An acceleration overload switch

Abstract

The present invention discloses an acceleration overload switch, which includes an acceleration sensitive unit, a secondary power conversion unit, an acceleration pulse judgment unit and a self-locking electronic switch unit; the secondary power conversion unit converts an external input power supply into a secondary power supply to provide an operating voltage for the acceleration sensitive unit and the acceleration pulse judgment unit; the acceleration sensitive unit converts a carrier acceleration into an analog voltage signal and inputs the signal into the acceleration pulse judgment unit; the acceleration pulse judgment unit generates a control voltage according to the analog voltage signal, and the control voltage is input into the self-locking electronic switch unit to control the conduction of an electronic switch in the electronic switch unit and maintain the self-locking state of the electronic switch until the system loses power, at which time the acceleration switch automatically resets and the electronic switch returns to the disconnected state, so that the electronic switch can achieve self-locking and maintain the state of the electronic switch after the driving signal is removed.

Description

Technical Field

[0001] The invention belongs to the technical field of inertial measurement and relates to an acceleration overload switch. Background Art

[0002] An acceleration overload switch is an inertial device that senses carrier acceleration and triggers a switch contact state change. It determines the carrier's overload acceleration in the direction of its sensitivity and, when the overload acceleration reaches a specified threshold, switches the internal switch into conduction. It is widely used in applications such as ignition control of explosive devices in weapons and aircraft attitude control. An acceleration overload switch primarily consists of an accelerometer and a mechanical / electronic switch. Because mechanical switches rely primarily on the displacement of mechanical components to control the switch's contact and disconnection, this approach results in poor long-term stability and resistance to environmental factors such as vibration and shock. In applications involving high transient currents, the erosion of the mechanical contacts by the current can cause premature failure. Electronic switches, lacking conventional moving mechanical parts, offer advantages such as high sensitivity, stable performance, and strong environmental adaptability. However, electronic switches require a drive signal to maintain the switch on (off). Removing the drive signal causes the switch's state to change, and they lack a self-locking function. Summary of the Invention

[0003] The purpose of the present invention is to solve the problem in the prior art that the electronic switch in the acceleration overload switch maintains the conduction and shutdown of the switch by loading a driving signal. When the driving signal is removed, the state of the electronic switch changes and self-locking cannot be achieved. An acceleration overload switch is provided.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] An acceleration overload switch comprises an acceleration sensitive unit, a secondary power conversion unit, an acceleration pulse judgment unit and a self-locking electronic switch unit;

[0006] The output end of the acceleration sensing unit is connected to the input end of the acceleration pulse judging unit, the output end of the acceleration pulse judging unit is connected to the input end of the self-locking electronic switch unit, and the output end of the self-locking electronic switch unit is connected to the power load; the secondary power conversion unit converts the external input power into a secondary power supply to provide an operating voltage for the acceleration sensing unit and the acceleration pulse judging unit;

[0007] The acceleration sensitive unit converts the carrier acceleration into an analog voltage signal and inputs it into the acceleration pulse judgment unit. The acceleration pulse judgment unit generates a control voltage based on the analog voltage signal. The control voltage is input into the self-locking electronic switch unit to control the conduction of the electronic switch in the electronic switch unit and keep the electronic switch self-locking.

[0008] A further improvement of the present invention is:

[0009] The acceleration sensitive unit is a single-axis MEMS accelerometer, a multi-axis MEMS accelerometer or a quartz flexible accelerometer, and the acceleration sensitive unit is used to convert the carrier acceleration into an analog voltage signal V1.

[0010] The analog voltage signal V1 is proportional to the acceleration of the carrier, and its specific expression is shown in formula (1):

[0011] V1=K·a (1)

[0012] Where K is the accelerometer scale factor and a is the carrier acceleration.

