Sto circuit with self-checking function

Abstract

The utility model discloses a kind of STO circuits with self-checking function, characterized in that main control chip exports check voltage and check signal, and receives detection voltage and check signal;Signal conditioning isolation module carries out filtering and electrical isolation to check voltage;Drive control module generates drive condition signal according to effective isolation signal;Switching output module controls the on-off of safety output signal end according to drive condition signal;State feedback module feeds back the input voltage of drive control module to main control chip;Self-checking module sends to detection voltage input end after check signal is conditioned into check feedback signal when check voltage is applied;Advantages are that signal transmission stability and electrical safety are ensured by filtering and isolation, false action is avoided, drive control module state is monitored in real time and timely fault alarm, self-checking verifies input passage is complete, ensure that main control chip responds quickly when entire STO circuit is abnormal, prevent accidental torque output, improve safety and reliability.

Description

Technical Field

[0001] This utility model relates to an STO circuit, and more particularly to an STO circuit with a self-verification function. Background Technology

[0002] In industrial control, to ensure that a motor cannot output torque when it stops, a safety torque off (STO) function is typically used to prevent accidental start-up of the equipment. The STO circuit ensures that the motor's output torque returns to zero by cutting off the drive signal of the power transistor inside the driver. However, the conventional STO circuit relies on its normal operation. The main control chip is unaware of whether the STO circuit is functioning correctly. Therefore, if the STO circuit malfunctions, it may fail to properly cut off the torque output, leading to unexpected torque output. Summary of the Invention

[0003] The technical problem to be solved by this utility model is to provide an STO circuit with self-verification function, which can monitor the working status of the STO circuit in real time and notify the main control chip in time when a fault occurs, so as to ensure the reliability of the safe torque shutdown function.

[0004] The technical solution adopted by this utility model to solve the above-mentioned technical problems is as follows: an STO circuit with self-verification function, including a main control chip, a power supply module, a signal conditioning and isolation module, a drive control module, a switch output module, a status feedback module and a self-verification module; The main control chip is equipped with a first signal output terminal for generating a verification voltage, a second signal output terminal for providing a reference ground, a detection voltage input terminal, and a self-verification signal output terminal for generating a verification signal. The input terminal of the signal conditioning and isolation module is connected to the first signal output terminal and the second signal output terminal, and is used to filter the verification voltage and achieve electrical isolation, and output the conditioned isolation signal. The input terminal of the drive control module is connected to the output terminal of the signal conditioning and isolation module, and is used to generate a definite drive condition signal when the isolation signal is valid; The switch output module is provided with a control terminal and a safety output signal terminal for supplying power to the subsequent drive signal buffer. The control terminal of the switch output module is connected to the output terminal of the drive control module and is used to control the on / off connection between the power supply module and the safety output signal terminal according to the drive condition signal. The input terminal of the state feedback module is connected to the output terminal of the signal conditioning and isolation module. The state feedback module is used to detect the input voltage of the drive control module and feed it back to the detection voltage input terminal. The input terminal of the self-verification module is connected to the self-verification signal output terminal. The signal conditioning and isolation module has a filter output terminal inside. The output terminal of the self-verification module is connected to the filter output terminal. The self-verification module is used to send the verification signal to the filter output terminal when the verification voltage is applied normally, and to generate a corresponding verification feedback signal through the signal conditioning and isolation module and the status feedback module and then send it to the detection voltage input terminal.

