Protection circuit and electronic lock protection system

Abstract

The utility model discloses a protection circuit and an electronic lock protection system. The protection circuit comprises a first control unit, a second control unit, a trigger unit and a driving unit, the first control unit is used for generating control voltage based on the motor rotating speed characterization signal; the second control unit is connected with the first control unit, and the second control unit is used for generating a power-on or power-off control signal based on the control voltage; the control end of the trigger unit is connected with the second control unit to receive the control signal, the first end is connected with the power voltage, the second end is connected with the first output node, and the trigger unit is used for controlling connection and disconnection between the power voltage and the first output node based on the control signal; the driving unit is connected between the second output node and the reference voltage, and the driving unit is used for controlling connection and disconnection between the second output node and the reference voltage based on the driving signal. Dual protection of the electronic lock is achieved with low circuit cost, and the electronic lock is prevented from being opened by mistake in the working state of the centrifugal machine.

Description

Technical Field

[0001] This utility model belongs to the field of integrated circuit technology, specifically relating to a protection circuit and an electronic lock protection system. Background Technology

[0002] When a centrifuge is working, the motor runs at a very high speed, and the centrifuged object has a great deal of kinetic energy. If the centrifuge's electronic lock is accidentally opened while it is in operation (for example, if the centrifuge's electronic lock is affected by electromagnetic interference or the centrifuge software crashes), the centrifuged object may be thrown out and cause a strong impact on the surrounding area.

[0003] Therefore, in view of the above-mentioned technical problems, it is necessary to provide a protection circuit and an electronic lock protection system. Utility Model Content

[0004] The purpose of this invention is to provide a protection circuit and electronic lock protection system that can prevent the electronic lock of a centrifuge from being accidentally opened while the centrifuge is in operation.

[0005] To achieve the above objectives, the technical solution provided by a specific embodiment of this utility model is as follows:

[0006] A protection circuit includes: a first control unit, a second control unit, a triggering unit, and a driving unit;

[0007] The first control unit is used to generate a control voltage based on the motor speed characterization signal;

[0008] The second control unit is connected to the first control unit, and the second control unit is used to generate a control signal for powering on or off based on the control voltage;

[0009] The control terminal of the triggering unit is connected to the second control unit to receive the control signal. The first terminal is connected to the power supply voltage, and the second terminal is connected to the first output node. The triggering unit is used to control the on / off connection between the power supply voltage and the first output node based on the control signal.

[0010] The driving unit is connected between the second output node and the reference voltage, and the driving unit is used to control the on / off state between the second output node and the reference voltage based on the driving signal.

[0011] In one or more embodiments of this utility model, the first control unit includes a signal shaping unit and a waveform conversion unit; wherein, the first input terminal of the signal shaping unit receives a motor speed characterization signal, and the first output terminal is connected to the input terminal of the waveform conversion unit; the signal shaping unit is used to shape the motor speed characterization signal and generate a first output signal; the waveform conversion unit is used to perform frequency-to-voltage conversion on the first output signal to generate a voltage signal; the second input terminal of the signal shaping unit is connected to the output terminal of the waveform conversion unit; the signal shaping unit is used to invert the phase of the voltage signal and generate a control voltage through the second output terminal of the signal shaping unit.

[0012] In one or more embodiments of this utility model, the signal shaping unit includes a first Schmitt trigger and a second Schmitt trigger; the input terminal of the first Schmitt trigger receives a motor speed characterization signal, and the output terminal generates a first output signal, which is a square wave signal; the input terminal of the second Schmitt trigger receives a voltage signal, and the second Schmitt trigger is used to invert the phase of the voltage signal and generate a control voltage through the output terminal.

[0013] In one or more embodiments of this utility model, the waveform conversion unit includes a first capacitor, a second capacitor, a first diode, a second diode, a first resistor, and a second resistor; the first terminal of the first capacitor is connected to the first output terminal of the signal shaping unit and forms the input terminal of the waveform conversion unit, and the second terminal is connected to the cathode of the first diode and the anode of the second diode, and the anode of the first diode is connected to a reference voltage.

