Communication circuit, battery management system, battery pack and electric device

Abstract

The invention discloses a communication circuit. An isolation communication unit is electrically connected with a controller; the first switch unit is electrically connected with the controller and the isolation communication unit. The second switch unit is electrically connected with the controller and the isolation communication unit. The first resistor is electrically connected with the isolation communication unit through the first switch unit; the controller sends a first control signal to the first switch unit, the first switch unit is switched off, the controller sends a second control signal to the second switch unit, the second switch unit is switched on, and the communication circuit communicates with the outside in a first communication mode; in response to the second control signal sent by the controller to the first switch unit, the first switch unit is switched on, the controller sends the first control signal to the second switch unit, the second switch unit is switched off, and the communication circuit communicates with the outside in a second communication mode.

Description

Technical Field

[0001] The present application relates to the field of battery management technology, and in particular to a communication circuit, a battery management system, a battery pack, and an electrical device. Background Art

[0002] A battery management system (BMS) manages and controls battery modules. The BMS includes a communication circuit, which enables external communication. For example, the BMS controller communicates with the vehicle's vehicle controller via the communication circuit.

[0003] Different communication methods have emerged to meet the needs of different vehicle manufacturers. This means that a communication circuit that integrates only one communication method on a BMS circuit board cannot be used across different vehicle models. In the prior art, multiple communication circuits supporting multiple communication methods are deployed simultaneously on a single BMS circuit board, with each circuit supporting only one communication method. This results in high costs and poor compatibility. Summary of the Invention

[0004] The embodiments of the present application provide a communication circuit, a battery management system, a battery pack, and an electrical device, which can realize the demand of realizing multiple communication modes based on one communication circuit, thereby reducing the design complexity of the communication circuit, reducing the cost of the BMS circuit board, and improving compatibility.

[0005] In a first aspect, an embodiment of the present application provides a communication circuit, comprising: a controller; an isolated communication unit, electrically connected to the controller; a first switch unit, electrically connecting the controller and the isolated communication unit, respectively; a second switch unit, electrically connecting the controller and the isolated communication unit, respectively; a first power supply and a second power supply, the first power supply being electrically connected to the second switch unit and the isolated communication unit, respectively, and the second power supply being electrically connected to the isolated communication unit; a first resistor, electrically connecting the isolated communication unit through the first switch unit; the communication circuit being configured as follows: in response to the controller sending a first control signal to the first switch unit, the first switch unit is disconnected, the controller sends a second control signal to the second switch unit, the second switch unit is turned on, and the communication circuit communicates with the outside in a first communication mode; in response to the controller sending a second control signal to the first switch unit, the first switch unit is turned on, the controller sends the first control signal to the second switch unit, the second switch unit is disconnected, and the communication circuit communicates with the outside in a second communication mode; wherein the first communication mode is different from the second communication mode.

[0006] According to the communication circuit provided in the embodiment of the present application, when the controller sends a first control signal to the first switch unit and the controller sends a second control signal to the second switch unit, the first switch unit is disconnected and the second switch unit is turned on, and the controller communicates with the outside world in the first communication mode through the isolated communication unit; when the controller sends a second control signal to the first switch unit and the controller sends a first control signal to the second switch unit, the first switch unit is turned on and the second switch unit is disconnected, and the controller communicates with the outside world in the second communication mode through the isolated communication unit. This realizes the need to realize multiple communication modes based on a communication circuit, and is compatible with the application requirements of communication of various vehicle models, thereby reducing costs and improving compatibility. In addition, the communication circuit is powered by the first power supply and the second power supply, so that regardless of the state of the battery pack's positive control switch (the switch is located between the positive electrode B+ of the battery module and the positive output terminal P+ of the battery pack) and the negative control switch (the switch is located between the negative electrode B- of the battery module and the negative output terminal P- of the battery pack), dynamic switching between the first communication mode and the second communication mode can be achieved.

[0007] In one or more embodiments, the controller includes: a first transmit pin electrically connected to the isolated communication unit; a first receive pin electrically connected to the isolated communication unit; a first control pin electrically connected to the isolated communication unit; a second control pin electrically connected to the second switch unit; and a third control pin electrically connected to the first switch unit. The communication circuit is configured to: receive external data in response to the controller sending a first control signal to the isolated communication unit via the first control pin; and transmit data to the outside in response to the controller sending a second control signal to the isolated communication unit via the first control pin.

[0008] In one or more embodiments, the isolated communication unit includes an isolated communication chip, and the isolated communication chip includes: a second transmitting pin, electrically connected to the first transmitting pin; a second receiving pin, electrically connected to the first receiving pin; a first differential pin, electrically connected to the first power supply, and the first differential pin is configured to be electrically connected to the first communication port through the first communication transmission line; a second differential pin, electrically connected to the first power supply through the second switching unit, and the second differential pin is configured to be electrically connected to the second communication port through the second communication transmission line; a first power pin, electrically connected to the first power supply; a second power pin, electrically connected to the second power supply; a drive enable pin, electrically connected to the first control pin; and a receive enable pin, electrically connected to the first control pin.

[0009] In one or more embodiments, the first switching unit includes a first switch, the first switch includes a photo MOSFET, the photo MOSFET includes a first input terminal and a first output terminal; wherein the first pin of the first input terminal is electrically connected to the third control pin, and the second pin of the first input terminal is electrically connected to the first reference ground; the third pin of the first output terminal, the fourth pin of the first output terminal, and the first resistor are connected in series between the first differential pin and the second differential pin.

[0010] In one or more embodiments, the second switch unit includes: a second switch, an isolation element, a second resistor and a third resistor; the first power supply is electrically connected to the first end of the second resistor through the second switch, the second end of the second resistor, the second differential pin, and the first end of the third resistor are electrically connected to the first node, and the second end of the third resistor is electrically connected to the second reference ground; the isolated communication chip includes a first ground pin and a second ground pin, the first ground pin is electrically connected to the second reference ground, and the second ground pin is electrically connected to the first reference ground; the isolation element includes a second input end and a second output end; wherein the first pin of the second input end is electrically connected to the second control pin, and the second pin of the second input end is electrically connected to the first reference ground; the third pin of the second output end is electrically connected to the second reference ground, and the fourth pin of the second output end is electrically connected to the control end of the second switch.

[0011] In one or more embodiments, the second switch unit further includes a fourth resistor and a fifth resistor; the fourth pin of the second output terminal is electrically connected to the control terminal of the second switch via the fourth resistor, and the fifth resistor is electrically connected between the first power supply and the control terminal of the second switch. In one or more embodiments, the resistance value R2 of the second resistor and the resistance value R3 of the third resistor satisfy the following relationship: |V A -V B |≥200mV; V B =(V1×R3) / (R2+R3); where V1 is defined as the voltage of the first power supply, V A and V B Defined as: When the first switch unit is off and the second switch unit is on, the voltage of the first differential pin is V A , the voltage of the second differential pin is V B .