[0005] Compared with the prior art, the advantages of this utility model are as follows: the signal conditioning and isolation module filters and isolates the verification voltage, ensuring the stability and electrical safety of the signal during transmission and avoiding erroneous actions caused by external interference; the drive control module generates a drive condition signal when the isolation signal is effective, controlling the switch output module to switch the power supply module and the safety output signal terminal on and off, thereby reliably realizing safe torque shutdown; the status feedback module detects the input voltage of the drive control module and feeds it back to the detection voltage input terminal of the main control chip, enabling the main control chip to monitor the working status of the drive control module in real time and promptly detect potential faults; when the verification voltage is applied normally, the self-verification module sends the verification signal to the filter output terminal, and generates a corresponding verification feedback signal through the signal conditioning and isolation module and the status feedback module, and then sends it to the detection voltage input terminal of the main control chip. When the verification feedback signal is lower than the preset detection threshold, the main control chip judges that the signal conditioning and isolation module, the status feedback module, the drive control module and the switch output module are all working normally, so that the main control chip can quickly take countermeasures when the STO circuit is abnormal, effectively preventing unexpected torque output caused by STO circuit failure, and improving the safety and reliability of the system.

[0006] Furthermore, the signal conditioning and isolation module includes a first resistor, a first capacitor, a second resistor, a third resistor, and a first optocoupler. One end of the first resistor is connected to the first signal output terminal. The other end of the first resistor, one end of the first capacitor, and one end of the second resistor are connected to each other. The other end of the second resistor and one end of the third resistor are connected and serve as the filter output terminal of the signal conditioning and isolation module. The other end of the third resistor is connected to pin 1 of the first optocoupler. The other end of the first capacitor and pin 2 of the first optocoupler are connected to the second signal output terminal. Pin 3 of the first optocoupler is grounded. Pin 4 of the first optocoupler serves as the output terminal of the signal conditioning and isolation module. The first resistor and the first capacitor form a low-pass filter circuit, which can effectively filter out high-frequency interference from the calibration voltage. The second and third resistors act as voltage dividers and current limiters, jointly ensuring that the first optocoupler can reliably conduct when a valid high level is input to the first signal output terminal. The first optocoupler achieves electrical isolation between the front-end control signal and the back-end drive circuit, and transmits the conditioned isolated signal to the drive control module, which is a key link in signal transmission and electrical safety.

[0007] Furthermore, the drive control module includes a second capacitor, a fourth resistor, a fifth resistor, and a first Zener diode. The anode of the first Zener diode is connected to the output terminal of the signal conditioning and isolation module and serves as the input terminal of the drive control module. The cathode of the first Zener diode is connected to one end of the fifth resistor, and the other end of the fifth resistor is connected to one end of the fourth resistor and serves as the output terminal of the drive control module. The other end of the fourth resistor and one end of the second capacitor are connected to the output terminal of the power supply module, and the other end of the second capacitor is grounded. When the signal conditioning and isolation module output is effective, the cathode potential of the first Zener diode decreases accordingly. The voltage output by the power supply module rises the cathode voltage of the first Zener diode through the fourth and fifth resistors until it conducts, thereby achieving voltage clamping. This process allows the potential at the connection point of the fourth and fifth resistors to be precisely controlled, creating conditions for the conduction of the first PNP transistor in the subsequent switching output module. The second capacitor is used to filter out power supply noise and ensure the stability of the drive level.

[0008] Furthermore, the switching output module includes a first PNP transistor and a third capacitor. The base of the first PNP transistor is connected to the output terminal of the drive control module and serves as the control terminal of the switching output module. The emitter of the first PNP transistor is connected to the output terminal of the power supply module. The collector of the first PNP transistor is connected to one end of the third capacitor and serves as the safety output signal terminal. The other end of the third capacitor is grounded. When the output voltage of the drive control module is clamped at an appropriate level, such that the emitter and base of the first PNP transistor meet the forward bias condition, the first PNP transistor conducts, thereby leading the power supply module to the safety output signal terminal to power the subsequent drive signal buffer. The third capacitor is connected between the safety output signal terminal and ground, playing a filtering and energy storage role, effectively smoothing the output voltage, suppressing instantaneous fluctuations, and ensuring the stability of the power supply.

