Motor protection circuit and control method thereof

Abstract

The application discloses a motor protection circuit and a control method thereof. The motor protection circuit comprises a contact switch and a power supply control circuit. The contact switch is electrically connected with the power supply control circuit. The power supply control circuit is electrically connected with a power supply end of a motor control interface. The power supply control circuit controls the on-off of the power supply end of the motor control interface and a first power supply according to a signal output by the contact switch. The first power supply is electrically connected with the power supply control circuit. The application can control the power-off of the motor through the power supply control circuit when the contact switch is triggered, so that the motor does not stop running due to the abnormality of a single-chip microcomputer, and damage to an instrument is avoided. The motor protection circuit further comprises a power supply switching circuit. When the single-chip microcomputer is normal, the power supply switching circuit can control a second power supply to be communicated with a motor power supply end, so that the power supply of the motor is restored. The single-chip microcomputer controls the motor to rotate reversely at the same time, so that the contact switch is released from triggering, the first power supply is switched back to supply power, and the motor resumes normal operation.

Description

Technical Field

[0001] This application relates to the field of motor protection, and in particular to a motor protection circuit and its control method. Background Technology

[0002] In scientific instruments, microcontrollers are typically used as controllers. The microcontroller controls the motor's operation, and the motor drives a lead screw to push a slider. However, the slider's movement has a limit; at a critical point, a feedback signal is needed to the microcontroller, indicating that the slider has reached the critical point and should not continue or that the motor needs to reverse. Currently, a contact switch is usually placed at the critical point, connected to the microcontroller. When the slider triggers the contact switch, it outputs a "movement complete" signal to the microcontroller, indicating that the slider has reached its destination, thus allowing the microcontroller to control the motor to stop or reverse. However, if the microcontroller malfunctions (including its own failure or external interference), these contact switch feedback signals may not be received by the microcontroller, causing the motor to continue running and the slider to collide with other structures in the instrument, potentially damaging it. Summary of the Invention

[0003] In view of this, this application provides a motor protection circuit and its control method to solve the problem in the existing microcontroller-controlled motor operation circuit that the movement positioning signal cannot be received due to a problem with the microcontroller, which causes the motor to fail to stop and ultimately damages the instrument.

[0004] The following is a brief overview of this application to provide a basic understanding of certain aspects thereof. It should be understood that this overview is not an exhaustive summary of this application. It is not intended to identify key or essential parts of this application, nor is it intended to limit the scope of this application. Its purpose is merely to present certain concepts in a simplified form as a prelude to the more detailed description that follows.

[0005] According to a first aspect of this application, a motor protection circuit is provided, including a contact switch and a power control circuit. The contact switch is electrically connected to the power control circuit, and the power control circuit is electrically connected to the power supply terminal of a motor control interface. The power control circuit controls the switching between the power supply terminal of the motor control interface and a first power supply based on a signal output by the contact switch. The first power supply is electrically connected to the power control circuit.

[0006] In some embodiments, the motor protection circuit further includes a microcontroller and a power switching circuit. The microcontroller is electrically connected to the contact switch and the power switching circuit. The power switching circuit is electrically connected to the power supply terminal of the motor control interface. The microcontroller controls the switching between the power supply terminal of the motor control interface and the second power supply through the power switching circuit based on the signal output by the contact switch. The second power supply is electrically connected to the power switching circuit.

[0007] Furthermore, the motor protection circuit also includes a motor reverse control circuit electrically connected to the microcontroller. When the microcontroller controls the power supply terminal of the motor control interface to connect to the second power supply, the microcontroller controls the motor to reverse through the motor reverse control circuit.

[0008] In some embodiments, the power control circuit includes a logic chip and a control switch that are electrically connected.

[0009] The contact switch includes a first contact switch and a second contact switch. The logic chip is electrically connected to the first contact switch and the second contact switch respectively, and controls the control switch to open when it receives a contact signal output by the first contact switch or the second contact switch.

[0010] The control switch is electrically connected to the first power supply and the power supply terminal of the motor control interface, respectively.

