Electronic contact opening and closing device

Abstract

The invention discloses an electronic contact switch. A control circuit board comprises a rectifier bridge circuit, a first magnetic reed pipe and a motor driving circuit based on a bidirectional silicon controlled rectifier, an alternating current part of the motor driving circuit is connected with an alternating current power supply, and the bidirectional silicon controlled rectifier is adopted as an electronic switch on a motor power supply loop; the direct current part is a trigger circuit of a bidirectional silicon controlled rectifier; the rectifier bridge circuit takes electricity from an alternating current power supply, and the first magnetic reed pipe is connected in series to a direct current part of the rectifier bridge circuit; a contact (magnet) of the movable contact module is close to the first magnetic reed pipe to conduct the first magnetic reed pipe, so that a direct-current part of a rectifier bridge circuit where the first magnetic reed pipe is located is conducted, a low-voltage direct-current power supply is generated to enable the trigger circuit to work, and then the bidirectional silicon controlled rectifier is triggered to be conducted to enable an alternating-current part of the motor driving circuit to transmit power to the motor to enable the motor to rotate forwards or reversely. According to the invention, the on-off control of the AC driving circuit can be stably and reliably realized, and the overall structure of the shutter is more simplified.

Description

Technical Field

[0001] The present application belongs to the field of railway signal technology, and specifically relates to a switch motor-driven, static contact and non-contact switch. Background Art

[0002] Switch machines are widely used in the field of rail transit. There are many manufacturers and product models, but the internal structures are similar. Take the widely used ZDJ9 AC switch machine as an example. Its internal circuit structure is as follows: Figure 1 As shown, there are two groups of three-position double-throw switches on the left and right, with static contacts 41-46, 31-36 on the left and 21-26, 11-16 on the right. The solid dots represent the moving contacts, which can move left and right to connect or disconnect the upper and lower static contacts. Figure 1 In the figure, contacts 11-14 and 41-44 connect the b and c windings of the motor with the AC380V power supply. When contacts 11-14 are connected and contacts 41-44 are disconnected, the turnout is in the positioned position; when contacts 41-44 are connected and contacts 11-14 are disconnected, the turnout is in the reverse position.

[0003] The designs of the left and right groups of static contacts are usually the same, so usually only the structure of the static contact on one side and its coordination structure with the moving contact are discussed.

[0004] The existing technology mainly adopts mechanical contacts, such as the solutions given in patent documents CN201023491Y (a new reinforced static contact group for railway electric switch), CN201354084Y (redundant defrosting contact group for switch), CN205469117U (balanced redundant contact group for switch), etc. The disadvantages of mechanical contacts are:

[0005] (1) Due to non-sealing, moisture and dust may cause oxidation and contamination of the contacts, increasing the contact resistance;

[0006] (2) Metal fatigue causes contact pressure changes or fractures;

[0007] (3) Improper installation or improper adjustment results in incorrect contact surface posture of the moving / static contacts, asynchronous on / off action of each contact, or inconsistent contact resistance;

[0008] (4) Mechanical wear causes changes in contact resistance and a limited service life.

[0009] In recent years, some scholars have proposed the idea of ​​non-contact. For example, patent document CN115360051A proposed a contactless switch and moving contact group for switch machines, which uses magnetic induction or photoelectric induction to realize the conversion and transmission of switch signals when the moving contact column is driven into or out of the induction tooth mouth on the static contact seat. The magnetic induction scheme mentioned therein is specifically: a specific magnet is fixed on the induction contact of the moving contact. When the moving contact is driven into the induction area of ​​the static contact, the magnetic field in the area changes. At this time, the magnetic induction sensor module embedded in the static contact senses the change in the magnetic field and converts it into an electrical signal and transmits it to the control board module. The control board module processes and logically judges the transmitted electrical signal, and makes it reliably drive the built-in relay or transistor. By connecting and disconnecting the built-in relay or transistor, the corresponding terminal circuit is connected or disconnected.

