Soft start circuit of vacuum sealer

Abstract

The utility model discloses a soft start circuit of a vacuum sealer, which relates to the technical field of soft start, and comprises a power supply module used for power supply processing and power supply; the timing control module is used for controlling the soft start duration of the soft start control module; the soft start control module is used for carrying out current limiting processing and supplying power to the vacuum sealer module; the voltage sampling module is used for performing voltage sampling on the electric energy output by the power supply module and the soft start control module; the difference value detection module is used for carrying out subtraction processing on the sampling signals; and the difference comparison module is used for setting a comparison threshold value, judging the current limiting degree and carrying out power-off protection when the soft start control module exceeds the current limiting degree. The soft start circuit of the vacuum sealer reduces the influence of a surge power supply when the vacuum sealer module is started, prevents the power loss of the circuit from being increased due to the damage of the soft start control module, and improves the stability and safety of the power supply circuit.

Description

Technical Field

[0001] The utility model relates to the technical field of soft starting, in particular to a soft starting circuit of a vacuum sealing machine. Background Art

[0002] Most of the power supplies for vacuum air sealing machines use switching power supplies, and there are capacitors, rectifiers and other components at their input ends. At the moment of power-on, they are easily affected by surge currents. Soft starting can reduce the impact of surge currents on vacuum sealing machines at the moment of starting, and improve circuit reliability. However, during the soft starting process, if the current limiting resistor is damaged, it is easy to increase circuit power loss and reduce the power supply efficiency of the vacuum sealing machine. At the same time, it is easy to reduce the stability of the power supply circuit. The circuit safety of the vacuum sealing machine during soft starting is low, so it needs to be improved. Utility Model Content

[0003] The embodiment of the utility model provides a soft start circuit of a vacuum sealer to solve the problems raised in the above background technology.

[0004] In order to achieve the above purpose, the utility model provides the following technical solutions:

[0005] The soft start circuit of the vacuum sealer includes: a power supply module, a timing control module, a soft start control module, a voltage sampling module, a difference detection module, a difference comparison module and a vacuum sealer module;

[0006] A power module is used to receive AC power and transform, rectify and stabilize the AC power;

[0007] A timing control module, connected to the power module and the difference comparison module, for receiving the electric energy after voltage stabilization by the power module and starting the timing operation, for outputting a first control signal after the timing ends, for receiving a protection signal output by the difference comparison module and stopping the timing operation;

[0008] A soft start control module, connected to the power module, the timing control module, the vacuum sealer module and the difference comparison module, for performing current limiting processing on the electric energy after rectification processing by the power module, for receiving a first control signal and directly transmitting the electric energy after rectification processing by the power module to the vacuum sealer module and stopping the current limiting operation, and for receiving a protection signal output by the difference comparison module and stopping the current limiting operation;

[0009] A voltage sampling module, connected to the power module and the soft start control module, for performing voltage sampling on the electric energy after rectification by the power module and outputting a first sampling signal, and for performing voltage sampling on the electric energy after current limiting and outputting a second sampling signal;

[0010] A difference detection module, connected to the voltage sampling module, the timing control module and the difference comparison module, for performing subtraction processing on the first sampling signal and the second sampling signal and outputting a first difference signal, for receiving the first control signal and the protection signal output by the difference comparison module and stopping the subtraction operation;

[0011] A difference comparison module, used to set a comparison threshold and output a protection signal when the first difference signal is greater than the comparison threshold;

[0012] The vacuum sealer module is used to receive the electric energy output by the soft start control module.

[0013] As a further solution of the utility model: the power supply module includes a power supply interface, a first transformer, a first rectifier, a voltage stabilizer and a second capacitor; the soft start control module includes a first current limiting resistor, a first relay switch and a second relay switch; the vacuum sealer module includes a first capacitor and a vacuum sealer;

[0014] Preferably, the first end and the second end of the power interface are respectively connected to 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 respectively connected to the first input end and the second input end of the first rectifier, the first output end of the first rectifier is connected to the input end of the voltage regulator, one end of the first current limiting resistor and the moving end of the first relay switch, the other end of the first current limiting resistor is connected to the moving end of the second relay switch, the fixed end of the first relay switch is connected to the fixed end of the second relay switch, one end of the first capacitor and the power supply end of the vacuum sealer, the second output end of the first rectifier, the other end of the first capacitor, the ground end of the vacuum sealer, the ground end of the voltage regulator and one end of the second capacitor are all grounded, and the other end of the second capacitor is connected to the output end of the voltage regulator and the timing control module.