[0009] Furthermore, the status feedback module includes a sixth resistor, a seventh resistor, a second PNP transistor, an eighth resistor, and a ninth resistor. One end of the sixth resistor is connected to the output of the signal conditioning and isolation module and serves as the input of the status feedback module. The other end of the sixth resistor and one end of the seventh resistor are connected to the base of the second PNP transistor. The other end of the seventh resistor and the emitter of the second PNP transistor are connected to the output of the power supply module. The collector of the second PNP transistor is connected to one end of the eighth resistor. The other end of the eighth resistor and one end of the ninth resistor are connected to the detection voltage input. The other end of the ninth resistor is grounded. When the input voltage of the drive control module is low, this low level turns on the second PNP transistor through the sixth resistor. This causes the voltage output from the power supply module to be divided by the eighth and ninth resistors, generating a high-level signal at the detection voltage input, which is then provided to the main control chip. The main control chip can determine whether the STO circuit is properly connected and operating by detecting the level change at the detection voltage input, thus achieving reliable monitoring of the operating status.

[0010] Furthermore, the self-verification module includes a tenth resistor, a second optocoupler, an eleventh resistor, an NPN transistor, a twelfth resistor, and a thirteenth resistor. One end of the tenth resistor and pin 4 of the second optocoupler are connected to the filter output terminal and serve as the output terminal of the self-verification module. The other end of the tenth resistor and pin 3 of the second optocoupler are connected to the second signal output terminal. Pin 1 of the second optocoupler is connected to the output terminal of the power module. Pin 2 of the second optocoupler is connected to one end of the eleventh resistor. The other end of the eleventh resistor is connected to the collector of the NPN transistor. The base of the NPN transistor, one end of the twelfth resistor, and one end of the thirteenth resistor are connected. The other end of the thirteenth resistor is connected to the self-verification signal output terminal. The emitter of the NPN transistor and the other end of the twelfth resistor are both grounded. Under the control of the main control chip, a high-level verification signal is output through the self-verification signal output terminal. This signal drives the NPN transistor to conduct through the thirteenth and twelfth resistors. The conduction of the NPN transistor provides a path for the secondary circuit of the second optocoupler, enabling it to work. If the input path between the first signal output terminal and the second signal output terminal is intact and a normal voltage is applied, the primary circuit of the second optocoupler will conduct, thereby pulling down the potential on the left side of the third resistor, which in turn forces the originally conducting first optocoupler to turn off. The turning off of the first optocoupler will cause the safety output signal terminal to disconnect and the voltage at the detection voltage input terminal to change from high to low. By detecting this series of state changes, the main control chip can confirm that the signal conditioning isolation module, the state feedback module, the drive control module, and the switch output module are all working normally.

[0011] Furthermore, the circuit also includes a reverse connection protection module, which comprises a second Zener diode and a third Zener diode. The cathode of the second Zener diode and the anode of the third Zener diode are connected to the filter output terminal, and the anode of the second Zener diode and the cathode of the third Zener diode are connected to the second signal output terminal. By connecting the second and third Zener diodes in reverse parallel, a bidirectional voltage clamping protection circuit is formed. When the first and second signal output terminals are accidentally reversed (i.e., the second signal output terminal is high and the first signal output terminal is low), the second Zener diode will conduct in the forward direction, clamping the voltage applied to the input terminals of the two optocouplers to a lower, safer level. This prevents permanent damage to the first and second optocouplers caused by large currents or high voltages due to reverse power connection, greatly enhancing the circuit's robustness and fault tolerance. Attached Figure Description

[0012] Figure 1 This is a circuit block diagram of the present invention; Figure 2This is a schematic diagram of the circuit structure of this utility model. Detailed Implementation

