Motor speed regulation protection circuit of pulverizer

Abstract

The utility model discloses a motor speed regulation protection circuit of a pulverizer, which relates to the technical field of pulverizer motors, and comprises a power supply module used for electric energy conversion and power supply control; the motor driving module is used for oscillating and controlling the rotating speed of the crusher motor module; the crusher motor module is used for controlling a crusher motor to rotate; the over-current detection module is used for carrying out current sampling, signal processing and over-current detection on the crusher motor module; the degree detection module is used for detecting the overcurrent degree during overcurrent; the speed reduction control module is used for adjusting the duty ratio of the signal output by the motor driving module in a delayed manner; and the protection module is used for performing over-current protection control after speed reduction. The motor speed regulation protection circuit of the pulverizer can automatically reduce the rotating speed of the motor module of the pulverizer, reduce the discharging amount and improve the working efficiency of the pulverizer when the overcurrent degree of the motor of the pulverizer is low, and can perform power-off protection and improve the safety of the circuit if the overcurrent degree is increased.

Description

TECHNICAL FIELD

[0001] The utility model relates to a motor speed regulation protection circuit of a pulverizer, and particularly relates to a motor speed regulation protection circuit of a pulverizer. BACKGROUND

[0002] The pulverizer is a mechanical device for pulverizing solid raw materials of large size to a required size. The motor, as the main structure of the pulverizer, is responsible for driving and pulverizing the materials. The motor speed regulation protection circuit of the pulverizer in the prior art generally consists of a NE555 speed regulation circuit, a motor circuit and an overcurrent detection circuit. The speed of the motor circuit can be adjusted through the NE555 speed regulation circuit, and the motor circuit is controlled to stop working when the motor circuit is overcurrent. However, when the discharge of the discharge port of the pulverizer is slow, the motor of the pulverizer is also prone to locked-rotor condition, which in turn leads to frequent shutdown of the motor of the pulverizer, thereby reducing the working efficiency of the pulverizer. Therefore, there is room for improvement. SUMMARY

[0003] The utility model embodiment provides a motor speed regulation protection circuit of a pulverizer to solve the problems in the background art.

[0004] To achieve the above object, the utility model provides the following technical scheme:

[0005] A motor speed regulation protection circuit of a pulverizer, comprising: a power supply module, a motor drive module, a pulverizer motor module, an overcurrent detection module, a degree detection module, a speed reduction control module and a protection module;

[0006] The power supply module is connected with the motor drive module, the protection module and the degree detection module, is used for carrying out step-down and rectifier filter processing to the input alternating current and outputting first electric energy, carrying out voltage stabilizing processing to the first electric energy and outputting second electric energy, transmitting the second electric energy to the motor drive module, stopping the transmission of the second electric energy when receiving the second protection signal output by the protection module or the first protection signal output by the degree detection module;

[0007] The motor drive module is connected with the speed reduction control module and the pulverizer motor module, is used for oscillating and outputting a first drive signal when receiving the second electric energy, reducing the frequency of the first drive signal and reducing the speed of the pulverizer motor module when receiving the first control signal output by the speed reduction control module;

[0008] The pulverizer motor module is connected with the power supply module, is used for receiving the first electric energy and controlling the rotation of the pulverizer motor when receiving the first drive signal;

[0009] The overcurrent detection module is connected with the grinder motor module, and is used for sampling the current of the grinder motor module, amplifying and filtering the sampled signal, and converting the signal into a voltage signal; when the voltage signal is greater than a set overcurrent threshold, a second control signal is outputted;

[0010] The degree detection module is connected with the overcurrent detection module, and is used for subtracting the voltage signal from the overcurrent threshold and outputting a first difference signal; when the first difference signal is greater than a set overcurrent difference threshold, a first protection signal is outputted; and when the first difference signal is less than the set overcurrent difference threshold, a third control signal is outputted.

[0011] The speed reduction control module is connected with the overcurrent detection module and the degree detection module, and is used for storing the second control signal and outputting the first control signal with a time delay when the third control signal is received.

[0012] The protection module is connected with the overcurrent detection module and the speed reduction control module, and is used for outputting the second protection signal when the first control signal and the second control signal are received.

