1-S3) via the distributor (V). A residual current measuring device (M1-M3) is provided between the distributor (V) and each of the output points (S1-S3). The residual current measuring devices (M1-M3) are connected to the switching unit (SW) in a signal transmission manner. The switching unit (SW) is arranged to isolate the AC source (PFC / DCDC) from the distributor (V) when one or more of the residual current measuring devices (M1-M3) detects a residual current value above a specified threshold. A related method is also described.

Description

[0001] Vehicles usually have electrical energy storage devices which are used to directly generate traction power or to supply electrical components of the vehicle (starter motor, control units, safety devices, entertainment components, etc.). It is known to use such electrical energy storage devices, whether high-voltage batteries or 12 V batteries, to generate an AC voltage which is compatible with the electrical grid, wherein a converter generates an AC voltage having a standardized frequency and a standardized AC voltage from the DC voltage of the electrical energy storage device. Since the level of the grid voltage, for example 110 V or 230 V, depending on the region, is inherently dangerous, in particular when used in outdoor areas which can be wet (which is common in vehicle applications), it is an object to provide protection against excessively high touch voltages in a safe and simple manner in the event of an insulation fault.

[0002] This object is achieved by the subject matter of claims 1 and 10. Further properties, features, embodiments, fields of application and advantages become apparent from the description and the drawings.

[0003] It is proposed to provide a residual current sensor individually for each of a plurality of output points, but not to arrange a breaker at the location of the residual current sensor as is usually done, but to provide a central switching unit which centrally interrupts the voltage output at the output points when a residual current is detected at the output points. The result is that for each output point only one sensor is required, wherein all output points only require one switching unit. This makes it possible to identify individual residual currents which cannot be detected due to, for example, mutually compensating currents in the case of a central detection. Thus, each individual output point is subject to individual monitoring for residual currents, whereas the safety mechanism, i.e. the switching unit, only needs to be centrally provided once.

[0004] Thus, a plurality of output points of a vehicle are connected to a common power distributor, wherein the power distributor is connected to an AC source via a switching unit. A residual current sensor can be provided at each output point or between each output point and the power distributor. If a residual current (above a threshold value) occurs, the voltage (preferably all poles) can be centrally isolated by the switching unit in order to thus disconnect the power distributor from the AC source. If the power distributor is isolated from the AC source, the output points are also necessarily isolated from the AC source, since the output points are downstream of the power distributor (from the AC source).

[0005] The residual current sensors are connected to the switching unit in a signal transmission manner. It is provided that the switching unit performs an interruption when at least one of the residual current sensors transmits a residual current above a threshold value. Thus, the residual currents at the respective output points are considered individually, so that individual residual currents cannot overlap and (partially) compensate or cancel each other out, resulting in a compromised detectability.

[0006] Thus, a vehicle AC generator can be designed with an AC source, a power distributor, and a switching unit between the AC source and the power distributor. This forms a common power path which is divided at the power distributor into a plurality of separate power paths, wherein these separate power paths lead to separate output points. Residual current measuring devices monitor each of the separate power paths. The residual current measuring devices are connected to the switching unit for control purposes in such a way that the switching unit interrupts the common power path when one or more of these residual current measuring devices detect a residual current value above a specified threshold. Preferably, the AC generator is arranged to also deactivate the AC source in the presence of such a condition, in particular before the switching unit interrupts.

[0007] In a vehicle on-board power supply system, a corresponding method provides that the common power path between the AC source and the power distributor is interrupted, preferably by a switching unit between the source and the power distributor, when at least one of the plurality of separate power paths leading from the power distributor has a residual current above a specified threshold.

[0008] The vehicle can be a battery electric vehicle ("BEV"), a hybrid electric vehicle ("HEV") or a vehicle driven by an internal combustion engine. The DC voltage source for supplying the DC voltage to the AC source can be provided by a traction battery, if present, or by a starter battery (12 V, 48 V).

