Ship electric propulsion system

Abstract

The invention discloses a ship electric propulsion system which comprises at least two ship electric propulsion subsystems, and each ship electric propulsion subsystem comprises a first two-way controller, a second two-way controller, a main propulsion motor and an alternating current output module which are electrically connected through an alternating current switch group. The direct-current power supply is electrically connected with the first two-way controller and the second two-way controller; the following functions are realized through the alternating current switch group: the first bidirectional controller controls the operation of the main propulsion motor; the second two-way controller supplies the alternating current to the ship through the alternating current output module; the first bidirectional controller and the second bidirectional controller charge the direct current power supply at the same time; when the first two-way controller breaks down, the second two-way controller controls the main propulsion motor to operate; wherein the second two-way controllers of the ship electric propulsion subsystems are standby for each other. According to the invention, high-redundancy propulsion control can be realized, energy waste is reduced, basic power of the ship is guaranteed, and sailing safety of open seas and complex water areas is remarkably improved.

Description

Technical Field

[0001] This invention belongs to the field of marine power technology, and more specifically, relates to a marine electric propulsion system. Background Technology

[0002] With the deepening of global low-carbon and environmental protection concepts and the development of new energy technologies, ship propulsion systems are transforming from traditional internal combustion engine drive to electrification and low-carbonization. Electric propulsion systems, due to their advantages in environmental friendliness, economy, and power control flexibility, have become the core direction for ship propulsion upgrades. However, existing ship electric propulsion and energy management technologies still face the following key technical challenges:

[0003] I. Limitations of Traditional Power Systems and Early Electric Propulsion Systems

[0004] 1. Environmental protection and energy consumption issues: Traditional ship power relies on internal combustion engines such as diesel engines and gas turbines, which emit large amounts of nitrogen oxides, sulfides and particulate matter during operation; at the same time, internal combustion engines have low thermal efficiency and serious energy waste.

[0005] 2. Structural redundancy of AC propulsion systems: Early ships mostly used AC systems for electric propulsion, which required a large number of rectifiers and inverters to convert electrical energy. This not only increased the complexity of the system and the risk of failure, but also reduced the overall efficiency due to device losses, and harmonic pollution had an adverse effect on the stability of the ship's power grid.

[0006] II. Shortcomings in the Reliability and Safety of Existing Electric Propulsion Systems for New Energy Ships

[0007] 1. Insufficient redundancy design in the propulsion system: Although the current mainstream dual electric propulsion system can maintain operation when one system fails, the remaining system can only provide partial power, resulting in a significant drop in speed. If both systems fail simultaneously, the ship will completely lose power, posing a serious threat to navigation safety, especially in difficult rescue scenarios such as the open sea and complex waters.

[0008] 2. Limited energy supply and storage utilization:

[0009] The coverage of charging piles in infrastructure such as ports and docks is low. New energy ships rely on their own charging modules, but these have low power and slow charging speed. Furthermore, the configuration of multiple modules will occupy valuable space on the ship, increase procurement costs, and restrict the ship's range and operational efficiency.

[0010] The energy storage potential of large-capacity battery packs on ships has not been fully utilized: existing household inverters have limited power or are designed for off-grid use, which cannot supply power to high-power electrical appliances on shore or feed excess power back to the shore grid, resulting in idle battery energy storage resources and failing to form a value-added model of "ship-shore" energy interaction.

[0011] To address the aforementioned issues, there is an urgent need to develop a highly reliable, efficient, and energy-efficient DC electric propulsion and energy management system for ships. This system should optimize redundant control logic, improve the coordination efficiency of battery packs and inverters, and expand energy storage application scenarios. This will solve technical bottlenecks such as high pollution from traditional power systems, insufficient reliability of existing electric propulsion systems, and limited energy supply and utilization, thereby promoting the large-scale application and industrial development of new energy ships.

[0012] The information disclosed in the background section of this invention is intended only to enhance the understanding of the general background of this invention, and should not be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art. Summary of the Invention

[0013] The purpose of this invention is to propose a ship electric propulsion system that solves the problems of high pollution from traditional power, insufficient reliability of existing electric propulsion, and limited energy supply and utilization. It achieves high redundancy propulsion control, reduces energy waste, ensures basic ship power, and significantly improves navigation safety in the open sea and complex waters.

[0014] To achieve the above objectives, the present invention proposes a ship electric propulsion system, comprising:

[0015] At least two ship electric propulsion subsystems, each of which includes:

[0016] DC power supply, first bidirectional controller, second bidirectional controller, main propulsion motor, AC output module and AC switch assembly;

[0017] The first bidirectional controller, the second bidirectional controller, the main propulsion motor, and the AC output module are electrically connected via an AC switch group.

[0018] The DC power supply is electrically connected to the first bidirectional controller and the second bidirectional controller;

[0019] The following functions can be achieved by changing the connection relationship between the first bidirectional controller, the second bidirectional controller, the main propulsion motor, and the AC output module using an AC switch group:

[0020] The first bidirectional controller converts the DC power output from the DC power supply into AC power to supply the main propulsion motor and control its operation.

[0021] The second bidirectional controller converts the DC power output from the DC power supply into AC power and sends it to the AC output module, thereby providing AC power to the ship's loads.

[0022] The first bidirectional controller and the second bidirectional controller convert the AC power supplied by the AC output module into DC power to supply the DC power supply for charging.

[0023] When the first bidirectional controller fails, the second bidirectional controller converts the DC power output from the DC power supply into AC power to supply the main propulsion motor in order to control the operation of the main propulsion motor.