[0013] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0014] like Figure 1 As shown, an STO circuit with self-verification function includes a main control chip 100, a power supply module 200, a signal conditioning and isolation module 300, a drive control module 400, a switch output module 500, a status feedback module 600, and a self-verification module 700. The main control chip 100 is equipped with a first signal output terminal STO-IN for generating a verification voltage, a second signal output terminal STO-COM for providing a reference ground, a detection voltage input terminal STO1_1ms, and a self-verification signal output terminal STO_DET for generating a verification signal. The input terminal of the signal conditioning and isolation module 300 is connected to the first signal output terminal STO-IN and the second signal output terminal STO-COM. It is used to filter the verification voltage and achieve electrical isolation, and output the conditioned isolation signal. The input terminal of the drive control module 400 is connected to the output terminal of the signal conditioning and isolation module 300, and is used to generate a specific drive condition signal when the isolation signal is valid; The switch output module 500 is provided with a control terminal and a safety output signal terminal 5V_STO1 that supplies power to the subsequent drive signal buffer 800. The control terminal of the switch output module 500 is connected to the output terminal of the drive control module 400 and is used to control the on / off connection between the power supply module 200 and the safety output signal terminal 5V_STO1 according to the drive condition signal. The input terminal of the status feedback module 600 is connected to the output terminal of the signal conditioning and isolation module 300. The status feedback module 600 is used to detect the input voltage of the drive control module 400 and feed it back to the detection voltage input terminal STO1_1ms. The input terminal of the self-verification module 700 is connected to the self-verification signal output terminal STO_DET. The signal conditioning and isolation module 300 has a filter output terminal inside. The output terminal of the self-verification module 700 is connected to the filter output terminal. The self-verification module 700 is used to send the verification signal to the filter output terminal when the verification voltage is applied normally. After generating the corresponding verification feedback signal through the signal conditioning and isolation module 300 and the status feedback module 600, it is sent to the detection voltage input terminal STO1_1ms. like Figure 2As shown, the signal conditioning and isolation module 300 includes a first resistor R1, a first capacitor C1, a second resistor R2, a third resistor R3, and a first optocoupler OC1; the drive control module 400 includes a second capacitor C2, a fourth resistor R4, a fifth resistor R5, and a first Zener diode D1; the switch output module 500 includes a first PNP transistor T1 and a third capacitor C3; the status feedback module 600 includes a sixth resistor R6, a seventh resistor R7, a second PNP transistor T2, an eighth resistor R8, and a ninth resistor R9; and the self-verification module 700 includes a tenth resistor R10, a second optocoupler OC2, an eleventh resistor R11, an NPN transistor T3, a twelfth resistor R12, and a thirteenth resistor R13. One end of the first resistor R1 is connected to the first signal output terminal STO-IN. The other end of the first resistor R1 and one end of the first capacitor C1 are connected to one end of the second resistor R2. The other end of the second resistor R2 is connected to one end of the third resistor R3. The other end of the third resistor R3 is connected to pin 1 of the first optocoupler OC1. The other end of the first capacitor C1 and pin 2 of the first optocoupler OC1 are connected to the second signal output terminal STO-COM. Pin 3 of the first optocoupler OC1 is grounded. Pin 4 of the first optocoupler OC1 and the anode of the first Zener diode D1 are connected to one end of the sixth resistor R6. The cathode of a Zener diode D1 is connected to one end of the fifth resistor R5. The other end of the fifth resistor R5 and one end of the fourth resistor R4 are connected to the base of the first PNP transistor T1. The other end of the fourth resistor R4, one end of the second capacitor C2, and the emitter of the first PNP transistor T1 are connected to the output terminal P5V of the power module 200. The collector of the first PNP transistor T1 is connected to one end of the third capacitor C3 and serves as the safety output signal terminal 5V_STO1. The other end of the sixth resistor R6 and one end of the seventh resistor R7 are connected to the base of the second PNP transistor T2. The other end of resistor R7, the emitter of the second PNP transistor T2, is connected to the output terminal P5V of power module 200. The collector of the second PNP transistor T2 is connected to one end of the eighth resistor R8. The other end of the eighth resistor R8 and one end of the ninth resistor R9 are connected to the detection voltage input terminal STO1_1ms. One end of the tenth resistor R10, pin 4 of the second optocoupler OC2, and the other end of the second resistor R2 are connected. The other end of the tenth resistor R10 and pin 3 of the second optocoupler OC2 are connected to the second signal output terminal STO-COM. Pin 1 of the second optocoupler OC2 is connected to the power module 200. The output terminal P5V of 00 is connected. Pin 2 of the second optocoupler OC2 is connected to one end of the eleventh resistor R11. The other end of the eleventh resistor R11 is connected to the collector of the NPN transistor T3. The base of the NPN transistor T3, one end of the twelfth resistor R12, and one end of the thirteenth resistor R13 are connected. The other end of the thirteenth resistor R13 is connected to the self-verification signal output terminal STO_DET. The other ends of the second capacitor C2, the third capacitor C3, the ninth resistor R9, the emitter of the NPN transistor T3, and the twelfth resistor R12 are grounded respectively.

