A circuit for detecting a BLDC
By designing a system that includes multiple circuits, the problems of large size, high cost, and limited functionality of traditional FCT systems are solved. This enables diversified testing and real-time display of BLDC motors, reduces costs, and enhances the adaptability of testing functions.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- GUANGDONG ZHAOLI ELECTRIC GROUP CO LTD
- Filing Date
- 2025-07-24
- Publication Date
- 2026-07-24
AI Technical Summary
Traditional FCT systems are bulky, expensive to purchase and maintain, and have limited functionality, making them difficult to adapt to the rapid iteration and ever-changing testing needs of modern electronic products.
A circuit system was designed, including a DC voltage input interface circuit, a test load access interface circuit, a bus voltage detection circuit, a DC-DC BUCK step-down circuit, an overcurrent detection circuit, a main control MCU, an OLED display circuit, an LED status indicator circuit, a buzzer fault alarm circuit, a PWM button circuit, a frequency speed control button circuit, an optocoupler isolation circuit, and a speed control resistor. This system achieves reduced equipment size and diversified testing functions.
It enables BLDC motor speed regulation and real-time display of current, voltage, power, and speed, and has functions for motor electrical performance testing, start-up testing, and forward and reverse rotation testing, which significantly reduces hardware investment and operating costs and enhances the diversity of testing functions.
Smart Images
Figure CN224553439U_ABST
Abstract
Description
Technical Field
[0001] This utility model belongs to the field of detection circuit technology, specifically relating to a circuit for detecting BLDC. Background Technology
[0002] In the electronics manufacturing industry, traditional FCT (Functional Testing) systems generally suffer from large size, high purchase and maintenance costs, and often have limited and fixed testing functions with poor scalability (typically only able to perform specific, fixed test items), making them difficult to adapt to the rapid iteration and ever-changing testing needs of modern electronic products. This system, however, achieves a significant reduction in device size through innovative architecture design, substantially lowering hardware investment and operating costs, while possessing highly flexible and diverse testing capabilities to cover a wider range of testing scenarios and product requirements. Summary of the Invention
[0003] This invention provides a circuit for detecting BLDC. Traditional FCT (Functional Testing) systems generally suffer from large size and high purchase and upgrade costs.
[0004] This utility model is achieved through the following technical solution: A circuit for detecting BLDC, the circuit includes a DC voltage input interface circuit, a test load access interface circuit, a bus voltage detection circuit, a DC-DC BUCK step-down circuit, an overcurrent detection circuit, a main control MCU, an OLED display circuit, an LED status indicator circuit, a buzzer fault alarm circuit, a PWM button circuit, a frequency speed control button circuit, an optocoupler isolation circuit, and a speed control resistor; The main control MCU receives signals from the optocoupler isolation circuit, PWM button circuit, frequency speed control button circuit, overcurrent detection circuit, bus voltage detection, and DC-DC BUCK step-down circuit. The main control MCU sends control signals to the OLED display circuit, the LED status indicator circuit, and the buzzer fault alarm circuit. The overcurrent detection circuit receives the signal from the test load access interface circuit; The DC voltage input interface circuit sends signals to the test load access circuit, bus voltage detection, and DC-DCBUCK step-down circuit.
