Constant current source and constant current source circuit board

Abstract

This application provides a constant current source and a constant current source circuit board. The constant current source includes an isolated power supply module, an isolated CAN communication module, a microcontroller control module, a sampling module, and a constant current control module. The isolated power supply module includes a power conversion module and an optocoupler controller. The power conversion module electrically isolates its input and output terminals. The input terminal of the power conversion module is connected to the output terminal of the power supply device, allowing the microcontroller control module to control its switching. The isolated CAN communication module includes an isolated CAN transceiver and a CAN bus protection circuit. The constant current control module is connected to the isolated power supply module and outputs based on a preset value. The sampling module is located at the output terminal of the constant current control module to acquire the current value at the output terminal of the constant current control module. The microcontroller control module adjusts the output of the constant current control module based on the current value through feedback until the preset value is reached.

Description

Technical Field

[0001] This application relates to the field of current control technology, and in particular to a constant current source and a constant current source circuit board. Background Technology

[0002] In existing constant current source technologies, reliability and anti-interference capabilities are often low when facing complex electromagnetic environments. Existing technologies are susceptible to external electromagnetic interference, leading to unstable output current and an inability to accurately maintain the preset value.

[0003] Therefore, there is an urgent need for a constant current source with stronger anti-interference capabilities. Summary of the Invention

[0004] In order to overcome the above-mentioned defects, the present invention is proposed to provide a solution or at least a partial solution to the problem of poor anti-interference capability of constant current sources in the prior art.

[0005] In a first aspect, embodiments of this application provide a constant current source, comprising: an isolated power supply module, an isolated CAN communication module, a microcontroller control module, a sampling module, and a constant current control module; wherein, the isolated power supply module includes a power conversion module and an optocoupler controller, the input terminal of the power conversion module is the input terminal of the isolated power supply module, and the output terminal of the power conversion module is the output terminal of the isolated power supply module, the power conversion module electrically isolates the input terminal and the output terminal of the power conversion module; the input terminal of the power conversion module is connected to the output terminal of the power supply device, the output terminal of the power conversion module is connected to the constant current control module, and the control terminal of the power conversion module is connected to the microcontroller control module through the optocoupler controller. The power conversion module is controlled by a microcontroller control module to open and close. The isolated CAN communication module includes an isolated CAN transceiver and a CAN bus protection circuit. The isolated CAN transceiver isolates the primary and secondary sides of the CAN transceiver. The primary side is connected to the microcontroller control module, and the secondary side is connected to the host computer through the CAN bus protection circuit and the CAN bus. The constant current control module is connected to the isolated power supply module and outputs based on a preset value. The sampling module is located at the output of the constant current control module and is used to obtain the current value at the output of the constant current control module. The microcontroller control module adjusts the output of the constant current control module based on the current value through feedback until the preset value is reached.

[0006] As an alternative or supplement to the above solutions, in a method according to an embodiment of the present invention, the isolated CAN transceiver includes a transformer driver, a rectifier module, a signal isolation module, and a signal conversion module; wherein, the transformer driver acquires a DC signal and converts the DC signal into a high-frequency signal, which is input to the primary winding of the transformer, and the secondary winding of the transformer is connected to the rectifier module. The rectifier module acquires the output voltage of the secondary winding of the transformer and outputs a DC voltage, wherein the DC voltage is used to power the signal isolation module and the signal conversion module; one end of the signal isolation module serves as the primary side of the isolated CAN transceiver and is connected to the microcontroller control module, and the other end is connected to the first end of the signal conversion module; the second end of the signal conversion module serves as the secondary side of the isolated CAN transceiver, wherein the signal isolation module is used to electrically isolate the transmitted and received signals, and the signal conversion module converts the CAN signal on the CAN bus into and from logic level signals, wherein the logic level signals are signals that the microcontroller control module can directly understand.

[0007] As an alternative or supplement to the above solutions, in a method according to an embodiment of the present invention, the CAN bus protection circuit includes: a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, a TVS diode, a common-mode inductor, and a terminating resistor; the common-mode inductor includes: port 1, port 2, port 3, and port 4, wherein ports 1 and 2 are connected to the CAN bus as output terminals of the common-mode inductor, and ports 3 and 4 are connected to the output terminal of the isolated CAN transceiver as input terminals of the common-mode inductor, the output terminal of the isolated CAN transceiver outputs a differential signal; the first capacitor... The first and second capacitors are connected in series, and the series-connected first and second capacitors are connected in parallel between the output terminal of the isolated CAN transceiver and the input terminal of the common-mode inductor, with the midpoint of the first and second capacitors connected to ground; the third and fourth capacitors are connected in series, and the series-connected third and fourth capacitors are connected in parallel with the output terminal of the common-mode inductor, with the midpoint of the third and fourth capacitors connected to ground; the TVS diode is connected in parallel with the output terminal of the common-mode inductor, and the terminating resistor is connected in parallel with the output terminal of the common-mode inductor.

[0008] As an alternative or supplement to the above solutions, in a method according to an embodiment of the present invention, the microcontroller control module adjusts the output of the constant current control module to a preset value at least based on the current value through feedback, including: the microcontroller control module obtains the voltage value at the output terminal of the constant current control module, and adjusts the output of the constant current control module to a preset value based on the current value and the voltage value.

[0009] As an alternative or supplement to the above solutions, in a method according to an embodiment of the present invention, the constant current control module includes: a core constant current module, a relay, and a relay driving circuit, wherein the relay is connected to the output terminal of the core constant current module, and when the relay is in different positions, the output terminal of the core constant current module is connected to different circuits; the core constant current module further includes a first control terminal and a second control terminal, the first control terminal is used to receive a voltage control signal from the microcontroller control module, and the second control terminal is used to receive a current control signal from the microcontroller control module, the voltage control signal and the current control signal are respectively used to control the output current and the output current of the core constant current module; the relay driving circuit is used to receive a control signal from the microcontroller control module to drive the relay to switch positions, and the relay driving circuit further includes a freewheeling diode connected in parallel with the relay coil side.

[0010] As an alternative or supplement to the above solutions, in a method according to an embodiment of the present invention, the isolated power supply module further includes: a first power supply module and a second power supply module. The first power supply module converts the input voltage into a first preset voltage, and the second power supply module converts the first preset voltage into a second preset voltage. The first preset voltage is used to provide voltage to the isolated CAN communication module and the constant current source control module, and the second preset voltage is used to provide voltage to the isolated CAN communication module, the microcontroller control module, and the sampling module. The first power supply module is an isolation element that isolates the input voltage received by the first power supply module from the preset voltages output by the first power supply module and the second power supply module.