[0015] As a further solution of the utility model: the timing control module includes a ninth resistor, a first power tube, a first switch tube and a timing control device;

[0016] Preferably, the drain of the first power tube is connected to the output end of the voltage regulator and is connected to the collector of the first switching tube and the gate of the first power tube through a ninth resistor, the source of the first power tube is connected to the power supply end of the timing control device, the output end of the timing control device is connected to the soft start control module, the emitter of the first switching tube and the ground end of the timing control device are grounded, and the base of the first switching tube is connected to the difference comparison module.

[0017] As a further solution of the utility model: the soft start control module also includes a tenth resistor, a first relay, a second switch tube, a first diode, a third switch tube and a second relay;

[0018] Preferably, the base of the second switch tube is connected to the anode of the first diode and is connected to the output end of the timing control device through a tenth resistor, the cathode of the first diode is connected to the difference comparison module and the base of the third switch tube, the emitter of the third switch tube and the emitter of the second switch tube are both grounded, the collector of the second switch tube and the collector of the third switch tube are respectively connected to one end of the first relay and one end of the second relay, and the other end of the first relay and the other end of the second relay are both connected to the output end of the regulator.

[0019] As a further solution of the utility model: the voltage sampling module includes a first resistor, a second resistor, a third resistor and a fourth resistor;

[0020] Preferably, the first end of the first resistor and the first end of the third resistor are respectively connected to the first output end of the first rectifier and the fixed end of the second relay switch, the second end of the first resistor is grounded through the second resistor, and the second end of the third resistor is grounded through the fourth resistor.

[0021] As a further solution of the utility model: the difference detection module includes a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a first operational amplifier and a fourth switch tube;

[0022] Preferably, the in-phase terminal of the first operational amplifier is connected to one end of the sixth resistor and is connected to the second end of the first resistor through the fifth resistor, the other end of the sixth resistor is grounded, the inverting terminal of the first operational amplifier is connected to one end of the eighth resistor and is connected to the second end of the third resistor through the seventh resistor, the output terminal of the first operational amplifier is connected to the difference comparison module and the other end of the eighth resistor, the base of the fourth switching tube is connected to the difference comparison module, the collector of the fourth switching tube is connected to the power supply terminal of the first operational amplifier, and the emitter of the fourth switching tube is connected to the first end of the third resistor.

[0023] As a further solution of the utility model: the difference comparison module includes a first comparator, a first threshold device, a second diode, a third diode and an eleventh resistor;

[0024] Preferably, the in-phase end of the first comparator is connected to the cathode of the second diode and the output end of the first operational amplifier, the inverting end of the first comparator is connected to the first threshold device, the output end of the first comparator is connected to the anode of the second diode and connected to the base of the first switching tube and the anode of the third diode through the eleventh resistor, and the cathode of the third diode is connected to the base of the fourth switching tube and the base of the third switching tube.

[0025] Compared with the prior art, the beneficial effects of the utility model are as follows: the soft start circuit of the vacuum sealer of the utility model controls the soft start control module to perform soft start work by the timing control module, thereby reducing the influence of surge power supply when the vacuum sealer module is started, and at the same time, the difference detection module cooperates with the voltage sampling module to obtain the difference between the electric energy input to the soft start control module and the electric energy output by the soft start control module, and judges the current limiting degree of the soft start control module. When the current limiting degree exceeds the set comparison threshold, the difference comparison module disconnects the work of the soft start control module, stops the work of the timing control module and the difference detection module, performs power-off protection, avoids increasing the power loss of the circuit due to damage to the soft start control module, and improves the stability and safety of the power supply circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the utility model, the drawings required for use in the description of the embodiments of the utility model will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0027] Figure 1 The present invention is a block diagram of the principle of a soft start circuit for a vacuum sealer provided in an example of the present invention.

[0028] Figure 2 A circuit diagram of a soft start circuit for a vacuum sealer provided in an example of the utility model.