[0013] As a further scheme of the utility model: the power module includes a power interface, a first transformer, a first rectifier, a first capacitor, a first voltage stabilizer, a second capacitor, a first resistor, a first power tube and a first switch tube;

[0014] Preferably, the first end and the second end of the power interface are connected with the first end and the second end of the primary side of the first transformer respectively, the first end and the second end of the secondary side of the first transformer are connected with the first end and the second end of the first rectifier respectively, the third end of the first rectifier is connected with the first end of the first voltage stabilizer and the fourth end of the first rectifier, the second end of the first voltage stabilizer, one end of the second capacitor, the emitter of the first switch tube and the ground end through the first capacitor, the third end of the first voltage stabilizer is connected with the other end of the second capacitor and the drain of the first power tube and is connected with the gate of the first power tube and the collector of the first switch tube through the first resistor, the base of the first switch tube is connected with the protection module and the degree detection module, and the source of the first power tube is connected with the motor driving module.

[0015] As a further scheme of the utility model: the motor driving module includes a fifth resistor, a first potentiometer, a fourth resistor, a second resistor, a sixth resistor, a third capacitor, a first diode, a second switch tube, a first driver and a fourth capacitor;

[0016] Preferably, the fourth end and the eighth end of the first driver are connected to the source of the first power tube, and the seventh end of the first driver, the cathode of the first diode, one end of the first potentiometer and the wiper end of the first potentiometer are connected through the fifth resistor, the other end of the first potentiometer is connected to the collector of the second switch tube, and the other end of the second resistor, the other end of the sixth resistor, one end of the third capacitor, the second end and the sixth end of the first driver are connected through the fourth resistor, the other end of the sixth resistor is connected to the anode of the first diode, the emitter of the second switch tube is connected to the other end of the second resistor, the base of the second switch tube is connected to the speed reduction control module, the fifth end of the first driver is connected to the first end of the first driver and the other end of the third capacitor through the fourth capacitor, and the third end of the first driver is connected to the grinder motor module.

[0017] As a further scheme of the utility model: the grinder motor module comprises a second power tube, a seventh resistor and a first motor;

[0018] Preferably, the drain of the second power tube is connected to the third end of the first rectifier, the source of the second power tube is connected to the first end of the first motor, the second end of the first motor is connected to the overcurrent detection module, and the gate of the second power tube is connected to the third end of the first driver through the seventh resistor.

[0019] As a further scheme of the utility model: the overcurrent detection module comprises an eighth resistor, a signal processing device, an overcurrent threshold device and a first comparator;

[0020] Preferably, one end of the eighth resistor is connected to the first input end of the signal processing device and the second end of the first motor, the other end of the eighth resistor is connected to the second input end of the signal processing device and the ground end, the output end of the signal processing device is connected to the non-inverting end of the first comparator, the inverting end of the first comparator is connected to the overcurrent threshold device, and the output end of the first comparator is connected to the speed reduction control module and the protection module.

[0021] As a further scheme of the utility model: the speed reduction control module comprises a fourth diode, a fifth capacitor and a first logic chip; and the protection module comprises a second logic chip;

[0022] Preferably, the anode of the fourth diode is connected to the output end of the first comparator and the B end of the second logic chip, the A end of the first logic chip is connected to the cathode of the fourth diode and grounded through the fifth capacitor, the Y end of the first logic chip is connected to the A end of the second logic chip and the base of the second switch tube, and the Y end of the second logic chip is connected to the base of the first switch tube.

[0023] As a further scheme of the utility model: the degree detection module comprises a ninth resistor, a tenth resistor, an eleventh resistor, a twelfth resistor, a first operational amplifier, a third resistor, a second diode, a third diode and a first inverter;

[0024] Preferably, the non-inverting terminal of the first operational amplifier is connected to one end of the ninth resistor and to the ground through the eleventh resistor, the other end of the ninth resistor is connected to the output terminal of the signal processing device, the inverting terminal of the first operational amplifier is connected to one end of the twelfth resistor and to the overcurrent threshold device through the tenth resistor, the output terminal of the first operational amplifier is connected to the other end of the twelfth resistor and to the cathode of the second diode through the third resistor, the anode of the second diode is connected to the anode of the third diode and the input terminal of the first inverter, the output terminal of the first inverter is connected to the B terminal of the first logic chip, and the cathode of the third diode is connected to the base of the first switch tube.