[0013] The secondary power conversion unit includes a three-terminal adjustable voltage regulator U1, a resistor R1, a resistor R2, a capacitor C1 and a capacitor C2; the input end of the three-terminal adjustable voltage regulator U1 is connected to the external input power supply V DD , one end of capacitor C1 is connected to the input end of three-terminal adjustable voltage regulator U1, and the other end is grounded; the two ends of resistor R1 are connected to the adjustment end and the output end respectively, and the adjustment end is grounded through resistor R2, one end of capacitor C2 is connected to the output end of three-terminal adjustable voltage regulator U1, and the other end is grounded; the output of three-terminal adjustable voltage regulator U1 is the secondary power supply V DD1 .

[0014] The secondary power supply V DD1 Provides operating voltage for the acceleration sensitive unit and the acceleration pulse judgment unit, secondary power supply V DD1 The specific expression is shown in formula (2):

[0015]

[0016] Wherein, R1 and R2 are the resistance values ​​of resistor R1 and resistor R2 respectively.

[0017] The acceleration pulse judgment unit includes a comparator U2, a timer U3, a comparator U4, resistors R3 to R8, a resistor R int , capacitor C3 and capacitor C int ;

[0018] The positive input of the comparator U2 is connected to the output of the accelerometer sensitive unit, and the negative input is connected to the resistor R3 and the resistor R4 respectively. The resistor R3 is connected to the secondary power supply, and the resistor R4 is grounded. The output of the comparator U2 is connected to the resistor R5 and the trigger end of the timer U3 respectively. The resistor R5 is connected to the secondary power supply; the control end of the timer U3 is grounded through the capacitor C3, and the threshold end is connected to the resistor R int and capacitor C int , resistor R int Connect the secondary power supply, capacitor Cint The negative input of the comparator U4 is connected to resistors R6 and R7 respectively, the resistor R6 is connected to the secondary power supply, the resistor R7 is grounded, the output end is connected to the resistor R8 and the input end of the self-locking electronic switch unit, and R8 is connected to the secondary power supply.

[0019] When the output voltage of the acceleration sensitive unit is less than the inverting input voltage of the comparator U2, the comparator U2 outputs a low level, the timer U3 outputs a low level, and the comparator U4 outputs a low level; when the output voltage of the acceleration sensitive unit is greater than the inverting input voltage of the comparator U2 but the duration is less than the set value, the comparator U2 outputs a high level, the output voltage of the timer U3 is less than the inverting input voltage of the comparator U4, and the comparator U4 outputs a low level; when the output voltage of the acceleration sensitive unit is greater than the inverting input voltage of the comparator U2 and the duration is greater than the set value, the output voltage of the timer U3 is greater than the inverting input voltage of the comparator U4, and the comparator U4 outputs a high level; the set value is the delay time for the electronic switch to be turned on.

[0020] The comparator U2 inverting input voltage V A and the comparator U4 inverting input voltage V T The specific expressions are shown in formula (3) and formula (4):

[0021]

[0022]

[0023] Among them, V DD1 is the secondary power supply voltage, R3 and R4 are the resistance values ​​of resistors R3 and R4 respectively, and R6 and R7 are the resistance values ​​of resistors R6 and R7 respectively.

[0024] The self-locking electronic switch unit includes a thyristor T1, a field-effect transistor T2, a resistor R9, and a resistor R10; an external input power supply is connected to the resistor R9 and the drain of the field-effect transistor T2 respectively, the gate of the field-effect transistor T2 is connected to the resistor R9 and the resistor R10 respectively, the source is connected to the electrical load, the electrical load is grounded, the resistor R10 is connected to the anode of the thyristor T1, and the cathode of the thyristor T1 is grounded.