[0011] As an alternative or supplement to the above solutions, in a method according to an embodiment of the present invention, the isolated CAN communication module further includes: the fifth capacitor and the sixth capacitor, wherein the capacitance value of the sixth capacitor is greater than the capacitance value of the fifth capacitor; wherein one end of the fifth capacitor is connected to the output terminal of the first power supply module, and the other end is connected to ground; one end of the sixth capacitor is connected to the output terminal of the second power supply module, and the other end is connected to ground.

[0012] Secondly, this application provides a constant current source circuit board, which includes: a first layer, a wiring layer, a ground layer and a second layer arranged sequentially from top to bottom; an isolated power supply module, an isolated CAN communication module and a constant current control module are located on the side of the first layer away from the second layer, and a microcontroller control module and a sampling module are located on the side of the second layer away from the first layer; the output terminal of a power supply device is connected in the first layer, and the power supply device is used to supply power to the isolated power supply module.

[0013] As an alternative or supplement to the above solutions, in a method according to an embodiment of the present invention, the ground layer includes a signal ground and a power ground, wherein the signal ground and the power ground are separately disposed and are connected at a single point.

[0014] As an alternative or supplement to the above solutions, in a method according to an embodiment of the present invention, the sampling module includes: a sampling resistor and a differential operational amplifier, wherein the input terminal wire of the differential operational amplifier is connected to both ends of the sampling resistor and acquires the voltage signal of the sampling resistor, and the endpoints of the input terminal wire are respectively located on two solder joints of the sampling resistor.

[0015] The above-described technical solutions of the present invention have at least one or more of the following beneficial effects:

[0016] In implementing the technical solution of this invention, the electrical isolation design of the isolated power supply module effectively improves the anti-interference capability of the constant current source in complex electromagnetic environments and ensures the stability of the output current; the isolated CAN communication module achieves high reliability of signal transmission and data integrity, and enhances the anti-interference performance of communication; the feedback linkage between the sampling module and the microcontroller control module achieves high-precision adjustment of the output current, ensuring that the current is consistent with the preset value; the design of the above modules improves the overall stability and reliability of the constant current source. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of an internal module of a constant current source provided in an embodiment of this application;

[0018] Figure 2 This is a schematic diagram of the structure of an isolated power supply module provided in an embodiment of this application;

[0019] Figure 3 This is a schematic diagram of the internal circuit of an isolated CAN communication module provided in an embodiment of this application;

[0020] Figure 4 This is a schematic diagram of the internal structure of an isolated CAN transceiver provided in an embodiment of this application;

[0021] Figure 5 This is a schematic diagram of the internal structure of a single-chip microcomputer control module provided in an embodiment of this application;

[0022] Figure 6 This is a circuit diagram of a constant current control module provided in an embodiment of this application;

[0023] Figure 7 This is a schematic diagram of the circuit structure of a sampling module provided in an embodiment of this application;

[0024] Figure 8a This is a schematic diagram of the structure of a first power supply module provided in an embodiment of this application;

[0025] Figure 8b This is a schematic diagram of the structure of a second power supply module provided in an embodiment of this application;

[0026] Figure 9 This is a schematic diagram of the structure of a constant current source circuit board provided in an embodiment of this application;

[0027] Figure 10 This is a schematic diagram of a stratum provided in an embodiment of this application;

[0028] Figure 11 This is a schematic diagram of a portion of the structure of a sampling module provided in an embodiment of this application;

[0029] List of reference numerals in the attached diagram:

[0030] 1. First layer; 2. Wiring layer; 3. Ground layer; 4. Second layer; 5. Signal ground; 6. Power ground; 7. Short bridge; 8. Sampling resistor; 9. Wire; 10. Solder joint; 11. Input wire. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be described below with reference to the accompanying drawings.

[0032] The terminology used in the following embodiments is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. As used in the specification and appended claims of this application, the singular expressions “a,” “an,” “the,” “the,” “the,” and “this” are intended to also include expressions such as “one or more,” unless the context clearly indicates otherwise. It should also be understood that in the following embodiments of this application, “at least one” and “one or more” refer to one or more (including two). The term “and / or” is used to describe the relationship between related objects, indicating that three relationships can exist; for example, A and / or B can indicate: A alone, A and B simultaneously, or B alone, where A and B can be singular or plural. The character “ / ” generally indicates that the preceding and following related objects are in an “or” relationship.

[0033] References to "one embodiment" or "some embodiments" as used in this specification mean that one or more embodiments of this application include a specific feature, structure, or characteristic described in connection with that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this specification do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized. The terms "comprising," "including," "having," and variations thereof mean "including but not limited to," unless otherwise specifically emphasized. The term "connection" includes both direct and indirect connections, unless otherwise stated.

[0034] Hereinafter, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.

[0035] In the embodiments of this application, the words "exemplarily" or "for example" are used to indicate examples, illustrations, or explanations. Any embodiment or design described as "exemplarily" or "for example" in the embodiments of this application should not be construed as being more preferred or advantageous than other embodiments or design solutions. Specifically, the use of the words "exemplarily" or "for example" is intended to present the relevant concepts in a specific manner.

[0036] like Figure 1 As shown, Figure 1 This is a schematic diagram of the internal modules of a constant current source according to the present invention. The constant current source consists of five modules: an isolated power supply module, an isolated CAN communication module, a microcontroller control module, a sampling module, and a constant current control module.

[0037] exist Figure 1 In this system, the power supply unit provides power to the isolated power module. The power supply unit can be a bus within a device. When this device contains complex electrical components such as servo motors and electromagnetic pulse generators, the current within the bus (power supply unit) will be interfered with. This interference transforms the originally relatively pure current into a current containing noise such as peak pulse currents. This interfered current will disrupt the output of the existing constant current source, making its output unstable.

[0038] The isolation power supply module in the constant current source electrically isolates the power supply device from other modules within the constant current source. The isolation CAN communication module ensures more stable communication between the constant current source and the host computer. The microcontroller control module receives commands from the host computer and controls the operation of the isolation power supply module and the output of the constant current control module. The constant current control module receives the output of the isolation power supply module and converts it into a preset value specified by the host computer for output. The sampling module acquires the output current of the power conversion module and returns it to the microcontroller control module. The microcontroller control module uses this returned sampled current to adjust the current output of the constant current control module through feedback until it reaches the preset value.