[0005] Furthermore, the main control MCU includes a chip U2, and terminal 1 of the chip U2 is connected to one end of resistor R13 in the OLED display circuit; Terminal 2 of chip U2 is connected to one end of resistor R17, and the other end of resistor R17 is connected to terminal 3 of chip U2 and one end of capacitor C6, with the other end of capacitor C6 grounded. Terminal 3 of the chip U2 is connected to one end of resistor R14 in the OLED display circuit. Terminal 5 of the chip U2 is connected to one end of resistor R15 in the OLED display circuit. Terminal 6 of the chip U2 is connected to one end of resistor R16 in the OLED display circuit. Terminal 7 of the chip U2 is connected to one end of resistor R38 in the test load access interface circuit. Terminal 8 of the chip U2 is connected to one end of capacitor C6 in the buzzer fault alarm circuit. The 9th terminal of the chip U2 is connected to one end of the resistor R10 and one end of the capacitor C10 of the PWM button circuit, respectively. Terminal 10 of the chip U2 is connected to one end of resistor R35 and one end of capacitor C14 of the frequency speed control button circuit, respectively. Terminal 11 of the chip U2 is connected to one end of resistor R4 and one end of capacitor C5 of the test load access interface circuit, respectively. Terminal 12 of the chip U2 is connected to one end of resistor R5 and the other end of capacitor C5 of the test load access interface circuit. Terminal 13 of the chip U2 is connected to one end of resistor R27 in the optocoupler isolation circuit; Terminal 14 of the chip U2 is connected to one end of resistor R8 in the LED status indicator circuit. Terminal 15 of the chip U2 is connected to one end of resistor R9 in the LED status indicator circuit; Terminal 16 of the chip U2 is connected to terminal 3 of the programming port circuit; Terminal 17 of the chip U2 is connected to terminal 4 of the programming port circuit; Terminal 18 of the chip U2 is connected to one end of the speed control resistor R34 and one end of the capacitor C16, respectively. Terminal 19 of the chip U2 is connected to one end of capacitor C7, one end of capacitor C8, and the ground terminal, respectively. Terminal 20 of the chip U2 is connected to the other end of capacitor C7, the other end of capacitor C8, and the operating voltage +5V, respectively. Terminal 21 of the chip U2 is connected to one end of capacitor C13, one end of resistor R18, and one end of resistor R19, respectively. Terminal 22 of the chip U2 is connected to one end of resistor R22 in the optocoupler isolation circuit; Terminal 24 of the chip U2 is connected to one end of resistor R12 in the OLED display circuit.
[0006] Furthermore, the bus voltage detection includes connecting the other end of capacitor C13 to the other end of resistor R19 and then grounding it, and connecting the other end of resistor R18 to the operating voltage VCC. The DC voltage input interface circuit includes a socket CN1. Terminal 2 of the socket CN1 is connected to the positive terminal of diode D4. The negative terminal of diode D4 is connected to the positive terminal of capacitor CAP1 and one end of capacitor C1, and then connected to the working voltage VCC. Terminal 1 of the connector CN1 is connected to the negative terminal of capacitor CAP1 and the other end of capacitor C1, and then grounded.
[0007] Furthermore, the optocoupler isolation circuit includes a PWM isolation output circuit and an FG isolation input circuit; The other end of resistor R22 in the PWM isolation output circuit is connected to terminal 2 of optocoupler GE1 and one end of resistor R23, respectively, and the other end of resistor R23 is grounded. The first terminal of the optocoupler GE1 is connected to the working voltage +5V via a series resistor R7, and the fourth terminal of the optocoupler GE1 is connected to the working voltage +5V via a series resistor R20. The third terminal of the optocoupler GE1 is connected to one end of resistor R24 and one end of resistor R21 respectively; the other end of resistor R24 is grounded, and the other end of resistor R21 is connected to the third terminal of the test load access interface circuit J2. The other end of resistor R27 in the FG isolation input circuit is connected to terminal 3 of optocoupler GE2 and one end of resistor R29, respectively, and the other end of resistor R29 is grounded. The 4th terminal of the optocoupler GE2 is connected to the working voltage +5V after series resistor R25, and the 1st terminal of the optocoupler GE2 is connected to the working voltage +5V after series resistor R26. Terminal 2 of the optocoupler GE2 is connected to one end of resistor R28 and one end of resistor R30, respectively; the other end of resistor R30 is grounded, and the other end of resistor R24 is connected to terminal 4 of the test load access interface circuit J2.