[0024] The second bidirectional controllers of each ship's electric propulsion subsystem serve as backups for each other.

[0025] Optionally, the AC switch group includes:

[0026] The first AC switch is connected at one end to the first bidirectional controller and at the other end to the main propulsion motor;

[0027] The second AC switch is connected at one end to the second bidirectional controller and at the other end to the main propulsion motor;

[0028] The third AC switch is connected at one end to the second bidirectional controller and at the other end to the AC output module;

[0029] The fourth AC switch is connected at one end to the first bidirectional controller and at the other end to the second bidirectional controller.

[0030] Optionally, the AC output module includes:

[0031] Isolation transformer, fifth AC switch and AC busbar;

[0032] One end of the isolation transformer is connected to the third AC switch, and the other end is connected to the AC busbar;

[0033] One end of the fifth AC switch is connected to the AC bus. The fifth AC switch is used to connect the AC bus of the shore power supply / shore power equipment / adjacent ship electric propulsion subsystem.

[0034] The AC busbar is electrically connected to the ship's AC load.

[0035] Optionally, each of the ship's electric propulsion subsystems further includes:

[0036] The DC bus connects the DC power supply to the first bidirectional controller and the second bidirectional controller.

[0037] Optionally, the DC power supply includes:

[0038] Multiple battery packs.

[0039] Optionally, each of the ship's electric propulsion subsystems further includes:

[0040] Multiple first DC switches, each corresponding to a battery pack, have one end connected to the DC bus and the other end connected to the corresponding battery pack.

[0041] Optionally, it also includes:

[0042] The second DC switch is located between the DC buses of adjacent ship electric propulsion subsystems.

[0043] Optionally, when the ship is sailing normally, the control strategy of the ship's electric propulsion subsystem is as follows:

[0044] S1. Determine whether the SOC of the DC power supply is greater than the set threshold. If not, shut down the main propulsion motor and the ship's AC load, and disconnect all switches. If yes, compare the SOC of each battery pack, close the first DC switch corresponding to the battery pack with the highest SOC, and open the first DC switch corresponding to the other battery packs. Then execute S2.

[0045] S2. Determine if the second bidirectional controller is faulty. If not, control the third AC switch to close and control the third AC switch of other ship electric propulsion subsystems to open and the fifth AC switch to close, so that the second bidirectional controller supplies power to the ship's AC load. Execute S4. If yes, control the third AC switch to open and execute S3.

[0046] S3. Determine if there is a fault in the second bidirectional controller of the adjacent ship's electric propulsion subsystem. If not, control the second bidirectional controller to close, and control the third AC switch and the fifth AC switch of the adjacent ship's electric propulsion subsystem to close, and the second bidirectional controller to open, so that the second bidirectional controller of the adjacent ship's electric propulsion subsystem supplies power to the ship's AC load. Execute S4. If yes, control the third AC switch of the adjacent ship's electric propulsion subsystem to open, and execute S4.

[0047] S4. Determine if there is a fault in the first bidirectional controller. If not, proceed to S5; if yes, proceed to S6.

[0048] S5. Control the first AC switch to close and the second AC switch to open, and control the main propulsion motor to run by the first bidirectional controller, then return to S1;

[0049] S6. Determine if there is a fault in the second bidirectional controller. If yes, control the main propulsion motor to shut down and return to S1; otherwise, execute S7.

[0050] S7. Determine whether the second bidirectional controller controls the main propulsion motor to run. If yes, execute S9; if no, control the second bidirectional controller to stop supplying power to the ship's AC load, then control the third AC switch to open and the second AC switch to close, and execute S8.

[0051] S8. Determine if there is a fault in the second bidirectional controller of the adjacent ship's electric propulsion subsystem. If yes, control the third AC switch of the adjacent ship's electric propulsion subsystem to open and execute S9. If no, control the third AC switch and the fifth AC switch of the adjacent ship's electric propulsion subsystem to close, control the second bidirectional controller of the adjacent ship's electric propulsion subsystem to open, and supply power to the ship's AC load by the second bidirectional controller of the adjacent ship's electric propulsion subsystem and execute S9.

[0052] S9. The main propulsion motor is controlled by the second bidirectional controller to execute S10;

[0053] S10. Determine if the first bidirectional controller is faulty. If so, return to S5; otherwise, control the second bidirectional controller to shut down and execute S5.

[0054] Optionally, when the ship is docked to charge the battery pack, the control strategy of the ship's electric propulsion subsystem is as follows:

[0055] The fifth AC switch is connected to the shore power supply / adjacent ship electric propulsion subsystem, and the first AC switch is opened, the second AC switch is opened, the third AC switch is closed, the fourth AC switch is closed, the fifth AC switch is closed, and the first DC switch corresponding to the lowest SOC battery pack is closed. At this time, the first bidirectional controller and the second bidirectional controller convert the AC power supplied by the shore power supply to the AC output module into DC power to provide the corresponding battery pack for charging.

[0056] Optionally, when the ship is docked and discharging into shore-based electrical equipment or the power grid, the control strategy of the ship's electric propulsion subsystem is as follows:

[0057] The fifth AC switch is connected to shore-based electrical equipment or the power grid / adjacent ship electric propulsion subsystem, and controls the first AC switch to open, the second AC switch to open, the third AC switch to close, the fourth AC switch to close, the fifth AC switch to close, and the first DC switch to close. At this time, the first bidirectional controller and the second bidirectional controller convert the DC power output from the DC power supply into AC power and send it to the AC output module, thereby providing it to the shore-based electrical equipment or the power grid.