[0039] exist Figure 1 The solid arrow in the image indicates that it transmits analog signals, meaning that the starting module of the arrow supplies power to the ending module of the arrow. Figure 1 The dashed arrows in the diagram represent signal transmission, indicating that the signal is transmitted from the starting module of the arrow to the ending module of the arrow.

[0040] The following sections detail the various modules within the constant current source:

[0041] Isolated power supply module:

[0042] In the constant current source circuit described above, the isolation power supply module is used to separate the power supply device from the subsequent modules. The power supply device contains complex noise, which can affect the normal operation of each module in this constant current source; therefore, the isolation power supply module is used to separate the power supply device from the subsequent modules.

[0043] For example, such as Figure 2 As shown, Figure 2 This is a schematic diagram of an isolated power supply module. The isolated power supply module includes a power conversion module, which converts the voltage output from the power supply device to a stable output voltage. The power conversion module has input terminals (pins 1 and 3), output terminals (pins 4 and 8), and a control terminal (pin 2). The input terminals of the power conversion module are the same as the input terminals of the isolated power supply module, and the output terminals of the power conversion module are the same as the output terminals of the isolated power supply module.

[0044] The input terminal of the power conversion module is connected to the output terminal of the power supply device, the output terminal is connected to the constant current control module, and the control terminal is connected to the microcontroller control module. The microcontroller control module controls the voltage level of the power conversion module's control terminal, thereby controlling the switching between the power conversion module's operating and disconnected states. When the power conversion module is in the operating state, its output terminal converts the input voltage and outputs it. When the power conversion module is in the disconnected state, its output terminal has no voltage output.

[0045] Furthermore, such as Figure 2 As shown, the isolated power supply module also includes an optocoupler controller and a filter module. One end of the optocoupler controller is connected to the control terminal (pin 2) of the power conversion module, and the other end is used by the microcontroller control module. Figure 2 (The SYS-CON pin connects to the microcontroller control module). The optocoupler controller also has an active and inactive state. When the microcontroller control module sends a high-level signal to the optocoupler controller, the controller activates. Specifically, the high-level signal from the microcontroller control module activates the LED in the optocoupler controller, causing it to emit light. The LED then activates the photodetector (such as a phototransistor) in the optocoupler controller, causing it to switch from open to closed. Since the photodetector is connected to the control terminal of the power conversion module, the closing of the photodetector directly causes a change in the potential at the control terminal of the power conversion module.

[0046] exist Figure 2 In this configuration, terminal 3 of the optocoupler controller is connected to ground, and terminal 4 is connected to the control terminal of the power conversion device. A photodetector is located between terminals 3 and 4 of the optocoupler controller. When the power conversion device detects a potential of 0, it enters the operating state. When the photodetector is closed, the control terminal of the power conversion module is directly connected to ground. Figure 2 In the middle, it is connected to the negative terminal MP- of the power supply device's output. Generally, the voltage of the neutral line is 0V, so the potential of the control terminal of the power conversion module is 0V at this time. This potential change will be sensed by the power conversion module (U1), thereby causing the power conversion module to switch from the off state to the working state.

[0047] Furthermore, such as Figure 2 As shown, the optocoupler controller also has a corresponding optocoupler filtering module, which includes capacitors C1 and C6. Capacitor C1 is connected in parallel to the input terminal (i.e., the light-emitting diode) of the optocoupler controller, and capacitor C6 is connected in parallel to the output terminal (i.e., the photodetector) of the optocoupler controller. Capacitor C1 is used to suppress low-frequency ripple, and capacitor C6 is used to filter high-frequency noise. Capacitors C1 and C6 together ensure the stability of the signals transmitted by the microcontroller control module.

[0048] In this technology, a power conversion module isolates the power supply device from the constant current source circuit, preventing noise from the power supply device from affecting the output of the subsequent constant current source. Furthermore, connecting the power conversion module's control terminal to an optocoupler controller isolates the microcontroller control module from the power conversion module. Since the power conversion module is directly connected to the power supply device, and the negative terminal of the power supply device poses a noise risk, the optocoupler controller blocks the voltage input from the power supply device from affecting the microcontroller control module.

[0049] The filtering module includes an input filtering module and an output filtering module. The input filtering module includes capacitors C2, C3, C4, and C5. The output filtering module includes capacitors C7 and C8. Capacitor C2 is connected between the positive terminal (MP+) of the power supply output and ground, and capacitor C3 is connected between the negative terminal (MP-) of the power supply output and ground. Capacitors C2 and C3 remove high-frequency signals from the power supply output and suppress noise. Capacitor C4 has a larger capacitance than capacitor C5, and C4 and C5 are connected in parallel. Similarly, capacitor C7 has a smaller capacitance than capacitor C8, and C7 and C8 are connected in parallel. Furthermore, capacitor C8 is a polarized capacitor, with its positive terminal connected to the positive terminal of the power conversion module output and its negative terminal connected to the negative terminal of the power conversion module output. The combination of capacitors C4 and C5 is similar to the combination of capacitors C7 and C8, both consisting of a large capacitor and a small capacitor connected in parallel. The large capacitor removes high-frequency noise, while the small capacitor removes low-frequency noise. Connecting them in parallel provides dual filtering and covers a wider filtering range.

[0050] Through the design of each circuit in the above-described isolated power supply module, the isolated power supply module can isolate the input while providing a clean voltage output to subsequent circuits. Figure 2 (28V voltage output).

[0051] Isolated CAN communication module:

[0052] The isolated CAN communication module includes an isolated CAN transceiver, decoupling circuitry, and CAN bus protection circuitry.

[0053] 1) Isolated CAN transceiver

[0054] Isolated CAN transceivers are used to enable signal transmission between a microcontroller control module and the CAN bus, while providing isolation. Isolated CAN transceivers enhance the anti-interference capability of isolated CAN communication modules and protect the CAN bus from bus noise, ground loops, or transient voltage interference.

[0055] like Figure 3 As shown, Figure 3 This is a schematic diagram of the internal circuitry of an isolated CAN communication module. The isolated CAN transceiver U3 is connected to the microcontroller control module via pins 4 and 5. CTX and CRX in the diagram represent the transmit pins (PA12-33) and receive pins (PA11-32) of the microcontroller control module. Therefore, the isolated CAN communication module is controlled by the microcontroller control module to communicate with the host computer containing the constant current source circuit, receive control commands from the constant current source circuit, and output signals to the host computer.

