Safe Torque Off Circuits and Systems

Abstract

The present invention discloses a safety torque off circuit and system, the safety torque off circuit comprises an input module, a conversion module and an output module, wherein: the input module is connected to the output module via the conversion module; the input module is used to receive an STO signal sent by an external control system, and output the voltage of the STO signal to the conversion module; the conversion module is used to convert the voltage of the STO signal into a preset output voltage, and output the preset output voltage to the output module; the output module is used to output the preset output voltage to a driver board of a driver, so as to control the driver to start or stop the motor by the preset output voltage. The present invention can ensure torque off when the input STO signal is for the motor to stop, prevent the motor from starting accidentally, and improve safety.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic circuits, and in particular to a safety torque off circuit and system. Background Art

[0002] At present, in the plastic machinery industry, in order to prevent accidents caused by accidental motor starting, relevant requirements for functional safety are proposed for drive products (inverter, servo drive, etc.). STO (Safe Torque Off) is one of the safety functions. The safe torque off function prevents the motor from generating torque when it stops, thereby improving safety performance.

[0003] At present, the existing safe torque off circuit generally adopts a switch control method, and uses the input STO signal as a control signal to control the conduction or shutdown of the switch tube inside the safe torque off circuit. When the voltage of the input STO signal is high (STO signal is on), the switch tube is turned on, and the safe torque off circuit outputs the preset voltage through the switch tube from the internal power supply, and the driver can operate normally; when the voltage of the input STO signal is low (STO signal is off), the switch tube is turned off, and the safe torque off circuit has no voltage output, and the driver remains in the safe torque off state. However, when the switch tube inside the safe torque off circuit fails, one of the failure modes is the short circuit of the switch tube. When this failure mode occurs, when the voltage of the input STO signal is low, the safe torque off circuit will also output the preset voltage through the short-circuited switch tube from the internal power supply, causing the driver to be unable to enter the safe torque off state. At this time, the driver can be operated through the driver's software or enable switch, which has certain safety hazards. Summary of the invention

[0004] The main purpose of the present invention is to provide a safe torque cut-off circuit and system, which aims to ensure torque cut-off when the motor stops and prevent the motor from starting accidentally.

[0005] In order to achieve the above object, the present invention provides a safety torque off circuit, including an input module, a conversion module and an output module, wherein:

[0006] The input module is connected to the output module via the conversion module;

[0007] The input module is used to receive the STO signal sent by the external control system and output the voltage of the STO signal to the conversion module;

[0008] The conversion module is used to convert the voltage of the STO signal into a preset output voltage, and output the preset output voltage to the output module;

[0009] The output module is used to output the preset output voltage to the driver board of the driver, so as to control the driver to drive the motor to start or stop the motor starting through the preset output voltage.

[0010] Preferably, the input module includes a first input protection circuit, which includes a first TVS protection device and a first diode, one end of the first TVS protection device is connected to the positive electrode of the voltage of the STO signal, the other end of the first TVS protection device is connected to the negative electrode of the voltage of the STO signal, and the negative electrode of the voltage of the STO signal is grounded; the anode of the first diode is connected to the positive electrode of the voltage of the STO signal, and the cathode of the first diode is connected to the conversion module.

[0011] Preferably, the conversion module includes a first pre-stage voltage stabilization circuit, a first switch driving circuit, a first voltage transformation isolation circuit, and a first rectifier circuit, wherein:

[0012] The first front-stage voltage stabilizing circuit is used to stabilize the voltage of the STO signal to obtain a stable output voltage;

[0013] The first switch driving circuit is used to process the stable output voltage to obtain a complementary square wave signal, and amplify the complementary square wave signal;

[0014] The first voltage conversion isolation circuit is used to process the amplified complementary square wave signal to obtain a square wave voltage isolated from the input STO signal;

[0015] The first rectifier circuit is used to rectify the square wave voltage to obtain a DC output voltage.

[0016] Preferably, the first pre-stage voltage stabilization circuit comprises a first capacitor, a second capacitor and a first voltage stabilizer, one end of the first capacitor is connected to the cathode of the first diode, and the other end of the first capacitor is grounded; the input end of the first voltage stabilizer is connected to the cathode of the first diode, the ground end of the first voltage stabilizer is grounded, the output end of the first voltage stabilizer is grounded via the second capacitor, and the output end of the first voltage stabilizer is also connected to the first switch driving circuit;

[0017] The first switch driving circuit includes a first resistor, a fifth capacitor, a sixth capacitor, a switch signal generator, a first transistor, a second transistor, a third transistor and a fourth transistor. The switch signal generator includes a first adjustment pin, a second adjustment pin, a third adjustment pin, an input pin, a first output pin and a second output pin. The first adjustment pin is connected to the third adjustment pin via the fifth capacitor, the second adjustment pin is connected to the third adjustment pin via the first resistor, the output end of the first voltage regulator is connected to the input pin, the output end of the first voltage regulator is also grounded via the sixth capacitor, and the sixth The capacitor is connected in parallel with the input pin; the first output pin is connected with the base of the first transistor and the base of the second transistor, the second output pin is connected with the base of the third transistor and the base of the fourth transistor, the collector of the first transistor and the collector of the third transistor are connected to the output end of the voltage regulator, the emitter of the first transistor and the emitter of the second transistor are connected to the first voltage conversion isolation circuit, the emitter of the third transistor and the emitter of the fourth transistor are connected to the first voltage conversion isolation circuit, and the collector of the second transistor and the collector of the fourth transistor are grounded;