[0012] In one or more embodiments, the isolation element includes a photocoupler or a photo MOSFET, and the second switch includes a PNP transistor or a P-type FET.

[0013] In one or more embodiments, the first communication mode includes one-line communication, and the second communication mode includes RS485 communication.

[0014] In one or more embodiments, the communication circuit also includes at least one of a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor, an eleventh resistor, a twelfth resistor, and a thirteenth resistor; wherein the isolation communication unit includes an isolation communication chip; the second differential pin of the isolation communication chip is configured to be electrically connected to the second communication port through the sixth resistor; the first differential pin is configured to be electrically connected to the first communication port through the seventh resistor; the second sending pin of the isolation communication chip is electrically connected to the first sending pin of the controller through the eighth resistor; the second switch unit is connected to the second control pin of the controller through the ninth resistor; the second receiving pin of the isolation communication chip is electrically connected to the first receiving pin of the controller through the tenth resistor; the drive enable pin and the receive enable pin of the isolation communication chip are electrically connected to the first control pin of the controller through the eleventh resistor; the first switch unit is electrically connected to the third control pin of the controller through the twelfth resistor; and the first differential pin of the isolation communication chip is electrically connected to the first power supply through the thirteenth resistor.

[0015] In one or more embodiments, the communication circuit also includes a fourteenth resistor; wherein the isolated communication unit includes an isolated communication chip; the second receiving pin of the isolated communication chip is electrically connected to the second power supply through the fourteenth resistor; and / or, the communication circuit also includes a fifteenth resistor; the drive enable pin and the receive enable pin of the isolated communication chip are electrically connected to the first reference ground through the fifteenth resistor.

[0016] In one or more embodiments, the communication circuit further includes at least one of a first transient voltage suppression diode, a second transient voltage suppression diode, and a third transient voltage suppression diode; wherein the isolated communication unit includes an isolated communication chip; the first end of the first transient voltage suppression diode is electrically connected to the second differential pin of the isolated communication chip, and the second end of the first transient voltage suppression diode is electrically connected to the second reference ground; the first end of the second transient voltage suppression diode is electrically connected to the second differential pin of the isolated communication chip, and the second end of the second transient voltage suppression diode is electrically connected to the first differential pin; the first end of the third transient voltage suppression diode is electrically connected to the first differential pin of the isolated communication chip, and the second end of the third transient voltage suppression diode is electrically connected to the second reference ground.

[0017] In one or more embodiments, the communication circuit further includes at least one of a first capacitor and a second capacitor; the first end of the first capacitor is electrically connected to the first reference ground, and the second end of the first capacitor is electrically connected to the second power supply; the first end of the second capacitor is electrically connected to the second reference ground, and the second end of the second capacitor is electrically connected to the first power supply.

[0018] In the second aspect, based on the same technical concept, an embodiment of the present application also provides a battery management system, including a first connector and a communication circuit as in the first aspect or any one of the embodiments of the first aspect; the first connector includes a first communication port and a second communication port; the isolated communication unit includes: a first differential pin, electrically connected to the first communication port through a first communication transmission line; a second differential pin, electrically connected to the second communication port through a second communication transmission line.

[0019] In the third aspect, based on the same inventive concept, an embodiment of the present application also provides a battery pack, including a second connector, a battery module, and a battery management system as the embodiment of the second aspect; the second connector is electrically connected to the first connector through a communication harness.

[0020] In a fourth aspect, based on the same inventive concept, an embodiment of the present application further provides an electrical device comprising a battery pack as described in the embodiment of the third aspect.

[0021] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Other features, objects and advantages of the present application will become more apparent by reading the following detailed description of non-limiting embodiments with reference to the accompanying drawings, in which the same or similar reference numerals represent the same or similar features and the accompanying drawings are not drawn to scale.

[0023] Figure 1 A schematic diagram of the structure of a battery management system in related art is shown;

[0024] Figure 2 A schematic diagram showing the structure of an electrical device provided in an embodiment of the present application is shown;

[0025] Figure 3 A schematic structural diagram of a battery pack provided in an embodiment of the present application is shown;

[0026] Figure 4 A schematic diagram showing a circuit structure of a communication circuit provided in an embodiment of the present application is shown;

[0027] Figure 5 Another circuit structure diagram of a communication circuit provided in an embodiment of the present application is shown;

[0028] Figure 6 Another circuit structure diagram of a communication circuit provided in an embodiment of the present application is shown;

[0029] Figure 7Another circuit structure diagram of a communication circuit provided in an embodiment of the present application is shown;

[0030] Figure 8 Another circuit structure schematic diagram of the communication circuit provided in an embodiment of the present application is shown. DETAILED DESCRIPTION

[0031] The features and exemplary embodiments of various aspects of the present application will be described in detail below. To make the objectives, technical solutions, and advantages of the present application more clearly understood, the present application will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only constructed to explain the present application and are not constructed to limit the present application.

[0032] In the present application, when an element is referred to as being “connected” or “electrically connected” to another element, it can be directly connected to the other element or one or more intervening elements may be present therebetween.

[0033] "Electrical connection" includes a communication electrical connection.

[0034] The implementation methods and specific features in the implementation methods provided in the examples of this application can be combined with each other if there is no contradiction.

[0035] The BMS communicates with the vehicle controller of the vehicle through the communication circuit. For example, some car models support one-line communication, and some car models support RS485 communication. When developing the communication technology between BMS and electrical equipment (such as electric vehicles), the applicant found that on the BMS circuit board, both the one-line communication circuit (hereinafter referred to as the one-line communication circuit) and the RS485 communication circuit (hereinafter referred to as the RS485 communication circuit) were laid out to make the BMS circuit board adapt to the communication requirements of different manufacturers. Such a design makes the communication circuit in the BMS more complicated, resulting in high development costs, poor product compatibility and other problems. In addition, the one-line communication circuit and the RS485 communication circuit need to occupy two serial port resources of the controller (MCU), and the occupied MCU resources are also relatively large, that is, the one-line communication circuit requires a pair of sending pins and receiving pins of the MCU, and the RS485 communication circuit also requires another pair of sending pins and receiving pins of the MCU. In addition, in the related technology, such as Figure 1 As shown, the one-line communication circuit in the BMS is set in the negative control scheme of the charge and discharge switch. The negative control scheme of the charge and discharge switch refers to the charge and discharge switch on the BMS circuit board being set between the negative electrode B- of the battery module and the negative output terminal P- of the battery pack (also called the negative control switch). Figure 1The one-line communication circuit is electrically connected to the negative electrode B- of the battery module via the negative control switch K1. Therefore, the one-line communication circuit can only communicate after the negative control switch K1 is closed. Because the reference ground P- of the one-line communication circuit and the negative electrode B- of the battery module are different reference grounds, to ensure normal communication when the negative control switch K1 is disconnected, an additional isolated power supply is required, and isolation is performed by an isolation device (such as an optocoupler). The opening and closing of the isolation device affects the communication speed of the one-line communication. Therefore, the one-line communication circuit in the related art suffers from high cost, large circuit board area occupation, and inability to achieve high-speed communication.