[0056] The operation of the isolated CAN communication module will then be explained using a scenario as an example, as follows: In one scenario, the user controls the host computer to issue a control command to activate the constant current source circuit. The host computer then transmits the control command via the CAN bus to the isolated CAN transceiver in the isolated CAN communication module. The isolated CAN transceiver receives the control command and sends it to the microcontroller control module, which then controls the constant current source circuit to operate. At this time, the isolated power supply module switches to the working state, and both the constant current control module and the sampling module are also in working state.

[0057] In addition, during the operation of the constant current source circuit, the circuit generates some operating parameters, such as output current. These operating parameters are collected by the microcontroller control module and sent to the isolated CAN communication module, which then transmits them to the host computer via the CAN bus. The user can then observe the data received by the host computer to obtain the operating status of the constant current source circuit.

[0058] In an isolated CAN communication module, communication can be performed using the CAN protocol or a derivative protocol of the CAN protocol (such as the CAN-FD protocol). No limitation is made here.

[0059] Isolated CAN transceivers achieve signal transmission and electrical isolation between the MCU and the CAN bus through isolation, thereby improving communication reliability and anti-interference capability.

[0060] like Figure 4 As shown, Figure 4 This is a schematic diagram of the internal structure of an isolated CAN transceiver. In some embodiments, the isolated CAN transceiver includes a transformer driver, a rectifier module, a signal isolation module, and a signal conversion module.

[0061] The transformer driver is used to acquire a DC signal and convert the DC signal into a high-frequency signal, which is then input into the primary winding of transformer T1. The secondary winding of the transformer is connected to the rectifier module.

[0062] The rectifier module consists of rectifier diode D1. The secondary winding of transformer T1 receives energy from the primary winding via electromagnetic coupling, and outputs a stable DC voltage after passing through rectifier diode D1. This DC voltage powers the signal isolation module and the signal conversion module. Furthermore, this DC voltage is smoothed by a filter capacitor to form a stable isolated power supply (VISOIN and VISOOUT).

[0063] Signal isolation module: The signal isolation module can achieve signal isolation for data transmission through optocouplers, magnetic couplers, or capacitive coupling. Its main function is to transmit the logic level signals sent by the microcontroller control module to the signal conversion module after isolation, and at the same time, return the received logic level signals to the microcontroller control module through the opposite isolation path.

[0064] Signal Conversion Module: The signal conversion module connects directly to CANH and CANL. It performs mutual conversion between standard CAN differential signals and single-ended logic level signals. Through an internal differential amplifier, it demodulates the differential signals (CAN signals) of the CAN bus into single-ended signals (logic level signals), or modulates single-ended logic signals into differential signals for output to the bus.

[0065] The remaining pins, such as VIO and GND1, are used to connect to the logic level interface of the isolated CAN transceiver. VIO determines the logic level voltage when the signal isolation module communicates with the microcontroller control module. CANH and CANL are responsible for connecting to the external bus and transmitting CAN signals.

[0066] The isolated CAN transceiver achieves complete electrical isolation between the microcontroller control module and the CAN bus through isolated power supply and signal isolation modules, effectively improving anti-interference capability, preventing ground loop interference and electromagnetic interference, while enhancing the reliability and safety of the system, and resisting transient high voltage, surge interference and electrostatic discharge. Ultimately, this technology's constant current source circuit can adapt to complex electromagnetic environments.

[0067] In this embodiment, the isolated power supply module and the isolated CAN communication module work together to isolate the power input from the power supply device and the communication line 9, enabling this constant current source circuit to work stably in a complex electromagnetic environment.

[0068] 2) Decoupling circuit

[0069] The decoupling circuit includes capacitors C11 and C12, with C12 having a larger capacitance than C11. One end of capacitor C11 is connected to the output (3V3) of the first power supply module, and the other end is connected to ground. One end of capacitor C12 is connected to the output (5V) of the second power supply module, and the other end is connected to ground. Both the outputs of the first and second power supply modules are connected to the isolated CAN transceiver. The output of the first power supply module supplies the logic level power to the isolated CAN transceiver and is connected to the VIO pin (pin 7) of the isolated CAN transceiver. The output of the second power supply module supplies the internal isolated power supply to the isolated CAN transceiver and is connected to the VCC pin (pin 8) of the isolated CAN transceiver. Capacitors C11 and C12 are used for decoupling the isolated CAN transceiver.

[0070] 3) CAN bus protection circuit

[0071] The CAN bus protection circuit includes capacitors C13, C14, C15, C16, C17, and C18, a TVS diode D4, and a common-mode inductor L1. The isolation and protection mechanisms of this circuit enhance the CAN bus's anti-interference capability and operational stability. The CAN bus uses differential signal transmission and includes two main signal lines: CANH (high level) and CANL (low level). Noise suppression, signal matching, and circuit protection are achieved through filter capacitors, a common-mode inductor, a terminating resistor, and a transient suppressor (TVS diode).

[0072] Capacitors C13 and C14 are connected across pin 11 (GND2) and pin 19 (VISOIN) of the isolated CAN transceiver. Capacitor C14 is connected in parallel with capacitor C13, and the capacitance of capacitor C13 is greater than that of capacitor C14. Pin 19 (VISOIN) provides the operating voltage input for the subsequent CAN bus, with capacitors C13 and C14 used for filtering.

[0073] The common-mode inductor L1 is used to receive the differential signal transmitted by the isolated CAN transceiver and suppress the common-mode noise. The output of the common-mode inductor L1 is connected to the CAN bus, inputting the noise-suppressed signal into the CAN bus.

[0074] The common-mode inductor L1 has four ports: port 1, port 2, port 3, and port 4. Ports 1 and 2 serve as the output terminals of the common-mode inductor and are connected to the CAN bus. Ports 3 and 4 are connected to pin 15 (CANL) and pin 17 (CANH) of the isolated CAN transceiver, respectively. Pins 15 (CANL) and 17 (CANH) of the isolated CAN transceiver transmit the high and low portions of the differential signal, respectively.

[0075] Furthermore, capacitors C17 and C18 are connected in series, and this series connection is bridged between pins 15 (CANL) and 17 (CANH) of the isolated CAN transceiver. The midpoint of capacitors C17 and C18 is connected to ground. Capacitors C17 and C18 together suppress common-mode noise. Additionally, at the output of common-mode inductor L1, a TVS diode D4 is connected between ports 1 and 2 of common-mode inductor L1. In other words, TVS diode D4 is connected in parallel with the output of common-mode inductor L1. TVS diode D4 can suppress transient spike currents and surge currents, thereby protecting the circuit.

