A multi-brand lithium battery single-inverter system interface device

Abstract

A multi-brand lithium battery single-inverter system interface device, comprising: a housing as an assembly, an installation connection part and a heat dissipation structure are arranged inside the housing; at least two CANbus input ports are arranged on the outside of the housing, are RJ45 interfaces, and are configured to be connected to corresponding battery arrays; a CANbus output port is arranged on the outside of the housing, is an RJ45 interface, and is configured to be connected to the BMS input of an inverter; a microcontroller is arranged in the inside of the housing and is configured to read battery status data from each CANbus input port; a data fusion module is arranged in the inside of the housing and is configured to merge the battery status data into a unified data set; and a protocol conversion module is arranged in the inside of the housing and is configured to convert the unified data set into a communication format compatible with the inverter.

Description

Technical Field

[0001] This utility model relates to the field of energy storage systems, and in particular to a multi-brand lithium battery single inverter system interface device, which is suitable for photovoltaic and hybrid energy systems. It enables compatible connection between lithium battery packs of different brands or models and a single inverter, solving the limitation of traditional inverters that only support batteries of a single brand. Background Technology

[0002] In existing energy storage systems, communication between the inverter and the lithium battery relies on the battery management system (BMS), which uses protocols such as CANbus or RS-485 to achieve safe charging and discharging control. Traditional inverters are typically equipped with only one BMS communication port, and the protocol compatibility of this port is fixed, resulting in the system only being compatible with specific brands or models of lithium batteries.

[0003] When users need to expand their energy storage capacity, the differences in BMS protocols between different battery brands (such as data frame format, command set, and communication rate) prevent direct connection to the same inverter. They must replace the batteries with those from the same brand, resulting in equipment waste and increased costs. Furthermore, firmware limitations exacerbate compatibility issues, meaning that even after replacing the batteries, users may face problems such as complex system debugging and long downtime.

[0004] Therefore, there is an urgent need for an interface device that can be compatible with multiple brands of lithium batteries, and to break through protocol barriers through structural improvements to achieve stable communication between mixed brand batteries and a single inverter. Utility Model Content

[0005] A multi-brand lithium battery single inverter system interface device includes:

[0006] As the outer casing of the assembly, it contains mounting connections and a heat dissipation structure.

[0007] At least two CANbus input ports, mounted on the outside of the housing, are RJ45 interfaces and configured to connect to the corresponding battery array;

[0008] A CANbus output port, mounted externally in the enclosure, is an RJ45 interface configured to connect to the inverter's BMS input;

[0009] The microcontroller, located inside the housing, is configured to read battery status data from each CANbus input port;

[0010] The data fusion module, located inside the casing, is configured to merge the battery status data into a unified dataset;

[0011] The protocol conversion module, located inside the casing, is configured to convert the unified dataset into a communication format compatible with the inverter;

[0012] The at least two CANbus input ports are electrically connected to a microcontroller inside the housing, the microcontroller is electrically connected to a data fusion module, the data fusion module is electrically connected to a protocol conversion module, and the protocol conversion module is electrically connected to a CANbus output port.

[0013] Furthermore, the battery status data includes charging status, voltage, current, fault / alarm status, and temperature.

[0014] Furthermore, the data fusion module calculates a weighted average SOC based on the capacity ratio of the connected battery array.

[0015] Furthermore, the protocol conversion module includes a protocol mapping table, which maps CANbus data frames or proprietary command sets of batteries from different brands to the format required for inverter BMS input through a lookup table.

[0016] Furthermore, it also includes a human-computer interaction component, which includes a display screen and two touch buttons. The display screen is configured to display different battery array protocols, and the buttons are configured to adjust each of the battery array protocols.

[0017] Furthermore, the operation logic of the button is as follows: long press to enter the protocol selection mode and the protocol name of the corresponding battery array flashes; short press to scroll to select compatible protocols; and automatically save the configuration after timeout.

[0018] Furthermore, it also includes a data logger interface, configured to connect to the inverter's data logger, which communicates with the microcontroller through this interface to record and synchronize operating parameters.

[0019] Furthermore, the mounting connection of the housing is a flange structure, which is fixed to the area below the inverter data logger by M4 screws; the heat dissipation structure is a ventilation slot opened at the bottom of the housing.

[0020] Furthermore, the CANbus input port, output port, and data logger interface are all equipped with locking connectors, and the CANbus input port includes a switchable RS-485 transceiver.