[0014] The cathode of the second diode is connected to the first end of the first resistor, the second end of the first resistor is connected to the first end of the second resistor and the first end of the second capacitor to form the output terminal of the waveform conversion unit, and the second end of the second resistor and the second end of the second capacitor are connected to the reference voltage.

[0015] In one or more embodiments of the present invention, the second control unit includes a first transistor, the control terminal of the first transistor is connected to the first control unit and receives a control voltage, the first terminal is connected to a reference voltage, and the second terminal is connected to the trigger unit and generates a control signal.

[0016] In one or more embodiments of this utility model, the triggering unit includes a relay, the relay includes a coil and contacts; a first end of the coil is connected to a power supply voltage, and a second end is connected to a second control unit to receive a control signal; a first end of the contacts is connected to a power supply voltage, and a second end is connected to the first output node.

[0017] In one or more embodiments of the present invention, the triggering unit further includes a third diode, the anode of which is connected to the second end of the coil and the second control unit, and the cathode is connected to the power supply voltage and the first end of the coil.

[0018] In one or more embodiments of the present invention, the driving unit includes a second transistor, the control terminal of the second transistor receives the driving signal, the first terminal is connected to a reference voltage, and the second terminal is connected to the second output node.

[0019] In one or more embodiments of the present invention, the driving unit further includes a filtering unit, the filtering unit including a third resistor and a fourth diode, the first end of the third resistor forming the input terminal of the driving unit to receive the driving signal, the second end being connected to the control terminal of the second transistor and the cathode of the fourth diode, and the anode of the fourth diode being connected to a reference voltage.

[0020] The technical solution provided by another specific embodiment of this utility model is as follows:

[0021] An electronic lock protection system includes: a protection circuit and an electronic lock, wherein the protection circuit is the protection circuit described in any embodiment, and the electronic lock includes an input positive terminal and an input negative terminal, the input positive terminal being connected to a first output node, and the input negative terminal being connected to a second output node.

[0022] In one or more embodiments of this utility model, the electronic lock protection system further includes a voltage regulator, wherein a first end of the voltage regulator is connected to the negative input terminal and a second end is connected to the positive input terminal.

[0023] Compared with the prior art, the protection circuit and electronic lock protection system of this utility model have low circuit cost. Based on the motor speed characterization signal, a control signal is generated to control the power-on or power-off of the electronic lock, which can realize dual protection for the centrifuge electronic lock and prevent the electronic lock from being opened accidentally while the centrifuge is working. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 This is a system block diagram of the protection circuit in this utility model;

[0026] Figure 2 This is a circuit diagram of the protection circuit in Embodiment 1 of this utility model;

[0027] Figures 3a-3e This is a waveform simulation diagram showing the change of voltage signal with the first output signal under five different conditions in Embodiment 1 of this utility model;

[0028] Figure 4 This is a circuit diagram of the electronic lock protection system in Embodiment 2 of this utility model;

[0029] Figure Labels

[0030] 10-First control unit; 11-Signal shaping unit; 12-Waveform conversion unit; 20-Second control unit; 30-Trigger unit; 40-Drive unit. Detailed Implementation

[0031] To enable those skilled in the art to better understand the technical solutions of this utility model, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, and not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort should fall within the protection scope of this utility model.

[0032] Unless otherwise expressly stated, throughout the specification and claims, the term "comprising" or its variations such as "including" or "comprises" shall be understood to include the stated elements or components without excluding other elements or other components.

[0033] The terms "coupled," "connected," or "linked" in this specification include both direct and indirect connections. An indirect connection is a connection made through an intermediate medium, such as an electrical conduction medium, which may have parasitic inductance or capacitance. Indirect connections may also include connections made through other active or passive devices to achieve the same or similar functional purpose, such as connections through switches, follower circuits, or other circuits or components. Furthermore, in this invention, terms such as "first" and "second" are primarily used to distinguish one technical feature from another, and do not necessarily require or imply any actual relationship, quantity, or order between these technical features.

