Method for increasing the range of a submerged submarine

Abstract

Method for operating a submarine with an on-board power supply, wherein the submarine has at least one energy storage device, wherein the submarine has a plurality of consumers, wherein the consumers are connected to the on-board power supply, wherein the energy storage device is connected to the on-board power supply via at least one DC-DC converter, wherein the method comprises the following steps: a) Selecting a maximum voltage and a minimum voltage as well as a voltage step size, b) Control of the DC-DC converter so that either the maximum voltage or the minimum voltage is applied to the vehicle electrical system as the vehicle electrical system voltage, c) Measuring the flowing current and calculating the required electrical power, d) If the maximum voltage was selected in step b), reduce the vehicle electrical system voltage by the voltage step size or if the minimum voltage was selected in step b), increase the vehicle electrical system voltage by the voltage step size, e) Measuring the flowing current and calculating the required electrical power as a function of the vehicle electrical system voltage, f) Repeat steps d) and e) until the vehicle electrical system voltage reaches the minimum voltage if the maximum voltage was selected in step b) or the maximum voltage if the minimum voltage was selected in step b), g) Determine the vehicle electrical system voltage with the lowest power output, h) operating the on-board electrical system with the voltage determined in step g), wherein the method is carried out during operation, wherein the submarine has at least one operating mode for suppressing the execution of the method.

Description

[0001] The invention relates to a method for the optimal use of the electrical energy reserves of a submarine and thus for increasing the range when submerged.

[0002] For many decades, the lead-acid battery dominated the energy storage system for submarines and, thanks to many years of experience, remains an important component today. A major advantage is the ability to build very large elementary cells, which offers both performance and weight benefits. Due to the properties of lead-acid batteries, the voltage of the on-board electrical system depends on the charge level of the lead-acid batteries and is therefore subject to strong fluctuations over long periods of time. Accordingly, the consumers on board submarines have been adapted to operate with a wide range of supply voltages in the on-board electrical system. However, new technologies, particularly lithium batteries, are also becoming increasingly popular. In addition to the hope of higher energy density, the very different electrochemical behavior also opens up new optimization possibilities.

[0003] DE 10 2019 216 606 A1, DE 10 2019 216 608 A1, and DE 10 2020 205 327 A1 disclose battery modules particularly for use in submarines. DE 10 2021 200 765 A1 discloses a low-leakage battery module particularly for use in submarines. DE 10 2021 202 491 discloses a method for operating battery modules on board a submarine to minimize magnetic radiation.

[0004] DE 10 2017 009 527 A1 discloses a DC-DC converter for lithium batteries. DE 10 2020 203 469 A1 discloses another DC-DC converter for lithium batteries.

[0005] The use of a DC-DC converter between a battery and the on-board power supply opens up many new possibilities for operating a submarine.

[0006] DE 10 2020 205 050 A1 discloses a method for optimizing energy generation and energy consumption on a watercraft.

[0007] DE 10 2021 202 537 discloses a method for operating a submarine with an on-board electrical system, an energy storage device, and a fuel cell device. DE 10 2021 203 947 discloses a method for determining the aging state of an energy storage device on board a submarine.

[0008] DE 10 2021 210 447 discloses a method for operating an on-board power system of a submarine under high loads. DE 10 2022 205 773 discloses a submarine with two different battery systems and a method for operating the submarine.

[0009] The aim of the invention is to make optimal use of the energy reserves of a submarine and thus increase its range.

[0010] This object is achieved by the method having the features specified in claim 1. Advantageous further developments emerge from the subclaims, the following description, and the drawing.

[0011] The method according to the invention is used to operate a submarine. The submarine has at least one on-board electrical system and at least one energy storage device. For redundancy reasons, a submarine often has at least two on-board electrical systems. On-board electrical systems with different voltage levels are also known. If there are multiple on-board electrical systems, the invention can be applied to each individual on-board electrical system independently of one another. Furthermore, at least two energy storage devices are also common. The energy storage devices can also be constructed, as described in the prior art, from strings, each of which is made up of individual modules, with the strings each being individually and detachably connected to the on-board electrical system. In such a structure, each module usually has a module battery management system, each string a string battery management system, and above this, there is a boat battery management system.The method according to the invention is preferably carried out by or with the boat battery management system. The submarine has a plurality of consumers. The consumers are connected to the on-board electrical system. Due to the large number of different consumers, a theoretical calculation of the optimal voltage for achieving maximum efficiency is practically impossible, especially since consumers can have very different energy consumption over time. Therefore, optimization has so far mainly focused on the traction motor as the largest consumer. However, especially during submerged creep speed, the energy requirement of the traction motor is low, so that the other consumers take center stage in terms of efficiency. The energy storage device is connected to the on-board electrical system via at least one DC-DC converter. This enables the on-board electrical system voltage to be selected independently of the energy storage device's charge level.This is necessary to connect multiple strings independently to the on-board power system, as these typically have different charge levels and therefore different voltages. This is especially important for lithium batteries, as the unit cell cannot be built to any size. Furthermore, DC-DC converters are particularly useful for lithium batteries, as these have a comparatively high short-circuit current, which can be limited by a galvanically isolating DC-DC converter, thus preventing further damage to the submarine in the event of a short circuit.