[0010] However, this solution is essentially just to improve the specific connection method between the moving contact and the static contact, and change the original three-phase (three) mechanical moving contacts to three-phase (three) magnetic induction switches or optical induction switches. Although the above-mentioned disadvantages caused by mechanical contacts (direct contact) can be avoided in theory, it is usually necessary to configure a separate DC power supply and control circuit for these three switches, which significantly increases the complexity of the structure, and the control circuit is always powered, which will consume the service life of the components, and then after a period of time, the circuit performance may become unstable and the reliability may be reduced. Summary of the invention

[0011] The present application provides an electronic contact switch to solve the problem of reduced reliability of existing mechanical contact solutions due to metal fatigue and contact resistance changes, as well as the complex structure of magnetic induction or photoelectric induction dynamic and static contact connection solutions.

[0012] In order to achieve the above objectives, this application provides the following technical solutions:

[0013] An electronic contact switch, comprising a moving contact module and two groups of left and right stationary contact modules, wherein the stationary contact module comprises a control circuit board; the special feature thereof is that the control circuit board comprises a rectifier bridge circuit, a first reed switch and a motor drive circuit based on a bidirectional thyristor;

[0014] The motor drive circuit is divided into an AC part and a DC part, wherein the AC part is connected to an AC power supply and uses a bidirectional thyristor as an electronic switch on the motor power supply circuit; the DC part is a trigger circuit of the bidirectional thyristor;

[0015] The rectifier bridge circuit is divided into an AC part and a DC part, wherein the power supply of the AC part comes from the AC power supply, and the DC part is connected in series with the first reed tube to provide a low-voltage DC power supply to the DC part of the motor drive circuit;

[0016] The contact of the moving contact module adopts a magnet. When the contact of the moving contact module swings to one side and reaches the position, the first reed tube on the control circuit board of the near-end static contact module can be reliably closed, and the first reed tube on the control circuit board of the far-end static contact module can be reliably disconnected; the DC part of the rectifier bridge circuit is turned on by the closure of the first reed tube to generate the low-voltage DC power supply, thereby triggering the bidirectional thyristor to turn on so that the motor power supply circuit is connected to the AC power supply.

[0017] Optionally, the series circuit where the DC part of the rectifier bridge circuit is located has one end connected to the positive terminal Vcc of the low-voltage DC power supply and the other end grounded via the first reed tube; a filter circuit is also provided on the side close to the positive terminal Vcc of the low-voltage DC power supply.

[0018] Optionally, the AC power supply is a three-phase power supply, and accordingly, the AC part of the motor drive circuit is divided into a B-phase circuit and a C-phase circuit, and one of the static contact pairs of the B-phase circuit and the C-phase circuit is respectively connected to the B end and the C end of the three-phase power supply, and is respectively connected to the two ends of the rectifier bridge of the rectifier bridge circuit, so that the rectification obtains the BC voltage of the three-phase power supply; a step-down circuit unit composed of a capacitor Cb and a resistor Re in parallel is also connected in series between any static contact and the rectifier bridge; one of the static contact pairs of the B-phase circuit and the C-phase circuit is connected to the corresponding other static contact via a bidirectional thyristor.

[0019] Further optionally, the static contact pairs of the B-phase circuit and the C-phase circuit each use a bidirectional thyristor as the switch of the circuit, or use two bidirectional thyristors of the same model in parallel as the switch of the circuit. The parallel thyristor structure can reduce the load current flowing through a single thyristor element, and can also maintain the correct contact opening and closing function when a single thyristor has an open circuit fault, thereby improving the reliability of the circuit and extending the service life.

[0020] Further optionally, in the B-phase circuit and the C-phase circuit, a protection circuit consisting of a resistor Rd and a capacitor Ca is connected in parallel at both ends of the bidirectional thyristor.

[0021] Further optionally, the DC part of the motor drive circuit includes the low-voltage DC power supply positive terminal Vcc, a zero-crossing optocoupler and a bidirectional thyristor, the low-voltage DC power supply positive terminal Vcc is connected to ground via the input side of the zero-crossing optocoupler and resistor Ra in sequence, and the output side of the zero-crossing optocoupler is connected to the control end of the bidirectional thyristor.

[0022] Optionally, the static contact module further includes a display circuit for generating a signal related to the current position of the switch machine.

[0023] Further optionally, the indicating circuit uses a reed switch to connect the corresponding static contacts, and the on-off state of the reed switch is also associated with the contact swing position of the moving contact module.