[0011] Furthermore, the control switch is a PMOS transistor, and a third optocoupler is connected between the logic chip and the PMOS transistor;

[0012] The positive terminals of the first contact switch and the second contact switch are electrically connected to the input terminal of the logic chip, respectively. The positive terminal of the first contact switch is electrically connected to the power supply of the first contact switch through a first pull-up resistor. The positive terminal of the second contact switch is electrically connected to the power supply of the second contact switch through a second pull-up resistor. The negative terminals of the first contact switch and the second contact switch are both grounded.

[0013] The output terminal of the logic chip is electrically connected to the positive input terminal of the third optocoupler through a first current-limiting resistor, and both the negative input terminal and the negative output terminal of the third optocoupler are grounded;

[0014] The positive output of the third optocoupler isolator is electrically connected to the gate of the PMOS transistor through a first voltage divider resistor. The gate of the PMOS transistor is electrically connected to the first power supply through a second voltage divider resistor. The source of the PMOS transistor is electrically connected to the first power supply. The drain of the PMOS transistor is electrically connected to the power supply terminal of the motor control interface.

[0015] In some embodiments, the positive terminals of the first contact switch and the second contact switch are electrically connected to the input terminals of the microcontroller, respectively.

[0016] The power switching circuit includes a switching switch and a relay. The coils of the switching switch and the relay are electrically connected. The two ends of the normally open contact of the relay are electrically connected to the power supply terminal of the motor control interface and the second power supply, respectively.

[0017] Furthermore, the switching switch is an NMOS transistor, and a second optocoupler is connected between the NMOS transistor and the microcontroller;

[0018] The output terminal of the microcontroller is electrically connected to the negative input terminal of the second optocoupler. The positive input terminal of the second optocoupler is electrically connected to the power supply of the second optocoupler input terminal through the second current-limiting resistor. The positive output terminal of the second optocoupler is electrically connected to the power supply of the second optocoupler output terminal. The negative output terminal of the second optocoupler is grounded through the third voltage divider resistor.

[0019] The negative output of the second optocoupler is simultaneously connected to the gate of the NMOS transistor through a fourth voltage divider resistor. The source of the NMOS transistor is grounded, the drain of the NMOS transistor is connected to the negative terminal of the relay coil, and the positive terminal of the relay coil is connected to the second power supply.

[0020] In some embodiments, the microcontroller is electrically connected to the direction control terminal of the motor control interface via a first optocoupler, the output terminal of the microcontroller is electrically connected to the negative input terminal of the first optocoupler, the positive input terminal of the first optocoupler is electrically connected to the power supply of the input terminal of the first optocoupler via a third current-limiting resistor, the positive output terminal of the first optocoupler is electrically connected to the power supply of the output terminal of the first optocoupler via a fifth voltage-dividing resistor, the positive output terminal of the first optocoupler is also electrically connected to the direction control terminal of the motor control interface, and the negative output terminal of the first optocoupler is grounded.

[0021] According to a second aspect of this application, a control method for a motor protection circuit as described in the first aspect of this application is provided, comprising the following steps:

[0022] S1: Detect whether the power control circuit receives a contact signal from the first contact switch or the second contact switch. If the contact signal is received, control the power supply terminal of the motor control interface to disconnect from the first power supply.

[0023] S2: The microcontroller detects whether it receives a contact signal from the first contact switch or the second contact switch. If the microcontroller does not receive the contact signal, it performs a self-test reset. If the microcontroller receives the contact signal or receives the contact signal after the self-test reset, it controls the power supply terminal of the motor control interface to connect with the second power supply and makes the motor run in reverse.

[0024] S3: After the motor reverses, the first contact switch and the second contact switch stop sending contact signal, the power control circuit controls the power terminal of the motor control interface to connect with the first power supply, and the microcontroller controls the power terminal of the motor control interface to disconnect from the second power supply.

[0025] In some embodiments, step S2, in which the microcontroller performs a self-test reset, includes: software reset of the microcontroller and determining whether the microcontroller can receive the contact signal. If the microcontroller can receive the contact signal, the microcontroller reset is successful. If the microcontroller still cannot receive the contact signal after multiple software resets, the microcontroller reset fails.