[0036] In order to improve at least one of the above technical problems, the present application provides a communication circuit, a battery management system, a battery pack and an electrical device. The embodiments of the present application will be described below in conjunction with the accompanying drawings.

[0037] like Figure 2 As shown, the electric device 3000 in this embodiment includes a battery pack 1000, and the electric device 3000 includes a load 2000. The battery pack 1000 is electrically connected to the load 2000 to provide electric energy to the load 2000.

[0038] In this application, the power-consuming device 3000 may optionally include electric vehicles, unmanned aerial vehicles, energy storage devices, and electric tools. In some specific implementations, the electric vehicles include electric cars, electric motorcycles, and electric bicycles, and the energy storage devices include household energy storage devices, industrial and commercial energy storage devices, and uninterruptible power supplies (UPS).

[0039] like Figure 3 As shown, the battery pack 1000 includes a battery management system 100, a battery module 200 and a second connector 300. The battery management system 100 is electrically connected to the battery module 200. The battery module 200 includes a plurality of battery cells connected in series, in parallel or in mixed connection. Mixed connection is the connection between battery cells including series and parallel connection.

[0040] The battery management system 100 monitors the parameters of the battery pack 1000, including voltage, current, temperature, etc., and then controls the charge and discharge switches to be turned on or off to manage the charge and discharge of the battery module 200. The battery management system 100 controls the discharge switch to be turned on, and the battery module 200 supplies power to the load 2000. The battery management system 100 controls the charge switch to be turned on, and the charging device charges the battery module 200. It is understandable that when the battery module is normally charged or discharged, the battery management system 100 will control the charge switch and the discharge switch to be in the open state, and the charge switch and the discharge switch are both closed so that electrical energy can be transmitted to the load on the main circuit (power path). When the battery management system 100 monitors the battery pack 1000 for overvoltage, undervoltage, overcurrent, overtemperature and other faults, it controls the charge and discharge switches to be turned off to disconnect the charge and discharge of the battery module 200.

[0041] A second connector 300 is provided on the battery pack 1000. The second connector 300 includes a power port and a signal port. The second connector 300 is used to plug into the first connector 101 on the electrical device 3000, transmit electrical energy to the load on the electrical device 3000 through the power port of the second connector 300, and communicate with the controller on the electrical device 3000 through the signal port of the second connector 300. The signal port of the second connector 300 is electrically connected to the first connector 101 through a communication harness, and the power port of the second connector 300 is electrically connected to the power terminal on the BMS circuit board through a power harness. The power port of the second connector 300 includes a positive output port P+ and a negative output port P-.

[0042] The battery management system 100 includes a communication circuit 10, which includes an isolated communication unit 2. The isolated communication unit 2 includes a first differential pin A and a second differential pin B. The first differential pin A is electrically connected to the first communication port P1 of the first connector 101 via a first communication transmission line, and the second differential pin B is electrically connected to the second communication port P2 of the first connector 101 via a second communication transmission line. The first communication transmission line L1 and the second communication transmission line L2 are printed copper wires on the BMS circuit board.

[0043] In industrial implementation, the second connector 300 can be called the aviation plug of the battery pack, and the communication port of the second connector 300 is electrically connected to the first communication port P1 and the second communication port P2 of the first connector 101 through a signal communication harness. The communication port of the second connector 300 is the communication port (or communication terminal) on the aviation plug. For example, if the aviation plug on the battery pack is a male plug, then the aviation plug on the entire vehicle is a female plug, or if the aviation plug on the battery pack is a female plug, then the aviation plug on the entire vehicle is a male plug. After the aviation plug on the battery pack is plugged into the aviation plug on the entire vehicle, the battery pack supplies power to the entire vehicle, and the battery pack communicates with the entire vehicle through the communication circuit 10.

[0044] like Figure 4 As shown, the communication circuit 10 includes a controller 1 , an isolated communication unit 2 , a first switch unit 31 , a second switch unit 32 , a first power supply V1 , a second power supply V2 , and a first resistor R1 .

[0045] Controller 1 is an integrated circuit with signal processing capabilities and is a key component in a BMS. It controls the charging and discharging of the battery modules based on monitored battery pack parameters. In some embodiments, controller 1 is a general-purpose processor, such as a microcontroller unit (MCU).

[0046] The isolated communication unit 2 is electrically connected to the controller 1. On the BMS circuit board, the electrical connection between the isolated communication unit 2 and the controller 1 is achieved by printing copper wires. The isolated communication unit 2 has the functions of isolation and communication. In the disclosure of this application, the BMS in the battery pack can select one of the first communication mode and the second communication mode to communicate with the outside. Specifically, the controller 1 and the outside (such as the whole vehicle controller) communicate based on the first communication mode through the isolated communication unit 2, or the controller 1 and the outside (such as the whole vehicle controller) communicate based on the second communication mode through the isolated communication unit 2.

[0047] The first switch unit 31 electrically connects the controller 1 and the isolated communication unit 2, and the second switch unit 32 electrically connects the controller 1 and the isolated communication unit 2. The first resistor R1 is electrically connected to the isolated communication unit 2 through the first switch unit 31. The controller 1 controls the on and off states of the first switch unit 31 and the second switch unit 32 to achieve two different communication methods to communicate with the power device. The following briefly describes the communication principle between the battery pack and the outside world:

[0048] The controller 1 sends a first control signal to the first switch unit 31 to control the first switch unit 31 to be disconnected, thereby disconnecting the electrical connection between the first resistor R1 and the isolated communication unit 2. The controller 1 sends a second control signal to the second switch unit 32 to control the second switch unit 32 to be turned on. The first power supply V1 is electrically connected to the isolated communication unit 2 through the turned-on second switch unit 32, and the communication circuit 10 communicates with the outside in the first communication mode.

[0049] The controller 1 sends a second control signal to the first switch unit 31 to control the first switch unit to be turned on, and the first resistor R1 establishes an electrical connection with the isolation communication unit 2 through the first switch unit 31. The controller 1 sends a first control signal to the second switch unit 32 to control the second switch unit to be turned off, and the communication circuit 10 communicates with the outside in the second communication mode.

