A charging and discharging control system for large-capacity electric boats

Abstract

The present application discloses a charging and discharging control system for a large-capacity electric boat, the control system comprising: a shore-based charging device for charging the battery pack of the electric boat, a detection device for detecting whether the electric boat is docked with the shore-based charging device, and an energy management system comprising an execution layer and a control layer, wherein the execution layer comprises a plurality of parallel DC / DC bidirectional conversion devices to connect a DC bus and at least one group of parallel battery packs, and a collection unit of the control layer collects battery status information of the battery pack, so that the main controller determines the maximum total discharge current of the plurality of parallel DC / DC bidirectional conversion devices and the discharge current of the battery pack according to the battery status information, and when it is determined that the electric boat is docked with the shore-based charging device, the maximum total charging current of the plurality of parallel DC / DC bidirectional conversion devices and the charging current of the battery pack are determined according to the battery status information. Through the technical solution in the present application, the charging and discharging control strategy of multiple clusters of battery packs in the electric boat is optimized.

Description

Technical Field

[0001] The present application relates to the technical field of electric boats, and in particular to a charging and discharging control system for large-capacity electric boats. Background Art

[0002] With the continuous development of technologies in my country's new energy field, especially the release of the inspection guidelines for solar photovoltaic systems and lithium iron phosphate battery systems by China Classification Society in 2015, the development of new energy ships has entered a stage of rapid development.

[0003] However, due to the large demand for ship power, in order to ensure the normal operation of new energy ships, the battery capacity required for new energy ships is relatively large. For example, the battery capacity of Wuhan's 300-passenger all-electric passenger ship in 2018 reached 2300kWh, and the battery capacity of Yichang Transportation's "Two Dams and One Gorge" cruise ship in 2018 reached 7500kWh. Therefore, multiple clusters of battery packs need to be connected in parallel.

[0004] In the prior art, the battery charge and discharge management control strategy is usually implemented for a single battery pack, without considering the overcharge and over-discharge problems of multiple battery packs, nor the impact of fluctuations in the rear-end load on the charging and discharging system of the electric boat caused by the special navigation environment of the electric boat, such as water flow velocity, wind direction and wind speed.

[0005] At the same time, since electric boats use multiple battery clusters connected in parallel, in order to reduce the production and manufacturing costs of electric boats, multiple battery clusters are usually required to share a DC / DC charge and discharge control device. Therefore, when one of the multiple battery clusters under a DC / DC charge and discharge control device fails, the remaining battery clusters will have overcurrent, causing the entire DC / DC charge and discharge control device to stop working, affecting the normal operation of the electric boat. Summary of the invention

[0006] The purpose of this application is to optimize the charge and discharge control strategy of multiple battery clusters in an electric boat, improve the safety and reliability of the electric boat's navigation, and facilitate energy management.

[0007] The technical solution of the present application is: to provide a charging and discharging control system for a large-capacity electric boat, wherein a DC bus and multiple battery packs are arranged on the electric boat, wherein the multiple battery packs are connected in parallel to the DC bus, and the battery packs are used to power the electric boat, and the control system comprises: a shore-based charging device, a detection device and an energy management system; the detection device is used to detect whether the electric boat is docked with the shore-based charging device, and the shore-based charging device is used to charge the battery pack, and the energy system comprises: an execution layer and a control layer; the execution layer comprises a plurality of parallel DC / DC bidirectional conversion devices, wherein one end of the DC / DC bidirectional conversion device is connected to the DC bus, and the other end of the DC / DC bidirectional conversion device is connected to at least one group of parallel battery packs, and the DC / DC bidirectional conversion device is used to adjust the charging current and discharging current of the battery pack Current; the control layer includes a collection unit and a main controller, the collection unit is electrically connected to the input end of the main controller, the collection unit is used to collect battery status information of the battery pack, the main controller is electrically connected to the control end of the DC / DC bidirectional conversion device, the main controller is used to determine the maximum total discharge current of multiple parallel DC / DC bidirectional conversion devices according to the battery status information, and determine the discharge current of the battery pack connected to the DC / DC bidirectional conversion device according to the maximum total discharge current, the main controller is also used to determine the maximum total charging current of multiple parallel DC / DC bidirectional conversion devices according to the battery status information when it is determined that the electric boat is docked with the shore-based charging device, and determine the charging current of the battery pack connected to the DC / DC bidirectional conversion device according to the maximum total charging current.