[0025] Compared with the prior art, the motor speed regulation protection circuit of the pulverizer has the beneficial effects that: the motor driving module controls the pulverizer motor module to start rotating, the overcurrent detection module detects the overcurrent degree of the pulverizer motor module, the overcurrent degree detection module detects the overcurrent degree, and when the overcurrent degree does not exceed the overcurrent difference threshold, the speed reduction control module reduces the duty cycle of the signal output by the motor driving module, thereby reducing the speed of the pulverizer motor module, reducing the discharge amount, and improving the working efficiency of the pulverizer; if the overcurrent degree is greater than the overcurrent difference threshold or the overcurrent still occurs after the speed reduction, the power supply module is controlled to be powered off for protection, thereby improving the safety of the circuit. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the description of the embodiments of the present application. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor.

[0027] Figure 1 A principle block diagram of the motor speed regulation protection circuit of the pulverizer is provided for the embodiments of the present application.

[0028] Figure 2 A circuit diagram of the motor speed regulation protection circuit of the pulverizer is provided for the embodiments of the present application.

[0029] Figure 3 A connection circuit diagram of the degree detection module is provided for the embodiments of the present application. DETAILED DESCRIPTION

[0030] The technical solutions of the embodiments of the present application will be described clearly and completely in the following with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some embodiments of the present application, not all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0031] In one embodiment, please refer to Figure 1 A motor speed regulation protection circuit of a shredder, comprising: a power module 1, a motor drive module 2, a shredder motor module 3, an overcurrent detection module 4, a degree detection module 5, a speed reduction control module 6 and a protection module 7;

[0032] Specifically, the power module 1 is connected with the motor drive module 2, the protection module 7 and the degree detection module 5, used for performing step-down and rectification filtering processing on the input alternating current energy and outputting first electrical energy, performing voltage stabilization processing on the first electrical energy and outputting second electrical energy, transmitting the second electrical energy to the motor drive module 2, and stopping the transmission of the second electrical energy when receiving the second protection signal output by the protection module 7 or the first protection signal output by the degree detection module 5;

[0033] The motor drive module 2 is connected with the speed reduction control module 6 and the shredder motor module 3, used for oscillating and outputting a first drive signal when receiving the second electrical energy, and reducing the frequency of the first drive signal and the rotating speed of the shredder motor module 3 when receiving the first control signal output by the speed reduction control module 6;

[0034] The shredder motor module 3 is connected with the power module 1, used for receiving the first electrical energy and controlling the rotation of the shredder motor when receiving the first drive signal;

[0035] The overcurrent detection module 4 is connected with the shredder motor module 3, used for sampling the current of the shredder motor module 3, amplifying and filtering the sampled signal and converting it into a voltage signal, and outputting a second control signal when the voltage signal is greater than a set overcurrent threshold value;

[0036] The degree detection module 5 is connected with the overcurrent detection module 4, used for performing subtraction processing on the voltage signal and the overcurrent threshold value and outputting a first difference signal, outputting a first protection signal when the first difference signal is greater than a set overcurrent difference threshold value, and outputting a third control signal when the first difference signal is less than the set overcurrent difference threshold value;

[0037] The speed reduction control module 6 is connected with the overcurrent detection module 4 and the degree detection module 5, used for storing the second control signal and outputting the first control signal with a time delay when receiving the third control signal;

[0038] The protection module 7 is connected with the overcurrent detection module 4 and the speed reduction control module 6, used for outputting a second protection signal when receiving the first control signal and the second control signal.