[0076] Furthermore, the CAN bus protection circuit also includes a terminating resistor R6 connected between ports 1 and 2 of the common-mode inductor L1, wherein the resistance of the terminating resistor R6 is greater than 100 ohms. The terminating resistor R6 is used for CAN bus termination matching, thereby avoiding signal reflection and improving signal integrity.

[0077] By employing an isolated CAN transceiver, decoupling circuit, and CAN bus protection circuit, the data transmission of the CAN bus can withstand complex electromagnetic environments. Furthermore, the differential bus method suppresses common-mode interference. The design of the common-mode inductor, filter capacitor, and TVS in the CAN bus protection circuit effectively responds to instantaneous current spikes, clamping the voltage on the CAN bus within a certain range, thus protecting the circuit. Through the design of the above circuit, the isolated CAN communication module can still transmit accurate signals under extremely complex conditions.

[0078] Microcontroller control module:

[0079] The microcontroller control module receives control commands from the host computer via an isolated CAN communication module. These commands instruct the constant current control module to generate current parameters, such as waveform, pulse width, and peak current. The microcontroller control module then controls the constant current control module to output the same current as required by the control commands and sends an ACK signal back to the host computer via the CAN bus. The ACK signal may include parameters such as the operating status and duration of the constant current source.

[0080] like Figure 5 As shown, Figure 5 This is a schematic diagram of a microcontroller control module. Figure 5 It is divided into 4 parts, of which (a) is a schematic diagram of the microprocessor, (b) is a schematic diagram of the reset module, (c) is a schematic diagram of the indicator light module, and (d) is a schematic diagram of the debug interface module.

[0081] The microcontroller control module includes a microprocessor, a reset module, an indicator light module, and a debug interface module. These modules provide system reset, status indication, and debug interface functions, respectively, ensuring stable system operation and convenient debugging.

[0082] like Figure 5 As shown in section (b), the core of the reset module is the reset chip U7, which controls the microprocessor to reset when the power supply voltage is abnormal. Resetting means restoring the microprocessor to its initial state. The input terminal (pin 3) of the reset chip U7 is connected to a 3.3V power supply, which is also the power supply for the microprocessor. The reset chip U7 monitors the voltage of this 3.3V power supply. When the voltage of the 3.3V power supply is lower than a preset voltage threshold (e.g., 1.5V), the reset chip U7 controls the microprocessor to reset. The output terminal (pin 2) of the reset chip U7 is connected to ground through capacitor C27 to form a buffer for the reset signal and prevent the reset signal from being affected by high-frequency interference. In addition, the reset chip U7 also performs reset operations on the microprocessor during power-on and power-off processes.

[0083] The reset module also includes a filter capacitor C28 to eliminate interference noise on the reset signal line and ensure the stability of the reset signal. The design of the reset module ensures that the microcontroller can reliably enter normal operating condition during power-on or system malfunctions.

[0084] like Figure 5 As shown in section (c), the indicator module consists of two LEDs (LED1 and LED2) and their current-limiting resistors (R8 and R9), used to indicate the system's operating status and debugging process. The positive terminals of LED1 and LED2 are connected to the 3.3V power supply through resistors R8 and R9, respectively, while the negative terminals are directly connected to ground (DGND). When the system is working, the control circuit will light up or turn off the corresponding indicator to inform the user of the system's current operating status. For example, LED1 may be used to indicate that the system power supply is normal, and LED2 may be used to indicate whether a specific function is activated. Through this simple and intuitive indication method, users can quickly understand the status of the isolated power supply module, thus facilitating operation and debugging.

[0085] like Figure 5As shown in section (d), the debug interface module includes a set of 4-pin socket J1 and connected voltage divider resistors (R6 and R7) to provide a standard SWD (Servicing Debug) debug interface for the system. The SWDIO and SWCLK pins of socket J1 are connected to the main control chip via resistors R6 and R7, respectively, forming data and clock channels. The debug interface module allows developers to communicate with the main control chip via the SWD interface, upload programs, or debug the system. Socket J1 also provides reference power and ground to the debugging device via pins connected to ground (DGND) and power supply (3.3V). The design of the debug interface module facilitates system debugging, testing, and firmware updates, improving development efficiency.

[0086] Furthermore, in Figure 5 It also includes an external clock consisting of filter capacitors (C25 and C26) and crystal oscillator X1, which provides time indication for the microprocessor's 8-IN and 8-OUT signal interfaces. The external clock allows for more accurate timing of the microprocessor.

[0087] Constant current control module:

[0088] like Figure 6 As shown, Figure 6 This is a circuit diagram of a constant current control module.

[0089] The constant current control module includes: a core constant current module, relay K1, and a relay drive circuit.

[0090] The core constant current module has an input terminal (pins 1 and 3 of U2) and an output terminal (pins 4 and 6 of U2). The input terminal is connected to the output terminal of the isolated power supply module, and the output terminal outputs voltage. A ninth capacitor C9 is connected across the input terminals of the core constant current module to smooth the voltage and suppress high-frequency noise on the input side.

[0091] In addition, the core constant current module also includes a control terminal, which can be divided into a first control terminal and a second control terminal. The microcontroller control module is connected to the first control terminal (pin 6, VSET) of the core constant current module via its pin 14 (DACO). The first control terminal of the core constant current module is used to receive control signals from the microcontroller control module, thereby regulating the voltage output by the core constant current module. The microcontroller control module is connected to the second control terminal (pin 5, ISET) of the core constant current module via its pin 15 (DAC1). The second control terminal is used to receive control signals, thereby regulating the current output by the core constant current module.

[0092] The circuit connecting the microcontroller control module and the core constant current module also includes Zener diodes (D3 and D6) and voltage divider resistors (R5 and R14). The two Zener diodes provide reference voltage protection for DAC0 (voltage setting) and DAC1 (current setting), respectively, preventing damage to the core constant current module due to accidental overvoltage. The two voltage divider resistors are used for voltage setting of DAC0 and DAC1, serving as signal conditioning and voltage dividers to ensure that the voltage input received by the core constant current module is within a reasonable range.

[0093] In addition, the microcontroller control module can also send another control signal, which controls the relay drive circuit and then controls the relay to switch the output of the core constant current module to different circuits.