[0008] In any of the above technical solutions, further, the execution layer includes an inverter power supply and a propulsion inverter, one end of the inverter power supply is connected to the DC bus, the other end of the inverter power supply is connected to the first power unit of the electric ship, one end of the propulsion inverter is connected to the DC bus, and the other end of the propulsion inverter is connected to the second power unit of the electric ship, the battery status information includes the residual charge, and the main controller is used to determine the maximum total discharge current of multiple parallel DC / DC bidirectional conversion devices according to the battery status information, specifically including: when it is determined that the residual charge is greater than the charge threshold, the maximum total discharge current is determined according to the rated power of the inverter power supply and the propulsion inverter; when it is determined that the residual charge is less than or equal to the charge threshold, the working mode of the inverter power supply is set to the unloading mode, and the working mode of the propulsion inverter is set to the power limiting mode, and the maximum total discharge current is determined according to the first power of the inverter power supply in the unloading mode and the second power of the propulsion inverter in the power limiting mode.

[0009] In any of the above technical solutions, further, the battery status information also includes the battery pack ampere-hour, and the main controller determines the maximum total discharge current of multiple parallel DC / DC bidirectional conversion devices according to the battery status information, specifically including: step 11, when it is determined that the battery pack ampere-hour is greater than the first threshold, the first threshold is determined as the maximum total discharge current of the DC / DC bidirectional conversion device, wherein the first threshold is the smaller value of the discharge current calculation value and the rated discharge current of the DC / DC bidirectional conversion device, and the discharge current calculation value is determined by the power of the inverter power supply and the propulsion inverter; step 12, when it is determined that the battery pack ampere-hour is less than or equal to the first threshold and greater than the second threshold, the maximum total discharge current of the DC / DC bidirectional conversion device is determined according to the product of the second threshold and the number of battery packs mounted on the DC / DC bidirectional conversion device, wherein the second threshold is the ratio of the first threshold to the total number of battery packs; step 13, when it is determined that the battery pack ampere-hour is less than or equal to the second threshold, the maximum total discharge current of the DC / DC bidirectional conversion device is determined according to the product of the battery pack ampere-hour and the number of battery packs mounted on the DC / DC bidirectional conversion device.

[0010] In any of the above technical solutions, further, the battery status information also includes the battery pack ampere-hour, and the main controller determines the maximum total charging current of multiple parallel DC / DC bidirectional conversion devices based on the battery status information, specifically including: Step 21, when it is determined that the battery pack ampere-hour is greater than the third threshold, the third threshold is determined as the maximum total charging current of the DC / DC bidirectional conversion device, wherein the third threshold is the smaller value of the charging current calculated value and the rated charging current of the DC / DC bidirectional conversion device, and the charging current calculated value is determined by the rated power of the shore-based charging device and the bus voltage of the DC bus.

[0011] In any of the above technical solutions, further, the main controller determines the maximum total charging current of multiple parallel DC / DC bidirectional conversion devices based on the battery status information, and specifically also includes: step 22, when it is determined that the battery pack ampere-hour is less than or equal to the third threshold and greater than the fourth threshold, the maximum total charging current of the DC / DC bidirectional conversion device is determined according to the product of the fourth threshold and the number of battery packs mounted on the DC / DC bidirectional conversion device, wherein the fourth threshold is the ratio of the third threshold to the total number of battery packs; step 23, when it is determined that the battery pack ampere-hour is less than the fourth threshold, the maximum total charging current of the DC / DC bidirectional conversion device is determined according to the product of the battery pack ampere-hour and the number of battery packs mounted on the DC / DC bidirectional conversion device.

[0012] In any of the above technical solutions, further, the battery status information also includes branch fault information, and the main controller determines the maximum total discharge current of multiple parallel DC / DC bidirectional conversion devices according to the battery status information, specifically including: counting the number of faulty batteries in the battery pack according to the branch fault information; determining the expected discharge current according to the number of faulty batteries, the total number of battery packs, and the allowable discharge current of the battery pack; when it is determined that the expected discharge current is greater than the rated discharge current of the DC / DC bidirectional conversion device, recording the rated discharge current as the maximum total discharge current of the DC / DC bidirectional conversion device under the fault state, otherwise, recording the expected discharge current as the maximum total discharge current of the DC / DC bidirectional conversion device under the fault state.

[0013] In any of the above technical solutions, further, the control system also includes a monitoring layer, and the monitoring layer includes: a first display and a second display; the first display is arranged in the engine room of the electric boat; and the second display is arranged in the control room of the electric boat.

[0014] In any of the above technical solutions, further, the control layer also includes: a slave controller; the slave controller is electrically connected between the main controller and the DC / DC bidirectional conversion device, and real-time network communication is adopted between the slave controller and the main controller.

[0015] The beneficial effects of this application are:

[0016] The technical solution in the present application optimizes the charge and discharge control strategy for multiple cluster battery packs in large-capacity electric ships, and separately controls the charge and discharge state of the battery packs in different working modes, the charge and discharge current direction of the battery system, and the charge and discharge current size of the battery system, thereby improving the safety and reliability of the electric ship's navigation discharge and docking charging, and facilitating energy management.