[0050] In some embodiments, the first control signal sent by the controller 1 to the first switch unit 31 or the second switch unit 32 is a low-level signal, and the second control signal sent by the controller 1 to the first switch unit 31 or the second switch unit 32 is a high-level signal.

[0051] The communication circuit disclosed in this application implements multiple communication modes through a single design, compatible with the communication application requirements of various vehicle models. Both the first and second communication modes are implemented through this communication circuit, thereby reusing components, reducing circuit design complexity, lowering costs, and improving component compatibility. Furthermore, the communication circuit is powered by a first power source and a second power source. Therefore, regardless of whether the battery pack's charge and discharge switches are in a positive or negative control scheme, the on / off switching of the charge and discharge switches does not affect the dynamic switching between the first and second communication modes.

[0052] In one or more embodiments of the present application, Figure 5 As shown, the controller 1 includes a first transmit pin TX, a first receive pin RX, a first control pin DE1, a second control pin EN2, and a third control pin EN3. The first transmit pin TX, the first receive pin RX, and the first control pin DE1 are electrically connected to the isolated communication unit 2, the second control pin EN2 is electrically connected to the second switch unit 32, and the third control pin EN3 is electrically connected to the first switch unit 31.

[0053] Exemplarily, the first transmitting pin TX, the first receiving pin RX, and the first control pin DE1 of the controller 1 are electrically connected to different pins of the isolation communication unit 2 , respectively.

[0054] The controller 1 sends data to the isolated communication unit 2 through the first sending pin TX, and the controller receives data sent from the isolated communication unit 2 through the first receiving pin RX.

[0055] Exemplarily, the isolated communication unit 2 also has the function of receiving and sending data. The controller 1 sends data to the isolated communication unit 2 via the first transmit pin TX, and then the isolated communication unit 2 sends the data sent by the controller 1 to the outside (for example, the controller of the electrical device). The outside (for example, the controller of the electrical device) sends data to the isolated communication unit 2, and the isolated communication unit 2 then sends the data sent by the external to the controller 1 via the first receive pin RX. It is understandable that the isolated communication unit 2 can transmit data based on the first communication mode or the second communication mode.

[0056] The controller 1 sends a control signal to the isolated communication unit 2 via the first control pin DE1 to control the isolated communication unit 2 to be in a data receiving mode or a data transmitting mode. The controller 1 sends a control signal to the second switch unit 32 via the second control pin EN2 to control the second switch unit 32 to be turned on or off. The controller 1 sends a control signal to the first switch unit 31 via the third control pin EN3 to control the first switch unit 31 to be turned on or off.

[0057] In this embodiment, the controller 1 sends data to the outside through the first sending pin TX, receives external data through the first receiving pin RX, and controls the working mode of the isolation communication unit 2, the on-off state of the first switch unit 31, and the on-off state of the second switch unit 32 through the first control pin DE1, the second control pin EN2, and the third control pin EN3, respectively, to realize data transmission between the controller 1 in the BMS and the controller of the electrical device through the first communication mode or the second communication mode.

[0058] In one or more embodiments of the present application, the controller 1 sends different control signals to the isolated communication unit 2 through the first control pin DE1 to control the isolated communication unit 2 to be in a data receiving mode or a data sending mode.

[0059] The controller 1 sends a first control signal to the isolated communication unit 2 through the first pin DE1, the isolated communication unit 2 operates in a working mode of receiving data, and the communication circuit 10 receives external data. The controller 1 sends a second control signal to the isolated communication unit 2 through the first pin DE1, the isolated communication unit 2 operates in a working mode of sending data, and the communication circuit 10 sends data to the outside. It is understandable that in some other embodiments, the controller 1 sends the second control signal to the isolated communication unit 2 through the first pin DE1, the isolated communication unit 2 operates in a working mode of receiving data, and the controller 1 sends the first control signal to the isolated communication unit 2 through the first pin DE1, the isolated communication unit 2 operates in a working mode of sending data. Specifically, the isolated communication unit 2 responds to which control signal (high-level control signal or low-level control signal) to operate in a working state of receiving data or a working state of sending data, depending on the specific selection of the isolated communication unit, and this application does not make specific limitations on this.

[0060] In one or more embodiments of the present application, Figure 5 or Figure 8As shown, the isolated communication unit 2 includes an isolated communication integrated circuit, which is generally presented in the form of an isolated communication chip U1. The isolated communication chip U1 includes a second transmit pin D, a second receive pin R, a first differential pin A, a second differential pin B, a first power pin VCC1, a second power pin VCC2, a drive enable pin DE, and a receive enable pin RE.

[0061] The second transmitting pin D is electrically connected to the first transmitting pin TX of the controller 1. The isolated communication chip U1 receives data transmitted from the first transmitting pin TX of the controller 1 through the second transmitting pin D.

[0062] The second receiving pin R is electrically connected to the first receiving pin RX of the controller 1. The isolated communication chip U1 sends data to the first receiving pin RX of the controller 1 through the second receiving pin R.

[0063] The first differential pin A is electrically connected to the first power source V1 and the first communication port P1 via the first communication transmission line L1. The isolated communication chip U1 receives data from the outside (eg, a controller of an electric device) via the first differential pin A.

[0064] The second differential pin B is electrically connected to the first power source V1 through the second switch unit 32 and is electrically connected to the second communication port P2 through the second communication transmission line L2. The isolated communication chip U1 receives data sent from the outside (such as the controller of the power device) through the second differential pin B.

[0065] The first power pin VCC1 is electrically connected to the first power source V1. The first power source V1 supplies power to the isolated communication chip U1 through the first power pin VCC1.

[0066] The second power pin VCC2 is electrically connected to a second power source V2. The second power source V2 supplies power to the isolated communication chip U1 through the second power pin VCC2.

[0067] The drive enable pin DE is electrically connected to the first control pin DE1 of the controller 1. The receive enable pin RE is electrically connected to the first control pin DE1 of the controller 1. The isolated communication chip U1 receives a control signal from the first control pin DE1 of the controller 1 via the drive enable pin DE and the receive enable pin RE, thereby placing the isolated communication chip U1 in a data receiving mode or a data transmitting mode.

[0068] The first connector 101 includes a first communication port P1 and a second communication port P2. The first connector 101 is connected to the second connector 300 through a communication harness to realize communication connection between the first communication port P1 and the second communication port P2 and the communication port (also called communication terminal) on the second connector 300. After the second connector 300 on the battery pack 1000 is plugged into the connector on the electrical device 3000, the battery pack 1000 can communicate with the electrical device 3000 and complete data interaction.