[0018] The first transformer isolation circuit includes an isolation transformer, the emitter of the first transistor and the emitter of the second transistor are connected to one end of the primary end of the isolation transformer, the emitter of the third transistor and the emitter of the fourth transistor are connected to the other end of the primary end of the isolation transformer, and the secondary end of the isolation transformer is connected to the first rectifier circuit;

[0019] The first rectifier circuit includes a first double diode and a second double diode. The secondary end of the isolation transformer is connected to the anodes of the first double diode and the second double diode respectively. The cathodes of the first double diode and the second double diode are connected to the output module.

[0020] Preferably, the output module includes a first post-stage voltage stabilization circuit, which includes a seventh capacitor, an eighth capacitor and a second voltage regulator, the input end of the second voltage regulator is connected to the cathodes of the first double diode and the second double diode, the input end of the second voltage regulator is also grounded via the seventh capacitor, the ground end of the second voltage regulator is grounded, the output end of the second voltage regulator is grounded via the eighth capacitor, and the output end of the second voltage regulator is also connected to the driving board of the driver to control the opening and closing of the driving board IGBT.

[0021] Preferably, the output module also includes a first voltage comparison circuit, which includes: a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a nineteenth resistor, a thirteenth capacitor, a fourteenth capacitor and a first comparator. The output end of the second voltage regulator is connected to the negative pin of the first comparator via the fifth resistor, and the negative pin of the first comparator is also grounded via the sixth resistor and the fourteenth capacitor in parallel. The preset reference voltage is connected to the positive pin of the first comparator via the fourth resistor, and the positive pin of the first comparator is also grounded via the third resistor and the thirteenth capacitor in parallel. The output end of the first comparator is connected to the preset reference voltage via the nineteenth resistor, and the output end of the first comparator is also connected to the mainboard of the driver to output a first feedback signal to the control chip of the driver.

[0022] Preferably, the output module further includes a third voltage comparison circuit, an optocoupler isolation circuit, and a transistor switch circuit, wherein:

[0023] The third voltage comparison circuit includes: an eleventh resistor, a twelfth resistor, a thirteenth resistor, a fourteenth resistor, a seventeenth capacitor, an eighteenth capacitor and a second comparator, the output end of the second voltage regulator is connected to the negative pin of the second comparator via the thirteenth resistor, the negative pin of the first comparator is also grounded via the fourteenth resistor and the eighteenth capacitor connected in parallel, the preset reference voltage is connected to the positive pin of the second comparator via the twelfth resistor, the positive pin of the second comparator is also grounded via the eleventh resistor and the seventeenth capacitor connected in parallel, and the output end of the second comparator is also connected to the optocoupler isolation circuit;

[0024] The optical coupling isolation circuit includes a twenty-first resistor, a twenty-second resistor, a twenty-second capacitor and a photocoupler, the output end of the second comparator is connected to pin 2 of the photocoupler via the twenty-first resistor, pin 1 of the photocoupler is connected to a preset reference voltage, the preset reference voltage is further connected to pin 2 of the photocoupler via the twenty-second resistor and the twenty-second capacitor connected in parallel, and pins 3 and 4 of the photocoupler are connected to the transistor switch circuit;

[0025] The transistor switch circuit includes a twenty-third resistor, a twenty-fourth resistor, a seventh diode, a ninth transistor and a resettable fuse. Pin 3 of the photocoupler is grounded via the twenty-fourth resistor, pin 4 of the photocoupler is connected to the base of the ninth transistor, pin 4 of the photocoupler is also connected to a preset power supply via the twenty-third resistor, the preset power supply is connected to the emitter of the ninth transistor, the preset power supply is also connected to the cathode of the seventh diode, the anode of the seventh diode is connected to the collector of the ninth transistor, and the collector of the ninth transistor is also connected to the external control system via the resettable fuse to output a second feedback signal to the external control system.

[0026] Preferably, the input module also includes a second input protection circuit, the conversion module also includes a second front-stage voltage stabilization circuit, a second switch drive circuit, a second voltage transformation isolation circuit, and a second rectifier circuit, and the output module also includes a second rear-stage voltage stabilization circuit.

[0027] Preferably, the output module further includes a second voltage comparison circuit and / or a fourth voltage comparison circuit, wherein:

[0028] The second voltage comparison circuit is connected between the second post-stage voltage stabilization circuit and the mainboard of the driver, and is used to output a third feedback signal to the control chip of the driver;

[0029] The fourth voltage comparison circuit is connected to the optocoupler isolation circuit and is used for outputting a fourth feedback signal to an external control system.