[0026] The motor protection circuit and control method provided in this application connect a contact switch to a power control circuit. When the contact switch is triggered, the power control circuit controls the first power supply to disconnect from the power supply terminal of the motor control interface, thereby achieving motor protection. At the same time, the contact switch sends a contact-in signal to the microcontroller. Under normal conditions, the microcontroller controls the second power supply to connect to the power supply terminal of the motor control interface through a power switching circuit, thereby restoring the power supply to the motor. The microcontroller simultaneously controls the motor to rotate in reverse so that after the contact switch is de-triggered, it switches back to the first power supply, allowing the motor to resume normal operation. Attached Figure Description

[0027] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. The above and other objects, features, and advantages of this application will become clearer through the drawings. The same reference numerals indicate the same parts in all the drawings. The drawings are not intentionally drawn to scale to actual size; the focus is on illustrating the main points of this application.

[0028] Figure 1 A schematic diagram of a motor protection circuit provided in an embodiment of this application;

[0029] Figure 2A structural diagram of a motor protection circuit provided in an embodiment of this application;

[0030] Figure 3 A flowchart illustrating a control method for a motor protection circuit provided in an embodiment of this application. Detailed Implementation

[0031] The technical solutions in the embodiments of this application will now be described with reference to the accompanying drawings.

[0032] It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, relational terms such as "first," "second," etc., in the description of this application are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one…" does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0033] Furthermore, the term "and / or" in this application is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, A and / or B can represent three situations: A exists alone, A and B exist simultaneously, and B exists alone.

[0034] Exemplary embodiments of this application will be described below with reference to the accompanying drawings. For clarity and brevity, not all features of the actual embodiments are described in the specification. However, it should be understood that many embodiment-specific decisions can be made in the development of any such actual embodiment to achieve the developer's specific goals, and these decisions may vary as the embodiments differ.

[0035] It should also be noted that, in order to avoid obscuring this application with unnecessary details, only the device structure closely related to the solution according to this application is shown in the accompanying drawings, while other details that are not closely related to this application are omitted.

[0036] It should be understood that this application is not limited to the described embodiments by virtue of the following description with reference to the accompanying drawings. In this document, embodiments may be combined with each other, features may be substituted or borrowed between different embodiments, and one or more features may be omitted in one embodiment, where feasible.

[0037] Figure 1 A schematic diagram of a motor protection circuit provided in an embodiment of this application; Figure 2 This is a structural diagram of a motor protection circuit provided in an embodiment of this application.

[0038] Please see Figure 1 and Figure 2 The motor protection circuit provided in this application includes a contact switch and a power control circuit. The contact switch is electrically connected to the power control circuit, and the power control circuit is electrically connected to the power supply terminal of the motor control interface CN20. The power control circuit controls the switching between the power supply terminal of the motor control interface CN20 and a first power supply according to the signal output by the contact switch. The first power supply is electrically connected to the power control circuit.

[0039] Specifically, in this embodiment, the power control circuit includes an electrically connected logic chip U4 and a control switch. The contact switch includes a first contact switch CN3 and a second contact switch CN4. The logic chip U4 is electrically connected to the first contact switch CN3 and the second contact switch CN4 respectively. When a contact signal is received from the first contact switch CN3 or the second contact switch CN4, the control switch is disconnected. The contact signal is a signal indicating that the first contact switch CN3 or the second contact switch CN4 has been touched. The control switch is electrically connected to the power supply terminal of the first power supply and the motor control interface CN20 respectively.

[0040] Preferably, in this embodiment of the application, the control switch is a PMOS transistor Q3, and a third optocoupler U3 is connected between the logic chip U4 and the PMOS transistor Q3;

[0041] The positive terminals of the first contact switch CN3 and the second contact switch CN4 are electrically connected to the input terminal of the logic chip U4, respectively. The positive terminal of the first contact switch CN3 is electrically connected to the first contact switch power supply through the first pull-up resistor R74. The positive terminal of the second contact switch CN4 is electrically connected to the second contact switch power supply through the second pull-up resistor R78. The negative terminals of the first contact switch CN3 and the second contact switch CN4 are both grounded.

[0042] The output terminal of the logic chip U4 is electrically connected to the positive input terminal of the third optocoupler U3 through the first current-limiting resistor R75. The negative input terminal and the negative output terminal of the third optocoupler U3 are both grounded.