[0024] Further optionally, the display circuit is entirely arranged on a separate display circuit board, or a part of the display circuit is arranged on a separate display circuit board and another part of the display circuit is arranged on the control circuit board;

[0025] The control circuit board and the display circuit board are arranged in a horizontal direction, and the contact of the moving contact module adopts a bar magnet along the horizontal direction, or adopts a plurality of magnets arranged in the horizontal direction.

[0026] Further optionally, the control circuit board and the display circuit board are provided with circuit board protection covers.

[0027] Compared with the prior art, this application has at least the following beneficial effects:

[0028] The contactless switch proposed in the present application has a control circuit board including a rectifier bridge circuit, a first reed switch and a motor drive circuit based on a bidirectional thyristor. The AC part of the motor drive circuit based on the bidirectional thyristor is connected to an AC power supply, and a bidirectional thyristor is used as an electronic switch on the motor power supply circuit; the DC part is a trigger circuit of the bidirectional thyristor; the rectifier bridge circuit draws power from the AC power supply, and the first reed switch is connected in series to the DC part of the rectifier bridge circuit to generate a low-voltage DC power supply. The contact (magnet) of the moving contact module is close to the first reed switch to turn it on, so that the DC part of the rectifier bridge circuit where the first reed switch is located is turned on to generate a low-voltage DC power supply, thereby triggering the bidirectional thyristor to turn on so that the motor power supply circuit is connected to the AC power supply, thereby realizing forward / reverse rotation of the motor.

[0029] The present application breaks through the traditional idea of ​​one-to-one correspondence between the number and orientation of moving contacts (contact swing) and static contacts, and adopts a reed tube to draw power from the original AC power supply through a rectifier bridge circuit, and triggers the bidirectional thyristor to turn on through the generated DC voltage to achieve the required "contact closure". This solution not only avoids the problem of reduced reliability of mechanical contact solutions due to metal fatigue and contact resistance changes, but also achieves stable and reliable on-off control of the AC drive circuit through a clever power supply method (no need to add an additional DC power supply) combined with a bidirectional thyristor; in addition, this electronic contact switch also simplifies the overall structure of the switch.

[0030] In the present application, when the switch machine is in a non-operating state, the control circuit board is not powered on and does not consume electricity, which is beneficial to extending the service life of related components. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more intuitively illustrate the prior art and the present application, exemplary drawings are given below. It should be understood that the specific shapes and structures shown in the drawings should not generally be regarded as limiting conditions for implementing the present application; for example, those skilled in the art are capable of easily making conventional adjustments or further optimizations to the addition / reduction / attribution division, specific shapes, positional relationships, connection methods, dimensional ratios, etc. of certain units (components) based on the technical concepts and exemplary drawings disclosed in the present application.

[0032] Figure 1 This is a schematic diagram of the internal circuit structure of the ZDJ9 type AC switch machine which is widely used in this field.

[0033] Figure 2 This is a schematic diagram of the contact working state of an embodiment of the present application.

[0034] Figure 3 This is a schematic diagram of the basic principles of a control circuit board in one embodiment of the present application.

[0035] Figure 4 A schematic diagram of the topological structure of a control circuit board in one embodiment of the present application.

[0036] Figure 5 A schematic diagram showing the topological structure of a circuit board in one embodiment of the present application.

[0037] Figure 6 It is a schematic diagram of contact connection of an embodiment of the present application when the turnout is in positioning.

[0038] Figure 7 It is a schematic diagram of contact connection of an embodiment of the present application when the turnout is in the reverse position.

[0039] Figure 2 The tags in are as follows:

[0040] 200-moving contact module; 201-swing seat; 202-permanent magnet;

[0041] 300-static contact module; 301-reed switch; 302-circuit board; 303-protective cover; 304-static contact module body; 305-mounting bolt; 306-wire; 307-fixing screw. DETAILED DESCRIPTION

[0042] The present application is further described below in detail through specific embodiments in conjunction with the accompanying drawings.

