Power supply device, fuel cell vehicle, and method for voltage limitation at power supply device

Abstract

The invention relates to a power supply device (1) for supplying power to at least one electrical consumer (2, 3), the power supply device having a primary power grid (4), in which a first fuel cell device (7) having a first working capacity is present; the power supply device has a voltage converter (13) which connects the primary power grid (4) to a secondary power grid (17) comprising a battery pack (20); and the power supply device has a measuring device (12) for detecting the insulation resistance of the primary power grid (4) and / or the secondary power grid (17). The first fuel cell device (7) in the primary power grid (4) is connected in series with a second fuel cell device (8) having a second working capacity; wherein each of the fuel cell devices (7, 8) is connected in parallel with a bridge circuit (10) comprising a switch (11); and wherein the switches (11) of the bridge circuits (10) can be switched according to the detected insulation resistance. The invention also relates to a fuel cell vehicle and a method for voltage limiting at the power supply device (1).

Description

Technical Field

[0001] The present invention relates to a power supply device for supplying power to at least one electrical consumer, the power supply device having a primary power grid in which a first fuel cell device having a first working capacity exists; the power supply device having a voltage converter, which connects the primary power grid to a secondary power grid including a battery pack; and the power supply device having at least one measuring device for detecting the insulation resistance of the power supply device, in particular the insulation resistance of the primary power grid and / or the secondary power grid. The present invention also relates to a fuel cell vehicle having a power supply device and a method for voltage limiting the power supply device when supplying power to an electrical consumer. Background Art

[0002] Such power supply devices are usually used in fuel cell vehicles, wherein the insulation resistance for such electrically driven vehicles is usually 100 Ohm / Volt (ohms / volt) relative to the highest voltage occurring in order to protect humans from dangerous electric shocks.

[0003] DE 102016219984 A1 shows a power supply device according to the preamble of claim 1 mentioned at the outset. In this case, the insulation resistance of a fuel cell vehicle composed of a mixture of a fuel cell device and a battery is determined by means of a plurality of measuring devices. Depending on the value of the insulation resistance determined, the fuel cell vehicle is placed in an emergency driving mode or even in an idling stop mode in order to prevent dangerous electric shocks.

[0004] US 2008 / 0107933 A1 describes a fuel cell system which sets different numbers of fuel cell stacks to be active or inactive to provide power depending on the load requirements imposed.

[0005] US 2017 / 0162924 A1 describes a fuel cell system which monitors the voltage provided by the fuel cell stack and switches to emergency operation when a limiting voltage of the entire system is exceeded.

[0006] CN 109606203 A describes a method for operating a system formed by a battery and a fuel cell arrangement, which method causes an emergency shutdown in the event of an emergency.

[0007] DE 102013012151 A1 describes an electrical supply device with fuel cells, wherein each fuel cell is assigned its own voltage converter in order to convert the DC voltage of the fuel cells to the voltage level present in the secondary network of the vehicle, in which a battery pack and an electric motor are also present, the latter being coupled to the secondary network via an inverter.

[0008] DE 10010985 A1 describes a system consisting of a parallel circuit of a plurality of fuel cell stacks connected in series. In this case, the individual fuel cell stacks are selectively bridged in order to set the desired operating capacity. Summary of the invention

[0009] The object of the present invention is to specify an electrical supply device, a fuel cell vehicle and a method for voltage limiting which provide increased safety.

[0010] This object is achieved by a power supply device according to the invention, by a fuel cell vehicle according to the invention and by a method according to the invention. Advantageous embodiments of the invention with expedient developments are explained in the following description.

[0011] The power supply device according to the present invention is particularly characterized in that: a first fuel cell device in a primary power grid is connected in series with a second fuel cell device having a second working capacity different from the first working capacity; each of these fuel cell devices is respectively connected in parallel with a bridge circuit including a switch; and the switches of these bridge circuits can be switched according to the detected insulation resistance.

[0012] If two fuel cell devices with different operating capacities are used, it can be ensured that due to the insulation resistance, the voltage is reduced to a level that is not dangerous for humans, because only the fuel cell device with the lower voltage of the fuel cell devices still provides power. In this emergency operation, the dynamic behavior of the still active fuel cell devices, i.e. the setting of the load points adapted to the situation, can be limited. A fuel cell vehicle using this power supply device can still always continue to operate or continue to drive at a reduced power in an emergency driving mode ("limp home"), without the fuel cell vehicle having to be put into a shutdown mode and prevented from continuing to drive.