[0069] When the first switch unit 31 is disconnected and the second switch unit 32 is turned on, the communication circuit 10 communicates with the outside in the first communication mode. The first control pin DE1 of the controller 1 outputs a high-level first control signal, and the isolated communication chip U1 is in data transmission mode. The isolated communication chip U1 sends the data output by the first transmission pin TX of the controller 1 to the first communication transmission line L1. The first communication transmission line L1 transmits the message under the first communication mode. The message is transmitted through the first connector 101, the communication harness in the battery pack (not shown), the second connector 300, and the connector on the power-consuming device 3000, and is used to be recognized by the controller of the power-consuming device (such as the controller of the entire vehicle). The first control pin DE1 of the controller 1 outputs a low-level first control signal, and the isolated communication chip U1 is in data receiving mode. The controller of the electrical device (for example, the controller of the entire vehicle) sends high and low levels to the first communication transmission line L1 through the connector on the electrical device 3000, the second connector 300, the communication harness in the battery pack, and the first connector 101. Since the second switch unit 32 is turned on, the second communication transmission line L2 is at a fixed level. The isolated communication chip U1 receives the differential level through the first differential pin A and the second differential pin B, and sends data from the outside to the first receiving pin RX of the controller 1.

[0070] In this embodiment, the second transmitting pin D of the isolated communication chip U1 can receive data output by the first transmitting pin TX of the controller 1, and the second receiving pin R of the isolated communication chip U1 can send data to the first receiving pin RX of the controller 1. The first differential pin A and the second differential pin B exchange data with the controller of the electrical device through the first connector 101. The driver enable pin DE and the receive enable pin RE receive the control signal of the first control pin DE1 of the controller 1, thereby controlling the working mode of the isolated communication chip U1. Communication between the controller 1 and the controller of the electrical device is realized through the isolated communication chip U1, signal transmission lines L1 and L2, the first connector 101, and the connector 300.

[0071] In one or more embodiments of the present application, Figure 6 or Figure 7As shown, the first switch unit 31 includes a first switch, the first switch includes a photo MOSFET Q1, and the photo MOSFET Q1 includes a first input terminal and a first output terminal.

[0072] The first pin 1 of the first input terminal of the optical MOSFET Q1 is electrically connected to the third control pin EN3 of the controller 1, and the second pin 2 of the first input terminal is electrically connected to the first reference ground GND1. Figure 6 As shown, the first resistor R1 is electrically connected between the third pin 3 of the optical MOSFET Q1 and the first differential pin A. Alternatively, as Figure 7 As shown, the first resistor R1 is electrically connected between the fourth pin 4 and the second differential pin B of the photo MOSFET Q1.

[0073] Figure 6 and Figure 7 In the embodiment, the third pin 3 of the first output terminal of the photo MOSFET Q1, the fourth pin 4 of the first output terminal and the first resistor R1 are connected in series between the first differential pin A and the second differential pin B.

[0074] Optionally or additionally, the first resistor R1 is a terminal resistor (also called a terminal matching resistor or a terminal load resistor). When the third control pin EN3 of the controller 1 outputs a low level, the optical MOSFET Q1 is disconnected, and the electrical connection between the first resistor R1 and the isolation communication chip U1 is disconnected.

[0075] When the third control pin EN3 of the controller 1 outputs a high level, the optical MOSFET Q1 is turned on, and an electrical connection between the first resistor R1 and the isolation communication chip U1 is established.

[0076] For example, the resistance of the first resistor R1 can be in the hundreds of ohms range, with 120Ω being a typical application. Because the voltages connected to the first differential pin A and the second differential pin B are differential, if a photocoupler is used as the first switch, it is susceptible to breakdown due to its relatively low reverse voltage withstand. Optical MOSFETs, on the other hand, have bidirectional blocking capabilities and can have the same withstand voltage. Therefore, using an optical MOSFET as the first switch can prevent overload damage to the optical MOSFET, thereby improving the reliability of the communication circuit.

[0077] Alternatively or additionally, such as Figure 6 or Figure 7 As shown, the second switch unit 32 may further include a second switch Q2 , an isolation element U2 , a second resistor R2 , and a third resistor R3 .

[0078] The first power source V1 is electrically connected to the first end of the second resistor R2 via the second switch Q2. The second end of the second resistor R2, the second differential pin B, and the first end of the third resistor R3 are electrically connected to the first node. The second end of the third resistor R3 is electrically connected to the second reference ground GND2. When the second switch Q2 is on, the power of the first power source V1 is divided by the second resistor R2 and the third resistor R3, and the second differential pin B receives a fixed voltage. The voltage received by the second differential pin B is greater than 0V and less than the voltage of the first power source V1. When the second switch Q2 is off, the second differential pin B receives a voltage signal via the second communication port P2.

[0079] The isolated communication chip U1 includes a first ground pin GND11 and a second ground pin GND12. The first ground pin GND11 is electrically connected to the second reference ground GND2, and the second ground pin GND12 is electrically connected to the first reference ground GND1. Exemplarily, the voltage of the first reference ground GND1 relative to the second power supply V2 is 0V. The first reference ground GND1 is electrically connected to the negative terminal B- of the battery pack. The second reference ground GND2 has the same potential as the negative output terminal P- of the battery pack. The voltage of the second reference ground GND2 relative to the first power supply V1 is 0V.

[0080] The isolation element U2 includes a second input and a second output. A first pin 1 of the second input of the isolation element U2 is electrically connected to the second control pin EN2, a second pin 2 of the second input is electrically connected to the first reference ground GND1, a third pin 3 of the second output of the isolation element U2 is electrically connected to the second reference ground GND2, and a fourth pin 4 of the second output is electrically connected to the control terminal of the second switch Q2. The isolation element U2 is used to control the conduction or disconnection of the second switch Q2. When the second control pin EN2 of the controller 1 outputs a high level, the isolation element U2 is turned on, thereby turning on the second switch Q2. When the second control pin EN2 of the controller 1 outputs a low level, the isolation element U2 is turned off, thereby turning off the second switch Q2.

[0081] In one or more embodiments of the present application, the isolation element U2 includes a photocoupler or a photo MOSFET. The drawings of the present application illustrate the isolation element U2 as a photocoupler, which is not intended to limit the present application.

[0082] Exemplarily, the second switch Q2 includes a transistor, for example, a PNP transistor or a P-type FET.

[0083] Alternatively or additionally, such as Figure 6 or Figure 7As shown, the second switch unit 32 may further include a fourth resistor R4 and a fifth resistor R5. A first end of the fourth resistor R4 is electrically connected to the fourth pin 4 of the second output terminal of the isolation element U2, and a second end of the fourth resistor R4 is electrically connected to the control terminal of the second switch Q2. A first end of the fifth resistor R5 is electrically connected to the first power supply V1, and a second end of the fifth resistor R5 is electrically connected to the control terminal of the second switch Q2. The base of the second switch Q2 serves as its control terminal, the emitter of the second switch Q2 is electrically connected to the first power supply V1, and the collector of the second switch Q2 is electrically connected to the second resistor R2.