[0039] In specific embodiments, the power module 1 described above can adopt a power circuit composed of a power interface, a transformer, a rectifier, a voltage stabilizer, a field effect tube, etc., can be connected to alternating current energy and perform voltage transformation, rectification filtering, voltage stabilization and power transmission control on the alternating current energy; the motor drive module 2 described above can adopt a motor drive circuit composed of a 555 integrated circuit, a diode, a triode, etc., to perform oscillation and provide a first drive signal, and adjust the duty cycle of the first drive signal, thereby realizing speed regulation of the grinder motor module 3; the grinder motor module 3 described above can adopt a grinder motor circuit composed of a resistor, a field effect tube, and a grinder motor, to control the speed of the grinder motor; the overcurrent detection module 4 described above can adopt an overcurrent detection circuit composed of a resistor, a signal processing device, a comparator, etc., which can sample the current of the grinder motor module 3, amplify and filter the signal, and convert the current voltage, and compare the processed signal with the size of the set overcurrent threshold; the degree detection module 5 described above can adopt a degree detection circuit composed of a resistor, an operational amplifier, a diode, etc., which can calculate the difference between the signal output by the overcurrent detection module 4 and the overcurrent threshold, then judge the overcurrent degree, and detect whether the overcurrent degree exceeds the overcurrent difference threshold, if not, it means that the overcurrent degree is not serious, and speed reduction control can be performed; the speed reduction control module 6 described above can adopt a speed reduction control circuit composed of a logic chip, a capacitor and a diode, which can perform logic calculation and delay control the duty cycle of the signal output by the motor drive module 2 when the overcurrent degree does not exceed the overcurrent difference threshold; the protection module 7 described above can adopt a protection circuit composed of a logic chip, which can perform logic calculation and detect whether overcurrent occurs during speed reduction, and control the power module 1 to be powered off when overcurrent occurs.

[0040] In another embodiment, please refer to Figure 1 , Figure 2 and Figure 3 , the power module 1 includes a power interface, a first transformer B1, a first rectifier T1, a first capacitor C1, a first voltage stabilizer IC1, a second capacitor C2, a first resistor R1, a first power tube Q1 and a first switch tube V1;

[0041] Specifically, the first end and the second end of the power interface are connected to the first end and the second end of the primary side of the first transformer B1 respectively, the first end and the second end of the secondary side of the first transformer B1 are connected to the first end and the second end of the first rectifier T1 respectively, the third end of the first rectifier T1 is connected to the first end of the first voltage stabilizer IC1, and the fourth end of the first rectifier T1, the second end of the first voltage stabilizer IC1, one end of the second capacitor C2, the emitter of the first switch tube V1 and the ground end are connected through the first capacitor C1, the third end of the first voltage stabilizer IC1 is connected to the other end of the second capacitor C2 and the drain of the first power tube Q1, and the gate of the first power tube Q1 and the collector of the first switch tube V1 are connected through the first resistor R1, the base of the first switch tube V1 is connected to the protection module 7 and the degree detection module 5, and the source of the first power tube Q1 is connected to the motor driving module 2.

[0042] In specific embodiments, the first voltage stabilizer IC1 can be selected as a 7809 voltage stabilizer, the first power tube Q1 can be selected as an N-channel field effect tube, and the first switch tube V1 can be selected as an NPN type triode.

[0043] Further, the motor driving module 2 includes a fifth resistor R5, a first potentiometer RP1, a fourth resistor R4, a second resistor R2, a sixth resistor R6, a third capacitor C3, a first diode D1, a second switch tube D2, a first driver IC2 and a fourth capacitor C4.

[0044] Specifically, the fourth end and the eighth end of the first driver IC2 are both connected to the source of the first power tube Q1 and connected to the seventh end of the first driver IC2, the cathode of the first diode D1, one end of the first potentiometer RP1 and the wiper end of the first potentiometer RP1 through the fifth resistor R5, the other end of the first potentiometer RP1 is connected to the collector of the second switch tube D2 and connected to one end of the second resistor R2, one end of the sixth resistor R6, one end of the third capacitor C3, the second end and the sixth end of the first driver IC2 through the fourth resistor R4, the other end of the sixth resistor R6 is connected to the anode of the first diode D1, the emitter of the second switch tube D2 is connected to the other end of the second resistor R2, the base of the second switch tube D2 is connected to the speed reduction control module 6, the fifth end of the first driver IC2 is connected to the first end of the first driver IC2 and the other end of the third capacitor C3 through the fourth capacitor C4, and the third end of the first driver IC2 is connected to the mill motor module 3.

[0045] In specific embodiments, the first driver IC2 can be selected as an NE555 chip, the second switch tube D2 can be selected as an NPN type triode, and the first potentiometer RP1 or the second switch tube D2 and the second resistor R2 can adjust the duty cycle of the first driving signal output from the third end of the first driver IC2.

[0046] Further, the grinder motor module 3 comprises a second power tube Q2, a seventh resistor R7 and a first motor M1.

[0047] Specifically, the drain of the second power tube Q2 is connected to the third terminal of the first rectifier T1, the source of the second power tube Q2 is connected to the first terminal of the first motor M1, the second terminal of the first motor M1 is connected to the overcurrent detection module 4, and the gate of the second power tube Q2 is connected to the third terminal of the first driver IC2 through the seventh resistor R7.