[0058] The beneficial effects of this invention are as follows: This system includes at least two marine electric propulsion subsystems, and the second bidirectional controllers of each subsystem serve as backups for each other. Furthermore, if the first bidirectional controller in a single subsystem fails, the second bidirectional controller can take over its function of controlling the main propulsion motor. This dual backup design greatly reduces the risk of system paralysis due to the failure of a single component, ensuring stable propulsion and power supply even in complex navigation environments, significantly improving the safety of ship navigation. The system flexibly changes the connection relationships of each component through an AC switch group, enabling the first and second bidirectional controllers to convert the AC output module's AC power into DC power to charge the DC power supply, achieving energy recycling. This not only reduces energy waste but also allows for reasonable adjustment of energy distribution during ship load fluctuations, improving overall energy efficiency and reducing the energy consumption costs of ship operation. With the switching function of the AC switch group, the system can flexibly realize multiple functions such as main propulsion motor drive, ship AC load power supply, and DC power charging according to actual needs. This high flexibility allows the system to adapt to different navigation conditions and load requirements. Because the system has a backup function, when a bidirectional controller fails, it can be switched to the backup controller in a timely manner, avoiding losses caused by downtime for maintenance and reducing the cost of emergency repairs. In addition, flexible energy distribution and operation modes can prevent equipment from operating at full load or in an unreasonable state for a long time, which helps to extend the service life of each component and further reduces the overall operation and maintenance costs of the ship.

[0059] The system of the present invention has other features and advantages that will be apparent from or will be set forth in detail in the accompanying drawings and following detailed description, which together serve to explain the particular principles of the invention. Attached Figure Description

[0060] The above and other objects, features and advantages of the present invention will become more apparent from the accompanying drawings, in which like reference numerals generally denote like parts.

[0061] Figure 1 A schematic diagram of a ship electric propulsion system according to Embodiment 1 is shown.

[0062] Figure 2 A schematic diagram of a ship electric propulsion system according to Embodiment 2 is shown.

[0063] Figure 3 A flowchart illustrating the steps of a control strategy for a ship electric propulsion system during normal ship navigation, according to Embodiment 2, is shown. Detailed Implementation

[0064] The invention will now be described in more detail with reference to the accompanying drawings. While preferred embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0065] Example 1

[0066] like Figure 1 As shown, this embodiment provides a ship electric propulsion system, including:

[0067] At least two ship electric propulsion subsystems, each ship electric propulsion subsystem comprising:

[0068] DC power supply, first bidirectional controller, second bidirectional controller, main propulsion motor, AC output module and AC switch assembly;

[0069] The first bidirectional controller, the second bidirectional controller, the main propulsion motor, and the AC output module are electrically connected via an AC switch group.

[0070] The DC power supply is electrically connected to the first bidirectional controller and the second bidirectional controller;

[0071] The following functions can be achieved by changing the connection relationship between the first bidirectional controller, the second bidirectional controller, the main propulsion motor, and the AC output module using an AC switch group:

[0072] The first bidirectional controller converts the DC power output from the DC power supply into AC power to supply the main propulsion motor and control its operation.

[0073] The second bidirectional controller converts the DC power output from the DC power supply into AC power and sends it to the AC output module, thereby providing AC power to the ship's loads.

[0074] The first bidirectional controller and the second bidirectional controller convert the AC power supplied by the AC output module into DC power to supply the DC power supply for charging.

[0075] When the first bidirectional controller fails, the second bidirectional controller converts the DC power output from the DC power supply into AC power to supply the main propulsion motor in order to control the operation of the main propulsion motor.

[0076] The second bidirectional controllers of each ship's electric propulsion subsystem serve as backups for each other.

[0077] Specifically, the ship electric propulsion system of this embodiment consists of at least two ship electric propulsion subsystems. Each subsystem includes six core components: a DC power supply, a first bidirectional controller, a second bidirectional controller, a main propulsion motor, an AC output module, and an AC switch group. The DC power supply, as the energy hub, is directly electrically connected to both the first and second bidirectional controllers, providing a stable DC power input and serving as the energy foundation for the entire subsystem's operation. The DC power supply provides DC power to the system (e.g., multiple battery packs supporting charge-discharge cycles); the first bidirectional controller is the primary power controller, responsible for converting DC power into AC power to drive the main propulsion motor; the second bidirectional controller is a daytime / standby controller, balancing AC load power supply and main propulsion redundancy; the main propulsion motor is the ship's power output device (e.g., a propeller-driven motor); the AC output module is an interface unit connecting onboard AC loads, shore power, and adjacent subsystems; and the AC switch group consists of multiple AC switches, which change the connection relationships of equipment through on / off combinations to achieve function switching.

[0078] The connections between the first bidirectional controller, the second bidirectional controller, the main propulsion motor, and the AC output module are not fixed but dynamically adjusted via an AC switch assembly. This AC switch assembly acts as a precise bridge switch, changing the circuit connections between components to enable the subsystem to flexibly perform various preset functions.

[0079] In normal operation mode, the AC switch group connects the first bidirectional controller to the main propulsion motor. At this time, the first bidirectional controller acts as a rectifier and inverter, converting the DC power output from the DC power supply into AC power adapted to the main propulsion motor, thereby driving the main propulsion motor to operate and providing forward power for the ship. At the same time, the AC switch group connects the second bidirectional controller to the AC output module. The second bidirectional controller converts the DC power into AC power required by the ship's AC loads, and then sends it to various AC electrical equipment through the AC output module to ensure the ship's normal power supply needs.