[0021] Furthermore, the device obtains power from the inverter's data logger port via the CANbus output port. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the device of this utility model.

[0023] Figure 2 This is a schematic diagram of the data logger interface in this utility model.

[0024] Figure 3 This is one of the schematic diagrams showing the connection between the present invention and the battery.

[0025] Figure 4 This is the second schematic diagram showing the connection between this utility model and the battery.

[0026] Figure 5 This is the third schematic diagram of the connection between this utility model and the battery.

[0027] Figure 6 This is a schematic diagram of the connection interface between the present invention and the battery.

[0028] Figure 7 This is a schematic diagram of the working process of the device of this utility model.

[0029] Figure 8 This is the working logic diagram of the device of this utility model. Detailed Implementation

[0030] The physical structure and component layout of this device are as follows:

[0031] like Figure 1-2 As shown, the housing 1 is designed to fit the inverter's installation space, with an overall shape that accommodates the internal mainboard and interfaces. The surface has flanges (connecting parts) for fixing, which connect to the pre-drilled holes below the inverter's data logger area using two M4 screws. Three RJ45 interfaces (input port 4 and output port 5) are horizontally arranged on one side of housing 1. All interfaces have locking clips that engage with the plug to prevent loosening. A display screen is embedded in the center of the front of housing 1, with two clear buttons (the first and second buttons) arranged side-by-side below, covered by a transparent protective window. A strip-shaped ventilation channel (ventilation slot) with a width of 2mm and a spacing of 5mm is provided at the bottom of housing 1 to ensure airflow.

[0032] The internal motherboard is made of FR-4 material and is fixed inside the housing 1 by four plastic mounting posts. The motherboard size is adapted to the inner cavity of housing 1. An STM32F103CBT6 microcontroller with a main frequency of 72MHz is soldered to the center of the motherboard. Its peripheral components include: a communication circuit for input port 4, connecting to a CANbus transceiver TJA1050, supporting CAN 2.0A / B, and switchable via a DIP switch to connect to either the TJA1050 or an RS-485 transceiver MAX3485; a circuit for output port 5, integrating a TVS diode and an isolated CAN transceiver to ensure electrical isolation from the inverter; a data fusion module, consisting of an LM358 operational amplifier forming an adder circuit for current / voltage summation; a protocol conversion module, containing an EEPROM (AT24C02) storing a protocol mapping table and a hardware timer (STM32 built-in TIM2) to trigger data conversion at regular intervals; and a power supply circuit, converting the 5V voltage provided by the inverter to 3.3V via an LDO chip to power the microcontroller and peripheral components.

[0033] like Figure 3-6 As shown, the RJ45 pin definitions for input port 4 and output port 5 are unified: pin 4 (CAN_H), pin 5 (CAN_L), pin 3 (+5V), pin 6 (GND), and the remaining pins are reserved. When port 4 switches to RS-485 mode, pin 1 (A line) and pin 2 (B line) are activated, replacing the CAN signal. Figure 6 This is a schematic diagram of the interface and pins.

[0034] The device's workflow is based on the coordinated operation of the hardware architecture, and the specific steps are as follows:

[0035] Remove the original data logger from the inverter, fix the device to the bottom of the inverter using a flange, connect output port 5 to the BMS input port of the inverter via an RJ45 cable, connect input port 4 to the BMS output terminals of battery 1 and battery 2 respectively, and reconnect the data logger to the device's through interface.

[0036] The inverter supplies power to the device through output port 5. The 5V voltage is converted to 3.3V via an LDO. The microcontroller starts up and performs a self-test: checking the connection status of each port, judging by pin levels, testing the display screen to light up, displaying the initialization interface, and checking the continuity of the button circuit. After the self-test passes, the display shows the default protocol, namely BAT1:SUNSYNKA / BAT2:SUNSYNKA.

[0037] Battery 1's BMS sends CANbus data frames through port 4, such as sending one frame of SOC data every 100ms, ID=0x200, with data bits 0-1 representing the SOC value. This data is converted to TTL level signals by the TJA1050 transceiver and transmitted to the microcontroller's CAN peripheral. Battery 2's BMS sends RS-485 data through port 4, such as sending one frame of voltage data every 200ms. This data is converted by the MAX3485 transceiver and transmitted to the microcontroller's USART peripheral.