[0008] Furthermore, terminal 6 of interface J2 of the test load access interface circuit is grounded; terminal 5 of interface J2 is connected to the operating voltage +5V. Terminal 1 of interface J2 is connected to terminal D of field-effect transistor Q1. Terminal G of field-effect transistor Q1 is connected to one end of resistor R39 and one end of resistor R31. The other end of resistor R31 is connected to terminal S of field-effect transistor Q1 and ground. Terminal 2 of interface J2 is connected to one end of resistor R3 and the other end of resistor R5 respectively; the other end of resistor R3 is connected to the other end of resistor R4 and the ground terminal respectively. The other end of resistor R39 is connected to terminal 2 of transistor Q1. Terminal 1 of transistor Q1 is connected to one end of resistor R37, the other end of resistor R38, and one end of capacitor C15. The other end of resistor R37 is connected to the other end of capacitor C15, terminal 3 of transistor Q1, and ground.
[0009] Furthermore, the DC-DC BUCK step-down circuit includes a chip U1. Terminal 5 of the chip U1 is connected to the power supply VCC, the positive terminal of capacitor EC2, one end of capacitor C4, and one end of resistor R2. The other end of resistor R2 is connected to terminal 4 of the chip U1. Terminal 6 of the chip U1 is connected to one end of capacitor C2 and one end of inductor L1. The other end of inductor L1 is connected to one end of resistor R1, the positive terminal of capacitor EC1, one end of capacitor C4, and the 5V operating power supply. The negative terminal of capacitor EC2 is connected to the other end of capacitor C4, terminal 2 of chip U1, one end of capacitor C3, the negative terminal of capacitor EC1, and one end of resistor R6, and then grounded. Terminal 3 of the chip U1 is connected to the other end of resistor R6 and the other end of resistor R5, respectively.
[0010] Furthermore, the OLED display circuit includes a chip U3, with terminal 1 of the chip U3 connected to one end of capacitor C12, one end of capacitor C11, and ground, and terminal 2 of the chip U3 connected to the other end of capacitor C12, the other end of capacitor C11, and the operating voltage +5V. Terminal 3 of the chip U3 is connected to the other end of resistor R12; Terminal 4 of the chip U3 is connected to the other end of resistor R13; Terminal 5 of the chip U3 is connected to the other end of resistor R14; Terminal 6 of the chip U3 is connected to the other end of resistor R15; Terminal 7 of the chip U3 is connected to the other end of resistor R16.
[0011] Furthermore, the other end of resistor R8 of the LED status indicator is connected to the positive terminal of LED1, the other end of resistor R9 is connected to the positive terminal of LED2, and the negative terminal of LED1 is connected to the negative terminal of LED2 and then grounded. The other end of capacitor C9 in the buzzer fault alarm circuit is connected to terminal 2 of buzzer BZ1 and the negative terminal of diode D2, respectively. The positive terminal of diode D2 is connected to terminal 1 of buzzer BZ1 and then grounded.
[0012] Furthermore, the other end of the adjustable resistor R34 is connected to the adjustment terminal of the variable resistor R32, one end of the variable resistor R32 is connected to the working voltage +5V, and the other end of the capacitor C16 is connected to the other end of the variable resistor R32 and then grounded.
[0013] The beneficial effects of this utility model are: This invention features BLDC motor speed regulation and real-time display of current, voltage, power, and speed; motor electrical performance testing; BLDC motor start-up testing; and BLDC motor forward and reverse rotation testing. Compared to traditional FCT testing systems, which are large, costly, and have limited testing functions, this system is small, low-cost, and offers diverse testing capabilities. Attached Figure Description
[0014] Figure 1 The structural block diagram of this utility model.
[0015] Figure 2 The main control MCU circuit diagram of this utility model.
[0016] Figure 3 The present invention provides a DC-DC BUCK step-down circuit diagram.
[0017] Figure 4 The circuit diagram of the DC voltage input interface of this utility model.
[0018] Figure 5 The circuit diagram of the test load access interface of this utility model.
[0019] Figure 6 The circuit diagram of the programming port of this utility model.
[0020] Figure 7 The optical coupler isolation circuit diagram of this utility model.
[0021] Figure 8 The circuit diagram of the LED status indicator of this utility model.