[0080] When the ship is in a regenerative braking state or has excess electrical energy, the AC switch group switches its connection, connecting both the first and second bidirectional controllers to the AC output module. At this time, the AC power supplied by the AC output module is converted to DC power by these two bidirectional controllers and then fed back to the DC power source, effectively charging the DC power source and recovering and utilizing energy.

[0081] If the first bidirectional controller fails, the AC switch assembly will quickly adjust the connection to establish a connection between the second bidirectional controller and the main propulsion motor. At this time, the second bidirectional controller temporarily takes over the function of the first bidirectional controller, converting the DC power supply to AC power to supply the main propulsion motor, ensuring the continuous operation of the main propulsion motor and preventing the ship's power from being interrupted due to the failure of a single controller.

[0082] In the multi-subsystem architecture, the second bidirectional controllers of each ship's electric propulsion subsystem serve as backups for each other. When the second bidirectional controller of one subsystem malfunctions, the second bidirectional controllers of other subsystems can intervene through a preset coordination mechanism to temporarily assume its responsibilities, further improving the redundancy and reliability of the entire electric propulsion system and ensuring the stable operation of the ship under complex operating conditions.

[0083] In this embodiment, the AC switch group includes:

[0084] The first AC switch is connected at one end to the first bidirectional controller and at the other end to the main propulsion motor;

[0085] The second AC switch is connected at one end to the second bidirectional controller and at the other end to the main propulsion motor;

[0086] The third AC switch is connected at one end to the second bidirectional controller and at the other end to the AC output module;

[0087] The fourth AC switch is connected at one end to the first bidirectional controller and at the other end to the second bidirectional controller.

[0088] Specifically, the AC switch group is the core control unit in the ship's electric propulsion subsystem, enabling equipment connection reconfiguration, function mode switching, and redundant path activation. It consists of a first AC switch, a second AC switch, a third AC switch, and a fourth AC switch. The first AC switch is directly connected at one end to the AC output of the first bidirectional controller and at the other end to the power input of the main propulsion motor, forming the main path from the first bidirectional controller to the main propulsion motor. The second AC switch is connected at one end to the AC output of the second bidirectional controller and at the other end to the power input of the main propulsion motor, forming a redundant path from the second bidirectional controller to the main propulsion motor. The third AC switch is connected at one end to the AC output of the second bidirectional controller and at the other end to the input of the isolation transformer of the AC output module, forming the main path from the second bidirectional controller to the AC output module (in-ship load / shore power interaction). The fourth AC switch is connected at both ends to the AC outputs of the first and second bidirectional controllers, respectively, to enable electrical parallel or collaborative operation of the two controllers. The AC switch group enables flexible switching of the ship's electric propulsion system in multiple scenarios such as normal operation, fault redundancy, charging and discharging, and emergency coordination through the independent control and coordinated linkage of four switches. This design allows the ship's electric propulsion system to break through the limitation of a single fixed function and become a core node of a smart energy network that can be dynamically reconfigured according to operating conditions.

[0089] In this embodiment, the AC output module includes:

[0090] Isolation transformer, fifth AC switch and AC busbar;

[0091] One end of the isolation transformer is connected to the third AC switch, and the other end is connected to the AC busbar;

[0092] One end of the fifth AC switch is connected to the AC bus. The fifth AC switch is used to connect the AC bus of the shore power supply / shore power equipment / adjacent ship electric propulsion subsystem.

[0093] The AC busbar is electrically connected to the ship's AC load.

[0094] Specifically, the isolation transformer uses electromagnetic isolation to cut off the direct electrical connection between the ship's internal systems and external power sources (shore power / other vessels), preventing high-voltage shore power from entering the ship's low-voltage systems or transmitting shipboard faults to shore-based equipment. It also suppresses harmonic propagation, ensuring the stability of the power grids on both sides. The AC output module, through the isolation transformer ensuring safety, the coordinated allocation of AC busbars, and the design of the fifth AC switch expanding the interaction boundaries, enables the ship's electric propulsion system to stably supply the ship's AC loads while flexibly realizing shore power charging and discharging, ship-shore mutual power supply, and cross-system coordination. Furthermore, through electrical isolation and switch protection mechanisms, it provides safe and reliable technical support for complex power interaction scenarios, serving as a key link in the upgrade of ships from independent power units to energy interconnection nodes.

[0095] In this embodiment, each ship electric propulsion subsystem further includes:

[0096] The DC bus connects the DC power supply to the first bidirectional controller and the second bidirectional controller.

[0097] Specifically, one end of the DC bus is directly connected to the DC power supply, and the other end is connected to the DC input terminals of the first and second bidirectional controllers via branch lines, forming a star connection topology of DC power supply → DC bus → dual controllers. The DC bus typically uses high-current-carrying-capacity copper busbars or cables, equipped with voltage / current sensors, fuse protection devices, and filtering components. It can carry the high-power DC power required for ship propulsion (such as hundreds to thousands of amperes) and monitor the bus status in real time, suppressing DC-side harmonic interference. The DC power output from the DC power supply is shunted by the DC bus and simultaneously supplies power to the first and second bidirectional controllers, avoiding the redundant design of traditional one-to-one wiring (such as the DC power supply being connected to two controllers separately), reducing cable loss and space occupation. When the dual controllers need to work together (such as emergency high-power propulsion or fast charging), the DC bus provides the same DC input to the first and second bidirectional controllers, ensuring that the voltage reference of the two devices is consistent and avoiding coordination conflicts caused by input voltage differences. For example, in the dual-controller parallel charging mode, the DC bus synchronously delivers the rectified DC power from the shore power to both controllers, which then aggregates the power to the DC power supply, improving charging efficiency. Structurally, the DC bus simplifies the connection between the DC power supply and the dual controllers, reducing system complexity; performance-wise, it ensures the stability and anti-interference capability of power transmission, improving equipment operating efficiency; and functionally, it provides crucial support for dual-controller collaboration, multi-scenario switching, and future expansion. Together with the DC-AC coordination of the AC switchgear, it constructs a flexible, efficient, and reliable energy network for the ship's electric propulsion system.