[0030] The present invention also provides a safe torque off system, comprising the safe torque off circuit, a driver and an external control system as described above.

[0031] The present invention proposes a safety torque off circuit and system, which converts the voltage of the input STO signal into a preset output voltage through a conversion module, and outputs the preset output voltage to the driver board of the driver through an output module. On the one hand, due to the use of an energy transfer method, when the voltage of the input STO signal is at a low level, any component of the circuit is broken, and the circuit has no preset output voltage output, which can reliably ensure that the driver remains in a safe torque off state. On the other hand, due to the use of a hardware execution method, the voltage of the input STO signal is converted into a stable preset output voltage to control the driver to drive the motor to start or stop the motor, rather than the software instructions to determine whether the motor is allowed to run or cannot run. Therefore, when the driver software fails, the driver will not drive the motor to run because of the wrong software instructions issued by the driver software, so that when the input STO signal is for the motor to stop, the torque can be guaranteed to be shut off, prevent the motor from accidentally starting, and improve safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a structural block diagram of a safe torque off circuit of a preferred embodiment of the present invention;

[0033] Figure 2 It is a circuit structure schematic diagram of a safe torque off circuit of a preferred embodiment of the present invention;

[0034] Figure 3 It is a circuit diagram of a first input protection circuit and a first front-stage voltage stabilizing circuit in a safe torque off circuit of a preferred embodiment of the present invention;

[0035] Figure 4 is a circuit diagram of a first switch driving circuit in a safe torque off circuit of a preferred embodiment of the present invention;

[0036] Figure 5 It is a circuit diagram of a first voltage conversion isolation circuit, a first rectifier circuit and a first post-stage voltage stabilizing circuit in a preferred embodiment of the safety torque off circuit of the present invention;

[0037] Figure 6 is a circuit diagram of a first voltage comparison circuit in a safe torque off circuit of a preferred embodiment of the present invention;

[0038] Figure 7 It is a circuit diagram of a third voltage comparison circuit, an optocoupler isolation circuit and a triode switch circuit in a preferred embodiment of the safety torque off circuit of the present invention;

[0039] Figure 8 It is a circuit diagram of a second input protection circuit and a second front-stage voltage stabilizing circuit in a safe torque off circuit of a preferred embodiment of the present invention;

[0040] Fig. 9 is a circuit diagram of a second switch driving circuit in a safe torque off circuit of a preferred embodiment of the present invention;

[0041] Fig.10 It is a circuit diagram of a second voltage conversion isolation circuit, a second rectifier circuit and a second post-stage voltage stabilizing circuit in a preferred embodiment of the safety torque off circuit of the present invention;

[0042] Fig.11 is a circuit diagram of a second voltage comparison circuit in a safe torque off circuit of a preferred embodiment of the present invention;

[0043] Fig.12 It is a circuit diagram of the fourth voltage comparison circuit in the safe torque off circuit of the preferred embodiment of the present invention.

[0044] In order to make the technical solution of the present invention clearer and more understandable, it will be further described in detail below with reference to the accompanying drawings. DETAILED DESCRIPTION

[0045] It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention.

[0046] Various embodiments for implementing the present invention will now be described with reference to the accompanying drawings. In the following description, suffixes such as "module", "component" or "unit" used to represent elements are used only to facilitate the description of the present invention and have no particular meaning.

[0047] It should be further understood that the term "and / or" used in the present description and the appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0048] Reference Figure 1 , Figure 1 It is a structural block diagram of a safe torque off circuit of a preferred embodiment of the present invention.

[0049] A preferred embodiment of the present invention provides a safety torque off circuit, comprising an input module 1, a conversion module 2 and an output module 3, wherein:

[0050] The input module 1 is connected to the output module 3 via the conversion module 2;

[0051] The input module 1 is used to receive the STO signal sent by the external control system (such as an injection molding machine or a lathe system, etc.), and output the voltage of the STO signal to the conversion module 2;

[0052] The conversion module 2 is used for converting the voltage of the STO signal into a preset output voltage, and outputting the preset output voltage to the output module 3;

[0053] The output module 3 is used to output the preset output voltage to a drive board of a driver (such as a frequency converter, a servo driver, etc.) so as to control the driver to start or stop the motor through the preset output voltage.

[0054] In this embodiment, the voltage of the input STO signal is converted into a preset output voltage through the conversion module 2, and the preset output voltage is output to the driver board of the driver through the output module 3. Since the hardware execution method is adopted, the voltage of the input STO signal is converted into a stable preset output voltage to control the driver to drive the motor to start or stop the motor, rather than the software instructions to determine whether the motor is allowed to run or not. Therefore, when the driver software fails, the driver will not drive the motor to run because of the wrong software instructions issued by the driver software, so that when the input STO signal is for the motor to stop, the torque can be guaranteed to be shut off, preventing the motor from starting accidentally, and improving safety.