[0022] Figure 9 The present invention relates to a buzzer fault alarm circuit diagram.
[0023] Figure 10 The circuit diagram of the speed regulating resistor of this utility model.
[0024] Figure 11 The OLED display circuit diagram of this utility model.
[0025] Figure 12 The present invention provides a bus voltage detection diagram.
[0026] Figure 13 The present invention relates to a PWM button circuit and a frequency speed control button circuit diagram. Detailed Implementation
[0027] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of this application. However, those skilled in the art will understand that this application may also be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods are omitted so as not to obscure the description of this application with unnecessary detail.
[0028] It should be understood that, when used in this specification and the appended claims, the term "comprising" indicates the presence of the described features, integrals, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.
[0029] It should also be understood that the terminology used in this application specification is for the purpose of describing particular embodiments only and is not intended to limit the application. As used in this application specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.
[0030] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.
[0031] Many specific details are set forth in the following description in order to provide a full understanding of this application. However, this application may also be implemented in other ways different from those described herein. Those skilled in the art can make similar extensions without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.
[0032] This embodiment provides a circuit for detecting BLDC, the circuit including a DC voltage input interface circuit, a test load access interface circuit, a bus voltage detection circuit, a DC-DC BUCK step-down circuit, an overcurrent detection circuit, a main control MCU, an OLED display circuit, an LED status indicator circuit, a buzzer fault alarm circuit, a PWM button circuit, a frequency speed control button circuit, an optocoupler isolation circuit, and a speed control resistor; The main control MCU receives signals from the optocoupler isolation circuit, PWM button circuit, frequency speed control button circuit, overcurrent detection circuit, bus voltage detection, and DC-DC BUCK step-down circuit. The main control MCU sends control signals to the OLED display circuit, the LED status indicator circuit, and the buzzer fault alarm circuit. The overcurrent detection circuit receives the signal from the test load access interface circuit; The DC voltage input interface circuit sends signals to the test load access circuit, bus voltage detection, and DC-DCBUCK step-down circuit.
[0033] Furthermore, the main control MCU includes a chip U2, the chip U2 model is RDI32F093M6S8, and terminal 1 of the chip U2 is connected to one end of resistor R13 of the OLED display circuit; Terminal 2 of chip U2 is connected to one end of resistor R17, and the other end of resistor R17 is connected to terminal 3 of chip U2 and one end of capacitor C6, with the other end of capacitor C6 grounded. Terminal 3 of the chip U2 is connected to one end of resistor R14 in the OLED display circuit. Terminal 5 of the chip U2 is connected to one end of resistor R15 in the OLED display circuit. Terminal 6 of the chip U2 is connected to one end of resistor R16 in the OLED display circuit. Terminal 7 of the chip U2 is connected to one end of resistor R38 in the test load access interface circuit. Terminal 8 of the chip U2 is connected to one end of capacitor C6 in the buzzer fault alarm circuit. The 9th terminal of the chip U2 is connected to one end of the resistor R10 and one end of the capacitor C10 of the PWM button circuit, respectively. Terminal 10 of the chip U2 is connected to one end of resistor R35 and one end of capacitor C14 of the frequency speed control button circuit, respectively. Terminal 11 of the chip U2 is connected to one end of resistor R4 and one end of capacitor C5 of the test load access interface circuit, respectively. Terminal 12 of the chip U2 is connected to one end of resistor R5 and the other end of capacitor C5 of the test load access interface circuit. Terminal 13 of the chip U2 is connected to one end of resistor R27 in the optocoupler isolation circuit; Terminal 14 of the chip U2 is connected to one end of resistor R8 in the LED status indicator circuit. Terminal 15 of the chip U2 is connected to one end of resistor R9 in the LED status indicator circuit; Terminal 16 of the chip U2 is connected to terminal 3 of the programming port circuit; Terminal 17 of the chip U2 is connected to terminal 4 of the programming port circuit; Terminal 18 of the chip U2 is connected to one end of the speed control resistor R34 and one end of the capacitor C16, respectively. Terminal 19 of the chip U2 is connected to one end of capacitor C7, one end of capacitor C8, and the ground terminal, respectively. Terminal 20 of the chip U2 is connected to the other end of capacitor C7, the other end of capacitor C8, and the operating voltage +5V, respectively. Terminal 21 of the chip U2 is connected to one end of capacitor C13, one end of resistor R18, and one end of resistor R19, respectively. Terminal 22 of the chip U2 is connected to one end of resistor R22 in the optocoupler isolation circuit; Terminal 24 of the chip U2 is connected to one end of resistor R12 in the OLED display circuit.