[0098] In this embodiment, the DC power supply includes:

[0099] Multiple battery packs.

[0100] Specifically, the combination of multiple battery packs significantly increases the total capacity of the DC power supply, meeting the energy needs of ships during long-term voyages or high-power propulsion, avoiding range anxiety caused by insufficient capacity of a single battery pack, and achieving redundancy, fault tolerance, and fault isolation.

[0101] In this embodiment, each ship electric propulsion subsystem further includes:

[0102] Multiple first DC switches, each corresponding to a battery pack, have one end connected to the DC bus and the other end connected to the corresponding battery pack.

[0103] Specifically, the first DC switch, through its one-to-one independent control design, enables the battery pack to flexibly switch on and off, isolate faults, and charge and discharge in a coordinated manner. This ensures that a single fault does not affect the overall system, achieves balanced use of the battery pack and energy optimization, and provides a physical safety barrier for system operation and maintenance.

[0104] In this embodiment, it also includes:

[0105] The second DC switch is located between the DC buses of adjacent ship electric propulsion subsystems.

[0106] Specifically, the second DC switch is located between the DC buses of adjacent ship electric propulsion subsystems. Through the second DC switch, the power of each subsystem can be complemented and superimposed, thereby improving the energy utilization efficiency and endurance of the entire ship. It also provides an emergency energy channel for a faulty subsystem, eliminating the risk of loss of power due to a single system failure, and further enhancing the overall reliability and scalability of the ship's electric propulsion system.

[0107] In this embodiment, when the ship is sailing normally, the control strategy of the ship's electric propulsion subsystem is as follows:

[0108] S1. Determine whether the SOC of the DC power supply is greater than the set threshold. If not, shut down the main propulsion motor and the ship's AC load, and disconnect all switches. If yes, compare the SOC of each battery pack, close the first DC switch corresponding to the battery pack with the highest SOC, and open the first DC switch corresponding to the other battery packs. Then execute S2.

[0109] S2. Determine if the second bidirectional controller is faulty. If not, control the third AC switch to close and control the third AC switch of other ship electric propulsion subsystems to open and the fifth AC switch to close, so that the second bidirectional controller supplies power to the ship's AC load. Execute S4. If yes, control the third AC switch to open and execute S3.

[0110] S3. Determine if there is a fault in the second bidirectional controller of the adjacent ship's electric propulsion subsystem. If not, control the second bidirectional controller to close, and control the third AC switch and the fifth AC switch of the adjacent ship's electric propulsion subsystem to close, and the second bidirectional controller to open, so that the second bidirectional controller of the adjacent ship's electric propulsion subsystem supplies power to the ship's AC load. Execute S4. If yes, control the third AC switch of the adjacent ship's electric propulsion subsystem to open, and execute S4.

[0111] S4. Determine if there is a fault in the first bidirectional controller. If not, proceed to S5; if yes, proceed to S6.

[0112] S5. Control the first AC switch to close and the second AC switch to open, and control the main propulsion motor to run by the first bidirectional controller, then return to S1;

[0113] S6. Determine if there is a fault in the second bidirectional controller. If yes, control the main propulsion motor to shut down and return to S1; otherwise, execute S7.

[0114] S7. Determine whether the second bidirectional controller controls the main propulsion motor to run. If yes, execute S9; if no, control the second bidirectional controller to stop supplying power to the ship's AC load, then control the third AC switch to open and the second AC switch to close, and execute S8.

[0115] S8. Determine if there is a fault in the second bidirectional controller of the adjacent ship's electric propulsion subsystem. If yes, control the third AC switch of the adjacent ship's electric propulsion subsystem to open and execute S9. If no, control the third AC switch and the fifth AC switch of the adjacent ship's electric propulsion subsystem to close, control the second bidirectional controller of the adjacent ship's electric propulsion subsystem to open, and supply power to the ship's AC load by the second bidirectional controller of the adjacent ship's electric propulsion subsystem and execute S9.

[0116] S9. The main propulsion motor is controlled by the second bidirectional controller to execute S10;

[0117] S10. Determine if the first bidirectional controller is faulty. If so, return to S5; otherwise, control the second bidirectional controller to shut down and execute S5.