[0094] The relay drive circuit includes at least one transistor Q1. Transistor Q1 amplifies the control signal from the microcontroller control module, as the current released by the microcontroller control module is insufficient to drive relay K1. When transistor Q1 receives the control signal from the microcontroller control module, it amplifies the drive current and drives relay K1 accordingly. When relay K1 is operating, it connects its pin 5 to different circuits, allowing the constant current control module to discharge to different circuits.

[0095] Furthermore, when relay K1 is driven by a coil, the coil in relay K1 can be considered as an inductor. In this case, the relay driving circuit also includes a freewheeling diode D2. The freewheeling diode D2 is connected in parallel with the control port of relay K1 to absorb the back electromotive force generated by the coil in relay K1, preventing the back electromotive force from damaging the microcontroller control module.

[0096] Sampling module:

[0097] As the constant current control module operates, heat will gradually accumulate. When the accumulated heat reaches a certain level, the constant current control module can no longer output current and voltage with high precision. The sampling module corrects the output of the constant current control module when there is a deviation in the current and voltage output.

[0098] like Figure 7 As shown, Figure 7 This is a schematic diagram of the circuit structure of a sampling module. Figure 7 There are two circuit structure diagrams, namely (a) and (b). The sampling resistor 8 is R14. Part (a) is the voltage sampling circuit. Part (b) measures the voltage output from the constant current control module. Figure 6(a) The sampling circuit samples the current passing through the sampling resistor 8. To minimize the impact on the constant current control module output, the sampling resistor 8 should be as small as possible, for example, a material resistor with a resistance of 20mΩ. Then... Figure 7 The circuits in (a) and (b) are described in detail separately, as follows:

[0099] (a) Voltage sampling circuit:

[0100] The voltage sampling circuit directly measures the voltage VO+ at the output of the constant current control module, and the acquired signal is amplified by the first operational amplifier U11. Figure 7 In part (a), resistors R16 and R17 are used for voltage division, reducing the voltage at the output of the constant current control module. The reduced voltage can then be transmitted to the ADC (analog-to-digital converter) for processing via the ADC1 port. Capacitor C32 is used for filtering.

[0101] (b) Current sampling circuit:

[0102] The current sampling circuit measures the sampling resistor 8 (i.e. Figure 7 The voltage across resistor R14 is used to calculate the current at the output of the constant current control module. Specifically, one end of the sampling resistor 8 is connected to one end of the load, and the other end of the sampling resistor 8 is connected to ground, with the other end of the load connected to the output of the constant current control module. Alternatively, one end of the sampling resistor 8 can be connected to the output of the constant current control module, and the other end can be connected to the load.

[0103] exist Figure 7 In part (b), the differential operational amplifier U12 amplifies the voltage signal of the sampling resistor 8. Gain resistors R15, R18, and R20 form a gain network to amplify the voltage of the sampling resistor 8. The filter capacitor C33 is used to filter out high-frequency noise in the sampling signal. Finally, the current signal acquired by the current sampling circuit is input to the ADC2 pin and transmitted to the corresponding ADC for analog-to-digital conversion.

[0104] The ADC (Analog-to-Digital Converter) acquires the voltage and current signals from the output of the constant current control module and inputs them to the microcontroller control module. This allows the microcontroller control module to obtain the voltage and current values ​​from the constant current control module's output. The microcontroller control module then adjusts the constant current control module based on the voltage and current values ​​transmitted by the ADC. Specifically, the microcontroller control module adjusts the constant current control module's output through feedback.

[0105] In some embodiments, the microcontroller control module directly changes the output of the core constant current module through a first control terminal and / or a second control terminal. As explained above, the first and second control terminals are used to control the output voltage and output current of the core constant current module, respectively. Therefore, a PID algorithm can be used to control the output of the core constant current module until the output of the core constant current module reaches a preset value.

[0106] In other embodiments, the microcontroller control module converts the microcontroller's digital signals into analog signals via a DAC (digital-to-analog converter) and directly inputs the analog signals into the output of the core constant current module, thereby controlling the output of the constant current source so that the output of the constant current source is a preset value.

[0107] Furthermore, this constant current source also includes a chip power supply module, which converts the input voltage into one or more preset voltages. The preset voltages provide voltage to the isolated CAN communication module, the microcontroller control module, the sampling module, and the constant current source control module. The input voltage can be the voltage provided by the output terminal of the power supply device, or it can be the voltage provided by another voltage supply device. That is, the voltage received by the chip power supply module and the voltage received by the isolated power supply module can be the same or different.

[0108] Furthermore, the chip power supply module includes a first power supply module and a second power supply module. The first power supply module converts the input voltage into a first preset voltage, and the second power supply module converts the first preset voltage into a second preset voltage. The first preset voltage is used to provide voltage to the isolated CAN communication module and the constant current source control module, and the second preset voltage is used to provide voltage to the isolated CAN communication module, the microcontroller control module, and the sampling module. The first power supply module acts as an isolation element, isolating the input voltage received by the chip power supply module from the preset voltage output by the chip power supply module.

[0109] like Figure 8a and Figure 8b As shown, Figure 8a This is a structural diagram of the first power supply module. Figure 8b This is a schematic diagram of the second power supply module.

[0110] like Figure 8aAs shown, the first power supply module includes a power conversion chip U3. The input terminals of the power conversion chip U3 are connected to the input voltage received by the chip power supply module. Its input terminals (pins 1 and 2) are connected to a 12V input voltage, and high-frequency noise at the input terminal is suppressed by a filter capacitor. The output terminals (pins 5 and 7) generate a first preset voltage of 5V, which is further supplied to the second power supply module. The internal isolation structure of the power conversion chip U3 ensures electrical isolation between the input and output, providing a stable and clean voltage output for subsequent modules.

[0111] like Figure 8b As shown, the function of the second power supply module is to further convert the 5V voltage in the first preset voltage to a second preset voltage of 3.3V, which is used to power the isolated CAN communication module, the microcontroller control module, and the sampling module. The second power supply module implements this function using a voltage regulator chip (such as the HT7833), whose input is connected to the 5V output of the first power supply module, and whose output generates a stable 3.3V voltage. The voltage regulator chip internally uses a high-precision voltage regulation circuit and an output filtering module to ensure that the output voltage meets the accuracy requirements of low-voltage devices. The second preset voltage directly powers the microcontroller control module, the isolated CAN communication module, and the sampling module, providing excellent power support.