[0017] In a preferred implementation of the present application, in order to further optimize the charge and discharge control strategy, battery status information is introduced to determine the maximum total discharge current of multiple parallel DC / DC bidirectional conversion devices to avoid overcharging and over-discharging of lithium batteries during the charging and discharging process of the battery pack. At the same time, when multiple clusters of battery packs are connected in parallel, it can also avoid the situation where one cluster of battery packs is discharged while another cluster of battery packs is still fully charged.

[0018] In another preferred implementation of the present application, branch fault information is set in the battery status information so that the maximum total discharge current of multiple parallel DC / DC bidirectional conversion devices under the branch fault state can be determined based on the branch fault information, thereby improving the reliability of the charge and discharge control strategy. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The advantages of the above and / or additional aspects of the present application will become apparent and easily understood in the description of the embodiments in conjunction with the following drawings, in which:

[0020] Figure 1 is a schematic diagram of a charging and discharging control system for a large-capacity electric ship according to an embodiment of the present application;

[0021] Figure 2 is a schematic diagram of an energy management system according to an embodiment of the present application. DETAILED DESCRIPTION

[0022] In order to more clearly understand the above-mentioned purposes, features and advantages of the present application, the present application is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. It should be noted that the embodiments of the present application and the features in the embodiments can be combined with each other without conflict.

[0023] In the following description, many specific details are elaborated to facilitate a full understanding of the present application. However, the present application may also be implemented in other ways different from those described herein. Therefore, the protection scope of the present application is not limited to the specific embodiments disclosed below.

[0024] Embodiment 1:

[0025] like Figure 1 As shown, this embodiment provides a charging and discharging control system for a large-capacity electric boat. A DC bus and multiple battery packs are provided on the electric boat. The multiple battery packs are connected in parallel to the DC bus. The battery packs are used to power the electric boat. The control system includes: a shore-based charging device, a detection device, and an energy management system.

[0026] The shore-based charging device is used to charge the battery pack, and the detection device is used to detect whether the electric boat is docked with the shore-based charging device. When the electric boat is docked with the shore-based charging device, the detection device sends a docking success instruction to the energy management system so that the energy management system can charge multiple clusters of battery packs according to the control logic and algorithm.

[0027] In this embodiment, the energy system includes: an execution layer and a control layer; when the large-capacity electric ship operates in different normal working modes and fault modes, the control layer adopts a corresponding control strategy algorithm to control the operation of the equipment in the execution layer, thereby realizing the control of the large-capacity electric ship in different normal working modes and fault modes.

[0028] In the energy system, the execution layer includes a plurality of parallel DC / DC bidirectional conversion devices, one end of the DC / DC bidirectional conversion device is connected to a DC bus, the other end of the DC / DC bidirectional conversion device is connected to at least one parallel battery group, and the DC / DC bidirectional conversion device is used to adjust the charging current and discharging current of the battery group;

[0029] Specifically, Figure 2 As shown, the execution layer includes a battery pack, a battery management system, a DC / DC bidirectional conversion device, an inverter, a propulsion inverter, etc. Among them, one end of the DC / DC bidirectional conversion device is connected to the DC bus, and the other end thereof can be connected to a single battery pack, two battery packs, or three battery packs.

[0030] One end of the inverter power supply is connected to the DC bus, and the other end of the inverter power supply is connected to the first power unit of the electric boat, which may be a lighting lamp, a power socket, etc. One end of the propulsion inverter is connected to the DC bus, and the other end of the propulsion inverter is connected to the second power unit of the electric boat, which may be a motor or other device that provides power to the electric boat.

[0031] In the energy system, the control layer includes a collection unit and a main controller. The collection unit is electrically connected to the input end of the main controller and is used to collect battery status information of the battery pack. The main controller is electrically connected to the control end of the DC / DC bidirectional conversion device.

[0032] It should be noted that this embodiment does not limit the implementation method of the collection unit.

[0033] The main controller is used to determine the maximum total discharge current of multiple parallel DC / DC bidirectional conversion devices according to battery status information, and determine the discharge current of the battery group connected to the DC / DC bidirectional conversion device according to the maximum total discharge current, wherein the battery status information includes the residual charge.

[0034] This embodiment shows a method for determining the maximum total discharge current of multiple parallel DC / DC bidirectional conversion devices according to battery status information, which specifically includes:

[0035] Step A: When it is determined that the remaining charge SOC is greater than the charge threshold, the maximum total discharge current is determined according to the rated power of the inverter power supply and the propulsion inverter; wherein the charge threshold is a set value, and in this embodiment, the charge threshold is set to 20%.