[0043] The positive output of the third optocoupler isolator U3 is electrically connected to the gate of PMOS transistor Q3 through the first voltage divider resistor R76. The gate of PMOS transistor Q3 is electrically connected to the first power supply through the second voltage divider resistor R77. The source of PMOS transistor Q3 is electrically connected to the first power supply. The drain of PMOS transistor Q3 is electrically connected to the power supply terminal of the motor control interface CN20.

[0044] In this embodiment, the third optocoupler U3 is used to isolate the logic chip U4 from the PMOS transistor Q3, prevent the first power supply from interfering with the logic chip U4 and other weak current components, and prevent large current or voltage surges from damaging the components.

[0045] In this embodiment, when the first contact switch CN3 or the second contact switch CN4 is triggered, the positive terminal of the first contact switch CN3 or the second contact switch CN4 outputs a low-level contact signal to the logic chip U4. After receiving the contact signal, the logic chip U4 outputs a low level, the positive and negative output terminals of the third optocoupler U3 are cut off, the gate of the PMOS transistor Q3 is at a high level, the PMOS transistor Q3 is cut off, and the first power supply is disconnected from the power supply terminal of the motor control interface CN20.

[0046] In this embodiment, when neither the first contact switch CN3 nor the second contact switch CN4 is triggered, due to the action of the first pull-up resistor R74 and the second pull-up resistor R78, the positive terminals of both the first contact switch CN3 and the second contact switch CN4 output a high level, the output terminal of the logic chip U4 outputs a high level, the input positive terminal and the input negative terminal of the optocoupler U3 have a voltage difference, causing the internally connected light-emitting diode to light up, the output positive terminal and the output negative terminal of the optocoupler U3 are connected, the gate of the PMOS transistor Q3 is at a low level, the PMOS transistor Q3 is turned on, the first power supply is connected to the power supply terminal of the motor control interface CN20, and the motor runs normally.

[0047] In this embodiment of the application, the motor protection circuit further includes a microcontroller U13 and a power switching circuit. The microcontroller U13 is electrically connected to the contact switch and the power switching circuit. The power switching circuit is electrically connected to the power supply terminal of the motor control interface CN20. The microcontroller controls the switching between the power supply terminal of the motor control interface CN20 and the second power supply through the power switching circuit according to the signal output by the contact switch. The second power supply is electrically connected to the power switching circuit.

[0048] Specifically, the positive terminals of the first contact switch CN3 and the second contact switch CN4 are electrically connected to the input terminal of the microcontroller U13, respectively; the power switching circuit includes a switching switch and a relay K1, the coils of the switching switch and the relay K1 are electrically connected, and the two ends of the normally open contact of the relay K1 are electrically connected to the power supply terminal of the motor control interface CN20 and the second power supply, respectively.

[0049] Preferably, in this embodiment of the application, the switching switch can be an NMOS transistor Q2, and a second optocoupler U2 is connected between the NMOS transistor Q2 and the microcontroller U13;

[0050] The output terminal of the microcontroller U13 is electrically connected to the negative input terminal of the second optocoupler U2. The positive input terminal of the second optocoupler U2 is electrically connected to the power supply of the second optocoupler input terminal through the second current-limiting resistor R71. The positive output terminal of the second optocoupler U2 is electrically connected to the power supply of the second optocoupler output terminal. The negative output terminal of the second optocoupler U2 is grounded through the third voltage divider resistor R73.

[0051] The negative output of the second optocoupler U2 is simultaneously connected to the gate of the NMOS transistor Q2 through the fourth voltage divider resistor R72. The source of the NMOS transistor Q2 is grounded, the drain of the NMOS transistor Q2 is connected to the negative terminal of the relay K1 coil, and the positive terminal of the relay K1 coil is connected to the second power supply.

[0052] In this embodiment, the second optocoupler U2 is used to isolate the microcontroller U13 from the NMOS transistor Q2, preventing the second power supply from interfering with the microcontroller U13 and other low-voltage components, and preventing large current or voltage surges from damaging the components.

[0053] In this embodiment, after the first contact switch CN3 or the second contact switch CN4 inputs a low-level contact signal to the microcontroller U13, the microcontroller U13 outputs a low-level power switching signal. The voltage difference between the positive and negative input terminals of the second optocoupler U2 causes the internally connected LED to light up. The positive and negative output terminals of the second optocoupler U2 are connected, the gate of the NMOS transistor Q2 is at a high level, the NMOS transistor Q2 is turned on, the coil of the relay K1 is energized, the normally open contact of the relay K1 is closed, and the power supply terminal of the motor control interface CN20 is connected to the second power supply.