[0112] Through the coordinated operation of the first and second power supply modules, the chip power supply module not only converts the input voltage to multiple preset voltages but also effectively isolates noise at the input end, providing a fundamental guarantee for the stable operation of the constant current source system. In particular, the isolation components in the first power supply module and the voltage regulation design in the second power supply module make the power output cleaner, meeting the power supply needs of different modules.

[0113] like Figure 9 As shown, Figure 9 This is a schematic diagram of a constant current source circuit board.

[0114] The present invention also provides a constant current source circuit board, which includes: a first layer 1, a wiring layer 2, a ground layer 3 and a second layer 4 arranged sequentially from top to bottom; an isolated power supply module, an isolated CAN communication module and a constant current control module are located on the side of the first layer 1 away from the second layer 4; a microcontroller control module and a sampling module are located on the side of the second layer 4 away from the first layer 1; the output terminal of the power supply device is connected in the first layer 1, and the power supply device is used to supply power to the isolated power supply module.

[0115] like Figure 9 As shown, the circuit board comprises a four-layer structure. Wiring layer 2 is used to accommodate internal traces. Ground layer 3 provides grounding for the various components on the circuit board. Figure 9The upper surface of the circuit board (top of layer 1) contains an isolated power supply module, an isolated CAN communication module, and a constant current control module. The lower surface of the circuit board (bottom of layer 4) contains a microcontroller control module and a sampling module. A four-layer structure is used because the microcontroller control module and the sampling module are precision components; even a small amount of interference can significantly affect the output of the entire constant current source circuit.

[0116] The above design concentrates the isolated power supply module, isolated CAN communication module, and constant current control module on the upper surface of the circuit board, and the microcontroller control module and sampling module on the lower surface, maximizing the spatial distance between the devices on these two surfaces. Furthermore, the intermediate ground layer 3 allows high-power and high-noise devices to be concentrated on the upper surface of the circuit board, while ground layer 3 provides protection for the lower surface of the second circuit board, blocking electromagnetic pulses emitted from the devices on the upper surface. This design provides excellent electromagnetic shielding, reduces ground loops and noise interference, and facilitates stable operation of the microcontroller control module and sampling module in complex electromagnetic environments. Additionally, placing the isolated power supply module, isolated CAN communication module, and constant current control module on the upper surface of the circuit board simplifies the heat dissipation design of the constant current source circuit, and allows for centralized placement of heat dissipation devices, resulting in better overall heat dissipation.

[0117] Furthermore, such as Figure 10 As shown, Figure 10 This is a schematic diagram of a ground layer. The ground layer 3 includes a signal ground 5 and a power ground 6, wherein the signal ground 5 and the power ground 6 are separately disposed, and are connected at a single point. Figure 10 In this configuration, a short bridge 7 is used to connect signal ground 5 and power ground 6. The material used in the short bridge 7 is copper.

[0118] Specifically, such as Figures 2 to 8b As shown, all GND ports are connected to power ground 6, and all DGND ports are connected to signal ground 5. Then, power ground 6 and signal ground 5 are connected through a very small copper plate (short bridge 7) to avoid interference between the two grounds.

[0119] Furthermore, the sampling module includes a sampling resistor 8 and a differential operational amplifier, wherein the input terminal wire 11 of the differential operational amplifier is connected to both ends of the sampling resistor 8 and acquires the voltage signal of the sampling resistor 8, and the endpoints of the input terminal wire 11 are respectively located on two solder points 10 of the sampling resistor 8.

[0120] like Figure 11 As shown, Figure 11This is a schematic diagram of a portion of the structure of a sampling module. The sampling resistor 8 is connected to line 9 via solder joint 10. Line 9 is the output circuit of the constant current control module. In the prior art, since line 9 is considered to have zero resistance, the input wire 11 of the differential operational amplifier is connected to line 9. However, in this technology, the input wire 11 is directly connected to solder joint 10 of the sampling resistor 8.

[0121] To reduce the impact of sampling resistor 8 on the output of the constant current control module, the resistance of sampling resistor 8 itself is very low, ranging from a few milliohms to tens of milliohms. In this case, the resistance of line 9 itself could potentially affect the final calculation accuracy. Therefore, directly connecting the input wire 11 to the solder joint 10 of sampling resistor 8 helps to more accurately obtain the current flowing through sampling resistor 8, enabling the microcontroller control module to more precisely control the constant current control module.

[0122] It is understood that, in order to achieve the above functions, the electronic device includes the corresponding hardware structure and / or software module for performing each function. Those skilled in the art will readily recognize that, based on the algorithmic steps of the examples described in conjunction with the embodiments disclosed herein, the present invention can be implemented in hardware or a combination of hardware and computer software. Whether a function is performed in hardware or by computer software driving hardware depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the present invention.

[0123] In this embodiment of the invention, the electronic device can be divided into functional modules according to the above method example. For example, each function can be divided into its own functional module, or two or more functions can be integrated into one processing module. The integrated module can be implemented in hardware or as a software functional module. It should be noted that the module division in this embodiment of the invention is illustrative and only represents one logical functional division; other division methods may be used in actual implementation.

[0124] It is understood that the processor in the embodiments of this application may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, transistor logic devices, hardware components, or any combination thereof. The general-purpose processor may be a microprocessor or any conventional processor.

[0125] The method steps in the embodiments of this application can be implemented in hardware or by a processor executing software instructions. The software instructions can consist of corresponding software modules, which can be stored in random access memory (RAM), flash memory, read-only memory (ROM), programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically erasable programmable read-only memory (EEPROM), registers, hard disks, portable hard disks, CD-ROMs, or any other form of storage medium known in the art. An exemplary storage medium is coupled to the processor, enabling the processor to read information from and write information to the storage medium. Of course, the storage medium can also be a component of the processor. The processor and the storage medium can reside in an ASIC.

[0126] In the above embodiments, implementation can be achieved entirely or partially through software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented entirely or partially as a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted through the computer-readable storage medium. The computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) means. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center that integrates one or more available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., solid-state drive (SSD)).

[0127] It is understood that the various numerical designations used in the embodiments of this application are merely for descriptive convenience and are not intended to limit the scope of the embodiments of this application.