[0118] Specifically, this control strategy takes DC power supply (SOC) as a prerequisite and the status (fault / normal) of the bidirectional controller as the judgment node. Through the on / off combinations of switch groups, it achieves coordinated control of the main propulsion motor drive and the ship's AC load power supply. In the event of equipment failure, redundant paths within or across subsystems are activated, ultimately forming a control closed loop of "status detection → decision execution → cyclic feedback". By prioritizing SOC scheduling and using single-battery-pack power supply, it reduces balancing losses between battery packs and improves energy utilization efficiency. The second bidirectional controller within the subsystem can simultaneously provide redundant AC load power supply and main propulsion drive; the second bidirectional controllers of adjacent subsystems can provide cross-system support, forming double insurance. Full-process status detection (SOC, controller fault) automatically executes switching logic in the event of a fault, and autonomously switches back to primary mode after recovery, reducing reliance on crew operation. Mechanisms such as forced hibernation when battery is low and rapid power-off in case of fault prevent safety risks such as battery over-discharge and equipment overload from the source. This control strategy, based on power priority scheduling, equipment status detection, dynamic switching of switch groups, and redundancy path activation, enables the ship's electric propulsion subsystem to efficiently utilize energy during normal operation and seamlessly switch during equipment failures. This comprehensively improves the system's reliability, economy, and safety, perfectly meeting the core requirements of new energy ships for low consumption, stability, and intelligence.

[0119] In this embodiment, when the ship docks to charge the battery pack, the control strategy of the ship's electric propulsion subsystem is as follows:

[0120] The fifth AC switch is connected to the shore power supply / adjacent ship electric propulsion subsystem, and the first AC switch is opened, the second AC switch is opened, the third AC switch is closed, the fourth AC switch is closed, the fifth AC switch is closed, and the first DC switch corresponding to the lowest SOC battery pack is closed. At this time, the first bidirectional controller and the second bidirectional controller convert the AC power supplied by the shore power supply to the AC output module into DC power to provide the corresponding battery pack for charging.

[0121] Specifically, the ship's electric propulsion subsystem connects the fifth AC switch to the shore power supply and controls the first AC switch to open, the second AC switch to open, the third AC switch to close, the fourth AC switch to close, the fifth AC switch to close, and the first DC switch corresponding to the lowest SOC battery pack to close. At this time, the first and second bidirectional controllers convert the AC power supplied by the shore power supply to the AC output module into DC power to charge the corresponding battery pack. After the adjacent ship's electric propulsion subsystem closes the fifth AC switch, its AC bus is connected to the AC bus of this ship's electric propulsion subsystem, and it is also charged through the above control strategy. This control strategy aims to maximize charging efficiency and prioritize charging low-charge batteries. By combining the states of the AC switch group and the first DC switch, a charging path of "shore power → AC output module → dual controller rectification → low-charge battery pack" is constructed, while disconnecting from the propulsion system to avoid energy waste.

[0122] In this embodiment, when the ship is docked and discharges power to shore-based electrical equipment or the power grid, the control strategy of the ship's electric propulsion subsystem is as follows:

[0123] The fifth AC switch is connected to shore-based electrical equipment or the power grid / adjacent ship electric propulsion subsystem, and controls the first AC switch to open, the second AC switch to open, the third AC switch to close, the fourth AC switch to close, the fifth AC switch to close, and the first DC switch to close. At this time, the first bidirectional controller and the second bidirectional controller convert the DC power output from the DC power supply into AC power and send it to the AC output module, thereby providing it to the shore-based electrical equipment or the power grid.

[0124] Specifically, after the ship's electric propulsion subsystem is connected to shore-based electrical equipment or the power grid, it controls the opening and closing of the first AC switch, the second AC switch, the third AC switch, the fourth AC switch, the fifth AC switch, and the first DC switch. At this time, the first and second bidirectional controllers convert the DC power output from the DC power supply into AC power and supply it to the AC output module, thereby providing power to the shore-based electrical equipment or the power grid. After the adjacent ship's electric propulsion subsystem closes the fifth AC switch, its AC bus is connected to the AC bus of this ship's electric propulsion subsystem, and it also supplies power to the shore-based electrical equipment or the power grid through the above control strategy. This discharge control strategy, through system equipment coordination and precise control of switch states, converts the energy stored in the ship's DC power supply (battery pack) into AC power usable on shore, realizing the efficient and safe output of ship energy storage to shore. It breaks through the traditional positioning of ships as simple electrical users, making them mobile energy storage stations, participating in shore-based energy networks, exploring the value of redundant battery storage, and expanding new energy service scenarios for the shipping industry.

[0125] Example 2

[0126] like Figure 2 As shown, this embodiment provides a ship electric propulsion system, including:

[0127] Ship electric propulsion subsystem A and ship electric propulsion subsystem B;

[0128] Ship electric propulsion subsystem A includes:

[0129] A DC power supply consisting of battery packs BT1 and BT2, a first bidirectional controller I1, a second bidirectional controller I2, a main propulsion motor M1, an AC output module consisting of an isolation transformer T1 and a fifth AC switch S7, an AC switch group consisting of a first AC switch S1, a second AC switch S2, a third AC switch S3, and a fourth AC switch S4, a first DC switch S8, a first DC switch S9, and the first DC switch S8 and the first DC switch S9 are connected to the first bidirectional controller I1 and the second bidirectional controller I2 via a DC bus;

[0130] Ship electric propulsion subsystem B includes:

[0131] A DC power supply consisting of battery packs BT3 and BT4, a first bidirectional controller I3, a second bidirectional controller I4, a main propulsion motor M2, an AC output module consisting of an isolation transformer T3 and a fifth AC switch S6, an AC switch group consisting of a first AC switch S12, a second AC switch S13, a third AC switch S14, and a fourth AC switch S15, a first DC switch S10, a first DC switch S11, and the first DC switch S10 and the first DC switch S11 are connected to the first bidirectional controller I3 and the second bidirectional controller I4 via a DC bus;

[0132] A second DC switch S5 is provided between the DC buses of the ship's electric propulsion subsystem A and the ship's electric propulsion subsystem B;