[0043] In the description of this application: unless otherwise specified, the meaning of "plurality" is two or more. The terms "first", "second", "third", etc. in this application are intended to distinguish the objects referred to, and do not have special meanings in terms of technical connotations (for example, they should not be understood as emphasizing the importance or order, etc.). Expressions such as "including", "comprising", "having", etc. also mean "not limited to" (certain units, components, materials, steps, etc.).

[0044] The embodiments of the present application relate to railway turnout switching technology, and the specific application is a 380V AC power supply conversion switch inside a switch machine, and can also be applied to other motor control applications.

[0045] like Figure 2 As shown, in one embodiment of the present application, the electronic contact switch includes a moving contact module 200 and two groups of left and right static contact modules 300, which can be encapsulated in a housing as a whole. The moving contact module includes a swing seat 201 and a magnet (permanent magnet 202) as a contact, and the contact can swing between the two groups of static contact modules. The physical position of the reed switch 301 on the circuit board 302 of the static contact module is as close as possible to one end edge of the moving contact module 200, so that when the contact of the moving contact module approaches, the reed switch can be reliably closed, thereby realizing the switch conversion. Each group of static contact module body 304 is fixed by mounting bolts 305, and the rear end lead wire structure of the static contact module (such as wire loops, gaskets, etc.) can use the relevant structure of the existing mechanical contacts. For example, the circuit board of the static contact module and the lead wire 306 thereof are fastened to the static contact module body by fixing screws 307. The circuit board 302 can be equipped with a protective cover 303.

[0046] like Figure 3 , Figure 4 As shown, the control circuit board of the static contact module includes a rectifier bridge circuit, a first reed tube Ga and a motor drive circuit based on a bidirectional thyristor; the motor drive circuit is divided into an AC part and a DC part, wherein the AC part is connected to the AC power supply (of the motor), and a bidirectional thyristor is used as an electronic switch on the motor power supply circuit, and the DC part is a trigger circuit of the bidirectional thyristor; the rectifier bridge circuit is divided into an AC part and a DC part, wherein the power supply of the AC part comes from the AC power supply, and the DC part is connected in series with the first reed tube Ga to provide a low-voltage DC power supply to the DC part of the motor drive circuit; the contact of the moving contact module adopts a magnet, and when the contact of the moving contact module swings to one side and is in place, the proximal static contact module (the group of static contact modules close to the magnet side, such as Figure 2The first reed tube on the control circuit board of the static contact module on the left side shown in the figure can be reliably closed, and the first reed tube on the control circuit board of the static contact module at the far end (another group of static contact modules) can be reliably disconnected; the DC part of the rectifier bridge circuit is turned on by closing the first reed tube to generate the low-voltage DC power supply, thereby triggering the bidirectional thyristor to turn on the motor power supply circuit to connect the AC power supply.

[0047] The series circuit where the DC part of the rectifier bridge circuit is located has one end connected to the positive terminal Vcc of the low-voltage DC power supply and the other end grounded through the first reed tube; a filter circuit (RC parallel circuit) is also arranged on the side close to the positive terminal Vcc of the low-voltage DC power supply.

[0048] Comparison Figure 1 and Figure 4 In one embodiment of the present application, electronic switches are used to replace mechanical contacts 11-14 and 41-44. Specifically, for the single-side static contact module: for the drive of a three-phase motor, the AC part of the motor drive circuit can be divided into a B-phase circuit and a C-phase circuit, and one static contact (i.e., contact 13, 11) in each static contact pair of the B-phase circuit and the C-phase circuit is respectively connected to the B end and the C end of the three-phase power supply, and is also respectively connected to the two ends of the rectifier bridge of the rectifier bridge circuit, so that the rectifier obtains the BC voltage of the three-phase power supply; a step-down circuit unit composed of a capacitor Cb and a resistor Re in parallel is also connected in series between any static contact and the rectifier bridge; one static contact (i.e., contact 13, 11) in each static contact pair of the B-phase circuit and the C-phase circuit is connected to the corresponding other static contact (i.e., contact 14, 12) through a bidirectional thyristor.

[0049] In the B-phase circuit and the C-phase circuit, the bidirectional thyristor can also use two components of the same type in parallel as an electronic switch, which can reduce the load current flowing through a single thyristor component and maintain the correct contact opening and closing function when a single thyristor has an open circuit failure. In short, the parallel thyristor structure can improve the reliability of the circuit and extend its service life.