[0034] In the detailed description of this specification, reference is made to the accompanying drawings, which form a part thereof, wherein like reference numerals always denote like parts, and wherein exemplary embodiments are shown by way of example that may be implemented. It should be understood that other embodiments may be utilized, and structural or logical changes may be made, without departing from the scope of this application. Therefore, the following detailed description should not be considered limiting.

[0035] The various operations in the specification may be described sequentially as multiple discrete actions or operations in a manner most conducive to understanding the claimed subject matter. However, the order of description should not be construed as implying that these operations must be sequentially related. Specifically, these operations may not be performed in the order presented. The described operations may be performed in a different order than in the described embodiments. Various additional operations may be performed in additional embodiments and / or the described operations may be omitted.

[0036] For the purposes of this application, the phrase "A and / or B" means (A), (B), or (A and B). For the purposes of this application, the phrase "A, B and / or C" means (A), (B), (C), (A and B), (A and C), (B and C), or (A, B and C).

[0037] Various components and devices may be referred to or shown in the singular (e.g., “MOS transistor”, “transistor”, “switch”, etc.) in this document, but only for the convenience of discussion, and any element referred to in the singular may include multiple such elements as taught herein.

[0038] The description uses the phrases "in this embodiment," "in other embodiments," or "in some embodiments," each of which may refer to one or more of the same or different embodiments. Furthermore, the terms "comprising," "including," "having," etc., used in relation to embodiments of this application are synonymous.

[0039] like Figure 1 As shown, a protection circuit of this utility model includes: a first control unit 10, a second control unit 20, a trigger unit 30, and a drive unit 40.

[0040] The first control unit 10 generates a control voltage V1 based on the motor speed characterization signal Speed. The second control unit 20 is connected to the first control unit 10 and generates a control signal S2 for powering on or off based on the control voltage V1. The control terminal of the trigger unit 30 is connected to the second control unit 20 to receive the control signal S2. The first terminal is connected to the power supply voltage VDD, and the second terminal is connected to the first output node P1. The trigger unit 30 controls the switching between the power supply voltage VDD and the first output node P1 based on the control signal S2. The drive unit 40 is connected between the second output node P2 and the reference voltage DGND and controls the switching between the second output node P2 and the reference voltage DGND based on the drive signal Control.

[0041] This utility model also discloses an electronic lock protection system, including the aforementioned protection circuit and an electronic lock. The electronic lock includes a positive input terminal and a negative input terminal. The positive input terminal is connected to a first output node P1, and the negative input terminal is connected to a second output node P2. This utility model achieves dual protection for the centrifuge electronic lock through a simple circuit design, preventing the electronic lock from being accidentally opened while the centrifuge is operating.

[0042] The present invention will be further described below with reference to specific embodiments.

[0043] Example 1:

[0044] like Figure 2 As shown, a protection circuit in this embodiment includes: a first control unit 10, a second control unit 20, a trigger unit 30, and a drive unit 40.

[0045] The first control unit 10 generates a control voltage V1 based on the motor speed characterization signal Speed. The second control unit 20 is connected to the first control unit 10 and generates a control signal S2 for powering on or off based on the control voltage V1. The control terminal of the trigger unit 30 is connected to the second control unit 20 to receive the control signal S2. The first terminal is connected to the power supply voltage, and the second terminal is connected to the first output node P1. The trigger unit 30 controls the connection and disconnection between the power supply voltage and the first output node P1 based on the control signal S2. The drive unit 40 is connected between the second output node P2 and the reference voltage DGND. The drive unit 40 controls the connection and disconnection between the second output node P2 and the reference voltage DGND based on the drive signal Control. For example, the reference voltage is ground potential DGND, and the power supply voltage is a 24V power supply.