[0013] In order to limit the voltage of the power supply device, in particular the output voltage of the power supply device, to a value that is not dangerous for humans and thereby increase the insulation resistance to or exceed a predetermined resistance value, it is advantageous if the battery pack in the secondary network is also connected in parallel with a bridge circuit, which includes a switch that can be switched depending on the detected insulation resistance.

[0014] In an advantageous embodiment, it is possible that the voltage converter is formed as a three-port converter for setting the voltage level of the first fuel cell device, the voltage level of the second fuel cell device and the voltage level of the battery pack. The three-port converter can thus ensure that the insulation resistance does not drop below a predetermined resistance value, which could result in an electric shock that is dangerous for humans. To this end, the insulation resistance is first determined by means of a measuring device, and then the maximum voltage possible for the power supply device that is not dangerous for humans is calculated based on the insulation resistance. The individual voltages of the fuel cell device and the battery pack are then set and, if necessary, coordinated with one another so that the maximum voltage value is not exceeded.

[0015] In order to be able to provide power regulation that is usable for different applications, it is also advantageous if, in the primary power grid, there is at least one other fuel cell device, which is connected in series with the remaining fuel cell devices and has a bridge circuit assigned to it, including a switch.

[0016] The advantages, technical effects and advantageous designs described in conjunction with the power supply device according to the present invention are also applicable to the fuel cell vehicle according to the present invention. The fuel cell vehicle is characterized in that, when the insulation resistance is too low, the vehicle can continue to travel at reduced power and an emergency shutdown is avoided.

[0017] The method according to the present invention for limiting the voltage of the above-mentioned power supply device when supplying power to a consumer comprises in particular the following steps:

[0018] A. Detecting the insulation resistance in the primary network and / or in the secondary network by means of a measuring device;

[0019] B. Check whether the insulation resistance is lower than the predetermined resistance value; and

[0020] C. Below a resistance value, one or more switches of the bridge circuit are controlled so that: at least one of the fuel cell devices is bridged and therefore at least partially, preferably completely, set to inactive; and another of the fuel cell devices is not bridged and therefore set to active for providing voltage.

[0021] However, in this method, it is preferably not required that: the first fuel cell device has a first operating capacity; and the second fuel cell device has a second operating capacity different from the first operating capacity; and that the fuel cell device exhibiting a higher operating capacity is bridged below the resistance value.

[0022] In this way, it is ensured that the electrical load is supplied with emergency power at a reduced power, so that an emergency shutdown of the electrical load is avoided.

[0023] It is advantageous that, below the resistance value, the state of charge (SOC) of the battery is reduced, since the voltage of the power supply device is reduced overall in this way.

[0024] If simply reducing the voltage level of the battery pack is not sufficient to increase the insulation resistance to a predetermined resistance value, there is the following possibility: the battery pack in the secondary power grid is also connected in parallel with a bridge circuit, which includes a switch that can be switched depending on the detected insulation resistance; and when the resistance value is below, the battery pack is also bridged and is therefore set to inactive.

[0025] In order to increase the operational safety of the power supply device, it is also advantageous if the voltage converter is designed as a three-port converter which reduces the voltage level of the first fuel cell device, the voltage level of the second fuel cell device and / or the voltage level of the battery below the resistance value. Thus, the three-port converter can set the voltage levels of all components to values ​​that are not dangerous for humans, depending on the existing insulation resistance and the maximum voltage of the power supply device resulting therefrom.

[0026] The features and feature combinations mentioned above in the description and the features and feature combinations mentioned later in the description of the figures and / or shown individually in the figures can be used not only in the respectively described combination but also in other combinations or individually without departing from the scope of protection of the present invention. Therefore, embodiments that are not explicitly shown or described in the drawings, but can be known and produced by the feature combinations selected from the described embodiments, should be regarded as included and disclosed by the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Further advantages, features and details of the invention are apparent from the claims, the following description of preferred embodiments and with reference to the drawings.

[0028] Figure 1 A schematic diagram of a power supply device for supplying power to at least one electrical consumer in the form of a drive device having a drive unit for driving a motor vehicle is shown. DETAILED DESCRIPTION

[0029] exist Figure 1 2 shows a schematic diagram of a power supply device 1 for supplying power to a first electrical consumer 2 and a second electrical consumer 3. Preferably, the power supply device 1 can also supply electrical energy to other electrical consumers that are not shown in more detail.

