A marine bidirectional energy dynamic closed-loop circuit based on an AFE device

Abstract

The utility model provides a kind of marine bidirectional energy dynamic closed loop circuit based on AFE device, including shaft generator, frequency conversion load motor, AFE frequency converter, distribution board, DC bus, bidirectional DC / DC converter, energy storage battery, PLC controller;Shaft generator and frequency conversion load motor are connected in parallel in the AC side of AFE frequency converter by AC bus, and both share the energy conversion and control function of AFE frequency converter;DC bus is connected energy storage battery by bidirectional DC / DC converter, and bidirectional DC / DC converter can flexibly control the charge and discharge of energy storage battery, realize the bidirectional energy dynamic closed loop of circuit.The utility model solves the problem of energy waste, control inflexibility, debugging and maintenance inconvenience of existing circuit system, simultaneously realizes the efficient recovery and utilization of energy, improves the adaptability of circuit system under complex working condition, improves operation and maintenance efficiency, reduces ship operating cost.

Description

Technical Field

[0001] This utility model relates to the field of marine power systems, specifically, a marine bidirectional energy dynamic closed-loop circuit based on an AFE device. Background Technology

[0002] Currently, shaft-driven generators and variable frequency load devices play a crucial role in marine propulsion systems. Shaft-driven generators utilize the surplus power of the main engine to generate electricity, achieving energy conservation; while variable frequency load devices can flexibly adjust power output according to the application load scenario, making these devices more sensitive and stable to operate, and improving the load control performance.

[0003] However, most existing ship shaft generator and variable frequency load systems use independent frequency converter configurations. Even in solutions that share frequency converters, there are still many shortcomings. First, energy flow is mostly unidirectional. The large amount of regenerative energy generated during braking of the variable frequency load device cannot be effectively recovered and utilized. It can only be converted into heat energy and dissipated through the braking resistor, resulting in serious energy waste. Second, when dealing with the complex and ever-changing operating conditions of ships, the control logic is not flexible enough and it is difficult to quickly and accurately meet the energy requirements of shaft generators and variable frequency loads under different operating states. This not only affects the ship's maneuverability but also reduces energy utilization efficiency.

[0004] None of the published patents have shared an AFE inverter with the shaft generator and the variable frequency load, nor have they constructed a complete bidirectional energy dynamic closed-loop management system. Therefore, designing an efficient, convenient, and stable bidirectional energy dynamic closed-loop circuit is particularly important. Utility Model Content

[0005] To address the shortcomings of existing technologies, the purpose of this invention is to provide a marine bidirectional energy dynamic closed-loop circuit based on an AFE device. This circuit system is a shared active front-end (AFE) frequency converter for both the ship's shaft-driven generator and the variable frequency load device, achieving bidirectional energy dynamic closed-loop operation. It can solve the problems of energy waste, inflexible control, and inconvenient debugging and maintenance in existing circuit systems, achieving efficient energy recovery and utilization, improving the system's adaptability under complex operating conditions, increasing operation and maintenance efficiency, and reducing ship operating costs.

[0006] According to the present invention, a marine bidirectional energy dynamic closed-loop circuit based on an AFE device includes a shaft-driven generator, a variable frequency load motor, an AFE frequency converter, a power distribution board, a DC bus, a bidirectional DC / DC converter, an energy storage battery, a PLC controller, and a CAN bus.

[0007] The variable frequency load motor is at least one;

[0008] The shaft-driven generator, variable frequency load motor, AFE frequency converter, and switchboard are connected in parallel.

[0009] The DC bus is connected to the energy storage battery through a bidirectional DC / DC converter. The bidirectional DC / DC converter can flexibly control the charging and discharging of the energy storage battery, realizing bidirectional energy flow between the DC bus and the energy storage battery.

[0010] The shaft-driven generator and the variable frequency load motor are connected in parallel to the AC side of the AFE frequency converter via the AC bus; this allows the regenerative energy generated by the variable frequency load motor to be fed back to the DC bus through the AFE frequency converter, and the two can share the energy conversion and control functions of the AFE frequency converter.

[0011] The PLC controller communicates with the AFE frequency converter via a CAN bus and can control the energy feedback relay of the AFE frequency converter.

[0012] Furthermore, it also includes an onshore commissioning center, which is connected to the onshore commissioning center through the 5G IoT module built into the PLC controller to realize remote wireless commissioning function.

[0013] Furthermore, it also includes ship loads, which are connected to the switchboard.

[0014] Furthermore, the AFE inverter adopts a three-level topology and has the ability to support bidirectional energy flow of ±150% of rated power, ensuring energy transmission between the shaft-driven generator and the variable frequency load motor.

[0015] Furthermore, the energy storage battery adopts an energy storage battery pack with a capacity of ≥100kWh and a response time of <10ms.