[0054] Furthermore, in this embodiment, the motor protection circuit also includes a motor reverse control circuit electrically connected to the microcontroller U13. When the power supply terminal of the motor control interface CN20 controlled by the microcontroller U13 is connected to the second power supply, the microcontroller U13 controls the motor to reverse through the motor reverse control circuit. The motor reverse control circuit includes a first optocoupler U12 electrically connected to the direction control terminal of the microcontroller U13 and the motor control interface CN20 respectively. The output terminal of the microcontroller U13 is electrically connected to the negative input terminal of the first optocoupler U12. The positive input terminal of the first optocoupler U12 is electrically connected to the power supply of the input terminal of the first optocoupler U12 through the third current-limiting resistor R80. The positive output terminal of the first optocoupler U12 is electrically connected to the power supply of the output terminal of the first optocoupler U12 through the fifth voltage-dividing resistor R79. The positive output terminal of the first optocoupler U12 is also electrically connected to the direction control terminal of the motor control interface CN20. The negative output terminal of the first optocoupler U12 is grounded.

[0055] When the microcontroller U12 controls the power supply terminal of the motor control interface to connect with the second power supply, the microcontroller U12 simultaneously outputs a low-level reverse signal. The positive and negative output terminals of the first optocoupler U12 are connected, and the positive output terminal of the first optocoupler U12 outputs a low-level signal to the direction control terminal of the motor control interface CN20, thereby controlling the motor to run in reverse.

[0056] Based on the motor protection circuit provided in the embodiments of this application, the embodiments of this application also provide a control method applied to the aforementioned motor protection circuit, such as... Figure 3 As shown, the specific steps include the following:

[0057] S1: Detect whether the power control circuit receives a contact signal from the first contact switch or the second contact switch. If a contact signal is received, disconnect the power supply terminal of the motor control interface from the first power supply.

[0058] In this embodiment, if the power control circuit receives a contact-in signal from the first contact switch CN3 or the second contact switch CN4, it indicates that the device driven by the motor, such as the slider, has reached a critical point. Continued operation would cause the slider to collide with other structures of the instrument, resulting in damage. Therefore, it is necessary to control the motor to stop or reverse its operation. In the prior art, microcontrollers are often used to control motor operation. However, as described in the background section, in the event of a microcontroller malfunction or external interference, it cannot control the motor in a timely manner. Therefore, this embodiment employs a power control circuit to control the motor power supply. The power control circuit can disconnect the power supply terminal of the motor control interface CN20 from the first power supply when it receives a contact-in signal from the first contact switch CN3 or the second contact switch CN4, thereby stopping the motor and protecting it.

[0059] S2: The microcontroller detects whether it receives a contact signal from the first or second contact switch. If the microcontroller does not receive a contact signal, it performs a self-test reset. If the microcontroller receives a contact signal or receives a contact signal after the self-test reset, it connects the power supply terminal of the motor control interface to the second power supply and makes the motor run in reverse.

[0060] In this embodiment, the contact switch sends a contact-ready signal to the power control circuit simultaneously or subsequently, and also sends a contact-ready signal to the microcontroller U13. Since the microcontroller U13 may malfunction or fail to receive the contact-ready signal due to external interference, it first needs to check whether it receives the contact-ready signal from the first contact switch CN3 or the second contact switch CN4. If the microcontroller U13 does not receive the contact-ready signal, it indicates that the microcontroller U13 may indeed have a malfunction or external interference. To further determine the type of problem, the microcontroller U13 can be self-tested and reset. If the microcontroller U13 resets successfully, it indicates that the aforementioned problem may be due to external interference. If the microcontroller U13 fails to reset successfully, it indicates that the aforementioned problem is highly likely to be a malfunction of the microcontroller U13 itself.

[0061] In this embodiment of the application, the self-test reset of the microcontroller U13 can be performed by: software reset of the microcontroller U13 and determination of whether the microcontroller U13 can receive the contact signal. If the contact signal can be received, the microcontroller U13 is successfully reset; if the microcontroller U13 still cannot receive the contact signal after multiple software resets, the microcontroller U13 reset fails.