[0046] The first control unit 10 includes a signal shaping unit 11 and a waveform conversion unit 12.

[0047] The first input terminal 1A of the signal shaping unit 11 receives the motor speed characterization signal Speed, and the first output terminal 1Y is connected to the input terminal of the waveform conversion unit 12. The signal shaping unit 11 is used to shape the motor speed characterization signal Speed ​​and generate the first output signal S1. The waveform conversion unit 12 is used to perform frequency-voltage conversion on the first output signal S1 to generate the voltage signal Speed_1.

[0048] The second input terminal 2A of the signal shaping unit 11 is connected to the output terminal of the waveform conversion unit 12. The signal shaping unit 11 is used to invert the phase of the voltage signal Speed_1 and generate the control voltage V1 through the second output terminal 2Y of the signal shaping unit 11.

[0049] For example, the signal shaping unit 11 is a dual-channel Schmitt trigger inverter, that is, the signal shaping unit 11 includes a first Schmitt trigger and a second Schmitt trigger. The input terminal of the first Schmitt trigger forms the first input terminal 1A of the signal shaping unit 11 and receives the motor speed characterization signal Speed, and the output terminal forms the first output terminal 1Y of the signal shaping unit 11 and generates a first output signal S1.

[0050] It should be noted that the motor speed characterization signal Speed ​​in this embodiment is a square wave signal. Based on the input characteristics of the first Schmitt trigger, the slowly changing or noisy motor speed characterization signal Speed ​​can be shaped to output a clean square wave signal, that is, the first output signal S1 is a square wave signal. Furthermore, the signal shaping unit 11 is connected between the 3.3V power supply and the reference voltage DGND. The signal shaping unit 11 also includes a third capacitor C3, which is connected between the 3.3V power supply and the reference voltage DGND.

[0051] like Figure 2 As shown, in this embodiment, the waveform conversion unit 12 includes a first capacitor C1, a second capacitor C2, a first diode D1, a second diode D2, a first resistor R1, and a second resistor R2.

[0052] The first terminal of the first capacitor C1 is connected to the first output terminal 1Y of the signal shaping unit 11 and forms the input terminal of the waveform conversion unit 12. The second terminal is connected to the cathode of the first diode D1 and the anode of the second diode D2. The anode of the first diode D1 is connected to the reference voltage DGND. The cathode of the second diode D2 is connected to the first terminal of the first resistor R1. The second terminal of the first resistor R1 is connected to the first terminal of the second resistor R2 and the first terminal of the second capacitor C2 and forms the output terminal of the waveform conversion unit 12. The second terminal of the second resistor R2 and the second terminal of the second capacitor C2 are connected to the reference voltage DGND.

[0053] The input of the second Schmitt trigger receives the voltage signal Speed_1. The second Schmitt trigger is used to invert the phase of the voltage signal Speed_1 and generate a control voltage V1 at the output.

[0054] It is understandable that when the motor rotates, the voltage value of the voltage signal Speed_1 is always greater than the reference voltage DGND (refer to...). Figure 2 As shown, in this embodiment, the reference voltage DGND is the ground potential. After phase inversion, the control voltage V1 obtained is a low-level signal. When the motor speed is 0 or the motor speed is very low, the frequency of the motor speed characterization signal Speed ​​is low, and the waveform of the motor speed characterization signal Speed ​​is a constant high-level signal or a constant low-level signal. That is, at this time, the first output signal S1 is a constant high-level signal or a constant low-level signal.

[0055] When the first output signal S1 is a constant high-level signal, after the first capacitor C1, the first resistor R1 and the second resistor R2 finish charging the second capacitor C2, the second resistor R2 will gradually discharge until the voltage at the second terminal of the second capacitor C2 is zero, that is, the voltage signal Speed_1 is a low-level signal, and the control voltage V1 generated by the second Schmitt trigger is a high-level signal.