[0034] Furthermore, the bus voltage detection includes connecting the other end of capacitor C13 to the other end of resistor R19 and then grounding it, and connecting the other end of resistor R18 to the operating voltage VCC. The DC voltage input interface circuit includes a socket CN1. Terminal 2 of the socket CN1 is connected to the positive terminal of diode D4. The negative terminal of diode D4 is connected to the positive terminal of capacitor CAP1 and one end of capacitor C1, and then connected to the working voltage VCC. Terminal 1 of the connector CN1 is connected to the negative terminal of capacitor CAP1 and the other end of capacitor C1, and then grounded.
[0035] Furthermore, the optocoupler isolation circuit includes a PWM isolation output circuit and an FG isolation input circuit; The other end of resistor R22 in the PWM isolation output circuit is connected to terminal 2 of optocoupler GE1 and one end of resistor R23, respectively, and the other end of resistor R23 is grounded. The first terminal of the optocoupler GE1 is connected to the working voltage +5V via a series resistor R7, and the fourth terminal of the optocoupler GE1 is connected to the working voltage +5V via a series resistor R20. The third terminal of the optocoupler GE1 is connected to one end of resistor R24 and one end of resistor R21 respectively; the other end of resistor R24 is grounded, and the other end of resistor R21 is connected to the third terminal of the test load access interface circuit J2. The other end of resistor R27 in the FG isolation input circuit is connected to terminal 3 of optocoupler GE2 and one end of resistor R29, respectively, and the other end of resistor R29 is grounded. The 4th terminal of the optocoupler GE2 is connected to the working voltage +5V after series resistor R25, and the 1st terminal of the optocoupler GE2 is connected to the working voltage +5V after series resistor R26. Terminal 2 of the optocoupler GE2 is connected to one end of resistor R28 and one end of resistor R30, respectively; the other end of resistor R30 is grounded, and the other end of resistor R24 is connected to terminal 4 of the test load access interface circuit J2.
[0036] Furthermore, terminal 6 of interface J2 of the test load access interface circuit is grounded; terminal 5 of interface J2 is connected to the operating voltage +5V. Terminal 1 of interface J2 is connected to terminal D of field-effect transistor Q1. Terminal G of field-effect transistor Q1 is connected to one end of resistor R39 and one end of resistor R31. The other end of resistor R31 is connected to terminal S of field-effect transistor Q1 and ground. Terminal 2 of interface J2 is connected to one end of resistor R3 and the other end of resistor R5 respectively; the other end of resistor R3 is connected to the other end of resistor R4 and the ground terminal respectively. The other end of resistor R39 is connected to terminal 2 of transistor Q1. Terminal 1 of transistor Q1 is connected to one end of resistor R37, the other end of resistor R38, and one end of capacitor C15. The other end of resistor R37 is connected to the other end of capacitor C15, terminal 3 of transistor Q1, and ground.
[0037] Furthermore, the DC-DC BUCK step-down circuit includes a chip U1, model number BL9641. Terminal 5 of the chip U1 is connected to the power supply VCC, the positive terminal of capacitor EC2, one end of capacitor C4, and one end of resistor R2. The other end of resistor R2 is connected to terminal 4 of the chip U1. Terminal 6 of the chip U1 is connected to one end of capacitor C2 and one end of inductor L1. The other end of inductor L1 is connected to one end of resistor R1, the positive terminal of capacitor EC1, one end of capacitor C4, and the 5V operating power supply. The negative terminal of capacitor EC2 is connected to the other end of capacitor C4, terminal 2 of chip U1, one end of capacitor C3, the negative terminal of capacitor EC1, and one end of resistor R6, and then grounded. Terminal 3 of the chip U1 is connected to the other end of resistor R6 and the other end of resistor R5, respectively.