[0084] When the isolation element U2 is turned on, the fourth resistor R4 and the fifth resistor R5 divide the voltage, so that the second switch Q2 is turned on.

[0085] In the present application, the first communication mode includes one-line communication, and the second communication mode includes RS485 communication.

[0086] The communication circuit in this application supports both one-line communication and RS485 communication, and is suitable for application scenarios where the lithium battery BMS system communicates with the entire vehicle. This communication circuit supports two communication methods and has the advantages of strong adaptability, flexible application, wide application range, and low cost. In addition, the isolated communication chip U1 includes a first differential pin A and a second differential pin B. The isolated communication chip U1 receives and sends data in a differential manner, with a high communication rate.

[0087] Of course, in other examples, those skilled in the art may appropriately modify the communication circuit provided in the embodiment of the present application so that the communication circuit supports other communication modes besides one-line communication and RS485 communication.

[0088] Alternatively or additionally, the resistance of the second resistor R2 and the resistance of the third resistor R3 may satisfy the following relationship:

[0089] |V A -V B |≥200mV;

[0090] V B =(V1×R3) / (R2+R3);

[0091] Wherein, V1 is defined as the voltage of the first power supply V1, V A and V B It is defined as: when the first switch unit 31 is off and the second switch unit 32 is on, the voltage of the first differential pin A is V A , the voltage of the second differential pin B is V B .

[0092] It is understandable that when the first switch unit 31 is turned off and the second switch unit 32 is turned on, the voltage VB is the voltage divided by the third resistor R3 on the first power source V1.

[0093] Exemplarily, the isolated communication chip U1 is a differential transceiver. Whether the differential transceiver can correctly identify a signal depends on whether the differential voltage between the first differential pin A and the second differential pin B exceeds a specified threshold.

[0094] In V A -V B When ≥+200mV, the isolated communication chip U1 recognizes it as logic 1.

[0095] In V A -V B When ≤-200mV, the isolated communication chip U1 recognizes it as logic 0.

[0096] Logic 1 represents a high level, and logic 0 represents a low level.

[0097] If the differential voltage between the first differential pin A and the second differential pin B is between -200 mV and +200 mV, the output of the isolated communication chip U1 may be uncertain (depending on the design of the isolated communication chip U1 ).

[0098] Therefore, the absolute condition for the isolated communication chip U1 to correctly identify the signal is: |V A -V B |≥200mV.

[0099] In the one-line communication mode, isolation element U2 and second switch Q2 are turned on, second differential pin B is connected to a fixed voltage level, and first differential pin A receives an externally transmitted high-level voltage signal or a low-level voltage signal. In this embodiment, when the resistance values ​​of second resistor R2 and third resistor R3 satisfy the aforementioned relationship, the isolated communication chip U1 can implement the one-line communication function based on the flipped voltage level connected to first differential pin A and the fixed voltage level connected to second differential pin B.

[0100] Alternatively or additionally, such as Figure 8 As shown, the communication circuit 10 may further include at least one of a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12, and a thirteenth resistor R13, and the isolated communication unit includes an isolated communication chip U1.

[0101] The sixth resistor R6 is disposed on the second communication transmission line L2 , and the second differential pin B of the isolation communication chip U1 is electrically connected to the second communication port P2 through the sixth resistor R6 .

[0102] The seventh resistor R7 is disposed on the first communication transmission line L1 , and the first differential pin A of the isolation communication chip U1 is electrically connected to the first communication port P1 through the seventh resistor R7 .

[0103] The second sending pin D of the isolated communication chip U1 is electrically connected to the first sending pin TX of the controller 1 through the eighth resistor R8.

[0104] The second switch unit 32 is electrically connected to the second control pin EN2 of the controller 1 via a ninth resistor R9 .

[0105] The second receiving pin R of the isolated communication chip U1 is electrically connected to the first receiving pin RX of the controller 1 through a tenth resistor R10 .

[0106] The driving enable pin DE and the receiving enable pin RE of the isolated communication chip U1 are electrically connected to the first control pin DE1 of the controller 1 through the eleventh resistor R11 .

[0107] The first switch unit 31 is electrically connected to the third control pin EN3 of the controller 1 through the twelfth resistor R12 .

[0108] The first differential pin A of the isolated communication chip U1 is electrically connected to the first power source V1 through a thirteenth resistor R13 .

[0109] The sixth resistor R6, the seventh resistor R7, the eighth resistor R8, the ninth resistor R9, the tenth resistor R10, the eleventh resistor R11, the twelfth resistor R12, and the thirteenth resistor R13 all serve as current limiting resistors to protect the ports or pins to which they are electrically connected and improve the reliability of the communication circuit.

[0110] Alternatively or additionally, such as Figure 8 As shown, the communication circuit may further include a fourteenth resistor R14, the isolated communication unit includes an isolated communication chip U1, and the second receiving pin R of the isolated communication chip U1 is electrically connected to the second power supply V2 through the fourteenth resistor R14. The fourteenth resistor R14 can be used for current limiting to protect the second receiving pin R of the isolated communication chip U1;

[0111] And / or, the communication circuit also includes a fifteenth resistor R15, and the drive enable pin DE and the receive enable pin RE of the isolated communication chip U1 are electrically connected to the first reference ground GND1 through the fifteenth resistor R15. The fifteenth resistor R15 can be used to limit current to protect the drive enable pin DE and the receive enable pin RE of the isolated communication chip U1, thereby improving the reliability of the communication circuit.

[0112] Alternatively or additionally, such as Figure 8As shown, the communication circuit may further include a first transient voltage suppression diode D1, a first end of the first transient voltage suppression diode D1 being electrically connected to the second differential pin B of the isolation communication chip U1, and a second end of the first transient voltage suppression diode D1 being electrically connected to the second reference ground GND2.

[0113] Optionally or additionally, the communication circuit may further include a second transient voltage suppression diode D2, the first end of the second transient voltage suppression diode D2 being electrically connected to the second differential pin B of the isolated communication chip U1, and the second end of the second transient voltage suppression diode D2 being electrically connected to the first differential pin A of the isolated communication chip U1.

[0114] Optionally or additionally, the communication circuit may further include a third transient voltage suppression diode D3 having a first end electrically connected to the first differential pin A of the isolation communication chip U1 and a second end electrically connected to the second reference ground GND2.

[0115] When transient high voltage (such as surges caused by ESD, EMC, lightning strikes, and inductive load switching) occurs in the circuit, transient voltage suppression diodes (TVS) can quickly turn on (with a response time of up to picoseconds), clamping the voltage within a safe range and preventing damage to the communication circuit, thereby improving the reliability and stability of the communication circuit.