[0029] Figure 3 This is a connection circuit diagram of a difference comparison module provided in an example of the utility model. DETAILED DESCRIPTION

[0030] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0031] In one embodiment, see Figure 1 , a soft start circuit of a vacuum sealer, comprising: a power supply module 1, a timing control module 2, a soft start control module 3, a voltage sampling module 4, a difference detection module 5, a difference comparison module 6 and a vacuum sealer module 7;

[0032] Specifically, the power module 1 is used to receive AC power and transform, rectify and stabilize the AC power;

[0033] The timing control module 2 is connected to the power module 1 and the difference comparison module 6, and is used to receive the electric energy after the voltage stabilization process of the power module 1 and start the timing work, and is used to output the first control signal after the timing ends, and is used to receive the protection signal output by the difference comparison module 6 and stop the timing work;

[0034] The soft start control module 3 is connected to the power module 1, the timing control module 2, the vacuum sealer module 7 and the difference comparison module 6, and is used for current limiting the electric energy after rectification by the power module 1, for receiving the first control signal and directly transmitting the electric energy after rectification by the power module 1 to the vacuum sealer module 7 and stopping the current limiting operation, and for receiving the protection signal output by the difference comparison module 6 and stopping the current limiting operation;

[0035] A voltage sampling module 4 is connected to the power module 1 and the soft start control module 3, and is used to perform voltage sampling on the electric energy after rectification by the power module 1 and output a first sampling signal, and is used to perform voltage sampling on the electric energy after current limiting and output a second sampling signal;

[0036] The difference detection module 5 is connected to the voltage sampling module 4, the timing control module 2 and the difference comparison module 6, and is used to perform subtraction processing on the first sampling signal and the second sampling signal and output a first difference signal, and is used to receive the first control signal and the protection signal output by the difference comparison module 6 and stop the subtraction work;

[0037] The difference comparison module 6 is used to set a comparison threshold and output a protection signal when the first difference signal is greater than the comparison threshold;

[0038] The vacuum sealer module 7 is used to receive the electric energy output by the soft start control module 3 .

[0039] In a specific embodiment, the power supply module 1 can adopt a power supply circuit composed of a power supply interface, a transformer, a rectifier, a voltage stabilizer, etc. to access AC power and perform voltage transformation, rectification and voltage stabilization on the AC power; the timing control module 2 can adopt a timing control circuit composed of a power tube, a timing control device, etc., which starts timing work after power is supplied, and continuously outputs a first control signal in a high-level state after the timing ends; the soft-start control module 3 can adopt a soft-start control circuit composed of a relay, a current-limiting resistor, a triode, etc., which can control the current limiting work and the power transmission work; the voltage sampling module 4 can adopt a voltage sampling circuit composed of a resistor, respectively The electric energy output by the power supply module 1 and the electric energy output by the soft start control module 3 are subjected to voltage sampling; the above-mentioned difference detection module 5 can adopt a difference detection circuit composed of an operational amplifier, a resistor, etc., and can detect the current limiting degree of the soft start control module 3; the above-mentioned difference comparison module 6 can adopt a difference comparison circuit composed of a comparator, a diode, etc., and can set a comparison threshold. When comparing the signal output by the difference detection module 5 with the comparison threshold, the comparison threshold is used to judge the current limiting degree of the soft start control module 3; the above-mentioned vacuum sealer module 7 can adopt a vacuum sealer circuit composed of a capacitor and a vacuum sealer, and the vacuum sealer receives the electric energy output by the soft start control module 3.

[0040] In another embodiment, see Figure 1 , Figure 2 and Figure 3 The power supply module 1 includes a power supply interface, a first transformer B1, a first rectifier T1, a voltage stabilizer and a second capacitor C2; the soft start control module 3 includes a first current limiting resistor RC1, a first relay switch K1-1 and a second relay switch K2-1; the vacuum sealer module 7 includes a first capacitor C1 and a vacuum sealer;

[0041] Specifically, the first end and the second end of the power interface are respectively connected to the first end and the second end of the primary side of the first transformer B1, the first end and the second end of the secondary side of the first transformer B1 are respectively connected to the first input end and the second input end of the first rectifier T1, the first output end of the first rectifier T1 is connected to the input end of the voltage regulator, one end of the first current limiting resistor RC1 and the moving end of the first relay switch K1-1, the other end of the first current limiting resistor RC1 is connected to the moving end of the second relay switch K2-1, the fixed end of the first relay switch K1-1 is connected to the fixed end of the second relay switch K2-1, one end of the first capacitor C1 and the power supply end of the vacuum sealer, the second output end of the first rectifier T1, the other end of the first capacitor C1, the ground end of the vacuum sealer, the ground end of the voltage regulator and one end of the second capacitor C2 are all grounded, and the other end of the second capacitor C2 is connected to the output end of the voltage regulator and the timing control module 2.