[0015] The working principle of this embodiment is as follows: Under normal circumstances, when the machine is powered on, the first signal output terminal STO-IN outputs a 24V high-level signal. This signal is first conditioned by a low-pass filter circuit composed of the first resistor R1 and the first capacitor C1 to filter out possible high-frequency interference. The filtered signal passes through the second resistor R2 and the third resistor R3. At this time, since the self-checking module 700 is not activated, the current drives pins 1 and 2 of the first optocoupler OC1 to conduct, which in turn causes pins 3 and 4 of the first optocoupler OC1 to also conduct. At this time, pin 4 of the first optocoupler OC1 is pulled down to ground. At the same time, the left side of the sixth resistor R6 and the lower side of the first Zener diode D1 are also pulled low, thereby triggering two parallel subsequent circuits.

[0016] In the first circuit, the 5V voltage output from the power module 200's output terminal P5V is filtered by the second capacitor C2 and then input to the upper side of the fourth resistor R4 and the left side of the first PNP transistor T1. At this time, the first PNP transistor T1 is not conducting, and the safety output signal terminal 5V_STO1 has no voltage. The voltage is conducted through the fourth resistor R4 to the fifth resistor R5. At this time, the upper and lower sides of the fifth resistor R5 and the upper side of the first Zener diode D1 are all at a high level. Because the first optocoupler OC1's pins 3 and 4 were previously conducting, the lower side of the first Zener diode D1 is at a low level. As the voltage across the first Zener diode D1 continues to rise until it turns on, clamping the voltage across the first Zener diode D1, the voltage across the fifth resistor R5 is also clamped, while the voltage across the fourth resistor R4 continues to rise. A voltage difference exists between the emitter and base of the first PNP transistor T1 until the emitter voltage exceeds the base voltage, exceeding the threshold, causing the first PNP transistor T1 to turn on. The safety output signal terminal 5V_STO1 is pulled high and, after being filtered by the third capacitor C3, is output to power the subsequent drive signal buffer 800.

[0017] In the second circuit, the voltage on the left side of the sixth resistor R6 is pulled low, causing the voltage on the right side of the sixth resistor R6 to also be pulled low. At this time, the emitter and base of the second PNP transistor T2 are turned on after meeting the transistor turn-on threshold. The voltage on the upper side of the eighth resistor R8 rises. After being divided by the ninth resistor R9, the voltage at the detection voltage input terminal STO1_1ms rises. The main control chip 100 detects the rise in level and can determine that the signal conditioning isolation module 300, the status feedback module 600, the drive control module 400, and the switch output module 500 are all in a normal closed conduction state.