[0012] The method according to the invention comprises the following steps: a) Selecting a maximum voltage and a minimum voltage as well as a voltage step size, b) Control of the DC-DC converter so that either the maximum voltage or the minimum voltage is applied to the vehicle electrical system as the vehicle electrical system voltage, c) Measuring the flowing current and calculating the required electrical power, d) If the maximum voltage was selected in step b), reduce the vehicle electrical system voltage by the voltage step size or if the minimum voltage was selected in step b), increase the vehicle electrical system voltage by the voltage step size, e) Measuring the flowing current and calculating the required electrical power as a function of the vehicle electrical system voltage, f) Repeat steps d) and e) until the vehicle electrical system voltage reaches the minimum voltage if the maximum voltage was selected in step b), or the maximum voltage if the minimum voltage was selected in step b), g) Determine the vehicle electrical system voltage with the lowest power output, h) Operating the vehicle electrical system with the voltage determined in step g).

[0013] The maximum and minimum voltages are determined in step a) depending on the design of the on-board electrical system. The entire on-board electrical system, including all consumers, is usually designed for a voltage range. This is often a target voltage within a tolerance band around which the voltage may fluctuate. This voltage range is defined at the upper end by a fixed maximum voltage and at the lower end by a specified minimum voltage. For example, it is specified during design that the on-board electrical system and therefore all consumers are designed to operate in this voltage range. This results in a design-related minimum voltage and a design-related maximum voltage. In the simplest embodiment, these values are selected in step a). These values can also be modified in step a).For example, to avoid high line losses, it may be advisable to increase the minimum voltage at high loads, as otherwise the flowing currents would become extremely high. In this case, the minimum voltage can be selected so that the maximum permissible current for the vehicle electrical system is not exceeded at the current flowing power.

[0014] The on-board network voltage is either increased from the minimum voltage in steps equal to the voltage step size to the maximum voltage, and the actual power consumed is recorded at each voltage, or the other way around, from the maximum voltage to the minimum voltage. By using a step size, the process can be limited to a reasonable number of steps and thus carried out within a reasonable timeframe. This allows the voltage at which efficiency is highest and thus the least energy is drawn from the energy storage device to be found purely empirically and without precise knowledge of all consumers. Since the on-board network is then operated at this voltage, the energy reserves are conserved, effectively increasing the range of the submarine.

[0015] In a further embodiment of the invention, the maximum voltage is selected in step b). Thus, the method is carried out from the highest to the lowest voltage. It has been shown that the time required to establish a new steady state is shortest during the voltage changes, allowing the method to be carried out more quickly or precisely.

[0016] In a further embodiment of the invention, a waiting time of 1 to 10 seconds is maintained between step b) and step c) as well as between step d) and step e). The waiting time is preferably 1 to 2 seconds when reducing from the maximum voltage to the minimum voltage, and approximately 5 to 10 seconds when increasing from the minimum voltage to the maximum voltage.

[0017] In a further embodiment of the invention, a minimum voltage of 300 V, preferably 350 V, is selected in step a).

[0018] In a further embodiment of the invention, a maximum voltage of 950 V, preferably 800 V, particularly preferably 650 V, is selected in step a).

[0019] In a further embodiment of the invention, a voltage step size of 5 V to 20 V, in particular 10 V, is selected in step a).

[0020] In a further embodiment of the invention, the method is repeated if the power output changes by more than 10%, preferably by more than 20%, particularly preferably by more than 25%.

[0021] According to the invention, the process is carried out during ongoing operation. Ideally, all other ship systems remain unaffected; they automatically adapt to the changed on-board voltage, allowing the process to run unnoticed in the background.

[0022] In a further embodiment of the invention, the procedure is started manually. This ensures that the procedure is only carried out if carrying out the procedure will not result in any disadvantage for the crew in completing the mission.

[0023] In a further embodiment of the invention, steps a) to g) of the method are performed during test drives under various load conditions, and the resulting vehicle electrical system voltages are stored. During regular operation, the stored values are then used for operation in step h).