[0042] In a specific embodiment, the above-mentioned voltage stabilizer can be a 7812 three-terminal integrated voltage stabilizer; the above-mentioned first relay switch K1-1 can be a normally open switch, and the second relay switch K2-1 can be a normally closed switch.

[0043] Furthermore, the timing control module 2 includes a ninth resistor R9, a first power tube Q1, a first switch tube VT1 and a timing control device;

[0044] Specifically, the drain of the first power tube Q1 is connected to the output end of the voltage regulator and is connected to the collector of the first switch tube VT1 and the gate of the first power tube Q1 through the ninth resistor R9, the source of the first power tube Q1 is connected to the power supply end of the timing control device, the output end of the timing control device is connected to the soft start control module 3, the emitter of the first switch tube VT1 and the ground end of the timing control device are grounded, and the base of the first switch tube VT1 is connected to the difference comparison module 6.

[0045] In a specific embodiment, the first power tube Q1 can be an N-channel field effect tube; the first switch tube VT1 can be an NPN transistor; the timing control device can be composed of a NE555 chip, a diode, a resistor and a capacitor to achieve continuous output of a high-level first control signal after a period of startup, which will not be described in detail.

[0046] Furthermore, the soft start control module 3 further includes a tenth resistor R10, a first relay K1, a second switch tube VT2, a first diode D1, a third switch tube VT3 and a second relay K2;

[0047] Specifically, the base of the second switch tube VT2 is connected to the anode of the first diode D1 and is connected to the output end of the timing control device through the tenth resistor R10, the cathode of the first diode D1 is connected to the difference comparison module 6 and the base of the third switch tube VT3, the emitter of the third switch tube VT3 and the emitter of the second switch tube VT2 are both grounded, the collector of the second switch tube VT2 and the collector of the third switch tube VT3 are respectively connected to one end of the first relay K1 and one end of the second relay K2, and the other end of the first relay K1 and the other end of the second relay K2 are both connected to the output end of the regulator.

[0048] In a specific embodiment, the first relay K1 controls the closing and opening of the first relay switch K1-1 by magnetic attraction, and the second relay K2 controls the closing and opening of the second relay switch K2-1 by magnetic attraction; the second switch tube VT2 and the third switch tube VT3 can both be NPN transistors.

[0049] Further, the voltage sampling module 4 includes a first resistor R1, a second resistor R2, a third resistor R3 and a fourth resistor R4;

[0050] Specifically, the first end of the first resistor R1 and the first end of the third resistor R3 are respectively connected to the first output end of the first rectifier T1 and the fixed end of the second relay switch K2-1, the second end of the first resistor R1 is grounded through the second resistor R2, and the second end of the third resistor R3 is grounded through the fourth resistor R4.

[0051] In a specific embodiment, the first resistor R1 and the second resistor R2 perform voltage sampling on the electric energy output by the first rectifier T1; the third resistor R3 and the fourth resistor R4 perform voltage sampling on the electric energy transmitted by the second relay switch K2-1.

[0052] Further, the difference detection module 5 includes a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a first operational amplifier OP1 and a fourth switch tube VT4;

[0053] Specifically, the in-phase end of the first operational amplifier OP1 is connected to one end of the sixth resistor R6 and is connected to the second end of the first resistor R1 through the fifth resistor R5, the other end of the sixth resistor R6 is grounded, the inverting end of the first operational amplifier OP1 is connected to one end of the eighth resistor R8 and is connected to the second end of the third resistor R3 through the seventh resistor R7, the output end of the first operational amplifier OP1 is connected to the difference comparison module 6 and the other end of the eighth resistor R8, the base of the fourth switch tube VT4 is connected to the difference comparison module 6, the collector of the fourth switch tube VT4 is connected to the power supply end of the first operational amplifier OP1, and the emitter of the fourth switch tube VT4 is connected to the first end of the third resistor R3.

[0054] In a specific embodiment, the first operational amplifier OP1 may be an LM158 operational amplifier, which cooperates with the fifth resistor R5, the sixth resistor R6, the seventh resistor R7 and the eighth resistor R8 to perform subtraction processing on the electric energy input to the fifth resistor R5 and the electric energy input to the seventh resistor R7; the fourth switch tube VT4 may be a PNP transistor.