[0056] When the first output signal S1 is a constant low-level signal, the second resistor R2 will gradually discharge until the voltage at the second terminal of the second capacitor C2 is zero, that is, the voltage signal Speed_1 is a low-level signal, and the control voltage V1 generated by the second Schmitt trigger is a high-level signal.

[0057] like Figures 3a-3e As shown, the waveform of the voltage signal Speed_1 follows the frequency change of the first output signal S1. The higher the frequency of the first output signal S1, the closer the waveform of the voltage signal Speed_1 is to a smooth straight line. That is, the waveform conversion unit 12 performs frequency-voltage conversion on the first output signal S1 to generate a voltage signal Speed_1 that is related to the frequency of the first output signal S1.

[0058] Specifically, when the motor speed is 6000 rpm, the frequency of the first output signal S1 is 100 Hz, and the waveform of the voltage signal Speed_1 is as follows: Figure 3a As shown; when the motor speed is 800 rpm, the frequency of the first output signal S1 is 10 Hz, and the waveform of the voltage signal Speed_1 is as follows. Figure 3b As shown; when the motor speed is 60 rpm, the frequency of the first output signal S1 is 1 Hz, and the waveform of the voltage signal Speed_1 is as follows. Figure 3cAs shown. When the motor speed is 0, the motor speed characterization signal Speed ​​is a constant high-level signal or a constant low-level signal. Therefore, the first output signal S1 is a constant high-level signal (see Figure 1). Figure 3d (as shown) or a constant low-level signal (see) Figure 3e As shown in the figure, at this time the voltage signal Speed_1 is a low level signal.

[0059] like Figure 2 As shown, the second control unit 20 includes a first transistor Q1. The control terminal of the first transistor Q1 is connected to the first control unit 10 and receives a control voltage V1. Its first terminal is connected to a reference voltage DGND, and its second terminal is connected to a trigger unit 30 and generates a control signal S2. Exemplarily, the first transistor Q1 is an NPN bipolar junction transistor, with its first terminal being the emitter, its second terminal being the collector, and its control terminal being the base.

[0060] like Figure 2 As shown, the trigger unit 30 includes a relay and a third diode D3. The relay includes a coil 31 and a contact 32.

[0061] The first end of coil 31 is connected to the power supply voltage, and the second end is connected to the second control unit 20 to receive the control signal S2. The first end of contact 32 is connected to the power supply voltage, and the second end is connected to the first output node P1. The anode of the third diode D3 is connected to the second end of coil 31 and the second control unit 20, and the cathode is connected to the power supply voltage and the first end of coil 31. The third diode D3 is used to implement voltage regulation protection.

[0062] When the control voltage V1 is low, the first transistor Q1 controls itself to turn off, the control signal S2 (i.e. the voltage at the second end of coil 31) is pulled up to a high level by the power supply voltage, there is no voltage difference across coil 31, the contact 32 is released, and the first output node P1 is powered down.

[0063] When the control voltage V1 is high, the first transistor Q1 controls itself to turn on, the second terminal of the first transistor Q1 is pulled down to low level, the control signal S2 (i.e. the voltage at the second terminal of coil 31) is low level, a voltage difference appears across the two ends of coil 31 to attract the contact 32, and the first output node P1 is powered on.

[0064] The driving unit 40 includes a second transistor Q2 and a filtering unit 41. The control terminal of the second transistor Q2 receives the driving signal Control, its first terminal is connected to the reference voltage DGND, and its second terminal is connected to the second output node P2. The filtering unit 41 includes a third resistor R3 and a fourth diode D4. The first terminal of the third resistor R3 forms the input terminal of the driving unit 40 to receive the driving signal Control, and its second terminal is connected to the control terminal of the second transistor Q2 and the cathode of the fourth diode D4. The anode of the fourth diode D4 is connected to the reference voltage DGND. It can be understood that the driving unit 40 is used to control whether the second output node P2 is grounded based on the driving signal Control.