[0133] like Figure 3 As shown, during normal ship operation, in the ship's electric propulsion subsystem A, if the SOC of the battery pack is greater than a set threshold, and the charge of battery pack BT1 is greater than or equal to the charge of battery pack BT2, the first DC switch S8 closes and the first DC switch S9 opens; otherwise, the first DC switch S9 closes and the first DC switch S8 opens. Then, it checks if the second bidirectional controller I2 is faulty. If not, it opens the third AC switch S14 and disables the second bidirectional controller I4, sending signals to close the third AC switch S3 and the fifth AC switch S6. When closed, the second bidirectional controller I2 is enabled. If the second bidirectional controller I2 is faulty, it sends a signal to open the third AC switch S3. After opening, it checks if the second bidirectional controller I4 is faulty. If not, it sends a signal to open the third AC switch S3, disabling the second bidirectional controller I2, and closes the third AC switch S14, the fifth AC switch S6, and enables the second bidirectional controller I4 to operate in inverter mode. If the second bidirectional controller I4 is faulty, it opens the third AC switch S14. Next, it checks if the first bidirectional controller I1 is faulty. If not, the first AC switch S1 is closed and the second AC switch S2 is opened. Then, the first bidirectional controller I1 is enabled to control the main propulsion motor M1, and then it returns to SOC detection. If the first bidirectional controller I1 detects a fault, it checks if the second bidirectional controller I2 is faulty. If not, it checks if the second bidirectional controller I2 is operating in propulsion mode. If not, it disables the second bidirectional controller I2, then controls the third AC switch S3 to open and the second AC switch S2 to close. Then, it checks if the second bidirectional controller I4 is faulty. If not, it closes the third AC switch S14 and the fifth AC switch S6, then enables the second bidirectional controller I4 to operate in inverter mode. Then, it enables the second bidirectional controller I2 to control the main propulsion motor M1. This achieves the function of redundant control of the main propulsion motor M1 by the second bidirectional controller I2. When the fault of the first bidirectional controller I1 is cleared, the program can automatically determine and disable the operation of the second bidirectional controller I2. After disconnecting the second AC switch S2, it jumps back to the first bidirectional controller I1 to control the main propulsion motor M1 to run. Then, it restores the operation of the daytime inverter of the second bidirectional controller I2. The second bidirectional controller I4 is used as a backup redundancy.

[0134] When the ship docks to charge its batteries, the fifth AC switch S7, the third AC switch S3, and the fourth AC switch S4 are closed, while the first AC switch S1, the second AC switch S2, and the second DC switch S5 are opened. Based on the charge levels of battery packs BT1 and BT2, the battery pack with the lower charge is charged first. For example, if battery pack BT1 has a lower charge, the first DC switch S8 is closed. The 380VAC shore power supply is transmitted through isolation transformer T2, the fifth AC switch S7, the isolation transformer T1, the third AC switch S3, and the fourth AC switch S4 to power the first bidirectional controller I1 and the second bidirectional controller I2, respectively. The first and second bidirectional controllers I1 and I2 are bidirectional controllers capable of both inversion and rectification. After rectification, they rapidly charge the battery packs. When S6 is closed, the ship's electric propulsion subsystem B functions similarly to ship's electric propulsion subsystem A. The first and second bidirectional controllers I3 and I4 rectify the power to rapidly charge battery packs BT3 and BT4 of ship's electric propulsion subsystem B.

[0135] When the ship is moored at shore and needs to discharge power to shore-based electrical appliances or the power grid, the fourth AC switch S4, the third AC switch S3, the fifth AC switch S7, and the fifth AC switch S6 are closed, while the first AC switch S1, the second AC switch S2, and the second DC switch S5 are opened. Priority is given to using the battery pack with the highest capacity. For example, if battery pack BT1 has a high capacity, the first DC switch S8 is closed, and battery pack BT1 supplies power to the first bidirectional controller I1 and the second bidirectional controller I2. The first bidirectional controller I1 and the second bidirectional controller I2 invert the AC power and, through the isolation transformer T1, supply power to the ship's internal and shore-based electrical appliances or feed it back to the power grid. The first bidirectional controller I3 and the second bidirectional controller I4 of the ship's electric propulsion subsystem B operate similarly to those of the ship's electric propulsion subsystem A, jointly providing high-power energy to internal and external electrical appliances or the power grid.

[0136] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A marine electric propulsion system, characterized in that, include: At least two ship electric propulsion subsystems, each of which includes: DC power supply, first bidirectional controller, second bidirectional controller, main propulsion motor, AC output module and AC switch assembly; The first bidirectional controller, the second bidirectional controller, the main propulsion motor, and the AC output module are electrically connected via an AC switch group. The DC power supply is electrically connected to the first bidirectional controller and the second bidirectional controller; The following functions can be achieved by changing the connection relationship between the first bidirectional controller, the second bidirectional controller, the main propulsion motor, and the AC output module using an AC switch group: The first bidirectional controller converts the DC power output from the DC power supply into AC power to supply the main propulsion motor and control its operation. The second bidirectional controller converts the DC power output from the DC power supply into AC power and sends it to the AC output module, thereby providing AC power to the ship's loads. The first bidirectional controller and the second bidirectional controller convert the AC power supplied by the AC output module into DC power to supply the DC power supply for charging. When the first bidirectional controller fails, the second bidirectional controller converts the DC power output from the DC power supply into AC power to supply the main propulsion motor in order to control the operation of the main propulsion motor. The second bidirectional controllers of each ship's electric propulsion subsystem serve as backups for each other.