[0030] The power supply device 1 comprises a primary grid 4, in which a first fuel cell device 7 and a second fuel cell device 8 are present, which are connected in series with each other. The power supply device 1 also has a secondary grid 17, in which a battery pack 20 is present. The battery pack 20 is designed to energize the electrical consumers 2, 3. The primary grid 4 is connected to a voltage converter 13 on the input side, wherein the secondary grid 17 is connected to the voltage converter 13 on the output side in the present case, so that the voltage converter 13 connects the primary grid 4 to the secondary grid 17.

[0031] The electrical consumer 2 comprises a drive unit 22 in the form of an electric motor. This electric motor can usually be operated by means of a three-phase alternating current and is preferably designed as a traction motor of a motor vehicle. Since the primary network 4 and also the secondary network 17 provide high voltage and direct current, the electrical consumer 2 is additionally assigned an inverter 21 which converts the direct current into a three-phase alternating current. In an extension of the electrical consumer 2, the drive unit 22 can also be used as a generator, so that, for example, the energy generated by the drive unit 22 during braking can be fed back to the battery 20 via the inverter 21.

[0032] The electrical consumers 3 can also be connected to the vehicle electrical system consisting of the primary grid 4 and the secondary grid 17. For example, auxiliary devices of the fuel cell system 7, chargers, 12V DC-DC converters, high-voltage heaters, air conditioning compressors, etc. can be considered as electrical consumers 3.

[0033] The power supply device 1 is characterized by a plurality of bridge circuits 10, each of which includes a switch 11. Here, each fuel cell device 7, 8 in the primary power grid 4 is connected in parallel with its own bridge circuit 10, so as to selectively: when the switch 11 is closed, the fuel cell devices 7, 8 are electrically bridged and thereby set to be inactive; or when the switch 11 is open, the relevant fuel cell device 7, 8 is set to be active, so that the fuel cell device provides voltage. In the example shown, the battery pack 20 is also connected in parallel with the bridge circuit 10 with the switch 11, by means of which the battery pack 20 is electrically bridged and thereby set to be inactive when the switch 11 is closed, and by means of which the battery pack 20 is set to be active when the switch 11 is open, so that the battery pack can provide or receive voltage.

[0034] The switch 11 is actuated, for example, by means of a voltage converter 13, which is designed, for example, as a three-port converter, so that it can set the voltage levels of the first fuel cell device 7, the second fuel cell device 8 and the battery 20. However, another controller—separate from the voltage converter 13—can also be present and used for actuating the bridge circuit 10.

[0035] The power supply device 1 comprises a measuring device 12 for detecting the insulation resistance of the primary power grid 4 and / or the secondary power grid 17. Preferably, the measuring device 12 shown detects the insulation resistance of the entire power supply device 1, i.e., thus detects the insulation resistance of the total system. There may be a plurality of measuring devices 12, so that preferably a first measuring device 12 detects the insulation resistance of the primary power grid 4 and a second measuring device detects the insulation resistance of the secondary power grid 17.

[0036] During operation of the power supply device 1, it is ensured that the insulation resistance of the power supply device does not drop below a value that is dangerous for humans. For this reason, the insulation resistance in the primary network 4 and / or in the secondary network 17 is time-controlled or continuously detected by means of the measuring device 12. It is then checked whether the insulation resistance has fallen below a predetermined resistance value, wherein if the resistance value is fallen below, one or more switches of the switches 11 of the bridge circuit 10 are controlled and switched so that the fuel cell device 7, 8 with the higher operating capacity is bridged and thus preferably completely set to inactive, and the fuel cell device 7, 8 with the lower operating capacity is not bridged and is therefore set to active for providing voltage.

[0037] Preferably, when the resistance value is lowered, the state of charge (SOC) of the battery pack 20 is also reduced. If this reduction is not sufficient to achieve the desired insulation value of the system, the bridge circuit 10 assigned to the battery pack 20 can be used. Then, the battery pack 20 is also bridged and is therefore set to inactive, even when the SOC is always lower than the resistance value despite the reduction.

[0038] By means of the corresponding states of the switch 11 in the primary grid 4 and / or the switch 11 in the secondary grid 17, it can be ensured that the insulation resistance is increased to a value that is not dangerous for humans and that the fuel cell vehicle using the power supply device can always still be operated in an emergency driving mode (“limp home” mode). Therefore, it is possible to continue driving. That is, in this way, it is not necessary to put the fuel cell vehicle into a shutdown mode and prevent further driving or further operation.

[0039] The above method and the above power supply device 1 provide high operational safety while having a compact design of all the components involved. This also applies to the drive of a fuel cell vehicle which is supplied with electrical energy using such a power supply device 1 .