[0065] For example, the second transistor Q2 is an N-channel MOS transistor, with the first terminal of the second transistor Q2 being the source, the second terminal being the drain, and the control terminal being the gate.

[0066] Example 2:

[0067] like Figure 4 As shown, an electronic lock 50 protection system according to this embodiment includes a protection circuit and an electronic lock 50. The protection circuit includes a first control unit 10, a second control unit 20, a trigger unit 30, and a drive unit 40. The circuit structure and working principle of the protection circuit in this embodiment are the same as those described in Embodiment 1, and will not be repeated here. The electronic lock 50 includes a positive input terminal J5 and a negative input terminal J4. The positive input terminal J5 is connected to the first output node P1, and the negative input terminal J4 is connected to the second output node P2.

[0068] The electronic lock 50 protection system in this embodiment also includes a voltage regulator 51. The first terminal of the voltage regulator 51 is connected to the negative input J4, and the second terminal is connected to the positive input J5. Preferably, the voltage regulator 51 includes a Zener diode D5.

[0069] The electronic lock 50 protection system in this embodiment also includes a motor Hall sensor. The motor Hall sensor is used to obtain the motor speed characterization signal Speed ​​based on the rotation of the motor. For each rotation of the motor, it will send a one-cycle square wave signal (i.e., the motor speed characterization signal Speed). The frequency f of the square wave signal (i.e., the motor speed characterization signal Speed) is proportional to the speed n (rpm) of the motor, f = n / 60.

[0070] In this embodiment, the negative input J4 of the electronic lock 50 is controlled by the drive unit 40, and the positive input J5 of the electronic lock 50 is controlled by the first control unit 10, the second control unit 20, and the trigger unit 30. It is understood that the electronic lock 50 can only operate normally when the negative input J4 is connected to the reference voltage DGND and the positive input J5 is connected to the power supply voltage, thus providing dual protection for the electronic lock 50 and preventing it from being accidentally opened while the motor is rotating.

[0071] Specifically, when the motor rotates, the control voltage V1 is at a low level, and the first transistor Q1 is turned off to disconnect the control power supply voltage of the trigger unit 30 from the first output node P1, thus cutting off the power supply to the positive input of the electronic lock 50. At this time, even if the drive signal Control is at a high level and the drive unit 40 controls the second output node P2 (the negative input of the electronic lock 50) to conduct with the reference voltage DGND, the electronic lock 50 will not work normally, preventing the electronic lock 50 from being accidentally opened due to electromagnetic interference or software crashes while the motor is running.

[0072] When the motor stops rotating or the motor speed is very low, the control voltage V1 is at a high level, the first transistor Q1 is turned on so that the control power supply voltage of the trigger unit 30 is connected to the first output node P1, and the positive input of the electronic lock 50 is connected to the power supply. At this time, based on the control of the drive signal Control, the drive unit 40 can control the second output node P2 (the negative input of the electronic lock 50) to open or close the connection with the reference voltage DGND, thereby controlling whether the electronic lock 50 is working properly.

[0073] As can be seen from the above technical solutions, this utility model has the following beneficial effects:

[0074] This invention achieves dual protection for the centrifuge electronic lock with low circuit cost. Based on the motor speed characterization signal Speed, a control signal S2 is generated to control the power-on or power-off of the electronic lock, thus preventing the electronic lock from being accidentally opened while the centrifuge is in operation.

[0075] It will be apparent to those skilled in the art that this invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of this invention. Therefore, the embodiments should be considered illustrative and non-limiting in all respects, and the scope of this invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within this invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0076] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A protection circuit, characterized by, The application relates to a motor control circuit. The motor control circuit comprises a first control unit, a second control unit, a trigger unit and a driving unit. The first control unit is used for generating a control voltage based on a motor speed representation signal. The second control unit is connected with the first control unit, and the second control unit is used for generating a control signal for power-on or power-off based on the control voltage. The control end of the trigger unit is connected with the second control unit to receive the control signal, the first end is connected with a power supply voltage, and the second end is connected with a first output node, and the trigger unit is used for controlling the on-off between the power supply voltage and the first output node based on the control signal. The driving unit is connected between a second output node and a reference voltage, and the driving unit is used for controlling the on-off between the second output node and the reference voltage based on a driving signal.