[0038] Furthermore, the OLED display circuit includes a chip U3, which is an OLED display module. Terminal 1 of the chip U3 is connected to one end of capacitor C12, one end of capacitor C11, and the ground terminal, respectively. Terminal 2 of the chip U3 is connected to the other end of capacitor C12, the other end of capacitor C11, and the operating voltage +5V, respectively. Terminal 3 of the chip U3 is connected to the other end of resistor R12; Terminal 4 of the chip U3 is connected to the other end of resistor R13; Terminal 5 of the chip U3 is connected to the other end of resistor R14; Terminal 6 of the chip U3 is connected to the other end of resistor R15; Terminal 7 of the chip U3 is connected to the other end of resistor R16.
[0039] Furthermore, the other end of resistor R8 of the LED status indicator is connected to the positive terminal of LED1, the other end of resistor R9 is connected to the positive terminal of LED2, and the negative terminal of LED1 is connected to the negative terminal of LED2 and then grounded. The other end of capacitor C9 in the buzzer fault alarm circuit is connected to terminal 2 of buzzer BZ1 and the negative terminal of diode D2, respectively. The positive terminal of diode D2 is connected to terminal 1 of buzzer BZ1 and then grounded.
[0040] Furthermore, the other end of the adjustable resistor R34 is connected to the adjustment terminal of the variable resistor R32, one end of the variable resistor R32 is connected to the working voltage +5V, and the other end of the capacitor C16 is connected to the other end of the variable resistor R32 and then grounded.
[0041] The overcurrent protection circuit consists of resistors R3, R4, R5, and capacitor C5. OPA1_IN and OPA1_IP are connected to the operational amplifier inside the MCU. The amplified voltage is compared with a set voltage by a comparator inside the MCU. If the voltage exceeds the set voltage, an overcurrent occurs, and the output is shut off via MOSFET Q1. This circuit not only has overcurrent detection functionality but also BLDC motor current detection functionality. The voltage from the operational amplifier is transmitted to the MCU's ADC for calculation to obtain the current.
[0042] The circuit works as follows: This invention controls the speed of a BLDC motor using a PWM signal, obtains the real-time speed of the BLDC motor via an FG signal, and obtains the BLDC current through a current detection circuit. By checking whether the BLDC speed and current meet the set values, if they do, the BLDC motor FCT test is successful, with LED1 lighting up green and the OLED display showing "OK". If they do not meet the set values, the BLDC motor FCT test fails, LED2 lights up red, the OLED displays "NG", and a buzzer sounds an alarm. This system can also output PWM and CLK signals via SW1 and SW2, and adjust the duty cycle of the PWM signal or the frequency of the CLK signal using the sliding resistor R32. The BLDC motor speed and current are displayed in real-time on the OLED.
Claims
1. A circuit for detecting BLDC, characterized in that, The circuit includes a DC voltage input interface circuit, a test load access interface circuit, a bus voltage detection circuit, a DC-DC BUCK step-down circuit, an overcurrent detection circuit, a main control MCU, an OLED display circuit, an LED status indicator circuit, a buzzer fault alarm circuit, a PWM button circuit, a frequency speed control button circuit, an optocoupler isolation circuit, and a speed control resistor. The main control MCU receives signals from the optocoupler isolation circuit, PWM button circuit, frequency speed control button circuit, overcurrent detection circuit, bus voltage detection, and DC-DC BUCK step-down circuit. The main control MCU sends control signals to the OLED display circuit, the LED status indicator circuit, and the buzzer fault alarm circuit. The overcurrent detection circuit receives the signal from the test load access interface circuit; The DC voltage input interface circuit sends signals to the test load access circuit, bus voltage detection, and DC-DC BUCK step-down circuit.