2. The ship electric propulsion system according to claim 1, characterized in that, The AC switch group includes: The first AC switch is connected at one end to the first bidirectional controller and at the other end to the main propulsion motor; The second AC switch is connected at one end to the second bidirectional controller and at the other end to the main propulsion motor; The third AC switch is connected at one end to the second bidirectional controller and at the other end to the AC output module; The fourth AC switch is connected at one end to the first bidirectional controller and at the other end to the second bidirectional controller.

3. A marine electric propulsion system according to claim 2, characterized in that, The AC output module includes: Isolation transformer, fifth AC switch and AC busbar; One end of the isolation transformer is connected to the third AC switch, and the other end is connected to the AC busbar; One end of the fifth AC switch is connected to the AC bus. The fifth AC switch is used to connect the AC bus of the shore power supply / shore power equipment / adjacent ship electric propulsion subsystem. The AC busbar is electrically connected to the ship's AC load.

4. A marine electric propulsion system according to claim 3, characterized in that, Each of the aforementioned ship electric propulsion subsystems also includes: The DC bus connects the DC power supply to the first bidirectional controller and the second bidirectional controller.

5. A ship electric propulsion system according to claim 4, characterized in that, The DC power supply includes: Multiple battery packs.

6. A marine electric propulsion system according to claim 5, characterized in that, Each of the aforementioned ship electric propulsion subsystems also includes: Multiple first DC switches, each corresponding to a battery pack, have one end connected to the DC bus and the other end connected to the corresponding battery pack.

7. A marine electric propulsion system according to claim 6, characterized in that, Also includes: The second DC switch is located between the DC buses of adjacent ship electric propulsion subsystems.

8. A ship electric propulsion system according to claim 7, characterized in that, When the ship is sailing normally, the control strategy of the ship's electric propulsion subsystem is as follows: S1. Determine whether the SOC of the DC power supply is greater than the set threshold. If not, shut down the main propulsion motor and the ship's AC load, and disconnect all switches. If yes, compare the SOC of each battery pack, close the first DC switch corresponding to the battery pack with the highest SOC, and open the first DC switch corresponding to the other battery packs. Then execute S2. S2. Determine if the second bidirectional controller is faulty. If not, control the third AC switch to close and control the third AC switch of other ship electric propulsion subsystems to open and the fifth AC switch to close, so that the second bidirectional controller supplies power to the ship's AC load. Execute S4. If yes, control the third AC switch to open and execute S3. S3. Determine if there is a fault in the second bidirectional controller of the adjacent ship's electric propulsion subsystem. If not, control the second bidirectional controller to close, and control the third AC switch and the fifth AC switch of the adjacent ship's electric propulsion subsystem to close, and the second bidirectional controller to open, so that the second bidirectional controller of the adjacent ship's electric propulsion subsystem supplies power to the ship's AC load. Execute S4. If yes, control the third AC switch of the adjacent ship's electric propulsion subsystem to open, and execute S4. S4. Determine if there is a fault in the first bidirectional controller. If not, proceed to S5; if yes, proceed to S6. S5. Control the first AC switch to close and the second AC switch to open, and control the main propulsion motor to run by the first bidirectional controller, then return to S1; S6. Determine if there is a fault in the second bidirectional controller. If yes, control the main propulsion motor to shut down and return to S1; otherwise, execute S7. S7. Determine whether the second bidirectional controller controls the main propulsion motor to run. If yes, execute S9; if no, control the second bidirectional controller to stop supplying power to the ship's AC load, then control the third AC switch to open and the second AC switch to close, and execute S8. S8. Determine if there is a fault in the second bidirectional controller of the adjacent ship's electric propulsion subsystem. If yes, control the third AC switch of the adjacent ship's electric propulsion subsystem to open and execute S9. If no, control the third AC switch and the fifth AC switch of the adjacent ship's electric propulsion subsystem to close, control the second bidirectional controller of the adjacent ship's electric propulsion subsystem to open, and supply power to the ship's AC load by the second bidirectional controller of the adjacent ship's electric propulsion subsystem and execute S9. S9. The main propulsion motor is controlled by the second bidirectional controller to execute S10; S10. Determine if the first bidirectional controller is faulty. If so, return to S5; otherwise, control the second bidirectional controller to shut down and execute S5.

9. A marine electric propulsion system according to claim 8, characterized in that, When the ship docks to charge its battery packs, the control strategy for the ship's electric propulsion subsystem is as follows: The fifth AC switch is connected to the shore power supply / adjacent ship electric propulsion subsystem, and the first AC switch is opened, the second AC switch is opened, the third AC switch is closed, the fourth AC switch is closed, the fifth AC switch is closed, and the first DC switch corresponding to the lowest SOC battery pack is closed. At this time, the first bidirectional controller and the second bidirectional controller convert the AC power supplied by the shore power supply to the AC output module into DC power to provide the corresponding battery pack for charging.

10. A marine electric propulsion system according to claim 1, characterized in that, When the ship is docked and discharges into the shore-based electrical equipment or power grid, the control strategy of the ship's electric propulsion subsystem is as follows: The fifth AC switch is connected to shore-based electrical equipment or the power grid / adjacent ship electric propulsion subsystem, and controls the first AC switch to open, the second AC switch to open, the third AC switch to close, the fourth AC switch to close, the fifth AC switch to close, and the first DC switch to close. At this time, the first bidirectional controller and the second bidirectional controller convert the DC power output from the DC power supply into AC power and send it to the AC output module, thereby providing it to the shore-based electrical equipment or the power grid.

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