[0036] Step B, when it is determined that the remaining charge SOC is less than or equal to the charge threshold, the working mode of the inverter power supply is set to the unloading mode, and the working mode of the propulsion inverter is set to the power limiting mode, and the maximum total discharge current is determined according to the first power of the inverter power supply in the unloading mode and the second power of the propulsion inverter in the power limiting mode.

[0037] Specifically, the remaining charge SOC in the battery status information is compared with the charge threshold 20%, and the comparison result is as follows:

[0038] (1) If SOC (residual charge) is greater than 20%, the inverter and propulsion inverter can operate at rated power. At this time, in order to ensure that the inverter and propulsion inverter can operate normally, the maximum total discharge current of multiple DC / DC bidirectional converters connected in parallel on the DC bus is determined based on the rated power of the two. The discharge current of the battery group connected to the DC / DC bidirectional converter is determined in combination with the power and number of the rear-end propulsion inverter and inverter.

[0039] If the rated power of the propulsion inverter is P1 and the number is m, and the rated power of the inverter power supply is P2 and the number is n, then the maximum total discharge current Im1 of all DC / DC bidirectional conversion devices connected in parallel on the DC bus should be:

[0040] Im1=1.1×(m×P1+n×P2) / U

[0041] Wherein, Im1 is the maximum total discharge current corresponding to the DC / DC bidirectional conversion device when the residual charge SOC is greater than the charge threshold, and U is the bus voltage of the DC bus, which can be 650V.

[0042] (2) When SOC (residual charge) is ≤ 20%, the load at the rear end of the inverter is unloaded, and the inverter enters an unloading mode, which includes at least a first-level unloading and a second-level unloading.

[0043] At the same time, the inverter is driven to work in the power limiting mode, that is, the working power of the inverter is limited in this mode, such as the power limiting coefficient r1 = 50%. At this time, the maximum total discharge current Im1' of all DC / DC bidirectional conversion devices should be:

[0044] Im1'=1.1×(m×P1×r1+n×P2×r2) / U

[0045] Wherein, Im1' is the maximum total discharge current corresponding to the DC / DC bidirectional conversion device when the residual charge SOC is less than or equal to the charge threshold, r1 is the power limit coefficient, and r2 is the unloading coefficient.

[0046] It should be noted that the value of the unloading coefficient r2 is a set value, and the specific form of the unloading mode is not limited in this embodiment. For example, when SOC (residual charge)>10%, the first-level unloading is performed, otherwise, the second-level unloading is performed, wherein the first-level unloading is defined as unloading high-power non-important loads, such as cabin air conditioners, kitchen electric ovens, etc., wherein the definition of non-important loads is loads that do not affect the safety of ship navigation. Similarly, the definition of second-level unloading is to unload low-power non-important loads, such as domestic sewage pumps, etc.

[0047] Furthermore, the battery status information also includes battery pack ampere-hours.

[0048] The battery pack in this embodiment is composed of a plurality of battery cells, and specific parameters are shown in Table 1.

[0049] Table 1

[0050]

[0051]

[0052] That is to say, in this embodiment, each battery pack is composed of 12 280Ah battery cells connected in series, each battery cluster is composed of 13 battery packs connected in series, and the charge and discharge current of each battery cluster cannot be greater than 280A.

[0053] Embodiment 2:

[0054] In order to solve the control strategy and safety of lithium battery charging and discharging of large-capacity electric boats and the energy management of loads, this embodiment also shows a method for the main controller to determine the maximum total discharge current of multiple parallel DC / DC bidirectional conversion devices according to battery status information, so as to avoid overcharging and over-discharging of lithium batteries during the charging and discharging process of the battery pack, and at the same time, when multiple battery packs are connected in parallel, it can also avoid the situation where one battery pack is discharged while another battery pack is still fully charged. The method specifically includes:

[0055] Step 11, when it is determined that the ampere-hour t of the battery pack is greater than the first threshold Im2, the first threshold Im2 is determined as the maximum total discharge current of the DC / DC bidirectional conversion device, wherein the first threshold Im2 is the smaller value of the discharge current calculated value and the rated discharge current of the DC / DC bidirectional conversion device, and the discharge current calculated value is determined by the power of the inverter power supply and the propulsion inverter;

[0056] Specifically, the power of the inverter power supply and the propulsion inverter can be determined by the magnitude relationship between the residual charge and the charge threshold. Based on the power of the two, the discharge current calculation value Im2' corresponding to the maximum total discharge current of the DC / DC bidirectional conversion device connected in parallel to the DC bus can be calculated. The corresponding calculation formula is:

[0057] Im2'=1.1×(m×P1'+n×P2') / U

[0058] Wherein, Im2' is the calculated value of the discharge current, P1' is the power of the propulsion inverter, m is the number of propulsion inverters, P2' is the power of the inverter power supply, n is the number of inverter power supplies, and U is the bus voltage of the DC bus, which can be 650V. Among them, the value of P1' is the rated power P1 of the propulsion inverter or the second power P1×r1 of the propulsion inverter in the power limiting mode, and the value of P2' is the rated power P2 of the inverter power supply or the first power P2×r2 of the inverter power supply in the unloading mode.