[0016] Furthermore, during normal navigation, the shaft-driven generator converts the surplus power of the main engine into electrical energy, which is then rectified by the AFE frequency converter to prioritize the operation of the variable frequency load motor. If the power required by the variable frequency load motor is less than the output power of the shaft-driven generator, the remaining energy is inverted by the AFE frequency converter and transmitted to the ship's power grid to power other electrical equipment.

[0017] Furthermore, when the variable frequency load motor generates a large amount of regenerative energy, the AFE inverter switches to inverter mode to feed the regenerative energy back to the DC bus.

[0018] Furthermore, the PLC controller can monitor the DC bus voltage and the SOC of the energy storage battery in real time. When the DC bus voltage rises and the SOC of the energy storage battery is lower than the set value, the PLC controller triggers the energy storage battery to quickly absorb regenerated energy. When the SOC of the energy storage battery reaches or exceeds the set value, the PLC controller controls the AFE inverter to invert the remaining regenerated energy and send it to the distribution board for use in other electrical equipment, thereby realizing energy recovery and reuse.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. System stability: Through the redundant architecture of the AFE frequency converter's own control and the PLC controller control, the energy feedback and output of the AFE frequency converter can be more dynamically and stably controlled in both directions.

[0021] 2. Significant energy saving: By sharing the AFE circuit design between the shaft-driven generator and the variable frequency load motor, approximately 40% of equipment investment can be saved, the space occupied in the engine compartment can be reduced, and the braking energy of the variable frequency load can be efficiently recovered and utilized.

[0022] 3. Reliable performance: The redundant design of the PLC controller and the energy storage battery smooth out power fluctuations, reduce equipment impact, extend the service life of shaft generators, frequency conversion load devices and other electrical equipment, improve the reliability of the ship's power system, and reduce maintenance costs and risks.

[0023] 4. Convenient Debugging: The remote wireless debugging function allows maintenance personnel to configure parameters and monitor the system in real time via a mobile app or a computer at the shore debugging center, eliminating the need for on-site operation. This reduces on-site maintenance workload, shortens fault diagnosis and repair time, and ensures normal vessel operation. Attached Figure Description

[0024] Other features, objects, and advantages of this invention will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0025] Figure 1 This is a schematic diagram of a marine bidirectional energy dynamic closed-loop circuit structure based on an AFE device according to this utility model;

[0026] Figure 2 This is a schematic diagram of the energy flow during normal navigation of this utility model;

[0027] Figure 3 This is a schematic diagram of energy flow during variable frequency load braking according to this utility model.

[0028] The diagram shows: 1-shaft generator, 2-variable frequency load motor, 3-AFE frequency converter, 4-distribution board, 5-DC bus, 6-bidirectional DC / DC converter, 7-energy storage battery, 8-PLC controller, 9-CAN bus, 10-shore commissioning center, 11-5G IoT module. Detailed Implementation

[0029] The present invention will now be described in detail with reference to specific embodiments. These embodiments will help those skilled in the art to further understand the present invention, but do not limit the present invention in any way. It should be noted that those skilled in the art can make several changes and improvements without departing from the concept of the present invention. These all fall within the protection scope of the present invention.

[0030] like Figure 1 As shown in the figure, this embodiment of a marine bidirectional energy dynamic closed-loop circuit based on an AFE device includes a shaft-driven generator 1, a variable frequency load motor 2, an AFE inverter 3, a power distribution board 4, an energy storage battery 7, a PLC controller 8, and a shore-based commissioning center 10. The shaft-driven generator 1, the variable frequency load motor 2, the AFE inverter 3, and the power distribution board 4 are connected in parallel. The DC bus 5 is connected to the energy storage battery 7 via a bidirectional DC / DC converter 6. The PLC controller 8 communicates with the AFE inverter 3 via a CAN bus 9 and is connected to the shore-based commissioning center 10 via a 5G IoT module 11 built into the PLC controller 8 to realize remote wireless commissioning function.

[0031] Specifically, the shaft-driven generator 1 and the variable frequency load motor 2 are connected in parallel to the AC side of the AFE inverter 3 via an AC bus, allowing them to share the energy conversion and control functions of the AFE inverter 3. The DC bus 5 is connected to the energy storage battery 7 via a bidirectional DC / DC converter 6. The bidirectional DC / DC converter 6 can flexibly control the charging and discharging of the energy storage battery 7 according to the system's energy requirements, realizing bidirectional energy flow between the DC bus 5 and the energy storage battery 7. Specifically, the variable frequency load device can be a bow thruster, stern thruster, main thruster, crane, anchor winch, or other devices.