[0018] When the main control chip 100 outputs a high-level verification signal through the self-verification signal output terminal STO_DET, the voltage on the right side of the thirteenth resistor R13 rises, and the voltage on the left side also rises accordingly. The voltage after being divided by the twelfth resistor R12 gradually rises until the NPN transistor T3 turns on. At this time, the right side of the eleventh resistor R11 is pulled low, and the left side is also pulled low, until the turn-on threshold of the second optocoupler OC2 is reached. At this time, pins 1 and 2 of the second optocoupler OC2 are turned on, and then pins 3 and 4 of the second optocoupler OC2 are also turned on. Pin 4 of the second optocoupler OC2 is pulled down, and the voltage on the left and right sides of the third resistor R3 decreases. When the voltage drops, the first optocoupler OC1, which was originally conducting, turns off. The second signal output terminal STO-COM serves as the reference ground corresponding to the first signal output terminal STO-IN. At this time, the safety output signal terminal 5V_STO1 stops outputting voltage, and the detection voltage input terminal STO1_1ms signal is pulled low. After the main control chip 100 sends a verification signal, it detects that the level of the detection voltage input terminal STO1_1ms changes from high to low as expected. This verifies that the signal conditioning isolation module 300, the status feedback module 600, the drive control module 400, and the switch output module 500 are all disconnected and functioning normally, thus completing the self-verification.

[0019] Example 2: The rest is the same as in Example 1, except that it also includes a reverse connection protection module. The reverse connection protection module includes a second Zener diode D2 and a third Zener diode D3. The cathode of the second Zener diode D2 and the anode of the third Zener diode D3 are connected to the other end of the second resistor R2. The anode of the second Zener diode D2 and the cathode of the third Zener diode D3 are connected to the second signal output terminal STO-COM.

[0020] The working principle of this embodiment is as follows: When the second signal output terminal STO-COM is mistakenly connected to a 24V high voltage, while the first signal output terminal STO-IN is connected to the reference ground in an extreme reverse connection situation, the third Zener diode D3 connected back-to-back will conduct in the forward direction, and the second Zener diode D2 will break down and conduct in the reverse direction, forming a current discharge path from the second signal output terminal STO-COM through the second Zener diode D2, the second resistor R2, the first resistor R1 to the first signal output terminal STO-IN. At this time, the voltage across pins 3 and 4 of the second optocoupler OC2 is clamped to around 0.7V, thereby effectively preventing the second optocoupler OC2 from being damaged by the reverse high voltage. At the same time, pins 1 and 2 of the first optocoupler OC1 will also be protected by the forward voltage drop characteristics of its internal light-emitting diodes, and will not be damaged by overvoltage during reverse connection, greatly enhancing the robustness and reliability of the entire interface.

Claims

1. A self-verifying STO circuit, characterized in that... It includes a main control chip, a power module, a signal conditioning and isolation module, a drive control module, a switch output module, a status feedback module, and a self-verification module; The main control chip is equipped with a first signal output terminal for generating a verification voltage, a second signal output terminal for providing a reference ground, a detection voltage input terminal, and a self-verification signal output terminal for generating a verification signal. The input terminal of the signal conditioning and isolation module is connected to the first signal output terminal and the second signal output terminal, and is used to filter the verification voltage and achieve electrical isolation, and output the conditioned isolation signal. The input terminal of the drive control module is connected to the output terminal of the signal conditioning and isolation module, and is used to generate a definite drive condition signal when the isolation signal is valid; The switch output module is provided with a control terminal and a safety output signal terminal for supplying power to the subsequent drive signal buffer. The control terminal of the switch output module is connected to the output terminal of the drive control module and is used to control the on / off connection between the power supply module and the safety output signal terminal according to the drive condition signal. The input terminal of the state feedback module is connected to the output terminal of the signal conditioning and isolation module. The state feedback module is used to detect the input voltage of the drive control module and feed it back to the detection voltage input terminal. The input terminal of the self-verification module is connected to the self-verification signal output terminal. The signal conditioning and isolation module has a filter output terminal inside. The output terminal of the self-verification module is connected to the filter output terminal. The self-verification module is used to send the verification signal to the filter output terminal when the verification voltage is applied normally, and to generate a corresponding verification feedback signal through the signal conditioning and isolation module and the status feedback module and then send it to the detection voltage input terminal.