[0055] Specifically, refer to Figure 2 As shown, Figure 2 It is a schematic diagram of the circuit structure of the safe torque off circuit of the preferred embodiment of the present invention. The safe torque off circuit in this embodiment includes a first input protection circuit 11, a first front-stage voltage stabilizing circuit 12, a first switch driving circuit 13, a first voltage transformer isolation circuit 14, a first rectifier circuit 15, a first rear-stage voltage stabilizing circuit 16, a first voltage comparison circuit 17, a third voltage comparison circuit 31, an optocoupler isolation circuit 33, and a transistor switch circuit 34. Among them: the first front-stage voltage stabilizing circuit 12 is used to stabilize the voltage of the STO signal to obtain a stable output voltage; the first switch driving circuit 13 is used to process the stable output voltage to obtain a complementary square wave signal, and amplify the complementary square wave signal; the first voltage transformer isolation circuit 14 is used to process the amplified complementary square wave signal to obtain a square wave voltage; the first rectifier circuit 15 is used to rectify the square wave voltage to obtain a DC output voltage. The first post-stage voltage stabilizing circuit 16 is also connected to the driver board of the driver (frequency converter, servo driver, etc.) to control the opening and closing of the driver board IGBT, thereby controlling the motor to run or stop. The first voltage comparison circuit 17 is also connected to the main board of the driver to output a first feedback signal to the control chip of the driver. The transistor switch circuit 34 is also connected to the controller to output a second feedback signal to the controller, and the controller is an external control system, including an injection molding machine or a lathe system. In addition, the safety torque off circuit in this embodiment also includes a second input protection circuit 21, a second pre-stage voltage stabilizing circuit 22, a second switch drive circuit 23, a second transformer isolation circuit 24, a second rectifier circuit 25, a second post-stage voltage stabilizing circuit 26, a second voltage comparison circuit 27, and a fourth voltage comparison circuit 32.

[0056] In this embodiment, two independent STO control channels are used, and a failure in any one control channel does not affect the function of the other channel in preventing the motor from generating torque when it stops.

[0057] Reference Figure 3 As shown, Figure 3 It is a circuit diagram of a first input protection circuit and a first front-stage voltage stabilizing circuit in a safe torque off circuit of a preferred embodiment of the present invention.

[0058] The first input protection circuit 11 includes a first TVS protection device DN1 and a first diode D1. One end of the first TVS protection device DN1 is connected to the positive pole of the voltage of the STO signal, i.e., STO1+ in the figure, and the other end of the first TVS protection device DN1 is connected to the negative pole of the voltage of the STO signal, which is grounded. The anode of the first diode D1 is connected to the positive pole of the voltage of the STO signal, and the cathode of the first diode D1 is connected to the conversion module. The first TVS protection device DN1 is formed by a single bidirectional TVS tube or two unidirectional TVS tubes connected in series.

[0059] The first pre-stage voltage stabilization circuit 12 includes a first capacitor C1, a second capacitor C2 and a first voltage stabilizer U1, one end of the first capacitor C1 is connected to the cathode of the first diode D1, and the other end of the first capacitor C1 is grounded; the input end of the first voltage stabilizer U1 is connected to the cathode of the first diode D1, the ground end of the first voltage stabilizer U1 is grounded, the output end of the first voltage stabilizer U1 is grounded via the second capacitor C2, and the output end of the first voltage stabilizer U1 is also connected to the first switch drive circuit 13.

[0060] Reference Figure 4 As shown, Figure 4 It is a circuit diagram of the first switch driving circuit in the safe torque off circuit of a preferred embodiment of the present invention.

[0061] The first switch driving circuit 13 includes a first resistor R1, a fifth capacitor C5, a sixth capacitor C6, a switch signal generator U3, a first transistor Q1, a second transistor Q2, a third transistor Q3 and a fourth transistor Q4. The switch signal generator U3 includes a first adjustment pin, i.e., pin 1, a second adjustment pin, i.e., pin 2, a third adjustment pin, i.e., pin 3, input pins, i.e., pins 4, 5, 6, 12, 14, a first output pin, i.e., pin 10, and a second output pin, i.e., pin 11. The first adjustment pin is connected to the third adjustment pin via the fifth capacitor C5, the second adjustment pin is connected to the third adjustment pin via the first resistor R1, the output end of the first voltage regulator U1 is connected to the input pins, i.e., pins 4, 5, 6, and the output end of the first voltage regulator U1 is also connected to the input pins, i.e., pins 4, 5, 6, and the output end of the first voltage regulator U1 is also connected to the input pins, i.e., pins 10, 11, and the first output pin is ... The sixth capacitor C6 is grounded, and the sixth capacitor C6 is connected in parallel with the input pins such as pins 12 and 14; the first output pin is connected to the base of the first transistor Q1 and the base of the second transistor Q2, the second output pin is connected to the base of the third transistor Q3 and the base of the fourth transistor Q4, the collector of the first transistor Q1 and the collector of the third transistor Q3 are connected to the output end of the first voltage regulator U1, the emitter of the first transistor Q1 and the emitter of the second transistor Q2 are connected to the first voltage transformation isolation circuit 14, the emitter of the third transistor Q3 and the emitter of the fourth transistor Q4 are connected to the first voltage transformation isolation circuit 14, and the collector of the second transistor Q2 and the collector of the fourth transistor Q4 are grounded.