2. The circuit according to claim 1, characterized in that, The main control MCU includes a chip U2, and terminal 1 of the chip U2 is connected to one end of resistor R13 in the OLED display circuit; Terminal 2 of chip U2 is connected to one end of resistor R17, and the other end of resistor R17 is connected to terminal 3 of chip U2 and one end of capacitor C6, with the other end of capacitor C6 grounded. Terminal 3 of the chip U2 is connected to one end of resistor R14 in the OLED display circuit. Terminal 5 of the chip U2 is connected to one end of resistor R15 in the OLED display circuit. Terminal 6 of the chip U2 is connected to one end of resistor R16 in the OLED display circuit. Terminal 7 of the chip U2 is connected to one end of resistor R38 in the test load access interface circuit. Terminal 8 of the chip U2 is connected to one end of capacitor C6 in the buzzer fault alarm circuit. The 9th terminal of the chip U2 is connected to one end of the resistor R10 and one end of the capacitor C10 of the PWM button circuit, respectively. Terminal 10 of the chip U2 is connected to one end of resistor R35 and one end of capacitor C14 of the frequency speed control button circuit, respectively. Terminal 11 of the chip U2 is connected to one end of resistor R4 and one end of capacitor C5 of the test load access interface circuit, respectively. Terminal 12 of the chip U2 is connected to one end of resistor R5 and the other end of capacitor C5 of the test load access interface circuit. Terminal 13 of the chip U2 is connected to one end of resistor R27 in the optocoupler isolation circuit; Terminal 14 of the chip U2 is connected to one end of resistor R8 in the LED status indicator circuit. Terminal 15 of the chip U2 is connected to one end of resistor R9 in the LED status indicator circuit; Terminal 16 of the chip U2 is connected to terminal 3 of the programming port circuit; Terminal 17 of the chip U2 is connected to terminal 4 of the programming port circuit; Terminal 18 of the chip U2 is connected to one end of the speed control resistor R34 and one end of the capacitor C16, respectively. Terminal 19 of the chip U2 is connected to one end of capacitor C7, one end of capacitor C8, and the ground terminal, respectively. Terminal 20 of the chip U2 is connected to the other end of capacitor C7, the other end of capacitor C8, and the operating voltage +5V, respectively. Terminal 21 of the chip U2 is connected to one end of capacitor C13, one end of resistor R18, and one end of resistor R19, respectively. Terminal 22 of the chip U2 is connected to one end of resistor R22 in the optocoupler isolation circuit; Terminal 24 of the chip U2 is connected to one end of resistor R12 in the OLED display circuit.
3. The circuit according to claim 2, characterized in that, The bus voltage detection includes connecting the other end of capacitor C13 to the other end of resistor R19 and then grounding it, and connecting the other end of resistor R18 to the working voltage VCC. The DC voltage input interface circuit includes a socket CN1. Terminal 2 of the socket CN1 is connected to the positive terminal of diode D4. The negative terminal of diode D4 is connected to the positive terminal of capacitor CAP1 and one end of capacitor C1, and then connected to the working voltage VCC. Terminal 1 of the connector CN1 is connected to the negative terminal of capacitor CAP1 and the other end of capacitor C1, and then grounded.
4. The circuit according to claim 2, characterized in that, The optocoupler isolation circuit includes a PWM isolation output circuit and an FG isolation input circuit; The other end of resistor R22 in the PWM isolation output circuit is connected to terminal 2 of optocoupler GE1 and one end of resistor R23, respectively, and the other end of resistor R23 is grounded. The first terminal of the optocoupler GE1 is connected to the working voltage +5V via a series resistor R7, and the fourth terminal of the optocoupler GE1 is connected to the working voltage +5V via a series resistor R20. The third terminal of the optocoupler GE1 is connected to one end of resistor R24 and one end of resistor R21 respectively; the other end of resistor R24 is grounded, and the other end of resistor R21 is connected to the third terminal of the test load access interface circuit J2. The other end of resistor R27 in the FG isolation input circuit is connected to terminal 3 of optocoupler GE2 and one end of resistor R29, respectively, and the other end of resistor R29 is grounded. The 4th terminal of the optocoupler GE2 is connected to the working voltage +5V after series resistor R25, and the 1st terminal of the optocoupler GE2 is connected to the working voltage +5V after series resistor R26. Terminal 2 of the optocoupler GE2 is connected to one end of resistor R28 and one end of resistor R30, respectively; the other end of resistor R30 is grounded, and the other end of resistor R24 is connected to terminal 4 of the test load access interface circuit J2.