[0050] In the B-phase circuit and the C-phase circuit, a protection circuit consisting of a resistor Rd and a capacitor Ca is connected in parallel at both ends of the bidirectional thyristor.

[0051] The DC part of the motor drive circuit includes a low-voltage DC power supply positive terminal Vcc, a zero-crossing optocoupler and a bidirectional thyristor. The low-voltage DC power supply positive terminal Vcc is connected to ground via the input side of the zero-crossing optocoupler and the resistor Ra in sequence, and the output side of the zero-crossing optocoupler is connected to the control end of the bidirectional thyristor.

[0052] Compared with the solution of the aforementioned patent document CN115360051A, this embodiment has the following advantages:

[0053] (1) No external working power supply is required. The 380V AC voltage between the BC terminals of the static contact is used to generate the VCC DC voltage required by the thyristor drive circuit after voltage reduction, rectification and filtering. The circuit is simple and compact.

[0054] (2) Only one magnetic sensor Ga on the control circuit board can realize the synchronous on and off of the B and C phase power supplies. Compared with multi-channel magnetic sensor elements, it can avoid the potential risks caused by the failure of multiple magnetic sensor elements at the same time, such as the risk of fault amplification caused by the loss of one phase.

[0055] (3) Power is taken from the B-phase and C-phase terminals of the static contact, which has a simple structure. When the switch machine is in a non-operating state, the control circuit board is not powered and does not consume electricity, which is beneficial to extending the service life of related components.

[0056] In addition, the static contact module also includes a display circuit, which is mainly used to generate a signal related to the current position of the switch machine. The display circuit uses a reed tube to connect the corresponding static contacts, and the on and off state of the reed tube is also related to the contact swing position of the moving contact module.

[0057] The indicating circuit can be completely arranged on a separate indicating circuit board, or a part of the indicating circuit can be arranged on a separate indicating circuit board and the other part of the indicating circuit can be arranged on the control circuit board; the control circuit board and the indicating circuit board are arranged in a horizontal direction, so that all the reed switches can be arranged in a line along the horizontal direction as much as possible, and accordingly, the contact of the moving contact module can adopt a bar magnet along the horizontal direction, or a plurality of magnets arranged along the horizontal direction.

[0058] Analysis of the working process of the switch machine:

[0059] When the switch machine starts, AC380V three-phase power is added to ABC, and there is an AC380V voltage between BC. The magnet swings to a position close to the first reed tube Ga, and the first reed tube Ga closes. The trigger circuit of the bidirectional thyristor works and generates a trigger signal. The two bidirectional thyristors are turned on, and the switch machine motor receives 380V three-phase AC power and starts to operate. In this process, the B and C phases of the three-phase AC380V power supply are sent to contacts 11, 13 or 41, 43, so that the motor windings b and c are energized, and the motor phase a is connected to the power supply phase A without passing through the contacts; and the DC power required by the trigger control circuit of the bidirectional thyristor is taken from the AC380V voltage between contacts 11-13 and contacts 41-43. Specifically:

[0060] When the switch machine starts, there is AC380V voltage between 11-13 or 41-43. Under the action of the magnet, the first reed tube Ga is turned on, and the voltage is reduced by Cb. The rectifier bridge has a sinusoidal voltage input, which is filtered by RC to generate a DC working voltage of Vcc. Two zero-crossing photoelectric couplers work, two bidirectional thyristors K1 and K2 are turned on, and three-phase AC380V is added to the switch machine motor. The motor rotates. After reaching the position, the three-phase AC380V is disconnected, Ga is turned off, and the circuit stops working. Rd, Ca, R, and C are protection components.

[0061] like Figure 4 , Figure 5 As shown, the remaining contact pairs (45, 46), (31, 32), (33, 34), (35, 36), (21, 22), (23, 24), (25, 26), (15, 16) are all related to the indicating circuit. Since the voltage and current of the indicating circuit are not high, a reed switch can also be used to implement it.