[0062] It is worth noting that, in this embodiment of the application, the method for performing a self-test reset on the microcontroller U13 is not limited to the above-described operation.

[0063] In this embodiment, after the microcontroller U13 is functioning normally or recovers to normal after a self-test reset, it can receive a contact signal from the first contact switch CN3 or the second contact switch CN4. This allows it to control the power supply terminal of the motor control interface to connect to the second power supply via the power switching circuit, thereby supplying power to the motor. Furthermore, in this embodiment, to deactivate the first contact switch CN3 or the second contact switch CN4, the microcontroller U13 also simultaneously controls the motor to rotate in reverse.

[0064] S3: After the motor reverses, the first and second contact switches stop sending contact signal, the power control circuit connects the power supply terminal of the motor control interface to the first power supply, and the microcontroller disconnects the power supply terminal of the motor control interface from the second power supply.

[0065] In this embodiment, after the motor reverses, the collision between the slider and the contact switch is released, the first contact switch CN3 and the second contact switch CN4 stop sending contact signal, the signal received by the power control circuit switches from low level to high level, the logic chip U4 outputs a high level, the input positive and input negative terminals of the optocoupler U3 have a voltage difference that causes the internally connected light-emitting diode to light up, the output positive and output negative terminals of the optocoupler U3 are connected, the gate of the PMOS transistor Q3 is at a low level, the PMOS transistor Q3 is turned on, the first power supply is connected to the power supply terminal of the motor control interface CN20, and the motor resumes normal operation.

[0066] In this embodiment, after the first contact switch CN3 and the second contact switch CN4 stop sending contact signal, the signal received by the microcontroller U13 switches from low level to high level, so it will also control the power supply terminal of the motor control interface controlled by the power switching circuit to disconnect from the second power supply.

[0067] The motor protection circuit and control method provided in this application include a power control circuit with a logic chip. The power control circuit controls the disconnection of the first power supply and the motor control interface based on the contact signal sent by the contact switch, thereby achieving motor protection. When the microcontroller is normal or recovers to normal through self-test reset, the microcontroller can control the connection of the second power supply and the motor control interface based on the contact signal sent by the contact switch, and simultaneously realize the reverse rotation of the motor, thereby de-triggering the contact switch. When the power control circuit cannot receive the contact signal, it controls the connection of the first power supply and the motor control interface, thereby restoring the motor to normal operation, thus achieving protection of the motor and the instrument when the microcontroller malfunctions.

[0068] The above-described embodiments are merely specific implementations of this application, used to illustrate the technical solutions of this application, and are not intended to limit it. The scope of protection of this application is not limited thereto. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments within the scope of the technology disclosed in this application, or make equivalent substitutions for some of the technical features; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be covered within the scope of protection of this application.

Claims

1. A motor protection circuit, characterized in that, It includes a contact switch and a power control circuit. The contact switch is electrically connected to the power control circuit, and the power control circuit is electrically connected to the power supply terminal of the motor control interface. The power control circuit controls the switching between the power supply terminal of the motor control interface and a first power supply according to the signal output by the contact switch. The first power supply is electrically connected to the power control circuit. It also includes a microcontroller and a power switching circuit. The microcontroller is electrically connected to the contact switch and the power switching circuit. The power switching circuit is electrically connected to the power supply terminal of the motor control interface. The microcontroller controls the switching between the power supply terminal of the motor control interface and the second power supply through the power switching circuit according to the signal output by the contact switch. The second power supply is electrically connected to the power switching circuit. The power control circuit includes a logic chip and a control switch that are electrically connected. The contact switch includes a first contact switch and a second contact switch. The logic chip is electrically connected to the first contact switch and the second contact switch respectively, and controls the control switch to open when it receives a contact signal output by the first contact switch or the second contact switch. The control switch is electrically connected to the first power supply and the power supply terminal of the motor control interface, respectively; the control switch is a PMOS transistor, and a third optocoupler is connected between the logic chip and the PMOS transistor; The positive terminals of the first contact switch and the second contact switch are electrically connected to the input terminal of the logic chip, respectively. The positive terminal of the first contact switch is electrically connected to the power supply of the first contact switch through a first pull-up resistor. The positive terminal of the second contact switch is electrically connected to the power supply of the second contact switch through a second pull-up resistor. The negative terminals of the first contact switch and the second contact switch are both grounded. The output terminal of the logic chip is electrically connected to the positive input terminal of the third optocoupler through a first current-limiting resistor, and both the negative input terminal and the negative output terminal of the third optocoupler are grounded; The positive output of the third optocoupler isolator is electrically connected to the gate of the PMOS transistor through a first voltage divider resistor. The gate of the PMOS transistor is electrically connected to the first power supply through a second voltage divider resistor. The source of the PMOS transistor is electrically connected to the first power supply. The drain of the PMOS transistor is electrically connected to the power supply terminal of the motor control interface.