[0009] A vehicle AC generator is described which has an AC source, a switching unit and a power distributor. The switching unit is arranged between the AC source and the power distributor and is arranged to interrupt the connection between the AC source and the power distributor. Alternatively or in conjunction therewith, a DC voltage connection is connected to the DC side of the AC source via the switching unit. The AC source is in particular a converter which is arranged to convert a DC voltage of the DC voltage side of the AC source into an AC voltage (of the AC voltage side of the AC source). Such an AC source is also referred to as an inverter. The AC source is in particular an AC source which is arranged to output a single-phase AC voltage. The inverter is arranged to output an AC voltage whose frequency and amplitude correspond to the AC voltage of a standardized AC voltage supply grid. The frequency can be for example 50 Hz or 60 Hz. The effective AC voltage can be for example 100 V, 110 V or 120 V, or 220 V or 230 V or 240 V. The AC voltage is preferably a sinusoidal voltage. The AC voltage side of the AC source can have a phase potential and a neutral conductor potential, wherein the AC voltage is provided between these connections. The AC source is in particular an AC source which is arranged to output a single-phase AC voltage.

[0010] The switching unit is preferably an electromechanical switching unit. The switching unit can have a relay. The switching unit can be designed as an electromechanical switch in the sense of a relay, but also as an electronic fuse or a high-temperature fuse. The switching unit preferably has a full-pole configuration, i.e. has two power paths, which can each (at the same time) be interrupted. In particular, the switching unit is provided for isolating both the phase potential and the neutral conductor potential provided by the AC source from the power distributor. The power distributor is thus connected to the AC source via the switching unit, wherein the neutral conductor potential of the power distributor is connected to the neutral conductor potential of the AC source and the phase potential of the power distributor is connected to the phase potential of the AC source. The connection passes through the switching unit, which can isolate both potentials.

[0011] The AC generator further has a plurality of output points. The output points can themselves be designed as sockets which comply with the standards for constructing sockets for power supply grids. Preferably, the output points are provided as contact points, in particular plug connections, to which sockets (standardized in accordance with the standards of the power supply grid) can be connected, for example via a corresponding cable. The connection between the power distributor and the output points (corresponding to individual power paths) preferably has no switches which are actuated in accordance with a detected residual current. Rather, the interruption in accordance with the residual current is carried out using the switching unit.

[0012] Residual current measuring devices are provided between the power distributor and the output points in each case. A residual current measuring device is provided between each output point and the power distributor. This wording means that the residual current measuring devices detect the residual current at the respective potential of the output points and, due to the connection, also the residual current on the associated cable between the output points and the power distributor and at the conductors connected to the output points and the current consumers. In particular, the specific arrangement of the measuring devices is secondary; the measuring devices are rather provided for detecting the residual current of the potential output from the power distributor towards the output points.

[0013] The residual current refers to the difference between the currents of the two conductors (output conductor and return conductor) which lead away from the power distributor (towards the output points). The residual current indicates whether the entire current transmitted by the output conductor is also fed back (transmitted) by the return conductor or whether, due to an insulation problem, an additional current arises which coexists with the current through the return conductor. For example, in the case of an insulation fault, this additional current would lead to a ground potential or earth potential, wherein it cannot be ruled out that this residual current will flow through the user. Therefore, when a residual current above a threshold is detected, the control switching unit carries out the interruption, thus more effectively preventing the voltage output at the output points, i.e. at all output points connected to the power distributor.

[0014] The residual current measuring devices are connected or associated to the switching unit for control purposes or in a signal transmission manner or logically. The switching unit is logically downstream of the measuring devices, wherein this means that certain events detected by the measuring devices cause a change in the state of the switching unit. This applies at least in particular to residual currents above a threshold value, wherein this causes the switching unit to be controlled to be switched off, either via additional logic or directly. The switching unit is set up to isolate the AC source from the power distributor (and / or to isolate the AC source from the DC voltage supply) when one or more of the residual current measuring devices detect a residual current above a specified threshold value. In this case, the switching unit can be designed to be switched off depending on the signals output by the measuring devices. The logic for detecting whether one or more of the detected residual currents is above a threshold value can be provided in the switching unit, in a computing or logic unit between the measuring devices and the switching unit, or can be assigned to a superior control unit.

[0015] The logic is preferably implemented in a logic unit. The logic unit is in particular provided in the switching unit. The logic unit can also be upstream of the switching unit. The switching unit can also be referred to as a circuit breaker or isolation unit. The switching unit is set up to interrupt a power flow, in particular a power flow with a (switching) current strength of at least 10 A, 50 A or 100 A. The logic unit is set up to compare the residual current output by the residual current measuring devices to a threshold value. The logic unit can alternatively be set up to determine whether one of the residual current measuring devices detects a residual current above a threshold value. It can be provided that the residual current measuring devices output a signal representing (for example in digital form) the detected residual current, or that the residual current measuring devices output a signal indicating whether the detected residual current is above a threshold value. In the latter case, the evaluation of whether the detected residual current is above a threshold value is carried out by the residual current measuring devices (or by a measuring device logic assigned to the respective measuring device).

