Submarine with a situation-independent power supply for a string battery management system

Abstract

A submarine (10) with at least one energy storage device and an on-board power supply system (90), wherein the energy storage device comprises lithium accumulators, wherein the energy storage device comprises at least a first string (20) and a second string (22), wherein the first string (20) comprises a first string network (80) and the second string (22) comprises a second string network (80), wherein the first string (20) comprises a first string battery management system (50) and the second string (22) comprises a second string battery management system (50), wherein the first string (20) is connected to the on-board power supply system (90) via a first DC-DC converter (40), wherein the second string (22) is connected to the on-board power supply system (90) via a second DC-DC converter (40), wherein the first DC-DC converter (40) and the second DC-DC converter (40) are each bidirectional and galvanically isolating, characterized inthat the first battery management system (50) and the second battery management system (50) each have a first power supply unit (60) and a second power supply unit (70), wherein the first power supply unit (60) and the second power supply unit (70) are each designed to be galvanically isolating, wherein the first power supply unit (60) is arranged between the string network (80) and the DC-DC converter (40) and the second power supply unit (70) is arranged between the vehicle electrical system (90) and the DC-DC converter (40), wherein the first power supply unit (60) is connected to the first DC-DC converter (40) via a first device supply network, wherein the first DC-DC converter (40) and the first string battery management system (50) are connected to the first device supply network, wherein the second power supply unit (70) is connected to the second DC-DC converter (40) via a second device supply network,wherein the second DC-DC converter (40) and the second string battery management system (50) are connected to the second device supply network.,

Description

[0001] The invention relates to a submarine with modules composed of lithium accumulators as energy storage devices and a string battery management system.

[0002] Lithium-based batteries are becoming increasingly attractive, for example due to their high energy density. However, especially for large energy storage systems, there are two fundamental differences compared to lead-sulfuric acid batteries, for example. Firstly, the individual cells cannot simply be enlarged at will. This means that numerous batteries are regularly combined to form a larger module. Secondly, these batteries are particularly susceptible to the problem of thermal runaway. Since this also produces a large amount of gas, this poses a significant risk, especially in critical environments, as has been demonstrated, for example, with batteries in aircraft.

[0003] The smaller unit cells allow the modules to deliver a comparatively high voltage. Each string delivers the full voltage to the on-board power system and is electrically isolated from the submarine's on-board power system via a DC-DC converter. The strings are therefore independent of each other and can be switched on or off depending on the load.

[0004] For example, a submarine typically has an energy storage device comprising approximately 10 to 50 strings, each string comprising approximately 4 to 10 modules. A module may, for example, comprise 20 to 500 batteries.

[0005] To ensure the safe operation of lithium batteries and their maximum service life, battery management systems are used. These systems monitor charging and discharging processes, particularly to prevent overcharging or deep discharging. Temperatures are also typically recorded to deactivate the system in the event of a malfunction (thermal runaway).

[0006] A submarine uses a cascaded system of battery management systems for a variety of reasons. A boat battery management system provides overall monitoring and interfaces to other boat systems. Each string also has its own string battery management system. This also controls the DC-DC converter, which supplies energy to the on-board power system or draws energy from the on-board power system for charging. Furthermore, the modules can have individual module battery management systems, which then perform monitoring at the cell level, particularly voltage and temperature, which are precisely monitored at this lowest level. These various battery management systems are usually hierarchically interconnected to ensure data exchange.

[0007] A DC-DC converter for lithium batteries is known from DE 10 2017 009 527 A1.

[0008] From DE 10 2017 002 112 A1 a submarine and a method for operating a propulsion system of a submarine are known.

[0009] A propulsion system for a submarine is known from DE 10 2014 109 092 A1.

[0010] From DE 10 2014 204 473 A1 a device and a method for wiring a battery management system are known.

[0011] From DE 10 2016 213 573 A1 a high-voltage battery, a method for operating a high-voltage battery and a vehicle are known.

[0012] A battery management system for a vehicle is known from US 10 263 438 B2.

[0013] From DE 10 2014 201 059 A1 a supply circuit for the redundant supply of a battery control and a battery with a redundantly supplied battery control are known.

[0014] On a submarine, certain conditions occur that are less likely to occur, especially in land-based applications. On the one hand, a submarine may have to be started with the power off, for example, after an overhaul. On the other hand, especially in a combat situation, it may be necessary to largely discharge at least individual strands in order to, for example, still provide sufficient energy to escape from a dangerous situation and surface. Even in such a situation, it must be possible to recharge the batteries.

[0015] The object of the invention is to provide a string battery management system that ensures the operational capability of the accumulators under all possible situations that may occur on board a submarine.

[0016] This object is achieved by the submarine having the features specified in claim 1. Advantageous further developments emerge from the subclaims, the following description and the drawing.