[0024] In a further embodiment of the invention, the measured values from step c) and step e) are used for regression analysis. Instead of simply using the voltage with the lowest energy consumption, an optimum can also be found between the voltage values used for the measurement through regression analysis, and the minimum of the found compensation function can then be used as the optimal voltage. For example, and in particular, a Lorentz distribution (including the Voigt function and pseudo-Voigt function) or a sufficiently high-order polynomial, for example, fifth-order, is used as the regression function.

[0025] In a further embodiment of the invention, the states of the consumers are recorded, for example, the amount of energy flowing to the drive motor, the air conditioning system, the electronics, and so on. This data is preferably stored in a database together with the voltage determined in step g). In this case, the method is carried out if there is no suitable database entry for the current state. Otherwise, the stored value for the vehicle electrical system voltage determined in step g) is used in step h) without repeating steps a) to f).

[0026] According to the invention, a submarine has at least one operating mode for suppressing the implementation of the method according to the invention. For example, in a situation where the electromagnetic signature is very important, such as in close proximity to a submarine hunting unit, the change in voltage and the resulting change in currents can create a detectable, variable magnetic field, which would unnecessarily increase the probability of detection. In this operating mode, for example, minimizing the signature is significantly more important than optimizing electrical consumption and thus the range. Accordingly, a suitable operating mode would be the absolute minimization of the signature.

[0027] The method according to the invention is explained in more detail below using an embodiment shown in the drawing. Fig. 1 flowchart

[0028] In Fig. The procedure is shown in Figure 1.

[0029] First, in step a), a maximum voltage of, for example, 650 V and a minimum voltage of 350 V as well as a voltage step size of 10 V are selected.

[0030] In step b) the DC-DC converter is regulated so that the maximum voltage of 650 V is applied.

[0031] In step c) the flowing current is measured and the required electrical power is calculated from the current and voltage.

[0032] In step d), the vehicle electrical system voltage is reduced by a voltage step of 10 V.

[0033] After a waiting time of 1 s, the flowing current is measured in step e) and the required electrical power is calculated as a function of the vehicle electrical system voltage.

[0034] Steps d) and e) are repeated until in step f) the vehicle electrical system voltage has reached the minimum voltage of 350 V.

[0035] From the powers determined in steps c) and e), the on-board network voltage with the lowest power output is determined in step g).

[0036] Subsequently, in step h), the vehicle electrical system is operated at the voltage determined in step g).

Claims

[1] Method for operating a submarine with an on-board power supply, wherein the submarine has at least one energy storage device, wherein the submarine has a plurality of consumers, wherein the consumers are connected to the on-board power supply, wherein the energy storage device is connected to the on-board power supply via at least one DC-DC converter, wherein the method comprises the following steps: a) Selecting a maximum voltage and a minimum voltage as well as a voltage step size, b) Control of the DC-DC converter so that either the maximum voltage or the minimum voltage is applied to the vehicle electrical system as the vehicle electrical system voltage, c) Measuring the flowing current and calculating the required electrical power, d) If the maximum voltage was selected in step b), reduce the vehicle electrical system voltage by the voltage step size or if the minimum voltage was selected in step b), increase the vehicle electrical system voltage by the voltage step size, e) Measuring the flowing current and calculating the required electrical power as a function of the vehicle electrical system voltage, f) Repeat steps d) and e) until the vehicle electrical system voltage reaches the minimum voltage if the maximum voltage was selected in step b) or the maximum voltage if the minimum voltage was selected in step b), g) Determine the vehicle electrical system voltage with the lowest power output, h) operating the on-board electrical system with the voltage determined in step g), wherein the method is carried out during operation, wherein the submarine has at least one operating mode for suppressing the execution of the method. [2] Method according to claim 1,characterized by that the operating mode is the absolute minimization of the submarine's signature. [3] Method according to one of the preceding claims, characterized by that the maximum voltage is selected in step b). [4] Method according to one of the preceding claims, characterized by that a waiting time of 1 to 10 s is waited between step b) and step c) and between step d) and step e). [5] Method according to one of the preceding claims, characterized by that in step a) a minimum voltage of 300 V, preferably 350 V, is selected. [6] Method according to one of the preceding claims, characterized by that in step a) a maximum voltage of 950 V, preferably 800 V, particularly preferably 650 V, is selected. [7] Method according to one of the preceding claims, characterized by that in step a) a voltage step size of 5 V to 20 V, in particular 10 V, is selected. [8] Method according to one of the preceding claims, characterized by that the process is repeated if the power output changes by more than 10%, preferably by more than 20%, particularly preferably by more than 25%. [9] Method according to one of the preceding claims, characterized by that the measured values from step c) and step e) are used for the regression analysis. [10] Method according to claim 9, characterized by that a Lorentz distribution or a polynomial of sufficiently high order, for example fifth order, is used as the regression function.

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