2. The motor protection circuit as described in claim 1, characterized in that, It also includes a motor reverse control circuit electrically connected to the microcontroller. When the microcontroller controls the power supply terminal of the motor control interface to be connected to the second power supply, the microcontroller controls the motor to reverse through the motor reverse control circuit.

3. The motor protection circuit as described in claim 1, characterized in that, The positive terminals of the first contact switch and the second contact switch are electrically connected to the input terminals of the microcontroller, respectively. The power switching circuit includes a switching switch and a relay. The coils of the switching switch and the relay are electrically connected. The two ends of the normally open contact of the relay are electrically connected to the power supply terminal of the motor control interface and the second power supply, respectively.

4. The motor protection circuit as described in claim 3, characterized in that, The switching switch is an NMOS transistor, and a second optocoupler is connected between the NMOS transistor and the microcontroller. The output terminal of the microcontroller is electrically connected to the negative input terminal of the second optocoupler. The positive input terminal of the second optocoupler is electrically connected to the power supply of the second optocoupler input terminal through the second current-limiting resistor. The positive output terminal of the second optocoupler is electrically connected to the power supply of the second optocoupler output terminal. The negative output terminal of the second optocoupler is grounded through the third voltage divider resistor. The negative output of the second optocoupler is simultaneously connected to the gate of the NMOS transistor through a fourth voltage divider resistor. The source of the NMOS transistor is grounded, the drain of the NMOS transistor is connected to the negative terminal of the relay coil, and the positive terminal of the relay coil is connected to the second power supply.

5. The motor protection circuit as described in claim 2, characterized in that, The microcontroller is electrically connected to the direction control terminal of the motor control interface via a first optocoupler isolator. The output terminal of the microcontroller is electrically connected to the negative input terminal of the first optocoupler isolator. The positive input terminal of the first optocoupler isolator is electrically connected to the power supply of the input terminal of the first optocoupler isolator via a third current-limiting resistor. The positive output terminal of the first optocoupler isolator is electrically connected to the power supply of the output terminal of the first optocoupler isolator via a fifth voltage-dividing resistor. The positive output terminal of the first optocoupler is also electrically connected to the direction control terminal of the motor control interface. The negative output terminal of the first optocoupler is grounded.

6. A control method for a motor protection circuit as described in any one of claims 1-5, characterized in that, Includes the following steps: S1: Detect whether the power control circuit receives a contact signal from the first contact switch or the second contact switch. If the contact signal is received, control the power supply terminal of the motor control interface to disconnect from the first power supply. S2: The microcontroller detects whether it has received a contact signal from the first contact switch or the second contact switch. If the microcontroller has not received the contact signal, it performs a self-test and reset. If the microcontroller receives the contact signal or receives the contact signal after self-test reset, it controls the power supply terminal of the motor control interface to connect with the second power supply and causes the motor to run in reverse. S3: After the motor reverses, the first contact switch and the second contact switch stop sending contact signal, the power control circuit controls the power terminal of the motor control interface to connect with the first power supply, and the microcontroller controls the power terminal of the motor control interface to disconnect from the second power supply.

7. The control method for the motor protection circuit as described in claim 6, characterized in that, In step S2, the microcontroller performs a self-test reset, which includes: software reset of the microcontroller and determining whether the microcontroller can receive the contact signal. If the microcontroller can receive the contact signal, the microcontroller reset is successful; if the microcontroller still cannot receive the contact signal after multiple software resets, the microcontroller reset fails.

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