[0062] Reference Figure 5 As shown, Figure 5 It is a circuit diagram of a first voltage transformer isolation circuit, a first rectifier circuit and a first post-stage voltage stabilizing circuit in a preferred embodiment of a safe torque off circuit of the present invention.

[0063] The first transformer isolation circuit 14 includes a first isolation transformer T1, the emitter of the first transistor Q1 and the emitter of the second transistor Q2 are connected to one end of the primary end of the first isolation transformer T1, the emitter of the third transistor Q3 and the emitter of the fourth transistor Q4 are connected to the other end of the primary end of the first isolation transformer T1, and the secondary end of the first isolation transformer T1 is connected to the first rectifier circuit 15;

[0064] The first rectifier circuit 15 includes a first double diode D3 and a second double diode D4. The secondary end of the first isolation transformer T1 is connected to the anodes of the first double diode D3 and the second double diode D4 respectively. The cathodes of the first double diode D3 and the second double diode D4 are connected to the first post-stage voltage stabilization circuit 16.

[0065] The first post-stage voltage stabilization circuit 16 includes a seventh capacitor C7, an eighth capacitor C8 and a second voltage stabilizer U5, the input end of the second voltage stabilizer U5 is connected to the cathodes of the first dual diode D3 and the second dual diode D4, the input end of the second voltage stabilizer U5 is also grounded via the seventh capacitor C7, the ground end of the second voltage stabilizer U5 is grounded, the output end of the second voltage stabilizer U5 is grounded via the eighth capacitor C8, and the output end of the second voltage stabilizer U5 is also connected to the driving board of the driver to output "5V1" to the driving board of the driver to control the opening and closing of the driving board IGBT.

[0066] Reference Figure 6 As shown, Figure 6 It is a circuit diagram of a first voltage comparison circuit in a safe torque off circuit of a preferred embodiment of the present invention.

[0067] The first voltage comparison circuit 17 includes a third resistor R3, a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a nineteenth resistor R19, a thirteenth capacitor C13, a fourteenth capacitor C14 and a first comparator U7A. The output end of the second voltage regulator U5 is connected to the negative pin of the first comparator U7A via the fifth resistor R5, and the negative pin of the first comparator U7A is also grounded via the sixth resistor R6 and the fourteenth capacitor C14 in parallel. A preset reference voltage such as 5V is connected to the positive pin of the first comparator U7A via the fourth resistor R4, and the positive pin of the first comparator U7A is also grounded via the third resistor R3 and the thirteenth capacitor C13 in parallel. The output end of the first comparator U7A is connected to a preset reference voltage such as 5V via the nineteenth resistor R19, and the output end of the first comparator U7A is also connected to the main board of the driver, outputting "STO1out" to the main board of the driver to output a first feedback signal to the control chip of the driver.

[0068] Reference Figure 7 As shown, Figure 7 It is a circuit diagram of a third voltage comparison circuit, an optocoupler isolation circuit and a triode switch circuit in a preferred embodiment of the safety torque off circuit of the present invention.

[0069] The third voltage comparison circuit 31 includes: an eleventh resistor R11, a twelfth resistor R12, a thirteenth resistor R13, a fourteenth resistor R14, a seventeenth capacitor C17, an eighteenth capacitor C18 and a second comparator U7C. The output end of the second voltage regulator U5 is connected to the negative pin of the second comparator U7C via the thirteenth resistor R13, and the negative pin of the first comparator U7C is also grounded via the fourteenth resistor R14 and the eighteenth capacitor C18 in parallel. A preset reference voltage such as 5V is connected to the positive pin of the second comparator U7C via the twelfth resistor R12, and the positive pin of the second comparator U7C is also grounded via the eleventh resistor R11 and the seventeenth capacitor C17 in parallel. The output end of the second comparator U7C is also connected to the optocoupler isolation circuit 33.

[0070] The optocoupler isolation circuit 33 includes a twenty-first resistor R21, a twenty-second resistor R22, a twenty-second capacitor C22 and a photocoupler PC1. The output end of the second comparator U7C is connected to pin 2 of the photocoupler PC1 via the twenty-first resistor R21. Pin 1 of the photocoupler PC1 is connected to a preset reference voltage such as 5V. The preset reference voltage is also connected to pin 2 of the photocoupler PC1 via the twenty-second resistor R22 and the twenty-second capacitor C22 in parallel. Pins 3 and 4 of the photocoupler PC1 are connected to the transistor switch circuit 34.