[0055] Further, the difference comparison module 6 includes a first comparator A1, a first threshold device, a second diode D2, a third diode D3 and an eleventh resistor R11;

[0056] Specifically, the in-phase end of the first comparator A1 is connected to the cathode of the second diode D2 and the output end of the first operational amplifier OP1, the inverting end of the first comparator A1 is connected to the first threshold device, the output end of the first comparator A1 is connected to the anode of the second diode D2 and connected to the base of the first switching tube VT1 and the anode of the third diode D3 through the eleventh resistor R11, and the cathode of the third diode D3 is connected to the base of the fourth switching tube VT4 and the base of the third switching tube VT3.

[0057] In a specific embodiment, the first comparator A1 can be an LM358 comparator, which cooperates with the second diode D2 to perform self-locking control; the first threshold device can be composed of a reference power supply and a resistor to provide a comparison threshold, which is used to determine the current limiting degree of the soft start control module 3.

[0058] In the soft start circuit of the vacuum sealer of this embodiment, AC power is connected to the power interface, isolated and transformed by the first transformer B1, rectified by the first rectifier T1, and stabilized by the voltage stabilizer. At this time, the power is transmitted to the vacuum sealer through the first current resistor and the second relay switch K2-1, and the input power is current limited. At the same time, the power output by the voltage stabilizer triggers the first power tube Q1 to turn on, the timing control device is powered on and starts timing, the first resistor R1 and the second resistor R2 sample the voltage input to the first current limiting resistor RC1, the third resistor R3 and the fourth resistor R4 sample the voltage transmitted by the second relay switch K2-1, and the first operational amplifier OP1 cooperates with the fifth resistor R5, the sixth resistor R6, the seventh resistor R7 and the eighth resistor R8 to perform subtraction processing on the sampled signal. When the difference between the voltage input to the first current limiting resistor RC1 and the voltage output by the first current limiting resistor RC1 is large and greater than the first threshold value set by the device, the voltage is reduced to zero. When the comparison threshold is reached, that is, the resistance of the first current limiting resistor RC1 increases due to a fault, the first comparator A1 will output a high level signal and control the third switch tube VT3 and the first switch tube VT1 to be turned on, the fourth switch tube VT4 to be turned off, the second relay K2 controls the second relay switch K2-1 to be turned off, the first power tube Q1 to be turned off, and the first operational amplifier OP1 to stop working. At this time, no power is input to the vacuum sealing machine, and the circuit stops working. If the first current limiting resistor RC1 does not increase, the first comparator A1 will output a low level. At this time, after the timing control device ends, the output end of the timing control device outputs a high level and controls the second switch tube VT2 and the third switch tube VT3 to be turned on, controls the fourth switch tube VT4 to be turned off, the first relay switch K1-1 to be closed, the second relay switch K2-1 to be turned off, and the soft start is stopped. The electric energy output by the power supply module 1 is directly transmitted to the vacuum sealing machine through the first relay switch K1-1.

[0059] It is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be regarded as exemplary and non-restrictive from any point of view, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention. Any reference numeral in a claim should not be regarded as limiting the claim to which it relates.

[0060] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. The soft start circuit of the vacuum sealer is characterized by: The soft start circuit of the vacuum sealer includes: a power supply module, a timing control module, a soft start control module, a voltage sampling module, a difference detection module, a difference comparison module and a vacuum sealer module; The power module is used to receive AC power and perform voltage transformation, rectification and voltage stabilization on the AC power; The timing control module is connected to the power module and the difference comparison module, and is used to receive the electric energy after voltage stabilization by the power module and start the timing operation, to output the first control signal after the timing ends, and to receive the protection signal output by the difference comparison module and stop the timing operation; The soft start control module is connected to the power module, the timing control module, the vacuum sealer module and the difference comparison module, and is used to perform current limiting processing on the electric energy after rectification processing by the power module, to receive the first control signal and directly transmit the electric energy after rectification processing by the power module to the vacuum sealer module and stop the current limiting operation, and to receive the protection signal output by the difference comparison module and stop the current limiting operation; The voltage sampling module is connected to the power module and the soft start control module, and is used to perform voltage sampling on the electric energy after rectification by the power module and output a first sampling signal, and is used to perform voltage sampling on the electric energy after current limiting and output a second sampling signal; The difference detection module is connected to the voltage sampling module, the timing control module and the difference comparison module, and is used to perform subtraction processing on the first sampling signal and the second sampling signal and output a first difference signal, and is used to receive the first control signal and the protection signal output by the difference comparison module and stop the subtraction work; The difference comparison module is used to set a comparison threshold and output a protection signal when the first difference signal is greater than the comparison threshold; The vacuum sealer module is used to receive the electric energy output by the soft start control module.