[0025] When the acceleration pulse judgment unit outputs a low level, the thyristor T1 is disconnected and the field effect transistor T2 is in the off state; when the acceleration pulse judgment unit outputs a high level, the thyristor T1 is turned on and the field effect transistor T2 is turned on. If the output of the acceleration pulse judgment unit subsequently becomes a low level, the thyristor T1 still remains in the on state, the field effect transistor T2 is turned on, and the thyristor T1 is in a self-locking state.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The acceleration overload switch in the present invention includes an acceleration sensitive unit, a secondary power conversion unit, an acceleration pulse judgment unit and a self-locking electronic switch unit; the acceleration sensitive unit converts external acceleration information into a voltage signal, and the voltage signal is used to generate a control voltage by the acceleration pulse judgment unit. The control voltage is used to control the conduction of the electronic switch of the self-locking electronic switch unit and keep the electronic switch self-locked until the system loses power, at which time the acceleration switch automatically resets and the electronic switch returns to the disconnected state, so that the electronic switch can achieve self-locking and maintain the state of the electronic switch after the driving signal is removed. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without making any creative efforts.

[0029] Figure 1 This is a structural diagram of the acceleration overload switch module in the present invention;

[0030] Figure 2 This is a circuit diagram of the secondary power conversion unit in the present invention;

[0031] Figure 3 This is a circuit diagram of the acceleration pulse judgment unit in the present invention;

[0032] Figure 4 This is a circuit diagram of the self-locking electronic switch unit in the present invention. DETAILED DESCRIPTION

[0033] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more apparent, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. It should be understood that the described embodiments are only a portion of the embodiments of the present invention, not all of them. Generally, the components of the embodiments of the present invention described and illustrated in the drawings herein may be arranged and designed in a variety of different configurations.

[0034] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention as claimed, but rather merely represents selected embodiments of the present invention. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without creative effort shall fall within the scope of protection of the present invention.

[0035] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0036] In the description of the embodiments of the present invention, it should be noted that the terms "upper," "lower," "horizontal," "inner," and the like, used to indicate orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, or are the orientations or positional relationships typically used when the inventive product is in use. These terms are intended solely to facilitate description and simplify the present invention, and are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation. Therefore, they should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and the like are used solely for distinction and should not be construed as indicating or implying relative importance.

[0037] In addition, if the term "horizontal" appears, it does not mean that the component must be absolutely horizontal, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0038] In the description of the embodiments of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "disposed," "installed," "connected," and "connected" should be interpreted broadly. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediary; and internal communication between two components. Those skilled in the art will understand the specific meanings of these terms in the present invention based on specific circumstances.

[0039] The present invention is described in further detail below with reference to the accompanying drawings:

[0040] See also Figure 1 , is a schematic diagram of the acceleration overload switch module structure in the present invention. The acceleration overload switch includes an acceleration sensitive unit, a secondary power conversion unit, an acceleration pulse judgment unit, a self-locking electronic switch unit and other peripheral resistors and capacitors. The output end of the acceleration sensitive unit is connected to the input end of the acceleration pulse judgment unit, the output end of the acceleration pulse judgment unit is connected to the input end of the self-locking electronic switch unit, and the output end of the self-locking electronic switch unit is connected to the electrical load; the secondary power conversion unit converts the external input power into a secondary power supply to provide working voltage for the acceleration sensitive unit and the acceleration pulse judgment unit. The working mode of the acceleration overload switch is as follows: the acceleration sensitive unit converts the carrier acceleration into an analog voltage signal V1. When the voltage V1 amplitude V PPWhen both the acceleration time and the duration T reach the specified values, the acceleration pulse judgment unit generates a control voltage V2, which drives the self-locking electronic switch to turn on and maintain self-locking until the system loses power, at which point the acceleration overload switch automatically resets and the electronic switch returns to the off state.

[0041] The acceleration sensitive unit can be a single-axis MEMS accelerometer, a multi-axis MEMS accelerometer, or a quartz flexible accelerometer, etc., which can output analog voltage or analog current according to actual use requirements. The output voltage of the acceleration sensitive unit is proportional to the acceleration of the carrier. The specific expression is shown in formula (1):

[0042] V1=K·a (1)

[0043] Where K is the accelerometer scale factor and a is the carrier acceleration.