[0059] The rated discharge current of the DC / DC bidirectional converter is set to Im2", and the calculated discharge current value Im2' is compared with the rated discharge current Im2". If Im2">Im2', the first threshold Im2=Im2'; otherwise, the first threshold Im2=Im2".

[0060] Step 12, when it is determined that the ampere-hour t of the battery pack is less than or equal to the first threshold Im2 and greater than the second threshold Im3, the maximum total discharge current of the DC / DC bidirectional conversion device is determined according to the product of the second threshold Im3 and the number of battery packs q1 mounted on the DC / DC bidirectional conversion device, wherein the second threshold is the ratio of the first threshold to the total number of battery packs;

[0061] Specifically, the second threshold Im3 is set to be the ratio of the first threshold Im2 to the total number of battery packs q, that is, Im3=Im2 / q.

[0062] If the first threshold Im2≥t>the second threshold Im3, the maximum total discharge current allowed by each DC / DC bidirectional conversion device is:

[0063] Idc1=Im3×q1

[0064] Wherein, q1 is the number of battery groups mounted on the DC / DC bidirectional conversion device.

[0065] Step 13, when it is determined that the ampere-hour t of the battery pack is less than or equal to the first threshold value and less than or equal to the second threshold value Im3, the maximum total discharge current of the DC / DC bidirectional conversion device is determined according to the product of the ampere-hour t of the battery pack and the number of battery packs mounted under the DC / DC bidirectional conversion device;

[0066] Specifically, if the first threshold Im2≥t and the second threshold Im3≥t, the maximum total discharge current allowed by each DC / DC bidirectional conversion device is:

[0067] Idc2=t×q1.

[0068] Through the above scheme in this embodiment, the safety and reliability of the operation of multiple battery clusters mounted on the same DC / DC bidirectional conversion device can be improved. When two or more battery clusters are mounted on a DC / DC bidirectional conversion device, if one battery cluster fails, the maximum total discharge current of the DC / DC bidirectional conversion device can be adjusted in time to avoid the maximum total discharge current being adjusted in time, resulting in excessive discharge currents of the remaining battery clusters and over-discharge, thereby avoiding the entire DC / DC bidirectional conversion device from stopping working.

[0069] In this embodiment, the main controller is also used to determine the maximum total charging current of multiple parallel DC / DC bidirectional conversion devices based on the battery status information when it is determined that the electric boat is docked with the shore-based charging device, and determine the charging current of the battery pack connected to the DC / DC bidirectional conversion device based on the maximum total charging current, wherein the battery status information also includes the battery pack ampere-hours.

[0070] Furthermore, the method for the main controller to determine the maximum total charging current of a plurality of parallel DC / DC bidirectional conversion devices according to the battery status information specifically includes:

[0071] Step 21, when it is determined that the battery pack ampere-hour t is greater than the third threshold Im4, the third threshold Im4 is determined as the maximum total charging current of the DC / DC bidirectional conversion device, wherein the third threshold Im4 is the smaller value of the charging current calculated value and the rated charging current of the DC / DC bidirectional conversion device, and the charging current calculated value is determined by the rated power of the shore-based charging device and the bus voltage of the DC bus, and the corresponding calculation formula is:

[0072] Im4'=1.1×P / U

[0073] Where, Im4' is the calculated value of the charging current, P is the rated power of the shore-based charging device, and U is the bus voltage of the DC bus, which can be 650V. Set the rated charging current of the DC / DC bidirectional conversion device to Im4", compare the calculated charging current value Im4' with the rated charging current Im4", if Im4">Im4', then Im4=Im4', otherwise, Im4=Im4".

[0074] Step 22, when it is determined that the battery pack ampere-hour t is less than or equal to the third threshold Im4 and greater than the fourth threshold Im5, the maximum total charging current of the DC / DC bidirectional conversion device is determined according to the product of the fourth threshold Im5 and the number of battery packs mounted on the DC / DC bidirectional conversion device, wherein the fourth threshold is the ratio of the third threshold to the total number of battery packs;

[0075] Specifically, the fourth threshold Im5 is set to be the ratio of the third threshold Im4 to the total number of battery packs q, that is, Im5=Im4 / q.