[0062] like Figure 6 , Figure 7 As shown, the circuits and static contacts related to the motor are marked with colored lines. Only contacts 11-14 and 41-44 are related to the operation of the motor. There is only one magnetic reed switch (i.e., the first magnetic reed switch Ga) that controls whether the motor is running. Other contacts 31-36, 45-46, 21, 26, 15, and 16 are only related to the indicating circuit and have nothing to do with the operation of the motor. The indicating circuit is used to generate signals related to the current position of the switch machine and to check whether the motor winding is normal.

[0063] Two sets of circuit boards, left and right, are installed in a housing. Each set of circuit boards is divided into a control circuit board (such as Figure 4 as shown) and represents the circuit board (as Figure 5 As shown in the figure, the core of each control circuit board is a reed switch Ga and two bidirectional thyristor switches. The bidirectional thyristor switches are driven by zero-crossing photoelectric couplers. The DC working power supply comes from the relevant lines of AC380V, which are stepped down by capacitors and rectified and filtered by full-bridge. The start-up of the DC working power supply is jointly controlled by the switch motor contact magnet and the reed switch Ga. The circuit principles and component parameters of the left and right control circuit boards are the same, and the wiring is adjusted accordingly, so that one of the control circuit boards is responsible for driving the motor forward, and the other control circuit board is responsible for driving the motor reverse. The adjustment of wiring and wiring in this regard belongs to the conventional technical means in this field and will not be repeated here.

[0064] Figure 4 The control circuit board of the embodiment shown also integrates a part of the display circuit ( Figure 4The left part of the figure), G is a reed switch, and R and C are protection elements. It should be understood that this part of the display circuit is relatively independent from the main circuit of the control circuit board (rectifier bridge circuit, first reed switch and motor drive circuit based on bidirectional thyristor), so in actual products, this part of the display circuit may not be set on the control circuit board.

[0065] In order to facilitate compact packaging, the four circuit boards can be of the same shape and size. There are two mounting holes and six crimping screw holes on the circuit board base, and the six crimping screw holes correspond to the six wiring holes on the circuit board. The installation sequence is: first use two M6 bolts to fix the base to the switch machine mounting base, then use 6 M5 screws to put the wire loop into the screws, and then pass the screws through the circuit board wiring holes and screw them into the corresponding screw holes of the base to press the circuit board and external wiring.

[0066] The permanent magnet on the swinging part of the switch motor contact should ensure that when it swings to the left or right dead point, the reed switch contact on the circuit board close to it is reliably closed, and the reed switch on the other side of the circuit board is reliably disconnected. The adaptive design in this aspect belongs to the conventional technical means in this field and will not be repeated here.

[0067] A protective cover can be provided on the outside of the circuit board of the single-sided static contact module, and the protective cover forms a physical isolation between the "contact element" of the static contact module and the contact of the moving contact module. Even the contact of the moving contact module does not need to contact the protective cover, as long as the contact of the moving contact module is close enough to the first reed switch on the control circuit board in the protective cover to make it conductive. The protective cover where the single-sided static contact module is located is not limited to the shape of the side facing the moving contact, and it is not necessary to set a special tooth mouth to cooperate with the contact of the moving contact as in the solution of patent document CN115360051A, but can also be designed as a vertical plane, an oblique plane, etc.; even, considering that the moving contact module and the two groups of static contact modules are integrally packaged in a shell, the protective cover outside the single-sided static contact module can be omitted in theory.

[0068] The electronic contact switch provided in this embodiment breaks through the traditional idea of ​​one-to-one correspondence between the number and orientation of moving contacts (contact swing) and static contacts. It adopts a reed tube to draw power from the original AC power supply through a rectifier bridge circuit, and triggers the bidirectional thyristor to turn on through the generated DC voltage to achieve the required "contact closure". This solution not only avoids the problem of reduced reliability of the mechanical contact solution due to metal fatigue and contact resistance change, but also realizes the on-off control of the AC drive circuit stably and reliably through a clever power supply method (no need to add an additional DC power supply) combined with a bidirectional thyristor; in addition, this electronic contact switch also simplifies the overall structure of the switch.

[0069] The technical features of the above embodiments may be arbitrarily combined (as long as there is no contradiction in the combination of these technical features). To make the description concise, not all possible combinations of the technical features in the above embodiments are described; these embodiments that are not explicitly written should also be considered to be within the scope of this specification.