[0044] See also Figure 2 , is a circuit structure diagram of the secondary power conversion unit in the present invention, the secondary power conversion unit includes a three-terminal adjustable voltage regulator U1, a resistor R1, a resistor R2, a capacitor C1 and a capacitor C2; the input end of the three-terminal adjustable voltage regulator U1 is connected to the external input power supply V DD , one end of capacitor C1 is connected to the input end of three-terminal adjustable voltage regulator U1, and the other end is grounded; the two ends of resistor R1 are connected to the adjustment end and the output end respectively, and the adjustment end is grounded through resistor R2, one end of capacitor C2 is connected to the output end of three-terminal adjustable voltage regulator U1, and the other end is grounded; the output of three-terminal adjustable voltage regulator U1 is the secondary power supply V DD1 , secondary power supply V DD1 Provides normal operating voltage for the acceleration sensitive unit and the acceleration pulse judgment unit, where the secondary power supply V DD1 Calculated by formula (2):

[0045]

[0046] See also Figure 3 , is a circuit diagram of the acceleration pulse judgment unit in the present invention, the acceleration pulse judgment unit includes a comparator U2, a timer U3, a comparator U4, resistors R3 to R8, a resistor R int , capacitor C3 and capacitor C int Timer U3 is a 555 timer. The positive input of comparator U2 is connected to the output of the accelerometer sensitive unit, and the negative input is connected to resistors R3 and R4 respectively. Resistor R3 is connected to the secondary power supply, and resistor R4 is grounded. The output of comparator U2 is connected to resistor R5 and the trigger terminal of timer U3 respectively. Resistor R5 is connected to the secondary power supply, and the voltage of the trigger terminal pin drops to 1 / 3V. DD1The output terminal gives a high level; the reset terminal of the timer U3 is connected to the trigger terminal, and the timer works when the reset terminal pin is connected to a high level; the control terminal of the timer U3 is grounded through the capacitor C3, and the control terminal is used to control the threshold voltage of the chip; the threshold terminals are connected to the resistors R int and capacitor C int , resistor R int Connect the secondary power supply, capacitor C int Grounded, when the voltage of the threshold pin rises to 2 / 3V DD1 When the output terminal outputs a low level; the discharge terminal is connected to the positive input terminal of the comparator U4; the negative input terminal of the comparator U4 is connected to the resistor R6 and the resistor R7 respectively, the resistor R6 is connected to the secondary power supply, the resistor R7 is grounded, the output terminal is connected to the resistor R8 and the input terminal of the self-locking electronic switch unit, and R8 is connected to the secondary power supply.

[0047] Comparator U2 inverting input voltage V A and the comparator U4 inverting input voltage V T The specific expressions are shown in formula (3) and formula (4):

[0048]

[0049]

[0050] When the output voltage V1 of the acceleration sensitive unit is less than the inverting input voltage V A When the comparator U2 outputs a low level, the reset terminal of the timer U3 is enabled, the timer U3 outputs a low level, and the comparator U4 outputs a low level; when the acceleration sensitive unit output voltage V1 is greater than the comparator U2 inverting terminal input voltage V A When the comparator U2 outputs a high level, the timer U3 works in the monostable trigger mode, and the capacitor C int Start charging, the charging time constant is 1.1R int C int , the voltage at the output of timer U3 begins to increase linearly, and the resistor R int and capacitor C int The output voltage rising slope can be changed; when the output voltage of the acceleration sensitive unit is greater than the input voltage V A However, the duration t does not reach the set value T th When the output voltage of the timer U3 is less than the input voltage V of the inverting terminal of the comparator U4 during the working time, T , comparator U4 outputs low level, and at the same time, the reset terminal of timer U3 is enabled, and timer U3 is reset; When the output voltage of the acceleration sensitive unit is greater than the input voltage V A And the duration t is greater than the set value Tth When the output voltage of timer U3 is greater than the input voltage V of the inverting terminal of comparator U4 during the working time, T , comparator U4 outputs high level. Set value T th The set value is the delay time for the electronic switch to open, which can be set according to the actual needs of the user.