[0076] If Im4≥t>Im5, the maximum total charging current allowed for each DC / DC bidirectional converter is:

[0077] Idc2=Im5×q2

[0078] Wherein, q2 is the number of battery groups mounted under the DC / DC bidirectional conversion device;

[0079] Step 23, when it is determined that the battery pack ampere-hour t is less than the third threshold Im4 and less than the fourth threshold Im5, the maximum total charging current of the DC / DC bidirectional conversion device is determined according to the product of the battery pack ampere-hour t and the number of battery packs mounted on the DC / DC bidirectional conversion device.

[0080] Specifically, if Im4>t and Im5>t, the allowed charging current of each DC / DC bidirectional conversion device is:

[0081] Idc2=t×q2.

[0082] Through the above scheme in this embodiment, the reliability of the charging process of multiple battery clusters mounted on the same DC / DC bidirectional conversion device can be improved. When two or more battery clusters are mounted on a DC / DC bidirectional conversion device, during the charging process, if one battery cluster fails or fails to charge normally, the maximum total charging current of the DC / DC bidirectional conversion device can be adjusted in time to avoid the maximum total charging current being untimely adjusted, resulting in excessive charging currents of the remaining battery clusters and overcharging, thereby preventing the entire DC / DC bidirectional conversion device from stopping working.

[0083] Embodiment three:

[0084] It is understandable to those skilled in the art that as the service life of electric boats continues to increase, the battery packs that serve as the main energy source for the electric boats will age to varying degrees or even be damaged. Due to cost considerations, and on the premise of ensuring the safe navigation of the electric boat, some of the aged battery packs are usually physically isolated and not used. This inevitably causes a significant drop in the electric energy capacity of the electric boat.

[0085] Therefore, based on the above embodiments, in order to more comprehensively optimize the charge and discharge control strategy of multiple battery clusters in electric boats, the battery status information of the charge and discharge control system during the maximum total discharge current of the DC / DC bidirectional conversion device also includes branch fault information.

[0086] When a branch where the battery pack in the electric boat is located fails, the acquisition unit sends branch fault information to the controller in the control layer, and the main controller determines the maximum total discharge current of multiple parallel DC / DC bidirectional conversion devices under the branch fault state according to the branch fault information, specifically including:

[0087] According to the branch fault information, count the number of faulty batteries in the battery pack;

[0088] According to the number of faulty batteries, the total number of battery packs, and the allowable discharge current of the battery pack, the expected discharge current In5 is determined. The corresponding calculation formula is:

[0089] In5=(qm) / q*Ibm

[0090] Where In5 is the expected discharge current, q is the total number of battery packs, m is the number of faulty batteries, and Ibm is the allowable discharge current of the battery pack.

[0091] When it is determined that the expected discharge current In5 is greater than the rated discharge current Im2" of the DC / DC bidirectional conversion device, the rated discharge current Im2" is recorded as the maximum total discharge current Idc3 of the DC / DC bidirectional conversion device in the fault state; otherwise, the expected discharge current In5 is recorded as the maximum total discharge current Idc3 of the DC / DC bidirectional conversion device in the fault state.

[0092] Furthermore, the control system also includes a monitoring layer, which includes: a first display and a second display; the first display is arranged in the engine room of the electric boat, and the first display is a DC power distribution LCD display screen, which is installed on the DC power distribution board in the engine room, and the number of which is determined by the number of branches composed of the battery pack, DC / DC bidirectional conversion device, inverter power supply, propulsion inverter, etc. in the electric boat, and the maximum number is not more than 10. The second display is arranged in the control room or the cab of the electric boat, and the second display is an EMS LCD display screen. The engine room detection system can also be set in the monitoring layer, and the system and equipment status of the large-capacity electric boat can be displayed and monitored through the monitoring layer.

[0093] Furthermore, the control layer also includes: a slave controller; the slave controller is electrically connected between the main controller and the DC / DC bidirectional conversion device, and real-time network communication is adopted between the slave controller and the main controller.

[0094] Specifically, in this embodiment, the main controller is mainly used to collect the status and information of the whole ship system, and to perform control strategy and algorithm control. The slave controller collects the status and information of the whole ship system of the branch, and controls the battery pack, battery management system, DC / DC bidirectional conversion device, inverter power supply, etc. through communication. The main controller and the slave controller use real-time network communication, which can be Profinet or EtherCAT.

[0095] Embodiment 4:

[0096] In order to cooperate with the charge and discharge control system in the above embodiment, this embodiment also shows an implementation method of a battery pack in an electric ship, which is composed of at least two battery packs connected in series, wherein any battery pack is composed of multiple battery cells connected in series, and the output end of the battery pack passes through a series-connected fuse, a protection switch and a power diode in sequence, wherein the positive pole of the power diode is electrically connected to the protection switch, and the negative pole of the power diode is electrically connected to the DC / DC bidirectional conversion device.