[0071] The transistor switch circuit 34 includes a twenty-third resistor R23, a twenty-fourth resistor R24, a seventh diode D7, a ninth transistor Q9 and a resettable fuse F1. Pin 3 of the photoelectric coupler PC1 is grounded via the twenty-fourth resistor R24. Pin 4 of the photoelectric coupler PC1 is connected to the base of the ninth transistor Q9. Pin 4 of the photoelectric coupler is also connected to a preset power supply such as 24V via the twenty-third resistor R23. The preset power supply is connected to the emitter of the ninth transistor Q9. The preset power supply is also connected to the cathode of the seventh diode D7. The anode of the seventh diode D7 is connected to the collector of the ninth transistor Q9. The collector of the ninth transistor Q9 is also connected to the external control system via the resettable fuse F1 to output "STOFB" to the external control system to output a second feedback signal to the external control system.

[0072] Reference Figures 8 to 12As shown, the safety torque off circuit in this embodiment includes another independent STO control channel, which includes a second input protection circuit 21, a second front-stage voltage stabilizing circuit 22, a second switch driving circuit 23, a second voltage conversion isolation circuit 24, a second rectifier circuit 25, a second rear-stage voltage stabilizing circuit 26, a second voltage comparison circuit 27, and a fourth voltage comparison circuit 32, which are similar to the circuit structures of the first input protection circuit 11, the first front-stage voltage stabilizing circuit 12, the first switch driving circuit 13, the first voltage conversion isolation circuit 14, the first rectifier circuit 15, the first rear-stage voltage stabilizing circuit 16, the first voltage comparison circuit 17, and the third voltage comparison circuit 31, and are not described in detail here. It should be noted that the fourth voltage comparison circuit 32 is connected to the optical coupling isolation circuit 33, specifically, the output end of the comparator U7D in the fourth voltage comparison circuit 32 is connected to the pin 2 of the optical coupler through the twenty-first resistor R21.

[0073] The working principle of the safe torque off circuit of the preferred embodiment of the present invention is specifically described as follows:

[0074] When the external control system such as the injection molding machine or lathe system controls the STO signal to be normally turned on, there is a 24V voltage between STO1+ and STO1_GND, and the TVS tube DN1 plays an anti-EMC interference role. The 24V voltage is input to the input end of the voltage regulator U1 through the diode D1. At this time, the output end STO1_VOUT of the voltage regulator U1 has a stable voltage output, and the capacitors C1 and C2 play a filtering role. The output voltage STO1_VOUT of U1 is provided to the switch signal generator U3, and the 10th and 11th pins of U3 generate complementary square wave signals Q1+ and Q1-. Q1+ and Q1- control the transistors Q1, Q2, Q3, and Q4 to amplify the complementary square wave signals, in order to increase the current driving capability. Here, the capacitor C5 and the resistor R1 are used to adjust the switching frequency of the switch signal generator, and the capacitor C6 plays a filtering role. The amplified complementary square wave signals Q1+T and Q1-T drive the primary end of the isolation transformer T1. The secondary end of T1 generates a square wave voltage, which is rectified by the dual diodes D3 and D4 to generate a DC voltage. The DC voltage is input to the input end of the voltage regulator U5. The output end 5V1 of U5 has a stable voltage output, and the capacitors C7 and C8 play a filtering role. The stable voltage at the output end 5V1 of U5 controls the opening of the IGBT of the driver board.

[0075] On the other hand, the voltage value of 5V1 after being divided by resistors R5 and R6 is output to the A part of the voltage comparator U7, i.e., pin 4 of U7A. The voltage value of 5V voltage after being divided by resistors R3 and R4 is output to pin 5 of the A part of the voltage comparator U7. By setting the resistance values ​​of R3, R4, R5, and R6, when 5V1 has a stable voltage output, the voltage at pin 4 of the A part of the comparator is higher than the voltage at pin 5. At this time, pin 2 of the A part of the comparator outputs a low level (normal) signal to the driver control chip for feedback.

[0076] Similarly, when 5V1 has a stable voltage output, the voltage of pin 8 of the C part of comparator U7, i.e. U7C, is higher than the voltage of pin 9. At this time, pin 14 of the C part of the comparator outputs a low level (normal), turning on the optocoupler PC1 and transistor Q9. The 24V high level outputs the STOFB high level (normal) signal through Q9 and F1 to feed back the injection molding machine or lathe control system.

[0077] On the contrary, when the injection molding machine or lathe system controls the STO signal to be turned off, there is no 24V voltage between STO1+ and STO1_GND, and there is no voltage input to the input end of the voltage regulator U1. At this time, there is no voltage output at the output end STO1_VOUT of the voltage regulator U1. At this time, the switch signal generator U3 cannot work, and the 10th and 11th pins of U3 cannot generate complementary square wave signals Q1+ and Q1-. The transistors Q1, Q2, Q3, and Q4 also do not output the amplified complementary square wave signals Q1+T and Q1-T. There is no voltage signal input to the primary end of the isolation transformer T1, and there is no square wave voltage output at the secondary end of T1. The dual diodes D3 and D4 have no DC voltage output, and there is no voltage output at the output end 5V1 of the voltage regulator U5, and the driver board IGBT is turned off.