[0051] See also Figure 4 , is a circuit structure diagram of the self-locking electronic switch unit in the present invention, the self-locking electronic switch unit includes a thyristor T1, a field effect transistor T2, a resistor R9 and a resistor R10; an external input power supply V DD Resistor R9 and the drain of field-effect transistor T2 are connected, respectively. The gate of field-effect transistor T2 is connected to resistors R9 and R10, respectively. The source is connected to an electrical load, which is grounded. Resistor R10 is connected to the anode of thyristor T1, and the cathode of thyristor T1 is grounded. When the acceleration pulse judgment unit outputs a low level, thyristor T1 is turned off, and field-effect transistor T2 is in the off state. When the acceleration pulse judgment unit outputs a high level, thyristor T1 is turned on, and field-effect transistor T2 is turned on. If the acceleration pulse judgment unit output subsequently drops to a low level, thyristor T1 remains turned on, and field-effect transistor T2 is turned on, placing thyristor T1 in a self-locking state. At this point, the self-locking switch will only return to the off state after the external input power is disconnected.

[0052] The acceleration overload switch in the present invention can sense and identify the overload amplitude and overload time of the carrier acceleration. When the overload acceleration amplitude and overload time reach the specified value, the internal electronic switch is turned on and maintains self-locking. The present invention adopts a unique acceleration pulse judgment unit. Compared with the resistance-capacitance filtering solution, it cannot effectively identify the continuous acceleration pulse signal whose overload amplitude and overload time do not reach the specified value. The acceleration pulse judgment unit of the present invention has a self-clearing function; compared with the MCU timing judgment solution, the acceleration pulse judgment unit of the present invention has a small number of components and a simple structure. At the same time, the self-locking function of the electronic switch of the present invention makes the acceleration overload switch conveniently applicable to the ignition control system of weapons and equipment. The present invention adopts an airtight solid-state design and has no conventional mechanical moving parts. It has the advantages of high sensitivity, high reliability, and strong environmental adaptability. It can be widely used in the ignition control of rocket booster systems, high-speed penetrating ammunition, rocket-assisted torpedoes, etc., as well as the field of aircraft carrier acceleration sensitivity measurement, with great economic and social benefits.

[0053] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. An acceleration overload switch, characterized in that: It includes an acceleration sensitive unit, a secondary power conversion unit, an acceleration pulse judgment unit and a self-locking electronic switch unit; The output end of the acceleration sensing unit is connected to the input end of the acceleration pulse judging unit, the output end of the acceleration pulse judging unit is connected to the input end of the self-locking electronic switch unit, and the output end of the self-locking electronic switch unit is connected to the power load; the secondary power conversion unit converts the external input power into a secondary power supply to provide an operating voltage for the acceleration sensing unit and the acceleration pulse judging unit; The acceleration sensing unit converts the carrier acceleration into an analog voltage signal and inputs it into the acceleration pulse judgment unit. The acceleration pulse judgment unit generates a control voltage based on the analog voltage signal. The control voltage is input into the self-locking electronic switch unit to control the conduction of the electronic switch in the electronic switch unit and keep the electronic switch self-locking. The secondary power conversion unit includes a three-terminal adjustable voltage regulator U1, a resistor R1, a resistor R2, a capacitor C1 and a capacitor C2; the input end of the three-terminal adjustable voltage regulator U1 is connected to the external input power supply V DD , one end of capacitor C1 is connected to the input end of three-terminal adjustable voltage regulator U1, and the other end is grounded; the two ends of resistor R1 are connected to the adjustment end and the output end respectively, and the adjustment end is grounded through resistor R2, one end of capacitor C2 is connected to the output end of three-terminal adjustable voltage regulator U1, and the other end is grounded; the output of three-terminal adjustable voltage regulator U1 is the secondary power supply V DD1 ; The acceleration pulse judgment unit includes a comparator U2, a timer U3, a comparator U4, resistors R3 to R8, a resistor R int , capacitor C3 and capacitor C int ; The positive input of the comparator U2 is connected to the output of the accelerometer sensitive unit, and the negative input is connected to the resistor R3 and the resistor R4 respectively. The resistor R3 is connected to the secondary power supply, and the resistor R4 is grounded. The output of the comparator U2 is connected to the resistor R5 and the trigger end of the timer U3 respectively. The resistor R5 is connected to the secondary power supply; the control end of the timer U3 is grounded through the capacitor C3, and the threshold end is connected to the resistor R int and capacitor C int , resistor R int Connect the secondary power supply, capacitor C int Grounded, the discharge end is connected to the positive input end of the comparator U4; the negative input end of the comparator U4 is connected to the resistor R6 and the resistor R7 respectively, the resistor R6 is connected to the secondary power supply, the resistor R7 is grounded, the output end is connected to the resistor R8 and the input end of the self-locking electronic switch unit, and R8 is connected to the secondary power supply.