[0097] In this embodiment, the protection switch can be a vacuum contactor, a DC switch, or a power electronic switch. The fuse can be a DC fuse that meets selective protection. When the power diode is turned on, the battery pack is connected to the DC bus through a DC / DC bidirectional conversion device to supply power to the DC bus. The power diode should be able to meet the maximum charge and discharge current of the battery pack.

[0098] By setting a power diode and utilizing the unidirectional conduction capability of the power diode, it is possible to prevent the current generated under the braking condition of the motor during the navigation of the electric boat (discharging of the battery pack) from flowing back to the battery pack and causing abnormality of the battery pack.

[0099] Moreover, due to the different charging and discharging characteristics of the battery packs themselves, the battery performance attenuation is inconsistent. When multiple battery packs share a DC / DC bidirectional conversion device, under the action of the reverse current interception capability of the power diode, if there is a difference in the electromotive force between the multiple battery packs, it will cause the battery pack with high electromotive force to discharge to the battery pack with low electromotive force during discharge, causing abnormal operation of the battery pack.

[0100] It should be noted that a switching device is also provided in the battery pack so that when charging is performed using a shore-based charging device, the power diode mentioned above can be cut off from the circuit to ensure that the battery pack can be charged normally.

[0101] By setting the fuse, the safety of the battery pack can be ensured, and the branch fault information can also be used as the above-mentioned battery status information to indicate the failure of the battery pack, so as to adjust the charge and discharge control strategy of the battery pack in time to ensure the safe operation of the electric boat.

[0102] The technical solution of the present application is described in detail above in conjunction with the accompanying drawings. The present application proposes a charging and discharging control system for a large-capacity electric boat, the control system comprising: a shore-based charging device for charging the battery pack of the electric boat, a detection device for detecting whether the electric boat is docked with the shore-based charging device, and an energy management system comprising an execution layer and a control layer, wherein the execution layer comprises a plurality of parallel DC / DC bidirectional conversion devices to connect a DC bus and at least one group of parallel battery packs, and the acquisition unit of the control layer acquires the battery status information of the battery pack, so that the main controller determines the maximum total discharge current of the plurality of parallel DC / DC bidirectional conversion devices and the discharge current of the battery pack according to the battery status information, and when it is determined that the electric boat is docked with the shore-based charging device, the maximum total charging current of the plurality of parallel DC / DC bidirectional conversion devices and the charging current of the battery pack are determined according to the battery status information. Through the technical solution in the present application, the charging and discharging control strategy of multiple clusters of battery packs in electric boats is optimized.

[0103] The steps in this application can be adjusted in order, combined, and deleted according to actual needs.

[0104] The units in the device of the present application can be combined, divided and deleted according to actual needs.

[0105] Although the present application is disclosed in detail with reference to the accompanying drawings, it should be understood that these descriptions are merely exemplary and are not intended to limit the application of the present application. The scope of protection of the present application is defined by the appended claims and may include various modifications, alterations and equivalents made to the invention without departing from the scope and spirit of the present application.