[0048] In specific embodiments, the second power tube Q2 can be an N-channel field effect tube, and the first motor M1 is a grinder motor.

[0049] Further, the overcurrent detection module 4 comprises an eighth resistor R8, a signal processing device, an overcurrent threshold device and a first comparator A1.

[0050] Specifically, one end of the eighth resistor R8 is connected to the first input terminal of the signal processing device and the second terminal of the first motor M1, the other end of the eighth resistor R8 is connected to the second input terminal of the signal processing device and the ground terminal, the output terminal of the signal processing device is connected to the non-inverting terminal of the first comparator A1, the inverting terminal of the first comparator A1 is connected to the overcurrent threshold device, and the output terminal of the first comparator A1 is connected to the speed reduction control module 6 and the protection module 7.

[0051] In specific embodiments, the eighth resistor R8 performs current sampling, the signal processing device can be composed of a resistor, an operational amplifier and a capacitor, amplifies and filters the input signal and converts the current signal into a voltage signal, the first comparator A1 can be an LM358 comparator, and the overcurrent threshold device can be composed of a resistor and a reference power supply to provide an overcurrent threshold.

[0052] Further, the speed reduction control module 6 comprises a fourth diode D4, a fifth capacitor C5 and a first logic chip J1, and the protection module 7 comprises a second logic chip J2.

[0053] Specifically, the anode of the fourth diode D4 is connected to the output terminal of the first comparator A1 and the B terminal of the second logic chip J2, the A terminal of the first logic chip J1 is connected to the cathode of the fourth diode D4 and grounded through the fifth capacitor C5, the Y terminal of the first logic chip J1 is connected to the A terminal of the second logic chip J2 and the base of the second switch tube D2, and the Y terminal of the second logic chip J2 is connected to the base of the first switch tube V1.

[0054] In specific embodiments, the first logic chip J1 and the second logic chip J2 can be AND gate chips, and the fifth capacitor C5 stores electrical energy to control the A terminal of the first logic chip J1 to be in a high level state.

[0055] Further, the degree detecting module 5 comprises a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11, a twelfth resistor R12, a first operational amplifier OP1, a third resistor R3, a second diode D2, a third diode D3 and a first inverter INV1;

[0056] Specifically, the non-inverting terminal of the first operational amplifier OP1 is connected to one end of the ninth resistor R9 and grounded through the eleventh resistor R11, the other end of the ninth resistor R9 is connected to the output terminal of the signal processing device, the inverting terminal of the first operational amplifier OP1 is connected to one end of the twelfth resistor R12 and connected to the overcurrent threshold device through the tenth resistor R10, the output terminal of the first operational amplifier OP1 is connected to the other end of the twelfth resistor R12 and connected to the cathode of the second diode D2 through the third resistor R3, the anode of the second diode D2 is connected to the anode of the third diode D3 and the input terminal of the first inverter INV1, the output terminal of the first inverter INV1 is connected to the B terminal of the first logic chip J1, and the cathode of the third diode D3 is connected to the base of the first switch tube V1.

[0057] In specific embodiments, the first operational amplifier OP1 can be OP07 operational amplifier, which cooperates with the ninth resistor R9, the tenth resistor R10, the eleventh resistor R11 and the twelfth resistor R12 to perform subtraction processing and then calculate the overcurrent degree; the third resistor R3 and the second diode D2 set the overcurrent difference threshold.