2. The protection circuit of claim 1, wherein, The first control unit comprises a signal shaping unit and a waveform conversion unit. The first input end of the signal shaping unit receives the motor speed representation signal, the first output end is connected with the input end of the waveform conversion unit, the signal shaping unit is used for signal shaping of the motor speed representation signal and generates a first output signal, and the waveform conversion unit is used for frequency-voltage conversion of the first output signal to generate a voltage signal. The second input end of the signal shaping unit is connected with the output end of the waveform conversion unit, and the signal shaping unit is used for phase inversion of the voltage signal and generates the control voltage through the second output end of the signal shaping unit.

3. The protection circuit of claim 2, wherein, The signal shaping unit comprises a first Schmitt trigger and a second Schmitt trigger. The input end of the first Schmitt trigger receives the motor speed representation signal, and the output end generates the first output signal which is a square wave signal. The input end of the second Schmitt trigger receives the voltage signal, and the second Schmitt trigger is used for phase inversion of the voltage signal and generates the control voltage through the output end.

4. The protection circuit of claim 2, wherein, The waveform conversion unit comprises a first capacitor, a second capacitor, a first diode, a second diode, a first resistor and a second resistor. The first end of the first capacitor is connected with the first output end of the signal shaping unit and forms the input end of the waveform conversion unit, the second end is connected with the cathode of the first diode and the anode of the second diode, and the anode of the first diode is connected with a reference voltage. The cathode of the second diode is connected with the first end of the first resistor, the second end of the first resistor is connected with the first end of the second resistor and the first end of the second capacitor and forms the output end of the waveform conversion unit, and the second end of the second resistor and the second end of the second capacitor are connected with the reference voltage.

5. The protection circuit of claim 1, wherein, The second control unit comprises a first transistor, the control end of the first transistor is connected with the first control unit and receives the control voltage, the first end is connected with a reference voltage, and the second end is connected with the trigger unit and generates the control signal.

6. The protection circuit of claim 1, wherein, The trigger unit comprises a relay, and the relay comprises a coil and a contact. The first end of the coil is connected with a power voltage, and the second end is connected with the second control unit to receive the control signal. The first end of the contact is connected with the power voltage, and the second end is connected with the first output node.

7. The protection circuit of claim 6, wherein, The trigger unit further comprises a third diode, the anode of the third diode is connected with the second end of the coil and the second control unit, and the cathode is connected with the power voltage and the first end of the coil.

8. The protection circuit of claim 1, wherein, The drive unit comprises a second transistor, the control end of the second transistor receives the drive signal, the first end is connected with a reference voltage, and the second end is connected with the second output node.

9. The protection circuit of claim 8, wherein, The drive unit further comprises a filter unit, the filter unit comprises a third resistor and a fourth diode, the first end of the third resistor forms an input end of the drive unit to receive the drive signal, the second end is connected with the control end of the second transistor and the cathode of the fourth diode, and the anode of the fourth diode is connected with a reference voltage.

10. An electronic lock protection system, characterized by Comprise: A protection circuit and an electronic lock; The protection circuit is the protection circuit in any one of claims 1-9; The electronic lock comprises an input positive electrode and an input negative electrode, the input positive electrode is connected with the first output node, and the input negative electrode is connected with the second output node.

11. The electronic lock protection system of claim 10, wherein, The electronic lock protection system further comprises a voltage stabilizing device, the first end of the voltage stabilizing device is connected with the input negative electrode, and the second end is connected with the input positive electrode.

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