2. The soft start circuit of the vacuum sealer according to claim 1, characterized in that: The power supply module includes a power supply interface, a first transformer, a first rectifier, a voltage stabilizer and a second capacitor; the soft start control module includes a first current limiting resistor, a first relay switch and a second relay switch; the vacuum sealer module includes a first capacitor and a vacuum sealer; The first end and the second end of the power interface are respectively connected to 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 respectively connected to the first input end and the second input end of the first rectifier, the first output end of the first rectifier is connected to the input end of the voltage regulator, one end of the first current limiting resistor and the moving end of the first relay switch, the other end of the first current limiting resistor is connected to the moving end of the second relay switch, the fixed end of the first relay switch is connected to the fixed end of the second relay switch, one end of the first capacitor and the power supply end of the vacuum sealer, the second output end of the first rectifier, the other end of the first capacitor, the ground end of the vacuum sealer, the ground end of the voltage regulator and one end of the second capacitor are all grounded, and the other end of the second capacitor is connected to the output end of the voltage regulator and the timing control module.

3. The soft start circuit of the vacuum sealer according to claim 2, characterized in that: The timing control module includes a ninth resistor, a first power tube, a first switch tube and a timing control device; The drain of the first power tube is connected to the output end of the voltage regulator and is connected to the collector of the first switch tube and the gate of the first power tube through a ninth resistor. The source of the first power tube is connected to the power supply end of the timing control device. The output end of the timing control device is connected to the soft start control module. The emitter of the first switch tube and the ground end of the timing control device are grounded. The base of the first switch tube is connected to the difference comparison module.

4. The soft start circuit of the vacuum sealer according to claim 3, characterized in that: The soft start control module also includes a tenth resistor, a first relay, a second switch tube, a first diode, a third switch tube and a second relay; The base of the second switch tube is connected to the anode of the first diode and is connected to the output end of the timing control device through the tenth resistor, the cathode of the first diode is connected to the difference comparison module and the base of the third switch tube, the emitter of the third switch tube and the emitter of the second switch tube are both grounded, the collector of the second switch tube and the collector of the third switch tube are respectively connected to one end of the first relay and one end of the second relay, and the other end of the first relay and the other end of the second relay are both connected to the output end of the regulator.

5. The soft start circuit of the vacuum sealer according to claim 4, characterized in that: The voltage sampling module includes a first resistor, a second resistor, a third resistor and a fourth resistor; The first end of the first resistor and the first end of the third resistor are respectively connected to the first output end of the first rectifier and the fixed end of the second relay switch, the second end of the first resistor is grounded through the second resistor, and the second end of the third resistor is grounded through the fourth resistor.

6. The soft start circuit of the vacuum sealer according to claim 5, characterized in that: The difference detection module includes a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a first operational amplifier and a fourth switch tube; The in-phase terminal of the first operational amplifier is connected to one end of the sixth resistor and is connected to the second end of the first resistor through the fifth resistor, the other end of the sixth resistor is grounded, the inverting terminal of the first operational amplifier is connected to one end of the eighth resistor and is connected to the second end of the third resistor through the seventh resistor, the output terminal of the first operational amplifier is connected to the difference comparison module and the other end of the eighth resistor, the base of the fourth switch tube is connected to the difference comparison module, the collector of the fourth switch tube is connected to the power supply terminal of the first operational amplifier, and the emitter of the fourth switch tube is connected to the first end of the third resistor.

7. The soft start circuit of the vacuum sealer according to claim 6, characterized in that: The difference comparison module includes a first comparator, a first threshold device, a second diode, a third diode and an eleventh resistor; The non-inverting end of the first comparator is connected to the cathode of the second diode and the output end of the first operational amplifier, the inverting end of the first comparator is connected to the first threshold device, the output end of the first comparator is connected to the anode of the second diode and connected to the base of the first switching tube and the anode of the third diode through the eleventh resistor, and the cathode of the third diode is connected to the base of the fourth switching tube and the base of the third switching tube.

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