[0058] The motor speed regulation protection circuit of the pulverizer of the embodiment is connected with AC power through a power interface, a first transformer B1, a first rectifier T1 and a first capacitor C1 are used for voltage reduction, rectification and filtering, and a first electric energy is output, the first electric energy is stabilized by a second capacitor C2 and a first voltage stabilizer IC1, a second electric energy is output, the second electric energy is transmitted to a first driver IC2 through a first power tube Q1, the first driver IC2 cooperates with a fifth resistor R5, a first potentiometer RP1, a first diode D1, a sixth resistor R6, a fourth diode D4, a third capacitor C3 and a fourth capacitor C4 to oscillate and output a first drive signal, the first drive signal drives a second power tube Q2 to be turned on, so that the second electric energy is transmitted to a first motor M1 through the second power tube Q2, in order to avoid the situation that the first motor M1 is blocked due to the blockage of the discharge port and the like, an eighth resistor R8 is used for current sampling of the first motor M1, a signal processing device is used for signal amplification filtering and signal conversion processing, and a voltage signal is output, when the voltage signal is greater than an overcurrent threshold, a first comparator A1 outputs a second control signal, and a first operational amplifier OP1, a ninth resistor R9, a tenth resistor R10, an eleventh resistor R11 and a twelfth resistor R12 are used for subtraction processing of the voltage signal and the overcurrent threshold to obtain a first difference signal, when the first difference signal is lower than an overcurrent difference threshold set by a third resistor R3 and a second diode D2, a first switch tube V1 is turned on, a second resistor R2 and a fourth resistor R4 are connected in parallel, the duty cycle of the first drive signal is reduced, the rotating speed of the first motor M1 is reduced, meanwhile, a fifth capacitor C5 is used for delay and keeping the low-speed rotation of the first motor M1, and the discharge rate of the discharge port is reduced, if the rotating speed of the first motor M1 is reduced and overcurrent is still detected, a second logic chip J2 directly controls the first switch tube V1 to be turned on, and the first power tube Q1 is powered off, or when the first difference signal is greater than the set overcurrent difference threshold, the first switch tube V1 is also directly controlled to be turned on, and the first power tube Q1 is powered off.

[0059] It is apparent for those skilled in the art that the present application is not limited to the details of the foregoing exemplary embodiments, and the present application can be implemented in other concrete forms without departing from the spirit or essential characteristics of the present application. Therefore, the foregoing embodiments should be considered in all aspects as illustrative and not restrictive, and the scope of the present application is defined by the appended claims rather than the foregoing description, and it is intended to embrace all changes falling within the meaning and range of equivalents of the elements of the claims. Any reference signs in the claims should not be regarded as limiting the claims to which they belong.

[0060] Furthermore, it should be understood that although the specification is described in terms of embodiments, not every embodiment includes every feature described. The specification can include implicit combinations of explicitly mentioned features and / or explicit combinations of implicitely mentioned features. Each embodiment depends on the explicit combinations of features and / or the implicit combinations of features made specifically within that embodiment, and each such embodiment can be combined with every other such embodiment to create further embodiments.

Claims

1. A motor speed regulation protection circuit of a pulverizer, characterized in that, the motor speed regulation protection circuit of the pulverizer comprises a power supply module, a motor drive module, a pulverizer motor module, an overcurrent detection module, a degree detection module, a speed reduction control module and a protection module; the power supply module is connected with the motor drive module, the protection module and the degree detection module, is used for performing step-down and rectification filtering processing on the input alternating current energy and outputting first electric energy, performing voltage stabilization processing on the first electric energy and outputting second electric energy, transmitting the second electric energy to the motor drive module, and stopping the transmission of the second electric energy when receiving the second protection signal output by the protection module or the first protection signal output by the degree detection module; the motor drive module is connected with the speed reduction control module and the pulverizer motor module, is used for oscillating and outputting a first drive signal when receiving the second electric energy, and reducing the frequency of the first drive signal and the rotating speed of the pulverizer motor module when receiving the first control signal output by the speed reduction control module; the pulverizer motor module is connected with the power supply module, is used for receiving the first electric energy and controlling the rotation of the pulverizer motor when receiving the first drive signal; the overcurrent detection module is connected with the pulverizer motor module, is used for sampling the current of the pulverizer motor module, amplifying and filtering the sampled signal and converting it into a voltage signal, and outputting a second control signal when the voltage signal is greater than a set overcurrent threshold; the degree detection module is connected with the overcurrent detection module, is used for performing subtraction processing on the voltage signal and the overcurrent threshold and outputting a first difference signal, outputting a first protection signal when the first difference signal is greater than a set overcurrent difference threshold, and outputting a third control signal when the first difference signal is less than the set overcurrent difference threshold; the speed reduction control module is connected with the overcurrent detection module and the degree detection module, is used for storing the second control signal and outputting the first control signal after a delay when receiving the third control signal; the protection module is connected with the overcurrent detection module and the speed reduction control module, is used for outputting a second protection signal when receiving the first control signal and the second control signal.