[0017] The submarine according to the invention has at least one energy storage device and an on-board electrical system. The energy storage device has lithium batteries. The energy storage device further has at least a first string and a second string. Typically, the energy storage device has 10 to 50 strings, the other strings are constructed in the same way as the first string and the second string. The first string has a first string network and the second string has a second string network. The electrical energy from the individual lithium cells is brought together via the string network and fed to the DC-DC converter and via the DC-DC converter into the on-board electrical system, or in the opposite direction when the lithium cells are charged. The first string has a first string battery management system and the second string has a second string battery management system.The first line is connected to the vehicle electrical system via a first DC-DC converter, and the second line is connected to the vehicle electrical system via a second DC-DC converter. The first DC-DC converter and the second DC-DC converter are each bidirectional and galvanically isolated. This bidirectional design is necessary so that the lithium batteries can be charged and discharged. Galvanic isolation allows the networks to be separated, which is necessary for simultaneous insulation monitoring of both networks. It also prevents a short circuit in the vehicle electrical system from demanding excessive power from the lithium batteries, which could then damage them.

[0018] The basic functionality is that on one side of the DC-DC converter there are lithium batteries that can absorb and release energy. On the other side of the DC-DC converter there is an on-board electrical system to which consumers, such as the traction motor, are connected. Energy is supplied to the consumers via the on-board electrical system. Furthermore, at least one energy generator is usually connected to the on-board electrical system, for example a diesel generator and / or a fuel cell. The generator can supply energy via the on-board electrical system directly to a consumer and / or to the energy storage unit in order to charge it. Likewise, the energy generator and energy storage unit can also supply energy simultaneously and supply it to one or more consumers. However, the lithium batteries are not connected directly to the on-board electrical system, but via the DC-DC converter.Furthermore, each string has a string battery management system that controls and monitors the system.

[0019] Since the DC-DC converters are designed to enable bidirectional voltage conversion, active control is necessary to regulate the direction of energy flow. These logic components are controlled by the string battery management system.

[0020] According to the invention, the energy storage device has a first power supply and a second power supply for each string. The first power supply and the second power supply are each designed to be galvanically isolated. This is necessary to ensure the galvanic isolation between the string network and the on-board power supply, which is provided by the DC-DC converter. The first power supply is arranged between the string network and the DC-DC converter in each string, and the second power supply is arranged between the on-board power supply and the DC-DC converter in each string.

[0021] According to the invention, the first power supply unit is connected to the DC-DC converter via a first device supply network, wherein the DC-DC converter and the string battery management system are connected to the first device supply network.

[0022] The same applies to the second side: According to the invention, the second power supply unit is connected to the DC-DC converter via a second device supply network, wherein the DC-DC converter and the string battery management system are connected to the second device supply network.

[0023] In a further development, the first device supply network and the second device supply network are electrically connected to each other.

[0024] This arrangement increases the complexity, the number of components and therefore also the weight and size. However, these disadvantages are offset by two advantages that are important for a submarine. Firstly, a completely switched off submarine, with no voltage applied to the on-board power supply, can be supplied with energy because the string network can supply the necessary energy to the DC-DC converter via the first power supply. At the same time, even if the string is empty and can no longer provide sufficient electrical energy, it can be charged via the on-board power supply because in this case the on-board power supply can supply the DC-DC converter with energy via the second power supply. Another advantage is increased redundancy during normal operation, which is always a positive feature in military applications, especially on submarines. If one power supply fails, the DC-DC converter and thus the entire lithium battery string remains fully operational.

[0025] The DC-DC converter, also called a DC / DC controller or DC-DC converter, electrically connects the lithium battery to the vehicle electrical system. The electrical circuit arrangement of a DC-DC converter is well known and can be implemented using various known circuit topologies. In particular, a topology is chosen that results in galvanic isolation of the battery from the vehicle electrical system. Examples of suitable topologies are flyback converters, single-ended forward converters, push-pull forward converters, or resonant converters. For example, in a push-pull forward converter, the direct current is first converted into alternating current, transformed, and then converted back into direct current. In order to be able to discharge and charge the lithium battery, the DC-DC converter is preferably designed symmetrically. The DC-DC converter adapts the voltage provided by the lithium battery to the voltage of the vehicle electrical system.An example of such a DC-DC converter can be found in DE 10 2017 009 527 A1 in . Fig. 4 and the associated description. The DC-DC converter shown in the example has two H-bridges, each with four MOSFETs. For isolation, all eight MOSFETs are preferably non-conductive. During operation, i.e. when the load switch is electrically conductive, two diagonally opposite MOSFETs are always conductive and the other two diagonally opposite are non-conductive, with this circuit constantly alternating. This continuous circuit ensures the conversion of the direct current into alternating current, which is then transformed and converted back into direct current on the other side in an analog manner. The symmetrical design allows current to flow in both directions to enable both charging and discharging of the first accumulator.

[0026] In a further embodiment, the energy storage device has a third power supply and a fourth power supply for each string. The third power supply and the fourth power supply can optionally each be galvanically isolated. The third power supply is arranged between the string network and the string battery management system for each string, and the fourth power supply is arranged between the on-board network and the string battery management system for each string.