2. The acceleration overload switch according to claim 1, characterized in that: The acceleration sensitive unit is a single-axis MEMS accelerometer, a multi-axis MEMS accelerometer or a quartz flexible accelerometer, and the acceleration sensitive unit is used to convert the carrier acceleration into an analog voltage signal V1.

3. The acceleration overload switch according to claim 2, characterized in that: The analog voltage signal V1 is proportional to the acceleration of the carrier, and its specific expression is shown in formula (1): V1=K·a (1) Where K is the accelerometer scale factor and a is the carrier acceleration.

4. The acceleration overload switch according to claim 1, characterized in that: The secondary power supply V DD1 Provides operating voltage for the acceleration sensitive unit and the acceleration pulse judgment unit, the secondary power supply V DD1 The specific expression is shown in formula (2): Wherein, R1 and R2 are the resistance values ​​of resistor R1 and resistor R2 respectively.

5. The acceleration overload switch according to claim 1, characterized in that: When the output voltage of the acceleration sensitive unit is less than the inverting input voltage of the comparator U2, the comparator U2 outputs a low level, the timer U3 outputs a low level, and the comparator U4 outputs a low level; when the output voltage of the acceleration sensitive unit is greater than the inverting input voltage of the comparator U2 but the duration is less than the set value, the comparator U2 outputs a high level, the output voltage of the timer U3 is less than the inverting input voltage of the comparator U4, and the comparator U4 outputs a low level; when the output voltage of the acceleration sensitive unit is greater than the inverting input voltage of the comparator U2 and the duration is greater than the set value, the output voltage of the timer U3 is greater than the inverting input voltage of the comparator U4, and the comparator U4 outputs a high level; the set value is the delay time for the electronic switch to be turned on.

6. The acceleration overload switch according to claim 5, characterized in that: The comparator U2 inverting input voltage V A and the comparator U4 inverting input voltage V T The specific expressions are shown in formula (3) and formula (4): Among them, V DD1 is the secondary power supply voltage, R3 and R4 are the resistance values ​​of resistors R3 and R4 respectively, and R6 and R7 are the resistance values ​​of resistors R6 and R7 respectively.

7. The acceleration overload switch according to claim 1, characterized in that: The self-locking electronic switch unit includes a thyristor T1, a field effect transistor T2, a resistor R9 and a resistor R10; an external input power supply is connected to the resistor R9 and the drain of the field effect transistor T2 respectively, the gate of the field effect transistor T2 is connected to the resistor R9 and the resistor R10 respectively, the source is connected to the electrical load, the electrical load is grounded, the resistor R10 is connected to the anode of the thyristor T1, and the cathode of the thyristor T1 is grounded.

8. The acceleration overload switch according to claim 7, characterized in that: When the acceleration pulse judgment unit outputs a low level, the thyristor T1 is disconnected and the field effect transistor T2 is in the off state; when the acceleration pulse judgment unit outputs a high level, the thyristor T1 is turned on and the field effect transistor T2 is turned on. If the output of the acceleration pulse judgment unit subsequently becomes a low level, the thyristor T1 still remains in the on state, the field effect transistor T2 is turned on, and the thyristor T1 is in a self-locking state.

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