[0032] AFE inverter 3: Utilizing a three-level topology, it supports bidirectional energy flow of ±150% of rated power, ensuring flexible energy transfer between the shaft-driven generator 1 and the variable-frequency load motor 2 under complex operating conditions. Specifically, in this embodiment, a DANFOSS NX series AFE inverter with a power rating of 500kW, a switching frequency of 16kHz, and a total harmonic distortion (THD) of less than 3% is selected. Its advanced three-level topology and control algorithm meet the requirements of bidirectional energy flow and stable voltage control of the DC bus 5 in this embodiment. Furthermore, sharing the AFE inverter 3 saves approximately 40% of equipment investment and reduces engine room space requirements; it overcomes the high cost and large space requirements caused by separately configuring AFE inverters 3 for the shaft-driven generator 1 and the variable-frequency load motor 2 in existing technologies.

[0033] PLC Controller 8: Currently, the energy flow of AFE frequency converters in use on the market is controlled by the converter itself. When the AFE's built-in control hardware and software fails, the AFE will be unable to open or close the relay controlling the energy flow due to the fault. At this time, energy cannot be regulated and controlled, and excessive energy will damage the equipment and system. The PLC controller 8, which communicates with the AFE frequency converter 3, will automatically start running its software, collecting the DC bus voltage of the AFE frequency converter 3 in real time: if the DC voltage is higher than the set value, it will forcibly open the energy feedback relay of the AFE frequency converter 3; if the DC voltage is lower than the set value, it will forcibly close the energy feedback relay of the AFE frequency converter 3. Through the redundant architecture of the AFE frequency converter 3's self-control and the PLC controller 8's control, the stable and reliable operation of the AFE frequency converter 3's energy feedback and output bidirectional dynamic closed loop can be ensured.

[0034] In this embodiment, a Siemens S7-1500 series PLC controller is used, equipped with a high-performance central processing unit and a variety of expansion modules. It integrates an AI / AO module for accurate acquisition of analog signals; and has a built-in 5G IoT module 11 for stable and high-speed communication with the onshore commissioning center 10, enabling intelligent system control and remote commissioning.

[0035] Energy storage battery 7: An energy storage battery pack with a capacity ≥100kWh and a response time <10ms is selected. During the braking instant of the variable frequency load motor 2, it can quickly absorb regenerative energy spikes to prevent overvoltage on the DC bus 5; when the system needs it, it can also quickly release energy to assist the shaft-driven generator 1 in supplying power to the variable frequency load motor 2 and the distribution board 4, thus smoothing power fluctuations. Specifically, in this embodiment, a super battery pack manufactured by CATL is used, with a rated voltage of DC700V, a capacity of 100kWh, and a cycle life exceeding 10... 6 The response time is less than 10ms. This meets the requirements for high capacity, high reliability, and fast response, effectively mitigating power fluctuations.

[0036] Working principle:

[0037] Normal navigation mode: During normal navigation, the shaft generator 1 converts the surplus power of the main engine into electrical energy, which is then rectified by the AFE inverter 3 to prioritize the operation of the variable frequency load motor 2. If the power required by the variable frequency load motor 2 is less than the output power of the shaft generator 1, the remaining energy is inverted by the AFE inverter 3 and transmitted to the ship's electrical grid to power other electrical equipment.

[0038] During normal navigation, the energy flow diagram is as follows: Figure 2As shown, the energy of the shaft-driven generator 1 flows to the variable frequency load motor 2 and the power grid after rectification by the AFE. Specifically, during this process, the PLC controller 8 monitors the load changes of the variable frequency load motor 2 in real time and dynamically adjusts the modulation strategy of the AFE inverter 3 to ensure that the DC bus 5 voltage is stable at 680V±2%, thus ensuring the stability of the circuit.

[0039] Variable frequency load braking mode: When the variable frequency load device brakes frequently, the variable frequency load motor 2 generates a large amount of regenerative energy. At this time, the AFE inverter 3 switches to inverter mode and feeds the regenerative energy back to the DC bus 5. The PLC controller 8 monitors the voltage of the DC bus 5 and the SOC of the energy storage battery 7 in real time. When the voltage of the DC bus 5 rises and the SOC of the energy storage battery 7 is lower than 80%, the energy storage battery 7 is triggered to quickly absorb regenerative energy. When the SOC of the energy storage battery 7 reaches 80% or above, the AFE inverter 3 is controlled to invert the remaining regenerative energy and send it to the switchboard 4 for powering other ship loads, thus realizing energy recovery and reuse.

[0040] The energy flow diagram during variable frequency load braking is shown below. Figure 3 As shown, the energy of the variable frequency load motor 2 is inverted by the AFE inverter 3, and part of it is absorbed by the energy storage battery 7 and part of it is transmitted to the distribution board 4. For example, when a container ship enters or leaves the port, the variable frequency load device (such as the side thruster) is frequently used, and a large amount of braking energy is generated. At this time, this braking energy will be effectively recovered and converted into electrical energy to power other electrical equipment or absorbed by the energy storage battery 7.