2. A motor speed regulation protection circuit for a shredder according to claim 1, wherein the power supply module comprises a power supply interface, a first transformer, a first rectifier, a first capacitor, a first voltage stabilizer, a second capacitor, a first resistor, a first power tube and a first switch tube; the first end and the second end of the power supply interface are connected with the first end and the second end of the primary side of the first transformer, the first end and the second end of the secondary side of the first transformer are connected with the first end and the second end of the first rectifier, the third end of the first rectifier is connected with the first end of the first voltage stabilizer and the fourth end of the first rectifier, the second end of the first voltage stabilizer, one end of the second capacitor, the emitter of the first switch tube and the ground end through the first capacitor, the third end of the first voltage stabilizer is connected with the other end of the second capacitor and the drain of the first power tube and is connected with the gate of the first power tube and the collector of the first switch tube through the first resistor, the base of the first switch tube is connected with the protection module and the degree detection module, and the source of the first power tube is connected with the motor drive module.

3. A motor speed regulation protection circuit for a shredder according to claim 2, wherein The motor driving module comprises a fifth resistor, a first potentiometer, a fourth resistor, a second resistor, a sixth resistor, a third capacitor, a first diode, a second switch tube, a first driver and a fourth capacitor; The fourth end and the eighth end of the first driver are connected to the source of the first power tube, and the seventh end of the first driver, the cathode of the first diode, one end of the first potentiometer and the wiper end of the first potentiometer are connected through the fifth resistor; the other end of the first potentiometer is connected to the collector of the second switch tube, and the other end of the second resistor, the other end of the sixth resistor, the other end of the third capacitor, the second end and the sixth end of the first driver are connected through the fourth resistor; the other end of the sixth resistor is connected to the anode of the first diode; the emitter of the second switch tube is connected to the other end of the second resistor; the base of the second switch tube is connected to the speed reduction control module; the fifth end of the first driver is connected to the first end of the first driver and the other end of the third capacitor through the fourth capacitor; and the third end of the first driver is connected to the grinder motor module.

4. A motor speed regulation protection circuit for a shredder according to claim 3, wherein The grinder motor module comprises a second power tube, a seventh resistor and a first motor; The drain of the second power tube is connected to the third end of the first rectifier; the source of the second power tube is connected to the first end of the first motor; the second end of the first motor is connected to the overcurrent detection module; and the gate of the second power tube is connected to the third end of the first driver through the seventh resistor.

5. A motor speed control protection circuit for a shredder according to claim 4, wherein The overcurrent detection module comprises an eighth resistor, a signal processing device, an overcurrent threshold device and a first comparator; One end of the eighth resistor is connected to the first input end of the signal processing device and the second end of the first motor; the other end of the eighth resistor is connected to the second input end of the signal processing device and the ground end; the output end of the signal processing device is connected to the non-inverting end of the first comparator; the inverting end of the first comparator is connected to the overcurrent threshold device; and the output end of the first comparator is connected to the speed reduction control module and the protection module.

6. A motor speed control protection circuit for a shredder as defined in claim 5, wherein The speed reduction control module comprises a fourth diode, a fifth capacitor and a first logic chip; and the protection module comprises a second logic chip. The anode of the fourth diode is connected to the output end of the first comparator and the B end of the second logic chip; the A end of the first logic chip is connected to the cathode of the fourth diode and grounded through the fifth capacitor; the Y end of the first logic chip is connected to the A end of the second logic chip and the base of the second switch tube; and the Y end of the second logic chip is connected to the base of the first switch tube.

7. A motor speed control protection circuit for a shredder according to claim 6, wherein The degree detection module comprises a ninth resistor, a tenth resistor, an eleventh resistor, a twelfth resistor, a first operational amplifier, a third resistor, a second diode, a third diode and a first inverter; The non-inverting end of the first operational amplifier is connected to one end of the ninth resistor and grounded through the eleventh resistor; the other end of the ninth resistor is connected to the output end of the signal processing device; the inverting end of the first operational amplifier is connected to one end of the twelfth resistor and connected to the overcurrent threshold device through the tenth resistor; the output end of the first operational amplifier is connected to the other end of the twelfth resistor and connected to the cathode of the second diode through the third resistor; the anode of the second diode is connected to the anode of the third diode and the input end of the first inverter; the output end of the first inverter is connected to the B end of the first logic chip; and the cathode of the third diode is connected to the base of the first switch tube.

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