Claims

1. A charging and discharging control system for a large-capacity electric boat, characterized in that: The electric boat is provided with a DC bus and multiple battery packs, the multiple battery packs are connected in parallel to the DC bus, the battery packs are used to power the electric boat, and the control system includes: a shore-based charging device, a detection device and an energy management system; The detection device is used to detect whether the electric boat is docked with the shore-based charging device, and the shore-based charging device is used to charge the battery pack. The energy management system includes: an execution layer and a control layer; The execution layer includes a plurality of parallel DC / DC bidirectional conversion devices, one end of each DC / DC bidirectional conversion device is connected to the DC bus, and the other end of each DC / DC bidirectional conversion device is connected to at least one group of parallel battery packs, and the DC / DC bidirectional conversion device is used to adjust the charging current and discharging current of the battery pack; The control layer includes a collection unit and a main controller, wherein the collection unit is electrically connected to the input end of the main controller and is used to collect battery status information of the battery pack, and the main controller is electrically connected to the control end of the DC / DC bidirectional conversion device. The main controller is used to determine the maximum total discharge current of the plurality of parallel-connected DC / DC bidirectional conversion devices according to the battery status information, and determine the discharge current of the battery pack connected to the DC / DC bidirectional conversion device according to the maximum total discharge current, The main controller is also used to determine the maximum total charging current of the plurality of parallel DC / DC bidirectional conversion devices according to the battery status information when it is determined that the electric boat is docked with the shore-based charging device, and determine the charging current of the battery pack connected to the DC / DC bidirectional conversion device according to the maximum total charging current, The execution layer includes an inverter power supply and a propulsion inverter, one end of the inverter power supply is connected to the DC bus, and the other end of the inverter power supply is connected to the first power unit of the electric ship, one end of the propulsion inverter is connected to the DC bus, and the other end of the propulsion inverter is connected to the second power unit of the electric ship, and the battery status information includes the remaining charge, The main controller is used to determine the maximum total discharge current of the plurality of parallel-connected DC / DC bidirectional conversion devices according to the battery status information, specifically including: When it is determined that the residual charge is greater than a charge threshold, determining the maximum total discharge current according to the rated powers of the inverter power supply and the propulsion inverter; When it is determined that the remaining charge is less than or equal to the charge threshold, the operating mode of the inverter power supply is set to the unloading mode, the operating mode of the propulsion inverter is set to the power limiting mode, and the maximum total discharge current is determined according to the first power of the inverter power supply in the unloading mode and the second power of the propulsion inverter in the power limiting mode. The battery status information also includes battery pack ampere-hours. The main controller determines the maximum total discharge current of the plurality of parallel-connected DC / DC bidirectional conversion devices according to the battery status information, specifically including: Step 11, when it is determined that the ampere-hour of the battery pack is greater than a first threshold, the first threshold is determined as the maximum total discharge current of the DC / DC bidirectional conversion device, wherein the first threshold is the smaller value of the discharge current calculated value and the rated discharge current of the DC / DC bidirectional conversion device, and the discharge current calculated value is determined by the power of the inverter power supply and the propulsion inverter; Step 12, when it is determined that the ampere-hour of the battery pack is less than or equal to the first threshold and greater than a second threshold, the maximum total discharge current of the DC / DC bidirectional conversion device is determined according to the product of the second threshold and the number of battery packs mounted on the DC / DC bidirectional conversion device, wherein the second threshold is the ratio of the first threshold to the total number of battery packs; Step 13, when it is determined that the ampere-hour of the battery pack is less than or equal to the second threshold, the maximum total discharge current of the DC / DC bidirectional conversion device is determined based on the product of the ampere-hour of the battery pack and the number of battery packs mounted on the DC / DC bidirectional conversion device.

2. The charge and discharge control system for a large-capacity electric boat according to claim 1, characterized in that: The battery status information also includes battery pack ampere-hours. The main controller determines the maximum total charging current of the plurality of parallel-connected DC / DC bidirectional conversion devices according to the battery status information, specifically including: Step 21, when it is determined that the battery pack ampere-hour is greater than a third threshold, the third threshold is determined as the maximum total charging current of the DC / DC bidirectional conversion device, Among them, the third threshold is the smaller value of the charging current calculated value and the rated charging current of the DC / DC bidirectional conversion device, and the charging current calculated value is determined by the rated power of the shore-based charging device and the bus voltage of the DC bus.

3. The charge and discharge control system for a large-capacity electric boat according to claim 2, characterized in that: The main controller determines the maximum total charging current of the plurality of parallel-connected DC / DC bidirectional conversion devices according to the battery status information, and specifically includes: Step 22, when it is determined that the ampere-hour of the battery pack is less than or equal to the third threshold and greater than a fourth threshold, the maximum total charging current of the DC / DC bidirectional conversion device is determined according to the product of the fourth threshold and the number of battery packs mounted on the DC / DC bidirectional conversion device, wherein the fourth threshold is the ratio of the third threshold to the total number of battery packs; Step 23, when it is determined that the battery pack ampere-hour is less than the fourth threshold, the maximum total charging current of the DC / DC bidirectional conversion device is determined according to the product of the battery pack ampere-hour and the number of battery packs mounted on the DC / DC bidirectional conversion device.

4. The charge and discharge control system for a large-capacity electric boat according to claim 1, characterized in that: The battery status information also includes branch fault information. The main controller determines the maximum total discharge current of the plurality of parallel DC / DC bidirectional conversion devices according to the battery status information, specifically including: According to the branch fault information, counting the number of faulty batteries in the battery pack; Determine an expected discharge current according to the number of the faulty batteries, the total number of the battery packs, and the allowable discharge current of the battery packs; When it is determined that the expected discharge current is greater than the rated discharge current of the DC / DC bidirectional conversion device, the rated discharge current is recorded as the maximum total discharge current of the DC / DC bidirectional conversion device under a fault state; otherwise, the expected discharge current is recorded as the maximum total discharge current of the DC / DC bidirectional conversion device under a fault state.

5. The charge and discharge control system for a large-capacity electric boat according to claim 1, characterized in that: The control system further comprises a monitoring layer, and the monitoring layer comprises: a first display and a second display; The first display is arranged in the engine room of the electric boat; The second display is arranged in the control room of the electric boat.

6. The charge and discharge control system for a large-capacity electric boat according to claim 1, characterized in that: The control layer also includes: a slave controller; The slave controller is electrically connected between the master controller and the DC / DC bidirectional conversion device, and real-time network communication is adopted between the slave controller and the master controller.

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