[0078] On the other hand, 5V1 has no voltage output, and the voltage at pin 4 of part A of the comparator is lower than the voltage at pin 5. At this time, pin 2 of part A of the comparator outputs a high level (off) signal and feeds it back to the driver control chip.

[0079] Similarly, when 5V1 has no voltage output, the voltage at pin 8 of the C part of the comparator U7 is lower than the voltage at pin 9. At this time, pin 14 of the C part of the comparator outputs a high level (off), turning off the optocoupler PC1, making the transistor Q9 non-conductive, and F1 outputting the STOFB low level (off) signal to feed back to the injection molding machine or lathe control system.

[0080] The safe torque off circuit in this embodiment provides a function to prevent the motor from starting unexpectedly, using two independent STO control channels and hardware execution. The failure of any one control channel does not affect the function of preventing the drive from running in the other channel. If one or both STO control inputs require the STO function, the drive will not run, even if the drive software fails and attempts to require the drive to start the motor, the drive will not run. The STO function is hardware-executed, shielding all software attempts, and the only software involvement is reporting the STO status to prompt the user.

[0081] Moreover, the source of the output voltage of the safety torque off circuit in this embodiment is essentially the voltage of the STO signal. The energy transfer method is adopted to convert the voltage of the input STO signal into a stable output voltage through this circuit to control the opening of the driver board IGBT. When the input STO voltage is cut off, the output voltage converted by this circuit will also be reduced to 0V. When the input STO voltage is cut off, any component of this circuit fails, which does not affect the output voltage converted by this circuit to 0V, and controls the driver board IGBT to turn off, which can reliably ensure torque shutdown and has high safety.

[0082] The present invention further proposes a safe torque off system, which includes the above-mentioned safe torque off circuit, a driver and an external control system. The working principle of the system is as described above and will not be repeated here.

[0083] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. Any equivalent structure or process transformation made by using the contents of the present invention specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A safety torque off circuit, characterized in that: It includes input module, conversion module and output module, among which: The input module is connected to the output module via the conversion module; The input module is used to receive the STO signal sent by the external control system and output the voltage of the STO signal to the conversion module; The conversion module is used to convert the voltage of the STO signal into a preset output voltage, and output the preset output voltage to the output module; The output module is used to output the preset output voltage to the driver board of the driver, so as to control the driver to start or stop the motor through the preset output voltage; The input module includes a first input protection circuit, the first input protection circuit includes a first TVS protection device and a first diode, one end of the first TVS protection device is connected to the positive electrode of the voltage of the STO signal, the other end of the first TVS protection device is connected to the negative electrode of the voltage of the STO signal, and the negative electrode of the voltage of the STO signal is grounded; the anode of the first diode is connected to the positive electrode of the voltage of the STO signal, and the cathode of the first diode is connected to the conversion module; The conversion module includes a first front-stage voltage stabilization circuit, a first switch driving circuit, a first voltage transformation isolation circuit, and a first rectifier circuit, wherein: The first front-stage voltage stabilizing circuit is used to stabilize the voltage of the STO signal to obtain a stable output voltage; The first switch driving circuit is used to process the stable output voltage to obtain a complementary square wave signal, and amplify the complementary square wave signal; The first voltage conversion isolation circuit is used to process the amplified complementary square wave signal to obtain a square wave voltage isolated from the input STO signal; The first rectifier circuit is used to rectify the square wave voltage to obtain a DC output voltage; The first pre-stage voltage stabilization circuit includes a first capacitor, a second capacitor, and a first voltage stabilizer, one end of the first capacitor is connected to the cathode of the first diode, and the other end of the first capacitor is grounded; the input end of the first voltage stabilizer is connected to the cathode of the first diode, the ground end of the first voltage stabilizer is grounded, the output end of the first voltage stabilizer is grounded via the second capacitor, and the output end of the first voltage stabilizer is also connected to the first switch driving circuit; The first switch driving circuit includes a first resistor, a fifth capacitor, a sixth capacitor, a switch signal generator, a first transistor, a second transistor, a third transistor and a fourth transistor. The switch signal generator includes a first adjustment pin, a second adjustment pin, a third adjustment pin, an input pin, a first output pin and a second output pin. The first adjustment pin is connected to the third adjustment pin via the fifth capacitor, the second adjustment pin is connected to the third adjustment pin via the first resistor, the output end of the first voltage regulator is connected to the input pin, the output end of the first voltage regulator is also grounded via the sixth capacitor, and the sixth The capacitor is connected in parallel with the input pin; the first output pin is connected with the base of the first transistor and the base of the second transistor, the second output pin is connected with the base of the third transistor and the base of the fourth transistor, the collector of the first transistor and the collector of the third transistor are connected to the output end of the voltage regulator, the emitter of the first transistor and the emitter of the second transistor are connected to the first voltage conversion isolation circuit, the emitter of the third transistor and the emitter of the fourth transistor are connected to the first voltage conversion isolation circuit, and the collector of the second transistor and the collector of the fourth transistor are grounded; The first transformer isolation circuit includes an isolation transformer, the emitter of the first transistor and the emitter of the second transistor are connected to one end of the primary end of the isolation transformer, the emitter of the third transistor and the emitter of the fourth transistor are connected to the other end of the primary end of the isolation transformer, and the secondary end of the isolation transformer is connected to the first rectifier circuit; The first rectifier circuit includes a first double diode and a second double diode. The secondary end of the isolation transformer is connected to the anodes of the first double diode and the second double diode respectively. The cathodes of the first double diode and the second double diode are connected to the output module.