[0038] The microcontroller receives data in real time through interrupt service routines, parses the content according to the preset protocol library, extracts the SOC value from the frame with ID=0x200, and temporarily stores it in the internal RAM buffer. The circular buffer design prevents data overflow.

[0039] Figure 7 The complete process of configuring the battery array protocol is shown in detail, and the operation logic and device response for each step are as follows:

[0040] Step 1: Initialize the display

[0041] After the device passes the power-on self-test, the display screen automatically lights up and shows the default protocol configuration interface, in the format BAT1:SUNSYNKA / BAT2:SUNSYNKA. At this time, the protocol names of the two battery arrays are always lit, indicating that the current mode is protocol viewing and no configuration operation is triggered.

[0042] Step 2: Press and hold the button to enter the protocol selection mode.

[0043] To configure the BAT1 protocol, press and hold the first button for 2 seconds: the microcontroller detects that the pin has been continuously low for 2 seconds, triggers a configuration interrupt, and controls the display screen to start flashing the protocol name SUNSYNKA corresponding to BAT1, while the BAT2 protocol name remains constantly lit, indicating that the BAT1 protocol selection mode has been entered; to configure the BAT2 protocol, press and hold the second button for 2 seconds, and similarly, the BAT2 protocol name will flash while the BAT1 protocol name remains constantly lit.

[0044] Step 3: Short press the button to scroll and select compatible protocols

[0045] In protocol selection mode (corresponding battery protocol name flashes), short press the corresponding button (press the first button for BAT1 configuration, press the second button for BAT2 configuration). Each short press will switch the protocol name in the order of the preset list. After each switch, the flashing state will continue, making it easy for users to confirm the current selection. The protocol list is pre-stored in the microcontroller's Flash and only includes brand protocols compatible with the device to avoid invalid selections.

[0046] Step 4: Automatically save configuration after timeout

[0047] After switching to the target protocol, if there is no button operation within 5 seconds, the microcontroller determines that the user has confirmed the configuration and automatically writes the current protocol information to permanent storage. After storage is completed, the protocol name corresponding to the battery on the display screen stops flashing and returns to a steady light. The interface returns to the BAT1:SUNSYNKA / BAT2:SUNSYNKA viewing mode, and the configuration takes effect without the need for additional manual saving.

[0048] Figure 8 This is a functional logic block diagram of the device, clearly showing the data flow and collaborative operation relationships between each module. The specific logic is as follows:

[0049] The power module provides core power, and the inverter supplies power to the device through the CANbus output port. The 5V voltage is first input to the power module in the block diagram. After being converted into a stable 3.3V voltage by the chip, it powers the "Battery Management System 1 / 2 Communication Circuit, Microcontroller, Data Fusion Module, Protocol Conversion Module, Human-Machine Interaction Components, and Data Logger", ensuring that all modules start up together after being powered on.

[0050] Battery Management System 1 / 2 Signal Access and Conversion: The BMS signal of Battery 1, i.e. the CANbus protocol, is accessed through the Battery Management System 1 port, converted into a TTL level signal by the CANbus transceiver TJA1050, and transmitted to the microcontroller's CAN peripheral.

[0051] The BMS signal of battery 2 (switchable CANbus / RS-485 protocol) is connected through the battery management system 2 port. If it is CANbus protocol, it is converted by TJA1050; if it is RS-485 protocol, it is converted by MAX3485 transceiver. Finally, it is transmitted to the corresponding peripheral of the microcontroller.

[0052] The input / output interface module monitors the connection status of each port in real time and transmits the connection status signal synchronously to the microcontroller for self-testing and abnormal alarms.

[0053] As the logic core, the microcontroller receives data from each module and performs the following operations:

[0054] The battery status data transmitted by the battery management system 1 / 2 is parsed and temporarily stored in an internal RAM circular buffer to prevent data overflow.

[0055] The buffer data is periodically sent to the data fusion module, and the button operation signals (such as long press and short press) are converted into configuration instructions to control the protocol display and flashing status of the display screen.

[0056] The system receives the unified dataset from the data fusion module, forwards it to the protocol conversion module, and receives the inverter compatibility signal converted by the protocol conversion module. It then sends the signal to the inverter BMS input through the communication interface port between the inverter and the battery management system.

[0057] After receiving two battery data streams from the microcontroller, the data fusion module calculates the total current (battery 1 current + battery 2 current) through a hardware addition circuit, calculates the weighted average SOC based on the battery capacity ratio through a software algorithm, and merges fault states through a logic circuit. If any battery is overvoltaged, it is marked as an overvoltage fault and a unified dataset is generated and fed back to the microcontroller.