[0016] A comparator can be provided which compares the detected residual current to a 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 upstream of the switching unit (where the measuring devices are connected to this logic unit by means of the unit), or can be provided in the measuring devices or in a respective measuring device logic assigned to the individual measuring devices (or between the measuring devices and the switching unit). The evaluation of whether the measuring devices detect one or more residual current values above a specified threshold value can thus be implemented in a decentralized manner at the measuring devices or in a centralized manner in a consolidated logic at the switching unit.

[0017] The switching unit is opened (or the entire power flow is interrupted) when at least one of the detected residual currents is above the threshold value. Thus, there is an OR ("or") link between the detected residual currents, wherein the result of the OR link determines the switching state of the switching unit. In particular, the OR link exists between the comparison results of the residual currents with the threshold value. The comparison results are binary and indicate whether the threshold value has been exceeded.

[0018] The AC generator can be set to not only open the switching unit when at least one of the residual currents is above the threshold value, but also to deactivate the AC source when this condition is met. In particular, the logic unit can be set to transition the AC source into an inactive state (or to place the AC source into this state) when one or more of the residual current measuring devices detect a residual current above the threshold value. The AC source is in particular designed as a clocked converter (inverter). The AC generator can be set to disable the converter from running when at least one of the residual currents exceeds the threshold value. For this purpose, the logic unit, the switching unit or also the measuring devices can be connected to the AC source or an associated controller for control purposes.

[0019] Preferably, the AC generator is set to first place the AC source into an inactive state and then open the switching unit when at least one of the detected residual currents exceeds the threshold value. As a result, the switching unit is opened in a de-energized state, thereby reducing wear. A controller can be provided which first places the AC source into an inactive state and then opens the switch, wherein the controller additionally opens the switching unit only after a minimum time period has elapsed after placing the AC source into an inactive state.

[0020] The output point is preferably of single-phase design. The output point can comprise contacts for the phase potential and contacts for the neutral conductor potential. In particular, the output point has no protective conductor contacts or, if permitted, has unconnected protective conductor contacts. The output point can be designed as a connection element for a (two-wire) cable to a socket. The socket is in particular designed according to the standards for sockets for power supply networks, for example according to the standard NEMA 1-15 (supplement to Type A plug) or CEE 7 / 16, CEE 7 / 17, CEE 7 / 7, in particular according to a two-pole domestic socket designed in compliance with the corresponding power supply network standards in Japan or the USA. A two-pole socket refers to a socket without a ground contact or with an ungrounded ground contact.

[0021] The switch unit is preferably designed to isolate all poles. In an electromechanical construction, electromagnetic forces act on two contacts isolated from each other, wherein one of the contacts is, for example, assigned to the phase potential and the other contact is assigned to the neutral conductor potential. Alternatively, the two contacts can be assigned to two different phase potentials. Full pole isolation (exclusively) relates to cables which carry current (i.e. carry load current) in the fault-free active operating state.

[0022] The residual current measuring devices preferably each comprise a differential current sensor. A (soft-magnetic) magnetic material can be provided which is wound around two conductors (neutral conductor / phase conductor or first phase conductor / second phase conductor). The magnetic material is encapsulated in a cavity through which the conductors extend. The sensor winding is wound around the magnetic material and not around the conductors, in order to thus detect the total magnetization caused by the two conductors. The sensor winding on the one hand and the conductors on the other hand form the primary and secondary of a transformer. If the currents through the two conductors are identical but mathematically opposite, the sensor winding does not generate a signal, because the magnetic fields of the two conductors cancel each other out. If the two currents are not identical, i.e. a residual current or differential current is generated, the sensor winding generates a signal which corresponds to the difference between the magnetic fields and thus to the difference between the currents. Since the AC generator generates an AC voltage, the sensor winding detects an AC field which represents the differential current or a time derivative thereof. Alternatively, the currents through the two conductors can also be detected by means of shunts or by means of two magnetic sensors, each shunt or magnetic sensor being assigned to one of the conductors. The difference then results from the difference between the two signals output by the two shunts / magnetic sensors.