[0041] After applying this embodiment, the energy recovery rate of variable frequency load braking is ≥70%, achieving efficient recycling and reuse. This saves approximately 30 tons of fuel annually and reduces CO2 emissions by approximately 94 tons, significantly reducing energy waste, lowering the ship's dependence on external energy sources, and substantially improving energy conservation, emission reduction, and operational economic benefits. Taking a medium-sized ship as an example, it can save approximately 150,000 yuan in fuel costs annually, improving energy utilization efficiency and economic benefits; it also overcomes the problem of unidirectional energy flow and severe energy waste during variable frequency load braking.

[0042] In the description of this application, it should be understood that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0043] The specific embodiments of this utility model have been described above. It should be understood that this utility model is not limited to the specific embodiments described above, and those skilled in the art can make various changes or modifications within the scope of the claims, which do not affect the substantive content of this utility model. Unless otherwise specified, the embodiments and features described in this application can be arbitrarily combined with each other.

Claims

1. An AFE device based bidirectional energy dynamic closed loop circuit for marine applications, characterized by, include: Shaft-driven generator (1), variable frequency load motor (2), AFE frequency converter (3), switchboard (4), DC bus (5), bidirectional DC / DC converter (6), energy storage battery (7); The variable frequency load motor (2) is at least one; The shaft-driven generator (1), the variable frequency load motor (2), the AFE frequency converter (3), and the distribution board (4) are connected in parallel; The DC bus (5) is connected to the energy storage battery (7) through a bidirectional DC / DC converter (6). The bidirectional DC / DC converter (6) can control the charging and discharging of the energy storage battery (7) to realize bidirectional energy flow between the DC bus (5) and the energy storage battery (7). The shaft-driven generator (1) and the variable frequency load motor (2) are connected in parallel to the AC side of the AFE inverter (3) via the AC bus; so that the regenerative energy generated by the variable frequency load motor (2) is fed back to the DC bus (5) through the AFE inverter (3).

2. A bidirectional energy dynamic closed loop circuit for marine applications based on AFE device according to claim 1, characterized in that, It also includes: PLC controller (8), CAN bus (9); The PLC controller (8) communicates with the AFE frequency converter (3) via the CAN bus (9); The PLC controller (8) can control the energy feedback relay of the AFE frequency converter (3).

3. A bidirectional energy dynamic closed loop circuit for marine applications based on AFE devices according to claim 2, characterized in that, It also includes an onshore commissioning center (10); The PLC controller (8) is connected to the onshore debugging center (10) via its built-in 5G IoT module (11) to enable remote wireless debugging.

4. The AFE device based marine bidirectional energy dynamic closed loop circuit according to claim 1, wherein, The AFE inverter (3) adopts a three-level topology and has the ability to support bidirectional energy flow of ±150% of rated power, ensuring the energy transmission between the shaft-driven generator (1) and the variable frequency load motor (2).

5. The AFE device based marine bidirectional energy dynamic closed loop circuit according to claim 1, wherein, The energy storage battery (7) adopts an energy storage battery pack with a capacity of ≥100kWh and a response time of <10ms.

6. A bidirectional energy dynamic closed loop circuit for marine applications based on AFE device according to claim 1, characterized in that, It also includes ship loads; the ship loads are connected to the switchboard (4).

7. A bidirectional energy dynamic closed loop circuit for marine applications based on AFE device according to claim 1, characterized in that, When the ship is sailing normally, the shaft generator (1) converts the surplus power of the main engine into electrical energy. After rectification by the AFE inverter (3), it prioritizes the operation of the variable frequency load motor (2). If the power required by the variable frequency load motor (2) is less than the output power of the shaft generator (1), the remaining energy is inverted by the AFE inverter (3) and transmitted to the ship's power grid to supply power to other electrical equipment.

8. A bidirectional energy dynamic closed loop circuit for marine applications based on AFE device according to claim 1, characterized in that, When the variable frequency load motor (2) generates a large amount of regenerative energy, the AFE inverter (3) switches to inverter mode and feeds the regenerative energy back to the DC bus (5).

9. A bidirectional energy dynamic closed loop circuit for marine applications based on AFE device according to claim 2, characterized in that, The PLC controller (8) can monitor the DC bus (5) voltage and the SOC of the energy storage battery (7) in real time. When the DC bus (5) voltage rises and the SOC of the energy storage battery (7) is lower than the set value, the PLC controller (8) triggers the energy storage battery (7) to quickly absorb regenerated energy. When the SOC of the energy storage battery (7) reaches or exceeds the set value, the PLC controller (8) controls the AFE inverter (3) to invert the remaining regenerated energy and send it to the distribution board (4) for use in other electrical equipment, thereby realizing energy recovery and reuse.

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