2. The safe torque off circuit according to claim 1, characterized in that: The output module includes a first post-stage voltage stabilization circuit, which includes a seventh capacitor, an eighth capacitor and a second voltage regulator. The input end of the second voltage regulator is connected to the cathodes of the first double diode and the second double diode. The input end of the second voltage regulator is also grounded via the seventh capacitor. The grounding end of the second voltage regulator is grounded. The output end of the second voltage regulator is grounded via the eighth capacitor. The output end of the second voltage regulator is also connected to the driving board of the driver to control the opening and closing of the driving board IGBT.

3. The safe torque off circuit according to claim 2, characterized in that: The output module also includes a first voltage comparison circuit, which includes: a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a nineteenth resistor, a thirteenth capacitor, a fourteenth capacitor and a first comparator. The output end of the second voltage regulator is connected to the negative pin of the first comparator via the fifth resistor, and the negative pin of the first comparator is also grounded via the sixth resistor and the fourteenth capacitor in parallel. The preset reference voltage is connected to the positive pin of the first comparator via the fourth resistor, and the positive pin of the first comparator is also grounded via the third resistor and the thirteenth capacitor in parallel. The output end of the first comparator is connected to the preset reference voltage via the nineteenth resistor, and the output end of the first comparator is also connected to the mainboard of the driver to output a first feedback signal to the control chip of the driver.

4. The safe torque off circuit according to claim 3, characterized in that: The output module further includes a third voltage comparison circuit, an optocoupler isolation circuit, and a triode switch circuit, wherein: The third voltage comparison circuit includes: an eleventh resistor, a twelfth resistor, a thirteenth resistor, a fourteenth resistor, a seventeenth capacitor, an eighteenth capacitor and a second comparator, the output end of the second voltage regulator is connected to the negative pin of the second comparator via the thirteenth resistor, the negative pin of the first comparator is also grounded via the fourteenth resistor and the eighteenth capacitor connected in parallel, the preset reference voltage is connected to the positive pin of the second comparator via the twelfth resistor, the positive pin of the second comparator is also grounded via the eleventh resistor and the seventeenth capacitor connected in parallel, and the output end of the second comparator is also connected to the optocoupler isolation circuit; The optical coupling isolation circuit includes a twenty-first resistor, a twenty-second resistor, a twenty-second capacitor and a photocoupler, the output end of the second comparator is connected to pin 2 of the photocoupler via the twenty-first resistor, pin 1 of the photocoupler is connected to a preset reference voltage, the preset reference voltage is further connected to pin 2 of the photocoupler via the twenty-second resistor and the twenty-second capacitor connected in parallel, and pins 3 and 4 of the photocoupler are connected to the transistor switch circuit; The transistor switch circuit includes a twenty-third resistor, a twenty-fourth resistor, a seventh diode, a ninth transistor and a resettable fuse. Pin 3 of the photocoupler is grounded via the twenty-fourth resistor, pin 4 of the photocoupler is connected to the base of the ninth transistor, pin 4 of the photocoupler is also connected to a preset power supply via the twenty-third resistor, the preset power supply is connected to the emitter of the ninth transistor, the preset power supply is also connected to the cathode of the seventh diode, the anode of the seventh diode is connected to the collector of the ninth transistor, and the collector of the ninth transistor is also connected to the external control system via the resettable fuse to output a second feedback signal to the external control system.

5. The safe torque off circuit according to claim 4, characterized in that: The input module also includes a second input protection circuit, the conversion module also includes a second front-stage voltage stabilization circuit, a second switch drive circuit, a second voltage transformation isolation circuit, and a second rectifier circuit, and the output module also includes a second rear-stage voltage stabilization circuit.

6. The safe torque off circuit according to claim 5, characterized in that: The output module further includes a second voltage comparison circuit and / or a fourth voltage comparison circuit, wherein: The second voltage comparison circuit is connected between the second post-stage voltage stabilization circuit and the mainboard of the driver, and is used to output a third feedback signal to the control chip of the driver; The fourth voltage comparison circuit is connected to the optocoupler isolation circuit and is used for outputting a fourth feedback signal to an external control system.

7. A safety torque off system, characterized in that: The invention comprises a safety torque off circuit, a driver and an external control system according to any one of claims 1 to 6.

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