[0116] Alternatively or additionally, such as Figure 8 As shown, the communication circuit may further include a first capacitor C1, a first end of the first capacitor C1 is electrically connected to the first reference ground GND1, and a second end of the first capacitor C1 is electrically connected to the second power supply V2; and / or, the communication circuit may further include a second capacitor C2, a first end of the second capacitor C2 is electrically connected to the second reference ground GND2, and a second end of the second capacitor C2 is electrically connected to the first power supply V1.

[0117] The capacitor connected between the power supply and the reference ground can be used to stabilize the power supply voltage, filter noise, provide transient current, etc., which can further improve the reliability of the communication circuit.

[0118] The following example uses the isolated communication chip U1 as an RS485 transceiver, the first communication mode includes one-line communication, and the second communication mode includes RS485 communication. Figure 8 , introduces the working principle of communication circuit:

[0119] When the second control pin EN2 of the controller 1 outputs a high level and the third control pin EN3 of the controller 1 outputs a low level, the optical MOSFET Q1 is disconnected, the isolation element U2 is turned on, the second switch Q2 is turned on, the first resistor R1 is not connected, the second differential pin B is at a fixed level, and the communication circuit communicates with the outside in a one-line communication mode.

[0120] When communicating in a one-line communication mode, when the first control pin DE1 of the controller 1 outputs a high level, the isolated communication chip U1 enters the sending mode, and the first sending pin TX of the controller 1 sends a one-line notification message, and a high and low level are formed on the first differential pin A, which is then recognized by the vehicle controller connected to the first connector 101.

[0121] When communicating in a one-line communication mode, when the first control pin DE1 of the controller 1 outputs a low level, the isolated communication chip U1 enters the receiving mode, and the vehicle controller sends high and low levels to the first differential pin A through the first communication transmission line l1 (the high level is equal to the level of the first power supply V1, and the low level is 0V). Since the second differential pin B is a fixed level, the isolated communication chip U1 obtains the differential level between the first differential pin A and the second differential pin B. When the first differential pin A is high, the differential level between the first differential pin A and the second differential pin B is a positive voltage. When the first differential pin A is low (0V), the differential level between the first differential pin A and the second differential pin B is a negative voltage. Therefore, the isolated communication chip U1 can flip according to the level state on the first differential pin A to realize the one-line receiving function.

[0122] When the second control pin EN2 of the controller 1 outputs a low level and the third control pin EN3 of the controller 1 outputs a high level, the optical MOSFET Q1 is turned on, the isolation element U2 is turned off, the second switch Q2 is turned off, the first resistor R1 is connected to the first differential pin A and the second differential pin B, and the communication circuit communicates with the outside in RS485 communication mode.

[0123] When communicating in RS485 communication mode, when the first control pin DE1 of the controller 1 outputs a high level, the isolated communication chip U1 enters the sending mode, the first sending pin TX of the controller 1 sends the RS485 message, and high and low levels are formed on the first differential pin A and the second differential pin B, which are then recognized by the vehicle controller connected to the first connector 101.

[0124] When communicating in RS485 communication mode, when the first control pin DE1 of the controller 1 outputs a low level, the isolated communication chip U1 enters the receiving mode, and the vehicle controller sends high and low levels to the first differential pin A and the second differential pin B (the high level is equal to the level of the first power supply V1, and the low level is 0V). The isolated communication chip U1 obtains the differential level between the first differential pin A and the second differential pin B. When the first differential pin A is high and the second differential pin B is low, the differential level between the first differential pin A and the second differential pin B is a positive voltage. When the first differential pin A is low and the second differential pin B is high, the differential level between the first differential pin A and the second differential pin B is a negative voltage. Therefore, the isolated communication chip U1 can flip according to the level state on the first differential pin A to realize the RS485 receiving function.

[0125] It is understandable that whether communicating by one-line communication or RS485, the differential isolation communication chip U1 is used, which does not require the response time of the switch in the one-line communication circuit in the related technology and can achieve high-speed communication.

[0126] In summary, the present application realizes the one-line isolated communication function and the RS485 isolated communication function through the isolated communication chip U1. The communication function is not affected by the on / off status of the positive control switch and the negative control switch in the battery pack, and the communication circuit of the present application has its own pull-up and pull-down functions (the first power supply V1 is electrically connected to the first differential pin A, and the second reference ground GND2 is electrically connected to the second differential pin B to realize the pull-up and pull-down functions). There is no need to adapt external parameters and it can meet high-speed communication requirements.

[0127] The communication circuit provided in the embodiment of the present application can realize dynamic switching between one-line communication and RS485 communication without changing the external communication port, thereby improving the adaptability of the communication circuit.

[0128] The communication circuit provided in the embodiment of the present application may also include current limiting resistors, transient suppression diodes, filter capacitors, etc., so that the communication circuit has protection capabilities such as anti-high voltage abuse and EMC protection performance, thereby ensuring the reliability and stability of the communication circuit.

[0129] The communication circuit provided in the embodiment of the present application can be applied to the application scenario of low-cost communication interaction between the lithium battery BMS system and the whole vehicle. It has the advantages of strong adaptability, high communication rate, flexible application, wide application range and low cost. It can improve the problems of complex communication circuit design, poor adaptability and low communication rate in related technologies.

[0130] It should be noted that in the embodiments shown in the above figures, the resistor is represented as a single resistor, and the capacitor is represented as a single capacitor. In other embodiments, the resistor may be an integration of resistors connected in series, in parallel, or in a hybrid configuration, and the capacitor may be an integration of capacitors connected in series, in parallel, or in a hybrid configuration. The specific parameters of each device may be set according to actual needs, and this application does not limit this.

Claims

1. A communication circuit, characterized in that: include: Controller; an isolation communication unit, electrically connected to the controller; a first switch unit, electrically connecting the controller and the isolation communication unit; a second switch unit, electrically connecting the controller and the isolation communication unit; a first power supply and a second power supply, the first power supply being electrically connected to the second switch unit and the isolated communication unit, and the second power supply being electrically connected to the isolated communication unit; a first resistor, electrically connected to the isolation communication unit through the first switch unit; The communication circuit is configured to: In response to the controller sending a first control signal to the first switch unit, the first switch unit is turned off, the controller sends a second control signal to the second switch unit, the second switch unit is turned on, and the communication circuit communicates with the outside in the first communication mode; In response to the controller sending the second control signal to the first switch unit, the first switch unit is turned on, the controller sends the first control signal to the second switch unit, the second switch unit is turned off, and the communication circuit communicates with the outside in the second communication mode; The first communication mode is different from the second communication mode.