2. The STO circuit with self-verification function according to claim 1, characterized in that... The signal conditioning and isolation module includes a first resistor, a first capacitor, a second resistor, a third resistor, and a first optocoupler. One end of the first resistor is connected to the first signal output terminal. The other end of the first resistor, one end of the first capacitor, and one end of the second resistor are connected to each other. The other end of the second resistor and one end of the third resistor are connected to each other and serve as the filter output terminal of the signal conditioning and isolation module. The other end of the third resistor is connected to pin 1 of the first optocoupler. The other end of the first capacitor and pin 2 of the first optocoupler are connected to the second signal output terminal. Pin 3 of the first optocoupler is grounded. Pin 4 of the first optocoupler serves as the output terminal of the signal conditioning and isolation module.

3. The STO circuit with self-verification function according to claim 1, characterized in that... The drive control module includes a second capacitor, a fourth resistor, a fifth resistor, and a first Zener diode. The anode of the first Zener diode is connected to the output terminal of the signal conditioning and isolation module and serves as the input terminal of the drive control module. The cathode of the first Zener diode is connected to one end of the fifth resistor. The other end of the fifth resistor is connected to one end of the fourth resistor and serves as the output terminal of the drive control module. The other end of the fourth resistor and one end of the second capacitor are connected to the output terminal of the power supply module. The other end of the second capacitor is grounded.

4. The STO circuit with self-verification function according to claim 1, characterized in that... The switching output module includes a first PNP transistor and a third capacitor. The base of the first PNP transistor is connected to the output terminal of the drive control module and serves as the control terminal of the switching output module. The emitter of the first PNP transistor is connected to the output terminal of the power supply module. The collector of the first PNP transistor is connected to one end of the third capacitor and serves as the safety output signal terminal. The other end of the third capacitor is grounded.

5. The STO circuit with self-verification function according to claim 1, characterized in that... The state feedback module includes a sixth resistor, a seventh resistor, a second PNP transistor, an eighth resistor, and a ninth resistor. One end of the sixth resistor is connected to the output terminal of the signal conditioning and isolation module and serves as the input terminal of the state feedback module. The other end of the sixth resistor and one end of the seventh resistor are connected to the base of the second PNP transistor. The other end of the seventh resistor and the emitter of the second PNP transistor are connected to the output terminal of the power supply module. The collector of the second PNP transistor is connected to one end of the eighth resistor. The other end of the eighth resistor and one end of the ninth resistor are connected to the detection voltage input terminal. The other end of the ninth resistor is grounded.

6. The STO circuit with self-verification function according to claim 1, characterized in that... The self-verification module includes a tenth resistor, a second optocoupler, an eleventh resistor, an NPN transistor, a twelfth resistor, and a thirteenth resistor. One end of the tenth resistor and pin 4 of the second optocoupler are connected to the filter output terminal and serve as the output terminal of the self-verification module. The other end of the tenth resistor and pin 3 of the second optocoupler are connected to the second signal output terminal. Pin 1 of the second optocoupler is connected to the output terminal of the power module. Pin 2 of the second optocoupler is connected to one end of the eleventh resistor. The other end of the eleventh resistor is connected to the collector of the NPN transistor. The base of the NPN transistor, one end of the twelfth resistor, and one end of the thirteenth resistor are connected. The other end of the thirteenth resistor is connected to the self-verification signal output terminal. The emitter of the NPN transistor and the other end of the twelfth resistor are both grounded.

7. The STO circuit with self-verification function according to claim 1, characterized in that... It also includes a reverse connection protection module, which includes a second Zener diode and a third Zener diode. The cathode of the second Zener diode and the anode of the third Zener diode are connected to the filter output terminal, and the anode of the second Zener diode and the cathode of the third Zener diode are connected to the second signal output terminal.

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