5. The circuit according to claim 4, characterized in that, The 6th terminal of interface J2 of the test load access interface circuit is grounded; the 5th terminal of interface J2 is connected to the operating voltage +5V. Terminal 1 of interface J2 is connected to terminal D of field-effect transistor Q1. Terminal G of field-effect transistor Q1 is connected to one end of resistor R39 and one end of resistor R31. The other end of resistor R31 is connected to terminal S of field-effect transistor Q1 and ground. Terminal 2 of interface J2 is connected to one end of resistor R3 and the other end of resistor R5 respectively; the other end of resistor R3 is connected to the other end of resistor R4 and the ground terminal respectively. The other end of resistor R39 is connected to terminal 2 of transistor Q1. Terminal 1 of transistor Q1 is connected to one end of resistor R37, the other end of resistor R38, and one end of capacitor C15. The other end of resistor R37 is connected to the other end of capacitor C15, terminal 3 of transistor Q1, and ground.
6. The circuit according to claim 2, characterized in that, The DC-DC BUCK step-down circuit includes a chip U1. Terminal 5 of the chip U1 is connected to the power supply VCC, the positive terminal of capacitor EC2, one end of capacitor C4, and one end of resistor R2. The other end of resistor R2 is connected to terminal 4 of the chip U1. Terminal 6 of the chip U1 is connected to one end of capacitor C2 and one end of inductor L1. The other end of inductor L1 is connected to one end of resistor R1, the positive terminal of capacitor EC1, one end of capacitor C4, and the 5V operating power supply. The negative terminal of capacitor EC2 is connected to the other end of capacitor C4, terminal 2 of chip U1, one end of capacitor C3, the negative terminal of capacitor EC1, and one end of resistor R6, and then grounded. Terminal 3 of the chip U1 is connected to the other end of resistor R6 and the other end of resistor R5, respectively.
7. The circuit according to claim 2, characterized in that, The OLED display circuit includes a chip U3. Terminal 1 of the chip U3 is connected to one end of capacitor C12, one end of capacitor C11, and ground. Terminal 2 of the chip U3 is connected to the other end of capacitor C12, the other end of capacitor C11, and the operating voltage +5V. Terminal 3 of the chip U3 is connected to the other end of resistor R12; Terminal 4 of the chip U3 is connected to the other end of resistor R13; Terminal 5 of the chip U3 is connected to the other end of resistor R14; Terminal 6 of the chip U3 is connected to the other end of resistor R15; Terminal 7 of the chip U3 is connected to the other end of resistor R16.
8. The circuit according to claim 2, characterized in that, The other end of resistor R8 of the LED status indicator is connected to the positive terminal of LED1, the other end of resistor R9 is connected to the positive terminal of LED2, and the negative terminal of LED1 is connected to the negative terminal of LED2 and then grounded. The other end of capacitor C9 in the buzzer fault alarm circuit is connected to terminal 2 of buzzer BZ1 and the negative terminal of diode D2, respectively. The positive terminal of diode D2 is connected to terminal 1 of buzzer BZ1 and then grounded.
9. The circuit according to claim 2, characterized in that, The other end of the adjustable resistor R34 is connected to the adjustment terminal of the variable resistor R32. One end of the variable resistor R32 is connected to the working voltage +5V. The other end of the capacitor C16 is connected to the other end of the variable resistor R32 and then grounded.