[0058] The protocol conversion module calls the protocol mapping table in the EEPROM to convert the unified dataset into the CAN frame format required by the inverter (e.g., ID=0x300, data bits 2-3 store the SOC value). It is triggered by a hardware timer (STM32 built-in TIM2) to synchronize the inverter polling frequency and transmit the converted data to the MCU. The MCU then outputs the data through the communication interface between the inverter and the battery management system.

[0059] The display screen receives control commands from the microcontroller, drives the display screen to show the protocol configuration interface and status, and at the same time feeds back the button operation signals to the microcontroller, realizing a configuration-display-confirmation closed loop;

[0060] The data logger connects to the microcontroller via SPI communication, and collects operating parameters such as communication rate of each port, protocol conversion delay ≤5ms, and battery data update frequency in real time. It packages the data every 30 seconds and synchronizes it to the platform through the data logger interface 3 for remote monitoring.

[0061] The flange connection and power reuse design of the outer casing 1 of this device simplify the installation process from the traditional wiring-fixing-debugging to fixing-plugging, which can be completed by a single person, saving time compared to traditional systems. The linkage structure between the buttons and the display screen allows users to configure the protocol on-site without connecting to a computer or upgrading firmware. All the beneficial effects of this device are directly generated by the above structure. Relying on the hardware structure of independent input ports and switchable transceivers, the physical isolation design of port 4 allows CANbus and RS-485 protocols to operate simultaneously. In actual testing, it supports mixed access of batteries from brands such as Sunsynk, LG, and CATL, solving the protocol conflict problem of traditional single-port devices.

Claims

1. An interface device for a multi-brand lithium battery single inverter system, characterized in that, include: The housing (1) of the assembly has an internal mounting connection and a heat dissipation structure; At least two CANbus input ports (4) are mounted on the outside of the housing (1) and are RJ45 interfaces configured to connect to the corresponding battery array; A CANbus output port (5), mounted on the outside of the housing (1), is an RJ45 interface and is configured to connect to the BMS input of the inverter; The microcontroller, located inside the housing (1), is configured to read battery status data from each CANbus input port (4); The data fusion module is located inside the outer casing (1) and is configured to merge the battery status data into a unified dataset; The protocol conversion module, located inside the housing (1), is configured to convert the unified dataset into a communication format compatible with the inverter; The at least two CANbus input ports (4) are electrically connected to the microcontroller inside the housing (1), the microcontroller is electrically connected to the data fusion module, the data fusion module is electrically connected to the protocol conversion module, and the protocol conversion module is electrically connected to the CANbus output port (5).

2. The apparatus according to claim 1, characterized in that, The battery status data includes charging status, voltage, current, fault / alarm status, and temperature.

3. The apparatus according to claim 1, characterized in that, The data fusion module calculates a weighted average SOC based on the capacity ratio of the connected battery array.

4. The apparatus according to claim 1, characterized in that, The protocol conversion module includes a protocol mapping table, which maps CANbus data frames or proprietary command sets of batteries from different brands to the format required by the inverter battery management system through a lookup table.

5. The apparatus according to claim 1, characterized in that, It also includes a human-computer interaction component, which includes a display screen and two touch buttons (2), the display screen being configured to display different battery array protocols and the buttons being configured to adjust each of the battery array protocols.

6. The apparatus according to claim 5, characterized in that, The operation logic of the button is as follows: long press to enter the protocol selection mode, short press to scroll through and select compatible protocols, and automatically save the configuration after timeout.

7. The apparatus according to claim 1, characterized in that, It also includes a data logger interface (3), configured to connect to the inverter's data logger, which communicates with the microcontroller through the interface to record and synchronize operating parameters.

8. The apparatus according to claim 1, characterized in that, The mounting connection of the outer casing (1) is a flange structure, which is fixed to the area below the inverter data logger by M4 screws; the heat dissipation structure is a ventilation slot opened at the bottom of the outer casing (1).

9. The apparatus according to claim 1, characterized in that, The CANbus input port (4), output port and data logger interface (3) are all equipped with locking connectors, and the CANbus input port (4) can be switched to enable RS-485 transceiver.

10. The apparatus according to claim 1, characterized in that, The device obtains power from the inverter's data logger port via the CANbus output port (5).

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