[0027] In a further embodiment of the invention, the first power supplies and the second power supplies are of identical construction.

[0028] In a further embodiment of the invention, the string battery management system is connected to the first power supply and the second power supply in a non-switchable / non-separable manner. While any electrical connection can be severed by severing the cable, in the simplest case, cutting it, no switching element is provided in this embodiment. This means that as soon as at least the string network or the on-board network is live, the string battery management system is automatically activated. This makes it possible to directly control the string battery management system via a data line using a boat battery management system without first activating a power supply.

[0029] In a further embodiment of the invention, the string battery management system has a control module for the DC-DC converter. Using the control module, the standby battery management system specifies, for example, current or voltage setpoints to the DC-DC converter. This is necessary, for example, when load surges occur in the vehicle electrical system or when the string needs to be switched from supply mode to charging mode.

[0030] The submarine according to the invention is explained in more detail below using an embodiment shown in the drawing. Fig. 1 Schematic sketch of a first circuit Fig. 2 Schematic sketch of a second circuit Fig. 3 Schematic sketch of a third circuit Fig. 4 Schematic diagram of a fourth circuit

[0031] In Fig. Figure 1 shows a rough outline of the structure of a submarine 10 according to the invention in a first circuit configuration. The submarine 10 has a first line 20, a second line 22, and a third line 24. Typically, a submarine 10 would have even more lines, but as already apparent, the lines 20, 22, and 24 are constructed identically, so that more lines here merely represent a duplication of what is shown. The submarine 10 has an on-board electrical system 90. The consumers, for example, a traction motor, but also energy generators, for example, a diesel generator and a fuel cell, are connected to the on-board electrical system 90.

[0032] In the example shown, each string 20, 22, 24 has five modules 30. Here, too, the number can vary without changing the structure. The modules 30 are connected to a DC-DC converter 40 via a string network 80. The DC-DC converter 40 galvanically isolates the string network 80 from the on-board electrical system 90.

[0033] The DC-DC converter 40 is controlled by a string battery management system 50. For power supply, the string battery management system 50 is connected to a first power supply 60 and a second power supply 70. The first power supply 60 is electrically isolated from the string network 80, and the second power supply 70 is electrically isolated from the vehicle electrical system 90.

[0034] In Fig. 2 shows a second circuit which differs from the first in Fig. 1 in that the string battery management system 50 and the DC-DC converter 40 are connected to the first power supply unit 60 via a first device supply network 100 and to the second power supply unit 70 via a second device supply network 110.

[0035] Fig. 3 shows a third circuit, which differs from the first in Fig. 1 in that the DC-DC converter 40 is connected to the first power supply 60 and the second power supply 70. The string battery management system 50 is connected to the DC-DC converter 40 and is supplied with energy by it.

[0036] Fig. 4 shows a fourth circuit, which differs from the first in Fig.1 in that the string battery management system 50 and the DC-DC converter 40 are connected to the first power supply unit 60 and the second power supply unit 70 via a common device supply network. Reference symbol 10 submarines 20 first strand 22 second strand 24 third strand 30 Module 40 DC-DC converters 50-string battery management system 60 first power supply 70 second power supply 80 strand network 90 On-board network 100 first device supply network 110 second device supply network

Claims

[1] A submarine (10) having at least one energy storage device and an on-board power supply system (90), wherein the energy storage device comprises lithium accumulators, wherein the energy storage device comprises at least a first string (20) and a second string (22), wherein the first string (20) comprises a first string network (80) and the second string (22) comprises a second string network (80), wherein the first string (20) comprises a first string battery management system (50) and the second string (22) comprises a second string battery management system (50), wherein the first string (20) is connected to the on-board power supply system (90) via a first DC-DC converter (40), wherein the second string (22) is connected to the on-board power supply system (90) via a second DC-DC converter (40), wherein the first DC-DC converter (40) and the second DC-DC converter (40) are each bidirectional and galvanically isolating, characterized bythat the first battery management system (50) and the second battery management system (50) each have a first power supply (60) and a second power supply (70), wherein the first power supply (60) and the second power supply (70) are each designed to be galvanically isolated, wherein the first power supply (60) is arranged between the string network (80) and the DC-DC converter (40) and the second power supply (70) is arranged between the on-board network (90) and the DC-DC converter (40), wherein the first power supply (60) is connected to the first DC-DC converter (40) via a first device supply network, wherein the first DC-DC converter (40) and the first string battery management system (50) are connected to the first device supply network, wherein the second power supply (70) is connected to the second DC-DC converter (40) via a second device supply network,wherein the second DC-DC converter (40) and the second string battery management system (50) are connected to the second device supply network., [2] Submarine (10) according to claim 1, characterized by that the first power supplies (60) and the second power supplies (70) are of identical design. [3] Submarine (10) according to one of the preceding claims, characterized by that the string battery management system (50) is not switchably or separably connected to the first power supply (60) and the second power supply (70). [4] Submarine (10) according to one of the preceding claims, characterized by that the string battery management system (50) has the control for the DC-DC converter (40).

Images