2. The communication circuit according to claim 1, wherein: The controller includes: A first sending pin, electrically connected to the isolation communication unit; A first receiving pin, electrically connected to the isolation communication unit; A first control pin, electrically connected to the isolation communication unit; a second control pin, electrically connected to the second switch unit; The third control pin is electrically connected to the first switch unit.

3. The communication circuit according to claim 2, wherein: The communication circuit is configured to: In response to the controller sending the first control signal to the isolated communication unit through the first control pin, the communication circuit receives external data; In response to the controller sending the second control signal to the isolated communication unit through the first control pin, the communication circuit sends data to the outside.

4. The communication circuit according to claim 2 or 3, characterized in that: The isolated communication unit includes an isolated communication chip, and the isolated communication chip includes: a second sending pin, electrically connected to the first sending pin; a second receiving pin, electrically connected to the first receiving pin; a first differential pin electrically connected to the first power source, wherein the first differential pin is configured to be electrically connected to a first communication port through a first communication transmission line; a second differential pin, electrically connected to the first power supply through the second switch unit, and the second differential pin is configured to be electrically connected to a second communication port through a second communication transmission line; a first power pin, electrically connected to the first power source; a second power supply pin, electrically connected to the second power supply; a drive enable pin electrically connected to the first control pin; A receiving enable pin is electrically connected to the first control pin.

5. The communication circuit according to claim 4, characterized in that The first switch unit includes a first switch, the first switch includes a photo MOSFET, and the photo MOSFET includes a first input terminal and a first output terminal; wherein, The first pin of the first input terminal is electrically connected to the third control pin, and the second pin of the first input terminal is electrically connected to the first reference ground; The third pin of the first output end, the fourth pin of the first output end, and the first resistor are connected in series between the first differential pin and the second differential pin.

6. The communication circuit according to claim 4 or 5, characterized in that: The second switch unit includes: a second switch, an isolation element, a second resistor and a third resistor; The first power source is electrically connected to the first end of the second resistor through the second switch, the second end of the second resistor, the second differential pin, and the first end of the third resistor are electrically connected to the first node, and the second end of the third resistor is electrically connected to the second reference ground; The isolated communication chip includes a first ground pin and a second ground pin, the first ground pin is electrically connected to a first reference ground, and the second ground pin is electrically connected to a second reference ground; The isolation element includes a second input terminal and a second output terminal; wherein, The first pin of the second input terminal is electrically connected to the second control pin, and the second pin of the second input terminal is electrically connected to the first reference ground; The third pin of the second output end is electrically connected to the second reference ground, and the fourth pin of the second output end is electrically connected to the control end of the second switch.

7. The communication circuit according to claim 6, characterized in that The second switch unit further includes a fourth resistor and a fifth resistor; The fourth pin of the second output end is electrically connected to the control end of the second switch through the fourth resistor, and the fifth resistor is electrically connected between the first power source and the control end of the second switch.

8. The communication circuit according to claim 6 or 7, characterized in that: The resistance value R2 of the second resistor and the resistance value R3 of the third resistor satisfy the following relationship: |V A -V B |≥200mV; In B =(V1×R3) / (R2+R3); Wherein, V1 is defined as the voltage of the first power supply, V A and V B Defined as: when the first switch unit is off and the second switch unit is on, the voltage of the first differential pin is V A , the voltage of the second differential pin is V B .

9. The communication circuit according to any one of claims 6 to 8, characterized in that: The isolation element includes a photocoupler or a photo MOSFET, and the second switch includes a PNP transistor or a P-type FET.

10. The communication circuit according to any one of claims 1 to 9, characterized in that: The first communication mode includes one-line communication, and the second communication mode includes RS485 communication.

11. The communication circuit according to any one of claims 1 to 10, characterized in that: The communication circuit further includes at least one of a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a tenth resistor, an eleventh resistor, a twelfth resistor, and a thirteenth resistor; wherein the isolated communication unit includes an isolated communication chip; The second differential pin of the isolated communication chip is configured to be electrically connected to the second communication port through the sixth resistor; The first differential pin is configured to be electrically connected to the first communication port through the seventh resistor; The second sending pin of the isolation communication chip is electrically connected to the first sending pin of the controller through the eighth resistor; The second switch unit is electrically connected to the second control pin of the controller through the ninth resistor; The second receiving pin of the isolation communication chip is electrically connected to the first receiving pin of the controller through the tenth resistor; The driving enable pin and the receiving enable pin of the isolated communication chip are electrically connected to the first control pin of the controller through the eleventh resistor; The first switch unit is electrically connected to the third control pin of the controller through the twelfth resistor; The first differential pin of the isolated communication chip is electrically connected to the first power supply through the thirteenth resistor.

12. The communication circuit according to any one of claims 1 to 10, characterized in that: The communication circuit further includes a fourteenth resistor; wherein the isolated communication unit includes an isolated communication chip; The second receiving pin of the isolated communication chip is electrically connected to the second power supply through the fourteenth resistor; And / or, the communication circuit further includes a fifteenth resistor; The driving enable pin and the receiving enable pin of the isolated communication chip are electrically connected to the first reference ground through the fifteenth resistor.

13. The communication circuit according to any one of claims 1 to 12, characterized in that: The communication circuit further includes at least one of a first transient voltage suppression diode, a second transient voltage suppression diode, and a third transient voltage suppression diode; wherein the isolated communication unit includes an isolated communication chip; A first end of the first transient voltage suppression diode is electrically connected to the second differential pin of the isolation communication chip, and a second end of the first transient voltage suppression diode is electrically connected to a second reference ground; A first end of the second transient voltage suppression diode is electrically connected to the second differential pin of the isolation communication chip, and a second end of the second transient voltage suppression diode is electrically connected to the first differential pin; A first end of the third transient voltage suppression diode is electrically connected to the first differential pin of the isolated communication chip, and a second end of the third transient voltage suppression diode is electrically connected to the second reference ground.

14. The communication circuit according to any one of claims 1 to 13, characterized in that: The communication circuit further includes at least one of a first capacitor and a second capacitor; A first end of the first capacitor is electrically connected to a first reference ground, and a second end of the first capacitor is electrically connected to the second power supply; A first end of the second capacitor is electrically connected to a second reference ground, and a second end of the second capacitor is electrically connected to the first power supply.

15. A battery management system, characterized in that: comprising a first connector and a communication circuit according to any one of claims 1 to 14; The first connector includes a first communication port and a second communication port; The isolated communication unit includes: a first differential pin electrically connected to the first communication port via a first communication transmission line; The second differential pin is electrically connected to the second communication port through a second communication transmission line.

16. A battery pack, characterized in that: comprising a second connector, a battery module, and the battery management system as claimed in claim 15; The second connector is electrically connected to the first connector via a communication harness.

17. An electrical device, characterized in that: Comprising the battery pack as claimed in claim 16.

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