[0023] The residual current measuring devices can each have communication means in order to output the detected current or differential current value as a signal. In the simplest case, the communication means are simple conductors and corresponding taps, but can also comprise signal amplifiers, analog-digital converters and / or communication devices which are designed in accordance with data transmission standards (Ethernet protocol, CAN, generally wired or wireless transmission protocols, in particular designed for packet or line-switched transmission).

[0024] An AC source can be provided within the bidirectional charging device. In this case, the AC source can have a bidirectional design, in particular for a charging mode, in which power is transferred from the AC side of the AC source to the DC side of the AC source (rectification), and a discharging mode, in which power is transferred from the DC side to the AC side (inversion). Such a charging device can comprise a DC voltage connection (for example for a battery) and an AC voltage connection. Such a charging device is then set to the discharging mode in order to transfer power from the DC voltage connection and convert it into an AC voltage in order to thus power an external load (for example as provided by a procedure as described herein), or to transfer power from the DC voltage connection to an AC voltage power supply grid. Alternatively, the AC source is a dedicated converter, whose DC voltage side is connected to a DC voltage connection (for example for a battery) in order to thus power an external load. An external load refers to a load that is not necessarily part of a vehicle and is designed to be powered by an AC voltage that complies with the standards of an AC voltage power supply grid. A dedicated converter refers to a converter that is not within the power flow range of the charging power. The DC voltage side of the AC source can be connected to a traction battery or to a high-voltage on-board power supply system section of a vehicle, but also to a 48 V or 12 V battery of a vehicle. The vehicle AC generator and thus also the AC source is preferably provided within a vehicle, in particular permanently installed in a vehicle. The AC source is in particular provided as a bidirectional AC charging device (for charging with AC current), wherein the charging device has a DC voltage side that is connected or connectable to a high-voltage battery of an on-board power supply system. The AC voltage side of the AC generator or of the AC source is connected, in particular directly connected, to a switching unit, preferably without using a transformer and / or via a fuse to the switching unit.

[0025] Figure 1 For explaining the operating principle of the embodiments of the AC generator described herein.

[0026] Figure 1 A vehicle F is shown, in which an on-board charging device OBC is provided. In the example shown, a power factor correction filter (reference PFC) and a DC / DC voltage converter (reference DCDC) connected thereto are used as an AC voltage source (reference PFC / DCDC). The AC voltage source PFC / DCDC is powered by a battery B connected to the DC voltage side of the AC source. The battery B (or the associated battery connection) is connected to the power factor correction filter PFC via the DC / DC voltage converter DCDC. 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 AC voltage source PFC / DCDC is connected to the power distributor V via a switching unit SW. A plurality of connection points S1 to S3 is individually connected to the power distributor V. Each of the connection points S1 to S3 is connected to the power distributor V via its own measuring device M1 to M3. The power distributor V thus forms a common node to which the connection points S1 to S3 are connected. The measuring devices M1 to M3 are individually provided so that a residual current detection can be carried out for each connection point (or for the respective potential). The measuring devices M1 to M3 are residual current measuring devices. The residual current measuring devices are provided to detect the respective current difference between the output conductor and the return conductor via which the power distributor V is connected to the plurality of connection points S1 to S3.

[0028] In the example shown, external loads L1 to L3 are connected to the connection points S1 to S3 so that the loads L1 to L3 can receive power from the connection points S1 to S3. This is shown schematically by the arrows between the connection points S1 to S3 and the loads L1 to L3. The respective power flow comes from the power distributor V and leads via the measuring devices M1 to the connection points. This is also shown by the arrows between the power distributor V and the connection points S1 to S3. The connection points S1 to S3 are in particular sockets into which the loads L1 to L3 are plugged, or connection elements that are connected via a cable to sockets into which the loads L1 to L3 are plugged. The loads L1 to L3 are external to the vehicle on-board power supply system, which is shown by the reference EXT. The loads L1 to L3 can be plugged into the connection points S1 to S3 as external loads. The electrical relationships are shown schematically so that the representation of the loads L1 to L3 outside the rectangle that characterizes the vehicle F only indicates that the loads L1 to L3 are provided outside the vehicle on-board power supply system and are only connected to this vehicle on-board power supply system, wherein it is irrelevant whether the loads are physically arranged inside 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, wherein the measurement results come from the measuring devices M and M1 to M3. The arrows from M1 to M3 thus show a 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 provided outside the switching unit SW, for example at the location X. In this case, the logic unit controls the switching unit SW.