Claims

1. An electronic contact switch, comprising a moving contact module and two sets of left and right stationary contact modules, wherein the stationary contact module comprises a control circuit board; characterized in that: The control circuit board includes a rectifier bridge circuit, a first reed switch and a motor drive circuit based on a bidirectional thyristor; The motor drive circuit is divided into an AC part and a DC part, wherein the AC part is connected to an AC power supply and uses a bidirectional thyristor as an electronic switch on the motor power supply circuit; the DC part is a trigger circuit of the bidirectional thyristor; The rectifier bridge circuit is divided into an AC part and a DC part, wherein the power supply of the AC part comes from the AC power supply, and the DC part is connected in series with the first reed tube to provide a low-voltage DC power supply to the DC part of the motor drive circuit; The contact of the moving contact module adopts a magnet. When the contact of the moving contact module swings to one side and reaches the position, the first reed tube on the control circuit board of the near-end static contact module can be reliably closed, and the first reed tube on the control circuit board of the far-end static contact module can be reliably disconnected; the DC part of the rectifier bridge circuit is turned on by the closure of the first reed tube to generate the low-voltage DC power supply, thereby triggering the bidirectional thyristor to turn on so that the motor power supply circuit is connected to the AC power supply.

2. The electronic contact switch according to claim 1, characterized in that: The series circuit where the DC part of the rectifier bridge circuit is located has one end connected to the positive terminal Vcc of the low-voltage DC power supply and the other end grounded through the first reed tube; a filter circuit is also arranged on the side close to the positive terminal Vcc of the low-voltage DC power supply.

3. The electronic contact switch according to claim 2, characterized in that: The AC power supply is a three-phase power supply. Correspondingly, the AC part of the motor drive circuit is divided into a B-phase circuit and a C-phase circuit. One of the static contact pairs of the B-phase circuit and the C-phase circuit is respectively connected to the B end and the C end of the three-phase power supply, and is respectively connected to the two ends of the rectifier bridge of the rectifier bridge circuit, so that the rectification obtains the BC voltage of the three-phase power supply; a step-down circuit unit composed of a capacitor Cb and a resistor Re in parallel is also connected in series between any static contact and the rectifier bridge; one of the static contact pairs of the B-phase circuit and the C-phase circuit is connected to the corresponding other static contact through a bidirectional thyristor.

4. The electronic contact switch according to claim 3, characterized in that: In the B-phase circuit and the C-phase circuit, a protection circuit consisting of a resistor Rd and a capacitor Ca is connected in parallel at both ends of the bidirectional thyristor.

5. The electronic contact switch according to claim 3, characterized in that: The DC part of the motor drive circuit includes the positive terminal Vcc of the low-voltage DC power supply, a zero-crossing optocoupler and a bidirectional thyristor. The positive terminal Vcc of the low-voltage DC power supply is connected to ground via the input side of the zero-crossing optocoupler and the resistor Ra in sequence, and the output side of the zero-crossing optocoupler is connected to the control end of the bidirectional thyristor.

6. The electronic contact switch according to claim 1, characterized in that: The static contact module also includes a display circuit for generating a signal related to the current position of the switch machine.

7. The electronic contact switch according to claim 6, characterized in that: The indicating circuit uses a reed tube to connect the corresponding static contacts, and the on-off state of the reed tube is also associated with the contact swing position of the moving contact module.

8. The electronic contact switch according to claim 6, characterized in that: The display circuit is entirely arranged on a separate display circuit board, or a part of the display circuit is arranged on a separate display circuit board and another part of the display circuit is arranged on the control circuit board; The control circuit board and the display circuit board are arranged in a horizontal direction, and the contact of the moving contact module adopts a bar magnet along the horizontal direction, or adopts a plurality of magnets arranged in the horizontal direction.

9. The electronic contact switch according to claim 8, characterized in that: The control circuit board and the display circuit board are provided with circuit board protection covers.

10. The electronic contact switch according to claim 3, characterized in that: The static contact pairs of the B-phase circuit and the C-phase circuit respectively use a bidirectional thyristor as the switch of the circuit, or use two bidirectional thyristors of the same type connected in parallel as the switch of the circuit.

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