Claims

1. A constant current source, characterized in that, include: A circuit board, the circuit board comprising: a first layer, a wiring layer, a ground layer and a second layer disposed sequentially from top to bottom; The isolated power supply module, the isolated CAN communication module, and the constant current control module are located on the side of the first layer away from the second layer, while the microcontroller control module and the sampling module are located on the side of the second layer away from the first layer. The output terminal of the power supply device is connected in the first layer. This power supply device supplies power to the isolated power module, and the current output by the power supply device contains noise. The isolated power supply module includes a power conversion module and an optocoupler controller. The input terminal of the power conversion module is the input terminal of the isolated power supply module, and the output terminal of the power conversion module is the output terminal of the isolated power supply module. The power conversion module electrically isolates the input terminal and the output terminal of the power conversion module. The input terminal of the power conversion module is connected to the output terminal of the power supply device, the output terminal of the power conversion module is connected to the constant current control module, and the control terminal of the power conversion module is connected to the microcontroller control module through an optocoupler controller so that the microcontroller control module can control the opening and closing of the power conversion module. The isolated CAN communication module includes an isolated CAN transceiver and a CAN bus protection circuit: wherein the isolated CAN transceiver isolates the primary side and the secondary side of the isolated CAN transceiver, the primary side is connected to the microcontroller control module, and the secondary side is connected to the host computer through the CAN bus protection circuit and the CAN bus; The constant current control module is connected to the isolated power supply module and outputs based on a preset value; The sampling module is located at the output of the constant current control module and is used to acquire the current value at the output of the constant current control module. The microcontroller control module adjusts the output of the constant current control module based on the current value through feedback until a preset value is reached. The sampling module includes a sampling resistor and a differential operational amplifier. The input wire of the differential operational amplifier is connected to both ends of the sampling resistor and acquires the voltage signal of the sampling resistor. The endpoints of the input wire are respectively located on two solder points of the sampling resistor. One end of the sampling resistor is connected to the output of the constant current control module, and the other end is connected to the load. One end of the sampling resistor is connected to one end of the first gain resistor. The other end of the first gain resistor is connected to one end of the second gain resistor and the first end of the differential operational amplifier. The other end of the second gain resistor is connected to the second end of the differential operational amplifier. The other end of the sampling resistor is connected to one end of the third gain resistor. The other end of the third gain resistor is connected to the third end of the differential operational amplifier. The second end of the differential operational amplifier serves as the output of the sampling module. The input wire of the differential operational amplifier is a wire extending from one end of the first gain resistor and a wire extending from one end of the third gain resistor.

2. The constant current source according to claim 1, characterized in that, The CAN bus protection circuit includes: a first capacitor, a second capacitor, a third capacitor, a fourth capacitor, a TVS diode, a common-mode inductor, and a terminating resistor. The common-mode inductor includes: port 1, port 2, port 3, and port 4, wherein ports 1 and 2 are connected to the CAN bus as output terminals of the common-mode inductor, and ports 3 and 4 are connected to the output terminal of the isolated CAN transceiver as input terminals of the common-mode inductor. The output terminal of the isolated CAN transceiver outputs a differential signal. The first capacitor and the second capacitor are connected in series, and the first capacitor and the second capacitor connected in series are connected in parallel between the output terminal of the isolated CAN transceiver and the input terminal of the common mode inductor. The midpoint of the first capacitor and the second capacitor is connected to ground. The third capacitor and the fourth capacitor are connected in series, and the series-connected third capacitor and the fourth capacitor are connected in parallel with the output terminal of the common-mode inductor. The midpoint of the third capacitor and the fourth capacitor is connected to ground. The TVS diode is connected in parallel with the output terminal of the common-mode inductor, and the terminating resistor is connected in parallel with the output terminal of the common-mode inductor.

3. The constant current source according to claim 2, characterized in that, The constant current control module includes: a core constant current module, a relay, and a relay drive circuit. The relay is connected to the output terminal of the core constant current module. When the relay is in different positions, it connects the output terminal of the core constant current module to different circuits. The core constant current module further includes a first control terminal and a second control terminal. The first control terminal is used to receive a voltage control signal from the microcontroller control module, and the second control terminal is used to receive a current control signal from the microcontroller control module. The voltage control signal and the current control signal are used to control the output current and output current of the core constant current module, respectively. The relay driving circuit is used to receive control signals from the microcontroller control module to drive the relay to switch gears. The relay driving circuit also includes a freewheeling diode connected in parallel with the relay coil side.

4. The constant current source according to any one of claims 1-3, characterized in that, The isolated power supply module further includes a first power supply module and a second power supply module. The first power supply module converts the input voltage into a first preset voltage, and the second power supply module converts the first preset voltage into a second preset voltage. The first preset voltage is used to provide voltage to the isolated CAN communication module and the constant current source control module, and the second preset voltage is used to provide voltage to the isolated CAN communication module, the microcontroller control module, and the sampling module. The first power supply module is an isolation element that isolates the input voltage received by the first power supply module from the preset voltages output by the first power supply module and the second power supply module.

5. The constant current source according to claim 4, characterized in that, The isolated CAN communication module further includes a fifth capacitor and a sixth capacitor, wherein the capacitance value of the sixth capacitor is greater than that of the fifth capacitor; wherein one end of the fifth capacitor is connected to the output terminal of the first power supply module and the other end is connected to ground; one end of the sixth capacitor is connected to the output terminal of the second power supply module and the other end is connected to ground.

6. The constant current source according to claim 4 or 5, characterized in that, The microcontroller control module adjusts the output of the constant current control module based on the current value via feedback until a preset value is reached, including: The microcontroller control module obtains the voltage value at the output terminal of the constant current control module, and adjusts the output of the constant current control module until the preset value is reached based on the current value and the voltage value.

7. The constant current source according to claim 1, characterized in that, The isolated CAN transceiver includes a transformer driver, a rectifier module, a signal isolation module, and a signal conversion module; wherein, The transformer driver acquires a DC signal and converts the DC signal into a high-frequency signal, which is then input into the primary winding of the transformer. The secondary winding of the transformer is connected to the rectifier module. The rectifier module obtains the output voltage of the secondary winding of the transformer and outputs a DC voltage, wherein the DC voltage is used to power the signal isolation module and the signal conversion module. One end of the signal isolation module serves as the primary side of the isolated CAN transceiver and is connected to the microcontroller control module. The other end is connected to the first end of the signal conversion module. The second end of the signal conversion module serves as the secondary side of the isolated CAN transceiver. The signal isolation module is used to electrically convert the transmitted and received signals. The signal conversion module converts the CAN signals on the CAN bus into logic level signals, wherein the logic level signals are signals that the microcontroller control module can directly understand.

8. The constant current source according to claim 1, characterized in that, The ground plane includes a signal ground and a power ground, wherein the signal ground and the power ground are separately disposed and connected at a single point.

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