[0030] For control purposes, the logic unit is connected to a (bipolar) switch of the switch unit SW. The switch unit is thus arranged to prevent power flow from the AC source to the distributor V. This results in an isolation device in the form of a switch SW that is common to all three power branches shown. If only one of the measuring devices M1 to M3 outputs a detected residual current greater than a specified threshold value to the logic unit L, the switch opens the switch unit. This means that the power flow of all connection points is interrupted. The threshold value represents a limit above which there can be a dangerous contact current. The threshold value can be specified by safety standards.

[0031] If the loads L1 and L2 have an insulation fault, resulting in residual currents that can compensate for one another, only the compensated residual current can be detected at the distributor V. As a result, the fault can not be detected or be falsely ignored. For this reason, separate power paths are provided that are drawn from the distributor V and upstream of this distributor, each of which monitors the residual current by means of a measuring device M1 to M3. This allows the residual current to be monitored separately.

[0032] The vehicle on-board power supply system of the vehicle F shown can operate in such a way that when at least one of the plurality of separate power paths E1, E2, E3 drawn from the distributor V has a residual current that is higher than a specified threshold value, the common power path G that extends between the AC source PFC / DCDC and the distributor V is interrupted. In particular, the residual current is determined by means of the measuring devices M1 to M3. The separate power paths E1 to E3 are drawn at least from the distributor to the output points S1 to S3 and in particular further to the loads L1 to L3 connected to the vehicle via the output points S1 to S3. Preferably, the isolation is carried out by the switch unit SM. The vehicle AC generator is arranged to carry out the method (and in particular comprises the source PFC / DCDC and the distributor as well as the devices M1 to M3 for detecting the residual current within the separate power paths). For the separate power path E1, it is shown that the power path can reach the relevant load L1 from the distributor. This is intended to illustrate that the detection of the residual current involves the connection drawn from the distributor V (towards the output point) and the cable or component connected thereto.

Claims

1. A vehicle AC generator, the vehicle AC generator having an AC source (PFC / DCDC), a switching unit (SW) downstream of the AC source (PFC / DCDC), a plurality of output points (S1-S3), and a power distribution unit (V), the switching unit (SW) being connected to the output points (S1-S3) via the power distribution unit, wherein, A residual current measuring device (M1-M3) is provided between the power distributor (V) and each of these output points (S1-S3), wherein the residual current measuring devices (M1-M3) are connected to the switching unit (SW) in a signal transmission manner, and the switching unit (SW) is configured to isolate the AC source (PFC / DCDC) from the power distributor (V) when one or more of these residual current measuring devices (M1-M3) detect a residual current value higher than a specified threshold.

2. The vehicle AC generator as claimed in claim 1, further comprising a logic unit (L), the logic unit being disposed within the switching unit (SW) or upstream of the switching unit (X), wherein, The logic unit (L) is configured to compare the residual current values ​​output by these residual current measuring devices (M1-M3) with a threshold.

3. The vehicle AC generator as described in claim 2, wherein, The logic unit (L) is configured to deactivate the AC source (PFC / DCDC) when one or more of these residual current measuring devices (M1-M3) detect a residual current value higher than a specified threshold.

4. The vehicle AC generator as described in any one of the preceding claims, wherein, These output points have a single-phase design.

5. The vehicle AC generator as described in any one of the preceding claims, wherein, The switching unit is designed to isolate all poles.

6. The vehicle AC generator as described in any one of the preceding claims, wherein, Each of these residual current measuring devices (M1-M3) includes a differential current sensor.

7. The vehicle AC generator as described in any one of the preceding claims, wherein, The AC source (PFC / DCDC) is a bidirectional on-board charger that is configured in discharge mode to convert the DC voltage on the DC voltage side of the AC source into the AC voltage on the AC voltage side of the AC source, or the bidirectional on-board charger is or is configured as a dedicated converter.

8. A vehicle high-voltage on-board power supply system, the vehicle high-voltage on-board power supply system comprising a vehicle AC generator as described in any one of the preceding claims, wherein, The AC power source (PFC / DCDC) is a bidirectional AC charging device that has a DC voltage side and an AC voltage side. The DC voltage side is connected to the high-voltage battery of the vehicle power system, and the AC voltage side is connected to the switching unit.

9. A method for operating a vehicle on-board power system, wherein, When at least one of the multiple individual power paths (E1, E2, E3) derived from the power distributor (V) has a residual current exceeding a specified threshold, the shared power path (G) between the AC source (PFC / DCDC) and the power distributor (V) is interrupted.

Images