[0040] Reference numerals list:

[0041] 1 Power supply device

[0042] 2 Electrical consumption

[0043] 3 (Second) Electrical Consumption

[0044] 4 Primary power grid

[0045] 7. First fuel cell device

[0046] 8. Second fuel cell device

[0047] 10 Bridge Circuit

[0048] 11 Switch

[0049] 12. Measuring device

[0050] 13 Voltage Converter

[0051] 17 Secondary power grid

[0052] 20 Battery Pack

[0053] 21 Inverter

[0054] 22 Drive unit

Claims

1. A power supply device (1) for supplying power to at least one electrical consumer (2, 3), The power supply device comprises a primary power grid (4), in which a first fuel cell device (7) having a first working capacity is present; The power supply device has a voltage converter (13), which connects the primary power grid (4) to a secondary power grid (17) including a battery pack (20); Furthermore, the power supply device has a measuring device (12) for detecting the insulation resistance of the primary power grid (4) and / or the secondary power grid (17). It is characterized in that The first fuel cell device (7) in the primary power grid (4) is connected in series with a second fuel cell device (8) having a second working capacity different from the first working capacity; Each of the fuel cell devices (7, 8) is connected in parallel to a bridge circuit (10) including a switch (11); Furthermore, the switch (11) of the bridge circuit (10) can be switched according to the detected insulation resistance.

2. The power supply device (1) according to claim 1, characterized in that: The battery pack (20) in the secondary power grid (17) is also connected in parallel with a bridge circuit (10), which includes a switch (11) that can be switched according to the detected insulation resistance.

3. The power supply device (1) according to claim 1 or 2, characterized in that: In order to set the voltage level of the first fuel cell device (7), the voltage level of the second fuel cell device (8) and the voltage level of the battery stack (20), the voltage converter (13) is formed as a three-port converter.

4. The power supply device (1) according to claim 1 or 2, characterized in that: In the primary power grid (4), there is at least one other fuel cell device, which is connected in series with the other fuel cell devices (7, 8), and the at least one other fuel cell device has a bridge circuit (10) assigned to the at least one other fuel cell device and includes a switch (11).

5. A fuel cell vehicle comprising the power supply device (1) according to any one of claims 1 to 4.

6. A method for voltage limiting of a power supply device (1) according to any one of claims 1 to 4 when supplying power to electrical consumers (2, 3), The power supply device comprises a primary power grid (4), in which a first fuel cell device (7) and a second fuel cell device (8) are present, wherein the fuel cell devices (7, 8) in the primary power grid (4) are connected in series with each other, and wherein the fuel cell devices (7, 8) in the primary power grid (4) are respectively connected in parallel with a bridge circuit (10) comprising a switch (11), The power supply device comprises a voltage converter (13), which connects the primary power grid (4) to a secondary power grid (17) comprising a battery pack (20). Furthermore, the power supply device has a measuring device (12) for detecting the insulation resistance of the primary power grid (4) and / or the secondary power grid (17). The method comprises the following steps: A. detecting the insulation resistance in the primary network (4) and / or in the secondary network (17) by means of the measuring device (12); B. Check whether the insulation resistance is lower than a predetermined resistance value; and C. below the resistance value, controlling one or more switches (11) of the bridge circuit (10) so that: at least one of the fuel cell devices (7, 8) is bridged and thus at least partially set to be inactive; and another of the fuel cell devices (7, 8) is not bridged and thus is set to be active in order to provide a voltage.

7. The method according to claim 6, characterized in that In step C, one or more switches (11) of the bridge circuit (10) are controlled below the resistance value so that: at least one of the fuel cell devices (7, 8) is bridged and is therefore completely set to inactive; and another of the fuel cell devices (7, 8) is not bridged and is therefore set to active for providing voltage.

8. The method according to claim 6, characterized in that The first operating capacity is different from the second operating capacity; and below a resistance value, the fuel cell device (7, 8) having the higher operating capacity is bridged.

9. The method according to any one of claims 6 to 8, characterized in that When the resistance value is lower than the resistance value, the state of charge (SOC) of the battery pack (20) is reduced.

10. The method according to claim 9, characterized in that The battery pack (20) in the secondary power grid (17) is also connected in parallel with a bridge circuit (10), which includes a switch (11) that can be switched according to the detected insulation resistance; and the battery pack (20) is also bridged when the resistance value is below the value and is therefore set to be inactive.

11. The method according to any one of claims 6 to 8, characterized in that The voltage converter (13) is formed as a three-port converter; the three-port converter reduces the voltage level of the first fuel cell device (7), the voltage level of the second fuel cell device (8) and / or the voltage level of the battery pack (20) below a resistance value.

Images